FORMATION OF NOx 

IN IRON OXIDE 

PELLETIZING FURNACES 
Final Report 

FORMATION OF NOx 

IN IRON OXIDE 

PELLETIZING FURNACES 

SUBMITTED TO 

MINNESOTA DEPARTMENT OF NATURAL RESOURCES 

DIVISION OF MINERALS 

by 

Robert K. Zahl, Larry A. Haas, 

and John Engesser 

Submitted September 29, 1995 by: 

U.S. Bureau of Mines 

Twin Cities Research Center 

Minneapolis, MN 55417 

and: 

Natural Resources Research Institute - Coleraine Research Laboratory 

University of Minnesota, Duluth 

Duluth, MN 55811 
Formation of NO in Iron Oxide Pelletizing Furnaces 

TABLE OF CONTENTS Page 

LIST OF TABLES 

LIST OF FIGURES ii 

ABSTRACT 1 

1. INTRODUCTION 3 

Formation of nitrogen oxides 4 

Toxicity 6 

Emission regulations 7 

Emission control 9 

2. EQUIPMENT AND PROCEDURES 10 

Gas sampling probe 10 

Emission monitoring equipment 10 

CEM instrument descriptions 10 

Process gas flow measurement 12 

Mass flow calculation procedure 12 

Error analysis 17 

3. GRATE-KILN PRODUCING ACID PELLETS 19 

Furnace description 19 

Discussion of samples 20 

Results for the furnace 23 

4. STRAIGHT-GRATE PRODUCING ACID PELLETS 24 

Furnace description 24 

Discussion of samples 25 

Results for the furnace 26 

5. GRATE-KILN PRODUCING FLUXED PELLETS 28 

Furnace description 28 

Discussion of samples 28 

Results for the furnace 30 

6. STRAIGHT-GRATE PRODUCING FLUXED PELLETS 31 

Furnace description 31 

Discussion of samples 32 

Results for the furnace 35 

7. DISCUSSION 37 

Grate-Kiln 37 

Straight-Grate 38 

Furnace Comparisons 38 

8. CONCLUSIONS 40 

REFERENCES 42 

TABLES 

FIGURES 

APPENDICES 
LIST OF TABLES 

2.1 Weather data for the field study - Hibbing, MN airport 

2.2 Sensitivity analysis for the NOx mass flow calculations 

3.1 Average gas analyses for selected periods for a Grate-Kiln producing acid 

pellets. 

3.2 Feed & product chemistry for the Grate-Kiln producing acid pellets. 

3.3 Summary of measurements for the Grate-Kiln producing acid pellets. 

3.4 Summary of results for the Grate-Kiln producing acid pellets. 

4.1 Average gas analyses for selected periods for a Straight-Grate producing 

acid pellets. 

4.2 Feed & product chemistry for the Straight-Grate producing acid pellets. 

4.3 Summary of measurements for the Straight-Grate producing acid pellets. 

4.4 Summary of results for the Straight-Grate producing acid pellets. 

5.1 Average gas analyses for selected periods for the Grate-Kiln producing 

fluxed pellets. 

5.2 Feed & product chemistry for the Grate-Kiln producing fluxed pellets. 

5.3 Summary of measurements for the Grate-Kiln producing fluxed pellets. 

5.4 Summary of results for the Grate-Kiln producing fluxed pellets. 

6.1 Average gas analyses for the Straight-Grate producing fluxed pellets. 

6.2 Feed & product chemistry for the Straight-Grate producing fluxed pellets. 

6.3 Summary of measurements & estimates for the Straight-Grate producing 

fluxed pellets. 

6.4 Chemical analyses of windbox dust samples from a Straight-Grate producing 

fluxed pellets. 

6.5 Summary of results for the Straight-Grate producing fluxed pellets. 
LIST OF FIGURES 

1.1 Pellet bed inside a laboratory furnace. 

1.2 Photolytic cycle for nitrogen oxides in the atmosphere. 

2.1 Gas sampling probe. 

2.2 Filter and liner insert for the gas sampling probe. 

3.1 Process flow diagram for the Grate-Kiln producing acid pellets. 

3.2 Gas analyses vs. time for the sample GKA-6a 

3.3 Gas analyses vs. time for the sample GKA-5 

3.4 Gas analyses vs. time for the sample GKA-3 

3.5 Gas analyses vs. time for the sample GKA-6b 

3.6 Gas analyses vs. time for the sample GKA-6c 

3.7 Selected operating data during the GKA-3 sampling period. 

3.8 Selected operating data during the GKA-5 sampling period. 

3.9 Selected operating data during the GKA-6a sampling period. 

3.10 Selected operating data during the GKA-6b sampling period. 

3.11 Selected operating data during the GKA-6c sampling period. 

3.12 Measured waste gas flow vs. fan current draw. 

3.13 Combustion curves for the Grate-Kiln producing acid pellets. 

3.14 NO vs. CO2analyses for the Grate-Kiln producing acid pellets. 

3.15 NO„ mass flow vs fuel flow for the Grate-Kiln producing acid pellets. 

3.16 Ratio of NO mass flow to fuel flow for the Grate-Kiln producing acid pellets. 

4.1 Process flow diagram for the Straight-Grate producing acid pellets. 

4.2 Gas analyses vs. time for the sample SGA-WB16. 

4.3 Gas analyses vs. time for the sample SGA-WB18. 

4.4 Combustion curves for the sample SGA-WB18. 

4.5 NO. vs. CO2analyses for the Straight-Grate producing acid pellets. 

4.6 NO mass flow vs fuel flow for the Straight-Grate producing acid pellets. 

4.7 Ratio of NO mass flow to fuel flow for the Straight-Grate producing acid 

pellets. 

5.1 Process flow diagram for the Grate-Kiln producing fluxed pellets. 

5.2 Gas analyses vs. time for the sample GKF-1 

5.3 Gas analyses vs. time for the sample GKF-3 

5.4 Gas analyses vs. time for the, sample GKF-4 

5.5 Gas analyses vs. time for the sample GKF-5 

5.6 Gas analyses vs. time for the sample GKF-6a 

5.7 Gas analyses vs. time for the sample GKF-6b 

5.8 Selected operating data during the GKF-4 sampling period. 

5.9 Combustion curves for the Grate-Kiln producing fluxed pellets. 

5.10 NO vs. CO2analyses for the Grate-Kiln producing fluxed pellets. 

ii 
LIST OF FIGURES, cont. 

5.11 NO mass flow vs fuel flow for the Grate-Kiln producing fluxed pellets. 

5.12 Ratio of NO mass flow to fuel flow for the Grate-Kiln producing fluxed 

pellets. 

6.1 Process flow diagram for the Straight-Grate producing fluxed pellets. 

6.2 Gas analyses vs. time for the sample SGF-WB6. 

6.3 Gas analyses vs. time for the sample SGF-WB10. 

6.4 Gas analyses vs. time for the sample SGF-WB12. 

6.5 Gas analyses vs. time for the sample SGF-WB26. 

6.6 Burn-through temperature and NO for the SGF-WB12 sampling period. 

6.7 Combustion curves for the Straight-Grate producing fluxed pellets. 

6.8 NO vs. CO2analyses for the Straight-Grate producing fluxed pellets. 

7.1 NO„ mass flow vs. fuel flow for all gas samples. 

7.2 Ratio of NO flow to fuel flow vs. fuel flow for all gas samples. 

iii 
FORMATION OF NOxIN IRON OXIDE PELLETIZING FURNACES 

By Robert K. Zah11, Larry A. Haas', and John Engesser2 

ABSTRACT 

A gas sampling survey was conducted to characterize the formation of 

nitrogen oxides in the iron ore pelletizing process. The nitrogen oxide, NOR, 

concentration was determined in various parts of two types of commercial 

furnaces, the Grate-Kiln and Straight-Grate, while producing conventional acid 

pellets as well as fluxed pellets. Process gases were found to contain 43 to 781 

ppm NO„ by volume (wet basis) depending on the furnace and the sampling 

location. A range of 400-700 lb NO2/hr and 2.5 to 4.5 lb NO2/million BTU was 

measured depending upon the furnace type, its operating conditions, and whether 

acid or fluxed pellets were being produced. Generally, mass flow of NO was 

found to correlate with fuel flow to the process. Linear relationships between NO 

mass flow and fuel flow were found for some furnaces where conditions for NO 

formation were substantially similar. The emission rate normalized to fuel input 

was found to increase with fuel input only for one furnace. NO. formation in the 

pellet cooler was not supported by the measurements. 

The work was a collaborative effort between the U.S. Bureau of Mines and 

the Natural Resource Research Institute - Coleraine Minerals Research Laboratory 

as part of the Iron Ore Cooperative Research Committee's program. The work was 

partially funded by the Minnesota Department of Natural Resources - Minerals 

Division, the Iron Ore Cooperative Research Committee as well as the participating 

pelletizing plants. 

Robert K. Zahl and Larry A. Haas, Metallurgist and Research Chemist(retired), 

respectively, Twin Cities Research Center,U.S. Bureau of Mines, 

Minneapolis, MN 

2John Engesser, Engineer, CMRL/NRRI, U of M, Duluth, MN 

1 
1. INTRODUCTION 

Many high temperature mineral and metallurgical processes generate 

oxides of nitrogen by virtue of their reliance on combustion. Nitrogen 

oxides, NOR, were classified as criteria pollutants under the National Air 

Quality Standards of the Clean Air Act passed by Congress in 1990. 

Consequently, greater emphasis has been given, Nationally, to the 

determination and reduction of NO,, from all sources. Most of the previous 

nitrogen oxide research was conducted with simulated gases from mobile 

(mobile vehicles) and stationary sources (power plants). No research has 

been conducted on the formation and destruction of nitrogen oxides in iron 

ore pelletizing processes. 

The iron ore pelletizing process has been well described by a number of 

authors ( /-7)1. Pellet furnaces, besides burning fuel, modify the chemical 

content of the iron and alkaline-earth oxides. Pelletizing, in turn, 

significantly modifies the products of combustion. The process operates at 

elevated temperatures, normally 2400-2475°F, requires high rates of heat 

transfer, and is characterized by gases with high oxygen contents at high 

temperatures for long residence times. Iron ore pelletizing includes the 

following sequential steps: drying, preheating, induration, and cooling. 

Induration is defined as "heat hardening" and includes oxidation and 

sintering. The major portion of the heat is added in the induration step and 

the major portion of the air is added in the pellet cooler. The majority of 

NO„ formation is presumed to be caused by fossil fuel combustion in the 

induration step but high temperatures exist in the cooler and the process is 

significantly different if fluxed pellets are produced. 

There are three types of pelletizing furnaces which heat the pellets by 

different mechanisms. In the two types of furnaces investigated in this 

study, the Grate-Kiln and the Straight-Grate, combustion takes place with 

large amounts of preheated, high temperature air in a high temperature 

refractory-lined chamber. The air:fuel ratio is typically 250-350% of 

stoichiometric requirements. 

No systematic studies have been conducted but it is well known that 

several hundred parts per million are emitted (8) by the pelletizing process. 

To better characterize the process, gas samples from various process 

locations were analyzed. Both the Grate-Kiln and the Straight-Grate 

furnaces were sampled during production of conventional "acid" pellets 

and fluxed pellets. The production of fluxed pellets involves adding 

References are given by italic, underlined numbers in parentheses. 

3 
limestone and dolomite to the iron ore concentrates prior to pelletizing. 

The most effective way of preventing the emission of NO into the 

atmosphere is to suppress it at the source. The most obvious method to 

suppress the formation of NO in any furnace would be selection of "low 

NON" burners. The pelletizing process, however, embodies a unique 

combustion environment and demonstrated "low NO." burner technology is 

not commercially available. To aid development of such technology, a 

systematic base-line study is required to 1) quantify NO production at 

different points in the processes and 2) understand the conditions most 

responsible for NO formation. It is for these reasons that the U.S. Bureau 

of Mines, as part of its Environmental Research Program, and the 

Colleraine Minerals Laboratory of the Natural Resources Research Institute 

of the University of Minnesota, Duluth collaborated to conduct a gas 

sampling survey. This research was funded by The Iron Ore Cooperative 

Research Committee, the Minnesota Department of Natural Resources, the 

U. S. Bureau of Mines and the participating companies in Minnesota's 

pelletizing industry. 

Phase I involved simulating the pellet cooler in the laboratory as well as 

test some of the gas sampling equipment to be used in the field survey (9). 

The pellet cooler has the most hot air and could possibly form nitrogen 

oxides. Localized areas of the pellet bed in the cooler could have high 

concentrations of magnetite and in the presence of air, considerable 

oxidation can occur which can generate a lot of localized heat (5). The 

pellets are porous and temperatures greater than in the bulk pellet bed, 

2280°F, could exist. Catalytic reactions were also considered possible. 

The laboratory study involved heating a bed of pellets in a 17 kilowatt 

electric furnace. The configuration is shown in figure 1.1. The pellets 

were oxidized at bed temperatures up to 2450°F. No NO was detected 

unless a small oxygen-natural gas flame was present. The results of these 

experiments were taken as evidence that NO will not be produced in the 

pellet cooler of a pelletizing plant. 

FORMATION OF NITROGEN OXIDES 

At least six stable oxides of nitrogen have been reported. The order of 

decreasing stability of the three most stable oxides above 600° C are: 

nitric oxide (NO), nitrogen dioxide (NO2) and nitrous oxide (N20). 

In this report, NO is defined as a mixture of NO and NO2. This mixture is 

the most common method of defining NO although in the past, the nitric 

acid and nitrate ion content have also been included. These gases usually 

occur together because they are interconvertible in the atmosphere (10). 

4 
NO2 can be converted to NO and atomic oxygen by ultraviolet sunlight. 

The atomic oxygen can react with air to form ozone which in turn can 

oxidize NO. These reactions, shown in figure 1.2, have been referred to 

as the photolytic NO2cycle (11). 

Fuel combustion is the major source of man-made oxides of nitrogen which 

are produced in approximately equal quantities by stationary and mobile 

sources. In the combustion process, NO is the main direct product and 

only subsequently is the NO partially oxidized to NO2. Experimentally NO 

is measured but the emission rate is usually expressed as NO2. 

NO can be formed by three mechanisms: (1) thermal, (2) fuel, and (3) 

prompt (12-14). "Thermal" NO results from the fixation of the molecular 

nitrogen with atomic oxygen at high temperature. It has been reported 

that the quantity of thermal NO„ formed usually increases exponentially as 

the peak flame temperature is increased above 2200°F (15). Some of the 

commonly accepted mechanisms for the thermal NO formation are 

referred to as the Zeldovich exchange reactions: 

( 1 ) N2+ 0 = NO + N 

(2) 02N = NO + 0 

(3) N + OH = NO + H 

Reaction (1) is the rate-limiting step and it occurs at significant rates only 

at temperatures greater than 2750-2800°F. Kinetic calculations indicate 

that these reactions essentially cease when temperatures fall below this 

range. Atomic nitrogen and oxygen are formed by thermal dissociation of 

molecular nitrogen and oxygen. The concentration of the atomic species is 

known to increase with increasing temperature. In hydrogen-air flames 

reactions 1-3 are the only reactions available to consume atomic oxygen 

whereas in hydrocarbon-air flames, atomic oxygen can react with 

hydrocarbon radicals. Consequently, hydrogen-air flames generally 

produce more NO. than hydrocarbon-air flames 

"Fuel" (also referred to as "chemical") NO results from the oxidation of 

the nitrogen compounds in the fuel. Generally, gaseous fuels, such as 

natural gas and propane, contain very low concentrations of chemicallybound nitrogen. However, in the combustion of coal or fuel oils, 

significant quantities of fuel-bound NO can be generated. 

A third and lesser known type of NO formation is called "prompt" NOR. 

This NO is formed from hydrocarbon radicals (CH, CH2, etc.) generated 

from fuel fragmentation which readily reacts with nitrogen in the 

combustion air to form the hydrogen cyanide (HCN) intermediate. The 

5 
HCN then reacts with oxygen and nitrogen in the combustion air to form 

NO as shown by the following equations: 

(4) CH• + N2= HCN + N 

(5) HCN + OH = CN + H2O 

(6) CN + 02= NO + CO 

Prompt NORformation is usually proportional to the number of carbon 

atoms present in the fuel and it has weak temperature dependence. 

Prompt NORforms early in the combustion process, too early to spatially 

resolve a concentration profile in laboratory experiments. The mechanism 

is generally thought to be significant only in fuel-rich flames which 

inherently produce low NORlevels. However, prompt NORmay be 

important in large industrial turbulent diffusion flames (16,17) even when 

the overall combustion is oxidizing. The prompt mechanism may dominate 

on the fuel-rich side of the flame front and the thermal mechanism 

dominates on the fuel-lean side. 

N20 is the third most common nitrogen oxide and is also referred to as 

dinitrogen oxide, nitrous oxide or laughing gas. Its apparent formation in 

combustion is thought to be due to artifacts of the sampling technique. 

The atmospheric concentration in the troposphere of this long-lived gas 

(estimated atmospheric lifetime of 100 years) is about 0.3 ppm. 

Measurements taken during the past two decades have shown that N20 

concentration is rising at about 0.25 pct/yr. The concentration of this gas 

was not determined in this study. 

TOXICITY 

Even at low levels (0.3 ppm) of NOR , clinical studies have shown- that 

asthmatics experience decreased lung function. NO2is the most toxic of 

the nitrogen oxides. In Japan the maximum 'allowed ambient concentration 

0.02 ppm. The Clean Air Act Amendments (CAAA) reported that 0.05 

ppm NO2can be harmful. NO is not very soluble in water but it is 

deposited on vegetation by being oxidized to nitric acid. NOR-dominated 

acid fogs have been recorded with a pH reading of an astounding 1.7 

value. Nitrogen oxides have been more responsible for the acidity in 

California than sulfur dioxide. In California, the NORemissions exceed 

sulfur oxides by a factor of four. Acid precipitation has been reported to 

have cause extensive forest damage in Germany (EPA/600/S7-90/002) 

NORin the presence of sunlight and free radicals of volatile organic 

compounds (VOC's) can form the most pervasive pollutant, ozone (18,19). 

The reaction produces photochemical smog which can result in 

climatological changes. The precise mechanism that is involved in the 

6 
formation of smog is not clearly understood but it is known that NO. plays 

an important part. Presently, ozone-smog pollution exists in large parts of 

our nation in concentrations unhealthy to breathe. Ozone reduces the 

pulmonary functions and causes asthma attacks, cough, and chest 

discomfort. Ozone has been found to be damaging to human health in 

concentrations as low as 0.1 ppm. It is also harmful to vegetation and the 

Congressional Research Service estimates that the damage to crops and 

forests may be as high as $4.3 billion annually. The depletion of the 

stratospheric ozone layer is expected to increase skin cancer, cataracts and 

birth defects, as well as decrease crop yields. 

In urban areas and for short periods of time, NO2can exceed 150 ppb. 

The average NO. ambient level for both NO and NO2ranges from 20 to 40 

ppb. The nearly constant NO levels are due to the relatively short lifetime 

of NO (between a few minutes and a few days). This is not true for N20, 

which has a long lifetime (100 to 200 years) in the troposphere (1.4). 

Nitrous oxide is the most abundant nitrogen oxide in the atmosphere and is 

not directly hazardous to human health but it is a "greenhouse gas" that 

may contribute to global warming. It also is one of the gases that destroys 

stratospheric ozone. 

EMISSION REGULATIONS 

The nitrogen oxides that are considered the main contributors to 

environmental problems are NO and NO2. California and a number of other 

states are stringently regulating NO emission sources (15). The fee in 

Minnesota for NO. emissions is $18.30 per ton emitted (8.20). 

Since 1971, new boilers come under Federal regulation for NO emissions, 

but more recently, regulations on all combustion sources have become 

more stringent (2 1). NO is one of six chemical species classified as 

criteria pollutants under the National Ambient Air Quality Standards 

(NAAQS) of the Clean Air Act Amendments; this Act, passed by Congress 

in November 1990, was the most comprehensive legislation ever enacted 

in the area of air pollution. Congress included a milestone in Title I of the 

CAAA and after 1996, a 3 %/yr reduction of the NO./VOC ratio is required 

in serious, severe and extremely polluted areas. By the year 2000, NO 

emissions must be cut by 2 million tons to reach an annual level of 11 

million tons (22). 

NO reductions fall under Title I (ozone nonattainment areas) and Title IV 

(acid rain) of the CAAA. In special ozone transport regions (e.g., between 

District of Columbia and Maine), sources emitting more than 100 tons of 

NO per year were expected by the U.S. EPA to expand the NO measuring 

7 
equipment between 1992 and 1995 by 100 million dollars yearly (22). By 

year 2000, every utility is required to have NO,, equipment to meet the 

requirements of Title IV. The purpose of Title IV of the 1990 CAAA is to 

decrease the 1990's NO,, emissions by approximately 2 million tons/year. 

Most of this reduction will come from the utilities (18). 

Section III of the CAAA directs the New Source Performance Standards 

(NSPS) to periodically review and tighten the standards as new technology 

is developed. In 1990, the NO,, limit for residual-oil-fired industrial package 

boilers built after July 6, 1984 was set at 172 ng/J (0.3956 lb/106BTU) 

on a NO2basis which corresponds to about 330 ppm. The most severe 

standards are those of the Southern California Air Quality Management 

District (SCAQMD) which required new sources to comply with Best 

Available Control Technology (BACT). In 1992 the SCAQMD considered 

BACT to be about 40 ppm NO,, (at 3 pct 02) or 0.05 lb/MM BTU. The 

NOxemissions for new boilers with a capacity of 20,000 Btu/h and lower 

is 30 ppm; those over 20,000 Btu/h are limited to 9 ppm. Existing boilers 

are generally limited to 40 ppm. 

Low toxic emission maximums are expected to proliferate as regulation 

stemming from the CAAA are promulgated. Title II of the CAAA targeted 

the industrial emissions. The Act established a specific timetable for the 

EPA to promulgate emission limits for the criteria pollutants and it was 

intended to reduce these emissions by 70-90 pct. 

Enforcement has been left up to the states or local agencies, but they 

must set up standards that are within the Federal guidelines. The basic 

specification is that "ambient" NO,, must be less than 0.05 ppm. This is 

an allowed average over a 24-hour period, not to be exceeded more than 

once per year. Relating ambient standards to "source" (in stack) values is 

complex. Source review programs include new source performance 

standards, prevention of significant deterioration in attainment areas, and 

non-attainment area bubbles, offsets, trading, or banking. 

All NO,, generating plants that have the potential of emitting 100 tons per 

year must meet the compliance deadline of November 1996. 

If the emission level is expressed per unit of weight of toxic per unit 

weight of fuel used or product produced, then the size of production 

operation and the dilution rate is not as important. The EPA standard for 

new nitric acid plants is 3 pounds NO,, per ton of nitric acid produced. For 

incineration wastes, an NO. emission of less than 0.2 lb NO2/MMBTU has 

been targeted. 

8 
EMISSION CONTROL 

There are two alternatives to obtain low NOxemissions: either prevent its 

formation or remove it from the off-gases and a variety of solutions have 

been proposed (22-25). Its formation may be decreased by minimizing the 

residence time of the gas at the peak temperature, keeping the 

temperature as low as possible, and by minimizing the availability of 

oxygen for its reaction with nitrogen. Various methods have been 

proposed for incorporating these principles in combustion processes. Most 

burner manufacturers offer products described as "low NO." burners. The 

manufacturers recognize that all combustion environments are different 

and a burner design that does reduce NOxformation in one environment 

may not in another. The design strategies may involve staging the mixing 

of air and fuel to reduce peak flame temperature or quenching the 

reactions by rapid mixing with air or combustion products. These 

strategies are often successful where furnace temperatures are relatively 

low and where near-stoichiometric conditions prevail. Such conditions do 

not exist in pelletizing furnaces. 

Gas turbines represent a combustion environment somewhat similar to 

pelletizing furnaces. Temperatures are 2600-2800°F at 15% 02. In 

traditional non-premixed combustion NOxemissions are approximately 200 

ppm. Lean premixed combustion techniques, however, can result in 

emissions approximately 20 ppm (17). The techniques employed in 

stationary gas turbines are possible because preheat temperatures are 

limited to 600-700°F. Natural gas and air at 2100-2200°F will auto-ignite 

precluding premix techniques. Extraordinarily rapid mixing would be 

necessary to establish lean combustion in non-premixed systems. Thus, 

iron ore pelletizing presents a unique combustion environment where none 

of the established "low NOx" burner strategies apply. 

A wide variety of proprietary post-combustion NOxcontrol technologies are 

being marketed. These include injection of ammonia or urea with and 

without a catalyst. The performance reported by vendors for many of 

these systems have not been well documented in the independent public 

literature but generally require long residence times at narrow temperature 

ranges. Little primary data are available to demonstrate the actual 

applicability and long-term operation performance of the current generation 

of NOxcontrol technologies. 

9 
2. EQUIPMENT AND PROCEDURES 

GAS SAMPLING PROBE 

The sampling probe used in the field study is similar to the probe shown in 

figure 2.1. The probe was 10 ft long and had a diameter of 1 5/8 inches. 

It was supported by a rail when inserted into a sampling port. The probe 

can withstand high temperature combustion environments outside a flame 

envelope if the water flow is maintained at 5 gallons per minute. If a 

controlled water flow is supplied to the outer jacket, the drain water can 

exit at temperatures greater than the dew point of the gas sample. A filter 

and liner tube, shown in figure 2.2, is supported within the sampling tube. 

The liner could be stainless steel, as used in this study, or quartz if 

secondary reactions within the gas sample are catalyzed by the steel. 

Some laboratory tests (9) were conducted with a 6 mm quartz liner tube 

but no catalytic reactions were noted. 

EMISSION MONITORING SYSTEM 

The continuous emission monitoring, CEM, system that was used for the 

pelletizing plant gas survey was assembled by PACE Associates 

Incorporated of Warrington, Pennsylvania. The CEM System is packaged 

in a self-contained 12 foot by 8 foot by 8 foot shelter. The shelter is 

mounted on a double axle trailer for over the road transport. The shelter is 

provided with electric heaters and an air conditioner for maintaining proper 

working temperatures for the instrumentation. 

The CEM contains a Wet/Dry Gas Conditioner, a NO-NO. gas analyzer, a 

SO2gas analyzer, a 02 gas analyzer, a CO - CO2gas analyzer, a 32 

channel recorder/datalogger and a computer. External to the CEM is a 300 

foot heated umbilical cord for delivery of the emission gas to the CEM and 

an air compressor for providing dry instrument air to the CEM. 

CEM INSTRUMENT DESCRIPTIONS 

Heated Umbilical Cord. The gas sample is transported to the CEM through 

a 0.25 inch diameter teflon tube within an insulated and heated umbilical 

cord which was maintained at 180 degrees Fahrenheit. 

Wet/Dry Gas Conditioner. The conditioner first removes particulate from 

the gas stream. After filtration the sample is divided into two parts. One 

portion is conditioned on a wet basis and the other on a dry basis. 

The portion of the sample that is conditioned on a wet basis is accurately 

diluted with clean dry instrument air (10:1 dilution). This reduces the dirt 

load and the dewpoint of the sample and prevents the deposition of 

10 
particles and the formation of condensate in the analyzers that receive the 

sample. This diluted sample was delivered to the NO-NO, gas analyzer and 

the SO2gas analyzer. 

The portion of the sample that is conditioned on a dry basis is drawn 

through a permeation dryer which drys the sample by transporting water 

vapor continuously across a permeable membrane. The dried sample has a 

dewpoint of approximately 35 degrees Fahrenheit. This sample was then 

transported to the 02gas analyzer and the CO-0O2gas analyzer. 

NO-NO. Gas Analyzer. The NO-NO. gas analyzer is a Model 10A 

Chemiluminescent NO-NO. Gas Analyzer manufactured by Thermo Electron 

Corporation of Hopkinton, Massachusetts. The instrument can measure 

NO and total NO,,. The instrument measures the quantity of NO in the gas 

stream via the chemiluminescent process. When total NO,, is determined, 

the NO,, is thermally converted to NO and the measurement of NO is then 

performed via chemiluminescence. The instrument provides a meter 

readout and a voltage output. 

5122Gas Analyzer. The SO2gas analyzer is a Model 40 Pulsed Fluorescent. 

SO2Analyzer manufactured by Thermo Electron Corporation of Hopkinton, 

Massachusetts. The principle of the SO2analysis is based upon the 

measurement of the fluorescence of SO2produced after the absorption of 

ultraviolet radiation. The instrument provides a meter readout and a 

voltage output. 

0O Gas Analyzer. The 02gas analyzer is a Model IR-2200 manufactured -2 

by Infrared Industries, Inc. of Santa Barbara, California. The instrument is 

an electrochemical analyzer with a disposable sensor cell. The instrument 

provides a digital readout and a voltage output. 

CO-CO2Gas Analyzer. The CO-0O2gas analyzer is a Model IR-732 

manufactured by Infrared Industries, Inc. of Santa Barbara, California. The 

analyzer contains dual-cell detectors and uses non-dispersive infrared gas 

analyzers for measuring the gas concentrations. The instrument 

simultaneously measures both CO and CO2concentrations in the gas 

stream and provides a meter readout and a voltage output for each gas. 

32 Channel Recorder/Datalogger. The recorder/datalogger was 

manufactured by Cole-Parmer. The datalogger is programmable and has a 

RS-232 output which is connected to a computer. The voltage output 

from each analyzer is collected by the datalogger and is transferred to the 

computer via the RS-232 output. The recorder/datalogger also maintains a 

continuous record of each analyzer output via a strip chart recorder. 

11 
Comauter. The computer used to collect the analyzer data is a 

CompuAdd (IBM Compatible) with 640 kilobytes of memory and a 20 

megabyte hard drive. The computer has both a 3.5" disk drive and a 

5.25" disk drive. 

Calibration Gases. Calibration gases for NO-NO., SO2, 02, CO, and CO2 

were purchased from Matheson Gases of Joliet, Illinois. A certified NONO. standard, SRM-2630, was also purchased from The National Institute 

of Standards and Technology to check the Matheson NO-NO. calibration 

gases. The zero gas (Utra High Purity Nitrogen) was purchased from 

Genex Corporation. 

CEM °aeration. Prior to the beginning of an emission gas sampling test, 

the instruments in the CEM were actuated and allowed to warm up for an 

hour. The instruments were calibrated by using the zero gas and the 

calibration gases. After the calibration of each instrument was complete, 

the zero gas and calibration gases were circulated to the instruments. The 

outputs of the instruments were recorded by the computer. The emission 

gas sampling and analyses then began. The outputs from the instruments 

were recorded by the computer at three minute intervals. At the end of 

the sampling test period, the calibration gases were circulated to the 

instruments and outputs were recorded. 

PROCESS GAS FLOW MEASUREMENT 

Measurement of the process gas flow at the sampling point was made 

with a multi-point pitot tube traverse. A 10 ft long "S" type pitot tube 

was available for the study. The traverse was made in accordance with 

standard practice for large ducts except that long up- and down-stream 

pipe lengths were not available. The flow measurements were generally 

made at 1-2 duct diameters from a fan outlet. The flow measurements 

were made by personnel from the participating pelletizing plant who also 

recorded the fan's motor current draw during the traverse. 

MASS FLOW CALCULATION PROCEDURES 

When the process gas flow can be measured at the sampling point, the 

mass flow of NO. is relatively simple to determine. The wet-basis gas 

analysis is used to estimate the molecular weight or density of the gas. 

The volumetric flow of the gas and the NO analysis is then used to 

calculate the volumetric and mass flow of NO2. The gas at the sampling 

point must, of course, be representative of the upstream fuel flow if the 

NO mass flow is to be normalized to the fuel input. 

When the flow of process gas at the sampling location is not known, the 

gas analyses can be used to calculate the mass flow of NO. if the fuel flow 

12 
and pellet feed rates are known. This is the only method that could be 

used for most of the gas sampling campaigns. Process gas flow rates 

were available for some of the tests conducted on the Grate-Kiln making it 

possible to compare the two methods. The pellets are a source of H2O 

and CO2and they consume 02. A general equation can be written using 

methane in place of natural gas: 

F*CH, + 1■1*(a02 +bN2+cCO2+dH2O) - P1 + P2 + P3 ==> 

(Nc+P2+F)*CO2+ (Nd+P3+2*F)*H20 + (Na-P1-2*F)'02+ (Nb)*N2 (1) 

The coefficient F is the number of moles of methane per unit time. The 

coefficients a, b, c, d provide the analysis of atmospheric air and N is the 

number of moles of air per unit time. Since moisture in the air is variable, 

a = 0.20946*(1-d), c = 0.00033*(1-d), and b = (1-a-c-d) are used in 

this report. For typical moisture levels and ambient temperatures d will 

range from 0.003 to 0.011. P1 represents the oxygen consumed by the 

pellets during the sampling period and is expressed as a flow of moles of 

oxygen per unit time. P2 represents the CO2driven off the pellets, moles 

of CO2per unit time, and is dependent upon the amount of carbonates and 

other sources of carbon present. P3 represents the moisture driven off the 

pellets, moles of water vapor per unit time. 

Ideal gas behavior was assumed and volumetric flows at the standard 

reference condition of 70°F and 1 atmosphere were used for all 

calculations. All volumetric flows given in this report are given for 

standard conditions. Ideal gas densities were used for the calculations. 

Depending upon the sampling location some of the pellet factors may be 

near zero or justifiably less than the maximum theoretical amounts 

calculated from pellet analyses. Also, the residence time of the pellets in 

the process is 40-60 minutes and the gas residence time is 3-10 seconds, 

depending on sampling location, and it may be necessary to choose the 

appropriate averaging periods to obtain P1, P2, and P3. For example, it 

may be necessary to compensate for the fact that the H2O is driven from 

the pellets 3-15 minutes, depending on the furnace, before the CO2begins 

to be driven off and the pellets begin to consume oxygen. If the feed rate 

is fairly constant, a long period average may be used with reasonable 

confidence. 

When the total flow of process gas at the sampling location is calculated 

from the 02and CO2analyses, the flow will include all upstream air leaks 

into the process. Air leaks in the sampling system will cause the process 

gas flow to be over-estimated. This procedure is only valid if all upstream 

process gases to the fuel source pass the sampling location. Gas handling 

13 
in the two pelletizing processes is fairly complex and this procedure is not 

valid for all sampling locations without estimating bypass flows. 

To calculate the flow: 

N(R) = {R*(P2 + F) + P1 + 2*F}/{a - Rc}, (2) 

where R is the ratio of 02/CO2 measured at the sampling location. In 

principal, the flow can also be calculated from either the CO2 or 02 

analyses using: 

N(CO2) = (11/11*(P2-P1-F) - F - P2)/(c - M1*(1-d)) (3) 

or 

N(02) = (M2*(P2-P1-F) + 2*F + P1)/(a - M2*(1-d)). (4) 

where M1 and M2 are the measured values CO2 and 02, respectively, in 

units of volume fraction. Care must be taken when using these two 

equations since neither is fully representative of all the parameters in 

equation 1. When the calculated air flows are different, a measurement 

error is indicated. 

By setting equation 3 equal to equation 4 it is possible to solve for one 

parameter or measurement in terms of all others. For example, after 

solving for M2 it is possible to construct the theoretical combustion curve 

over the range of CO2 analyses observed. This procedure is useful to test 

the internal consistency of the data as well as indicate systematic errors. 

For measurements in volume fraction, the equation is: 

M2 = ati*fa *(P2-P1-F) + (1-d)*(P1 + 2 *F)1 - a*(P2 +F) - c*(P1 +2*F)1 

{ c*(P2-P1-F) - (1-d)*(P2+F) (5) 

Assuming ideal gas behavior, the total moist flow at the sampling location 

will be (N+F-P1 +P2 + P3) and the mass flow of NO., expressed as NO2 is: 

NO2, mass/time = Flow * NOx(measured) * Density of NO2. (6) 

In this study the NO„ was measured on a wet basis. If a dry-basis analysis 

is used the flow must be the dry flow, (N*(1-d)-F-P1 +P2). N may be 

calculated if the process gas and fuel flows and pellet parameters are 

known. Then the gas analyses may be calculated using: 

CO2, dry vol % = 100 * (Nc + P2 + F)/(N*(1-d)-F-P1 + P2), (7) 

14 
and 

02, dry vol % = 100 * (Na-2*F-P1)/(N*(1-d)-F-P1+ P2). (8) 

Moisture in the process gas may be calculated using: 

H20, wet vol % = 100 * (Nd + P3 + 2*F)/(N + F-P1 + P2 + P3). (9) 

Equations 3 and 4 or 7 and 8 may be used to validate the calculation of N 

using the ratio, R, but the preferred method is to calculate the theoretical 

combustion curve for a set of pellet parameters and compare the results on 

a graph of 02vs CO2as well as calculate the process gas mass flows. If 

the calculations can not be validated the gas analyses or the pellet 

parameters are probably in error. Generally it is always possible to adjust 

the pellet parameters to force the calculations into agreement but the 

adjusted parameters and/or the process gas flow may be unreasonable. In 

that case the gas analyses are probably in error. 

The pellet parameters P1, P2, and P3 are determined from a chemical 

analysis of the pellet feed and product as well as the feed rate. Pellet 

oxidation is the result of oxidizing magnetite, Fe304, to hematite, Fe2O3, 

and is determined from the ferrous iron, Fe+2, and total iron, Fe', analyses 

of the feed and product expressed as mass fractions. Because pellet 

chemistry can be altered in a number of ways two calculations are 

involved. The maximum theoretical fractional weight gain of dry feed due 

to oxidation is determined from the ferrous iron content of the feed and the 

ratio of the molecular weight of oxygen and the atomic weight of iron: 

Gain = Fe+2(0.25*31.9994/55.847). (10) 

The fractional degree of oxidation of the final pellet product is: 

Oxidation = 1 - ((3*Fe+2)/Fet)). 

Knowing the dry feed rate during the sampling period: 

P1 = (Gain)*(Oxidation)*(Feed)*(1/02density). (12) 

A typical value for (P1/F) is 3.15 scf 02/scf Fuel which means that the 

pellets consume 30-35% more oxygen than is consumed by the fuel. 

The manufacture of fluxed pellets involves the addition of calcium and 

magnesium carbonates. The carbonates are calcined in the process and 

CO2is driven off. Other sources of carbon include organic binders, 

15 
carbonates in the ore and process water, and residual flotation reagents. 

Conventional acid pellets contain a few tenths of a percent carbon 

whereas fluxed pellets contain 1-1.5 % carbon. The maximum theoretical 

rate of evolution of CO2is determined from the carbon analysis of the dry 

feed and the ratio of the molecular weight of CO2and the atomic weight of 

carbon: 

P2 = (C)*(44.010/12.0112)*(Feed)*(1/CO2density). (13) 

Residual carbon is often present in the fired pellets, especially fluxed 

pellets. The degree of calcination may be estimated by using ratios of 

C/Fetor C/Si. P2 is then multiplied by the degree of calcination. Carbon in 

the green pellet feed may vary from 0.2 to 1.5 percent and typical values 

of (P2/F) will range from 0.35 to 3.1 scf CO2/scf Fuel. During acid pellet 

production the pellets give off CO2equivalent to 55-65% of the amount of 

CO2formed by combustion. The typical range for fluxed pellets is 190-

210%. If carbon is present in small amounts as a hydrocarbon then it will 

also consume oxygen but the effect will be masked by variations and 

uncertainties in the Fe+2analysis. 

The parameter P3 is simply: 

P3 = (Pellet Moisture)*(wet Feed)*(1/H20, density). (14) 

Typical values of (P3/F) vary from 10-15 scf water vapor/scf fuel or 5-8 

times the amount formed by combustion. Chemically bound water that is 

driven off at high temperatures may be present on the order of a few 

tenths of a percent. Based on that level (P3/F) would be approximately 

0.3-0.5 scf water vapor/scf fuel or 15-25 % of the water produced by 

natural gas combustion and about the same contribution as moisture in the 

atmosphere on a typical day. Ignoring chemically bound water would have 

a less than 1% effect on the NO. mass flow calculation. Moisture in the 

atmosphere is easy to determine and it was included in all calculations in 

spite of its small effect. Atmospheric moisture and other weather data 

relevant to this study are given in table 2.1 

Clearly, depending on the sampling location, the gas analyses are strongly 

dependent on the pellet feed rate, pellet moisture, degree of oxidation, and 

the amount of carbonates present. For fluxed pellets variations in the feed 

can be much more important than variations in the fuel. Fuel efficiency of 

the pelletizing furnace is also a factor. Variations in P1, for example, will 

be more important as efficiency is increased. 

NO mass flows are often normalized to combustion products containing 

16 
3% 02to facilitate comparisons among fuels and furnaces. Since gas 

chemistry is significantly altered by the pelletizing process and is not 

simply a function of combustion, such a normalization procedure would 

have little meaning. 

ERROR ANALYSIS 

When measured process gas flows are used to determine the mass flow of 

NO,, the main sources of error are the flow measurement and the NO. 

measurement. The NO,, mass flow errors are directly related to the errors 

in these measurements. Volumetric flow measurements depend on gas 

density and the overall gas analysis is also a source of error. Moisture in 

the gas can be determined but its measurement is often difficult and prone 

to relatively greater error. At a sampling location where P3 has the 

maximum effect, variations in pellet feed rate and moisture may have a 

significant affect on the process gas density. In the pelletizing process the 

dry gas density is close to that of air. For air containing 10% moisture, an 

increase to 15% would lead to a decrease of 2.7% in the velocity 

measurement with a pitot tube. For an ill-conditioned flow, the pitot tube 

traverse itself is a major source of error. In this report an error of ± 10% 

was assumed for all process gas flow measurements. There was 

insufficient information to determine if the measurements contained any 

positive or negative bias. 

When process gas flows are not available, the gas analyses and the 

parameters in equation 1 are the sources of error. The use of methane for 

natural gas introduces an error into the calculations. Several data sets 

were analyzed using the natural gas analyses and the results were 

compared with calculations using methane. Depending on the effective 

air:fuel ratio at the sample location the error in using methane was found 

to be -0.002 to -0.11 percent for the mass flow calculations. For fluxed 

pellet production the use of methane would contribute a + 0.2% error in 

the mass flows. In the interest of keeping the equations simple, it was 

decided to ignore these errors. The magnitude of these errors is less than 

expected instrument error and is much smaller than the uncertainties 

associated with the pellet parameters. Ignoring the moisture in the air 

would contribute a -0.4 to -0.8 percent error and ignoring the CO2in the 

air would contribute approximately a -3.0 percent error for acid pellets. 

Since the CO2cannot be ignored it did not seem unreasonable to include 

the moisture in spite of its small contribution. 

Measurement errors are to be expected but the final error in NO,, mass flow 

is not a simple function of the independent measurements. A sensitivity 

analysis was conducted using data obtained for acid pellet production in a 

Grate-Kiln (10/21/93). Equations (2) and (5) were used to calculate the 

17 
NO mass flow. Each measurement and parameter in the equations was 

independently varied by + 5%. The results are shown in table 2.2 for the 

most important parameters. The combined effect of changing all 

parameters is given along with the maximum effect of a ± change. The 

values for pellet moisture are valid for sample locations where the moisture 

has the maximum effect. For fluxed pellet production the pellet 

parameters are more important. For the data obtained on Oct 4, 1993 a 

+ 5% error in estimating P2 would lead to a + 2.3% error in the mass 

flows. These values should only be used as a guide. Every data set 

appears to have different sensitivities to the parameters. 

A sample-line air leak would have the effect of increasing the calculated air 

flows as well as result in a low value for NO.. The effect of a sample-line 

air leak was investigated using the data set obtained on Oct. 21, 1993, 

sample GKA-6b. For example, to correct for an air leak that would have 

raised the 02measurement 1.025 times the actual value, the CO2and NO 

values would have to increase by a factor of 1.135 but the final NO mass 

flow would increase by a factor of only 1.018 when calculated with 

equations 2 and 3. When using measured process gas flows such an air 

leak would lead to a -13% error in the NO mass flow. A further 

discussion of the effect of a sample-line air leak is given in section 5 for 

the Grate-Kiln producing fluxed pellets. 

18 
3. RESULTS: GRATE-KILN PRODUCING ACID PELLETS 

FURNACE DESCRIPTION 

The Grate-Kiln pelletizing furnace consists of a traveling grate that is used 

to dry and preheat the pellets, a rotary kiln to further heat the pellets, and 

an annular cooler to cool the pellets and recuperate heat for the process. 

The process flow sheet and sampling locations, numbered 1-6, for this 

furnace are shown in figure 3.1. 

The grate includes three zones, the first and second down-draft-drying 

(DDD) zones, and the preheat (PH) zone. Wet, green pellets are fed to the 

14.5 ft wide grate to a bed depth of 5-6.5 in. Pellets are completely dried 

in the 72 ft long drying zones. Pellet temperature begins to climb above 

212°F in the 56 ft long PH zone. Depending on the location in the bed, 

the pellets attain temperatures of 800-1803°F and are generally 65 pct 

oxidized and 60-90 pct calcined when they discharge into the kiln. 

The rotary kiln is 130 ft long with an inside diameter of 20 ft. The pellets 

attain a temperature of 2370-2460°F. Very little oxidation (<5 pct) takes 

place in the kiln but the calcination could be completed. The pellets 

discharge into the cooler. The kiln burner was configured for natural gas, 

oil, or coal firing. Only natural gas was used during this test program. The 

burner consists of concentric tubes with air in the center, gas in the first 

annulus, and air in the second annulus. Both air flows are referred to as 

primary air. Air flow through the central nozzle was 72 mcfh and flow 

through the outer annulus was 84 mcfh. The flows are held constant and 

do not vary with the fuel. Consequently, the primary air varies between 

10 and 12% of stoichiometric requirements. The nozzles are designed for 

highly turbulent mixing. The burner produces a typical turbulent-diffusion 

flame. The visible flame envelope was not tight and generally filled a 

roughly conical volume 5-15 ft in diameter and 25-35 ft long. 

The annular cooler is essentially similar to the grate but arranged in a 

circular configuration. Two fans supply air to cool the pellets. The hottest 

air is directed into the kiln, some directly up into the kiln hood but most is 

directed above and along the center-line of the kiln with a large duct. The 

kiln burner is located below the recuperated cooler air duct. The final 30-

35% of pellet oxidation is completed in the cooler. Consequently, the bed 

temperature in the cooler increases before the pellets begin to cool. Due 

to the higher temperatures experienced by the pellets oxidizing the most, 

the final 5-10% of the calcination also occurs in the cooler. 

Gas samples were taken at three locations during the period October 18-

22, 1993. The samples are identified with the prefix GKA representing 

19 
"Grate-Kiln producing Acid pellets". The waste gas fan outlet, sample port 

6, was sampled three times. Those samples are designated as GKA-6a, 

fib, 6c in the order they were taken. The summary of gas analyses are 

given in table 3.1. To avoid complex interactions in the NO„ mass flow 

calculations, all values were maintained with 5 significant figures even 

though only 3 significant figures is justified. The gas analyses are listed in 

Appendix A and are shown in figures 3.2-3.6. Plant operating data were 

also obtained at 3 or 5 minute intervals and are shown in figures 3.7-3.11. 

The natural gas flows were averages over the sampling interval, 3 or 5 

minutes, reported at the end-time. Pellet analyses were provided as shift 

averages and are shown in table 3.2. Averages of plant operating data, 

gas analyses, and the maximum effect of the pellets for selected periods 

are given in table 3.3. The data set for this sampling campaign is the most 

complete. Equation parameters and the results for the combustion and 

mass flow calculations are given in table 3.4. 

The waste gas and preheat fan flows were generally measured early in the 

gas sampling period and variations were estimated with the recorded motor 

current draw. Figure 3.12 shows the results of several measurements of 

the waste gas fan flow and a linear regression with the fan's current draw. 

Some of the data are from measurements made on the same machine 

when fluxed pellets were being produced. The fan's current draw would 

also be affected by the pressure drop through the pellet bed but this data 

was not recorded. Because of that and the scatter in figure 3.12 the 

uncertainty in the measured flow is probably ± 10-15%. Having 

measured values for the process gas flows for seven gas sampling periods 

makes it possible to compare the two methods for estimating the NO. 

mass flow. The measured flows were determined from the recorded fan 

current draw for the selected time periods. The measured process gas 

flows and associated NOxmass flows are given in table 3.4. 

DISCUSSION OF SAMPLES 

The gas samples, GKA-6a through GKA-6c, the waste gas fan exhaust, 

included all contributions from all fuel sources as well as the full effect of 

all the pellet parameters. All of the process gases are drawn through the 

waste gas fan. It was possible to designate five sampling periods for the 

three days spent at this location to calculate NO. mass flows. Certain 

plant operating conditions were purposely changed to form these five 

periods. This sampling location is characterized by modest temperatures 

but high moisture contents. In spite of a heated sample line moisture 

would condense and the line required repeated purging to continue 

sampling. Some of the sampling periods showed evidence that suggests 

air leakage into the sampling system but the sample, designated GKA-6b, 

is the most striking example. The gas analyses for this period shows a 

20 
distinct "saw-tooth" pattern that exactly coincides with sample line 

purging. After each purge flow to the analyzers was restored, the oxygen 

analysis decreased stepwise and all other analyses increased. The average 

stepwise decrease in oxygen was 0.36 vol% implying an air leak that 

raised the average measured oxygen by a factor of 1.021. As noted in 

section 2, correcting for such an air leak would raise the calculated mass 

flow of NO. by 1.8% when computed by means of equations 2 and 5 and 

by 13 % when computed from the measured flows. Since the average, 

uncorrected, analyses were used to determine the results in table 3.4, the 

expected errors are not likely to be more than half these values. 

The GKA-6b sample also poses a more difficult dilemma. Figure 3.13 is a 

plot of 02vs CO2for all "G KA" gas samples. The lines on the graph 

represent the calculated theoretical combustion curves using the 

parameters in table 3.4 whereas the points are the gas analyses which 

form the apparent combustion curves. The 6b sample is obviously far off 

its theoretical combustion curve which is similar for all samples. The 

theoretical combustion curve can be made to coincide with the 

measurements only if 15-25% of the theoretical CO2evolved from the 

pellets and 100% of the theoretical oxygen was consumed. Unless the 

pellets happened to contain significantly less carbon during the sampling 

period, this is an unreasonable assumption and indicates that the gas 

analyses are in error. Those factors would also cause the calculated 

process gas flow to be unreasonably low. Although an air leak is known 

to be present, correcting for the leak would simply move the data points 

along the combustion curves and would not cause the apparent and 

theoretical curves to converge. The authors believe that the 02analyses 

contain an offset error which accounts for most and essentially all the error 

in this data set. No calibration anomalies were noted and the authors were 

unable to determine the cause of this systematic error. Increasing all the 

02analyses by 6.8% would bring the measured values in agreement with 

the theoretical curve and increase the calculated NO. mass flow by a 

factor of 1.055. Of course the CO2analyses could also be in error but 

increasing the CO2analyses would cause the calculated process gas flow 

to be unreasonably low. Results based on the measured process gas flows 

would be unaffected by these calibration adjustments. The 02data also 

exhibit a continual increase during the sampling period while the CO2and 

NO trends show a slight decrease suggesting a continual degradation of 

sample line integrity. The plant operating data, however, suggest that 

these trends may be real. The data were treated assuming the trends are 

related to the process and not an air leak. 

Although the calculated process gas flow is much lower than the measured 

value there are no obvious problems with sample G KA-6a. Sample GKA21 
6c, however, may contain a small constant sample-line air leak. Such an 

air leak would explain the relative differences in the calculated and 

measured process gas flows for this location. If a sample-line air leak of 

15.14% was present the "measured-flow" value would increase and the 

"calculated-flow" value would decrease to 592 lb NO2/hr to bring the 

measured and calculated flows into agreement. Other than the lack of 

agreement, there is no evidence of such an air leak. 

The sample GKA-5, the exhaust of preheat fan 1A, should include the 

effects of pellet parameters P1 and P2 but not P3. It is assumed that the 

kiln exhaust gases and any air leakage into the furnace are fully and evenly 

mixed in the PH zone and pellet oxidation and calcination does not vary 

across the width of the grate. These assumptions allow calculations to 

proceed on the basis that the fuel flow to the kiln and process leak air 

flows are fully represented in this sample even though the flow is split 

between the 1A and 1B fans approximately in the ratio of 60:40. The 

flows were measured for both fans. The CO2analyses for this sample 

were recorded manually from the instrument dial and show virtually no 

scatter. It was assumed that the values are a reasonable estimate of the 

mean, however, the apparent and theoretical combustion curves do not 

coincide. Evidence from performing the mass flow calculations suggests 

that there may have been a bias in the sample where not all of the process 

leak air is represented or a greater proportion of the P1 flow is represented. 

More oxidation could have occurred on the 1 A side of the grate because of 

the slightly greater process gas flow. A calculation was performed 

assuming 60% of the fuel flow, 85.6% of the oxidation, and 66.5% of the 

calcination. The result was a very good correlation between the apparent 

and theoretical combustion curves and an NO. flow of 310.1 lb/hr through 

fan 1A. Since the source of NO was the kiln and 60% of the kiln flow is 

represented, the implied NO„ flow is 517 lb/hr and 3.34 lb/million BTU. 

This is greater than the values obtained from the unsplit flow shown in 

table 3.4 and in much better agreement with the value obtained using the 

measured process gas flow. 

Sample GKA-3 at the kiln exhaust should represent all the fuel flow to the 

kiln but include only partial effect of pellet parameters P1 and P2. It was 

assumed that 35% of the oxidation and 5% of the CO2evolution takes 

place in the kiln and cooler. These values were suggested by the plant 

operators and are the result of a material sampling survey conducted two 

years earlier. Air leakage is known to enter the process at this location. 

Incomplete mixing of the leak air and kiln combustion gases at the 

sampling probe would yield a high or low value for the flow calculations. 

There is no obvious problem with the GKA-3 sample. 

22 
RESULTS FOR THE FURNACE 

The results in table 3.4 are summarized in figures 3.14 and 3.15. The NO„ 

mass flows are given in figure 3.14 and the mass flows normalized to fuel 

consumption are given in figure 3.15. Based on the above discussion it is 

likely that all the values for the 6b sample should be increased by 5-10% 

due to a sample-line air leak and the slope of a line fitted to the data 

should decrease. The scatter among the data determined by measured and 

calculated process gas flows for this sample would be substantially the 

same. The agreement between the measured and calculated process flows 

is generally within ± 10% except for the 6a sample where the difference 

is 22%. The reason for this difference is unknown. As noted above the 

two values for the GKA-5 sample can be brought into closer agreement. 

The GKA-5 sample like the GKA-6 samples should represent the process. 

The reason for the lower NO. mass flows for the GKA-5 sample is not 

known but could have been due to a lower secondary air temperature. 

The mass flow of NO„ is seen to increase with fuel flow. The values 

obtained with measured process gas flows show much less scatter and a 

more obvious fuel-NO„ relationship but it was not possible to judge which 

"method" yielded the more reliable results. Since the NO is produced only 

in the kiln, the conditions for NO. formation are substantially the same for 

all gas samples. The relationship with fuel flow can also be seen in figure 

3.16. Although the pellets contribute CO2, their effect is to "base load" 

the CO2measurements and the variation is mostly due to the variation in 

fuel flow. The small variation in air:fuel ratio in the kiln is also primarily 

affected by fuel flow. 

The data are not available for all sampling periods in this study, but 

variations in the secondary air temperature should also lead to variations in 

NOR . Secondary air temperatures during the GKA-3, GKA-6b, and GKA-6c 

sampling periods were 2184-2196°F, 2150-2164°F, and 2112-2118°F, 

respectively. Fuel use also decreased from 155 mcfh to 135 mcfh in the 

same order. These data are given in figures 3.7, 3.10, and 3.11. The 

combination of fuel and secondary air temperature probably contributed to 

the steepness of the apparent curve in figure 3.15. The fuel flows during 

GKA-6b and GKA-6c were similar and the lower NO mass flow for GKA6c could have been due to a lower secondary air temperature. 

In a private communication with the operators at the participating 

pelletizing plant it was learned that the NO. mass flow results calculated in 

this study were in agreement with stack samples taken to satisfy 

compliance with environmental regulations. 

23 
4. RESULTS: STRAIGHT-GRATE PRODUCING ACID PELLETS 

FURNACE DESCRIPTION 

The Straight-Grate pelletizing furnace consists of a traveling grate with 

alternating updraft and downdraft zones to dry, preheat, indurate, and cool 

the pellets. The process flow sheet for this furnace is given in figure 4.1. 

A "hearth layer" of previously fired pellets is fed to the grate. The green 

pellets form a bed on top of the hearth layer. Total bed thickness is 

generally 13-15 inches with the hearth layer comprising 20-25% of the 

bed. The grate was 13.12 ft wide and each of the 38 windboxes was 

6.56 ft long. The numbers in the figure are windbox numbers, ie. WB1- 

WB38. Baffles separating the hood zones were located as indicated in 

figure 4.1. The bottom of each baffle was approximately 13-14 in above 

the bed except at windboxes 7 and 24 where it was 2-3 in above the bed. 

Not labeled in figure 4.1 is the firing zone, WB17 through WB22, and the 

after-firing zone, WB23 - WB24. 

Each combustion chamber had a diameter of 10.67 ft and a height of 

34.83 ft. The two burners on this furnace were located at the bottom of 

each combustion chamber, centered with and firing along the centerline of 

the crossover duct between each combustion chamber and the firing zone 

hood. There are also two burners mounted at the top of each chamber 

which fire downward but these burners were not in use during the test. 

The lower burners reduce the heat loss from the combustion chambers, 

therefore requiring less fuel than the upper burners. The recuperated 

cooling air, secondary combustion air, is supplied to each combustion 

chamber at the top and the air and combustion products enter the firing 

zone hood through 6 ft ID openings horizontally near the top of the 15 fthigh firing zone hood. A separate supply of recuperated air enters above 

windboxes 23 and 24 (mostly 24) through a 6.75 ft ID duct vertically 

downward through the roof approximately 6 ft above the bed. 

Recuperated air is also directed downward through two 6.75 ft ID ducts in 

the 15 ft-high roof of the preheat zone. 

Each burner consisted of a gas nozzle and an annular primary air nozzle. 

The gas and air mix at the nozzle and into a short mixing pipe before 

injecting into the preheated recuperated air stream. Neither the air nor the 

gas is swirled. The injection occurs at high velocity where the hot 

secondary air makes a right-angle turn toward the firing zone hood. The 

short mixing pipe had a diameter of 5 inches. The primary air flow to each 

burner was approximately a constant 130 mcfh and varied from 20 to 

40% of stoichiometric requirements. 

Gas samples were taken at two locations on April 20 and April 21, 1994. 

24 
The sampling locations were approximately 3 ft above the pellet bed at the 

indicated windbox. The sample at windbox 18 was taken with the 

sampling probe angled steeply upward resulting in a sample that is 

considered well representative of the combustion products from the first 

combustion chamber. The primary air flow pressure to each burner was 

decreased by 50% for part of the WB18 sample period designated "low 

primary air". The summary of analyses are given in table 4.1. Pellet 

analyses are given in table 4.2. Plant operating data were available as 30 

minute averages and are given in table 4.3. The gas analyses are given in 

Appendix B as well as figures 4.2 and 4.3. Secondary air temperatures 

were for this furnace were 1560 ± 10°F during the SGA-WB16 sampling 

period and 1610± 15°F during the SGA-WB18 period. Secondary air 

temperatures are normally 1650-1700°F for this furnace. 

DISCUSSION OF SAMPLES 

The gas sample SGA-WB16 in the hood above windbox 16 should be air 

slightly depleted in 02and slightly enriched in CO2due to pellet oxidation 

and calcination in the cooler. It should represent the secondary 

combustion air for the process but include only part of the P1 and P2 

flows from the cooling zone. Assuming no NO. is produced in the cooler 

there must have been some gas from the firing zone (FZ) in this sample. 

The sample location and configuration of the Grate makes it more likely 

that the FZ gases came from the windbox 17-19 region rather than the 

windbox 22-24 region. With that assumption in mind, a simple volumetric 

ratio of the NO. values in table 4.1 implies that 6.50% of the sample at 

windbox 16 is gas from the firing zone. The average analyses excluding 

SGA-WB18.4 through SGA-WB18.6 were combined to represent the FZ 

gases. The calculation implies that the recuperated cooler air contained 

20.683% 02and 0.1237% CO2on a dry basis. An air flow survey was 

completed by plant engineers 21 months earlier. Those data indicate a 

recuperated air flow of 14880 mcfh that is directed to the preheat zone, 

both combustion chambers, and the after-firing zone. Using the pellet 

parameters P1 and P2 in table 4.3, the implied 02and CO2content of the 

recuperated air, and the estimated flow leads to the conclusion that 59% 

of the oxidation and 17.6% of the CO2evolution occurred in the cooler. 

Both values are higher than expected but not entirely unreasonable. A 

series of dust samples were taken from a sister machine and analyzed (see 

section 6). The results indicated that high values are possible but the 

oxidation in the cooler is more likely to be 40% of the theoretical 

maximum P1 flow. 

The gas sample SGA-WB18 at windbox 18 should be the products of 

combustion from the south combustion chamber but include only part of 

the P1 and P2 flows from the cooler. From the gas flow surveys provided 

25 
by the plant operators and the mass flow calculations it was estimated 

that 13% of the cooler air is diverted to each combustion chamber. A plot 

of 02vs CO2 given in figure 4.4 clearly demonstrates that some error must 

be present because the data do not fall on or near any reasonable estimate 

of the theoretical combustion curve. The curve was computed assuming 

35% of the oxidation and 20% of the calcination occurred in the cooler 

and 13% of the cooler air flow was directed to the south combustion 

chamber. In the graph, any increase in P1 causes the theoretical curve to 

move away from the apparent curve. Increasing P2 moves the curves 

closer but the sample must represent 7% of the maximum calcination and 

0% of the oxidation to bring the curves together. Also, the slopes of the 

curves would be significantly different. With 13% of the cooler flow 

representing 7% of P2max the calculation implies that 54% of the 

calcination takes place in the cooler. It is unreasonable to assume no 

oxidation and so much calcination takes place in the cooler. This implies 

that the gas analyses are in error. The authors examined the instrument 

calibration records and operating logs but were unable to find the source of 

the error. The gas analyses could only be correct if there was an 

unexpectedly large source of CO2or if the fuel was oil rather than natural 

gas. Using the data in table 4.4 a -3% error in the 02measurement or a -

12% error in the CO2measurement or some combination of both is 

implied. The potential CO2 error helps the data analyses for both days. 

The implied error in the mass flow calculations is +2.5% to -9.5%. It 

appears to be a systematic offset error and the relative changes between 

high and low primary air flows are considered significant. 

RESULTS FOR THE FURNACE 

The two combustion chambers provide essentially identical environments 

for the formation of NOx. Consequently, the production for the whole 

furnace can, in principle, be estimated from the operation of one chamber. 

Using the calculated NO„ mass flows for the south combustion chamber 

appearing in table 4.4 yields mass flow values that are linearly related to 

the fuel flow. The data are shown in figure 4.6 along with the regression 

line. Similar behavior for the Grate-Kiln furnace as well as the relation 

between NOxand CO2shown in figure 4.5 lends credibility to the 

observation. Although the fuel flows to the two combustion chambers are 

significantly different, the regression line for the south chamber was used 

to estimate the mass flow of NO„ for the north combustion chamber. The 

results are tabulated in table 4.4. The extrapolation is somewhat 

excessive and, of course, it is sensitive to the slope of the south chamber 

regression line. The two mass flows should be added to obtain the total 

NOxproduction for the process. The total mass flow should then be 

normalized to the total fuel flow. The procedure assumes that the 

26 
formation of NOxis much less affected by the air:fuel ratio in this 

combustion environment than by the fuel flow as long as a large, high 

temperature excess air flow is present. This assumption is discussed later 

in this report. 

In a private communication with the operators at the participating 

pelletizing plant it was learned that the NOxmass flow results calculated in 

this study were in agreement with stack samples taken to satisfy 

compliance with environmental regulations. 

27 
5. RESULTS: GRATE-KILN PRODUCING FLUXED PELLETS 

FURNACE DESCRIPTION 

This pelletizing furnace is identical to the Grate-Kiln previously described 

except for the addition of five burners in the preheat zone and one burner 

in the second down-draft drying (DDD2) zone. Two of the preheat burners 

are rated at 40 million. BTU/hr and three are rated at 20. The DDD2 

burner, rated at 20 million BTU/hr, was operated at a constant 9 million 

BTU/hr during all sampling periods. The process flow sheet and sampling 

locations, numbered 1-6, are shown in figure 5.1. 

Gas samples were taken at five locations during September 28 through 

October 8, 1993. The summary of analyses are given in table 5.1. Pellet 

analyses given in table 5.2 represent shift averages. Plant operating data 

were available every 5 minutes after Oct. 5 and are summarized in table 

5.3. The gas analyses are given in Appendix C as well as figures 5.2 

through 5.8. Some plant operating data are shown in figures 5.9 through 

5.12. 

DISCUSSION OF SAMPLES 

Gas samples GKF-6a and GKF-6b at the waste gas fan exhaust, were 

taken on Sept. 28 and 30, 1993, respectively. These samples represent 

all the fuel used in the process and include the entire effect of pellet 

drying, oxidation and calcination. Plant data are available only as averages 

for these sampling periods. The GKF-6a sample is believed to contain very 

significant sample-line air leaks and was not used to characterize the 

process. It is included only to demonstrate the effect of such leaks. In 

table 5.4 the calculated process gas flow is seen to be approximately 

twice the fan's capacity. 

Gas sample GKF-5 was taken at the 1B preheat fan exhaust, on Oct 4, 

1993. This sample should represent all the fuel used in the process except 

for the small burner in DDD2 and should include the entire effect of pellet 

oxidation and calcination. Plant data are available only as averages for this 

sampling period. 

Sample GKF-4, taken on Oct. 5, 1993, is not representative of all the fuel 

used in the kiln or grate. The port is located near the feed end of the 

preheat (PH) zone of the grate. Much of the kiln exhaust is drawn through 

the pellet bed possibly before fully mixing with the additional air and fuel 

used in the PH zone. Plant operators guess that 70-90% of the kiln 

exhaust is bypassed in this manner but no estimate can made of the 

amount of PH zone fuel represented in this sample. Plant data were 

28 
recorded every 5 minutes during this period but calculating a mass flow to 

represent this location would have no meaning. 

Sample GKF-3, taken on Oct. 6, 1993, should represent the kiln exhaust 

gas and some air leakage into the process. The entire exhaust and leak 

flows are assumed to be fully mixed at the sample point but may not be. 

The sample is representative of the kiln fuel only. It consists of 

combustion products with an unknown amount of air and the P1 and P2 

flows associated with the kiln and cooler. It was assumed that 35% of 

the pellets' oxidation and 5% of the calcination occurs in the kiln and 

cooler. Plant data were recorded every 5 minutes during this period. The 

PH zone fuel was increased from nominally 71 mcfh to 90 mcfh at 32 

minutes into the sampling period and returned to 71 mcfh at 202 minutes. 

No gas composition change was observed when the PH zone fuel was 

changed which indicates that the GKF-3 sample did not contain any PH 

zone gases and implies that this location does represent the kiln exhaust. 

An argument could be made for a small decrease in NO„ at 72 minutes, 40 

minutes after the change, but the statistical significance is in doubt. The 

gas analyses show a distinct change at 145 minutes. The kiln fuel 

increased and 3A fan amps decreased at this time. Those changes are 

consistent with the observed (small) decrease in 02and significant increase 

in CO2. The NO. values also decreased significantly. The significant 

fluctuations in kiln fuel flow during the period 32 to 100 minutes were not 

observed to have much effect on the gas analyses. These observations 

are not consistent with other observations made during this study. 

The GKF-1 and GKF-2 samples taken on Oct. 7 and 8, 1993, respectively, 

should represent recuperated air from the pellet cooler. The mass flow at 

sampling port 1 is estimated to be 10% of the flow at port 2. Some 

combustion products may be represented in the port 1 sample but the 

amount would have to be very small. Complete analyses for port 1 are not 

available but it should represent air that first contacts the pellets and 

would more likely be 02-depleted. A reasonable assumption is for the 

pellets to complete their oxidation early in the cooling cycle. The 02 

analyses are consistent with these assumptions. The port 2 NO analyses 

may indicate some NO formation in the cooler or an analysis error since it 

is highly unlikely that any combustion products could have flowed or 

diffused to this location. The port 1 sample was immediately followed by 

analysis of the ambient air outside of port 1 for 12 minutes. There was a 

0.25-0.50 ppm decrease in the NO analyses when the sampling probe 

was withdrawn and the port closed but the significance of this is highly 

questionable. Since it was never possible to detect any NO formation in a 

bed of hot pellets in a laboratory furnace and the GKF-1 and 2 samples 

have very low NO. values, it is assumed that NO formation does not occur 

29 
in the cooler. 

RESULTS FOR THE FURNACE 

Figures 5.9 and 5.10 are plots of 02and NO,, vs CO2, respectively, for all 

gas samples taken during the fluxed pellet campaign. The combustion 

curves demonstrate the data are internally consistent. The implied relation 

between NOxand fuel flow in figure 5.10 is consistent with previous 

observations. When the NO,, mass flows and NO,, flow-to-fuel ratio are 

plotted against fuel flow, figures 5.11 and 5.12, the relations are not as 

clear as with the GKA and SGA samples. The scatter in the data may be 

due to variations in the feed and the ultimate effect of the pellet 

parameters which are more important for fluxed pellet production. It was 

not possible to make judgements for individual samples that would serve to 

reduce the scatter between the results determined from measured gas 

flows and calculated gas flows. The agreement between the two results 

was generally within a t 10% range of uncertainty. 

In a private communication with the operators at the participating 

pelletizing plant it was learned that the NO,, mass flow results calculated in 

this study were in agreement with stack samples taken to satisfy 

compliance with environmental regulations. 

30 
6. RESULTS: STRAIGHT-GRATE PRODUCING FLUXED PELLETS 

The sampling campaign for this furnace produced data that apparently 

contain significant errors. The data are presented for completeness and to 

demonstrate the subsequent analysis for this type of furnace. 

FURNACE DESCRIPTION 

This pelletizing furnace is almost identical to the traveling grate previously 

described except for the addition of 8 burners. The process flow sheet is 

given in figure 6.1. Not labeled is the firing zone in the windbox 18-22 

region and the after-firing zone in the windbox 23-24 region. Baffles 

separating the hood zones were located as indicated in figure 6.1. The 

bottom of the baffle at windbox 11 was approximately 13-14 inches above 

the bed and the baffles at windboxes 7 and 24 were 2-3 inches above the 

bed. Because there are no baffles between windboxes 12-24 considerable 

mixing of the combustion products from all 10 burners could occur in the 

hood area. As in the previously described Straight-Grate, a bed of green 

pellets is placed on top of a bed of fired pellets, the hearth layer. 

Each combustion chamber had a diameter of 10.67 ft and a height of 

34.83 ft. The main burners were located in the roof of each combustion 

chamber and fire downward. The recuperated cooling air is supplied to 

each combustion chamber at the top and the air and combustion products 

enter the 15 ft-high firing zone hood through 6 ft ID openings horizontally 

into the top of the firing zone hood. A separate supply of recuperated air 

enters above windboxes 23 and 24 (mostly 24) through a 6.75 ft ID duct 

vertically downward through the roof approximately 6 ft above the bed. 

This is designated the after-firing zone. Air preheat temperatures for this 

furnace are normally 2000-2100°F which is more like a Grate-Kiln than the 

Straight-Grate producing acid pellets. 

There were eight burners firing into the 9.75 ft-high preheat zone hood, 

four on each side of the furnace. The four pairs of burners were located 

above windboxes 13, 14, 15 and 16. The four burners above windboxes 

13 and 14 are controlled together but separately from the four above 

windboxes 15 and 16. The two preheat control zones as well as each 

combustion chamber are controlled separately to obtain the desired 

temperature profile in the furnace. Each preheat burner is located at the 

center-line in the horizontal section of a 4 ft diameter downcomer that 

supplies hot recuperated air. The center-line is approximately 6 ft above 

the pellet bed and each burner is approximately 12 ft from the center-line 

of the furnace. The preheat burners are designed to induce a recirculating 

flow of furnace gases, in this case hot air, through the burner tile by 

means of the fuel and primary air injector. The injector is an arrangement 

31 
of two concentric pipes with the fuel in the center pipe. The injector is 

located at the entrance of a venturi with a 4.75 inch diameter throat and 

8.25 inch diameter exit nozzle. 

Gas samples were taken at four process locations on four successive days 

from November 29 through December 2, 1993. All sampling locations 

were in the hood approximately 3 ft above the pellet bed at the noted 

windbox. The summary of gas analyses are given in table 6.1. Pellet 

analyses are given in table 6.2. Estimated plant operating data for the 

sampling campaign are given in table 6.3. The gas analyses are given in 

Appendix D and figures 6.2 to 6.5. 

Several months after the sampling campaign a series of dust samples was 

obtained from the individual windbox dust legs. These samples were used 

in an attempt to estimate the progress of pellet oxidation and calcination 

as the pellets travelled from WB12 to WB24. The samples contained 

mostly recognizable pellet fragments. The samples were dry-screened and 

only the dust fraction smaller than 100 mesh was analyzed. Some 

samples•had insufficient dust for chemical analyses. It is reasoned that the 

fine dust is the fraction most likely to have come from the green pellet 

layer whereas the coarser material could easily have come from the hearth 

layer. Partial chemical analyses are given in table 6.4 and indicate that 

only 50-60% of the oxidation and 40-50% of the calcination is completed 

by the time the pellets reach windbox 24. The degree of oxidation appears 

to lead the degree of calcination throughout the process although, 

logically, there shouldn't be a large difference. Based on these samples 

there appears to be some rational for assuming 30-50% of the oxidation 

occurs in the cooler for the Straight-Grate. A range of 50-60% of the 

calcination occurring in the cooler appears to be excessive but the data do 

support a value larger than that used for the Grate-Kiln. A large amount of 

calcination could occur toward the very end of the firing cycle and a range 

of 30-50% of the calcination could be assumed to occur in the cooling 

zone. 

DISCUSSION OF SAMPLES 

Analysis of the gas sampling data were found to be extraordinarily difficult 

due to the complexity of the flow pattern, limited availability of plant 

operating data, no flow measurements, and the numerous assumptions 

that were required. There was a significant process upset prior to the 

SGF-WB12 sampling period leading to additional uncertainties. For each 

assumption reasonable estimates for the parameters in equations 2-5 could 

be adjusted to obtain a wide range of results. 

The gas sample at windbox 6 should include air plus some of the pellet 

32 
moisture. If the sample was taken much further downstream or at the 

hood exhaust fan, more but not all of the pellet moisture would have been 

represented. Pellet moisture is removed while the pellets travel from 

windbox 1 to 10 or 11. If it is assumed that very little moisture is 

removed above windbox 1 then the simplest assumption would lead to the 

expectation that 1/10 of the pellet moisture is removed by the hot air from 

each successive windbox. From the gas analyses given in table 6.1, 

however, it is clear that some gases from the downdraft drying zone (DDD) 

must have mixed with the moist air above windbox 6. Air from the second 

cooling zone can be assumed to contain no NON. If the WB10 sample is 

representative of the DDD zone gases, a simple volumetric ratio of the NO 

values in table 6.1 implies that the sample at windbox 6 contains 27.5% 

gases from the DDD zone and 72.5% is air plus moisture. The moisture 

should probably be 10-20% of the maximum P3 flow given in table 6.2. 

The sample demonstrates the large amount of cross-flow between zones in 

the hood of a Straight-Grate. 

The gas sample SGF-WB26 should be air with small P1 and P2 flows but 

may contain some gases from the firing and after-firing zones above 

windboxes 19-24. Assuming no NO is formed in the cooling zone the 

sample must have contained combustion products from the firing zone 

despite of the seal at the baffle between windboxes 24 and 25. Using the 

analyses SGF-WB12 to represent the gases above windboxes 21-24 is a 

significant assumption but no alternative is available. NO ratios imply that 

the WB26 sample contained 2.29% gases from the firing zone but the CO2 

concentrations imply less than 1 %. Further analyses of the data were 

attempted but all calculations implied either that the gas analyses 

contained significant errors or the cross-flow gases were considerably 

different from the WB12 sample. The NO./CO2ratio, for example, would 

have to be lower. It was not possible to confirm that a large amount of 

oxidation and calcination occurs in the cooler. No further analysis of this 

sample is presented. 

The gas samples taken at windbox 12 and 10 can, in principle, be used to 

estimate the NO„ emissions from the furnace. Two approaches can be 

used subject to different assumptions. The windbox 10 sample could be 

assumed to represent most or all of the preheat and firing zones as well as 

most or all or all of the effects of pellet oxidation and calcination, the P1 

and P2 flows. The windbox 12 sample could be assumed to represent part 

of the preheat zone or all of the preheat and firing zone gases but only part 

of or all of the pellet oxidation and calcination that occurred in the cooler. 

If all of the burners generate NO at equivalent rates per unit heat input, 

then either sample could be used to represent the entire furnace. If the 

burners do not generate NO at the same normalized rate then the samples 

33 
must be analyzed separately to represent different portions of the furnace. 

The NOxmass flows would then be added together to estimate the total 

emissions from the furnace. Of course, the furnace must be operating 

with the same fuel flows, air preheat temperatures, and production rates 

during the two sampling periods. 

Daily pellet production rates were provided and used to estimate the hourly 

pellet feed rates during the sampling periods. Those data are given in table 

6.3. A daily fuel consumption estimate was provided for the day the SGFWB12 sample was taken. The data implied an average fuel consumption 

of 0.622 million BTU per long ton of dry pellet product for the day. The 

fuel and feed rates normally vary during a 24 hour period and the values 

during the sampling period are not known. Assuming a ± 25% demand 

variation, the fuel flow during the SGF-WB12 sampling period was 

estimated to be 167 ± 42 mcfh. The same methodology yielded a fuel 

flow estimate of 208 ± 52 mcfh during the SGF-WB10 sampling period. 

Those data are given in table 6.3 as fuel estimate A. Fuel estimate B is 

the result of a 10 day average fuel consumption of 0.548 million BTU per 

long ton of dry pellet product that was determined a few months earlier. 

Figure 6.6 demonstrates that there was a significant excursion in the 

operation of the furnace during the WB12 gas sampling period. The burnthrough temperature is the average of two measurements below the pallet 

cars in windboxes 22 and 24. Fuel flow will automatically increase when 

this temperature decreases sharply. The graph clearly demonstrates the 

strong relationship between NOxformation and fuel flow. A graph of the 

burn-through temperature for the WB10 sampling period was also made 

available. It shows a slow decrease from 900 to 880 F during the 

sampling period, and the whole graph implies a fairly steady operation. 

Figure 6.7 and 6.8 present the combustion curves and the relation 

between NO„ and CO2, respectively. As in previous sections of this report, 

the combustion curves demonstrate the internal consistency of the data 

and the NOxappears to follow the fuel flow. 

The gas sample at windbox 10 should include combustion products from 

most of the fuel, excess air, and most of the theoretical maximum P1 and 

P2 flows. The sample may be assumed to represent the flows through 

windboxes 15-24 even though some of that flow is bypassed before 

reaching the hood over windboxes 8-11. The assumption requires that no 

air entered the furnace between the bypass and the hood. Some gases 

from the preheat zone (PH) may also be present but there were no 

independent means to determine if that was true. Oxidation and 

calcination that occurs in the windbox 12-14 region and the portion of the 

34 
cooler air flow that is directed to that region were not represented in the 

WB10 sample. The sample was assumed to represent 60% of the 02 

consumed by the pellets. To balance the flows calculated by equations 3 

and 4 the sample was assumed to represent 52.2% of the calcination. 

The third pair of preheat burners are directly above windbox 15 which is 

evenly split between the Windbox Recuperation Fan and the Windbox 

Exhaust Fan. The sample SGF-WB10 would represent 73% of the fuel if 

the flows were perfectly balanced. If the combustion products from the 

third pair were to go fully in one direction or the other, the fuel 

representation would be 73 ± 7%. Although these assumptions are not 

unreasonable, they are only educated guesses. From the values in table 

6.3 and assuming 73% of the indicated fuel flow, 152 ± 38 mcfh, was 

represented by the gases at windbox 10, the NOxmass flow for this 

location in the process was 321 ± 43 lb NO2/hr and 2.12 ± 0.30 lb 

NO2/million BTU. The higher NOxmass flow corresponds to the lower 

normalized ratio with the fuel. The same calculations estimate the process 

gas flow was 15406 ± 2000 mcfh which implies that the low fuel rate is 

more likely because this flow is too high for the fan. That is, values closer 

to 278 lb NO./hr and 2.44 lb NOx/MMBTU at an implied fuel flow of 114 

mcfh are more likely. A wider range of conditions is given in table 6.7, 

particularly at the lowest fuel flows with 65-75% of the oxidation 

represented in the sample. 

The gas sample SGF-WB12 should include combustion products from some 

of the fuel and excess air. The sample may also contain some gases from 

the DDD zone. The mixing of gases between the PH and DDD zones is 

dependent on the respective hood and windbox pressures. Since the 

samples at windbox 10 and 12 were taken one day apart the direction of 

mixing could be different. No mixing was assumed. The sample is 

assumed to represent the flows through windboxes 12-14. To account for 

oxidation and calcination in the cooler, 02consumption and CO2evolution, 

P1 and P2 were 9.7 and 21.96 mcfh, respectively. The data are presented 

in table 6.5. Assuming this sample represents 27% of the fuel flow, 47 ± 

12 mcfh, the mass flow was 205 ± 50 lb NO2/hr and 4.55 ± 0.17 lb 

NO2/million BTU for this location. The process gas flow estimate through 

windboxes 12-14 that this sample represents was calculated to be 2836 

± 600 mcfh. A wider range of conditions is given in table 6.6 at the 

lowest fuel flows with 9-15% of the oxidation represented in the sample. 

RESULTS FOR THE FURNACE 

The whole process could be characterized by the sum of the mass flows 

calculated from the WB10 and WB12 analyses. This would be valid if the 

fuel consumption and pellet feed rates, etc. were the same on both days. 

Unfortunately, the pelletizing furnace was operating at a much lower 

35 
production rate on the second day. Only a single estimated fuel flow is 

available eliminating the possibility of measuring the slope of the NO2mass 

flow with fuel flow. Therefore, there appears to be no rational basis for 

normalization based on the available data. It was noted, however, that the 

WB10 sample was most likely representative of operations at the lower 

range of the given fuel flow. This means that the fuel flow rates during 

the WB10 and WB12 sampling periods may have been fairly close. If that 

were true the mass flows can be added to represent the process. The 

resulting mass flow is 483 lb NO2/hr and 3.00 lb NO2/million BTU although 

it is unclear how to establish an error range to these estimates. 

If it were assumed that the combustion environments for all ten burners 

were not radically different then either the WB10 or WB12 samples could 

be considered representative of the entire preheat and firing zones, WB12-

24, and, therefore, the furnace. Results based on that assumption are 

given in tables 6.6 and 6.7 for the estimated fuel flows, ± 25%, and 

appropriate estimates of oxidation. In all cases the calcination values were 

selected to yield the same calculated air flows from equations 3 and 4 for 

the given oxidation estimates. The resulting values are consistent with the 

data presented in table 6.4. The WB10 sample analysis results in a 

process gas flow that is too large unless the fuel flow was much lower 

than expected. The WB12 sample analysis yields process gas flows that 

are considered low but not unreasonable. These calculations suggests that 

the preheat burners produce more NOxper million BTU than the two main 

burners and this method of analysis should not be used. 

In a private communication with the operators of the participating 

pelletizing plant it was learned that stack testing for compliance with 

environmental regulations has repeatedly yielded values of 900-1200 lb 

NO2/hr for this furnace at fuel flows ranging from 160 to 210 mcfh. This 

implies that the WB12 sample may be a fair representation of the hood 

gases over windboxes 12-24. However, the extraordinarily wide range of 

results for what could be considered reasonable estimates of operating 

conditions readily demonstrates that this study could not determine the 

mass flow of NO„ for this furnace with any degree of certainty. 

36 
7. DISCUSSION 

All the flames in the two pelletizing furnaces sampled for this study have 

some basic similarities relevant to NO„ formation. In all cases a fuel flow 

varies on demand and a flame is established within a refractory-lined 

chamber containing a large volume of air preheated to 1650-2200°F. The 

fuel-air mixing rates probably varied from burner-to-burner and the effective 

air:fuel ratio within each flame envelope also probably varied. In all cases, 

however, the amount of hot secondary air in the neighborhood of the 

flame envelope was 2-4 times the fuel's requirements. That is, the flame 

is established within a volume of hot air that does not directly participate 

in the combustion reactions but only mixes with the combustion products 

when the reactions are substantially complete. By this reasoning, the 

environment for producing NO,, is determined by the volume of the flame 

envelope, the temperature of the secondary air, the radiative heat loss to 

the surroundings during combustion, and to a lessor extent the rate of 

mixing prior to and during combustion. The mixing of the combustion 

products with the remaining air then serves to quench the NO,, reactions. 

More rapid quenching would serve to lower the NO. production from the 

furnace. This reasoning is consistent with the general observation that 

NO,, increases with fuel flow. NO„ mass flows for all the samples are given 

in figure 7.1 which demonstrates this general trend. The same trend 

appears in figure 7.2 which demonstrates that NO,, is also generated at a 

higher rate per unit heat input as the fuel flow to a furnace is increased. 

Only for the SGA samples is the trend clearly seen with little scatter. 

Where the combustion conditions are significantly different, ie. different 

furnaces and different burner configurations, the groupings maintain the 

trend. 

GRATE-KILN 

The two samples GKA-3 and GKF-3.1 represent virtually identical 

combustion environments, the kiln in a Grate-Kiln. The fuel flow in both 

cases was 149 ± 1 mcfh but the NO,, mass flow was 400 lb/hr for GKF3.1 and 637 lb/hr for GKA-3. The air flow for GKF-3.1 was 350% 

stoichiometric fuel requirements and it was 500% for GKA-3. The 

secondary air temperature was 100°F higher for the GKA sample. 

Although oxygen content should have some effect on NO,, formation, it is 

unlikely that variations in 02concentrations from 15.2% to 17.5% could 

account for the difference. The increased secondary air temperature is the 

most likely explanation for the differences in NO. production. Using the 

values in figure 7.1 determined from measured process gas flows, the 

slope of the line for samples GKF-3.1 and 3.2 is similar to the slope of the 

line for the GKA samples. Such a result is expected lending support to the 

higher value for the GKF-3.2 sample. 

37 
When producing fluxed pellets the Grate-Kiln requires auxiliary burners in 

the preheat zone of the grate. The increased production of NO with the 

increased fuel flow, however, is not as steep as would be expected from 

the kiln burner alone. This observation leads to the conclusion that the 

auxiliary burners do not produce NO as efficiently as the single, larger kiln 

burner. The "secondary air" for the grate burners is leak air plus kiln 

exhaust gas containing 15-16% 02at a temperature 100°F hotter than the 

kiln burner's secondary air. The leak air raises the oxygen content at the 

expense of temperature. Because of the uncertainty regarding the amount 

of leak air and degree of mixing near the burners, it is not possible to state 

with certainty whether the .grate burners' secondary air is hotter or cooler 

than the kiln burner's secondary air. In fact, the nature of the flow pattern 

in the preheat zone hood makes it likely the five burners see significantly 

different environments. It is reasonable, however, to consider that a 

combination of lower oxygen content and lower secondary air temperature 

is the reason why the grate burners produce less NO„ per unit heat input 

than the kiln burner. Lower wall temperatures (the pellet bed especially) 

would induce a greater rate of radiative heat loss from the flames thereby 

lowering the peak flame temperature. This should also contribute to lower 

NO production. 

STRAIGHT-GRATE 

Only a very limited discussion is possible for the Straight-Grate furnace 

because of the difficulties noted in Section 6. The SGF data appear to 

support the statement that the auxiliary burners in the preheat zone of the 

grate produce more NO per unit heat input than the two burners in the 

main combustion chambers. This is most likely due to design differences 

because secondary air temperatures are the same and the radiative 

environments are similar. The two Straight-Grate furnaces were operated 

with significantly different air preheat temperatures. The higher preheat 

temperatures along with the greater use of fuel is most likely responsible 

for the much greater production of NO in the Straight-Grate when 

producing fluxed pellets. 

FURNACE COMPARISONS 

Extrapolating the SGA results to higher heat inputs places the NO 

production rate in the same region as the GKA results. It has not been 

demonstrated that such a large extrapolation is reasonable but the flames 

are qualitatively similar and it may not be an accident that they would 

agree. Air temperatures during the SGA tests were 500-550°F cooler than 

for the GKA tests and, logically, the SGA results should not extrapolate to 

the GKA results. It is reasoned, therefore, that the burners/combustion 

environment for the SGA tests may be more favorable for NO formation 

than the GKA burner/combustion environment. That may be due to the 

38 
larger radiative load on the kiln's flame which would serve to decrease the 

peak flame temperature. 

Extrapolating the GKA results to higher heat inputs places the NO 

production rate in the same region reported by the operators for the 

Straight-Grate producing fluxed pellets. Air preheat temperatures for the 

two machines are 2100-2200°F. The extrapolation, if valid, implies that 

the fuel flow and air preheat temperatures are the dominant variables 

whereas burner and furnace design variations, as they currently exist, are 

much less important. 

Some gas samples taken from the pellet cooler for the furnaces did contain 

some NOR. Cross-flow across the pellet bed was probably the cause for 

this in the Straight-Grate furnaces but the GKA-1 and 2 samples did 

support the findings of a prior laboratory investigation that NO. would not 

be produced in the pellet cooler. 

No discussions regarding SO2or CO have been given in this report. The 

measurements for these species were not consistent and did not appear to 

provide any help in interpreting the NO„ results. Generally, the higher CO 

values should be present if the combustion reactions were not well 

established or, possibly, if the flame is quenched quickly. A sulfur balance 

was beyond the scope of this research but it is obvious that the source of 

sulfur was the pellets. Very low values of sulfur, 100-200 ppm by weight, 

in the green pellets would be sufficient the generate the levels of SO2 

observed. The sulfur appears to be released late in the pellet induration 

stage of the process. 

39 
8. CONCLUSIONS 

A gas sampling survey was conducted on two types of pelletizing furnaces 

producing both fluxed and conventional acid pellets. The survey was able 

to characterize NO formation in the iron ore pelletizing process. 

The pellets alter the gas composition significantly and variations in feed 

rate can be more significant than variations in fuel flow especially when 

fluxed pellets are being produced. 

The pelletizing furnaces surveyed produce 400-700 lb/hr NO2or 2.5 to 4.5 

lb NO2/million BTU of fuel input depending on the type of furnace and 

whether acid or fluxed pellets were being produced. 

Mass flow of NO. increased, generally linearly, with fuel input for any 

furnace. NO. emissions normalized to fuel input did not substantially 

increase with fuel input. 

The Grate-Kiln furnace produces 500-700 lb NO2/hr when producing acid 

pellets and roughly the same when producing fluxed pellets. NO 

generation normalized to fuel input was lower for fluxed pellet production. 

NO. generation normalized to pellet production was higher for fluxed pellet 

production than conventional acid pellet production. 

The Straight-Grate furnace produced 450-480 lb NO2/hr or 4.3 lb 

NO2/million BTU when producing acid pellets but over 900 lb NO2/hr when 

producing fluxed pellets. 

The auxiliary burners in a Grate-Kiln, necessary to produce fluxed pellets, 

produce less NO. per unit heat input than the single, larger kiln burner. 

The kiln burner in a Grate-Kiln produces less NO„ when producing fluxed 

pellets than while producing acid pellets at equivalent heat input. This was 

most likely due to lower secondary air temperatures. 

The auxiliary burners in a Straight-Grate, necessary for the production of 

fluxed pellets, appeared to produce more NO. per unit heat input than the 

main burners. This may have been due to burner design or the radiative 

environment around the flame. 

Formation of NO„ in the pellet cooler of either furnace was not supported 

by the data. 

The NO mass flow relationship with fuel flow for the Straight-Grate 

40 
producing acid pellets appears to extrapolate to the same levels of NO„ 

generation at equivalent fuel flows observed in a Grate-Kiln. The GrateKiln results, in turn, appear to extrapolate to NO„ production rates reported 

for the Straight-Grate producing fluxed pellets. The implication of such 

extrapolations is that the conditions for NOxformation are substantially the 

same for both furnaces despite their radically different designs. 

There is no single sampling location in the Straight-Grate producing fluxed 

pellets that can be used to completely characterize the furnace. 

Flow measurements of process gases at the sampling location should be 

supplemented with flow calculations from the gas analyses and furnace 

operations to verify data consistency. Errors is gas analyses and sampleline air leaks could generally be found and adequately characterized. 

However, CO2values found in stack sampling are too low for the 

technique to be useful. 

41 
REFERENCES 

1. English, A. and Frans, R.D. Developments in Pelletizing. Chapter in 

Agglomeration 77, AIME, N.Y., 1977 pp 3-23. 

2. Koski, R.A. Pelletizing of Various Iron Ore Concentrates and Natural 

Ores as Practiced by the Cleveland-Cliffs Iron Company. Chapter in 

Agglomeration 77, AIME, N.Y., 1977, pp 46-73 

3. Nigro, J.C., Zahl, R.K. Pulverized Coal-Firing Systems for Induration of 

Iron Oxide Pellets. Chapter in Agglomeration 77, AIME, N.Y., 1977, pp 

437-464. 

4. Fluxed Pellet Panel, section in the Proceedings of the 63rd Annual 

Meeting of the Minnesota Section of the AIME/SME, Duluth, MN, January, 

1990, pp 29-57. 

5. Haas, L. A., J. C. Nigro, and R. C. Moe. Use of Oxygen-Enriched Gas 

for the Oxidation of Acid and Fluxed Taconite Pellets. U.S. Bureau of 

Mines RI 9473, 1993, pp 22 

6. Farnam, H.E. Energy Alternatives for the Taconite Industry. 

Proceedings of the Annual Meeting of the Minnesota Section of the 

AIME/SME, Duluth, MN, January 1976, pp. 8-1 to 8-20. 

7. Nigro, J.C. and Zahl, R.K. Preliminary Experiments in Pellet Induration 

using a Coal-fired Cyclone Combuster. Proceedings of the Annual Meeting 

of the Minnesota Section of the AIME/SME, Duluth, MN, January 1976,pp. 

9-1 to 9-47. 

8. Private communication with pelletizing companies and operators 

regarding process operations and the results of emissions tests required by 

the Minnesota Pollution Control Agency. 

9. Haas, L.A., Pojar, M.J., James, M.L. Formation of NO in an Electrical 

and Fuel-Fired Furnace. Pres. at SME/AIME Annual Meeting, Feb. 14-17, 

1994, Albuquerque, New Mexico. 

10. Faulkner, Edward Jr. Guide to Efficient Burner Operation: Gas, Oil & 

Dual Fuel, 1981, pp 156-207. 

11. Haas, L. A., C. F. Anderson, and S. E. Khalafalla. Decomposition of 

Nitric Oxide in a Silent Discharge. Ind. Eng. Chem. Process Des. Dev., 

Vol. 18, No. 1, 1978, pp. 143-147. 

12. Ranzi, E. et al. A Wide Range Modeling Study of Methane Oxidation. 

Combust. Sci. and Tech. 1994, Vol. 96, pp. 279-325. 

13. Miller, J.A., Bowman, C.T. Mechanism and Modeling of Nitrogen 

Chemistry in Combustion. Prog. Energy Combust. Sci., 1989, Vol. 15, pp. 

287-338. 

14. Bowman, C. T. Control of Combustion-Generated Nitrogen Oxide 

Emission: Technology Driven by Regulation. Twenty-Fourth Symposium 

(International) on Combustion/The Combustion Institute, 1992, pp. 859-

878. 

15. Burner Retrofits Reduce Brewery Emissions. Chemical Engineering, 

April 1993, pp. 177. 

42 
16. Lilleheie, N.I., et.al. Modeling Chemical Reactions - Development and 

Test of Reduced Chemical Kinetic Mechanism for Combustion of Methane. 

DE92-70389, NTIS, Wash.D.C., May 1991, pp. 132. 

17. Correa, S.M. A Review of NO„ Formation Under Gas-Turbine 

Combustion Conditions. Combust. Sci. and Tech., 1992, Vol. 87, pp. 

329-362 

18. Silver, R. G., S. E. Swayer, and J. C. Summers, Editors. Catalytic 

Control of Air Pollution: Mobile and Stationary Sources. ACS, Washington, 

DC. 1992, pp. 1-113. 

19. Vatsky, J. and E. S. Schindler. Industrial and Utility Boiler Low NO 

Control Update, PB 89-139695, 1989, p. 15-2. 

20. Meersman, T. MPCA Says Proposed Emission Fees Are Too Low in 

the Dakotas. Minneapolis Star and Tribune, August 25, 1993, p. 6B. 

21. Swayer, R. F. The Formation and Destruction of Pollution in 

Combustion Processes: Clearing the Air on the Role of Combustion 

Research. Eighteenth Symposium (International) on Combustion. The 

Combustion Institute, 1981, pp. 1-22. 

22. Nitrogen Oxide Control for Stationary Combustion Sources. 

EPA/625/5-86/020, July 1986, 49 pp. 

23. Sourcebook: NO. Control Technology Data, EPA/600/S2-91/029, 

August 1991, pp 9. 

24. Seeley, R. S. Clean Air Act Amendments Spawn Lively Air Pollution 

Equipment Market. ES&T Environmental Buyers' Guide Edition, ACS, 

1993, pp. 14-17. 

25. Nielsen, P. B. and 0. L. Jepson. An Overview of the Formation of 

SO. and NO in Various Pyroprocessing Systems. IEEE Trans. on Industry 

Applications, v. 27, no. 3, May/June 1991, pp. 431-439. 

43 
TABLES 
Table 2.1 Weather data for the field study - Hibbing, MN airport 

Date 

yyyymmdd 

Air 

Temp 

F 

WetB DewP 

Temp Temp 

F F 

Rel.H 

(min) 

pct. 

Rel.H 

(max) 

pct. 

Wind 

Speed 

mph 

Wind SeaLev 

Direct. Press. 

deg. mb 

Solar Pot 

Radiation 

MJ/sq m 

Evap 

in 

Local 

Pressure 

inHg 

Moisture 

in Air 

vol Tract. 

19930928 43 40 36 68 89 10 336 1018 7.4 0.05 28.700 0.00737 

19930929 38 33 27 37 85 9 313 1026 17.9 0.09 28.937 0.00509 

19930930 0 0 0 0 0 0 0 0 16.2 0.16 ND ND 

19931001 38 33 26 50 86 13 315 1007 8.6 0.07 28.374 0.00459 

19931002 31 27 20 40 85 11 277 1017 15.6 0.08 28.670 0.00358 

19931003 49 43 38 40 85 11 297 1007 12.7 0.13 28.374 0.00807 

19931004 39 34 26 35 78 11 316 1016 16.6 0.10 28.641 0.00455 

19931005 41 35 27 33 83 9 178 1021 14.0 0.10 28.789 0.00512 

19931006 56 48 43 35 85 8 205 1011 15.8 0.12 28.492 0.00977 

19931007 43 40 35 61 82 12 40 1019 6.2 0.05 28.729 0.00709 

19931008 35 31 25 46 85 12 7 1022 10.8 0.07 28.818 0.00452 

19931018 38 35 32 62 89 2 284 1018 6.2 0.00 28.700 0.00628 

19931019 40 38 35 71 89 6 166 1019 7.2 0.01 28.729 0.00709 

19931020 43 41 37 69 89 10 267 1014 4.7 0.02 28.581 0.00771 

19931021 34 31 25 59 79 12 306 1016 5.4 0.04 28.641 0.00455 

19931022 38 32 25 31 87 6 204 1024 13.4 0.08 28.877 0.00451 

19931129 15 14 11 71 86 6 351 1024 2.6 0.00 28.877 0.00222 

19931130 0 0 0 0 0 0 0 0 2.9 0.01 ND ND 

19931201 26 25 22 75 91 12 174 1018 2.5 0.00 28.700 0.00454 

19931202 30 29 27 83 91 6 291 1015 1.5 -0.01 28.611 0.00515 

19940420 39 31 16 27 68 10 331 1025 19.5 0.13 28.907 0.00279 

19940421 40 32 18 21 86 3 22 1026 21.0 0.10 28.937 0.00355 
Table 2.2 Results of a sensitivity analysis for a +5% change in the indicated 

parameters using the data set obtained on Oct. 21, 1993. 

Parameter 

changed 

by +5% 

Resulting 

change in 

NO,, mass 

flow 

Resulting 

change in 

NO,, flow 

per MMBTU 

Parameter 

changed 

by + 5% 

Resulting 

change in 

NO,, mass 

flow 

Resulting 

change in 

NO,, flow 

per MMBTU 

Pellet feed + 2.22 + 2.22 02 meas. +4.03 +4.03 

Pellet 

moisture 

+ 0.26 + 0.26 CO2meas. -3.83 -3.83 

Pellet 

oxidation 

+ 0.30 +0.30 NO,, meas. +5.00 +5.00 

Pellet 

calcination 

+1.48 + 1.48 All 

combined 

+12.3 +7.4 

Fuel flow + 2.79 -2.11 Maximum +25.1 +19.2 
Table 3.1 Average gas analyses for the Grate-Kiln producin 

acid pellets 

Date 

Sample ID 

Time 

Period 

Statistic NOx 

ppm (wet) 

_ 

SO2 

ppm (wet) 

CO 

ppm (dry) 

CO2 

% (dry) 

02 

% (dry) 

10/18/93 

GKA-6a Samples 44 44 47 50 48 

11:27 Mean 231.72 52.823 8.897 1.437 17.662 

to StdDev 18.35 4.36 1.79 0.03 0.11 

14:00 CoefVar,% 7.92 8.25 20.15 2.31 0.61 

10/19/93 

GKA-5 Samples 18 20 19 19 19 

13:29 Mean 309.72 121.000 8.895 1.889 15.805 

to StdDev 7.76 6.41 1.36 0.02 0.26 

15:15 CoefVar,% 2.51 5.30 15.29 1.11 1.64 

10/20/93 

GKA-3 Samples 58 57 61 58 . 61 

10:24 Mean 526.41 32.467 0.307 1.485 17.469 

to StdDev 42.09 3.90 0.34 0.13 0.33 

13:27 CoefVar,% 8.00 12.00 112.09 8.79 1.92 

10/21/93 

GKA-6b.1 Samples 36 36 31 37 37 

11:46 Mean 212.63 46.944 7.823 1.140 17.136 

to StdDev 16.00 2.40 2.71 0.07 0.22 

13:34 CoefVar,% 6.68 5.07 35.90 5.53 1.30 

10/21/93 

GKA-6b.2 Samples 53 52 52 53 53 

13:55 Mean 195.59 45.895 9.653 1.043 17.426 

to StdDev 11.88 2.68 1.75 0.05 0.15 

16:31 CoefVar,% 6.44 5.74 17.57 4.92 0.84 

10/.21/93 

GKA-6b.3 Samples 29 29 29 29 29 

13:55 Mean 198.04 45.407 9.641 1.049 17.346 

to StdDev 12.25 2.82 1.54 0.06 0.13 

15:19 CoefVar,% 28.42 24.97 33.74 28.18 13.89 

10/22/93 

GKA-6c Samples 41 41 43 41 42 

10:28 Mean 199.19 43.663 3.053 0.971 18.622 

to StdDev 10.89 2.59 1.49 0.03 0.15 

12:34 CoefVar,% 5.67 5.54 94.19 3.99 1.10 

utliers removed 
Table 3.2: Feed & product chemistry for the Grate-Kiln producing acid pellets 

Date 

Green Pellets d basis) 1 Fired Pellets 

Fe Si02 CaO MgO, C, S Fe+2 Fe Si02 CaO, MgO C S Fe+2 Oxidized Calcined Desulfurized 

wt.% wt.% wt.% wt.% wt.% ppm wt.% wt.% wt.% wt.% wt.% wt.% ppm wt.% pct sot pct 

10/18/93 66.61 5.49 0.43 0.29 0.33 143 22.64 65.43 5.28 0.51 0.30 0.023 10 0.50 97.71 92.90 92.88 

10/19/93 66.64 5.61 0.38 0.33_ 0.31 146 21.39 63.35 5.42 0.46, 0.34 0.026 10 0.38 98.20 91.18 92.79 

10/20/93 69.60 5.97 0.28 0.36 0.29 121 22.04 64.71 5.65 0.32 0.35 0.019 10 0.31 

k 

98.56 92.95 91.11 

10/21/93 66.74 5.53 0.36 0.34 0.29 160 22.47 65.49 5.44 0.27 0.33 0.012 10 0.38 98.26 95.78 93.63 

10/22/93 67.00 5.46 0.31 0.33 0.27 159 22.45 65.56 5.35 0.33 0.33' 0.011 10 0.44 97.99 95.84 93.57 

Average 1 67.32 5.61 0.35 0.33 0.30 146 22.20 64.91 5A3 0.38 

South 

0.33 

preheat 

 0.018 

fan 

10 

cyclone 

0.401 98.14 

dust 

93.73 92.80 

09/16/93 64.44 7.63 0.4 0.43 ND ND 7.87 63.36 ND 

111•1=11 

ND 

North preheat fan cyclone dust 

09/16/93 I 65.11 6.58 0.4_, 0.41 ND, ND, 8.62 60.28 ND ND 

Oxidation = (1-(3*Fe++/Fe))*100 

Calcination: By means of ratios of C/Fe 

Desulfurization: By means of ratios of S/Fe 

Average used for green feed on 9/16/93 
Table 3.3: Summary of measurements for the Grate-Kiln producing acid pellets 

Date 

Sample 

Period 

H:M - H:M 

Pellet 

Feed 

It/hr 

Pellet 

Moisture 

wt % 

Kiln 

Fuel 

mcfh 

Grate 

Fuel 

mcfh 

P1 

(max 02) 

mcfh 

P2 

(max CO2) 

mcfh 

P3 

(max H2O) 

mcfh 

Gas 

Sample 

I.D. 

Gas Analyses Estimated 

H2O vapor 

v%(wet) 

Gas 

Density 

Ibm/cf 

CO2 

v% (dry) 

02 

v% (dry) 

NOx 

ppm (wet) 

10/18/93 11:25 - 14:00 482.8 9.5 155.5 0 379.4 97.3 2201.1 GKA-6a 1.437 17.662 231.720 8 0.0719 

10/19/93 13:29 - 15:15 482.8 9.5 154.6 0 360.2 89.7 2201.1 GKA-5 1.889 15.805 309.720 2 0.0736 

10/20/93 10:23 - 13:26 499.6 9.5 149.6 0 385.5 88.6 2277.8 GKA-3 1.485 17.469 526.410 3 0.0733 

10/21/93 11:50 -13:29 477.5 9.5 150.6 0 374.5 87.2 2176.9 GKA-6b.1 1.140 17.136 212.630 8 0.0717 

10/21/93 13:55 - 16:31 460 9.5 140.9 0 360.8 84.0 2097.3 GKA-6b.2 1.040 17.430 195.590 8 0.0717 

10/21/93 13:55 - 15:19 510.6 9.5 139.7 0 400.5 93.3 2328.0 GKA-6b.3 1.049 17.350 198.040 8 0.0717 

10/22/93 10:29 -12:32 435.5 9.5 135.6 0 340.3 74.1 1985.7 GKA-6c 0.971 18.622 199.190 8 0.0718 
Table 3.4: Summary of results for the Grate-Kiln producing acid pellets 

Gas Sampling 

Location 

Gas 

Sample 

I.D. 

Kiln 

Fuel 

mcfh 

Grate 

Fuel 

mcfh 

P1 

(actual) 

mcfh 

P2 

(actual) 

mcfh 

P3 

(actual) 

mcfh 

Gas Analyses Process Gas Flow Measured Process Gas Flow Calculated 

CO2 

v% (dry) 

02 

v% (dry) 

NOx 

_ppm (wet) 

Gas Flow 

mcfh 

NOx 

lb/hr 

NOx 

lb/MMBTU 

Gas Flow 

mcfh 

NOx 

lb/hr 

NOx 

lb/MMBTU 

Waste Gas Fan GKA-6a 155.5 0.0 379.4 97.3 2201.1 1.437 17.662 231.720 25265 692 4.452 20638 566 3.637 

PreHeat Fan GKA-5 154.6 0.0 360.2 , 89.7 0.0 1.889 15.805 309.720 14299 524 3.388 13066 479 3.095 

Kiln Exhaust GKA-3 149.6 0.0 154.2 4.4 0.0 1.485 17.469 526.410 10235 637 4.259 11063 689 4.604 

Waste Gas Fan GKA-6b.1 150.6 0.0 374.5 87.2 2176.9 1.140 17.136 212.630 25391 638 4.239 22899 576 3.823 

Waste Gas Fan GKA-6b.2 140.9 0.0 360.8 84.0 2097.3 1.040 17.430 195.590 23665 547 3.885 23675 548 3.887 

Waste Gas Fan GKA-6b.3 139.7 0.0 400.5 93.3 2328.0 1.049 17.350 198.040 24024 563 4.028 24461 573 4.101 

Waste Gas Fan GKA-6c 135.6 0.0 340.3 74.1 1985.7 0.971 18.622 199.190 21826 514 3.792 24747 583 4.299 
Table 4.1 Average gas analyses for the Straight-Grate producing 

acid pellets. 

Date 

Sample ID 

Time Period 

Statistic SO2 

ppm (wet) 

CO 

ppm (dry) 

NOx 

ppm (wet) 

02 

 pct (dry) 

CO2 

pct (dry) 

Samples 42. 41 42 42 42 

04/20/94 Mean 8.027 0.775 43.13 20.464 0.269 

SGA-VVB16 StdDev 1.05 0.36 6.57 0.08 0.04 

12:35 - 13:50 CoefVar,% 13.14 47.04 15.24 0.39 13.85 

Samples 5 8 7 8 6' 

04/21/94 Mean 5.780 < 1.0 629.64 17.240 2.318 

SGA-WB18.1 StdDev 0.29 ND 47.31 0.17 0.09 

9:51 - 9:59 CoefVar,% 5.06 ND 7.51 1.00 3.69 

Samples 20 27 24 25' 27 

04/21/94 Mean 5.965 < 1 713.13 17.142 2.372 

SGA-VVB18.2 StdDev 0.31 ND 36.92 0.13 0.07 

10:00 - 10:29 CoefVar,% 5.20 ND 5.18 0.76 2.88 

Samples 27 27 27 25 24' 

04/21/94 Mean 5.315 < 1 637.60 17.293 2.337 

SGA-VVB18.3 StdDev 0.36 ND 36.57 0.15 0.07 

10:30 - 10:59 CoefVar,% 6.77 ND 5.74 0.86 3.04 

Samples 28 28 28 27 27 

04/21/94 Mean 5.136 < 1 648.93 17.136 2.433 

SGA-WB18.4 StdDev 0.26 ND 40.29 0.13 0.07 

11:00 - 11:29 CoefVar,% 5.13 ND 6.21 0.76 2.82 

Samples 25 25' 24 24 ' 25 

04/21/94 Mean 5.112 < 1 588.88 17.196 2.417 

SGA-WB18.5 StdDev 0.41 ND 39.81 0.13 0.07 

11:30 - 11:59 CoefVar,% 8.00 ND 6.76 0.76 2.93 

Samples 26 26 26 22 22 

04/21/94 Mean 4.765 < 1 609.86 17.136 2.469 

SGA-WB18.6 StdDev 0.33 ND 51.73 0.12 0.06 

12:00 - 12:29 CoefVar,% 6.96 ND 8.48 0.73 2.54 

Samples 28 28 28 27 28 

04/21/94 Mean 4.850 < 1 657.99 17.286 2.385 

SGA-WB18.7 StdDev 0.32 ND 54.54 0.13 0.07 

12:30 - 12:59 CoefVar,% 6.53 ND 8.29 0.73 2.82 

Samples 25 26 26 26 26 

04/21/94 Mean 4.760 < 1 664.35 17.278 2.396 

SGA-WB18.8 StdDev 0.28 ND 40.61 0.12 0.06 

13:00 -13:29 CoefVar,% 5.85 ND 6.11 0.71 2.62 

Samples 18 18 17 18' 18 

04/21/94 Mean 4.639 < 1 674.46 17.248 2.404 

SGA-WB18.9 StdDev 0.20 ND 27.38 0.12 0.06 

13:30 - 13:50 CoefVar,% 4.32 ND 4.06 0.68 2.52 

Outliers removed 
Table 4.2: Feed & product chemistry for the Straight-Grate producing acid pellets 

Date 

Green Pellets (dry basis Fired Pellets 

Fe S102 CaO MgO C S Fe+2 Fe 8102 CaO MgO C S Fe+2 Oxidized Calcined Desulfurized 

4 wt.% wt.% wt.% wt.% wt.% ppm wt.% wt.% wt.% wt.% wt.% wt.% ppm wt.% pct pct pct _ 

04/21/94 73.90 5.78 0.22 0.23 0.32 ND 22.30 65.00 0.020 0.40 98.15 92.89 ND 
Table 4.3: Summary of measurements for the Straight-Grate producing acid pellets. 

Date 

Sample 

Period 

H:M - H:M 

Pellet 

Feed 

It/hr 

Pellet 

Moisture 

wt % 

South 

Fuel 

mcfh 

North 

Fuel 

mcfh 

P1 

(max 02) 

mcfh 

P2 

(max CO2) 

mcfh 

P3 

(max H2O) 

mcfh 

Gas 

Sample 

I.D. 

Gas Analyses Estimated 

H2O vapor 

v%(wet) 

Gas 

Density 

Ibm/cf 

CO2 

v% (dry) 

02 

v% (dry) 

NOx 

ppm (wet) 

04/20/94 12:35 - 13:50 382.5 9.25 42.0 68.0 298.2 75.0 1698.1 SGA-WB16 0.269 20.464 43.13 0.6 0.0737 

04/21/94 09:30 - 10:00 383.4 9.25 41.0 68.7 298.9 75.2 1702.1 SGA-W618.1 2.318 17.240 629.64 4.5 0.0732 

04/21/94 10:00 - 10:30 383.4 9.25 39.5 66.7 298.9 75.2 1702.1 SGA-VVB18.2 2.372 17.142 713.13 4.6 0.0732 

04/21/94 10:30 - 11:00 383.4 9.25 38.3 70.5 298.9 75.2 1702.1 SGA-WB18.3 2.337 17.293 637.60 4.5 0.0732 

04/21/94 11:00 - 11:30 383.4 9.25 36.6 70.8 298.9 75.2 1702.1 SGA-WB18.4 2.433 17.136 648.93 4.6 0.0732 

04/21/94 11:30 - 12:00 382.5 9.25 32.3 68.6 298.2 75.0 1698.1 SGA-WB18.5 2.417 17.196 588.88 4.5 0.0732 

04/21/94 12:00 - 12:30 381.6 9.25 33.8 73.5 297.5 ... 74.8 1694.1 SGA-WB18.6 2.469 17.136 609.86 4.7 0.0732 

04/21/94 12:30 - 13:00 382.5 9.25 36.0 69.9 298.2 75.0 1698.1 SGA-WB18.7 2.385 17.286 657.99 4.5 0.0732 

04/21/94 13:00 - 13:30 381.6 9.25 39.1 70.8 297.5 74.8 1694.1 SGA-WB18.8 2.396 17.278 664.35 4.6 0.0732 

04/21/94 13:30 - 13:50 383.4 9.25 36.7 67.2 298.9 75.2 1702.1 SGA-WB18.9 2.404 17.248 674.46 4.6 0.0732 

Low primary air includes the period 11:00 to 12:30 
Table 4.4: Summary of results for the Straight-Grate producing acid pellets. 

Gas Sampling 

Location 

Gas 

Sample 

I.D. 

South 

Fuel 

mcfh 

North 

Fuel 

mcfh 

P1 

(actual) 

mcfh 

P2 

(actual) 

mcfh 

P3 

(actual) 

mcfh 

Gas Analyses Process Gas Flow Calculated North Chamber Estimated 

CO2 

v% (dry)_ 

02 

v% (dry) 

NOx 

ppm (wet) 

Gas Flow 

mcfh 

NOx 

Ibm/hr 

NOx 

IbmIMMBTU 

Gas Flow 

mcfh 

NOx 

Ibm/hr 

NOx 

IbmIMMBTU 

WindBox 16 Hood SGA-WB16 42.0 68.0 22.9 1.7 0.0 0.269 20.464 43.130 1977 10.08 3.69 ND ND ND 

Windbox 18 Hood SGA-WB18.1 41.0 68.7 22.9 1.7 0.0 2.318 17.240 629.640 2069 154.05 3.76 ND 317 4.62 

Windbox 18 Hood SGA-WB18.2 39.5 66.7 22.9 1.7 0.0 2.372 17.142 713.130 1956 164.95 4.18. ND 306 4.59 

Windbox 18 Hood SGA-WB18.3 38.3 70.5 22.9 1.7 0.0 2.337 17.293 637.600 1935 145.91 3.81 ND 328 4.65 

Windbox 18 Hood SGA-W818.4 36.6 70.8 22.9 1.7 0.0 2.433 17.136 648.930 1789 137.27 3.75 ND 330 4.65 

Windbox 18 Hood SGA-WB18.5 32.3 68.6 22.9 1.7 0.0 2.417 17.196 588.880 1608 111.96 3.47 ND 317 4.62 

Windbox 18 Hood SGA-WB18.6 33.8 .., 73.5 22.8 1.7 0.0 2.469 17.136 609.860 1645 118.61 3.51 ND 345 4.69 

Windbox 18 Hood SGA-W918.7 36.0 69.9 22.9 1.7 0.0 2.385 17.286 657.990 1799 140.02 3.89 ND 324 4.64 ... 

Windbox 18 Hood SGA-WB18.8 39.1 70.8 22.8 1.7 0.0 2.396 17.278 664.350 1934 151.93 3.89 ND 330 4.65 

WindBox 18 Hood SGA-WB18.9 36.7 67.2 22.9 1.7 0.0 2.404 17.248 674.460 1818 _ 145.01 3.95 ND 309 4.60 

Low primary air includes the period 11:00 to 12:30 

North Chamber Estimate: NOx (Ibm/hr) = -77.33987 5.74875 *Fuel (mcfh) 
Table 5.1 Average gas analyses for the Grate-Kiln producing 

fluxed pellets 

Date 

Sample ID 

Time Period 

Statistic NOx 

ppm (wet) 

SO2 

ppm (wet) 

CO 

ppm (dry) 

02 

% (dry) 

CO2 

% (dry) 

Samples 35 35 0 36 0 

10/07/93 Mean 4.21 274.14 ND 19.024 ND 

GKF-1 StdDev 0.25 90.36 ND 0.202 ND 

14:06 - 17:00 CoefVar,% 5.87 32.96 ND 1.059 ND 

Samples 4 4 4 4 4 

10/08/93 Mean 3.69 1.25 0.40 20.575 0.040 

GKF-2 StdDev 0.54 2.17 0.64 0.043 0.000 

09:45 - 10:20 CoefVar,% 14.68 173.21 159.10 0.210 0.000 

Samples 34 31 20 34 31 

10/06/93 Mean 501.18 17526 0.25 15.288 2.435 

GKF-3.1 StdDev 49.63 20.80 0.08 0.314 0.143 

13:05 -16:00 CoefVar,% 9.90 11.87 32.82 2.055 5.858 

Samples 5 6 6 5 6' 

10/06/93 Mean 428.00 151.67 0.12 15.300 2.383 

GKF-3.2 StdDev 27.86 5.53 0.04 0.395 0.157 

16:05 - 16:30 CoefVar,% 6.51 3.64 31.94 2.581 6.597 

Samples y 8 8' 8 8 8 

10/05/93 Mean 743.75 259.50 2.50 11.900 4.481 

GKF-4.1 StdDev 33.14 22.84 1.41 0.260 0.143 

11:45 - 12:45 CoefVar,% 4.46 8.80 56.57 2.183 3.202 

Samples 10 10 10 10 9 

10/05/93 Mean 781.00 242.40 16.60 11.490 4.900 

GKF-4.2 StdDev 24.27 13.15 5.41 0.439 0.271 

13:00 - 14:32 CoefVar,% 3.11 5.42 32.57 3.822 5.527 

Samples 17 17 17 17' 17 

10/04/93 Mean 397.06 112.35 33.18 15.165 4.292 

GKF-5.1 StdDev 15.44 13.11 4.26 0.185 0.143 

13:00 - 15:05 CoefVar,% 3.89 11.67 12.84 1.217 3.323 

Samples 5 5 5 5 3 

10/04/93 Mean 369.00 89.00 18.60 15.740 4.053 

GKF-5.2 StdDev 6.63 3.74 0.80 0.174 0.038 

15:10 - 15:30 CoefVar,% 1.80 4.20 4.30 1.108 0.930 

Corrected for drift Samples 27 6 6 28 26 

09/28/93 Mean 90.176 2.22 3.36 19.462 1.308 

GKF-6a StdDev 8.39 0.57 1.19 0.22 0.16 

13:05 - 18:30 CoefVar,% 9.30 25.53 35.50 1.14 12.40 

Samples 2 3 3 3 3 

09/30/93 Mean 238.50 19.33 19.33 16.933 3.133 

GKF-6b.1 StdDev 3.50 3.09 0.47 0.170 0.085 

11:42 -11:55 CoefVar,% 1.47 15.99 2.44 1.004 2.712 

Samples 31 31 30 29 31' 

09/30/93 Mean 247.58 27.39 22.92 16.728 3.246 

GKF-6b.2 StdDev 12.50 10.63 3.22 0.069 0.043 

12:00 - 14:30 CoefVar,% 5.05 38.81 14.06 0.412 1.336 

Samples 4 4 4 4 4 

09/30/93 Mean 258.75 27.75 25.00 16.925 3.088 

GKF-6b.3 StdDev 4.15 7.95 1.41 0.043 0.013 

14:35 - 15:00 CoefVar,% 1.60 28.65 5.66 0.256 0.421 

Outliers removed 
Table 5.2: Feed & product chemistry for the Grate-Kiln producing fluxed pellets 

Date 

Green Pellets (dry basis) Fired Pellets 

Fe Si02 CaO MgO C S Fe+2 Fe Si02 CaO MgO C S Fe+2 Oxidized Calcined Desulfurized. 

wt.% wt.% wt.% wt.% wt.% ppm wt.% wt.% wt.% wt.% wt.% wt.% ppm wt.% pct pct pct 

09/28/93 62.27 4.11 . 3.47 1.07 1.32 162 20.48 63.35 4.37 3.6 1.1 0.074 30 0.25 98.82 94.49 81.80 . 

09/30/93 62.61 4.11 3.44 1.05 1.20 115 20.80 63.79 4.04 3.55 1.06 0.060 19 0.63 97.04 95.09 83.78 

10/04/93 63.08 3.98 3.25 1.02 1.20 148 21.68 63.96 4.05 3.36 1.02 0.059 16 0.50 97.65 95.15 89.34 . 

10/05/93 62.66 3.99 3.60 1.12 1.23 162 21.49 63.64 4.02 3.65 1.13 0.063 28 0.69 96.75 94.96 82.98 

10/06/93 62.93 4.01 3.45 1.07 1.10 143 21.09 63.84 4.00 3.47 1.06 0.058 20 0.94 95.58 94.80 86.21 

10/07/93 62.55 4.09 3.49 1.09 1.21 153 20.40 63.67 4.11 3.60 1.09 0.053 24 0.88 95.85 95.70 84.59 

10/08/93 62.67 4.19 3.46 1.07 1.17 162 21.20 63.71 4.25 3.54 1.07 0.058 20 0.38 98.21 95.12 87.86 

Avera • e 62.75 4.06 3.45 1.07 1.19 147 21.11 63.77 4.08 3.53 1.07 0.06 21 0.67 96.85 95.14 85.79 

, South preheat fan cyclone dust 

09/29/93 62.35 I 4.09 1 3.55 1 1.11 1 1.24 1 146 I 20.53 62.9 I 4.5 I 3.35 [1.211 0.59 11990 1 9.7 I 53.74 I 52.84 I Conc. 

.. 

North preheat fan cclone dust 

09/29/93 62.35 4.09 3.55 1.11 1 1.24 146 l 20.53 4 63.17 4.01 1 3.07 Ey 1.1 0.541 453] 9.7 1 53.93 I 57.02 Conc. 

Oxidation = (1-(3*Fe++/Fe))*100 

Calcination: By means of ratios of C/Fe 

Desulfurization: By means of ratios of S/Fe 
Table 5.3: Summary of measurements for the Grate-Kiln producing fluxed pellets 

Date 

Sample 

Period 

H:M - H:M 

Pellet 

Feed 

It/hr 

Pellet 

Moisture 

wt % 

Kiln 

Fuel 

mcfh 

Grate 

Fuel 

mcfh 

P1 

(max 02) 

mcfh 

P2 

(max CO2) 

mcfh 

P3 

(max H2O) 

mcfh 

Gas 

Sample 

I.D. 

Gas Analyses Estimated 

H2O vapor 

v%(wet) 

Gas 

Density 

Ibm/cf 

CO2 

v% (dry) 

02 

v% (dry) 

NOx 

ppm (wet) 

09/28193 13:05 - 18:30 459.0 9.5 140.0 90.0 330.0 376.5 2093 GKF-6a 1.308 19.462 90.176 5 0.0728 

09/30/93 11:42 - 11:55 459.0 9.5 150.0 70.0 329.1 344.4 , 2093 GKF-6b.1 3.133 16.933 238.50 10 0.0719 

09/30/93 12:00 - 14:30 459.0 9.5 140.0 90.0 329.1 344.4 2093 GKF-6b.2 3.246 16.728 247.58 10 0.0719 

09/30/93 14:35 - 15:00 459.0 9.5 140.0 81.0 329.1 344.4 2093 GKF-6b.3 3.088 16.925 258.75 10 0.0719 

10/04/93 13:00 - 15:07 459.0 9.5 160.0 70.0 345.2 344.6 2093 GKF-5.1 4.292 15.165 397.06 7 0.0730 

10/04/93 15:07 - 15;30 459.0 9.5 143.0 90.0 345.2 344.6 2093 GKF-5.2 4.053 15.740 369.00 7 0.0730 

10/05/93 11:42 - 12:47 445.1 9.5 166.6 70.9 328.7 341.8 2029 GKF-4.1 4.481 11.900 743.75 8 0.0725 

10/05/93 12:57 - 14:47 443.5 9.5 158.3 90.3 327.5 340.6 2022 GKF-4.2 4.900 11.490 781.00 8 0.0727 

10/06/93 13:07 - 15:57 443.5 9.5 147.9 89.9 317.6 304.1 2022 GKF-3.1 2.435 15.288 501.18 5 0.0729 

10/06/93 16:07 - 16:32 443.1 9.5 157.8 71.8 317.3 303.9 2020 GKF-3.2 2.383 15.300 428.00 5 0.0729 

10/07/93 14:37 - 16:57 443.9 9.5 136.5 90.7 „ 308.3 338.0 2024 GKF-1 ND 19.024 4.21 0.4 0.0735 

10/08/93 09:47 - 10:17 444.0 9.5 179.1 70.3 328.4 324.9 2024 GKF-2 0.040 20.575 3.69 0.4 0.0737 

Sample GKF-6a was corrected for drift and contains a large sample-line air leak. 
Table 5.4: Summary of results for the Grate-Kiln producing fluxed pellets 

Gas Sampling 

Location 

Gas 

Sample 

I.D. 

Kiln 

Fuel 

mcfh 

Grate 

Fuel 

mcfh 

P1 

(actual) 

mcfh 

P2 

(actual) 

mcfh 

P3 

(actual) 

mcfh 

Gas Analyses Process Gas Flow Measured Process Gas Flow Calculated 

CO2 

v% (dry) 

02 

v% (dryLppm 

NOx 

(wet) 

Gas Flow 

mcfh 

NOx 

Ibm/hr 

NOx 

IbmIMMBTU 

Gas Flow 

mcfh 

NOx 

Ibm/hr 

 NOx 

Ibm!MMBTU 

Waste Gas Fan GKF-6a 140.0 90.0 330.0 376.5 2092.8 1.308 19.462 90.176 ND ND ND 50539 539 2.343 

Waste Gas Fan GKF-6b.1 150.0 70.0 329.1 344.4 2092.8 3.133 16.933 238.50 24775 699 3.176 20794 587 2.686 

Waste Gas Fan GKF-6b.2 140.0 90.0 329.1 344.4 2092.8 3.246 16.728 247.58 21857 640 2.782 20457 599 2.604 

Waste Gas Fan GKF-6b.3 140.0 81.0 329.1 344.4 2092.8 3.088 16.925 258.75 21848 669 3.025 21042 644 2.913 

PreHeat Fan. GKF-5.1 160.0 70.0 • 345.2 344.6 0.0 4.292 15.165 397.06 14958 702 3.178 13648 641 2.900 

PreHeat Fan GKF-5.2 143.0 90.0 345.2 344.6 0.0 4.053 15.740 369.00 12342 539 2.404 14699 641 2.864 

PreHeat Hood GKF-4.1 166.6 70.9 131.5 17.1 0.0 4.481 11.900 743.75 ND ND ND ND ND ND 

PreHeat Hood GKF-4.2 158.3 90.3 131.0 17.0 0.0 4.900 11.490 781.00 ND ND ND ND ND ND 

Kiln Exhaust GKF-3.1 147.9 89.9 127.0 15.2 0.0 2.435 15.288 501.18 6750 400 2.705 7040 417 2.822 

Kiln Exhaust GKF-3.2 157.8 71.8 126.9 15.2 0.0 2.383 15.300 428.00 9379 475 3.008 7568 383 2.427 

Cooler Gas (kiln) GKF-1 136.5 90.7 107.9 16.9 0.0 ND 19.024 4.21 ND ND ND ND ND ND 

Cooler Gas (duct) GKF-2 179.1 70.3 114.9 _ 16.2 0.0 0.040 20.575 3.69 ND ND ND ND ND ND 

Sample GKF-6a was corrected for drift and contains a large sample-line air leak. 
Table 6.1 Average gas analyses for the Straight-Grate 

producing fluxed pellets 

Date 

Sample ID 

Sample 

Period 

Statistic SO2 

ppm(wet) 

CO 

ppm(dry) 

NOx 

ppm(wet) 

02 

pct(dry) 

CO2 

pct(dry) 

11/29/93 

WB 6 Samples 32 34 33 33 8 

13:51 Mean 5.352 < 3 48.51 20.403 0.544 

to Std Dev 0.92 ND 2.99 0.06 0.04 

15:32 CoefVar, % 17.19 ND 6.17 0.32 8.12 

11/30/93 ' 

WB 10 Samples 20 0 20 19 8 

15:56 Mean 34.824 ND 176.14 18.143 2.181 

to Std Dev 2.75 ND 12.01 0.13 0.08 

16:56 CoefVar, % 7.90 ND 6.82 0.72 3.79 

12/01/93 

WB 12 Samples 40 0 41 42 18 

13:54 Mean 7.404 ND 611.11 17.553 2.483 

to Std Dev 1.27 ND 121.86 0.50 0.44 

15:57 CoefVar, % 17.18 ND 19.94 2.86 17.62 

12/02/93 

WB 26 Samples 27 0 27 25 7 

10:42 Mean 14.943 ND 13.97 20.758 0.046 

to Std Dev 9.94 ND 3.29 0.11 0.01 

12:00 CoefVar, % 66.52 ND 23.52 0.53 15.93 

Outliers Removed 
Table 6.2: Feed & product chemistry for the Straight-Grate producing fluxed pellets 

Date 

Green Pellets (dry basis) Fired Pellets 

Fe Si02 CaO MgO est.0 S Fe+2 Fe Si02 CaO MgO est.0 S Fe+2 Oxidized Calcined 

wt.% wt.% wt.% wt.% wt.% ppm wt.% wt.% wt.% wt.% wt.% wt.% ppm wt.% pct pct 

11/29/93 61.78 4.17 4.14 1.53 1.50 ND 20.94 62.96 4.18 4.68 1.51 0.012 ND 1.32 93.71 99.21 

11/30/93 61.83 4.18 4.07 1.53 1.46 ND 20.73 62.97 4.16 4.52 1.45 0.012 ND 1.07 94.90 99.19 

12/01/93 65.50 5.78 3.92 1.24 1.35 ND 20.84 ND ND ND ND ND ND ND 94.31 99.20 

Average 63.04 4.71_ 4.04 1.43 1.44 ND 20.84 41.98_ 2.78 3.07 0.99 0.01 ND 0.80 94.31 99.20 

Oxidation = (1-(3*Fe++/Fe)).`100 

Estimated C in Green Pellets: From CaO + MgO and 0.01 of Fe as FeCO3 

Carbon measured on grab-sample taken on 12/01/93 but average oxidation & calcination assumed 

Calcination: By means of ratios of C/Fe 
Table 6.3: Summary of measurements & estimates for the Straight-Grate producing fluxed pellets. 

Date 

Sample 

Period 

H:M - H:M 

Pellet 

Feed 

It/hr 

Pellet 

Moisture 

wt % 

Est.A 

Fuel 

mcfh 

Est.B 

Fuel 

mcfh 

P1 

(max 02) 

mcfh 

P2 

(max CO2) 

mcfh 

P3 

(max H20) 

mcfh 

Gas 

Sample 

I.D. 

Gas Analyses Estimated 

H2O vapor 

v%(wet) 

Gas 

Density 

',amid 

CO2 

v% (dry) 

02 

v% (dry) 

NOx 

ppm (wet) 

11/29/93 13:51 - 15:32 390.7 9.5 235:2 194.7 272.4 382.4 1781.5 SGF-WB6 0.544 20.403 48.51 0.5 0.0739 

11/30/93 15:56 - 16:56 344.8 9.5 207.5 171.8 240.9 328.3 1571.9 SGF-VVB10 2.181 18.143 176.14 1.0 0.0742 

12/01/93 13:54 - 15:57 276.9 9.5 166.7 138.0 193.3 243.9 1262.6 SGF-VVB12 2.483 17.553 611.11 1.5 0.0741 

12/02/93 10:42 - 12:00 ND ND ND ND ND ND ND SGF-WB26 0.046 20.758 13.97 0.04 0.0738 

Fuel Estimate A: From the daily consumption on 12/01/93, 0.662 million BTU per long ton product 

Fuel Estimate B: From a long-term average of 0.548 million BTU per long ton product 
Table 6.4 Chemical Analyses of windbox dust and pellets for the Straight-Grate 

producing fluxed pellets. 

Sample 

Description 

Fet 

wt % 

Fe+2 

wt % 

Si 

wt % 

C 

wt % 

S 

wt % 

Oxidation' 

Pct. 

Calcine2 

Pct. 

Green Pellets 60.2 20.2 1.8 1.56 0.0160 0 0 

WB 10 60.8 15.7 1.8 1.46 0.0272 22.5 7.3 

WB 15 53.2 6.5 2.0 2.25 0.0685 63.4 Conc3 

WB 19 53.2 9.0 1.8 2.38 0.0482 49.3 Conc3 

WB 20 58.0 9.5 ND 1.39 0.137 50.9 7.52 

WB 21 60.6 10.6 1.8 1.03 0.181 47.5 34.4 

WB 23 61.0 9.7 1.8 0.96 0.165 52.3 39.3 

Fired Pellets 61.0 1.4 2.0 0.0115 0.0014 93.1 99.3 

1. Oxidation, % = (1 - ((3•Fe+21/Fet11"100 

2. Calcination, % : By means of C/Fe ratio. 

3. Carbon is concentrated in these samples. 
Table 6.5: Summary of results for the Straight-Grate producing fluxed pellets. 

Gas Sampling 

Location 

Gas 

Sample 

I.D. 

Est.A 

Fuel 

mcfh 

E st. B 

Fuel 

mcfh 

P1 

(actual) 

mcfh 

P2 

(actual) 

mcfh 

P3 

(actual) 

mcfh 

Gas Analyses Calculation with Fuel Est. A Calculation with Fuel Est. B _ 

CO2 

v% (dry) 

02 

v% (dry) 

NOx 

ppm (wet) 

Gas Flow 

mcfh 

NOx 

lb/hr 

NOx 

lb/MMBTU 

Gas Flow 

mcfh 

NOx 

lb/hr 

NOx 

lb/MMBTU 

Windbox 6 Hood SGF-WB6 235.2 194.7 0.0 0.0 178.1 0.544 20.403 48.510 3271 18.77 1.23 2739 15.71 1.24 

Windbox 10 Hood SGF-WB10 207.5 171.8 144.6 171.4 0.0 2.181 18.143 176.140 15406 320.91 2.12 14074 293.16 2.34 

Windbox 12 Hood SGF-W812 166.7 138.0 9.7 21.9 0.0 2.483 17.553 611.110 2836 204.96 4.55 2488 179.80 4.83 

Windbox 26 Hood SGF-WB26 ND ND ND ND ND 0.046 20.758 13.970 ND ND ND ND ND ND 

Fuel Estimate A: From the daily consumption on 12/01/93, 0.662 million BTU per long ton product 

Fuel Estimate B: From a long-term average of 0.548 million BTU per long ton product 

Fractional representation of fuel used in calculations: WB6, 6.5%; WB10, 73%; WB12, 27%. 
Table 6.6: Range of results for sample SGF-WB12 as the representation of fuel flow and pellet oxidation 

and pellet calcination is varied. 

Oxidation Fraction 0.3 0.4 0.5 0.3 0.4 0.5 0.3 0.4 0.5 0.09 0.12 0.15 

Calcination Fraction 0.4559 0.5090 0.5620 0.3966 0.4496 0.5027 0.3373 0.3903 0.4434 0.1190 0.1349 0.1508 

Fuel Fraction 1.25 1.25 1.25 1.00 1.00 1.00 0.75 0.75 0.75 0.30 0.30 0.30 

P1, mcfh 57.31 76.41 95.51 57.31 76.41 95.51 57.31 76.41 95.51 17.19 22.92 28.65 

P2, mcfh 110.36 123.22 136.05 96.01 108.84 121.69 81.65 94.48 107.34 28.81 32.66 36.51 

Fuel, mcfh 208.31 208.31 208.31 166.65 166.65 166.65 124.99 124.99 124.99 50.00 50.00 50.00, 

Calculated air flow, mcfh 13225 13758 14291 10900 11433 11966 8575 9108 9641 3270 3430 3590 

Calculated total flow, mcfh 13009 13534 14058 10722 11246 11771 8436 8959 9484 3217 3374 3531 

NOx flow, lb/hr 988 1026 1065 813 852 890 639 677 716 244 256 267 

Table 6.7: Range of results for sample SGF-WB10 as the representation of fuel flow and pellet oxidation 

and pellet calcination is varied. 

Oxidation Fraction 1.00 0.95 0.90 1.00 0.95 0.90 1.00 0.95 0.90 0.75 0.70 0.65 

Calcination Fraction 0.9820 0.9540 0.9260 0.8974 0.8695 0.8415 0.8129 0.7849 0.7570 0.5885 0.5606 0.5326 

Fuel Fraction 1.25 1.25 1.25 1.00 1.00 1.00 0.75 0.75 0.75 0.50 0.50 0.50 

P1, mcfh 238.07 226.17 214.26 238.07 226.17 214.26 238.07 226.17 214.26 178.55 166.65 154.75 

P2, mcfh 320.06 310.95 301.82 292.50 283.40 274.28 264.96 255.83 246.72 191.82 182.71 173.58 

Fuel, mcfh 259.37 259.37 259.37 207.50 207.50 207.50 155.62 155.62 155.62 103.75 103.75 103.75 

Calculated air flow, mcfh 25970 25562 25153 22410 22002 21593 18850 18441 18033 13247 12839 12430 

Calculated total flow, mcfh 25674 25271 24866 22155 21752 21347 18636 18231 17828 13096 12693 12288 

NOx flow, lb/hr 555 547 538 479 470 461 402 393 385 282 274 265 
FIGURES 
aqm apewril eq

uiniv 

°gold 6uijdwesseD 

Figure 1.1 

Pellet bed inside a laboratory furnace 

o 

o 

I 

( 

0 

N 

V 

o 4 

uop

atuii

sna pue seD 

04sep

ed eup.unly 

amprup equinly 
Figure 1.2 

Photolytic cycle for nitrogen oxides in the atmosphere 
1/4" NPT Stainless 

Steel Type 316 

KEY 

Figure 2.1 

Gas sampling probe 

Water In Water Out 

1 - Inner Tube 

2- Nut 

3- Back Ferrule 

4- Front Ferrule 

5 - End Body Of Water Jacket 

6- Outer Body Of Water Jacket 

7- Divider Tube Of Water Jacket 
1 

- --. -- ..- - 

14— 10 cm 

Figure 2.2 

Filter ancl.liner insert for the gas sampling probe 

1 2 5 

A. - Filter In Holder 

2 3 4 

r

om•■••• •••••••• 

B. - Filter Outside Of Holder 

KEY 

1 - Liner 

2 - Filter Holder 

3 - Tapered Sintered Bronze Filter 

4 - Neoprene 0-Ring 

5 - End Pipe 
Tempering 

air fan 

Stack 

Burner 

0 

Figure 3.1 

Process flow diagram for the Grate-Kiln producing acid pellets 

/1\ V 

Drying zone 

0 

Preheat 

Green pellets -\ 

Stack 

Kiln 

Waste gas 

fan 

1A & 1B 

preheat fans 

Annular cooler 

3A 

3BI 

• Cooling fans mir 

Fired 

pellets 

NI 
17.9 

17.8 

i 17,7 

ON 

17.8 

17.5 

1.52 

t 1.48 

It 1.44 

1.38 

300 

280 

260 

240 

220 

200 

80 

55 

50 

45 

40 

35 

12 

10 

8 

8 

4 

2 20 40 BO 80 100 

SAMPUNG TIME, min 

120 140 180 

Figure 3.2 

Gas analyses for the sample GKA-6a 10/18/93 
II 1.90 

O 1.88 

1.86 

1.84 

330 

V:, 320 

a 310 

O 

300 

290 

140 

f) .130 

Ea 120 

m 110 

16.6 

1.96 

1.94 

1.92 

15.4 

Figure 3.3 

Gas analysis for the sample GKA-5 10/19/93 

20 40 60 80 100 120 

SAMPLING TIME. min 
18.2 

•:;(*1 17.0 

16.8 

150 200 

1.2 

100 

SAMPLING TIME, min 

Figure 3.4 

Gas analysis for the sample GKA-3 10/20/93 
19.5 

18.5 

-1? 17.5 

lg. . 16.5 

oN 

15.5 

14.5 

1.4 

1.3 

1.0 

0.9 

260 

140 

60 

; 50 

E 

0 40 

30 

Figure 3.5 

Gas analysis for the sample GKA-6b 10/21/93 

150 200 250 300 

SAMPLING TIME, min 
1.1 

1.0 

0.8 

240 

V; 220 

3 

ix 200 

;( 0 

Z 180 

50 100 

SAMPLING TIME. min 

150 200 

CO, ppm (dry) 

Figure 3.6 

Gas analysis for the sample GKA-6c 10/22/93 
I 

515 - 

Figure 3.7 

Selected operating data for the GKA-3 sampling period 

I 1 I T T • 

Air\ \ 

- V \ 7' \ 1 '. I , / / I i 1.'--' \ 7 I I. \. ' 7 I 1 1 T ' 1 /77 I ' 

V 

N I i 1 \ k ■ \ : 

/ 

1 , ,li I i . I 7 1 1 1 i 

I V 1 

-...... -- 1 1 1 ■ 

200 

I , 

IVW 

114 1/ 

• 

11.\ 

7 \ 

A/ ,... 

\ \ 

. , 

7 i\ i i \\\\ 

\ 1 A 

1 / P 1 j 1 

i 

} 

1 '1 1\i 

\ 1 f 

I ..,... - 2198 -

1.i. 2196 

1 

1 1 

1 211\ I ---ir\; - 

so 

IS 2194 

2192 I , I / 

I 2190 1- 

2188 

1 ,../..„.. 

r 1 

1 2186 \\)/ 

u1) 2184 \ l'\\--\ 7 1 I 

2182 

0 50 100 Gas Sampling lime, min 150 200 
I 

.11010110 

490 i!! ! ! ! ! !, 1■ ! , ! ! Ni 

480 , I! 

470 !reed 

 ! 

460 

450 

.." I I 

\ !Fuel 

\ ! I L 

440 

430 

\ / .--- - , . 

U ' ! Gas Sampling 

. 420 I i 

air 

0 

a0 

1). 

0 

210 

200 

190 

. 180 

0 

T. 

0170 

12 160 

Z 150 

140 

130 

Figure 3.8 

Selected operating data for the GKA-5 sampling period 

450 -130 

E 

2.3 

120 0 

E 

400 

I 3B 

WG •c" 

co 

110 

a 

ca 

LL 

350 

IN/ _)/Nz 

3A 

300 -! 

C 

CO 

U- 

(6 

0 

0 

100 

Gas !Sampling 

660 720 780 840 900 960 

Time of Day, min 
U) f) 

4: 

120 

"E 

0 

ea 

110 en 

co 

u_ 

0 

U 

Figure 3.9 

Selected operating data for the GKA-6a sampling period 

220 

210 

200 

- 190 

180 

12.3 170 

160 

150 

140 

-. '-...111.4 

500 ii\i i i\ 

490 

480 

470 

/\ / \ \' I \ I Feed 1 

\ 1 I 1 INF kui i l rt li ., i wrii l\ , vam , NM I 

• If Y 

1 , I 

460 

450 

440 

> Fuel 

\ /I\ 

-7---- I . \/) 

1 

Gasl Sampling . 

, 430 • 1 

Green PelletFeed, long to

n/hr 

450 

U) 

a. 

E 

400 

03 u_ 

350 

CD 

a) 

300 -- 

660 720 

3B 

WG 

3A 

780 

Time of Day, min 

Gas Sampling 

840 900 
I 

490 

480 

- 

Figure 3.10 

Selected operating data for the GKA-6b sampling period 

A 1 I 1 ■ 1 1 I 

1 

° g 470 

/ 1 1 ' I •i ' I' I i ' -"-"''' . \ 1J 1, ' 1 ' 1 1 ;., t 

 R ivu V fl ,, .1, i , , 1 , , L , 1:1 0 o Li. 

7i 

'-g 46° 

1 i 7 I I I 

■ 

i ! \ ; \ ! I I 1\ i I A1t i \ 1, 7111 7 

a. 

c e 12 0 450 

I 

I \ j I n\ I / \/1 7 1 1 \It I / I 

I 1 1 '‘,...! 1i i i! t v 1 t • 1 

\i, 

440 - 

165 - 

160 

1 1 I 1 ! I 1 1 

I I I 

I I t

1 A i 

, , ' f , 

155 I 

! 

!7 i k / 

1 I i 

150 Tv--1. , 1 t , , 1 

: 

\y-, ■I \ h 1 t - \ ; 

0 145 1 , i , 

1 1 I 

MIIIIIIIIIIIMILIEWMINNIIIMMIL 

Ali 

i 

A 

I i 

71 

= 

1 iao I \i... 1 

I ! i I 1 i 

135 1 

I I 

y 

130 -r 

400 - 

! YYY 1 , 

I 

..\. 11 Nr 

/ 

i ' / \ 1 1- 

! n\ 

Jul I V i 

i t 

' 

1 ,.../ , 

........ , 

2166 - 1 

r\; 1 

1 

17 \.;\ 1 v 7\"-\jiV 1 , I 1 1 

1 1 I 

1 1 

1 1 1 

1 \ 2 

1 1 

1 1 1 \ I 

- .....- 

I 1 1 I 

0 50 100 150 200 250 300 350 Gas Sampling Time, min 
Figure 3.11 

Selected operating data for the GKA-6c sampling period 

1 1 

' 

. 1 ' % 7 A 7.\(\ 7.\ \L-...A\ ....,. ,- r 1 • 

\- \11

/%1 / \A / I; 

Net Feed, 

I! 1 \ ! 

v...--\. A 7' 

\ 7 \ r 

155 - 

150 

7 7 

1 i 

.. 145 I 11 I 1 

1 

g 140 

: 0 135 

! 

7-- l 

: n, \ IL 

-g 

. 

i 

N\\\. 

\ ! , 

125 I %, 

120 

1 1 

365 — 

350 

i in 1 r 

z 

E 355 i I c.) 

. . 

„. , 

1\.-- 

\ 

Iwo 

\Z i\I 

g / : 

-i , 1,/2\/"\ii.7 

345 -. 

2120 

SecondaryAlrTemperature.deg.F 

4 1 .. , ... ... ,, g K., r. g D O ■ I I . I 

1 

4.8 OW 

0 50 100 150 MO 

Gas Sampling Time, min 
Cu

bic Feetper Min

ute 

340 

345 350 355 360 365 370 375 380 385 390 

Motor Amps 

ACFM + SCFM 

395 

Figure 3.12 

Relationship between waste gas flow & fan current draw 
Figure 3.13 

Combustion curves for the Grate-Kiln producing acid pellets 
0 0 0 0 

Figure 3.14 

Relationship of NOx with CO2 for a Grate-Kiln producing acid pellets 

700 

600 

47 500 

Q 400 

>i" 

0 

z 300 

200 - 

100 -, 

0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 

CO2, pct (dry) 

0 

0 

c2) 

0 

100 0 

00 0 

O 9) 0 

0 (,' cs9 O. 0(§--• 0 

0 

+ GKA-6a A GKA-5 0 GKA-3 GKA-6b x GKA-6c 
Figure 3.15 

NOx mass flows for the Grate-Kiln producing acid pellets 

Li A 

AA 

Ei 

Li 

11 Cl 

A 

A 

--A 

700 

s_ 650 

0 600 

(l) 

CO 

cu 550 

0 

500 

450 

125 135 145 155 165 

Natural Gas Flow, mcfh 

o Process Flow Measured L Process Flow Calculated 
Figure 3.16 

Ratio of NOx flow to fuel input for a Grate-Kiln producing acid pellets 

H 

I-7 

A 

A 

AD 

ila 

A 

A D 

ILII - 

LI 

3.0 

125 

4.8 

4.6 

4.4 

m 4.2 

.2 4.0 

3.8 

3.6 

0 

Z 3.4 

3.2 

135 145 155 165 

Natural Gas Flow, mcfh 

Process Flow Measured IA Process Flow Calculated 
Hood exhaust fan 

Primary combustion 

From windbox chambers 

recup. fan Recup. 

fan 

bypass 

Figure 4.1 

Process flow diagram for the Straight-Grate producing acid pellets 

Windbox 

exhaust 

fan 

Green 

pellets 

V 

First cooling zone 

Burners 

MIC49111 

11111111111 

Updraft 

drying zone 

Down 

draft 

drying 

zone 

Preheat zone 1 

1 2 3 4 5 8 7 8 9 10 11 12 13 14 

Updraft Windbox Windbox No. drying exhaust Windbox 

recup 

15 16 17 18 19 20 21 2223 24 

Second 

cooling 

zone 

Fired 

pellets 

25 26 27 28 29 30 31 32 33 34 3538 37 38 

Cooling air duct 

Ambient air 

11— Dust 

collector Updraft 

drying 

fan 

Windbox recup. fan Cooling air fan 
20.3 Ma 

40 

a a 

x 

0 

ND • 4 

• 3 a 

O 

02 

1

0 10 20 30 40 50 

SAMPLING TIME. min 

0.34 

--- 0.30 

0. 0.26 

tV 

0 

C.)0.22 

0.18 

30 

11 

• 3 

7 a 

0 

49 5 

3 

5 

Figure 4.2 

Gas analysis for the sample SGA-WB16 04/20/94 

20.7 

20.6 

15 20.5 

o 20.4 
50 100 150 200 250 

SAMPUNG TIME, min 

Figure 4.3 

Gas analysis for the sample SGA-VVB18 04/21/94 

Low Primary Air 

16.4 

2.8 

'F 2.6 

as 2.4 

iv 

0 

0 2.2 

2.0 

800 

700 - 

Low Primary Air 

NOx, ppm (wet) 

5 

4 

3 

2 

10 

ND 
Figure 4.4 

Combustion curves for the Straight-Grate producing acid pellets 
Figure 4.5 

Relationship of NOx with CO2 for a Straight-Grate producing acid pellets 

800 

O 0 O 

El 750 

0 

-7. 700 4.

g. 650 

a. 

0 z 600 

550 - 

500 , 

2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 

CO2, pct (dry) 

o WB18 Normal • WB18 Low Primary Air 
Figure 4.6 

NOx mass flows for the Straight-Grate producing acid pellets 

350 

300 L._ _c 

250 

Cl) 

cn 

as 200 

O 

150 

100 , 

30 40 50 60 70 80 

Natural Gas Flow, mcfh 

A North Chamber Estimated ri South Chamber Regression 
Figure 4.7 

Ratio of NOx flow to heat input for a Straight-Grate producing acid pellets 

4.6 

4.4 

m 4.2 

0 

• 4.0 

1.23 

x-3.8 

0 

z 

3.6 

3.4 

20 

A 

AA 

f- (_\ 

\ 

I 

El 

171 FT 

n 

Li 71 

■ 

ri 

40 60 80 100 120 

Natural Gas Flow, mcfh 

Whole Furnace Estimated o South Combustion Chamber 
Tempering 

air fan 

Stack 

A 

-4( 

Burner 

0 

Figure 5.1 

Process flow diagram for the Grate-Kiln producing fluxed pellets 

Green pellets 

IN V 

Burner—•0 

Drying zone 

Stack 

• 

Burners 

sci\b 

Preheat 

2 burners 

• 

Kiln 

Annular cooler 

Waste gas 

fan 

1 A & 1B 

preheat fans 

Fired 

pellet; 

3A 3B 

• Cooling fans • 
Figure 5.2 

Gas analysis for the sample GKF-1 10/07/93 

Figure 5.4 

Gas analysis for the sample GKF-4 10/05/93 
Figure 5.5 

Gas analysis for the sample GKF-5 10/04/93 
19.0 

1&8 

Figure 5.6 

Gas analysis for the sample GKF-6a 09/28/93 
fr 

28 

a24 C. 

O 020 

160 50 100 150 

SAMPLING TIME, min 

32 

Figure 5.7 

Gas analysis for the sample GKF-6b 09/30/93 

17.1 

16.9 

1 

ON 16.7 

16.5 

3.3 

3.2 

o at 

270 

I 260 

o. 

- 250 

Ox 

240 

230 

50 

40 

a 30 C. 

CV 

10 

200 250 
160 — 

t 140 — 

E 

-q 120 — LL 

I! 100 — 

Z - 

80 — 

60 - 

Grate 

r 

L 

r r 

450 

448 

E 

0 

0, 446- 

0 

ti 

c 

444 tL 

113 

CL 442 - c 

co 

440 — 

438 

125 380 

370 E

0- 

ee 

360 a 

z 

350 8 

U340 is 

330 g 

 320 

50 100 150 200 250 

Gas Sampling Time, min 

95 

0 

Figure 5.8 

Selected operating data during the GKF-3 sampling period 
,Figure 5.9 

Combustion curves for the Grate-Kiln producing fluxed pellets 

2 3 4 5 6 

CO2, Volume Percent (dry) 
0 2 3 4 5 6 

CO2, pct (dry) 

Figure 5.10 

Relationship of NOx with CO2 for a Grate-Kiln producing fluxed pellets 

1 000 

800 

600 - 

E 

400 

0 

200 

0 

o GKF-3 + GKF-4 ❑ GKF-5 v GKF-6b x GKF-6a 

r 

L 

r 

L 

r 

r 

*NW 

- 

J 

L . 
750 

700 

X650 

.ift 

600 

0 

0550 

co (13 

E 500 

o z 450 

400 

Figure 5.11 

NOx mass flows for the Grate-Kiln producing fluxed pellets 

LX\ 

A 

A r I A 

I 

A 

.1 -

Ll 

Li 

Li 

A 

350 

140 160 180 200 220 240 

Natural Gas Flow, mcfh 

A Process Flow Measured Process Flow Calculated 
Figure 5.12 

Ratio of NOx flow to fuel input for a Grate-Kiln producing fluxed pellets 

3.3 

LX\ 

3.1 

00 

c • 0 2 9 

n 2.7 

0 

2.5 

A 

A 

2.3 - 

140 160 180 200 

Natural Gas Flow, mcfh 

220 240 

A Process Flow Measured IA Process Flow Calculated 
Windbox recup. fan 

Ambient air 

.4.--- 

Cooling air fan 

Updraft Windbox Windbox 

drying exhaust recup 

0 

Cooling air duct 

Dust 

1 

collector Updraft 

drying 

fan 

Windbox No. 

Figure 6.1 

Process flow diagram for the Straight-Grate producing fluxed pellets 

Hood exhaust fan 

Windbox 

exhaust 

fan 

Recup. 

bypass 

fan 

Primary combustion 

From windbox chambers n4--Burners recup. fan ••• 

Green 

pellets 

Updraft 

drying zone 

Down 

draft 

drying 

zone 

• • 

eN. es% 4/**, 0.0"••• 

/ I 

:::-.7". = r 

... 

..)

v

::.) ..., r-i 1 ...... .....- 1 . Preheat zone..2::2_ "--J 

(eight burners) 

.•■•■• 1111.• 

• • 

First cooling zone = Second 

cooling 

zone 

Fired 

pellets 

1 2 3 4 5 6 7 8 9 10 1112 1314 1516 17 18 1920 21 22 23 24 2526 2728 29 30 31 32 33 34 35 36 37 38 

V 
Figure 6.2 

Gas analysis for the sample SGF-WB6 11/29/93 
Figure 6.3 

Gas analysis for the sample SGF-WB10 11/30/93 
Figure 6.4 

Gas analysis for the sample SGF-WI312 12/01/93 
Figure 6.5 

Gas analysis for the sample SGF-WB26 12/02/93 
L 

- 

i I I 

I I ; I 

I I I I I t 

I 

Figure 6.6 

Burn-through temperature and NOx for a Straight-Grate producing fluxed pellets. 

1100 

^ 1000 

E

415 

§. 900 

0. 

><- 800 0 

z 

700 

L 

2): 600 

T. a) 500 

E 

Fa2 400 

300 

600 660 720 780 840 900 960 1020 1080 1140 1200 

Time of day, min 
Key 

* WB6 

0 WB10 

0 WB12 

A WB26 

Theoretical 

Figum 6.7 

Combustion curves for the Straight-Grate producing flux pellets 

21 

0-... , 20 

G.- .0 

C 

04)19 

a) 

a. 

a) 

18 

= 

a 

0 17 

16 

0 0.5 1 1.5 2 2.5 3 3.5 

CO2, Volume Percent (dry) 
Figure 6.8 

Relationship of NOx with CO2 for a Straight-Grate producing fluxed pellets. 

1000 - 

800 

.1.7 

3) 600 

E 

a 

a 

)i 400 

0 

z 

200 

1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 

CO2, pct (dry) 

_, 

1 

Is 

WB12 

ED 

WB10 
Figure 7.1 

NOx mass flows measured for iron ore pelletizing furnaces 

• • 

• • 

• • 

• • 

4 - , -4 

1 

A 

350 -, 

100 

750 

700 

2E 650 

:c3 *.

- 600 

O 

co550 

co 

E 500 

° 450 

400 

II I 4, 

4 A L 

r 

r IIA - 

• 

• I I 

I I 

1 

• r t 

I I 

AP, 

- 

- 

120 140 160 180 200 220 240 

Natural Gas Flow, mcfh 

o GKA ❑ GKF v SGA 

Solid points indicate values derived from process gas flow measurements 
Figure 7.2 

Ratio of NOx flow to heat input for iron ore pelletizing furnaces 

5.0 

4.5 

m 4.0 

0 

•

_ 3.5 

113 

0 

• 

3.0 

z 

2.5 

2.0 , 

100 

I I 

I I 

I I 

- I- 4, 

I I 

I I 

1 1 

I I 

I I 

L, 

A I I 

U 

r 1111 

120 140 160 180 200 220 240 

Natural Gas Flow, mcfh 

A 

A 

✓

r 

A GKA a GKF v SGA 

Solid points indicate values derived from process gas flow measurements 
APPENDIX A 
Grate-Kiln 

10/18/93 

Hr : Mn 

Port 6a 

CO2 

Time % (dry) 

Acid 

CO SO2 NOx 

ppm (dry) ppm (wet) ppm (wet) 

02 

% (dry) 

11 : 27 0 1.49 7.81 44.3 270.6 17.10 

11 : 30 3 1.49 7.01 48.7 241.5 16.22 

11 : 33 6 1.49 6.57 48.8 228.4 15.85 

11 : 39 12 1.49 5.14 17.82 

11 : 42 15 1.49 4.93 47.2 281.7 17.71 

11 : 45 18 1.50 5.33 46.4 276.0 17.72 

11 : 48 21 1.47 4.71 48.0 259.8 17.68 

11 : 51 24 1.41 3.91 51.5 266.1 17.74 

11 : 54 27 1.46 3.64 50.0 262.4 17.63 

11 : 57 30 1.45 3.57 48.5 240.4 17.62 

12 : 0 33 1.44 9.92 39.3 222.5 17.66 

12 : 3 36 1.42 9.56 49.2 217.3 17.63 

12 : 6 39 1.44 8.55 50.3 246.6 17.62 

12 : 9 42 1.39 7.58 45.3 215.1 17.69 

12 : 12 45 1.38 7.03 48.1 206.5 17.72 

12 : 15 48 1.43 6.86 48.3 245.8 17.64 

12 : 18 51 1.45 9.79 45.5 235.1 17.64 

12 : 21 54 1.42 8.88 50.3 220.9 17.64 

12 : 24 57 1.43 8.43 55.6 222.4 17.65 

12: 27 60 1.44 8.86 52.1 218.9 17.60 

12 : 30 63 1.48 10.59 17.80 

12 : 33 66 1.47 9.79 56.6 248.9 17.62 

12: 36 69 1.48 9.62 59.2 258.4 17.62 

12: 39 72 1.49 9.86 57.3 269.5 17.60 

12 : 42 75 1.48 9.88 54.1 276.6 17.66 

12 : 45 78 1.45 9.56 55.7 232.4 17.67 

12 : 48 81 1.42 9.11 59.0 228.6 17.67 

12 : 51 84 1.41 9.11 38.4 202.4 17.82 

12: 54 87 1.42 8.81 48.5 220.7 17.76 

12 : 57 90 1.41 8.54 53.7 221.9 17.73 

13 : 0 93 1.41 8.58 56.0 218.0 17.72 

13 : 3 96 1.44 8.37 55.8 252.6 17.68 

13 : 6 99 1.40 8.03 55.1 224.3 17.78 

13 : 9 102 1.38 8.02 58.2 212.4 17.77 

13: 12 105 1.40 7.63 59.2 223.0 17.73 

13 : 15 108 1.38 7.60 56.8 203.8 17.73 

13 : 18 111 1.39 7.05 58.8 225.8 17.72 

13 : 21 114 1.41 10.68 17.82 

13 : 24 117 1.42 10.86 48.6 214.6 17.70 

13 : 27 120 1.44 10.89 51.4 222.6 17.65 

13 : 30 123 1.44 10.96 53.8 219.8 17.64 

13 : 33 126 1.44 10.76 57.7 243.2 17.61 

13 : 36 129 1.44 10.51 55.6 229.1 17.66 

13 : 39 132 1.42 10.41 54.5 216.3 17.67 

13 : 45 138 1.44 11.33 40.9 248.7 17.57 

13 : 48 141 1.42 11.17 56.8 212.6 17.61 

13 : 51 144 1.42 10.91 55.1 227.4 17.60 

13 : 54 147 1.44 10.99 55.6 256.2 17.54 

13 : 57 150 1.43 10.91 56.7 224.0 17.56 

14 : 0 153 1.41 10.65 56.4 218.2 17.57 

Boxed values are identified as outliers 
Grate-Kiln 

10/19/93 

Hr : Mn 

Port 5B Acid 

NO NOx SO2 

Time ppm (wet) ppm (wet) ppm (wet) ppm 

CO 

(dry) 

02 

% (dry) 

CO2 

% (dry) 

13 : 29 0 300 320 130 10.0 16.60 1.90 

13 : 34 5 300 300 130 9.0 16.40 1.90 

13 : 40 11 310 310 130 8.5 15.90 1.90 

13 : 46 17 330 300 120 8.5 15.80 1.90 

13 : 50 21 310 295 120 8.0 15.80 1.90 

13 : 55 26 310 305 120 7.5 15.60 1.90 

14 : 0 31 310 305 130 7.0 15.50 1.90 

14 : 5 36 300 300 120 6.5 15.60 1.90 

14 : 10 41 300 315 120 6.5 15.50 1.90 

14 : 15 46 330 330 120 6.0 15.40 1.95 

14 : 20 51 310 310 130 10.5 16.20 1.90 

14 : 27 58 2901 290 120 10.5 16.00 1.90 

14 : 35 66 310 315 120 9.5 15.70 1.90 

14 : 40 71 310 310 120 10.0 15.70 1.85 

14 : 50 81 330 310 110 9.0 15.70 1.85 

14 : 55 86 320 310 120 8.5 15.70 1.85 

15 : 0 91 320 310 110 8.5 15.70 1.85 

15 : 6 97 320 320 110 11.0 16.10 1.90 

15 : 10 101 320 320 120 10.0 16.00 1.90 

15 : 15 106 320 320 120 10.0 16.00 1.90 

Boxed values are identified as outliers 
Grate-Kiln 

10/20/93 

Hr : Mn Time 

Port 3 

CO2 

% (dry) 

Acid 

CO SO2 

ppm (dry) ppm (wet) ppm 

NOx 

(wet) 

Page 1 of 2 

02 

% (dry) 

10 : 24 0 1.66 0.00 21.8 574.7 17.17 

10 : 27 3 1.66 0.00 34.3 527.4 17.16 

10 : 30 6 1.89 0.00 37.5 608.0 16.79 

10: 33 9 1.74 0.00 35.4 604.7 16.78 

10 : 36 12 1.55 0.00 27.4 582.1 16.88 

10 : 39 15 1.55 0.00 36.6 561.6 16.79 

10 : 42 18 1.46 0.00 33.9 516.7 16.83 

10 : 45 21 1.56 1.15 30.9 536.3 17.56 

10 : 48 24 1.64 0.93 32.3 563.2 17.50 

10 : 51 27 1.40 0.57 33.4 556.0 17.97 

10 : 54 30 1.69 0.28 41.5 543.3 17.14 

10 : 57 33 1.49 0.00 35.6 524.2 17.56 

11 : 0 36 1.35 0.00 34.5 529.5 17.58 

11 : 3 39 1.41 0.00 30.2 487.2 17.49 

11 : 6 42 1.27 0.00 29.4 514.6 17.94 

11 : 9 45 1.48 0.92 24.8 537.9 17.64 

11 : 12 48 1.61 0.37 28.8 506.4 17.49 

11 : 15 51 1.52 0.30 30.6 569.6 17.49 

11 : 18 54 1.65 0.03 30.2 544.6 16.83 

11 : 21 57 1.16 0.00 31.5 461.5 17.84 

11 : 24 60 1.38 0.00 28.8 459.5 17.36 

11 : 27 63 1.51 0.00 30.1 545.4 17.20 

11 : 30 66 1.46 0.00 22.7 558.3 17.45 

11 : 33 69 1.57 0.00 30.5 494.2 17.09 

11 : 36 72 1.35 0.00 34.9 467.9 17.32 

11 : 39 75 1.56 0.00 36.2 575.2 17.17 

11 : 42 78 1.52 0.64 27.0 500.9 17.07 

11 : 45 81 1.61 0.46 37.3 560.4 17.40 

11 : 48 84 1.53 0.27 33.0 612.2 17.63 

11 : 51 87 1.59 0.04 44.5 550.4 17.37 

11 : 54 90 1.66 0.08 31.7 587.5 17.53 

11 : 57 93 1.76 0.14 29.3 677.7 17.04 

Boxed values are identified as outliers 
Grate-Kiln 

10/20/93 

Hr : Mn Time 

Port 3 

CO2 

% (dry) 

Acid 

CO SO2 NOx 

ppm (dry) ppm (wet) ppm (wet) 

Page 2 of 2 

02 

% (dry) 

12 : 0 96 1.60 0.00 29.7 594.4 17.31 

12 : 3 99 1.74 0.00 31.7 610.2 16.61 

12 : 6 102 1.36 0.00 27.8 553.3 17.60 

12 : 9 105 1.36 0.00 30.5 513.3 17.47 

12 : 12 108 1.44 0.00 32.3 540.2 17.49 

12 : 15 111 1.55 0.00 38.7 492.7 17.17 

12 : 18 114 1.50 0.00 36.9 530.5 17.31 

12 : 21 117 1.26 0.00 44.2 491.8 17.73 

12 : 24 120 1.39 0.03 15.0 497.7 17.63 

12 : 27 123 1.43 0.79 33.7 538.1 17.92 

12 : 30 126 1.53 0.45 32.1 489.2 17.75 

12 : 33 129 1.56 0.44 35.8 570.6 17.42 

12 : 36 132 1.32 0.40 31.7 516.3 18.06 

12 : 39 135 1.40 0.42 37.3 497.0 17.73 

12 : 42 138 1.33 0.31 33.0 497.7 17.88 

12 : 45 141 1.17 0.36 28.9 489.5 18.09 

12 : 48 144 1.31 0.40 26.0 486.4 17.64 

12 : 51 147 1.41 0.51 27.6 514.1 17.90 

12 : 54 150 1.51 0.78 33.6 508.9 17.56 

12 : 57 153 1.34 0.63 34.4 482.6 17.80 

13 : 0 156 1.53 0.77 29.8 416.0 17.35 

13 : 3 159 1.36 0.92 38.0 479.4 17.79 

13 : 6 162 1.36 0.96 29.7 482.1 17.67 

13 : 9 165 1.40 0.93 30.1 481.0 17.70 

13 : 12 168 1.17 0.86 33.6 455.8 18.01 

13 : 15 171 1.33 0.721 48.8 464.1 17.62 

13 : 18 174 1.53 0.82 40.8 416.01 17.35 

13 : 21 177 1.42 0.85 36.3 478.9 17.65 

13 : 24 180 1.43 0.68 33.2 514.5 17.30 

13 : 27 183 1.39 0.61 37.0 17.64 

Boxed values are identified as outliers 
Page 1 of 2 

02 02 

(dry) Corrected 

20.77 21.61 

17.88 18.73 

17.80 18.67 

19.94 20.82 

16.93 17.83 

16.42 17.33 

16.17 17.10 

16.05 16.98 

16.04 16.99 

16.03 16.99 

16.03 17.01 

16.10 17.09 

15.98 16.99 

15.99 17.01 

15.99 17.02 

15.79 16.84 

15.88 16.94 

15.86 16.94 

15.96 17.05 

15.97 17.08 

16.00 17.12 

16.05 17.19 

16.08 17.23 

16.11 17.27 

15.68 16.86 

15.74 16.93 

15.81 17.02 

15.86 17.08 

15.93 17.16 

15.93 17.17 

15.95 17.22 

16.01 17.29 

16.03 17.31 

16.02 17.32 

16.80 18.12 

15.64 16.97 

15.74 17.08 

15.73 17.09 

15.80 17.17 

15.89 17.28 

15.91 17.31 

15.97 17.39 

15.97 17.40 

15.94 17.38 

15.90 17.36 

15.89 17.36 

15.94 17.43 

15.93 17.43 

15.96 17.47 

15.51 17.04 

15.62 17.16 

NOx 

ppm (wet) 

4.81 

258.1 

240.6 

149.3 

209.0 

245.8 

218.3 

207.1 

218.8 

220.9 

236.9 

211.3 

240.2 

213.2 

215.3 

226.1 

225.1 

221.6 

222.9 

207.8 

208.9 

207.5 

196.8 

198.8 

242.5 

229.5 

221.3 

218.2 

203.5 

217.1 

202.7 

195.4 

182.0 

187.0 

I 

6.0 

213.5 

218.5 

233.5 

211.7 

220.3 

201.8 

187.8 

170.7 

200.5 

223.1 

195.7 

188.8 

178.4 

168.7 

203.4 

195.0 

Grate-Kiln 

10/21/93 

Hr : Mn Time 

Port 6b 

CO2 

% (dry) 

Acid 

CO 

ppm (dry) 

SO2 

ppm (wet) 

11 : 28 0 0.00 0.61 

11 : 31 3 1.30 7.66 33.3 

11 : 34 6 1.27 7.11 38.7 

11 : 37 9 0.00 39.4 

11 : 40 12 1.20 6.76 52.4 

11 : 43 15 1.28 6.60 51.3 

11 : 46 18 1.25 5.85 48.1 

11 : 49 21 1.21 5.56 47.7 

11 : 52 24 1.22 5.57 45.4 

11 : 55 27 1.21 5.53 44.7 

11 : 58 30 1.19 4.86 48.4 

12 : 1 33 1.14 4.31 46.5 

12 : 4 36 1.19 4.24 45.4 

12 : 7 39 1.16 4.39 46.0 

12 : 10 42 1.16 3.89 47.3 

12 : 13 45 1.25 4.31 47.4 

12 : 16 48 1.20 3.65 51.5 

12 : 19 51 1.21 3.63 50.3 

12 : 22 54 1.16 2.88 50.7 

12 : 25 57 1.15 2.71 47.9 

12 : 28 60 1.13 1.85 48.3 

12 : 31 63 1.11 1.38 47.0 

12 : 34 66 1.09 1.30 44.8 

12 : 37 69 1.07 1.24 44.0 

12 : 40 72 1.24 11.38 45.9 

12 : 43 75 1.22 10.66 49.2 

12 : 46 78 1.17 10.38 49.7 

12 : 49 81 1.13 9.86 48.2 

12 : 52 84 1.09 9.47 47.2 

12 : 55 87 1.11 9.40 46.4 

12 : 58 90 1.08 9.16 44.4 

13 : 1 93 1.03 8.44 43.7 

13 : 4 96 1.01 8.47 43.1 

13 : 7 99 1.02 8.55 42.2 

13 : 10 102 1.15 10.86 4.71 

13 : 13 105 1.21 11.36 46.5 

13 : 16 108 1.15 10.86 48.7 

13 : 19 111 1.17 10.39 51.7 

13 : 22 114 1.12 10.12 48.6 

13 : 25 117 1.08 10.08 48.6 

13 : 28 120 1.06 9.51 47.0 

13 : 31 123 1.02 9.04 44.6 

13 : 34 126 1.02 8.74 42.9 

13 : 37 129 1.04 8.59 43.6 

13 : 40 132 1.05 11.66 44.2 

13 : 43 135 1.04 11.59 44.8 

13 : 46 138 1.00 9.86 46.9 

13 : 49 141 0.97 10.12 44.4 

13 : 52 144 0.95 9.60 42.0 

13 : 55 147 1.12 11.45 40.7 

13 : 58 150 1.08 10.64 47.5 

Boxed values are identified as outliers 
Grate-Kiln 

10/21/93 

Hr : Mn 

Port 6b 

CO2 

Time % (dry) 

Acid 

CO SO2 NOx 

ppm (dry) ppm (wet) ppm (wet) 

02 

% (dry) 

Page 2 of 2 

02 

Corrected 

14 : 1 153 1.07 9.95 44.3 196.8 15.65 17.20 

14 : 4 156 1.10 9.72 44.8 213.0 15.65 17.22 

14 : 7 159 1.07 9.80 44.7 196.4 15.69 17.27 

14 : 10 162 1.09 10.10 44.5 219.7 15.66 17.26 

14 : 13 165 1.08 9.05 45.3 197.3 15.69 17.30 

14 : 16 168 0.99 8.62 45.4 183.7 15.79 17.42 

14 : 19 171 0.96 8.44 42.2 182.0 15.85 17.49 

14 : 22 174 0.97 8.08 43.2 185.1 15.82 17.47 

14 : 25 177 1.03 7.86 44.5 191.0 15.75 17.41 

14 : 28 180 0.99 7.33 45.2 185.5 15.80 17.49 

14 : 31 183 0.99 7.18 42.3 182.8 15.79 17.49 

14 : 34 186 0.97 6.53 42.8 191.1 15.80 17.51 

14 : 37 189 1.15 10.88 41.3 209.6 15.43 17.15 

14 : 40 192 1.15 12.38 51.9 215.0 15.46 17.20 

14 : 43 195 1.08 11.36 48.9 198.1 15.55 17.31 

14 : 46 198 1.07 11.67 46.8 200.9 15.60 17.37 

14 : 49 201 1.03 11.07 45.6 195.0 15.61 17.40 

14 : 52 204 1.05 9.98 47.0 201.7 15.58 17.37 

14 : 55 207 1.05 10.18 47.2 198.0 15.55 17.36 

14 : 58 210 1.05 9.82 47.2 195.0 15.56 17.38 

15 : 1 213 1.04 9.17 45.8 201.1 15.56 17.40 

15 : 4 216 1.00 8.89 46.6 188.3 15.61 17.46 

15 : 7 219 0.98 8.36 44.3 187.6 15.66 17.52 

15 : 10 222 0.95 7.62 42.2 178.9 15.71 17.58 

15 : 13 225 1.11 11.40 43.4 209.3 15.30 17.19 

15 : 16 228 1.10 11.06 49.4 213.3 15.38 17.29 

15 : 19 231 1.11 11.00 52.1 228.7 15.40 17.32 

15 : 22 234 1.07 10.54 49.7 201.1 15.47 17.40 

15 : 25 237 1.06 9.79 49.0 212.0 15.51 17.46 

15 : 28 240 1.03 9.79 49.1 206.6 15.56 17.52 

15 : 31 243 1.02 9.50 47.6 198.2 15.59 17.56 

15 : 34 246 1.05 9.18 48.5 213.1 15.53 17.53 

15 : 37 249 1.00 8.44 47.1 188.8 15.60 17.61 

15 : 40 252 0.98 7.54 43.6 181.5 15.61 17.63 

15 : 43 255 1.11 9.01 46.1 207.1 15.28 17.32 

15 : 46 258 1.08 5.47 48.5 200.8 15.41 17.46 

15 : 49 261 1.04 7.30 47.4 187.2 15.44 17.50 

15 : 52 264 1.06 14.48 45.6 192.0 15.45 17.52 

15 : 55 267 1.04 13.84 44.0 191.1 15.46 17.55 

15 : 58 270 1.00 12.67 45.0 191.7 15.50 17.60 

16 : 1 273 0.97 13.03 45.0 181.5 15.52 17.64 

16 : 4 276 1.00 13.14 45.0 178.4 15.48 17.62 

16 : 7 279 1.12 9.74 28.7 175.0 15.00 17.15 

16 : 10 282 1.07 9.32 51.7 201.6 15.25 17.41 

16 : 13 285 1.09 9.07 49.8 194.3 15.30 17.47 

16 : 16 288 1.06 8.31 46.7 192.7 15.30 17.49 

16 : 19 291 1.02 6.94 45.7 189.9 15.36 17.56 

16 : 22 294 1.01 10.08 43.4 185.6 15.39 17.61 

16 : 25 297 0.99 10.04 43.5 183.5 15.40 17.63 

16 : 28 300 1.00 10.04 44.5 195.1 15.39 17.63 

16 : 31 303 0.97 9.59 43.1 173.9 15.44 17.70 

Boxed values are identified as outliers 
Grate-Kiln 

10/22/93 

Hr : Mn 

Port 6c 

CO2 

Time % (dry) 

Acid 

CO SO2 NOx 

ppm (dry) ppm (wet) ppm (wet) 

Page 1 of 2 

02 

% (dry) 

10 : 16 0 1.06 5.12 43.1 216.9 19.46 

10 : 19 3 1.04 5.40 43.2 207.6 19.14 

10 : 22 6 1.00 4.70 43.3 207.9 19.01 

10 : 25 9 0.98 4.35 41.9 194.9 18.97 

10 : 28 12 0.99 4.49 41.6 199.4 18.92 

10 : 31 15 0.98 4.27 41.8 209.5 18.90 

10 : 34 18 0.99 4.04 42.3 206.4 18.87 

10 : 37 21 1.02 4.05 41.7 204.4 18.85 

10 : 40 24 0.99 4.02 43.0 202.1 18.86 

10 : 43 27 1.01 3.92 43.8 200.9 18.84 

10 : 46 30 1.07 4.17 45.4 228.7 18.49 

10 : 49 33 1.04 4.08 47.2 213.5 18.61 

10 : 52 36 1.01 3.78 46.4 207.7 18.65 

10: 55 39 0.98 3.79 44.8 200.0 18.74 

10: 58 42 0.98 3.92 45.8 213.8 18.74 

11 : 1 45 0.96 3.56 43.7 194.1 18.78 

11 : 4 48 0.96 3.74 41.6 193.1 18.76 

11 : 7 51 0.99 3.66 44.1 208.9 18.75 

11 : 10 54 0.99 3.15 44.4 200.1 18.72 

11 : 13 57 0.94 2.99 41.7 183.1 18.81 

11 : 16 60 1.03 3.76 34.1 207.6 18.65 

11 : 19 63 0.97 3.20 43.3 192.7 18.73 

11 : 22 66 0.99 3.25 43.8 204.5 18.51 

11 : 25 69 0.96 2.93 44.0 190.0 18.58 

11 : 28 72 0.94 2.69 44.6 186.9 18.62 

11 : 31 75 0.99 2.38 45.4 216.1 18.55 

11 : 34 78 1.05 2.57 48.0 222.3 18.43 

11 : 37 81 1.06 2.69 48.3 222.6 18.42 

11 : 40 84 0.97 2.26 48.5 195.9 18.55 

11 : 43 87 0.94 1.76 44.6 183.3 18.60 

11 : 46 90 1.02 3.02 35.4 210.5 18.48 

11 : 49 93 0.97 2.05 44.1 201.5 18.55 

11 : 52 96 0.95 2.43 42.4 193.7 18.58 

11 : 55 99 0.92 2.03 39.9 175.8 18.61 

11 : 58 102 0.92 1.81 41.3 184.8 18.63 

Boxed values are identified as outliers 
Grate-Kiln 

10/22/93 

Hr : Mn 

Port 6c Acid 

CO2 CO SO2 NOx 

Time % (dry) ppm (dry) ppm (wet) ppm (wet) 

Page 2 of 2 

02 

% (dry) 

12 : 1 105 0.90 1.33 42.5 191.8 18.63 

12 : 4 108 0.94 1.32 42.1 190.5 18.55 

12 : 7 111 0.95 1.04 42.9 200.6 18.54 

12 : 10 114 0.95 1.13 40.9 187.4 18.52 

12 : 13 117 0.94 0.83 41.1 181.7 18.51 

12 : 16 120 0.95 0.78 43.5 194.1 18.47 

12 : 19 123 0.94 0.44 41.2 195.0 18.50 

12 : 22 126 0.92 0.37 42.3 196.1 18.50 

12 : 25 129 0.99 7.221 21.81 156.31 18.03 

12 : 28 132 0.95 6.11 47.5 196.4 18.38 

12 : 31 135 0.96 5.34 47.3 199.9 18.35 

12 : 34 138 0.95 4.92 45.7 208.1 18.37 

12 : 37 141 0.96 18.22 46.3 207.2 18.35 

12 : 40 144 0.94 17.62 47.8 192.7 18.35 

12 : 43 147 0.92 17.50 44.8 189.1 18.40 

12 : 46 150 0.90 17.28 43.5 188.4 18.39 

12 : 49 153 0.93 17.58 42.5 188.7 18.33 

12 : 52 156 0.93 17.47 43.0 200.0 18.27 

12 : 55 159 0.89 16.97 42.3 184.5 18.29 

12 : 58 162 0.89 16.68 41.7 176.8 18.28 

13 : 1 165 0.92 16.91 42.3 192.3 18.19 

13 : 4 168 0.92 16.74 43.0 186.4 18.12 

13 : 7 171 0.98 16.85 28.1 180.4 18.45 

13 : 10 174 0.93 16.27 44.7 188.3 18.47 

13 : 13 177 0.94 15.77 47.3 196.6 18.43 

13 : 16 180 1.02 16.05 47.3 217.0 18.29 

Boxed values are identified as outliers 
APPENDIX B 
Straight-Grate 

04/20/94 

H : M : S 

Wind Box 16 

SO2 

Time, min ppm (wet) ppm 

Acid Pellets 

CO NOx 02 

(dry) ppm (wet) pct (dry) 

Page 1 of 1 

CO2 

pct (dry) 

12 : 7 : 22 -0.0 7.92 0.07 49.55 20.40 0.304 

12 : 8 : 22 1.0 9.00 0.42 48.36 20.40 0.314 

12 : 9 : 22 2.0 

12 : 10 : 22 3.0 7.38 0.59 40.45 20.46 0.277 

12 : 11 : 22 4.0 

12 : .12 : 22 5.0 5.66 0.49 45.73 20.34 0.295 

12 : 13 : 22 6.0 8.96 1.02 51.09 20.32 0.332 

12 : 14 : 22 7.0 8.51 0.76 47.35 20.42 0.310 

12 : 15 : 22 8.0 9.43 0.85 49.95 20.36 0.323 

12 : 16 : 22 9.0 8.72 0.74 45.88 20.38 0.319 

12 : 17 : 22 10.0 8.23 0.33 44.65 20.42 0.288 

12 : 18 : 22 11.0 8.84 0.12 46.65 20.37 0.307 

12 : 19 : 22 12.0 9.69 0.47 49.26 20.34 0.324 

12 : 20 : 22 13.0 9.30 0.52 44.49 20.39 0.306 

12 : 21 : 22 14.0 9.05 0.78 44.53 20.38 0.306 

12 : 22 : 22 15.0 9.30 1.26 48.23 20.39 0.318 

12 : 29 : 22 22.0 8.54 1.18 57.59 20.38 0.306 

12 : 30 : 22 23.0 8.92 0.49 51.69 20.39 0.297 

12 : 31 : 22 24.0 8.83 0.88 44.13 20.48 0.268 

12 : 32 : 22 25.0 7.74 0.38 36.90 20.50 0.235 

12 : 33 : 22 26.0 7.79 0.87 37.61 20.50 0.245 

12 : 34 : 22 27.0 6.77 1.09 37.53 20.51 0.259 

12 : 35 : 22 28.0 7.50 0.54 37.66 20.49 0.248 

12 : 36 : 22 29.0 7.64 0.39 37.39 20.51 0.252 

12 : 37 : 22 30.0 7.40 0.57 35.05 20.54 0.239 

12 : 38 : 22 31.0 7.57 35.42 20.54 0.222 

12 : 39 : 22 32.0 7.07 0.34 32.71 20.54 0.219 

12 : 40 : 22 33.0 7.92 0.75 35.73 20.51 0.244 

12 : 41 : 22 34.0 6.42 1.09 35.75 20.56 0.236 

12 : 42 : 22 35.0 6.22 0.68 30.68 20.58 0.207 

12 : 43 : 22 36.0 6.23 0.42 33.44 20.62 0.194 

12 : 44 : 22 37.0 6.22 0.60 37.28 20.53 0.226 

12 : 45 : 22 38.0 8.75 0.94 45.21 20.46 0.277 

12 : 46 : 22 39.0 7.77 0.44 40.81 20.53 0.242 

12 : 47 : 22 40.0 7.66 0.66 39.13 20.53 0.242 

12 : 48 : 22 41.0 6.54 0.99 34.10 20.59 0.206 

12 : 49 : 22 42.0 7.38 1.41 39.99 20.57 0.235 

12 : 50 : 22 43.0 8.22 1.03 48.43 20.47 0.258 

12 : 51 : 22 44.0 8.63 1.38 48.23 20.47 0.273 

12 : 52 : 22 45.0 7.33 0.89 41.02 20.55 0.235 

12 : 53 : 22 46.0 7.80 1.24 45.87 20.55 0.249 

12 : 54 : 22 47.0 9.10 1.46 55.92 20.38 0.301 

12 : 55 : 22 48.0 9.25 1.23 50.26 20.40 0.293 

12 : 56 : 22 49.0 9.96 1.45 49.75 20.45 0.284 
Straight-Grate 

04/21/94 

H : M : S Time, min 

Wind Box 

SO2 

ppm (wet) 

18 

CO 

ppm (dry) 

Acid Pellets 

NOx 

ppm (wet) 

02 

pct (dry) 

Page 1 of 7 

CO2 

pct (dry) 

9 : 51 : 11 0 6.6 1.01 678.81 16.86 2.48 

9: 52 : 16 1.08 5.9 1.0 610.0 17.25 2.29 

9 : 53 : 21 2.17 5.8 1.0 578.0 17.32 2.23 

9 : 54 : 26 3.25 6.3 1.0 621.8 17.43 2.20 

9: 55 : 31 4.33 

9: 56 : 36 5.42 5.3 1.0 574.1 17.37 2.14 

9: 57 : 41 6.50 6.2 1.0 722.2 17.10 2.37 

9 : 58 : 46 7.58 5.7 1.0 648.3 17.36 2.24 

9: 59 : 51 8.67 6.4 1.0 653.1 17.23 2.30 

10: 0 : 56 9.75 6.4 1.0 701.3 17.20 2.29 

10: 2: 1 10.83 6.0 1.0 759.6 17.02 2.40 

10 : 3 : 6 11.92 6.2 1.0 719.5 17.09 2.36 

10: 4 : 11 13.00 5.7 1.0 737.2 17.09 2.36 

10: 5 : 16 14.08 5.9 1.0 745.1 17.15 2.33 

10: 6 : 21 15.17 5.9 1.0 759.8 16.96 2.43 

10: 7 : 26 16.25 6.4 1.0 694.7 17.14 2.38 

10: 8 : 31 17.33 6.0 1.0 689.2 17.23 2.31 

10: 9 : 36 18.42 6.4 1.0 685.9 17.09 2.35 

10 : 10 : 41 19.50 6.2 1.0 705.8 16.94 2.45 

10 : 11 : 46 20.58 5.8 1.0 752.9 16.97 2.47 

10 : 12 : 51 21.67 6.2 1.0 742.2 17.10 2.38 

10 : 13 : 56 22.75 5.5 1.0 759.1 17.04 2.45 

10 : 15 : 1 23.83 6.1 1.0 725.2 17.09 2.39 

10 : 16 : 6 24.92 5.9 1.0 741.4 17.17 2.37 

10 : 17 : 11 26.00 6.3 1.0 743.9 17.16 2.38 

10 : 18 : 16 27.08 6.1 1.0 680.1 17.44 2.24 

10 : 19 : 21 28.17 4.9 1.0 624.5 17.39 2.23 

10 : 20 : 26 29.25 6.3 1.0 785.5 16.84 2.47 

10 : 21 : 31 30.33 6.5 1.0 785.4 16.83 2.49 

10 : 22 : 36 31.42 6.1 1.0 797.6 16.99 2.45 

10 : 23 : 41 32.50 6.5 1.0 749.5 17.08 2.40 

10 : 24 : 46 33.58 6.0 1.0 652.3 17.41 2.25 

10 : 25 : 51 34.67 6.2 1..0 663.5 17.20 2.34 

10 : 26 : 56 35.75 6.1 1.0 669.8 17.25 2.37 

10 : 28 : 1 36.83 6.7 1.0 711.6 17.23 2.32 

Boxed values are identified as outliers 
Straight-Grate Wind Box 18 Acid Pellets 

04/21/94 SO2 CO NOx 02 

H : M : S Time, min ppm (wet) ppm (dry) ppm (wet) pct (dry) 

Page 2 of 7 

CO2 

pct (dry) 

10 : 29 : 6 37.92 6.2 1.0 701.1 17.13 2.38 

10 : 30 : 11 39.00 5.7 1.0 720.9 17.10 2.40 

10 : 31 : 16 40.08 5.9 1.0 687.8 17.25 2.33 

10 : 32 : 21 41.17 5.2 1.0 643.6 17.31 2.31 

10 : 33 : 26 42.25 5.3 1.0 583.7 17.571 2.19 

10 : 34 : 31 43.33 5.4 1.0 616.2 17.26 2.32 

10 : 35 : 36 44.42 5.4 1.0 577.8 17.53 2.20 

10 : 36 : 41 45.50 5.1 1.0 590.3 17.38 2.26 

10 : 37 : 46 46.58 4.8 1.0 613.3 17.551 2.20 

10 : 38 : 51 47.67 5.4 1.0 645.1 17.46 2.26 

10 : 39 : 56 48.75 5.3 1.0 631.9 17.34 2.31 

10 : 41 : 1 49.83 5.4 1.0 659.1 17.32 2.32 

10 : 42 : 6 50.92 6.0 1.0 647.2 17.40 2.28 

10 : 43 : 11 52.00 5.6 1.0 659.9 17.33 2.32 

10 : 44 : 16 53.08 5.9 1.0 606.1 17.601 2.17 

10 : 45 : 21 54.17 5.5 1.0 631.9 17.34 2.31 

10 : 46 : 26 55.25 5.0 1.0 653.4 17.21 2.38 

10 : 47 : 31 56.33 4.8 1.0 605.7 17.33 2.32 

10 : 48 : 36 57.42 5.1 1.0 571.8 17.47 2.25 

10 : 49 : 41 58.50 5.6 1.0 621.7 • 17.11 2.42 

10 : 50 : 46 59.58 5.8 1.0 662.4 17.11 2.42 

10 : 51 : 51 60.67 5.1 1.0 610.6 17.45 2.27 

10 : 52 : 56 61.75 5.0 1.0 670.1 17.10 2.45 

10 : 54 : 1 62.83 5.6 1.0 681.8 17.11 2.42 

10 : 55 : 6 63.92 

10 : 56 : 11 65.00 4.9 1.0 623.5 17.31 2.32 

10 : 57 : 16 66.08 5.1 1.0 697.0 16.99 2.50 

10 : 58 : 21 67.17 4.9 1.0 637.2 17.34 2.31 

10 : 59 : 26 68.25 4.7 1.0 665.1 17.17 2.41 

11 : 0 : 31 69.33 4.8 1.0 606.6 17.34 2.33 

11 : 1 : 36 70.42 5.3 1.0 603.6 17.40 2.31 

11 : 2 : 41 71.50 5.4 1.0 631.3 17.38 2.29 

11 : 3 : 46 72.58 4.8 1.0 631.3 17.28 2.37 

11 : 4 : 51 73.67 4.8 1.0 587.6 17.29 2.35 

11 : 5 : 56 74.75 5.2 1.0 622.1 17.24 2.39 

Boxed values are identified as outliers 
Straight-Grate Wind Box 18 Acid Pellets 

04/21/94 SO2 CO NOx 02 

H : M : S Time, min ppm (wet) ppm (dry) ppm (wet) pct (dry) 

Page 3 of 7 

CO2 

pct (dry) 

11 : 7 : 1 75.83 4.7 1.0 637.5 17.31 2.34 

11 : 8 : 6 76.92 4.9 1.0 588.1 17.24 2.37 

11 : 9 : 11 78.00 5.2 1.0 662.0 17.18 2.38 

11 : 10 : 16 79.08 5.5 1.0 719.4 17.14 2.42 xxx 

11 : 11 : 21 80.17 5.2 1.0 712.7 17.15 2.42 B 

11 : 12 : 26 81.25 5.2 1.0 704.0 17.13 2.44 E 

11 : 13 : 31 82.33 5.3 1.0 618.5 17.19 2.41 G 

11 : 14 : 36 83.42 4.8 1.0 602.5 17.08 2.48 I 

11 : 15 : 41 84.50 4.7 1.0 590.6 17.03 2.49 N 

11 : 16 : 46 85.58 5.2 1.0 619.0 16.821 2.60 

11 : 17 : 51 86.67 5.1 1.0 630.1 17.04 2.48 L 

11 : 18 : 56 87.75 5.5 1.0 701.8 16.91 2.53 0 

11 : 20 : 1 88.83 5.2 1.0 685.3 17.07 2.47 W 

11 : 21 : 6 89.92 5.3 1.0 678.1 17.07 2.47 

11 : 22 : 11 91.00 5.1 1.0 683.1 16.99 2.51 P 

11 : 23 : 16 92.08 5.0 1.0 711.7 17.04 2.49 R 

11 : 24 : 21 93.17 5.5 1.0 668.5 16.97 2.51 I 

11 : 25 : 26 94.25 4.9 1.0 668.9 17.04 2.48 M 

11 : 26 : 31 95.33 5.4 1.0 654.7 17.00 2.52 A 

11 : 27 : 36 96.42 5.0 1.0 620.6 17.08 2.45 R 

11 : 28 : 41 97.50 5.1 1.0 649.9 17.04 2.49 Y 

11 : 29 : 46 98.58 5.7 1.0 680.5 17.04 2.49 

11 : 30 : 51 99.67 5.8 1.0 661.6 16.99 2.50 A 

11 : 31 : 56 100.75 5.3 1.0 660.9 17.07 2.48 I 

11 : 33 : 1 101.83 5.8 1.0 637.5 17.23 2.40 R 

11 : 34 : 6 102.92 

11 : 35 : 11 104.00 T 

11 : 36 : 16 105.08 5.4 1.0 608.8 17.27 2.36 E 

11 : 37 : 21 106.17 5.6 1.0 654.3 16.94 2.55 S 

11 : 38 : 26 107.25 4.5 1.0 665.6 16.99 2.52 T 

11 : 39 : 31 108.33 4.7 1.0 591.8 17.24 2.39 

11 : 40 : 36 109.42 5.1 1.0 580.0 17.35 2.36 

11 : 41 : 41 110.50 5.7 1.0 562.7 17.38 2.33 

11 : 42 : 46 111.58 4.8 1.0 558.7 17.39 2.34 

11 : 43 : 51 112.67 5.0 1.1 553.9 17.32 2.37 

11 : 44 : 56 113.75 4.4 1.0 579.4 17.27 2.40 

Boxed values are identified as outliers 
Acid Pellets 

CO NOx 

(dry) ppm (wet) 

1.0 

1.0 543.5 

1.0 556.1 

1.0 558.8 

1.0 612.9 

1.0 587.4 

4.0 541.4 

1.0 563.1 

1.0 606.3 

1.0 586.8 

1.0 550.3 

1.0 548.7 

1.0 562.5 

1.0 547.5 

1.0 575.2 

1.5 568.3 

1.0 598.3 

1.0 649.0 

1.0 640.5 

1.0 624.8 

1.0 537.9 

1.0 568.2 

1.0 543.7 

1.0 576.7 

1.0 572.0 

1.0 551.6 

1.0 547.3 

17.35 

17.22 

17.30 

16.97 

17.25 

17.25 

17.17 

17.13 

17.19 

17.21 

17.15 

17.07 

17.31 

17.17 

17.13 

17.15 

16.91 

17.18 

16.96 

17.33 

16.98 

17.22 

17.20 

17.02 

17.25 

17.13 

526.21 17.58 

E 

N 

D 

L 

O 

w 

P 

R 

M 

A 

R 

Y 

Page 4 of 7 

02 CO2 

pct (dry) pct (dry) 

2.24 

2.35 

2.42 

2.38 

2.54 

2.40 

2.40 

2.44 

2.47 

2.42 

2.42 

2.45 

2.49 

2.38 

2.45 

2.49 

2.45 

2.58 

2.46 

2.57 

2.38 

2.55 

2.43 

2.42 

2.52 

2.42 

2.48 

A 

17.04 2.50 R 

16.591 2.72 

17.06 

16.96 

16.85 2.62 

16.75 2.66 

16.79 2.65 

1.6 

1.4 

1.6 

1.2 

1.8 

1.1 

1.7 

544.0 

683.8 

605.5 

611.4 

642.3 

621.2 

644.1 

2.52 T 

2.56 E 

S 

T 

xxx 

Straight-Grate 

04/21/94 

H: M: ST 

Wind Box 18 

SO2 

ime, min ppm (wet) ppm 

11 : 46 : 1 114.83 5.4 

11 : 47 : 6 115.92 5.1 

11 : 48 : 11 117.00 5.4 

11 : 49 : 16 118.08 4.6 

11 : 50 : 21 119.17 5.0 

11 : 51 : 26 120.25 5.0 

11 : 52 : 31 121.33 4.8 

11 : 53 : 36 122.42 5.1 

11 : 54 : 41 123.50 5.6 

11 : 55 : 46 124.58 5.3 

11 : 56 : 51 125.67 4.7 

11 : 57 : 56 126.75 4.5 

11 : 59 : 1 127.83 5.2 

12: 0: 6 128.92 5.1 

12 : 1 : 11 130.00 4.5 

12 : 2 : 16 131.08 4.7 

12: 3 : 21 132.17 4.7 

12 : 4: 26 133.25 4.8 

12: 5 : 31 134.33 4.5 

12: 6 : 36 135.42 4.9 

12: 7 : 41 136.50 4.4 

12 : 8 : 46 137.58 4.6 

12 : 9: 51 138.67 5.3 

12 : 10 : 56 139.75 4.9 

12 : 12 : 1 140.83 4.5 

12 : 13 : 6 141.92 5.1 

12 : 14 : 11 143.00 4.2 

12 : 15 : 16 144.08 

12 : 16 : 21 145.17 

12 : 17 : 26 146.25 4.6 

12 : 18 : 31 147.33 4.7 

12 : 19 : 36 148.42 4.3 

12 : 20 : 41 149.50 4.4 

12 : 21 : 46 150.58 5.4 

12 : 22 : 51 151.67 4.8 

12 : 23 : 56 152.75 4.7 

Boxed values are identified as outliers 
Straight-Grate Wind Box 18 Acid Pellets 

04/21/94 SO2 CO NOx 02 

H : M : S Time, min ppm (wet) ppm (dry) ppm (wet) pct (dry) 

Page 5 of 7 

CO2 

pct (dry) 

12 : 25 : 1 153.83 4.9 1.0 651.5 17.41 2.34 

12 : 26 : 6 154.92 5.6 1.0 668.1 17.12 2.45 

12 : 27 : 11 156.00 4.5 1.0 696.4 17.11 2.48 

12 : 28 : 16 157.08 4.9 1.0 695.9 17.20 2.42 

12 : 29 : 21 158.17 4.9 1.0 691.1 17.15 2.46 

12 : 30 : 26 159.25 5.3 1.0 712.6 17.12 2.48 

12 : 31 : 31 160.33 5.6 1.0 734.5 17.20 2.43 

12 : 32 : 36 161.42 5.3 1.0 729.1 17.28 2.40 

12 : 33 : 41 162.50 4.3 1.0 691.7 17.19 2.44 

12 : 34 : 46 163.58 5.0 1.0 654.2 17.31 2.38 

12 : 35 : 51 164.67 4.6 1.0 594.6 17.52 2.28 

12 : 36 : 56 165.75 4.9 1.0 650.9 17.37 2.36 

12 : 38 : 1 166.83 4.9 1.0 699.5 17.09 2.49 

12 : 39 : 6 167.92 4.8 1.0 719.0 17.21 2.43 

12 : 40 : 11 169.00 5.1 1.0 730.1 17.10 2.48 

12 : 41 : 16 170.08 4.9 1.0 727.5 17.11 2.48 

12 : 42 : 21 171.17 4.7 1.0 707.9 17.18 2.43 

12 : 43 : 26 172.25 4.8 1.0 617.5 17.33 2.36 

12 : 44 : 31 173.33 4.8 1.0 656.5 17.18 2.43 

12 : 45 : 36 174.42 4.6 1.0 728.0 17.18 2.45 

12 : 46 : 41 175.50 5.0 1.0 662.6 17.32 2.37 

12 : 47 : 46 176.58 5.1 1.0 686.3 17.28 2.38 

12 : 48 : 51 177.67 5.0 1.1 638.6 17.41 2.32 

12 : 49 : 56 178.75 4.7 1.0 617.8 17.39 2.33 

12 : 51 : 1 179.83 4.2 1.0 576.1 17.60 2.23 

12 : 52 : 6 180.92 4.7 1.0 625.8 17.47 2.30 

12 : 53 : 11 182.00 5.1 1.0 622.7 17.40 2.33 

12 : 54 : 16 183.08 4.7 1.0 596.7 17.41 2.34 

12 : 55 : 21 184.17 4.9 1.0 587.7 17.41 2.34 

12 : 56 : 26 185.25 5.2 1.0 612.6 17.40 2.36 

12 : 57 : 31 186.33 4.4 1.0 539.1 17.48 2.29 

12 : 58 : 36 187.42 4.3 1.0 613.9 17.21 2.43 

12 : 59 : 41 188.50 4.9 1.0 690.1 17.18 2.44 

Boxed values are identified as outliers 
Straight-Grate Wind Box 18 Acid Pellets 

04/21/94 SO2 CO NOx 

H : M : S Time, min ppm (wet) ppm (dry) ppm (wet) 

02 

pct (dry) 

Page 6 of 7 

CO2 

pct (dry) 

13 : 0 : 46 189.58 4.7 1.0 603.2 17.34 2.37 

13 : 1 : 51 190.67 5.1 1.0 626.7 17.41 2.32 

13 : 2 : 56 191.75 4.8 1.1 623.1 17.23 2.43 

13 : 4 : 1 192.83 

13 : 5 : 6 193.92 4.6 1.5 652.4 17.34 2.39 

13 : 6 : 11 195.00 4.7 1.2 676.7 17.32 2.40 

13 : 7 : 16 196.08 4.5 1.7 621.1 17.31 2.38 

13 : 8 : 21 197.17 4.7 1.0 607.9 17.45 2.31 

13 : 9: 26 198.25 4.4 1.0 644.1 17.32 2.37 

13 : 10 : 31 199.33 5.1 1.3 711.8 17.03 2.53 

13 : 11 : 36 200.42 5.3 1.0 714.3 17.14 2.46 

13 : 12 : 41 201.50 4.6 1.2 745.3 17.05 2.52 

13 : 13 : 46 202.58 4.7 1.1 760.9 17.12 2.47 

13 : 14 : 51 203.67 5.0 1.0 700.3 17.27 2.40 

13 : 15 : 56 204.75 4.8 1.0 673.3 17.27 2.40 

13 : 17 : 1 205.83 4.9 1.1 663.6 17.22 2.41 

13 : 18 : 6 206.92 4.1 1.0 661.5 17.38 2.35 

13 : 19 : 11 208.00 4.4 1.4 613.5 17.52 2.28 

13 : 20 : 16 209.08 5.0 1.0 639.9 17.34 2.37 

13 : 21 : 21 210.17 4.0 1.0 636.2 17.28 2.40 

13 : 22 : 26 211.25 5.0 1.1 705.5 17.14 2.45 

13 : 23 : 31. 212.33 5.0 1.1 697.0 17.11 2.48 

13 : 24 : 36 213.42 4.8 1.1 637.0 17.42 2.33 

13 : 25 : 41 214.50 5.1 1.0 654.7 17.43 2.30 

13 : 26 : 46 215.58 4.7 1.0 685.5 17.28 2.37 

13 : 27 : 51 216.67 4.3 1.4 668.1 17.19 2.44 

13 : 28 : 56 217.75 4.7 1.0 649.4 17.33 2.37 

13 : 30 : 1 218.83 4.4 1.4 685.8 17.29 2.39 

13 : 31 : 6 219.92 4.8 1.2 785.5 16.95 2.55 

13 : 32 : 11 221.00 4.9 1.0 722.7 17.03 2.51 

13 : 33 : 16 222.08 4.8 1.0 687.1 17.23 2.40 

Boxed values are identified as outliers 
Straight-Grate Wind Box 18 Acid Pellets 

04/21/94 SO2 CO NOx 02 

H : M : S Time, min ppm (wet) ppm (dry) ppm (wet) pct (dry) 

Page 7 of 7 

CO2 

pct (dry) 

13 : 34 : 21 223.17 4.7 1.1 650.2 17.32 2.36 

13 : 35 : 26 224.25 4.6 1.2 699.8 17.25 2.41 

13 : 36 : 31 225.33 4.7 1.0 644.3 17.42 2.31 

13 : 37 : 36 226.42 4.8 1.1 673.8 17.35 2.35 

13 : 38 : 41 227.50 4.6 1.3 713.4 17.27 2.40 

13 : 39 : 46 228.58 4.6 1.2 717.6 17.13 2.46 

13 : 40 : 51 229.67 4.4 1.3 667.0 17.25 2.41 

13 : 41 : 56 230.75 4.7 1.4 692.5 17.23 2.43 

13 : 43 : 1 231.83 4.3 1.5 674.1 17.28 2.39 

13 : 44 : 6 232.92 4.8 1.3 646.8 17.31 2.37 

13 : 45 : 11 234.00 4.2 1.4 643.2 17.21 2.42 

13 : 46 : 16 235.08 

13 : 47 : 21 236.17 

13 : 48 : 26 237.25 4.8 1.0 630.5 17.18 2.46 

13 : 49 : 31 238.33 4.5 1.0 663.7 17.39 2.33 

13 : 50 : 36 239.42 4.9 1.0 653.4 17.38 2.33 
APPENDIX C 
Grate-Kiln Port 6a Fluxed 

09/28/93 NO NOx SO2 CO 02 CO2 

Hr : Mn Time ppm (wet) ppm (wet) ppm (wet) ppm (dry) % (dry) % (dry) 

10 : 25 0 140.0 145.0 5.0 11.0 18.3 2.10 

10 : 30 5 140.0 140.0 3.0 9.0 18.4 2.05 

10 : 35 10 130.0 137.0 4.0 6.0 18.6 1.80 

10 : 40 15 115.0 115.0 5.0 4.0 18.8 1.65 

UpSet 

10 : 50 25 67.0 67.0 2.0 0.0 19.4 1.00 

ShutDown 

13 : 5 160 85.0 85.0 3.0 4.5 19.1 1.50 

13 : 12 167 85.0 85.0 2.0 4.0 19.2 1.45 

13 : 19 174 80.0 80.0 2.0 4.0 19.2 1.45 

13 : 29 184 77.0 77.0 1.0 2.0 19.4 1.20 

13: 40 195 75.0 75.0 2.0 3.0 19.1 1.40 

13 : 50 205 105.01 105.0 2.0 1.0 19.2 1.60 

14 : 0 215 85.0 85.0 0.0 0.0 19.4 1.10 

14 : 10 225 70.0 70.0 0.0 0.0 19.6 0.95 

14 : 20 235 65.0 65.0 0.0 0.0 19.8 0.90 

14 : 30 245 60.0 60.0 0.0 0.0 19.8 0.75 

14: 40 255 55.0 55.0 0.0 0.0 19.9 0.75 

14 : 50 265 50.0 50.0 0.0 0.0 20.0 0.70 

15 : 0 275 50.0 50.0 0.0 0.0 20.0 0.70 

15 : 10 285 45.0 45.0 0.0 0.0 20.0 0.60 

15: 20 295 50.0 50.0 0.0 0.0 20.1 0.60 

15 : 30 305 45.0 45.0 0.0 0.0 20.1 0.65 

15 : 40 315 50.0 50.0 0.0 0.0 20.1 0.65 

15 : 53 328 45.0 45.0 0.0 0.0 20.1 0.60 

16 : 10 345 40.0 40.0 0.0 0.0 20.2 0.55 

16 : 20 355 40.0 40.0 0.0 0.0 19.9 0:70 

16 : 40 375 34.0 34.0 0.0 0.0 20.1 0.10 

17 : 0 395 40.0 40.0 0.0 0.0 20.1 0.60 

17 : 20 415 41.0 41.0 0.0 0.0 20.2 0.55 

17 : 35 430 32.5 32.5 0.0 0.0 20.2 0.50 

17 : 45 440 37.0 37.0 0.0 0.0 20.2 0.55 

18 : 0 455 35.5 35.5 0.0 0.0 20.2 0.50 

18 : 15 470 37.5 38.0 0.0 0.0 20.2 0.46 

18 : 30 485 35.0 35.0 0.0 0.0 20.3 0.45 

Boxed values are identified as outliers 
Grate-Kiln 

09/28/93 

Hr : Mn 

Port 6 Fluxed 

Time NOx SO2 CO 

min ppm (wet) ppm (wet) ppm (dry) 

02 

pct (dry) 

CO2 

pct (dry) 

13 : 5 160 85.00 3.00 4.50 19.10 1:50 

13 : 12 167 88.44 2.08 4.16 19.16 1.51 

13 : 19 174 86.48 2.16 4.32 19.13 1.57 

13 : 29 184 87.70 1.14 2.28 19.28 1.37 

13 : 40 195 90.20 2.41 3.61 18.94 1.68 

13 : 50 205 2.52 1.26 19.01 

14 : 0 215 112.07 0 0 19.17 1.45 

14 : 10 225 96.34 0 0 19.34 1.31 

14 : 20 235 93.22 0 0 19.51 1.29 

14 : 30 245 89.53 0 0 19.48 1.12 

14 : 40 255 85.25 0 0 19.56 1.16 

14 : 50 265 80.40 0 0 19.63 1.13 

15 : 0 275 83.29 0 0 19.61 1.17 

15 : 10 285 77.57 0 0 19.59 1.03 

15 : 20 295 89.08 0 0 19.67 1.07 

15 : 30 305 82.78 0 0 19.65 1.20 

15 : 40 315 94.87 0 0 19.64 1.23 

15 : 53 328 88.77 0 0 19.62 1.18 

16 : 10 345 82.84 0 0 19.69 1.14 

16 : 20 355 85.16 0 0 19.39 1.49 

16 : 40 375 76.32 0 0 19.56 

17 : 0 395 94.42 0 0 19.54 1.42 

17 : 20 415 101.53 0 0 19.62 1.36 

17 : 35 430 83.30 0 0 19.61 1.28 

17 : 45 440 96.98 0 0 19.60 1.44 

18 : 0 455 96.13 0 0 19.59 1.35 

18 : 15 470 106.20 0 0 19.58 1.27 

18 : 30 485 100.86 0 0 19.66 1.30 

Data corrected for sample line air leak 
Grate-Kiln 

09/30/93 

Hr : Mn 

Port 6b Fluxed 

NO NOx SO2 CO 

Time ppm (wet) ppm (wet) ppm (wet) ppm (dry) 

02 

% (dry) 

CO2 

% (dry) 

11 : 42 0 235 235 21 19.0 17.0 3.10 

11 : 45 3 242 242 22 19.0 17.11 3.05 

11 : 55 13 3651 365 15 20.0 16.7 3.25 

12 : 0 18 270 270 15 18.5 16.8 3.25 

12 : 5 23 260 260 12 19.5 16.8 3.25 

12 : 8 26 260 260 12 27.0 16.7 3.35 

12 : 29 47 260 260 12 23.5 16.8 3.25 

12 : 31 49 270 270 10 25.0 16.8 3.25 

12 : 46 64 240 240 20 19.0 16.8 3.20 

12 : 48 66 240 240 21 25.0 16.8 3.15 

12 : 51 69 240 240 30 17.0 16.8 3.20 

12: 59 77 240 240 38 22.0 16.8 3.22 

13 : 0 78 240 240 38 18.0 16.8 3.22 

13 : 2 80 240 240 35 24.0 16.7 3.25 

13 : 5 83 240 240 35 21.0 16.7 3.25 

13 : 7 85 250 250 35 22.0 16.7 3.25 

13: 10 88 240 240 35 19.0 16.7 3.25 

13 : 13 91 240 240 35 21.0 16.7 3.25 

13: 15 93 245 245 35 20.0 16.7 3.25 

13 : 18 96 240 240 35 21.0 16.7 3.25 

13: 22 100 240 240 15 19.0 16.7 3.25 

13 : 31 109 240 240 35 28.0 16.7 3.25 

13 : 38 116 245 245 151 30.0 16.5 3.35 

13 : 40 118 240 240 12 27.0 16.5 , 3.32 

13 : 50 128 240 240 40 25.0 16.7 3.25 

13 : 52 130 240 240 35 25.0 16.7 3.20 

13 : 55 133 245 245 32 24.0 16.7 3.25 

13: 57 135 245 245 20 22.0 16.7 3.25 

14: 2 140 230 230 15 22.0 16.7 3.23 

14 : 7 145 240 240 40 26.0 16.6 3.23 

14 : 13 151 250 250 32 28.0 16.6 3.30 

14 : 17 155 245 245 25 25.0 16.6 3.28 

14 : 25 163 280 280 45 27.0 16.7 3.23 

14 : 30 168 280 280 35 27.0 16.9 3.15 

14 : 35 173 255 255 28 27.0 16.9 3.10 

14 : 40 178 255 255 18 25.0 16.9 3.08 

14 : 50 188 265 265 40 23.0 17.0 3.07 

15 : 0 198 260 260 25 25.0 16.9 3.10 

15 : 15 213 260 260 40 19.0 17.0 3.05 

Boxed values are identified as outliers 
Grate-Kiln 

10/04/93 

Hr : Mn Time 

Port 5B Fluxed 

NO NOx SO2 CO 

ppm (wet) ppm (wet) ppm (wet) ppm (dry) 

02 

% (dry) 

CO2 

% (dry) 

10 : 46 0 4931 6901 4601 501 20.01 4.63 

12 : 45 119 380 390 110 20 15.4 4.30 

12 : 50 124 420 420 118 20 15.0 4.50 

13 : 0 134 420 420 100 25 15.2 4.30 

13 : 10 144 415 415 122 35 15.2 4.30 

13 : 15 149 385 385 125 31 15.2 4.25 

13 : 20 154 400 400 118 36 14.8 4.60 

13 : 30 164 400 400 130 30 15.3 4.10 

13 : 40 174 410 410 130 32 15.2 4.30 

13 : 50 184 390 390 105 36 15.0 4.45 

13 : 55 189 400 400 100 38 15.0 4.42 

14 : 0 194 410 410 108 37 15.0 4.40 

14 : 15 209 400 400 112 33 15.0 4.40 

14 : 25 219 385 385 140 28 15.2 4.15 

14 : 38 232 360 360 105 37 15.4 4.25 

14 : 48 242 400 400 120 30 15.5 4.05 

14 : 55 249 380 380 95 38 15.4 4.15 

15 : 0 254 380 380 100 35 15.2 4.25 

15 : 2 256 420 420 100 38 14.9 4.45 

15 : 5 259 395 395 100 25 15.3 4.15 

15 : 10 264 380 380 85 20 15.6 4.08 

15 : 15 269 365 365 90 19 15.5 4.08 

15 : 20 274 360 360 90 18 15.8 3.85 

15 : 25 279 370 370 85 18 15.8 4.00 

15 : 30 284 370 370 95 18 16.0 3.85 

Boxed values are identified as outliers 
Grate-Kiln 

10/05/93 

Hr : Mn 

Port 4 Fluxed 

NO NOx 

Time ppm (wet) ppm (wet) ppm 

SO2 CO 

(wet) ppm (dry) 

02 

% (dry) 

CO2 

% (dry) 

11 : 40 0 785 785 270 104.0 12.0 4.55 

11 : 45 5 780 780 290 5.0 'F1.8 4.75 

11 : 50 10 740 740 235 0.0 11.6 4.50 

11 : 55 15 770 770 235 2.0 11.5 4.40 

12 : 5 25 780 780 300 4.0 12.2 4.30 

12 : 24 44 720 720 255 2.0 12.0 4.40 

12 : 28 48 760 760 260 2.0 11.8 4.65 

12 : 42 62 720 720 240 2.0 12.0 4.50 

12 : 45 65 680 680 261 3.0 12.3 4.35 

12 : 50 70 760 760 270 8.01 10.5 5.00 

12 : 55 75 740 740 260 8.0 11.2 5.60 

13 : 0 80 780 780 250 15.0 11.8 4.60 

13 : 5 85 760 760 259 20.0 12.3 5.10 

13 : 15 95 760 760 230 25.0 11.8 5.50 

13 : 28 108 790 790 265 15.0 11.0 5.30 

13 : 33 113 760 760 230 11.0 11.6 5.20 

13 : 40 120 740 740 255 15.0 11.4 4.80 

13 : 49 129 790 790 235 9.0 11.8 4.60 

14 : 16 156 820 820 240 11.0 11.4 4.50 

14 : 24 164 810 810 225 25.0 11.0 5.00 

14 : 32 172 800 800 235 20.0 10.8 5.00 

14 : 47 187 720 720 250 5.0 11.5 4.40 

14 : 50 190 660 660 220 3.0 12.3 4.30 

15 : 0 200 6501 6501 200 2.0 12.4 4.20 

15 : 6 206 680 680 210 1.0 12.5 4.10 

15 : 12 212 700 700 220 1.0 12.2 4.20 

Boxed values are identified as outliers 
Grate-Kiln 

10/06/93 

Hr : Mn 

Port 3 Fluxed 

NO NOx SO2 CO 

Time ppm (wet) ppm (wet) ppm (wet) ppm (dry) 

02 

% (dry) 

CO2 

% (dry) 

12 : 35 0 500 500 170 16.5' 2.3 

12 : 40 5 540 540 200 16.0 2.3 

12 : 45 10 530 530 200 15.7 2.3 

12 : 50 15 490 490 170 15.7 2.3 

12 : 55 20 520 520 220 15.7 2.4 

13 : 0 25 520 520 220 15.4 2.4 

13 : 5 30 560 560 220 15.4 2.4 

13 : 10 35 520 520 230 15.3 2.5 

13 : 15 40 580 580 240 15.5 2.3 

13 : 20 45 540 540 240 15.4 2.4 

13 : 25 50 520 520 180 15.5 2.2 

13 : 30 55 540 540 190 15.5 2.2 

13: 35 60 590 590 230 15.3 2.6 

13 : 45 70 520 520 190 15.6 2.4 

13 : 55 80 540 540 190 15.6 2.5 

14 : 0 85 510 510 190 15.6 2.5 

14 : 5 90 530 530 180 15.8 2.2 

14 : 7 92 500 500 180 0.10 15.9 2.2 

14 : 15 100 540 540 160 0.15 15.3 2.5 

14 : 20 105 500 500 150 0.20 15.4 2.4 

14 : 25 110 520 520 200 15.4 2.4 

14 : 30 115 550 550 200 15.1 2.4 

14 : 35 120 520 520 180 15.2 2.4 

14 : 40 125 520 540 180 0.10 15.5 2.2 

14 : 45 130 510 530 200 0.10 15.1 2.4 

14 : 50 135 530 560 180 0.20 15.4 2.4 

14 : 55 140 460 550 190 0.20 15.4 2.5 

15 : 0 145 440 440 160 0.30 15.2 3.0 

15 : 8 153 440 490 150 0.30 15.0 2.7 

15 : 12 157 420 420 160 0.40 14.4 2.5 

15 : 15 160 440 440 160 0.30 15.4 2.7 

15 : 20 165 450 440 155 0.30 15.4 2.9 

15 : 25 170 420 460 155 0.30 14.6 2.4 

15 : 30 175 430 420 155 0.30 15.1 2.5 

15 : 35 180 440 430 155 0.30 15.4 2.4 

15 : 40 185 420 430 158 0.30 14.9 2.7 

15 : 45 190 440 440 165 0.30 14.6 2.8 

15 : 50 195 460 480 150 0.30 15.3 2.4 

15 : 55 200 460 440 160 0.30 15.1 2.6 

16 : 0 205 460 450 160 0.30 15.2 2.6 

16 : 5 210 440 450 160 0.20 14.9 2.5 

16 : 10 215 450 460 155 0.10 14.9 2.6 

16 : 15 220 440 420 155 0.10 15.2 2.5 

16 : 20 225 410 430 150 0.10 15.9 2.2 

16 : 25 230 380 380 145 0.10 10.2 2.2 

16 : 30 235 2601 280 145 0.10 15.6 2.3 

Boxed values are identified as outliers 
Grate-Kiln Port 1 Fluxed 

10/07/93 NO NOx SO2 CO 02 CO2 

Hr : Mn Time ppm (wet) ppm (wet) ppm (wet) ppm (dry) % (dry) % (dry) 

14: 6 0 350 0 19.40 0 

14 : 15 9 3.50 3.50 330 0 19.30 0 

14 : 19 13 3.50 3.50 320 0 19.20 0 

14 : 20 14 3.50 4.00 230 0 19.10 0 

14 : 35 29 4.00 4.00 560 0 18.90 0 

14 : 40 34 4.00 4.00 410 0 18.90 0 

14 : 45 39 4.25 4.25 250 0 19.20 0 

14 : 48 42 4.00 4.00 450 0 18.90 0 

14 : 53 47 4.25 4.50 410 0 18.80 0 

14 : 55 49 4.00 4.25 340 0 18.70 0 

14 : 58 52 4.25 4.50 380 0 18.70 0 

15 : 3 57 4.25 4.50 340 0 18.80 0 

15 : 5 59 4.25 4.50 300 0 18.90 0 

15 : 8 62 4.25 4.50 260 0 19.00 0 

15 : 15 69 4.25 4.50 380 0 18.80 0 

15 : 25 79 4.50 4.50 370 0 18.70 0 

15 : 35 89 4.25 4.50 300 0 19.00 0 

15 : 45 99 4.25 4.50 200 0 19.10 0 

16 : 0 114 4.25 4.25 310 0 19.00 0 

16 : 5 119 4.20 4.20 310 0 19.25 0 

16 : 14 128 4.00 4.25 130 0 19.30 0 

16 : 20 134 4.00 4.25 240 0 19.00 0 

16 : 25 139 4.00 4.25 240 0 19.00 0 

16 : 30 144 4.00 4.25 280 0 19.00 0 

16 : 31 145 4.00 4.25 410 0 18.70 0 

16 : 33 147 4.00 4.25 210 0 19.20 0 

16 : 35 149 4.00 4.25 190 0 19.20 0 

16 : 41 155 4.00 4.25 180 0 19.20 0 

16 : 43 157 4.00 4.25 200 0 19.10 0 

16 : 45 159 4.00 4.25 300 0 18.80 0 

16 : 50 164 4.00 4.25 185 0 19.20 0 

16 : 54 168 3.75 4.00 145 0 19.20 0 

16 : 56 170 3.75 4.00 115 0 19.20 0 

16 : 57 171 4.00 4.00 250 0 18.70 0 

16 : 59 173 4.00 4.25 150 0 19.20 0 

17 : 0 174 3.75 4.00 130 0 19.20 0 

Special test of air outside of Port #1 

17 : 2 176 3.75 4.00 170 0 19.20 0 

17 : 5 179 4.00 4.00 165 0 19.20 0 

17 : 7 181 4.00 4.00 150 0 19.40 0 

17 : 8 182 3.75 4.00 140 0 19.20 0 

17 : 9 183 3.75 4.00 50 0 20.10 0 

17 : 12 186 3.75 4.00 0 0 20.20 0 

Boxed values are identified as outliers 
Grate-Kiln Port 2 Fluxed 

10/08/93 NO NOx SO2 CO 02 CO2 

Hr : Mn Time ppm (wet) ppm (wet) ppm (wet) ppm (dry) % (dry) % (dry) 

9: 45 0 4.50 4.50 5 1.50 20.6 0.04 

10 : 0 15 3.50 3.00 0 0.10 20.6 0.04 

10 : 15 30 3.50 3.75 0 0.00 20.5 0.04 

10: 20 35 3.50 3.50 0 0.00 20.6 0.04 
APPENDIX D 
Straight-Grate 

29/Nov/93 

H : M : S Time,min 

WB 6 

SO2 

ppm(wet) 

Fluxed Pellets 

CO NOx 

ppm(d ry) ppm(wet) 

02 

pct(dry) 

CO2 

pct(dry) 

13 : 51 : 44 -0.00 2.53 <3 41.71 20.25 

13 : 54 : 44 3.00 4.11 <3 46.6 20.31 0.50 

13 : 57 : 44 6.00 3.71 <3 45.5 20.36 

14: 0 : 44 9.00 3.39 <3 44.8 20.29 

14 : 3 : 44 12.00 5.10 <3 52.9 20.24 

14 : 6 :44 15.00 6.61 <3 47.1 20.32 0.60 

14: 9 : 44 18.00 4.87 <3 45.5 20.39 

14 : 12 : 44 21.00 4.06 <3 48.4 20.38 

14 : 15 : 44 24.00 5.92 <3 51.2 20.37 0.50 

14 : 18 : 44 27.00 6.59 <3 51.7 20.29 

14 : 21 : 44 30.00 5.62 <3 47.7 20.37 0.58 

14 : 24 : 44 33.00 5.68 <3 44.4 20.43 

14 : 27 : 44 36.00 5.84 <3 47.3 20.45 

14 : 30 : 44 39.00 7.19 <3 46.7 20.49 

14 : 33 : 44 42.00 6.40 <3 47.6 20.46 0.50 

14 : 36 : 44 45.00 7.49 <3 51.4 20.43 

14 : 39 : 44 48.00 6.96 <3 48.7 20.47 

14 : 42 : 44 51.00 5.43 <3 44.9 20.45 

14 : 45 : 44 54.00 5.27 <3 45.6 20.51 0.40 

14 : 48 : 44 57.00 4.99 <3 49.4 20.49 

DATA LOGGER LOCK 

14 : 53 : 51 62.12 5.27 <3 44.8 20.45 

14 : 56 : 51 65.12 5.81 <3 45.9 20.45 0.50 

14 : 59 : 51 68.12 4.46 <3 44.8 20.48 

15: 2 : 51 71.12 4.69 <3 45.8 20.47 

15 : 5 : 51 74.12 4.35 <3 47.1 20.43 

15 : 8 : 51 77.12 5.57 <3 53.5 20.33 

15 : 11 : 51 80.12 5.45 <3 52.5 20.37 0.58 

15 : 14 : 51 83.12 5.40 <3 48.6 20.40 

15 : 17 : 51 86.12 4.89 <3 51.8 20.41 

15 : 20 : 51 89.12 5.86 <3 49.8 20.45 

15 : 23 : 51 92.12 4.16 <3 51.4 20.40 

15 : 26 : 51 95.12 5.63 <3 54.0 20.37 

15 : 29 : 51 98.12 6.57 <3 54.1 20.38 

15 : 32 : 51 101.12 5.42 <3 49.4 20.38 0.59 

Boxed values are identified as outliers 
Straight-Grate WB 10 Fluxed Pellets 

30/Nov/93 SO2 CO 

H : M : S Time,min ppm(wet) ppm(dry) ppm(wet) 

NOx 02 

pct(dry) 

CO2 

pct(dry) 

15 : 56 : 28 -0.00 35.75 ND 198.4 17.831 2.25 

15 : 59 : 28 3.00 36.95 ND 180.1 17.91 

16 : 2 : 28 6.00 39.71 ND 182.2 17.97 2.25 

16 : 5 : 28 9.00 33.87 ND 188.2 17.98 

16 : 8 : 28 12.00 35.05 ND 174.7 18.14 

16 : 11 : 28 15.00 33.74 ND 180.6 18.17 2.10 

16 : 14 : 28 18.00 33.15 ND 169.2 18.19 2.10 

16 : 17 : 28 21.00 31.14 ND 160.8 18.23 

16 : 20 : 28 24.00 43.08 ND 190.9 18.03 

16 : 23 : 28 27.00 38.29 ND 182.6 18.03 

16 : 26 : 28 30.00 33.66 ND 173.9 18.09 2.20 

16 :29 : 28 33.00 32.75 ND 178.8 18.15 

16 : 32 : 28 36.00 34.29 ND 170.3 18.24 2.05 

16 : 35 : 28 39.00 31.73 ND 154.0 18.33 

16 : 38 : 28 42.00 33.38 ND 154.4 18.36 

16 : 41 :28 45.00 33.34 ND 157.2 18.42 1.801 

16 : 44 : 28 48.00 29.77 ND1 149.01 18.45 

16 : 47 : 28 51.00 38.94 ND 187.2 18.07 

16 : 50 : 28 54.00 38.40 ND 187.8 18.08 2.30 

16 : 53 : 28 57.00 38.76 ND 175.7 18.19 

16 : 56 : 28 60.00 33.83 ND 175.7 18.15 2.20 

Boxed values are identified as outtiers 
Straight-Grate 

1/Dec/93 

H : M : S Time,min 

WB 12 

SO2 

ppm(wet) 

Fluxed Pellets 

CO NOx 

ppm(dry) ppm(wet) 

02 

pct(dry) 

CO2 

pct(dry) 

13 : 54 : 23 0.00 8.13 ND 532.7 18.06 1.94 

13 : 57 : 23 3.00 7.20 ND 497.1 18.20 1.94 

14 : 0 : 23 6.00 7.98 ND 557.6 18.13 

14 : 3 : 23 9.00 6.53 ND 480.6 18.20 

14 : 6 : 23 12.00 9.39 ND 588.0 17.67 2.20 

14 : 9 : 23 15.00 9.77 ND 732.4 17.09 2.45 

14 : 12 : 23 18.00 10.50 ND 733.6 17.28 2.70 

14 : 15 : 23 21.00 11.56 ND 728.0 17.43 2.60 

14 : 18 : 23 24.00 8.07 ND 811.8 17.31 

14 : 21 : 23 27.00 9.13 ND 839.5 16.95 

14 : 24 : 23 30.00 7.60 ND 900.0 16.67 

14 : 27 : 23 33.00 8.11 ND 802.1 16.79 3.10 

14 : 30 : 23 36.00 9.08 ND 780.9 16.92 

14 : 33 : 23 39.00 7.67 ND 823.5 16.86 2.95 

14 : 36 : 23 42.00 6.00 ND 730.0 17.21 

14 : 39 : 23 45.00 6.04 ND 716.0 17.12 2.86 

14 : 42 : 23 48.00 6.01 ND 708.7 17.14 

14 : 45 : 23 51.00 7.45 ND 771.1 16.83 2.95 

14 : 48 : 23 54.00 7.94 ND 726:9 16.94 3.00 

14 : 51 : 23 57.00 7.43 ND 750.9 16.84 

14 : 54 : 23 60.00 7.12 ND 700.6 17.12 2.90 

14 : 57 : 23 63.00 6.31 ND 643.8 17.23 

15 : 0 : 23 66.00 7.09 ND 567.2 17.45 

15 : 3 : 23 69.00 6.36 ND 557.5 17.53 

15 : 6 : 23 72.00 6.05 ND 531.3 17.65 

15 : 9 : 23 75.00 7.04 ND 555.4 17.63 2.45 

15 : 12 : 23 78.00 6.73 ND 499.0 17.82 

15 : 15 : 23 81.00 6.75 ND 533.9 17.83 

15 : 18 : 23 84.00 7.80 ND 576.5 17.74 

15 : 21 : 23 87.00 7.08 ND 568.2 17.71 2.40 

15 : 24 : 23 90.00 8.81 ND 529.3 17.60 

15 : 27 : 23 93.00 8.88 ND 532.8 17.43 2.70 

15 : 30 : 23 96.00 9.29 ND 596.0 17.48 

15 : 33 : 23 99.00 9.31 ND 605.5 17.60 

15 : 36 : 23 102.00 5.91 ND 527.4 18.16 

15 : 39 : 23 105.00 5.58 ND 483.8 18.38 2.03 

15 : 42 : 23 108.00 6.72 ND 475.4 17.96 

15 : 45 : 23 111.00 8.60 ND 466.2 18.05 

15 : 48 : 23 114.00 9.19 ND 477.0 18.04 

15 : 51 : 23 117.00 5.59 ND 399.4 18.39 

15 : 54 : 23 120.00 5.21 ND 453.6 18.42 1.82 

15 : 57 : 23 123.00 5.18 ND 464.2 18.34 1.70 

Boxed values are identified as oultiers 
Straight-Grate WB 26 Fluxed Pellets 

2/Dec/93 SO2 CO NOx 02 CO2 

H : M : S Time,min ppm(wet) ppm(dry) ppm(wet) pct(dry) pct(dry) 

10 : 42 : 27 -0.00 28.50 ND 14.1 20.73 

10 : 45 : 27 3.00 8.20 ND 16.5 20.76 0.05 

10 : 48 : 27 6.00 1.10 ND 17.5 20.89 

10 : 51 :27 9.00 1.74 ND 18.5 20.84 0.04 

10 : 54 : 27 12.00 4.75 ND 19.2 20.85 

10 : 57 : 27 15.00 4.07 ND 19.4 20.85 0.05 

11 : 0 : 27 18.00 8.74 ND 18.8 20.86 

11 : 3 : 27 21.00 5.73 ND 18.2 20.84 

11 : 6 : 27 24.00 6.99 ND 17.0 20.84 

11 : 9 : 27 27.00 4.89 ND 16.3 20.82 

11 : 12 : 27 30.00 3.50 ND 15.4 20.81 0.03 

11 : 15 : 27 33.00 3.48 ND 14.6 20.83 

11 : 18 : 27 36.00 16.04 ND 14.4 20.68 

11 :21 :27 39.00 34.18 ND 14.3 20.64 

11 : 24 : 27 42.00 19.13 ND 13.7 20.75 

11 : 27 : 27 45.00 21.82 ND 13.0 20.71 

11 : 30 : 27 48.00 21.28 ND 12.3 20.67 0.05 

11 :33 : 27 51.00 24.21 ND 11.8 20.62 

11 : 36 : 27 54.00 21.24 ND 11.5 20.57 0.10 

11 : 39 : 27 57.00 23.92 ND 10.9 20.60 

11 :42 : 27 60.00 27.03 ND 10.9 20.51 0.05 

11 : 45 : 27 63.00 16.66 ND 10.3 20.74 

11 : 48 : 27 66.00 10.04 ND 10.1 20.80 0.05 

11 :51 :27 69.00 17.01 ND 9.9 20.77 

11 :54 : 27 72.00 24.99 ND 9.6 21.04 

11 : 57 : 27 75.00 32.98 ND 9.6 20.46 0.101 

12 : 0 : 27 78.00 11.22 ND 9.4 20.96 

Boxed values are identified as oultiers 

SO2 @3-33 & 36-78 min tested separately for outliers