# Class I Air Modeling Report
Keetac Expansion Project Prepared for U.S. Steel



## December 2010



# BARR

# 2. Project Description

Currently, Keetac has one operational pellet producing line (Line 2, also referred to as the existing line) with an annual production of approximately 6.0 million net tons per year. U. S. Steel proposes to increase the capacity at the Keetac facility by restarting a second pellet producing line (Line 1, also referred to as the new line). The restart would involve energy-efficient teclmologies in addition to new emission controls to exceed current enviromnental standards. The expansion would increase Keetac's iron pellet production output by 3.6 million tons to a total annual output of9.6 million tons. This project is referred to as the "Keetac Expansion Project". Upgrades to the mining, concentrating and agglomerating processes would support the increased production requirements. The project will also include the purchase of additional mining equipment and the installation of additional processing equipment.
Air Emissions The project will generate air emissions, including off-road mobile source emissions. As part of the air permit, Keetac will take a NOx limit to net out ofPSD requirements for NOx. Keetac will be able to comply with the NOx emission limit by using a mixture of natural gas and biomass, coal, or fuel oil. The netting evaluation is shown in Attachment E. Since there is no significant increase in NOx emissions the project is not subject to PSD requirements to evaluate NOx for increment consumption and NAAQS. However, the total facility NOx emissions are included in the evaluation to capture chemical interactions with ammonia. In addition, the FLM's have requested that NOx emissions be included in an evaluation that compares the change in modeled visibility impacts from the facility baseline period to the expansion project combined with the existing facility. NOx emissions will be included with the other pollutants including PM 10 and S0 2 for this evaluation. Total emissions modeled are described in Attachment B.

As discussed with the FLM's and MPCA, Keetac is running a variety of modeling scenarios 

### as described in the protocol, which includes a scenario comparing the emissions representative ofKeetac's baseline period compared to emissions from the total post project facility. The emissions from these two operating scenarios will be used as inputs into the modeling. The differences will be paired in time and space. 

## 2.1 Baseline Period Modeling (Pre-Scrubber)
Keetac is pennitting the stationary source NOx emissions for the expansion project as a minor modification by netting emissions with the existing line. In the 10 year period preceding this project, natural gas was the primary fuel used in the existing line and was the basis for determining a NOx baseline value. A 24-month baseline period of November 1999 through October 2001 was chosen to

Page 3represent baseline emissions for the netting evaluation. Therefore the baseline emissions will be calculated using emission factors from the Keetac Phase II Stack Tests July 25-26, 2000 Stack Test for S0 2 and NOx. These tests were used because the emission factors from that time are most representative of the indurating process operating conditions for the baseline period. This time period and the emission factors used in the netting analysis were reviewed and approved by the MPCA. The MPCA's emission inventory rules allow the use of an emission factor derived from a stack test for a period of ten years after the test). Additionally, the MPCA has already used these results from the July 2000 NOx test in the netting calculations for the permit that authorized construction of the scrubber and fuel switch in 2005 at Keetac. The emission factor for PM 10 was derived fi·om a stack test performed in July 2000. The baseline emissions are summarized by emission group and shown in the Class I Modeling Protocol (November 2008) (see Attachment A). 

## 2.2 Final Proposed Facility
A couple of changes have occurred at the facility since the timeframe associated with the baseline period. Understanding and tracking these changes is necessary to define the final proposed facility emissions.
Post-Scrubber/Fuel Switch Emissions Calculation of post scrubber emissions relies on stack test emission factors from two tests at the existing Keetac pellet line, one using coal as the primary fuel and one using natural gas as the primary fuel (NOx Test Oct 19, 2005 -NG Basis, NOx Test May 31-June 1 2006- Coal Basis). The installation of the scrubber in October 2005 also changed the dispersion characteristics for emissions from the existing Phase II furnace. Prior to installation of the scrubber there were two stacks on the existing indurating furnace. With the installation of the scrubber these two streams were routed to a scrubber with a single stack. This modification of the exhaust streams also resulted in changes to the flow patterns in the furnace. Following installation of the scrubber two stack tests were conducted, one in 2005 while firing natural gas and a second in 2006 while firing coal. Therefore, these stack tests are appropriate to use for calculating the emissions for the post scrubber scenario. Additionally, the existing line transitioned from

use of primarily natural gas for fuel to a combination of natural gas and coal. The existing line will continue to operate on these two fuels in the future as well. The post scrubber emissions are detailed in the input calculations provided in Attachment B. For purposes of visibility modeling, the proposed 24- hour emission limits were used as the modeled emission rates. Additional modeling, presented in Attachment C, examined impacts using the emission factor for the fuel with the highest NOx contribution (natural gas) for modeling maximum potential impacts and a combined fuel (natural gas and coal)

Page 4emission factor was used for modeling impacts at the permitted emission rate. Additional details of these emission factors are provided in Section 2.3 and Attachment B.
New Source Facility Emissions The emissions for the new indurating furnace are based, for most averaging times, on expected permit limits based on the BACT determinations for 80 2 , PM 10 , and PM2.5. 

### NOx emissions are based on the proposed 24-hour combined furnace limit. Biomass emissions for the expansion project were calculated by applying stack test data from the Minntac facility and scaling it to the Keetac project. Data from Minntac is used because biomass is not currently used in the existing furnace at Keetac nor is biomass used in any other taconite furnaces. The new Keetac furnace will use a combination of biomass and natural gas. The Minntac emission factors used are from a correlation developed by the MPCA from a series of stack tests at Minntac. The Minntac results were adjusted and applied to Keetac in accordance with a MPCA data evaluation which considers type of pellet (flux vs. acid) and mix offuels (natural gas
vs. biomass ratio). The new source emissions are summarized by emission groups and shown in Attachment B.
Modified Facility Emissions Keetac proposes to permit the stationary source 

### NOx emissions for the expansion project as a minor modification by netting emissions with the existing line. To create a credible emission reduction to offset the emission increase from the expansion, Keetac will be required to take a federally enforceable permit limit on both the new and the existing furnaces to remain below major modification thresholds. The proposed 24-hour emission limits for 

### NOx on the combined existing and expansion units is used to define potential 

### NOx emission rates for the future scenarios for modeling maximum daily impacts, as well as providing a conservative method for modeling annual average impacts. The modified facility emissions
are shown in Attachment B.

A change has been made to the emission factors detailed in the Class I modeling protocol for mobile

sources. Mobile source emissions (diesel trucks) were estimated in the protocol using conservative AP-42 emission factors. The AP-42 emission factors were published in 1996 and do not take into consideration new emission standards for off-road diesel engines. Keetac has reviewed non-road diesel emission regulations and believes that the pending standards associated with non-road diesels are more representative of emission from new trucks that will be purchased as part of the expansion project. Keetac plans to purchase new haul trucks, shovels, and dozers for the expansion. The old AP-42 emission factors were used to estimate emissions fi·om the existing non-road equipment and the new Tier 4

Page 5emission standards were used to estimate emissions for the new non-road equipment. Additional details regarding these calculations are presented in Attachment D. 

## 2.3 Emission Rate Calculation Basis
This section discusses how emissions rates that are inputs to the Class I modeling were calculated for both the existing and expansion emission units. It also describes how emission rates were calculated for the existing facility before the wet scrubber was installed on the existing indurating line. Some small rounding discrepancies may appear if you hand calculate the emissions rates using the emission factors and throughputs provided in the following sections and compare them to the values in the Attachment. The provided emission rates are based on the values calculated in the emission inventory included as pmt of the Permit Application submitted in October 2009, with some revisions per subsequent reviewer comments, updated emission factors and BACT limits. The emission inventory serves as the primary basis for the modeling emission inputs. The actual calculations of emission rates are described later in this section.


### 2.3.1 Proposed Project Modeled Emission Rates
A wide range of fuel mixes can be used in both the existing and new indurating lines. U.S. Steel has proposed fueling the new line with biomass, natural gas, coal, and fuel oil. The existing line is currently permitted to burn natural gas, fuel oil and coal. The mix of fuels used at any one time can vmy from zero to 100 percent. In comparing the emission rate of fuel mixes, firing both the existing and expansion lines

on 100 percent natural gas was determined to be the worst-case emissions scenario for the Class I modeling assessment. This scenario represents the maximum NOx emissions, which was determined through modeling to be the dominant visibility impacting pollutant. Maximum S02 emissions occur when burning 100 percent coal. However the difference in S0 2 emissions between 100 percent natural gas and 100 percent coal is not significant because a majority of the S0 2 comes from sulfur in the ore which is liberated from the ore and convetted to S0 2 in the indurating process. The modeled S02 emission rate for the existing furnace is based on an emission factor derived by the MPCA based on CEMs data and provided via email dated May 6, 201 0.

Class I modeling previously conducted for 100 percent natural gas on both the existing and new indurating lines indicated visibility impacts above FLM guidance (Attachment C). In addition, the frequency and duration at which both lines would be operating on 100 percent gas are limited. Therefore,

a combined NOx emission rate for the indurating furnaces was developed and modeled corresponding to
more realistic fuel mixes. Because this is a combined emission rate and the emissions could vary between

Page 6the new and existing furnace, an analysis was conducted to determine how to distribute the emissions between the two lines in order to model maximum impacts. For application of the proposed 24-hr 

### NOx emission limit, a sensitivity analysis was performed with respect to the distribution between existing and expansion kilns. In this sensitivity analysis emissions were modeled with all emissions coming from the existing line only in one run, the expansion line only in another run, and for an even distribution between the lines. Results indicated that the existing line's dispersion characteristics results in higher Class I impacts than the new lines dispersion characteristics. Therefore, for modeling purposes the existing line's emission rate was maximized and then the remaining 

### NOx emissions from the combined total were distributed to the new line. This distribution of emissions was used to represent the worst-case impact given the proposed 

### NOx emission limit.
Details of the emission factors and associated rates are provided in the following for the applicable emission unit types. These rates were used as the basis for calculating emissions used as inputs for the Class I modeling

2.3.1.1 Facility Expansion 

### i. New Indurating Line The following four emission points are associated with the new indurating line. Figure 2-1 shows their relationship to the process flow. Combustion emissions only exit the DDDI stack while the other stack emissions are primarily particulates. Some ore related S0 2 is emitted from the TPH stack.

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### NOx: Emission Factor Natural Gas (EF 11 g): 1.726 lb/ston pellets produced Emission Factor Biomass (EFbio): 0.854lb/ston pellets produced Emission Factor Coal (EFcoal): 0.639lb/ston pellets produced Emission Factor Fuel Oil (EFfo): 0.992lb/ston pellets produced Basis Natural Gas: Existing facility stack test, 10/15/05

Basis Biomass: MPCA guidance document sent to Minntac by Hongming Jiang in late 2004, exponential-decay fit formula for wood combustion combined with Minntac Line 7 stack test production data (5/21/04). Basis Coal: Existing facility stack test, 5/31/06 Basis Fuel Oil: Existing facility stack test, 7/25/00

Rated Capacity (RC): 450 tons pellet produced/hr Emission Rate Natural Gas (ERng) = EFng * RC = 776.8 lb/hr NOx (776.8 lb/hr * hr/3600 sec* 453.6 g/lb = 97.9 g/s) (Note: Facility is proposing a combined NOx limit of 1652lb/hr; see Section ii, Process Improvement Energy Efficiency Factor for more details.)

Emission Rate Biomass (ERbio) 

### = EFbio * RC 

### = 384.5 lb/hr NOx Emission Rate Coal (ERcoal) 

### = EFcoal * RC 

### = 287.4lb/hr NOx Emission Rate Fuel Oil (ERfo) 

### = EFfo * RC 

### = 446.3 lb/hr NOx

Natural gas is the worst case fuel for NOx emissions. The 10/15/05 natural gas stack test emission factor for the existing kiln is used with the rated capacity ofDDD1 to calculate the NOx emission rate.

Page 9

### PM to: EF: 0.012 gr/dscf (3-hour averaging time) Basis: BACT limit RC: 203,967 dscfm
ER = EF * lb/7000 gr * 60 min/hr * RC = 21.0 lb/hr PM 10 (21.0 lb/hr * hr/3600 sec* 453.6 glib= 2.64 g/s)
The BACT limit is used with the rated capacity ofDDD1 to calculate a PM 10 emission rate. The BACT limit will be used for all fuels.


### 802: EF: 8 ppmv 

### S0 2 as measured on a wet basis on a 24 hour average at the 19.1 lb 

### 80 2 /hr limit for DDD1
Basis: The DDDI process design, control equipment performance guarantee.
RC: 203,967 dscfm DDDlER = EF * 60 min/hr * lb mol/385.3 ft3 * 64 lbllb mole* RC =

= 19.1 lb 

### 80 2 /hr 24-hour average basis (19 .1 lb/hr * hr/3600 sec * 453.6 g/lb = 2.407 g/s)

A total emission rate for DDD I of 19.1 lb SOz/hr is based on a control performance of 8 ppmv 

### 80 2 as measured on a wet basis at the rated flow capacity for DDDI. The 8 ppmv control basis is used because it reflects worst case expected performance during an optimization period. The 24-hr block emission rate is used for visibility modeling since the criteria are based on 24-hr block modeling.
The 23.3 lb 

### 80 2 /hr emission rate on a 3-hour average basis is based on the vendor guaranteed control modified to the shmter averaging period. The control equipment exhaust 

### 80 2 concentration at DDD 1 of 5 ppm wet was corrected to 6ppm dry on a 15% 

### 0 2 wet basis and applied at the rated capacity listed above and the 3-hour average upper control limit (UCL, 1.9) of 

### 80 2 CEMS data from the Minntac plant. The initial vendor guarantee of9.7lb/hr was 5 ppm wet at an average flowrate of 160,629 dscfm. The initial vendor guarantee was corrected for flowrate (203,967 dscfm) and the UCL. ER =Vendor Limit* Flow Correction* UCL ratio= 23.3 lb/hr 

### 80 2

Page 10=23.3 lb/hr S0 2 3-hour average basis (DDD1 only) (23.3 lb/hr * hr/3600 sec * 453.6 glib= 2.94 g/s)
The 3-hr emission rate of23.3 lb S0 2 /hr was used to demonstrate that the modeled impact ofthe project is below the S0 2 SIL concentration (3-hour averaging time). The 24-hour modeling rates were used for all other modeling outputs, including acid deposition.

SAM: EF Natural Gas: Uncontrolled SAM emissions of0.030 lb SAM/s-ton pellets produced. Basis: SAM stack test while firing natural gas (Minntac, l/13/04). This result gets split between DDDI and TPH by Metso modeling estimates of approximately 64% S0 2 DDD1 to 36% S0 2 TPH when firing 100% natural gas as fuel. A control efficiency of95% for the CFB was used. RC: 450 tons pellet produced/hr
EF: 0.030 lb SAM/s-ton pellets- uncontrolled %SAMtoDDD1: 64% SAM Control Efficiency: 95%
ER = RC *EF *%SAM to DDDl/100% * (0.05) = 0.432lb/hr SAM (0.432 lb/hr * hr/3600 sec* 453.6 g/lb = 0.05 g/s)

A SAM emission rate based on natural gas firing is consistent with the worst case fuel scenario for total visibility impacts.
2. TPH 

### NOx: No combustion products anticipated for TPH

EF: 0.012 gr/dscf(3-hour averaging time)
Basis: BACT limit
RC: 110,213 dscfm

Page 11ER 

### = EF * 60 min/hr * lb/7000 gr * RC 

### = 11.3 lb/hr PM 10 (11.3 lb/hr * hr/3600 sec * 453.6 g/lb 

## = 1.43 g/s)
The BACT limit is used with the rated capacity ofTPH to calculate a PM 10 emission rate. The BACT limit will be used for all fuels.


### 802: EF: 5 ppmv S0 2 as measured on a wet basis at the 6.4 lb 80 2 /hr for TPH (3-hour and 24- hour averaging time)
Basis: The TPH process design, control equipment performance guarantee.
RC: 128,904 scfm (68° F)

ER 

### = EF * 60 min/hr * 385.3 lb mol/ft3 * 64lb/lb mole* RC 

### =

= 6.4lb/hr S0 2 (TPH only)
The 6.3 lb S0 2 /hr emission rate is the estimated controlled S0 2 emission rate and was used in the air quality modeling analysis initially used to demonstrate compliance with NAAQS. The calculated S0 2 emission rate based on the control equipment guarantee of 5 ppmv S0 2
as measured on a wet basis at the rated flow capacity above is 6.4 lb SOz/hr. Given the slight difference in these values, an emission rate of 6.3 lb S0 2 /hr was retained to maintain consistency with the original air quality modeling analysis. (6.3 lb/hr * hr/3600 sec* 453.6 g/lb 

## = 0.79 g/s)

SAM: EF Natural Gas: Uncontrolled SAM emissions of0.030 lb SAM/s-ton pellets produced (3 hour averaging time). Basis: Natural gas SAM stack test (Minntac, 1/13/04). This result gets split between DDDI and TPH by Metso modeling estimates of approximately 64% S0 2 DDDl to 36% S0 2 TPH when firing I 00% natural gas as fuel. A control efficiency of 95 % for the CFB
was used. RC: 450 tons pellet produced/hr EF: 0.030 lb SAM/s-ton pellets- uncontrolled %SAM to DDDI: 36%
Page 12ER = RC *EF *%SAM to DDD1/100% * (0.05) = 0.243 lb/hr SAM (0.24 lb/hr * hr/3600 sec * 453.6 glib= 0.03 g/s)
3. DDD2 No combustion products or S0 2 are expected to be emitted from DDD2.

EF: 0.012 gr/dscf (3-hour averaging time)
Basis: BACT limit
RC: 138,495 dscfm

ER = EF *lb/7000 gr * 60 min/hr * RC = 14.2 lb/hr PM 10 (14.2 lb/hr * hr/3600 sec* 453.6 glib= 1.79 gls)
The BACT limit is used with the rated capacity ofDDD2 to calculate a PM 10 emission rate.
4. C4 Cooler No combustion products or S0 2 are expected to be emitted from C4 Cooler.

PMw:
EF: 0.012 gr/dscf (3-hour averaging time)
Basis: BACT Limit
RC: 191,624 dscfm

ER = EF * lb/7000 gr * 60 min/hr * RC = 19.7lb/hr PM 10 (19.7lb/hr * hr/3600 sec* 453.6 glib= 2.48 gls)
The BACT limit is used with the rated capacity of C4 to calculate a PM 10 emission rate.
ii. Process Improvement Energy Efficiency Factor NOx emissions are generally related to fuel combustion and therefore improvements in heat recovery design can reduce the generation ofNOx emissions by reducing fuel consumption.

Page 13The new taconite indurating furnace is designed to use approximately 36% to 44% less fuel than the existing furnace, on an MMbtu per short ton of pellet produced basis. NOx emission rates used in the emission inventory were based on emission rates from the existing furnace and
were used as model inputs in the previous modeling for both the existing line and new line and therefore previous modeling did not account for reductions associated with energy efficiency in the new line. The factors for the existing furnace have been reviewed and agreed to by the MPCA. The NOx emission rates are based on testing results from the existing furnace which has a lower heat recovery and a higher fuel use rate than expected for the new furnace. The reduced fuel usage numbers were developed using process design inputs from Hatch. These improvements are accomplished by:

• Expanding the preheat and cooling sections of the furnace to increase the available pellet smface for heat transfer

• Improved air flow patterns for more efficient transfer of heat

• Optimizing use of recovered energy between heating unfired pellets and combustion air

• Improved air seals to minimize infiltration of cold air into the furnace

• Improved insulation to minimize heat loss
The exact relationship between reduced fuel usage and the resulting reduction in NOx emissions is not known. Due to the uncertainty associated with the exact reduction in NOx emissions that will be achieved, no change was made to the emission rates that were used for the original model inputs.
NOx generation is maximized when the existing line and the new line are running 100% natural gas. The range of fueling scenarios was evaluated to understand and define ranges reflective of operating conditions for the kilns.

NOx emissions were calculated by multiplying fuel specific emission factors by the fuel mix used and the process throughput to get a totallb/hr rate.
Fuel specific emission factor (lbs/ton pellet) x max pellet through put (tons/In·)= lbs/hr NOx

Page 14Max hourly rates: Expansion kiln- 450tph, Existing kiln- 830 tph
Total annual production rates do not equate directly to instantaneous hourly max rates because it is not feasible to run the line continuously thought out the entire year.
The expansion kiln emission factor was modified by assuming a conservative 20% reduction in NOx emissions due to the heat recovery design of the new furnace. These calculations show that an emission rate of 1,652 Ib/hr is an approximate bound on where both kilns can run at the same time while one is firing 100% natural gas.
The 1,652 lb/hr rate was deteJmined primarily by evaluating kiln fueling scenarios by using this estimate of improved efficiency for the expansion kiln (applied to the existing emission factor with a 20% decrease).
U. S. Steel is proposing to have a NOx emission limit of 1652 lb/hr for the combination of emissions from the existing line and new line. This was derived from the evaluation of fueling scenarios for both operating lines. The fueling scenarios range from 100% natural gas for both kilns to 0% natural gas/1 00% solid fuel for both kilns. Originally, the calculated NOx emission rate was approximately 1660 lb/hr under a fueling scenario of 100% natural gas on the existing line and I 00% solid fuel on the expansion line. Since this number was calculated, small changes have been made to the S0 2 emission rates. To keep the proposed number of affected days near the original proposal, the NOx emission rate was reduced slightly to 1652 lbs/hr. The target operating scenario (60% solid fuel existing/50% solid fuel expansion) has a projected emission rate below the 1652 limit. When the existing line is operating at its target fueling rate of 60% solid fuels and 40% natural gas, the expansion line is capable offueling at 100% natural gas and operates below the 1652 lb/Iu· limit.
(1652 lblhr * hr/3600 sec* 453.6 g/lb = 208.2 g/s) (DDD 1 Contribution=Total Limit- Existing Kiln Limit= 208.2-180.5=27. 7 g/s)
Total Indurating Furnace NOx Emissions =New Indurating Furnace+ Existing Indurating Furnace

Page 15New Indurating Furnace Emissions= (% Fuel*EFng+% Fuel*EFbio+% Fuel*EFcoal+ % Fuei*EFfo) *Pellet Tput *(1-eng efffactor) Existing Indurating Furnace Emissions= (%Fuel *EFng+% Fuei*EFcoal) * Pellet Tput
iii. Baghouses 

### PMIO: Emission Factor: 0.002 gr/dscf (3-hour averaging time)
Basis: PM 10 BACT limit
Rated Capacity: Varies (see Attachment B)

ER = EF * 60 min/hr * lb/7000 gr * RC =Varies (see Attachment B)
The BACT limit is used with the rated capacity of the individual baghouses to calculate a PM 10 emission rate.
iv. Mobile Sources, New Large Diesels 

### NOx: EF: 2.6 g/(hp-hr) (0.82 lb/mmbtu)
Basis: Diesel Engine, Tier 4 Standard required in 2011
RC: 72 mmbtu/hr, total proposed new engines

ER = EF * RC = 59 lb/hr NOx (59 lb/hr * hr/3600 sec* 453.6 glib= 7.4 g/s)
The Tier 4 Standard is used with the rated capacity of the proposed new diesel engines to calculate a NOx emission rate. Applicable Keetac equipment includes 13 new trucks, 4 new shovels, and 1 new loader.



### PM 10 : EF: 1.94E-02 lb/mmbtu
Basis: Diesel Engine, Tier 4 Standard required in 2011, PM 0.075 g/(hp-hr), convetted to PM 10 by AP-42 ratio. AP-42, 5th Edition, Section 3.4, 10/96, (PM 10 /PM=0.0573/0.0697)

Page 16RC: 72 mmbtu/hr, total proposed new engines
ER = EF * RC = 1.4 lb/hr 

### PMw (1.4lb/hr * hr/3600 sec* 453.6 g/lb = 0.18 g/s)
The Tier 4 Standard is used with the rated capacity of the proposed new diesel engines to calculate an emission rate.
S02: EF: 1.52E-03 lb/mmbtu
Basis: Diesel Engine, Tier 4 Standard required in 2011, 15 ppm, and AP-42, 5th Edition, Section 3.4, 10/96
RC: 72 mmbtu/hr, total proposed new engines
ER= EF * RC = 0.1lb/hr S02 (O.llb/hr * hr/3600 sec* 453.6 g/lb = 0.01 g/s)
The Tier 4 Standard is used with the rated capacity of the proposed new diesel engines to calculate a so2 emission rate.

Page 17v. Mobile Sources, New Small Diesels 

### NOx: EF: 0.3 g/(hp-hr) (0.0945 lb/mmbtu)
Basis: Diesel Engine, Tier 4 Standard
RC: 4 mmbtu/hr, total proposed new engines

ER = EF * RC = 0.4 lb/hr 

### NOx (0.4lb/hr * hr/3600 sec* 453.6 glib= 0.05 g/s)
The Tier 4 Standard is used with the rated capacity of the proposed new diesel engines to calculate a 

### NOx emission rate. Applicable Keetac equipment includes 4 new dozers and 

### 1 new grader.

PM 

### to: EF: 3.15E-03 lb/mmbtu
Basis: Diesel Engine, Tier 4 Standard required in 2011, PM 0.01 g/(hp-hr), all PM assumed to equal 

### PMw
RC: 4 mmbtu/hr, total proposed new engines

ER = EF * RC = 0.013 lb/hr PM10 (0.013 lb/hr * hr/3600 sec* 453.6 g/lb = 0.0016 g/s)
The Tier 4 Standard is used with the rated capacity of the proposed new diesel engines to calculate a PM 10 emission rate.
S02: EF: 1.52E-03 lb/mmbtu
Basis: Diesel Engine, Tier 4 Standard required in 2011, 15 ppm, and AP-42, 5th Edition, Section 3 .4, I 0/96
RC: 4 mmbtu/hr, total proposed new engines

Page 18

### 2.3.1.2 ER = EF * RC = 0.01lb/hr 

### SOz (0.01lb/hr * hr/3600 sec* 453.6 g/lb = 0.001 g/s)
The Tier 4 Standard is used with the rated capacity of the proposed new diesel engines to calculate a S0 2 emission rate. Keetac proposes 4 new dozers and 1 new grader. The emission calculations are summarized in spreadsheet EICurrent.

Existing Facility Emission factors and associated rates are provided in the following for the applicable emission unit types. These rates were used as the basis for calculating emissions used as inputs for the Class I modeling


### i. Induration NOx: EF Natural Gas: 1.726lb/ston pellet produced
Basis: Average stack test result from 1 0/15/05

EF Coal: 0.639 lb/ston pellet produced
Basis: Average stack test result from 5/31/06

EF Oil: 0.9918 lb/ston pellet produced
Basis: Average stack test result from 7/25/00
RC: 830 tons pellet produced/hr

ER Natural Gas= EF * RC = 1433 lb/hr NOx (1433 lb/hr * hr/3600 sec* 453.6 g/lb = 180.5 g/s)

ER Coal = EF * RC = 530 lb/hr NOx

ER Oil = EF * RC = 823 lb/hr NOx
The most current natural gas stack test emission factor for the existing kiln is used with the rated capacity to calculate a NOx emission rate.

Page 19PM to: EF Natural Gas: 0.019 gr/dscf(3-hour averaging time)
Basis: MACT PM limit (0.0 1 gr/dscf) 

# * 1.86 (PM 10 /PM stack test ratio, 1 0/19/05).

EF Coal: 0.014 gr/dscf
Basis: MACT PM limit (0.0 1 gr/dscf) 

# * 1.38 (PM 10 /PM stack test ratio, 5/31/06).

EF Oil: 0.019 gr/dscf(3-hour averaging time)
Basis: MACT PM limit (0.01 gr/dscf) 

## * 1.86 (PM 10 /PM stack test ratio, 10/19/05).
RC: 576,000 dscfm

ER Natural Gas= EF 

## * lb/7000 gr 

## * 60 minlhr 

## * RC = 91.9 lb/hr PM 10 (91.9 lb/hr 

# * hr/3600 sec 

# * 453.6 glib = 11.6 g/s)

ER Coal= EF 

## * lb/7000 gr 

## * 60 min/hr 

## * RC = 68.1 lb/hr PM 10
ER Oil= EF 

## * lb/7000 gr 

## * 60 min/hr 

## * RC = 91.9lb/hr PM 10
The MACT limit is combined with stack test results to estimate a PM 10 emission factor. That emission factor is used with the rated capacity of the kiln to calculate a PM 10 emission rate. The natural gas emission factor which is the highest was used in all modeling runs.


### S02: EF Natural Gas: 0.282lb/ston pellet produced (3-hour averaging time)
Basis: Natural gas stack test, 10/19/2005

EF Coal: 0.296 lb/ston pellet produced
Basis: MPCA email, 5/06/2010

EF Oil: 0.1154 lb/ston pellet produced
Basis: Oil stack test, 7/25/2000
RC: 830 tons pellet produced/lu·
Page 20ER Natural Gas= EF * RC = 233.7lb/hr S0 2 (233.7lb/hr * hr/3600 sec* 453.6 g/lb = 29.4 g/s)

ER Coal= EF * RC = 243.2lblhr S0 2 (243.2 lb/hr * hr/3600 sec* 453.6 g/lb = 30.6 g/s)

ER Oil = EF * RC = 95.8 lb/hr S0 2
The stack test data was used with the rated capacity to calculate a S0 2 emission rate. Coal is expected to be the worst case fuel for S0 2 emissions. For prior submittals, the natural gas test showed a higher outlet emission rate and was therefore used for the modeled emissions rate for all modeling runs. Subsequent comment by MPCA has yielded higher outlet emission rates based on coal fueling. This higher rate is therefore used for the modeled emission rate for the updated nms in this report.
SAM:

Emission Factor: Ratio of SAM to S0 2 of 0.120 lb SAM/lb S0 2 emitted Basis: SAM stack test while firing natural gas (Minntac,l/13/04). S0 2 ER: 243.2 Ib/hr so2
EF: 0.120 lb SAM/lb S02
ER = S0 2 ER *EF = 29.2lb/hr SAM (29.2lb/hr * hr/3600 sec* 453.6 glib= 3.7 g/s)
The stack test ratio was used with the S0 2 rate to calculate a SAM emission rate. The highest S0 2 outlet emission rate is therefore used for the modeled SAM emission rate for all modeling runs.


### ii. Pellet Cooler

No combustion products or S0 2 are expected to be emitted from the pellet cooler

Page 21

### PM to: EF: 10.1 lb/hr (3-hour averaging time)
Basis: Title V permit limit ( 49 lb/hr) times 0.205 (PM 10 /PM ratio from United Taconite stack test results, 6/15/04 and 4/17/0 I).
RC: 8760 hours

ER = EF * RC = 10.1 lb/hr PM 10 (IO.llb/hr * hr/3600 sec* 453.6 g/lb = 1.27 g/s)
The Title V PM limit is used with the PM 10 /PM ratio from a similar emission unit to calculate
a PM 10 emission rate.
iii. 

### Material Handling/Scrubbers PM 

### to: EF: 0.008 gr/dscf (3-hour averaging time)
Basis: PM/PM 10 MACT limit
RC: Varies (see Attachment B)

ER = EF * 60 min/hr * lb/7000 gr * RC =Varies (see Attachment B)
The MACT limit is used with the rated capacity of the individual baghouses to calculate a PM 10 emission rate.


### iv. Mobile Sources, Existing Large Diesels NOx: EF: 3.2lb/mmbtu
Basis: AP-42, 5th Edition, Section 3.4, 10/96
RC: 95 mmbtu/hr, total existing engines

ER = EF * RC = 304 lb/hr 

### NOx (304lb/hr * hr/3600 sec* 453.6 g/lb = 38.3 g/s)

Page 22AP-42 emission factor is used with the rated capacity of the existing diesel engines to calculate a conservative 

### NOx emission rate. Applicable Keetac mobiles include 16 trucks, 6 shovels, and I loader.

PM 

### to: EF: 0.0573 lb/mmbtu
Basis: AP-42, 5th Edition, Section 3.4, 10/96
RC: 95 mmbtu/hr, total existing engines
E R = EF * RC = 5.44lb/hr PM 10 (5.44lb/hr * hr/3600 sec* 453.6 g/lb 

## = 0.69 g/s)
AP-42 emission factor is used with the rated capacity of the existing diesel engines to calculate a PM 10 emission rate.


### S02: EF: 5.05E-02 lb/mmbtu
Basis: AP-42, 5th Edition, Section 3.4, 10/96
RC: 95 mmbtu/hr, total existing engines
ER = EF * RC = 4.8 lb/hr S02 (4.8 lb/hr * hr/3600 sec* 453.6 g/lb = 0.6 g/s)
AP-42 emission factor is used with the rated capacity of the existing diesel engines to calculate a conservative S0 2 emission rate.

v. Mobile Sources, Existing Small Diesel 

### NOx: EF: 4.41 lb/mmbtu
Basis: AP42, 5th Edition, Section 3.3, 10/96
RC: 7.8 mmbtu/hr, total proposed new engines
E R 

## = EF * RC 

## = 34 lb/hr 

### NOx (34 lb/hr * hr/3600 sec* 453.6 g/lb 

## = 4.3 g/s)

Page 23

### 2.3.2

2.3.2.1 AP-42 emission factor is used with the rated capacity of the existing diesel engines to calculate a 

### NOx emission rate. Keetac currently has 7 dozers and 3 graders.


### PM1o: EF: 0.31 lb/mmbtu
Basis: AP42, 5th Edition, Section 3.3, 10/96
RC: 7.8 mmbtu/hr, total proposed new engines
ER 

### = EF * RC 

### = 2.4lb/hr PM 10 (2.4 lb/hr * hr/3600 sec* 453.6 g/lb = 0.30 g/s)
AP-42 emission factor is used with the rated capacity of the existing diesel engines to calculate a PM 10 emission rate.


### S02: EF: 0.0505- lb/mmbtu
Basis: AP42, 5th Edition, Section 3.3, 10/96

RC: 7.8 mmbtu/hr, total proposed new engines

ER = EF * RC = 0.4 lb/hr S0 2 (0.4lb/hr * hr/3600 sec * 453.6 g/lb = 0.05 g/s)

AP-42 emission factor is used with the rated capacity of the existing diesel engines to calculate a conservative S0 2 emission rate.


### Pre-Scrubber Facility
Existing Facility 

### i. Induration Induration rates and parameters for the Pre-scrubber facility are based on stack tests performed in 2000. The emission factor used for 

### NOx was 1.906 lb/ston and for S0 2 was 0.222 lb/ston. These factors are from a 7/25/2000 stack test as revised by Hongming Jiang of the MPCA. At the time, the facility was

Page 24exclusively fired on Natural Gas. The induration exhaust was split between the two stacks, SV30 and SV31.
ii. Baghouses Baghouses and other non-combustion sources were modeled utilizing the same methods as described above in section l.b.ii, with limited exceptions. The exceptions include: 1) Stacks related to the coal handling system are not included in the PreScrubber scenario (SV53,54,57) because they were not installed at that time 2) Existing stacks with projected increased emissions are modeled at their original, pre-project emissions. For example, the product loadout (SV65) emission rate will increase with the increased pellet production, however, the previous production rates were used for the pre-scrubber facility.

111. Mobile Sources Mobile Sources at the mine include Haul Trucks, Loaders, Bulldozers, Shovels, and Graders. Emissions are calculated similar to section 1. b.iii., with one exception. For the Pre-project scenario, S0 2 emission factors were used to correlate to 5% Sulfur diesel. As noted in the expansion mobile diesel discussion, the proposed project will utilize 0.15% Sulfur diesel.

Page 25Table 2. Scenario 1 -Existing Line- Baseline/Pre Scrubber

NG NG 24-hr. Max (lbs/hr) Annual Avg. (lbs/hr) PM10 

## so2 NOx PM10 S02 NOx Comments Existing Detailed Emission Induration 191.53 183.99 1582.08 160.46 154.14 1325.43 Factors in Appendix E New Induration 

### NA NA NA NA NA NA Other PM sources modeled Stationary 50.0 0.0 0.0 50.0 0.0 0.0 at PTE

Existing Mobiles 5.2 4.6 230.5 4.5 4.1 203.7 Data from 2007 rates New Mobiles 

### NA NA NA NA NA NA TOTAL

(lb/hr) 246.7 188.6 1812.6 215.0 158.2 1529.1 TOTAL (tons/yr) 1081 826 7939 942 693 6697Table 3. Scenario 2
- Existing Line- Post Scrubber Post Scrubber NG Coal NG&Coal
24-hr. Max (lbs/hr) 24-hr. Max (lbs/hr) Annual Avg. (lbs/hr) Comments
PM10 SOz NOx PM10 SOz NOx PM10 502 NOx Existing Detailed Emission Induration 75.6 233.7 1432.9 82.1 212.5 530.0 63.2 176.2 723.2 Factors in Appendix E New Induration NA NA NA NA NA NA NA NA NA Other All PM sources Stationary 50.0 0.0 0.0 50.0 0.0 0.0 50.0 0.0 0.0 modeled at PTE Existing Mobiles 5.2 4.6 230.5 5.2 4.6 230.5 4.5 4.1 203.7 Data from 2007 rates New Mobiles NA NA NA NA NA NA NA NA NA TOTAL

(lb/hr) 130.7 238.3 1663.4 137.3 217.2 760.5 117.7 180.3 926.9 TOTAL (tons/yr) 573 1044 7286 601 951 3331 516 790 4060KeewatinTaconiteKeewatin,MinnesotaEmissionRateCalculationsforClassIModeling-KilnScenarioElBASELINEUnitPollutantTimeframeEU030.lndurator.PhaseIINOxNov99toOct01NOx24HRMaximumS02Nov99toOct0150224HRMaximumPM10Nov99toOct01PM1024HRMaximumPM2.5,FilterableOnlyNov99toOct01PM2.5,FilterableOnly24HRMaximumPM2.5,TotalNov99toOct01PM2.5.Total24HRMaximum[1]RevisedemissionfactorsperMPCA.HongmingJiang.Originaldataused1.9841b/s.ton[2]RevisedemissionfactorsperMPCA.HongmingJiang,Originaldataused0.2308Ibis.ton[3]RevisedemissionfactorsperMPCA,HongmingJiang,Originaldataused0.341lb/s.tonThroughput1037867083010378670830103786708301037867083010378670830EmissionFactorUnits(lb/unit)UnitBasiss.tonpellets/yr1.906s.ton7/25/00StackTest[1]s.tonpellets/hr1.906s.ton7/25/00StackTest[1]s.tonpellets/yr0.222s.ton7/25/00StackTest[2]s.tonpellets/hr0.222s.ton7/25/00StackTest[2]s.tonpellets/yr0.231s.ton7/25/00StackTest[3]s.tonpellets/hr0.231s.ton7/25/00StackTest[3]s.tonpellets/yr0.073s.ton9/24/08StackTest[4]s.tonpellets/hr0.073s.ton9/24/08StackTest[4]s.tonpellets/yr0.098s.ton9/24/08StackTest[4]s.tonpellets/hr0.098s.ton9/24/08StackTest[4][4]PreliminaryPM10andPM2.5datafrom9/24/2008stacktestusedtoratioPM2.5 emissionfactorsfromtheoriginalPM10stacktestdata(7/25/2000)AppendixEClassIEmissionCalculationsPSDBaselineIEmissionAdditionEmissionsRateEmissionsUnits(ton/yr)(s.ton/yr)(g/s)9891.47s.ton/yr359926285.561582.08lb/hrNA199.341150.35s.ton/yrNA33.09183.99lb/hrNA23.181197.51s.ton/yrNA34.45191.53lb/hrNA24.13377.32s.ton/yrNA10.8560.35lb/hrNA7.60510.51s.ton/yrNA14.6981.65lb/hrNA10.29POSTSCRUBBERUnitPollutantTimeframeThroughputUnitsEU030.lndurator.PhaseIINOx,Nat.GasAverage2006/20072427954s.tonpellets/yrNOx,CoalAverage2006/20073357352s.tonpellets/yrTotal,NOxAverage2006/2007NOx,Nat.Gas24HRMaximum830s.tonpellets/hrNOx,Coal24HRMaximum830s.tonpellets/hrS02,Nat.GasAver'!ge2006/20072427954s.tonpellets/yrS02,CoalAverage2006/20073357352s.tonpellets/yrTotal,S02Average2006/2007S02,Nat.Gas24HRMaximum830s.tonpellets/hrS02,Coal24HRMaximum830s.tonpellets/hrPM10,Nat.GasAverage2006/20072427954s.tonpellets/yrPM10,CoalAverage2006/20073357352s.tonpellets/yrTotal,PM10Average2006/2007PM10,Nat.Gas24HRMaximum830s.tonpellets/hrPM10,Coal24HRMaximum830s.tonpellets/hrPM2.5,FilterableOnly,Nat.GasAverage2006/20072427954s.tonpellets/yrPM2.5,FilterableOnly,CoalAverage2006/20073357352s.tonpellets/yrTotal,PM2.5,FilterableOnlyAverage2006/2007PM2.5,FilterableOnly,Nat.Gas24HRMaximum830s.tonpellets/hrPM2.5,FilterableOnly,Coal24HRMaximum830s.tonpellets/hrPM2.5,Total,Nat.GasAverage2006/20072427954s.tonpellets/yrPM2.5,Total,CoalAverage2006/20073357352s.tonpellets/yrTotal,PM2.5,TotalAverage2006/2007PM2.5,Total,Nat.Gas24HRMaximum830s.tonpellets/hrPM2.5,Total,Coal24HRMaximum830s.tonpellets/hr[1]10/19/2005stacktestPM10fractionusedwith9/24/08stacktestdatatoratiotoaPM2.5emissionfactor[1]5/31/2006stacktestPM10fractionusedwith9/24/08stacktestdatatoratiotoaPM2.5emissionfactor[3]PreliminaryPM10andPM2.5datafrom9/24/2008stacktest,Assumed80%controlEmissionFactor(lb/unit)Unit1.726s.ton0.639s.ton1.726s.ton0.639s.ton0.282s.ton0.256s.ton0.282s.ton0.256s.ton0.091s.ton0.099s.ton0.091s.ton0.099s.ton0.020s.ton0.022s.ton0.020s.ton0.022s.ton0.185s.ton0.185s.ton0.185s.ton0.185s.tonModelingPSDBaselineEmissionAdditionEmissionsRateBasisEmissionsUnits(ton/yr)(s.ton/yr)(g/s)10/19/2005StackTest2095.71s.ton/yrNA60.295/31/2006StackTest1071.94s.ton/yrNA30.843167.6591.1210/19/2005StackTest1432.84lb/hrNA180.545/31/2006StackTest530.01lb/hrNA66.7810/19/2005StackTest341.75s.ton/yrNA9.835/31/2006StackTest429.85s.ton/yrNA12.37771.6122.2010/19/2005StackTest233.66lb/hrNA29.445/31/2006StackTest212.54lb/hrNA26.7810/19/2005StackTest110.54s.ton/yrNA3.185/31/2006StackTest166.20s.ton/yrNA4.78276.747.9610/19/2005StackTest75.57lb/hrNA9.525/31/2006StackTest82.18lb/hrNA10.3510/19/2005StackTest[124.54s.ton/yrNA0.715/31/2006StackTest[2]36.90s.ton/yrNA1.0661.441.7710/19/2005StackTest[116.78lb/hrNA2.115/31/2006StackTest[2]18.24lb/hrNA2.309/24/08StackTest[3]44.87s.ton/yrNA1.299/24/08StackTest[3]62.05s.ton/yrNA1.78106.923.089/24/08StackTest[3]30.68lb/hrNA3.879/24/08StackTest[3]30.68lb/hrNA3.87