Figure 4-4. Adjustable-throat venturi scrubber. '

4-9


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5-26


3.0 EMISSIONS FROM ELEMENTAL PHOSPHORUS PLANTS

The primary objectives of this study are to estimate current emission
rates of the radionuclides Po-210 and Pb-210 from elemental phosphorus
plants and to evaluate control measures for those emissions. This section
identifies potential sources of Po-210 and Pb-210 emissions, presents
estimates of emission levels, and provides information on the character-
istics of the emissions as a basis for the control technology assessments
that are presented in Sections 4 and 5. The discussion addresses the
different sources of radionuclide emissions within the elemental
phosphorus process, but it focuses on emissions from the calcining (or
nodulizing) operation because emissions from the calciner are much greater
than those from all other plant operations combined. The three sections
below provide a brief discussion of the different emission sources and the
estimated levels of emissions from these sources, discuss calciner
emissions in detail, and present estimates of baseline emissions for
calcining operations at the five operating facilities.

3.1 SOURCES OF RADIONUCLIDE EMISSIONS

The Po-210 and Pb-210 concentration data presented in Section 2.2.2
indicated that these radionuclides are present at significant levels in
three elemental phosphorus production streams--the ore feed, calcined
nodules, and slag from the electric furnaces. If the processing,
handling, or storage of these process streams generates particulate matter
(PM) emissions, then Po-210 and Pb-210 are emitted to the atmosphere. The
operations that result in emissions include high-temperature furnaces
(specifically the calciner and the electric furnaces); nodule cooling,
crushing, and screening; and transfer and storage of ore, nodules, slag,
electric furnace ESP catch, and calciner air pollution control device
(APCD) catch. The paragraphs below briefly describe each of these sources
and present preliminary estimates of the levels of Po-210 and Pb-210
emissions from these sources. Table 3-1 provides a summary of these
preliminary estimates for the different sources as a means of comparing
the relative levels of emissions from those sources. These estimates are
based on information collected by EPA surveys and sampling programs that
were conducted in support of the 1983 NESHAP proposal. ‘~* More detailed


+60/3-B4A-or0
EPA=#50/9-88-045

Characterization and Control
of Radionuclide Emissions
From Elemental
_ Phosphorus Production

Emissions Standards Division

U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
February 1989


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5-22


rewetted by water-only nozzles, or it may be injected wet or dry into a
fluidized bed with overhead water sprays. The ensuing discussion focuses
upon one of these systems--the atomizing spray dryer absorber--because it
is the most likely to be applied to metallurgical furnaces such as those
in elemental phosphorus plants.

Figure 4-8 illustrates a typical spray drying process. '° Lime is
slaked, mixed with water, and then pumped as a slurry to a feed tank.
Depending on the inlet concentration of pollutants, slurry is metered into
the spray absorber (shown with a rotary atomizer in Figure 4-8). Flue gas
heat is sufficient to dry the slurry into a solid powder within the
reactor vessel, and some of the solids are collected in the bottom of the
absorber vessel while the remainder are collected in the particle
collector. Recycle of solids back to the feed tank may be selected as an
option if sorbent utilization is very low or higher removals of gaseous
pollutants are desired.

The lime feed rate to the spray dryer affects acid gas removal
efficiencies; it also has a significant impact on cost. The control of HF
and S02 are governed by the following chemical reactions.

Ca(OH) 7+S0, + CaSO; * 1/2 H20+1/2 H20 (Eq. 4-3)
CaSO3 * 1/2 H,O+1/2 0.+3/2 H20 + CaSO, 2H20 (Eq. 4-4)
Ca(OH) ,+2HF + CaF, * 2 H20 ’ (Eq. 4-5)

Data collected from combustion processes indicate that acceptable levels
of acid gas control can be achieved at a 1.5:1 stoichiometric ratio of
lime to HF and SO. combined. At that stoichiometric ratio, the
requirements for lime addition are 1.7 kg lime per kg of SO, and 2.8 kg of
lime per kg of HF emitted from the kiln.

Temperatures should be maintained at levels that promote condensation
of volatile metals such as Po-210 and Pb-210 and, at the same time,
prevent liquid condensation. The control of this process to achieve
optimal temperatures is relatively simple. The spray dryer outlet flue
gas temperature and moisture are controlled to a narrow range. Sorbent is

4-18


When a corrosive environment such as that found in the nodulizing
kiln exhaust exists, stainless steel is recommended for ductwork and
filter housings. Even this material may be insufficient in highly
corrosive atmospheres, and epoxy- or vinyl-coated stainless steel or
fiber-reinforced plastics may be necessary.

In severe applications like those in elemental phosphorus plants, it
may be necessary to modify and improve the environment to which the system
will be exposed by pretreating the air prior to entry into the HEPA
system. Scrubbers may be employed upstream to remove corrosive
constituents such as inorganic acids. Consideration must be given to
moisture carryover if wet scrubbers are used. Demisting devices should be
added downstream of wet scrubbers to reduce the moisture content of the
gas stream, and the gas stream should be reheated to prevent condensation
from. occurring on the filter element. A prefilter system may be added
upstream of the HEPA system to reduce particulate loading and increase
HEPA filter life. Prefilters should be provided if the particulate
loading exceeds 2.3 mg/m? (0.001 gr/acf). The decision to install
prefilters should be based on providing the best operational balance
between HEPA filter life and capital and maintenance costs for the
prefilters. Generally, the use of a prefiltration system wil] extend HEPA
life by a factor of 2. Estimates of filter life for HEPA filters are
presented as a part of the cost analyses in Section 4.3.

The principal costs in operating a HEPA filtration system are energy
costs (i.e., fan power), replacement filters, and labor. . The frequency of
changing the filters is the primary factor affecting these costs. for
elemental phosphorus applications, replacement filters and labor may
constitute over 90 percent of the total cost of owning a system (including
capital costs) over a 20-year period.
4.2° PERFORMANCE OF ALTERNATIVE CONTROL TECHNOLOGIES

One of the primary objectives of this study is to assess the ability
of the alternative control technologies to reduce Po-210 and Pb-210 emis-
sions from nodulizing kiln or calciner operations. This subsection pre-
sents available information on the performance of each of the four primary
control techniques and establishes procedures for estimating Po-210 and
Pb-210 control efficiencies for the specific control alternatives that are

4-29


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2-7


particle size, the effectiveness of diffusion decreases and inertial
collection increases as flow velocity increases. For a given particle
size and velocity, an increase in particle density decreases the
effectiveness of diffusion and increases the effectiveness of the inertial
effect.

The HEPA filter efficiencies are based on numbers of particles
removed, not on mass removed as is common with air pollution control
devices. Parameters that are commonly used to describe HEPA filtration
performance are the efficiency, penetration, and decontamination factor
(DF). Each of these terms is defined below.

Efficiency, percent = (U-D)/U * 100 (Eq. 4-6)
Penetration, percent = (D/U) * 100 (Eq. 4-7)
Decontamination factor = U/D (Eq. 4-8)

where:
U = upstream particle count
D = downstream particle count

The DF is commonly used to compare filter performance because it
demonstrates differences between filter performances more distinctly than
either efficiency or penetration. For example, a 99.995 percent efficient
filter (DF=20,000) is twice as effective as a 99.99 percent efficient
filter (OF=10,000), and six times as effective as a 99.97 percent
efficient filter (DF=3,333).

Within a single filter, performance varies depending on particle
size. Lowest removal efficiencies (highest penetration) occur for
particles in the 0.07- to 0.12-um range (Figure 4-10). Design
efficiencies are determined by challenging the filter with 0.3 um
mondispersed DOP particles. Filters are designed to achieve efficiencies
ranging from 99.97 percent to 99.999 percent for this particle size.

The properties of a HEPA filter that are of primary concern when
designing a system are its particle collection efficiency, airflow
capacity, and pressure drop. The HEPA filters are available in a range of
sizes and capacities. The largest capacity filter available is

4-24


emissions are controlled by hooding systems with collection in scrubbers
or baghouses. Measurements conducted by EPA prior to 1983 indicate that
emissions from these operations are less than 0.001 Ci/yr for each of the
five plants. Generally, emissions from ore handling and kiln air pollu-
tion control device catch handling also can be assumed to be negligible
because all plants currently use some type of wet collection, and the
moisture in these streams will limit fugitive emissions. No data were
identified on the level of emissions from the handling of slag or ESP
catch. However, the data on plant production rates, slag generation
rates, and radionuclide concentrations in the slag presented in

Section 2.0 were used to generate "worst-case" estimates of Po-210 and
Pb-210 emission rates from siag handling. These emission estimates were
obtained by multiplying the activity levels in the slag (see Tables 2-4
and 2-5) by the annual PM emission rates determined from the following
equations for material handling (Eq. 3-1) and wind erosion from active
storage areas (Eq. 3-2):''

1,3
_ €, = Lelexio7? 2-2). oy (3-1)
(M/2) *
where
—, = materials handling PM emissions, kg/yr
U = mean wind speed, m/s
M = material moisture content, percent
W = plant P, production capacity, Mg/yr
and

E, = 2.82x10"(755) (38) (3-2)

E, = emissions from wind erosion, kg/yr/acre

S = silt content of slag, percent

P = percentage of days with >0.25 mm precipitation per year

f = percentage of time wind exceeds 5.4 m/s
As a worst case the mean wind speed was assumed to be 15 m/s, the material
moisture content 0.25 percent, the silt content 10 percent, the percentage

3-8


TABLE 5-1. PARTICLE SIZE DISTRIBUTIONS FOR Po-210 AND Pb-2104

— -

Po-210 Pb-210

Particle size, um Movin Rotary Moving Rotary
Range Median grate kiln grate kiln
<0.5 3.5 76.0 52.2 36.5 60.0
0.5-0.9 0.67 4.0 21.6 17.7 18.1
0.9-1.5 ~ 1,16 3.8 12.9 11.5 14.3
1.5-3 2.12 2.8 8.9 8.8 5.2
3-10 5.48 3.7 3.4 13.2 2.0
>10 14 9.6 1.0 12.3 0.4

@assumed to be at the outlet to a spray tower upstream from the high-
efficiency PM collector.

based on size distribution at the FMC slinger scrubber outlet.
Based on size distribution at outlet from spray tower at Stauffer.

5-5


wet ESP. The emission data presented in Table 3-5 and Figures 3-2 and 3-3
were not subjected to rigorous statistical analyses, but the graphical
displays in Figures 3-2 and 3-3 provide substantive information on the
Po-210 and Pb-210 emissions from different facilities with different
control systems. The paragraphs below discuss the overall variability of
the Po-210 and Pb-210 concentrations, with particular emphasis on the
variability of emissions over time, and identify data that can be used to
assess control device performance and the effects of new control systems
on Po-210 and Pb-210 emissions. .

The data presented in Figures 3-2 and 3-3 indicate that measured
emissions for individual test runs range over almost 3 orders of magnitude
for both Po-210 (approximately 0.1 to 30 nCi/dscm) and Pb-210 (less than
0.01 to 9 nCi/dscm). Contributors to this variability include the
inherent imprecision in the sampling and analysis method, changes in
operating conditions at a plant over time, plant to plant differences in
ore feed characteristics and calciner operating conditions, and different
levels of add-on air pollution control. The data collected to date are
not sufficient to quantify the contributions of these different mechanisms
to the overall variability in emissions. However, careful examination of
the data in Figures 3-2 and 3-3 leads to the following qualitative
observations.

1. The run-to-run variation within a given test sequence is
relatively small. Generally the largest measured concentration for a
given test is less than two to three times the smallest measured
concentration. For Po-210, the two exceptions are Test A which ranges
from about 2 nCi/dscm to 9 nCi/dsem (a factor of 4.5) and Test B which
ranges from 0.4 to 16 nCi/dscm (a factor of 40). For Pb-210, primary
exceptions are Test B which ranges from 0.04 to 0.3 nCi/dscm (a factor of
7.5), Test E which ranges from 0.02 to 0.12 nCi/dscm (a factor of 6), and
Test U which ranges from 0.04 to 0.3 nCi/dscm (a factor of 7.5). Each of
these tests was conducted on one of the two moving grate calciners. On
balance, these data suggest that variation associated with sampling and
analysis imprecision is reasonable, i.e., the variability in a 3-run test
that is attributable to sampling and analysis imprecision is likely to be
a factor of 3 or less. The data also suggest that emissions from moving
grate calciners are more variable than those from kilns.

3-15


CLEAN GAS <> DISCHARGE

HOOD

ACCESS

WATER
MANWAY DISTRIBUTOR

mm COLLECTION

PRECIPITATOR CYLINDER

HIGH VOLTAGE

INSULATOR EMITTING

ELECTRODE

PRECIPITATOR

VENTURUORAIN
BASE

GUTTER

STRAIGHTENING
VANES

bs ACCESS MANWAY
i?

GAS INLET

PRECONDITIONER

PRECIPITATOR
ORAIN

ORAIN

Figure 4-6. Circular-plate type wet esp.°

4-14


TABLE 3-4. CALCINER PM EMISSION DATA

— —

Test Concentration Emission rate
1p? Control measure? g/dscm gr/dsct kg/h 1b/h
A None 1.0 0.45 98.4 217
8 None 6.9 3.0 835 1,840
c Ss/Cyc 0.089 0.039 12.0 26.4
0 SS/Cyc 0.32 0.14 35.9 79.1
E SS/Cyc 0.14 0.063 13.7 30.3
F SS/Cyc NA NA 8.44 18.6
G SS/Cyc NA NA 8.84 19.5
H SS/Cyc 0.046 0.020 5.31 11.7
I SS/Cyc 0.062 0.027 9.44 20.8
J LEV/Ch 0.032 0.014 4.72 10.4
K LEV/Ch 0.018 0.008 2.77 6.1
L ST 0.34 0.15 77.6 171
M ST/HEV/Cyc * 0.023 0.010 4.72 10.4
Q None . 4.4 1.9 184 406
Pp ST 0.14 0.060 4.54 10.0
Q ST/WESP 0.060 0.026 1.81 4.0
R LES 0.27 0.12 49.0 108
Ss None 1.09 0.48 246 541
T LEV/Ch 0.082 0.036 21.9 48.3
U LEV/Ch 0.095 0.041 20.8 45.8
v ST 0.59 0.26 104 230
W ST/HEV/Cyc 0.027 0.012 4.90 10.8

psee references on Table 3-3.
‘SS/Cyc = slinger scrubber with cyclone mist eliminator.
LEV = low-energy venturi.
HEV = high-energy venturi.
ST = spray tower
Ch = Chevron-blade mist eliminator.
LES = low-energy scrubber.
WESP = wet electrostatic precipitator.


the gas flow evenly through the precipitator. Typical gas velocities in
the ESP chamber range from 0.6 to 2.4 m/s (2 to 8 ft/s). With an aspect
ratio of 1.5, the optimum gas velocity is generally between 1.5 to 1.8 m/s
(5 to 6 ft/s).

Resistivity is a measure of how difficult it is for a given particle
to conduct electricity. The higher the measured resistivity (the value
being expressed in ohm-cm), the harder it is for the particle to transfer
the charge. Resistivity is influenced by the chemical composition of the
gas stream and PM, the moisture content of the gas stream, and the
temperature. Resistivity must be kept within reasonable limits for the
ESP to perform as designed. The preferred range is 10° to 10'° ohm-cm.

Temperature is important because it affects resistivity and because
it affects the condensation of Po-210. The use of a spray tower upstream
from the scrubber wil] reduce the temperatures of the gas stream to about
70°C (150°F) and condense virtually all of the Po-210 in the gas stream.
4.1.4 SD/FF Systems

The SD/FF system is a multipollutant contro] system that is used to
control PM emissions as well as to reduce the concentrations of acid gases
in the stream. The SD/FF comprises two primary components--a spray dryer
or absorber and a pulse jet fabric filter. In the spray dryer, the gas
stream is cooled, vapor-phase Po-210 and Pb-210 condense on the surfaces
of the PM in the gas stream and the lime that is injected into the spray
dryer, and HF and SO, are absorbed in the lime slurry. The evaporative
cooling in the spray dryer results in a dry, particulate-laden gas :
stream. The PM is removed from the gas stream in a pulse jet fabric
filter. The paragraphs below describe the spray dryer system and the
fabric filter separately.

In the spray drying process, sorbent is injected into the gas stream
as a liquid or liquid slurry spray with sufficient moisture to promote
rapid adsorption of the acid gases. However, the evaporative cooling of
the acid gases vaporizes the moisture from the sorbent and produces a dry
PM which must be callected. Systems that have been installed on
combustors and furnaces have used varied mechanisms to introduce sorbent
to the gas stream. Sorbent may be injected through liquid nozzles or
rotary atomizers. It may be screw-fed or pneumatically blown in dry and


TABLE 5-2.

ESTIMATED FRACTIONAL EFFICIENCIES FOR VENTURI SCRUBBER
CONTROL ALTERNATIVES

a

Fractional efficiencies

Particle size, um oP _(kPay
Range Median 2.5 6.2 1o 20
<0.5 3.5 10.0 31.2 46.9 69.9
0.5-0.9 0.67 49.9 80.6 89.7 96.5
0.9-1.5 1.16 86.5 96.8 98.5 99.5
1.5-3 2.12 98.1 99.5 99.8 99.9
3-10 5.48 99.8 99.9 299.9 299.9
>10 14 >99.9 299.9 299.9 299.9

5-6


5.4 REFERENCES FOR SECTION 5

1.

3.

U. S. Environmental Protection Agency. Emissions of Lead-210 and
Polonium-210 from Calciners at Elemental Phosphorus Plants: FMC
Plant, Pocatello, Idaho. Washington, 0.C. June 1984.

U. S. Environmental Protection Agency. Emissions of Lead-210 and
Polonium-210 from Calciners at Elemental Phosphorus Plants: Monsanto
Plant, Soda Springs, Idaho. Washington, D.C. September 1984.

U. S. Environmental Protection Agency. Emissions of Lead-210 and

Polonium-210 from Calciners at Elemental Phosphorus PInats: Stauffer
Plant, Silver Bow, Montana. Washington, D.C. August 1984.

5-29


comparable to those at Stauffer. In the absence of other information,
these data suggest that distinct particle size distributions should be
used for moving grate calciners (FMC) and nodulizing kilns (al1 other
plants) in the control technology assessments. The data from the earlier
tests indicate that the cascade impactor data from Stauffer and the
Monsanto values from 1988 are the most reliable data for kiln particle
size estimates. The cascade impactor data from FMC are the only data
available for the moving grate calciner.
3.3 KILN BASELINE EMISSIONS

Baseline estimates of the annual emissions of Po-210 and Pb-210 from
each of the five operating facilities were developed on the basis of
actual emissions at the control device outlet and regulatory emission
levels. Actual baseline emission estimates are based on the most recent
emission tests conducted by either the facility or EPA. Regulatory
baseline emission estimates were based on the PM emission limits imposed
by the States and best estimates of radionuclide activity levels in PM
emissions. The results of these analyses are presented in Table 3-9.

3-21


where:
n = collection efficiency of the ESP
A = collecting plate area, nm
Q = volumetric gas flow rate, m/s
w = migration velocity, m/s

The equation indicates that ESP collection efficiency increases with
increasing values of the SCA and the migration velocity. The migration
velocity is a function of the characteristics of the emission stream
(particularly resistivity and particle size distribution) and wet ESP
design parameters such as electrode arrangement and field strengths.
Mathematically, the migration velocity can be estimated as:

weS dy ke (for dp < 5 um) (Eq. 4-21)
or .
we Sdp (for dy 5 um) (Eq. 4-22)
with peE_E
Ss ae (Eq. 4-23)
and 9
ko = 1+0.172/d) (Eq. 4-23)
where:
k, = Cunninham correction factor, dimensionless
dy = particle diameter, um
p = 30/0+2 where D is the dilectric constant (generally about 1 for
air)
E. = charging field strength, V/m
ED = collecting field strength, V/M
Ug = dynamic viscosity, g/cmes
S = constant of proportionality

In practice, w is determined empirically based on test data from similar
operations. For this study, the data from the 1983 EPA PM tests at
Stauffer were used to develop estimates for w. The procedure is described
below.

4-37


ae ee

2.0 ELEMENTAL PHOSPHORUS INDUSTRY DESCRIPTION

Phosphate rock is the basic raw material used in the production of
phosphorus and phosphorus products. About 10 percent of the phosphate
rock mined in the U.S. is used in the production of elemental phosphorus,
which is produced by a high-temperature reduction process. Environmental
releases associated with the elemental phosphorus process include air
emissions of criteria pollutants such as particulate matter (PM) and
sulfur dioxide (SO,) as well as the acid gas hydrogen fluoride (HF),
liquid effluent streams that have low pH and contain radionuclide
materials, and large quantities of slag materials that must be stored or
disposed as solid waste. The primary concern of this study is the
potential for emission of two radionuclide daughters of uranium-238
(U-238)--polonium-210 (Po-210) and lead-210 (Pb-210)--during the high-
temperature operations.

This section briefly describes the elemental phosphorus industry and
the elemental phosphorus production processes as a background for under-
standing radionuclide emission problems and control alternatives. The
discussion is divided into two subsections. The first provides an overall
description of the industry and identifies operating plants and their
capacities. The second describes the elemental phosphorus production
process, identifies production and waste streams, and presents the distri-
bution of Po-210 and Pb-210 among those streams.

2.1 INDUSTRY CHARACTERIZATION :

Elemental phosphorus is produced from the reaction of phosphate ore
with silica and carbon (coke) in a high-temperature electric furnace. The
key raw material with respect to both the product and radionuclide
emissions is the phosphate ore. Phosphate ore deposits are located
principally in three regions of the United States:

1. Southeastern region (mainly Florida, but also South Carolina,
North Carolina, and Georgia);

2. Northern Rocky Mountain region (eastern Idaho, western Wyoming,
northern Utah, and southwestern Montana); and

3. Middle Tennessee.

2-1


ws


TABLE 3-6. ACID GAS EMISSION LEVELS
HF levels $0._levels

Facility Location ppmv kg/h ppmv kg/h Ref.
FMC, Idaho Stack 18-40 6-8 200 14,15
Monsanto, Idaho Stack 1.6 17
Stauffer, Mont. Kiln 45 68 3

exhaust
Stauffer, Tenn. Kiln 180 250 2l

exhaust

Stack 0.7 64 21
Occidental, Tenn. Stack 66 774 20

a


filter type, bags will degrade or in some cases fail completely. Gas
temperatures should be kept safely below the allowed maximum. Temperature
of the inlet gas to the fabric filter is maintained at appropriate levels
by adjusting the liquid flow rate to the spray dryer.

Pressure drop in fabric filters generally is maintained within a
narrow range. For pulse jet filters, the upper end of the range typically
is 2.5 to 3.7 kPa (10 to 15 in. w.c.). Pressure drops below the minimum
indicate that either (1) leaks have developed, or (2) excessive cleaning
is removing the base cake from the bags. Either phenomenon results in
reduced performance. Pressure drops greater than the maximum indicate
that either (1) bags are "blinding," or (2) excessive cake is building on
the bags because of insufficient cleaning. The primary problem that
results from excess pressure drop is reduced flow through the system and
positive pressure in the kiln. Over time, high pressure drops also lead
to bag erosion and degradation.

4.1.5 HEPA Filters

High-efficiency particulate air filters are commonly used in
industries that require high-efficiency removal of particulate matter in
the submicron range. These stringent levels of air cleaning may be.
necessary either to protect human health or to produce a particulate-free
work environment. The HEPA technology is used extensively in nuclear,
military, pharmaceutical, aerospace, microelectronics, research, and
health care applications.

By definition, a HEPA filter is a throwaway, extended-pleated-medium,
dry filter with (1) a rigid casing enclosing the full depth of the pleats,
(2) a minimum particle removal efficiency of 99.97 percent for 0.3-um
thermally generated, monodisperse dioctylphthalate (DOP) particles, and
(3) a maximum pressure drop of 0.25 kPa (1.0 in. w.c.) when clean and
operated at rated airflow capacity. ‘?

Diffusion and inertial impaction are the primary mechanisms for
particle collection by HEPA filtration. The effectiveness of these
mechanisms varies with particle size, airflow velocity through the medium,
and, to some extent, particle density. At a constant air velocity, the
diffusion mechanism predominates as particle size decreases; inertial
impaction accounts for collection of larger sized particles. For a given

4-23


where:

Kno = inertial parameter at the throat entrance, dimensionless

dog = particle aerodynamic geometric mean diameter, cmA
Ygt = gas velocity in the throat, cm/s
= gas viscosity, g/cm s

dy = droplet diameter, cm

Cy = 0.22 + Teeth. -15N92°) (Eq. 4-15)
where:
Cy = drag coefficient for the liquid at the throat entrance,
dimensionless
Npeg = Reynolds number for the liquid droplet at the throat inlet,
dimensionless
v :
Npeg = “atta (Eq. 4-16)
g
where:
Nreo = Reynolds Number for the liquid at the throat entrance,

dimensionless
YVgt = gas velocity in the throat, ams
Yg = gas kinematic viscosity, cm 7I5
Og = droplet diameter, cm

o,s
Ing = dog (Cpx2p) . (Eq. 4-17)
where:
dng = particle aerodynamic geometric mean diameter, umA
dys = particle physical, or Stokes, diameter, um
Ce = Cunningham slip correction factor, dimensionless
Pp = particle density, g/cm
4
, = i+ (Zinio jr (Eq. 4-18)
ps

4-32


United States Office of Air Quality WiofZ BY-o22
Environmental Protection Planning and Standards EPA
Agency Research Triangle Park NC 27711 February 1989

Air

“EPA Characterization and
Control of Radionuclide |
mcm Emissions From
\@  _. Elemental Phosphorus

Production

EPA/450/3- 89/020



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5-11


PREFACE

Midwest Research Institute (MRI) prepared this report for the U. S.
Environmental Protection Agency, Office of Air Quality Planning and
Standards on Contract No. 68-02-4379, Work Assignment 12, Ms. Elizabeth
Grainger and Mr. Lee Beck served as technical project monitors.

The report was prepared by Mr. Dennis Wallace, Ms. Katy Allen, and
Mr. Jim Obremski in MRI's Environmental Engineering Department. Mr. Mark
Turner, Mr. Butch Smith, and Ms. Carol Athey provided valuable comments
and other members of the Environmental Engineering Department contributed
to specific portions of the report.

Approved for:
MIDWEST RESEARCH INSTITUTE

Pywwig le lace. fA

Roy Neulicht, Program Manager
Environmental Engineering Department.

December 12, 1988

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5-12


TABLE 3-2. NODULE COOLER EMISSION ESTIMATES

Nodule activity Estimated
Allowable, level, Ci/g ~ emissions, Ci/yr
Facility PM, Ib/h Po-210 Pb-210 Po-210 Pb-210
FMC 83 8 27 0.0034 0.009%
Monsanto 31 1.9 5.6 <0.001 0.001
Stauffer 12 4 7 <0.001¢ <0.001

®Note that these emission levels are lower than those measured by EPA in
earlier studies as reported in References 1 and 3.

3-6


TABLE 4-3. SUMMARY OF ESP EFFICIENCY CALCULATIONS

5.

Key input parameters (from test)

n 20.558,
Q = 11.35,m°/s
A= 364m
d, = 0.35 um
p
Calculate w for d = 0.35 um
w = [-In(1-n)] Q/A
= 0.0255 m/s

Calculate k, for dp = 0.35 um

ke = 140.172/0.35
= 1.491

Calculate S$

Ss w/dyke = 0.489 m/seum

Estimated values of w for different particle size ranges

d d
‘an eb mn averade, um w, m/s
<0.5 - 0.35 0.0255
0.5-0.9 0.67 0.0411
0.9-1.5 1.16 0.0651
1.5-3 2.12 0.112
3-10 5.48 0.268
>10 14 0.643

4-39


TABLE 4-1. ESTIMATED EFFICIENCY OF MONSANTO SCRUBBER

— — — _ A —

Particle diameter

Assumed Po-210 Fractional Total
Range mean fraction penetration penetration
A 8 c BxC
<0.5 0.35 0.600 0.397 0.238
0.5-0.9 0.67 0.265 0.034 0.0090
0.9-1.5 1.26 0.075 0.0011 0.00008
1.5-3 2.12 0.040 0.000097 0.000004
3-10 — $48 0.018 -- --
>10 10 0.012 -- --
TOTAL 0.25

4-34


specialty markets such as specialty steels, cast alloys, and paint
pigments. One plant sells the ferrophosphorus to a plant that processes
it to recover vanadium.

In 1980, eight elemental phosphorus plants were operating in the
U.S. However, since that time, the two Florida plants, Mobil in Pierce
and Stauffer in Tarpon Springs, have shut down as a result of high
electrical costs in that State. Recently, Monsanto dismantled its
facility in Columbia, Tennessee. Consequently, only five plants currently
are operating, and this number is not expected to increase in the
foreseeable future. Tabie 2-3 identifies the five operating plants and
presents estimates of their operating capacities for phosphorus production
and of the quantity of phosphate ore that would be required to produce
this capacity. The estimates are based on quantities published by EPA in
1983.7 During plant visits performed during July and August 1988,
industry personnel indicated that capacities had not changed since 1983.
They also indicated that production rates vary from 50 to 100 percent of
capacity depending upon market demand.
2.2 ELEMENTAL PHOSPHORUS PRODUCTION PROCESSES
2.2.1 Process Description

Elemental phosphorus is produced by a thermal process that uses
silica as a fluxing agent for the calcium present in phosphate feed ore.
Phosphate is reacted with silica and coke in a reducing atmosphere to form
elemental phosphorus (P,), CO, and calcium silicate slag. In addition,
by-product FeP is formed from the reaction of elemental phosphorus with
coke and iron oxide. Simplified equations for the process are:*

4 Ca,F(PO,) +18 $i0,+30 C + 18 Ca0*Si0,°1/9 CaF,+30 COt+3P,* (1)

(ore) © (slag)
2 P05+10 C + 10 CO++P,+ (intermediate reaction) (2)
2 Fe,0;+6C+P, + 4 FeP+6 Cot (3)

Figure 2-1 presents a simplified process flow diagram that generally
represents the process used at the five operating plants. The paragraphs

2-5


As a preconditioner upstream from a fine PM control device, a spray
tower serves three functions. First, it reduces the temperature of the
gas stream by evaporative cooling. This temperature reduction enhances
Po-210 and Pb-210 control by increasing condensation, and it reduces the
gas volume that must be treated by the fine PM control system. Second,
the spray tower reduces the concentration of SO, and HF in the control
stream by absorption. The HF is a highly soluble gas and is absorbed
readily in water. However, because SO, is less soluble than HF, a lime
slurry typically is used to enhance SO, removal. Plant personnel
contacted during this study indicate that operating spray towers generally
achieve SO, reductions of 75 percent and HF reductions of 99 percent or
more. °*? Third, the spray tower removes coarse PM from the gas stream.
Typical efficiencies for spray towers are reported to be 90 percent on
particles 5 um in diameter or greater and 60 to 80 percent on particles in
the 3 to 5 um size range.” The test data presented in Table 3-4 indicate
that a PM control efficiency of about 97 percent was achieved by the spray
tower at Stauffer.

The primary PM collection mechanism for spray towers is inertial
impaction of particles to liquid droplets. Key parameters that affect
particle collection by impaction for particles of a given size are
scrubbing zone height, gas velocity in the spray tower (generally pressure
drop (AP) across the tower is used as a surrogate), liquid-to-gas (L/G)
ratio, and spray droplet size. The pressure drop across the tower and the
L/G ratios affect operating cost as well as performance. Typical values

of operating characteristics for spray towers are:
5

ap 0.25-0.5 kPa (1 to 4 in. w.c.)
L/G ratio® 1.3 to 2.7 2/m’ (10 to 20 gal/kacfm)
Droplet size’ 500 to 1,000 um

The primary acid gas collection mechanism in spray towers is
absorption. Removal of a gaseous pollutant by absorption requires
intimate contact between the exhaust stream and the sorbent liquid. Three
steps are involved in absorption. In the first step, the gaseous
pollutant diffuses from the bulk area of the gas phase to the gas-liquid
interface. In the second step, the gas moves (transfers) across the
interface to the liquid phase. This step is extremely rapid once the gas

4-4


A major operating cost for HEPA filters is filter replacement. The
operating life of a HEPA depends on the increase in pressure drop
resulting from particle collection within the filter media. A general
guideline used to design filter systems is 4 1b/1,000 ft?/min rated
capacity (1.82 kg/1,000 ft?/min).’? Filter life was estimated by assuming
a HEPA capacity of 7.9 1b/1,000 ft°/min (3.6 kg/1,000 ft°/min) per filter
based on vendor information.*’ The methodology used to estimate filter
life consisted of the following steps:

1. Obtain particle size distribution in spray tower exit gas stream
from test data (where available);

2. Predict the mass of particles removed by prefiltration using
design prefilter removal efficiencies for a given particle size;

3. Predict mass of particles removed by HEPA filter using filter
design HEPA removal efficiencies;

4. Assume a filter capacity for HEPA filter and calculate HEPA
filter operating life with and without use of a prefilter;

5. Calculate prefilter life as two times the HEPA filter life
without the use of a prefilter; and

6. Calculate HEPA filter life as the HEPA capacity divided by the
particulate loading rate into the HEPA filter.

Estimation of the labor cost to replace prefilters and HEPA filters
as they are exhausted is based on 0.25 hours of labor per filter per
replacement cycle. For example, filter replacement for a 36 filter bank
requires 9 hours.

Exhausted filters are expected to exhibit increased concentrations of
particulate matter containing Po-210 and Pb-210. To reduce the risk of
inhalation of particles that may become airborne as a result of filter
handling during the replacement process, an automatic bagout containment
system is included in the system cost. Automatic bagout facilitates
removal of exhausted filters without direct operator contact. Heavy duty
PVC bags are installed inside the filter housing between the filters and
the housing access door. When the door is opened, the bags form a barrier
between the operator and the contaminated filter. By working through the
bag, the operator can remove the filter and draw it into the bag without
direct contact. The cost of replacement bags was included in the estimate
of replacement material cost.

4-46


ZO-AaApaamZzms x

10°

10°

410°

10”

% PENETRATION VS. PARTICLE SIZE

.07

Figure 4-10.

a 2
PARTICLE SIZE (MICRON)

The HEPA filter performance curve.

4-25



TABLE 3-5. CALCINER RADIONUCLIDE EMISSION DATA

ee _ a 7
Test Po-210 emissions Pb-210 emissions

to? Control measure? 17g nCi/dsem /ye pci/g nt iscm ye
A None 4,100 4.6 33° 39 0.04 0.029*
8 None 1,050 6.2 6.1 28 0.19 0.18¢
c $S/Cyc 17,000 1444 14° 330 0.03 0.026°
D SS/Cyc 12,000 3.04 2.6° 74 0.02 0.016°
E $S/Cyc 27,000 3.80 2.76 330 0.05 0.039°
F ss/Cye 25,000 1.47 1,24

6 SS/Cyc 29,000 1,43 1,74

H $S/Cyc 21,000 0.961 0.724

1 $S/Cyc 18,000 1.10 1.369

4 LEV/Ch 37,000 1.18 1.249

K LEV/Ch 38,000 1.96 2.049

L st 37,000 12.5 aie 9,700 3.3 5.6°
“ ST/HEV/Cye 10,000 0.23 0.354

N ST/WESP 0.23 0.34

0 None . 2,900 12.5 40°
Pp sT 37,000 4.88 1,2¢ 4,800 0.65 0.16°
Q ST/WESP 31,000 1.61 0.37¢ 4,600 0.25 0.056°
R LES 850 0.23 0.364 180 0.049 0.0754
s None 4,400 4.8 8.0° 180 0.20 0.32°
T Lev/Ch 55,000 4.5 9.0¢ 200 0.015 0.030°
u LEV/Ch 51,000 4.9 7.9 1,300 0.12 0.19°
v st : 39,000 23 30° - 2,200 7.3 9.5¢
w ST/HEV/Cyc 35,000 0.95 1,4¢ 8,200 0.23 0.34¢

Se

——
see references on Table 3-3.
®ss/cye = slinger scrubber with cycione mist eliminator.
LEV = low-energy venturi.
HEV = high-energy venturi.
ST = spray tower
Ch = Chevron-blade mist eliminator.
LES = low-energy scrubber.
WESP = wet electrostatic precipitator.
afssunes plant operates 85 percent of time.
sed on facility assumptions on operating rates.
"assumes plant operates 95 percent of time.


12.

13.

14,

15.

16.

7,

18.

19,

20.

al.

22.

Radian Corporation. Emission Testing of Calciner Off-Gases At FMC
Elemental Phosphorus Plant, Pocatello, Idaho. Emission Test Final
Report, Volume I. Prepared for U. S. Environmental Protection Agency
under Contract No. 68-07-3174. Research Triangle Park, North
Carolina. August 1984.

Letter from Hebert, F., FMC, to O'Neal, G., EPA. September 6,
1985. Summary of 1985 emission test results.

Letter from Bowman, M., FMC Corporation, to Magno, P., EPA/ORP.
February 26, 1988. Summary of FMC emission data.

Memo and attachments from Wallace D., and K. Leeds, Midwest Research
Institute, to Beck, L., EPA/ISB. August 9, 1988. Site Visit--FMC
Corporation, Pocatello, Idaho.

Radian Corporation. Emission Testing of Calciner Off-gases at
Monsanto Elemental Phosphorus Plant, Soda Springs, Idaho. Emission
Test Final Report, Vol. I. Prepared for U. S. Environmental
Protection Agency under Contract No. 68-02-3174. Research Triangle
Park, North Carolina. August 1984.

Memo and attachments from Wallace, 0., and K. Leeds, Midwest Research
Institute to Beck, L., EPA/ISB. August 9, 1988. Site Visit--
Monsanto Elemental Phosphorus Plant, Soda Springs, Idaho.

Letter from Wind, 0., Monsanto Chemical Company, to McLaughlin, T.,
EPA/ORP. May 10, 1988. Emission data from Monsanto, Soda Springs,
facility.

Radian Corporation. Emission Testing of Calciner Off-Gases At
Stauffer Chemical Elemental Phosphorus Plant, Silver Bow, Montana.
Emission Test Final Report, Volume I. Prepared for U. S.
Environmental Protection Agency under Contract No. 68-07-3174.
Research Triangle Park, North Carolina. August 1984.

Memo and attachments from Wallace, D., and J. Obremski, Midwest
Research Institute, to Beck, L., EPA/ISB. August 23, 1988. Site
Visit--Occidental Elemental Phosphorus Plant, Columbia, Tennessee.

Radian Corporation. Oraft Final Emission Test Report, FMC Elemental
Phosphorus Plant, Pocatello, Idaho. Prepared for U. S. Environmental
Protection Agency under Contract No. 68-02-4338. Research Triangle

Park, North Carolina. October 1988.

Radian Corporation. Draft Final Emission Test Report, Monsanto
Elemental Phosphorus Plant, Soda Springs, Idaho. Prepared for U. S.
Environmental Protection Agency under Contract No. 68-02-4338.
Research Triangle Park, North Carolina. October 1988.

3-24


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5-20


Figure 4-1. Countercurrent flow spray tower.'

4-3


23. Memo and attachments from Wallace, 0., and J. Obremski, Midwest
Research Institute, to Beck, L., EPA/ISB. August 23, 1988. Site
Visit--Stauffer Elemental Phosphorus Plant, Mount Pleasant,
Tennessee.

3-25


tensile strength of the media, which is related to media rupture under
high overpressure, and its water repellency, which is related to the
plugging that produces the high overpressure.

The sealant is the most sensitive component of the filter apparatus
with respect to environmental conditions. The sealant traditionally used
to seal the fiber core into the frame is a heat- and moisture-resistant
elastomeric adhesive. Commonly used sealants are chemically expanded
self-extinguishing urethane foam; solid urethane; neoprene; or silicone.
Filters that will be operated continuously at high temperatures of about
200°C (400°F) may be sealed with compressed glass-fiber matting,
refractory adhesives, or silicone. The qualities desirable in a sealant
are (1) moisture and corrosion resistance, (2) ability to withstand
radiation exposure and alternating exposure to heat and cold or dry to
humid air, and (3) maintenance of seal integrity at design operating
conditions and potential transient conditions.

Filter frames are available in a variety of fire-retardant materials
including rigid urethane, 1.9-cm (0.75 in.) exterior grade particle board,
1.9-cm (0.75-in.) plywood, 14 gauge Type 409 or 304 stainless steel, or
zinc or aluminum coated steel. Metal frames are selected when a high
degree of corrosion resistance is required, or when continuous wetting or
high humidity at high temperatures is expected. Under these conditions,
wood frames have been found to absorb moisture and swell, rupturing the
filter-to-frame seal and permitting filter by-pass to occur. The sides of
the filter are sealed to the frame with an appropriate sealant. When high
sound or vibration levels are expected, wood frames are preferred over
metal ones (other factors being equal) because of their superior vibration
damping characteristics.

Prior to operation, one or more HEPA filters are mounted into a
filter housing that consists of the requisite number of holding frames to
accommodate the number of filters to be installed. The housing typically
is zinc- or aluminum-coated corrosion-resistant steel, or stainless
steel. Critical aspects of the mounting fixture are (1) the structural
integrity; (2) tolerances on dimensions, flatness, alignment, and the
finish of the filter seating surface; (3) the method of sealing the
mounting fixture into the filter housing; (4) rigidity of filter clamping
devices; and (5) the degree and uniformity of filter gasket compression.

4-28


The first step in developing size-specific values for w was to
estimate S, as a constant, based on the measured removal efficiency for
the smallest fraction of PM at Stauffer. This constant value for S was
then used to estimate size-specific migration velocities using
Equations 4-21, 4-22, and 4-23. Table 4-3 summarizes the calculations
used to determine S and presents estimates of w for the different size
ranges of Po-210 emissions that were measured by EPA during the 1983 test
program. These values of w are used to estimate control efficiencies for
the different wet ESP control alternatives presented in Section 5.

Data from sites other than Stauffer are not available to assess the
validity of the ESP model. However, the overall efficiency for Po-210 as
measured by the EPA Method 5 tests at Stauffer was compared to the
predicted efficiency based on the migration velocities reported in
Table 3-2. The Method 5 tests measured an inlet concentration of Po-210
of 4.88 nCi/dscm and an outlet concentration of 1.61 nCi/dscm, a reduction
of 67 percent. The model based on the impactor inlet data also estimated
a 67 percent efficiency. Consequently, the model appears to yield
consistent results for Stauffer. However, data are not available to
determine how well the model can be generalized to other facilities and to
control systems with different design parameters.

4.2.3 SO/FF Systems

Estimation of the efficiency of SD/FF systems in removing Po-210 and
Pb-210 from the nodulizing kiln/calciner exhaust is much more complicated
than was the case for venturi scrubbers or wet ESP's because information
on the performance of these systems is quite scarce. No specific informa-
tion was found on the removal of Po or Pb emissions from metallurgical
furnace exhaust streams, and only limited information was obtained for Pb
removal from combustion gas streams. Further, no general models are
available on the performance of fabric filters, and data are not adequate
to establish the effect of spray dryers on fabric filter performance.
Hesketh notes that pulse jet PM emissions are unusual in that large
particles may be released because of the agglomeration and the high
cleaning energy. '” Fractional particle size collection has little
practical significance because size and number concentrations change
radically over the filtration/cleaning cycle. For any specific

4-38


TABLE 3-7. PARTICLE SIZE DISTRIBUTION BASED ON IMPACTOR SAMPLES

— — _ —
Percentage of poilutant in size range

Control Facility/ Approximate particle size D-50 ——

Pollutant level location DST OST 53 STO TO

Po=210 None FMC/2-1 33.5 3.9 4.9 5.8 18.0 33.9
FMC/2-2 23.8 2.6 3.8 5.2 15.6 49.0
FMC/1 65.0 7.5 6.0 6.9 7.6 7.0
Low-energy FMC/2-2 70.7 6.1 7.5 5.6 6.8 3.3
scrubber FMC/1-1 71.6 3.1 1.6 1.3 1.9 20.4
FMC/1-2 85.8 2.9 2.3 1.4 2.5 5.1
Stauffer 52.2 21.6 12.9 8.9 3.4 1.0
Monsanto 60.0 26.5 6.8 4.7 1.4 0.6
ESP Stauffer 50.1 23.5 16.5 44 3.5 2.0
Venturi Monsanto 70.0 18.0 5.3 4.7 1.4 0.6
FMC/1 72.5 7.8 5.7 5.5 5.8 2.7
Pb-210 None FMC/2-1 415 6.2 9.5 11.8 13.0 18.0
FMC/2-2 12.4 2.4 1.8 1.3 32.3 49.7
FMC/1 30.0 12.5 13.3 12.2 19.0 13.0
Low-energy FMC/2-2 61.2 11.8 4.6 8.8 9.5 4.0
scrubber FMC/1-1 26.9 17.9 21.4 4.8 13.1 15.8
FMC/1-2 21.3 23.4 8.5 12.8 17.0 17.0
Stauffer 60.0 18.1 14,3 5.2 2.0 0.4
Monsanto 60.0 26.5 7.5 4.0 1.8 0.2
ESP Stauffer 54.1 22.4 14.1 4.9 3.3 1.2
Venturi Monsanto 60.0 26.5 8.5 3.5 1.2 0.3
FMC/1 53.5 14.5 11.0 10.5 8.2 2.3
- — — _

3-19


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TECHNICAL REPORT DATA
(Please read Insiructions on the reverse before compieringy

7, REPORT NO. 3-59. ony 2. 3. RECIPIENT'S AGCESSION NO.
EPA-450/3=68-015

la. TITLE AND SUBTITLE 5. REPORT DATE
Characterization and Control of Radionuclide February 1989

Emissions From Elemental Phosphorus Production 6. PERFORMING ORGANIZATION CODE

7 AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NO.
19, PERFORMING ORGANIZATION NAME AND AOORESS 10. PROGRAM ELEMENT NO.
Midwest Research Institute Work Assignment 12
Suite 350 [17. CONTRACT/GRANT NO.
401 Harrison Oak Blvd EPA Contract No. 68-02-4379
Cary, NC 27513
12. SPONSORING AGENCY NAME AND ADDRESS 13. TYPE OF REPORT AND PERIOD COVERED
Elizabeth A. Grainger, Project Officer May 1988 to February 1989
Industrial Studies Branch, Emissions Standards Division |'* SPONSORING AGENCY CooE

OAQPS
U.S. Environmental Protection Agency, RIP, NC 27711
15. SUPRLEMENTARY NOTES

TE ABSTRACT Thig report presents the results of a study conducted by the Industrial
Studies Branch in EPA's Office of Air Quality Planning and Standards that was designed
to collect background information on radionuclide emissions from elemental phosphorus
production processes. The Office of Radiation Programs will use this information to
evaluate the National Emission Standard for Hazardous Air Pollutants for radionuclide

emissions from elemental phosphorus production in response to litigation by the Sierra
ub.

Information gathered included all emission data generated over the past 10 years
by EPA and elemental phosphorus facilities, test results of the test program conducted
concurrently with this study (two scrubbers), data compiled from plant visits to each
lof the five operating facilities, and data acquired through review of published
literature, contact with knowledgeable EPA personnel, and telephone contacts with
control equipment vendors.

This report provides descriptions of the elemental phosphorus production processes,
radionuclide emissions from those processes, availability of control techniques that
could reduce those emissions, and the performance and costs of alternative control
techniques.

H7. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS Ib. IDENTIFIERS/OPEN ENOED TERMS jc. COSATI field/Group

Elemental phosphorus
production, air pollution,
air emission, air
pollution control equip-
ment, air emission

Elemental Phosphorus production, air
emissions, radionuclide emissions, acid
gas emissions, particulate matter emissiong
spray towers, scrubber, ESP, fabric filter
high efficiency particulate air filter

standards
18. DISTRIBUTION STATEMENT 19. SECURITY CLASS /This Report) 21. NO. OF PAGES
20. SECURITY CLASS «This page) (22. PRICE

EPA Form 2220-1 (Rev. 4077) = = EviOUS EDITION. OBSOLETE


This report has been reviewed by the Emission Standards Division of the Office of Air Quality Planning and
Standards, EPA, and approved for publication. Mention of trade names or commercial products is not intended
to constitute endorsement or recommendation for use. Copies of this report are available through the Library
Services Office (MD-35), U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711,
or from National Technical Information Services, 5285 Port Royal Road, Springfield, Virginia 22161.


As discussed in Section 4.3, the measured efficiencies for Po~-210 and
Pb-210 at Monsanto were significantly higher than the efficiencies
estimated by the scrubber model. Consequently, the estimated scrubber
efficiencies estimated by the model were adjusted to compensate for the
apparent low bias of the model. Table 5-4 presents the estimates of
scrubber performance for the four control alternatives for Po-210 and
Pb-210 for rotary kiln and moving grate calciners. The left half of this ,
table presents the modeled results based on the data presented in
Tables 5-1 and 5-2. The right half of the table presents the adjusted
results. The basis for these adjusted results and the calculation
procedures are documented in Reference 4.

The adjusted efficiencies presented in Table 5-4 were applied to the
emission rates presented above to estimate controlled emissions under each
of the four venturi scrubber options. The results are presented in
Tables 5-5 and 5-6. These emission rates presented in Tables 5-5 and 5-6
were compared to the baseline emission rates presented in Table 3-7, and
emission reductions were calculated. These results are presented in
Table 5-7 for Po-210 and 5-8 for Pb-210.

Control efficiencies also were developed for the SD/FF and the HEPA
using the procedures described in Section 4.2. Efficiencies for the SD/FF
system were calculated based on an assumed outlet loading of 0.023 g/dscm
(0.01 gr/dscf) and estimated inlet loadings of 13 g/dscm (5.7 gr/dscf) for
rotary kilns and 15 g/dscm (6.7 gr/dscf) for moving grate calciners. :
These inlet loading estimates are based on the uncontrolled PM emission
rates measured at FMC and Stauffer in 1984 and the quantity of lime added
to the system to control SO, at concentrations of 500 ppmv and HF at
1,500 ppmv.'*? The resultant efficiencies are 99.82 percent for rotary
kilns and 99.85 percent for moving grates. For the HEPA filter, the
efficiency was assumed to be 99.998 percent as described in Section 4.2.4.

The estimated efficiencies defined above then were used to estimate
Po-210 and Pb-210 emissions for each of the five operating facilities.
Since the HEPA filter is installed downstream from a spray tower, the
emission rates presented above were used as "uncontrolled" emission
rates. The SD/FF system does not include a spray tower. Consequently,
"uncontrolled" emissions were estimated using the spray tower outlet rates
defined above and the assumption that the spray tower is almost 65 percent

5-8


The performance of a wet ESP is affected by design and operating
properties of the system as well as flue gas conditions. Key design
characteristics include the specific collection area (SCA), the aspect
ratio, and gas flow distribution. Key operating characteristics include
particle size resistivity, temperature, and H,0 content of the gas stream.

The SCA is defined as the ratio of collection surface area to the gas
flow rate into the collector. Expressed in metric units,

2
sca = total collection surface, m (Eq. 4-1)
1,000 m/h

Increases in the SCA of a precipitator design will, in most cases,
increase the collection efficiency of the precipitator. Most conservative
designs call for an SCA of 20 to 25 n per 1,000 m/h (km? /h) (350 to
400 ft” per 1,000 acfm [kacfm]) to achieve a collection efficiency of more
than 99.5.percent. The general range of SCA is between 11 and 45 io per
km’ /h (200 and 800 ft? per kacfm), depending on precipitator design
conditions and desired collection efficiency.°** The wet ESP currently
operating on a nodulizing kiln has an SCA of about 9.3 m’/km’/h
(170 ft?/kacfm).

The aspect ratio (AR) is the ratio of the effective length to the
effective height of the collector surface. The AR can be calculated using

Equation 4-2.

AR = efpect ve Tenth a (Eq. 4-2)
Typical AR's for ESP's range from 0.5 to 2.0. However, for high-
efficiency ESP's (those having collection efficiencies of >99 percent),
the AR used in precipitator design should be greater than 1.0, usually 1.0
to 1.5.

Gas flow through the ESP chamber should be slow and evenly
distributed through the unit. The gas velocities in the duct leading into
the ESP are generally between 6 to 24 m/s (20 and 80 ft/s). The gas
velocity into the ESP must be reduced for adequate particle collection.

This velocity reduction is achieved by using an expansion inlet plenum.
The inlet plenum contains perforated diffuser plate openings to distribute

4-16


4.1 DESCRIPTION OF APPLICABLE CONTROL SYSTEMS

The four fine PM control techniques examined during this study are
wet electrostatic precipitators (wet ESP's), venturi scrubbers, spray
dryers with pulse jet fabric filters (SD/FF's), and high-efficiency
particulate air (HEPA) filters. The wet ESP and venturi scrubber were
selected because they are the control] systems that are used at operating
elemental phosphorus plants. The SD/FF and HEPA were selected as high-
efficiency PM control devices that have excellent potential for
controlling Po-210 and Pb-210 emissions but that have not been applied to
elemental phosphorus plants. The SD/FF systems have been applied
successfully to combustion sources and mineral and metallurgical furnaces

- and have demonstrated high control efficiencies for condensible metals and
acid gases. The HEPA filter has been demonstrated to achieve high control
efficiencies on radionuclide emissions from uranium industry processes.

Four of the five operating elemental phosphorus facilities currently
operate spray towers as either the primary control system or as a gas
conditioning technique. These spray towers will remove coarse PM as well
as acid gases from the gas stream. All of the control techniques, except
the SD/FF, can benefit from inclusion of a spray tower upstream of the
primary fine PM control device to reduce temperature, gas volume, and acid
gas concentration.

The five subsections below address spray towers and the four fine PM
control techniques individually. Each section includes a description of
the control technique, a discussion of the operating principles for the
technique, and identification of the key design and operating parameters.
4.1.1 Spray Towers

A spray tower is one of the most simply constructed wet scrubbers,
comprising a cylindrical vessel constructed of steel, plastic, or wood and
one or more sets of nozzles that are used to spray liquid into the gas
stream. The exhaust gas generally enters the bottom of the tower and
Moves upward as shown in Figure 4-1.' Liquid, generally water or a slurry
of water and lime, is sprayed downward from one or more levels to provide
a countercurrent flow of liquid and gas in the tower. This countercurrent
flow exposes the exhaust gas with lowest pollutant concentration to the
freshest scrubbing liquor.


performance and cost are that sufficient moisture will be added to reduce
gas temperature to 120°C (250°F) at the inlet to the FF, that lime will be
added at a 1.5 stoichiometric ratio for HF and SO, combined, and that a
pulse jet fabric filter capable of maintaining an outlet grain loading of
0.023 g/dscm (0.01 gr/dscf) will be installed.

The final control alternative comprises a spray tower scrubber, a
reheat system, a prefilter, and a HEPA filter in sequence. The spray
tower is used to reduce the acid content of the gas stream and to remove
larger sized PM. The reheat system is needed to raise the gas stream
temperature sufficiently to prevent condensation of moisture and inorganic
acids in the HEPA filter. The prefilter is used to reduce the PM loading
to the HEPA filter and thereby extend its life. The HEPA filter system
has not been applied to elemental phosphorus facilities and generally is
not applied to furnaces that generate gas volumes as large as those
generated by elemental phosphorus process calciners or nodulizing kilns.
However, the system was selected for consideration because HEPA filters
have been used successfully to control radionuclide emissions from uranium
processing facilities and they do provide a much greater level of control
than is provided by the other control alternatives.

5.2 PERFORMANCE OF CONTROL ALTERNATIVES

The performance of each of the 10 control alternatives was calculated
based on the reduction from baseline emissions that could be achieved by
application of the control alternative. For each control alternative and
each operating facility, annual emissions of Po-210 and Pb-210 were
estimated using the procedures described in Section 4. These estimated
emission levels were compared to the baseline emission estimates that are
presented in Table 3-9 to determine achievable emission reductions.

Performance models for venturi scrubbers and wet ESP's are presented
in Sections 4.2.1 and 4.2.2, respectively. Application of these models
requires information on the emission rate of Po-210 and Pb-210 at the
venturi and ESP inlet and on the particle size distribution of these
emissions. The estimates of Po-210 and Pb-210 emission rates at the


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2.3
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10.

11.

REFERENCES FOR SECTION 2

Bureau of Census, U. S. Department of Commerce. Current [ndustrial
Reports: Inorganic Chemicals. Washington, 0.C. 1968-1987.

Stula, R. T., R. E. Balanger, C. L. Clary, R. F. May, M. E. Spaeth,
and J. P. Swenson. Airborne Emission Control Technology for the
Elemental Phosphorus Industry, Final Report for EPA Contract

No. 68-01-6429. Science Applications, Inc. La Jolla, California.
January 1984,

U. S. Department of the Interior, Preprint from the 1985 Minerals
Yearbook: Phosphate Rock. Pittsburgh, Pennsylvania. 1986.

Eadie, G. and 0. Bernhardt. Radiological Surveys of Idaho Phosphate
Ore Processing--The Thermal Process Plant. Prepared for U. S.
Environmental Protection Agency. Las Vegas, Nevada. Technical Note
ORP/LV-77-3. November 1977.

U. S. Environmental Protection Agency. Emissions of Lead-210 and
Polonium-210 from Calciners at Elemental Phosphorus Plants: Monsanto
Plant, Soda Springs, Idaho. Washington, 0.C. September 1984.

Andrews, V. Emissions of Naturally Occurring Radioactivity:
Stauffer Elemental Phosphorus Plant. Prepared for U. S.
Environmental Protection Agency. Las Vegas, Nevada. Publication
No. EPA-520/6-82-019. November 1982.

Andrews, V. Emissions of Naturally Occurring Radioactivity:
Monsanto Elemental Phosphorus Plant. Prepared for U. S.
Environmental Protection Agency. Las Vegas, Nevada, Publication
No. EPA-520/6-82-021. November 1982.

U. S. Environmental Protection Agency. Emissions of Lead-210 and
Polonium-210 from Calciners at Elemental Phosphorus Plants: FMC
Plant, Pocatello, Idaho. Washington, D.C. June 1984.

Radian Corporation. Oraft Final Emission Test Report, Monsanto
Elemental Phosphorus Plant, Soda Springs, Idaho. Prepared for U. S.
Environmental Protection Agency under Contract No. 68-02-4338.
Research Triangle Park, North Carolina. October 1988.

U. S. Environmental Protection Agency. Emissions of Lead-210 and
Polonium-210 from Calciners at Elemental Phosphorus Plants: Stauffer
Plant, Silver Bow, Montana. Washington, D.C. August 1984.

Memo and attachments from Wallace., D., and K. Leeds, Midwest
Research Institute, to Beck, L., EPA/ISB. August 9, 1988. Site
Visit--FMC Corporation, Pocatello, Idaho.


TABLE 5-3.

ESTIMATED FRACTIONAL EFFICIENCIES FOR WET ESP
CONTROL ALTERNATIVES

—

—

Fractional efficiencies

Particle size, um SCA (m/s~)
Range Median = 39.4 78.8 118 158
<0.5 3.5 63.4 86.6 95.1 98.2
0.5-0.9 0.67 80.2 96.1 99.2 99.8
0.9-1.5 1.16 92.3 99.4 99.9 299.9
1.5-3 2.12 98.8 299.9 . 299.9 >99.9
3-10 5.48 299.9 299.9 299.9 299.9
>10 14 299.9 >99.9 >99.9 299.9

5-7

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Control Alternative
Annualized Costs

Control
VS/10
VS/25
Vs/40
VS/80
WESP/200
WESP/400
WESP/600
WESP/800 aE
SD/FF WE Gi
HEPA (UMMM G;
i) 10 20 30 40 50
 Cost-$ Millions
Ml Féc Monsanto [—] Occidental

Stauff,MT Stauff,TN

Figure 5-2. Annualized costs of control alternatives.


Figure 4-3. Wetted-throat venturi scrubber.'.

4-8


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(0.6 m)x(0.6 m)x(0.3 m) ([24 in.]x[24 in. ]x{11.5 in.]) and is rated at
57 m/min (2,000 ft? /min) airflow. To accommodate large airflows,
multiple filters are arranged in banks. Filters usually are removed and
replaced when the pressure drop across the filter reaches twice the clean
filter pressure drop, i.e., 0.5 kPa (2.0 in. w.c.).

The environmental conditions to which the filter system will be
exposed must be considered when designing a HEPA filter system. Key
environmental parameters requiring consideration are temperature,
moisture, corrosion potential, and vibration potential. The combined
influence of these parameters will affect the selection of a filter for a
particular application. Unfortunately, the application of HEPA filters to
severe environmental conditions often requires a compromise in filter
properties. Manufacturers frequently have information on the ability of
components used in the construction of filters to resist chemical or
environmental factors, but the combined effects of humidity, chemical
agents, and heated air upon filters and the interrelationship with the
construction materials are typically unknown. Destructive environmental
testing is recommended when the suitability of a filter for a specific
environment is in doubt.

A HEPA filter consists of five components: the filter medium, the
medium separators (optional), the media-to-frame sealant, the filter
frame, and the filter housing. Figure 4-11 is a schematic of a typical
filter and arrangement of multiple filters in a filter bank.

The filter medium may be folded and supported by corroguated metal
separators, typically aluminum, or be preformed and self-supporting. It
may be composed of asbestos, cellulose, microglass fibers, plastics, or
ceramic materials, or blends thereof. Fire-resistant filter media are
usually composed of fiberglass, sometimes with a small percentage of
asbestos added to improve resistance to HF, or ceramic material.
Proprietary media designed for enhanced HF resistance are available. The
HEPA filter media are rated at 100 percent relative humidity conditions
and will tolerate both high humidity and direct wetting. However, exces-
sive amounts of moisture, either from airborne droplets or condensation on
the element can completely plug the filter and result in failure by over-
pressure. The important factors in moisture resistance are the wet

4-26


2
= i ‘
“ttt 7 atte 7 =
tt t : ;
102 et rh i = r +t
3 ——
Ss...
3-
as
¢
z, Polonium Lead
3 = 2
& ot ae f
& pr ‘. =
| q ‘
I t a =
I rf : r —t
t i t r = i
} i —. if if if 4. 4
L if T T Tt T 7 if

400 600 300 1000 1200 1400 1300
Temperacure (*C)

Figure 3-1. Vapor pressure curves for Po and Pb.

3-4



assumed to be $20/ton. The waste is considered to be hazardous for these
calculations because of the concentration of radioactive material. (For
comparison, it should be noted that the cost of disposing of nonhazardous
wastes is approximately $5/ton.)
4.3.1 Venturi Scrubber Cost Assumptions

The capital and annualized costs for venturi scrubbers were based on
procedures established in the GARD manual and on equipment costs
established therein. Because of the large airflow encountered at most
kilns, two identical scrubber systems in parallel were costed on one-half
of the total exhaust stream. Radial fans were costed because of their
ability to operate at high pressures and temperatures in an abrasive gas
stream. The costs of the starter motor, direct and V-belt drives, and’
dampers are included in the fan costs. The corrosiveness (fluorides) of
the gas stream entering a scrubber from the rotary kiln calciner requires
that fabricated equipment cost estimates be based on the use of a
combination of Hastelloy and Type 316 stainless steel. Plate thickness of
the fan housing and ductwork was determined based on system static
pressure. Details on the cost inputs for venturi scrubber contro] options
for each facility are presented in Appendices A through £ for the
individual facilities.
4.3.2 Wet ESP Cost Assumptions

Capital and annualized costs far the ESP were based on an EPA cost
update. '°+?° The primary factor, other than SCA, that affects ESP costs
is material of construction. The corrosiveness (fluorides) of the gas
stream entering an ESP from the rotary kiln calciner requires that
fabricated equipment the ductwork and ESP housing be constructed of a
corrosion resistant material. Costs for these components were based on
the use of Type 316 stainless steel. Collecting electrodes also were
assumed to be constructed from Type 316 stainless steel.
4.3.3 SD/FF Cost Assumptions

Spray dryer/fabric filter systems provide efficient collection of
both condensible PM and acid gases. Key design parameters that affect
system performance and costs are lime addition, gas temperature entering

the FF, FF air-to-cloth ratio, and pressure drop through the system. Lime
addition rates were calculated under the assumption of a 1.5:1

4-44


Most of the phosphate rock used in this country's phosphate rock and
phosphate fertilizer industries is taken from Florida reserves, but most
of the ore used in elemental phosphorus production is obtained from the
Tennessee and Rocky Mountain regions. The phosphate ores from the three
principal regions are distinct in their radiological characteristics.
Generally, ores from the southeastern region have the highest radionuclide
concentrations, followed respectively by those from the northern Rocky
Mountain region and those from middle Tennessee. The radioactivity
content of phosphate rocks from different deposits within the same general
region, however, may vary widely. Details on the radioactivity levels of
the ores used at operating elemental phosphorus plants are presented in
Section 2.2.

The principal products of the elemental phosphorus industry are
elemental phosphorus and two by-products associated with its production--
calcium silicate slag and ferrophosphorus (FeP). The production rates of
elemental phosphorus for the years 1967 through 1987 are shown in
Table 2-1." Typically, calcium silicate slag is produced at a rate of 8
to 9 Mg per Mg of elemental phosphorus produced, and ferrophosphorus is
produced at a rate of 0.1 to 0.3 Mg per Mg of elemental phosphorus
produced. *

Elemental phosphorus is used primarily in the manufacture of high-
grade phosphoric acid, which serves as a feedstock in the production of
chemicals and food products. In 1986, 50 percent of the supply was used
to produce sodium tripolyphosphate, and small quantities (about 20,000 Mg)
were exported. ? End uses include detergents, metal treatment, foods and
beverages, and chemicals. *

Historically, the calcium silicate slag produced in this process has
been used as an aggregate material. Some of the uses of this material are
given in Table 2-2.7 However, as outlined in Section 2.2.2., this slag
may contain Po-210 and Pb-210, and it has been demonstrated to contain
U-238. Consequently, concerns have been raised about use of the
material. Information collected from plant visits during this study
indicates that most slag currently is being stockpiled at plant sites.

The other major by-product is ferrophosphorus. Plant contacts
indicated that the market for this product is limited, but some is sold in

2-2


f Sheet er
Fae Pater

Benween ¢viter Pack 1 Meine

Adheswe Gone
anet integra: Frame

Figure 4-11. Examples of HEPA filter systems?

4-27


Cunningham slip correction factor, dimensionless
absolute temperature, K
particle physical, or Stokes, diameter, um

iz)
at
ou

a
vg
a
”

3
ve + CZ ae 2 (Eq. 4-19)

where:
Ygt = gas velocity in throat, cm/s
AP = pressure drop, cm H20
L/G = volumetric liquid-to-gas ratio, dimensionless

In general, only the pressure drop and L/G ratio were allowed to vary in
the analyses conducted during this study. All other values were held
constant at the following levels:

by = 1,000 kg/m”

Og = 1.0 kg/m :

ug = 2.0x10"° g/cmes”

Yq = 0.2 cm’/s :

Emission testing was conducted recently at the inlet and outlet of a
high-energy venturi scrubber at the Monsanto facility in Soda Springs,
Idaho. The data in Section 3.0 indicate that the Po-210 emissions were
measured at 23 nCi/dscm at the inlet and 0.95 nCi/dscm at the outlet, a
reduction of about 96 percent. The particle size distribution estimates
from the 1988 EPA tests at the Monsanto spray tower outlet was used to
estimate the Po-210 control efficiency using the above equations. The
results, which are tabulated in Table 4-1, estimate that the overall
efficiency of the venturi scrubber in controlling Po-210 would be about

75 percent, a level that is significantly less than the measured value
obtained by Monsanto. Two factors may have contributed to this large
difference as described below.

First, the data in Table 4-1 illustrate the sensitivity of these
calculations to the particle size distribution, particularly the
distribution in the submicron fraction. The particle size distribution
that was used for these calculations introduces uncertainty to the

4-33


TABLE

TABLE
TABLE

TABLE

TABLE
TABLE
TABLE

TABLE
TABLE

TABLE

TABLE

TABLE

TABLE

TABLE

TABLE

TABLE

TABLE
TABLE

§-3.

5-4.
5-5.

5-6.

5-7.
§-8.
5-9.

5-10.
§-11.

§-12.

§-13.

5-14,

5-15.

5-16.

§-17.

5-18.

5-19.
5-20.

LIST OF TABLES (continued)
ESTIMATED FRACTIONAL EFFICIENCIES FOR WET ESP CONTROL
ALTERNATIVES........200- ee ecceee rrr SS Srrrr rrr
ESTIMATED PERFORMANCE FOR VENTURI SCRUBBER OPTIONS.....

ESTIMATED Po-210 EMISSION LEVELS ACHIEVED BY CONTROL
ALTERNATIVES. oc ccccccccccccccsscccscccccccsccscscees

ESTIMATED Pb-210 EMISSION LEVELS ACHIEVED BY CONTROL
ALTERNATIVES... .eccccceccesccccscccsevcccsesceceees .

REDUCTION OF Po-210 EMISSIONS FROM BASELINE............
REDUCTION OF Pb-210 EMISSIONS FROM BASELINE.......--0--
CAPITAL COST OF CONTROL ALTERNATIVES......cceeeeeeeeees

ANNUALIZED COST OF CONTROL ALTERNATIVES.......... sees

SUMMARY OF COSTS FOR VENTURI SCRUBBER--10 INCH
PRESSURE DROP... ...sccecsccccccccccnccscsccsccescacs .

SUMMARY OF COSTS FOR VENTURI SCRUBBER--25 INCH
PRESSURE DROP... ...eecccscscccccccceccceccccsesceecs

SUMMARY OF COSTS FOR VENTURI SCRUBBER--40 INCH
PRESSURE DROP. ......sececccececcecccccccccscescccsees

SUMMARY OF COSTS FOR VENTURI SCRUBBER--80 INCH
PRESSURE DROP...... Pree e rer er ye rrererrerr rer ers sseeee

SUMMARY OF COSTS FOR WET WALLS ELECTROSTATIC/
PRECIPITATOR--200 SCA... .cseccccscccscccncsccccceeses

SUMMARY OF COSTS FOR WET WALLS ELECTROSTATIC/
PRECIPITATOR--400 SCA........- dene eceaccccscsccccees :

SUMMARY OF COSTS FOR WET WALLS ELECTROSTATIC/
PRECIPITATOR--600 SCA... .escesecscceccnccccecnceces .-

SUMMARY OF COSTS FOR WET WALLS ELECTROSTATIC/
PRECIPITATOR--800 SCA....cecsccececceccececerccsseees

SUMMARY OF COSTS FOR SPRAY DRYER/FABRIC FILTER........ .
SUMMARY OF COSTS FOR HEPA FILTRATION SYSTEM...... aeeeee

vi

5-7
5-9

5-10

5-11
5-12
5-13
§-15

5-19

5-20

5-21

5-22

§-23

5-24

5-25

5-26
5-27
5-28


efficient in removing Po-210 and Pb-210 from the exhaust stream. This
65 percent efficiency estimate is based on the performance measured by EPA
at Stauffer.’ The resulting emission estimates are presented in
Tables 5-5 and 5-6 for Po-210 and Pb-210, respectively. The reductions
from baseline are presented in Tables 5-7 and 5-8. Both of these control
alternatives achieve a significant reduction in emissions beyond those
that are estimated for venturi scrubbers and wet ESP's.
5.3 COSTS OF CONTROL ALTERNATIVES

Capital and annualized costs for each of the 10 control alternatives
evaluated were developed using the procedures described in Section 4.3.
Nationwide and plant specific capital and annualized cost summaries for
each control alternative are presented in Tables 5-9 and 5-10, respec-
tively. Nationwide capital and annualized costs for the 10 control
alternatives are compared graphically in Figures 5-1 and 5-2. A more
detailed breakdown of costs for each alternative is presented in
Tables 5-11 through 5-20. Details on the cost inputs for the venturi
scrubber, wet wall ESP, SD/FF, and HEPA filter system for each facility
are presented in Appendices A through E.


ao,
o
oom

o
Qa
ow

°
-
Ly

where:

Yot
L/G

where:
B
L/G
A.
°g
Cp

where:
Koo
dp
Yot
Yg
dq

venturi throat length, cm

drag coefficient for the liquid at the throat entrance,
dimensionless

gas density, g/cm?

droplet diameter, cm

liquid density, g/cm”

Dy = (GM y+91.8 (Lvs) °° (Eq. 4-11)
gt
= droplet diameter, cm
= gas velocity in the throat, cm/s
= liquid-to gas ratio, dimensionless
9,
B = (L/G) acy (Eq. 4-12)
g

= parameter characterizing liquid-to-gas ratio, dimensionless
liquid-to-gas ratio, dimensionless

= liquid density, g/cm”

gas density, g/cm?

drag coefficient for the liquid at the throat entrance,
dimensionless

dv

t
Koo 7 Tig. (Eq. 4-13)

inertial parameter at the throat entrance, dimensionless
particle aerodynamic resistance diameter, cmA

= gas velocity in the throat, cm/s

= gas viscosity, g/cm * s

droplet diameter, cm

v
= 2 t
Koo = gf q (Eq. 4-14)

u


100° 0> 100°0> 100°0> T00°0> 100°0> 4aqLts Wd3H

200°0 100°0 z10°0 STO £b0°0 JIILLJ Dages/4sakup Keads
10° 0> 10°0> z0°0 62°0 bro {ea} 8ST = VIS
10°0 10°0 20°0 bs" 8€°0 1 (S/H) BIT = v9S
20°0 20°0 61°0 2 at Rt 8°8L = VIS
80°0 40°0 65°0 bel 6°2 ,- (S/W) b°6E = WOS

dS3
9T0°0 v1o"0 21°0 ST o'r P44 OZ = dV
T€0°0 820°0 b2°0 ore 0°2 edt OT = av
bT°o €T'0 Ut br O'b Pd¥ 2°9 = dV
22°0 02°0 S°T lz 0°8 ed4 G°2 = dV

Aaqqnsss 33K

Lequap1990 dassauual Bue jUOW OJUPSUOW oWd BAL QPUsTZLe [O4qUOD

EEFPULEYS

AK7( 9 *S[aaal uopsspwy

S3AILUNYILTY TOMLNOD AM G3IAFTHIW S13AF1 NOISSIW] OTZ-Od G3LWWILSI

°G-G FAVE

5-10


emissions), and properly conditions the stream for treatment by the other
options.

Capital costs include the direct and indirect costs to purchase and
install the necessary ductwork, control device, fan systems, and stack.
Direct capital costs include instruments, controls, taxes, freight,
foundations, supports, erection and handling, electrical work, piping,
insulation, painting, and site preparation. Indirect capital costs
include engineering and supervision, construction and field expenses,
construction fee, startup performance test, and contingencies. Table 4-4
presents the assumptions used for direct and indirect cost estimates based
on information given in the GARD manual. A11 ductwork was sized based on
a gas velocity of 20 meters per second (m/s) (4,000 ft/min). Site-
specific estimates of the length of additional ductwork to connect the
existing control system with the add-on control device were developed for
the analyses in Section 5. Stack diameters were calculated to provide a
stack gas velocity of 18 m/s (3,600 ft/min). All stack heights are
assumed to be 15 m (50 ft) for the add-on equipment. With the exception
of connecting ductwork, no special retrofit costs were included in the
cost analyses. Based on information collected during plant visits, no
retrofit problems are expected at these facilities.

Annualized costs include the total utility costs, the total operating
labor costs, the total maintenance costs, the total overhead costs, the
capital charges, and the total waste disposal costs. The annualized costs
were based on 8,640 hours per year of operation (360 days). The utility
costs reflect actual utility costs in the area of each facility as
presented in Appendices A through E. The operating and maintenance labor
costs were determined using an average hourly wage of $12/hour (h). The
operating labor hours per shift for each control device were 4 h/shift for
SD/FF's, 2 h/shift for scrubbers, and 1 h/shift for ESP's. The main-
tenance labor was assumed to be 1 h/shift for ESP's and scrubbers and
2 h/shift for SO/FF's.

The quantity of sludge or dry waste collected by the add-on control
devices was determined based on the efficiency of particulate removal. In
the case of the SD/FF, the quantity of lime added to the system also is
considered. The cost to dispose of the waste in a secured landfill was

4-42


elemental phosphorus plants is a movable throat venturi. The other is a
fixed-throat, tandem-nozzle unit.

Venturis are the scrubbers used most commonly at elemental phosphorous
plants and are capable of achieving the high particle collection effi-
ciency. As the exhaust stream enters the throat, its velocity increases
greatly, resulting in droplet atomization and turbulent mixing of the gas
with any liquid present. Particulate matter in the gas is collected in
these droplets, primarily by impaction. These liquid droplets then are
removed from the scrubber exhaust stream by cyclonic separators or chevron-
blade mist eliminators.

Particle removal efficiency increases with increasing pressure drop
(resulting in high gas velocity and turbulence.) Venturis can be operated
with pressure drops ranging from 1 to 25 kPa (5 to 100 in. w.c.). Venturi
scrubbers that operate with pressure drops of less than 12.5 kPa (50 in.
w.c.) have been installed on nodu lizing kilns. At these pressure drops,
the gas velocity in the throat section is usually between 30 and 120 m/s
(100 and 400 ft/s). An increase in pressure drop increases operating
costs because of the energy required by the fan to remove the large air
volumes from the kilns at higher static pressures. It also increases
capital cost because thicker construction materials are required to handle
the lower static pressures in the ductwork.

The liquid injection rate, or L/G ratio, also affects particle
collection. The L/G ratio depends on the temperature (evaporation losses)
of the incoming exhaust stream and the particle concentration. Most
venturi systems operate with an L/G ratio of 0.4 to 1.3 a/m° (3 to
10 gal/1,000 ft’). Liquid-to-gas ratios less than 0.4 a/m?

(3 ga1/1,000 ft’) are usually not sufficient to cover the throat, and add-
ing more than 1.3 2/m (10 ga1/1,000 ft’) does not usually significantly
improve particle collection efficiency. | The two operating venturi
scrubbers in the elemental phosphorus industry have L/G ratios of about
0.8 2/m> (6 gal/1,000 ft’) and 2.4 /m? (18 gal/1,000 ft”).

4.1.3 Wet ESP's

Electrostatic precipitators are high-efficiency PM collection devices
that have been applied widely to a variety of combustion sources and
metallurgical furnaces that have a wide range of combustion gas

4-10


4.1.2 Venturi Scrubbers

A venturi scrubber is a high-efficiency PM control device that
enhances particle collection by generating high-velocity, turbulent flow
conditions in the gas stream. A venturi scrubber consists of three
sections--a converging section, a throat section, and a diverging section
as shown in Figure 4-2.' The exhaust stream enters the converging
section, and gas velocity and turbulence increase. Liquid is introduced
either at the throat or at the entrance to the converging section. In the
throat, the gas stream is mixed with the droplets that are sheared from
the walls, and gaseous and particulate pollutants are transferred from the
gas stream to these droplets. The exhaust stream then exits through the
diverging section. Venturis can be used to collect both particulate and
gaseous pollutants, but they are more effective in removing particles than
in removing gaseous pollutants.

Liquid can be injected at the converging section or at the throat.
Figure 4-3 shows liquid injected at the converging section. Because this
type of venturi provides a liquid coat on the throat surface, it is very
effective for handling hot, dry exhaust gases that contain dusts that tend
to cake on or abrade a dry throat. Generally, this wet throat approach is
more appropriate for application to elemental phosphorus kiln or calciner
operations for two reasons. First, because the gas stream contains high
concentrations of HF and S0,, the wetting/drying phenomena that occurs at
the throat in dry throat applications can result in increased corrosion.
Second, the PM in these exhaust streams has a tendency to scale, and this
scaling is enhanced in a dry throat. Consequently, the wetted throat has
fewer operation and maintenance problems and achieves better long-term
performance than the dry throat.

Manufacturers have developed modifications to the basic venturi
design to maintain scrubber efficiency by changing the préssure drop for
varying exhaust gas rates. One particular development is the annular-
orifice, or adjustable-throat, venturi scrubber (Figure 4-4). The throat
area is varied by moving a plunger, or adjustable disk, up or down in the
throat, decreasing or increasing the annular opening. Gas flows through
the annular opening and atomizes liquid that is sprayed onto the plunger
or swirled in from the top. One of the two venturi scrubbers installed at

4-6


electric arc. At the heat source, the maximum temperature can reach
4400°C (7950°F). At 1400° to 1800°C (2550° to 3270°F), silica becomes a
strong acid that reacts with the calcium phosphate to yield a calcium
silicate slag and P,0;. The P.0; in turn reacts with the carbon in the
coke and is reduced to CO and Pp.”

The elemental phosphorus is driven off as a vapor in the CO off-gas
stream. The slag and ferrophosphorus continually collect in the bottom of
the furnace in molten layers with the denser ferrophosphorus layer below
the slag layer. Periodically, these molten by-products are tapped
separately. Slag is tapped approximately once each hour and
ferrophosphorus up to several times each day. The slag and
ferrophosphorus are air cooled in a pit and stockpiled for later use.

At three of the five facilities, the furnace product gases are
treated for dust removal in an electrostatic precipitator (ESP). At the
other two facilities, the gas stream is routed directly to the phosphorus
recovery processes. The gas stream from the ESP, or from the furnace at
those plants that do not have an ESP, are sent to water spray condensers
where the gases are cooled and the phosphorus {fs condensed to a liquid.
The condensed phosphorus is collected under water, purified by filtering,
and then pumped to underwater storage. The gas stream from the condenser
is primarily CO. Essentially all of the phosphorus-free CO is recycled to
fuel the nodulization process. The remaining CO is recycled to other
plant operations or exhausted through flare stacks. Plant personnel
indicated that CO is flared only on days when the kiln is not operating.
2.2.2 Radionuclide Distributions

The primary objective of this study is to evaluate Po-210 and Pb-210
emissions from elemental phosphorus plants (particularly from the
nodulizing kiln or calciner) and to develop alternatives for the control
of these emissions. Consequently, the distribution of Po-210 and Pb-210
among the different process streams is of interest. The paragraphs below
summarize the information that has been collected on these distribu-
tions. This information is based on comprehensive studies of elemental
phosphorus production conducted for EPA prior to 1983, test data developed
by EPA in 1983 and 1984, and data supplied by the plants during earlier
EPA studies and during site visits conducted for this study.



3.4
1.

2.

4,

5.

6.
7.

8.

lo.

ll.

REFERENCES FOR SECTION 3

Eadie, G. and Bernhardt, D. Radiological Survey of Idaho Ore
Processing--The Thermal Process Plant. Prepared for U. S.
Environmental Protection Agency. Las Vegas, Nevada. Technical Note,
ORP/LV-77-3. November 1977.

Andrews, V. Emissions of Naturally Occurring Radioactivity from
Monsanto Elemental Phosphorus Plant. Prepared for U. S. Environ-
mental Protection Agency. Las Vegas, Nevada. Publication

No. EPA-520/6-82-021. November 1982.

Andrews, V. Emissions of Naturally Occurring Radioactivity from
Stauffer Elemental Phosphorus Plant. Prepared for U. S. Environ-
mental Protection Agency. Las Vegas, Nevada. Publication

No. EPA-520/6-82-019. November 1982.

Weast, R. C., ed. CRC Handbook of Chemistry and Physics, 64th
Edition. Cleveland. The Chemical Rubber Company. 1984.
p. 0-196.

Brooks, L. S. The Vapor Pressure of Polonium. Journal of the
American Chemical Society. 77:3211. 1955.

U. S. Environmental Protection Agency. fmissions of Lead-210 and
Polonium-210 from Calciners at Elemental Phosphorus Plants: FMC
Plant, Pocatello, Idaho. Washington, D.C. June 1984.

U. S. Environmental Protection Agency. Emissions of Lead-210 and
Polonium-210 from Calciners at Elemental Phosphorus Plants: Monsanto
Plant, Soda Springs, Idaho. Washington, D.C. September 1984.

U. S. Environmental Protection Agency. Emissions of Lead-210 and
Polonium-210 from Calciners at Elemental Phosphorus Plants: Stauffer
Plant, Silver Bow, Montana. Washington, 0.C. U. S. EPA.

August 1984.

Stula, R. T., R. E. Balanger, C. L. Clary, R. F. May, M. E. Spaeth,
and J. P. Swenson. Airborne Emission Control Technology for the
Elemental Phosphorus Industry, Final Report for EPA Contract

No. 68-01-6429. Science Applications, Inc. La Jolla, California.
January 1984.

Memo and attachments from Leeds, K., Midwest Research Institute, to
Beck, L., EPA/ISB. October 14, 1988. State Emissions Standards for
Elemental Phosphorus Plants.

Cowherd, C., G. Muleski, and J. Kinsey. Control of Open Fugitive Dust
Sources. Prepared for U. S. Environmental Protection Agency. Research
Triangle Park, North Carolina. Publication No. EPA-450/3-88-008.
September 1988.

3-23


4. EMISSION CONTROLS

The nodulizing kiln or calciner is by far the most significant source
of Po-210 and Pb-210 emissions from elemental phosphorus production. This
section describes and assesses control technologies that can be used to
reduce those emissions. Generally Po-210 and Pb-210 are volatilized in
the kiln or calciner and preferentially condense on the fine particles in
the calciner PM emission stream. The control systems that are installed
in the industry effectively collect large particles, but they are not
effective controlling fine particle emissions. Consequently, the technol-
ogies examined in this section are those that have been demonstrated to
achieve high control efficiencies on fine particles. However, control of
Po-210 and Pb-210 emissions is complicated by two factors. First, because
the temperature of the flue gas leaving the kiln may be 400°C (750°F) or
higher, significant concentrations of Po-210 can remain in the vapor phase
(see Figure 3-1). Second, the exhaust contains relatively high concentra-
tions of SO, and HF; these acid gases can condense in the control system
leading to subsequent corrosion and deterioration of performance.
Mechanisms for cooling the exhaust gases and reducing the acid gas concen-
tration in the gases are discussed later in this section.

Applicable control systems for the kiln or calciner emissions are
examined in the three subsections below. The first describes the control
systems; discusses the operating principles of each system; and identifies
key design and operating parameters which affect performance, as measured
by Po-210 and Pb-210 reduction, and costs. The second describes proce-
dures for estimating the performance of each type of control system and
discusses the emission data that are available on system performance. The -
third describes the general procedures for estimating the costs for each
control system and presents assumptions used to develop estimates for :
major cost elements for each of the control systems. Details of specific
control alternatives and the performance and cost of those alternatives
are contained in Section 5.


evaluated on a plant-by-plant basis in Section 5.0. In general, these
procedures are based on estimates of overall PM control efficiencies or
particle-size-specific control efficiencies. The Po-210 and Pb-210
efficiencies then can be estimated on the basis of the Po-210 or Pb-210
concentrations in the PM or in specific size fractions. To the degree
that emission data are available, the validity of the estimating
procedures was evaluated by comparing estimated efficiencies to measured
control efficiencies. Each of the four control techniques is addressed in
individual subsections below.
4.2.1 Venturi Scrubbers

The control efficiency of venturi scrubbers is highly dependent on
particle size distribution and on the L/G ratio and pressure drop across
the scrubber. The penetration across a venturi scrubber (where penetra-
tion is 1 minus control efficiency) for a particle of specific diameter
can be estimated by the following equations which was developed by Yung
and Calvert.‘ The equations presented below are used to develop
performance estimates for venturi scrubber control options in Section 5.

o.s
4 kgt4.2-5.02 Kyo? 8 (egz)tan” we fa. 410
In Pt(d,) = -8 ma (Eq. 4-10)
po
where:
Pt(d,) = penetration for one particle size

B = parameter characterizing the liquid-to-gas ratio,
dimensionless
Kho = inertial parameter at throat entrance, dimensionless

Note: Equation 4-9 was developed assuming that the venturi has an
infinite-sized throat length. This is valid only when 2, as defined
below, is greater than 2.0.
1: 32,Cpe,
204°.

(Eq. 4-10)

where:
&% = throat length parameter, dimensionless

4-30


TABLE 2-3. OPERATING ELEMENTAL PHOSPHORUS PLANTS, 1988

—— _ - SS - a —

Phosphorus Ore
capacity, requirements,
1g” Mg/yr 19° Mg/yr
Plant (10° tons/yr) (10° tons/yr)
FMC Corporation, Pocatello, Idaho 123 (135) 1,470 (1,620)
Monsanto Co., Soda Springs, Idaho. 95 (105) 1,000 (1,100)
Stauffer Chemical Co., Silver Bow, 38 (42) 380 (420)
Mont.
Stauffer Chemical Co., Mt. Pleasant, 41 (45) 440 (480)
Tenn.
Occidental Chemical Co., Columbia, 45 (50) 490 (540)
Tenn.

—— ——e — —— — ——

2-6


molecules (pollutant) arrive at the interface area. In the third step,
the gas diffuses into the bulk area of the liquid, thus making room for
additional gas molecules to be absorbed. The rate of absorption (mass
transfer of the pollutant from the gas phase to the liquid phase) depends
on the diffusion rates of the pollutant in the gas phase (first step) and
in the liquid phase (third step). For HF, which is highly soluble, the
rate is gas-phase controlled. For the less soluble SO,, the rate is
liquid-phase controlled and depends on the reaction rate of SO, with lime
to form calcium sulfate.

The following design factors enhance gas diffusion, and, therefore,
absorption:

1. Large interfacial contact area between the gas and liquid phases;

2. Good mixing of the gas and liquid phases (turbulence); and

3. Sufficient residence or contact time between the phases for
absorption to occur.

An important factor affecting the amount of a pollutant that can be
absorbed is its solubility. Solubility governs the amount of liquid (L/G
ratio) required and the necessary contact time. More soluble gases (such
as HF) require less liquid. Also, more soluble gases will be absorbed
faster. Solubility is a function of temperature. As temperature
increases, the amount of gas that can be absorbed by a liquid decreases.
The solubility and gas scrubbing efficiency also are affected by the pH of
the scrubbing liquor. Plant personnel indicate that for SO,, efficiency
increases monotonically with the pH of the scrubbing liquor (i.e., an
increase of pH will increase scrubber efficiency). However, for HF, the
optimal scrubbing efficiency is achieved at a pH of about 7.5 to 8.0, and
higher pH levels result in significant decreases in efficiency. The pH in
the spray towers at the elemental phosphorus plants in Tennessee generally
is maintained in the range of 7.5 to 8.0.° Personnel at the western
elemental phosphorus plants indicated that the characteristics of their PM
and water necessitate maintenance of pH in the range of 4.5 to 5.0 to
inhibit precipitation and scaling in the scrubbing system.”

4-5


ane

TABLE OF CONTENTS

LIST OF FIGURES..........-eeeeeeee sce ceeecececccccsccscecesesesesese IV
LIST OF TABLES........ceeeeeeeeees seen eee cesecececcecececesescsesees V

SECTION 1.0
SECTION 2.0

SECTION 3.0

SECTION 4.0

SECTION 5.0

1

INTRODUCTION... ..0scececcccccacccccccecesesccsscecs eee

ELEMENTAL PHOSPHORUS INDUSTRY DESCRIPTION.....-..seeeee
2.1 INDUSTRY CHARACTERIZATI'

2.2 SLEMENTAL PHOSPHORUS PRODUCTION” PROCESSE

2.2.1 Process Description.......

2.2.2 Radionuclide Distributions

2.3 REFERENCES FOR SECTION 2.........

EMISSIONS FROM ELEMENTAL PHOSPHORUS PLANTS......-2eee- .
3.1 URCES OF RADIONUCLIDE EMISSIONS..........06. sees
3.2 ILN EMISSION CHARACTERIZATION. .....ceseceececeees
3.2.1 Mass Emission Rates of Po-210, Pb-210

ANd PM... cece ec ec cece ccc ccccccccccceeees
3.2.2 Acid Gas EmisSions.......sseceesseeeeseeeee
3.2.3 Po-210 and Pb-210 Particle Size

Distributions......cceccecccccscccceccees
KILN BASELINE EMISSIONS......... eee
REFERENCES FOR SECTION 3........--e00

SSION CONTROLS....
SCRIPTION OF APPLICABLE CONTROL §

tora ree
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Yew WH WoO Nrommnn re

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1.1) Spray Towers.......s.cceeeeeee

1.2 Venturi Scrubbers.....

1.3 Wet ESP's......

1.4 SD/FF Systems..

1.5 HEPA Filters..

RFORMANCE OF ALTERNATIVE CONTROL FECHWOLOGIES. «-
3. «l Venturi Scrubbers............ oe ceccccecces
2.
2
S
3
3

PPesseoana

2 Wet ESP'S... ccc ceeeccececeeee
-2.3 SD/FF Systems...
+2.4 HEPA Filters..........eceeee
OST OF CONTROL TECHNOLOGIES.........

-l Venturi Scrubber Cost Assumpti
«2 Wet ESP Cost Assumptions........
3.3 SD/FF Cost Assumptions......
4.3.4 HEPA Filter Cost Assumptions

4.4 REFERENCES FOR SECTION 4...

CONTROL ALTERNATIVE PERFORMANCE AND cosT. seceeeeececese Sal

I

il

4

4.

4

4.

4
4.2 PI
4,

4,

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5.1 DEFINITION OF CONTROL ALTERNATIVES......cececeeees §-1
5.2 PERFORMANCE OF CONTROL ALTERNATIVES.... «+ 5-3
5.3 COSTS OF CONTROL ALTERNATIVES...... rerrererr reer 5-12

5.4 REFERENCES FOR SECTION 5......ececeeeeee seeceseeee 5-29

APPENDICES A-E: SEPARATE CBI VOLUME

iii


Most pulse jet filters use bag tubes that are 10 to 15 cm (4 to
6 in.) in diameter. Typically, the bags are 3.0 to 3.7 m (10 to 12 ft)
long, but they can be as long as 7.6 m (25 ft).? Generally, these bags
are arranged in rows, and the bags are cleaned one row at a time in
sequence. Cleaning can be initiated by a pressure drop switch, or it may
occur on a timed sequence.

The key design and operating parameters for a SD/FF are the air-to-
cloth ratio (or the filtration velocity), the bag material, operating
temperature in the filter, operating pressure drop across the filter, and
the lime usage rate in the spray dryer.

The air-to-cloth ratio is actually a measure of the superficial gas
velocity through the filter medium. It is a ratio of the flow rate of gas
through the fabric filter (at actual conditions) to the area of the bags
and is usually measured in units of m/min of cloth area (acfm/ft?). No
operating data are available for elemental phosphorus systems, but
generally, the air-to-cloth ratio on SO/FF systems is in the range of 1.5
to 3 m°/min/m (5 to 10 acfm/ft *) of bag area.'

Bag material selection generally is based on prior experience of the
vendor. Key factors that. generally are considered are: cleaning method,
abrasiveness of the particulate matter and abrasion resistance of the
material, expected operating temperature, potential chemical degradation
problems, and cost. No information was obtained on types of material
typically used for metallurgical applications. However, given the
temperature and acid gas concentrations in the nodulizing kiln exhaust
gases, some type of teflon-coated synthetic material is likely to be the
material of choice.

The operating temperature of the fabric filter is of critical
importance. Since the exhaust gas from nodulizing kilns or calciners can
contain HF and SO,, the unit should be operated at sufficiently high
temperatures to ensure that no surface temperatures drop below the acid
dewpoint. Otherwise, condensation of acid gases will result in corrosion
of the housing or bags. Gas temperatures maintained at about 150°C
(300°F) ensure that no surfaces are cooled below the dewpoint. At the
same time, temperatures should be as low as possible to ensure complete
condensation of Po-210. Above a maximum temperature that is dependent on

4-22


information on calciner emission rates is presented in Section 3.2. No
additional data on emissions from sources other than the calciner were
identified during this study.

The principal source of Po-210 and Pb-210 emissions from elemental
phosphorus production is the nodulizing kiln or calciner. Emissions from
the calciner are generated via three mechanisms. First, both Po-210 and
Pb-210 are relatively volatile metals as evidenced by the vapor pressure
curves shown in Figure 3-1.°** The horizontal axis of the curve indicates
temperature and the vertical axis indicates the partial pressure of the
Pb-210 and Po-210 at temperature. The maximum concentration that the
metal can achieve in vapor phase is the ratio of the partial pressure to
760 mmHg. At the temperatures reached in the calciner/kiln ore bed
(~1300°C), significant quantities of Po-210 and Pb-210 are volatilized and
exit the kiln as vapor in the combustion gas stream. These vapor-phase
metals generally condense on surfaces of PM that is entrained in the
combustion gas before they penetrate the air pollution control system.
Second, as the combustion gases are drawn through the ore bed of the
moving grate-calciner or the tumbling ore in a kiln, relatively large
quantities of PM are entrained in the combustion gas stream. These
entrained particles, which contain Po-210 and Pb-210, also are exhausted
from the calciner with the combustion gases. Third, Po-210 and Pb-210 can
be volatilized in the electric furnace and returned to the kiln in the CO
fuel stream. The Po-210 and Pb-210 again will leave the kiln as vapor and
condense on PM surfaces downstream from the kiln.

Data on the relative concentrations of Po-210 and Pb-210 in the ore
feed and nodule product were collected by EPA at three facilities. °~°
These data indicate that on a mass basis assuming the nodule mass flux is
about 80 percent of the ore mass flux, less than 10 percent of the Po-210
and 20 to 60 percent of the Pb-210 are retained in the nodules for rotary
kiln operations. For the moving grate calciner, about 30 percent of the
Po-210 and almost al] of the Pb-210 remain in the nodules. These losses
represent the quantity of material lost to the calciner/kiln combustion
gases via the first two mechanisms. No data on the quantity of Po-210 and
Pb-210 that return to the calciner/kiln with the CO were identified during
this study. However, the quantities are expected to be relatively small

3-3


thereby precluded from contacting downstream surfaces as a wet powder
leading to solids buildup. The system also is operated well above the
dewpoints of any acid gases. Temperatures are typically controlled at
110° to 160°C (230° to 320°F) by limiting the amount of water injected. *°

The particulate matter that leaves the spray dryer must be controlled
by a high-efficiency PM collector. The control device typically employed
on metallurgical furnaces is a fabric filter. Generally, fabric filters
are classified by the type of cleaning mechanism that is used to remove
the dust from the bags. The three types of units are mechanical shakers,
reverse air, and pulse jet. Essentially all fabric filters that are
employed with spray dryers are pulse jet units. The paragraphs below
briefly describe the design and operating characteristics of pulse jet
filters and identify key design parameters for SD/FF systems.

A schematic of a pulse jet filter is shown in Figure 4-9. Bags in
the baghouse compartment are supported internally by rings or cages. Bags
are held firmly in place at the top by clasps and have an enclosed bottom
(usually a metal cap). Dust-laden gas is filtered through the bag,
depositing dust on the outside surface of the bag. Pulse jet cleaning is
used for cleaning bags in an exterior filtration system.

The dust cake is removed from the bag by a blast of compressed air
injected into the top of the bag tube. The blast of high pressure air
stops the normal flow of air through the filter. The air blast develops
into a standing or shock wave that causes the bag to flex or expand as the
shock wave travels down the bag tube. As the bag flexes, the cake
fractures and deposited particles are discharged from the bag. The shock
wave travels down and back up the tube in approximately 0.5 seconds.*?

The blast of compressed air must be strong enough for the shack wave
to travel the length of the bag and shatter or crack the dust cake. Pulse
jet units use air supplied from a common header which feeds into a nozzle
located above each bag. In most baghouse designs, a venturi sealed at the
top of each bag is used to create a large enough pulse to travel down and
up the bag. The pressures involved are commonly between 414 kPa and
689 kPa (60 and 100 psig). The importance of the venturi is being
questioned by some pulse jet baghouse vendors. Some baghouses operate
with only the compressed air manifold above each bag."

4-20


The major differences in the types of wet ESP's are the shape of the
collector, whether treatment of the gas stream is vertical or horizontal,
whether incoming gas is preconditioned with water sprays, and whether the
entire ESP is operated wet. Figures 4-6 and 4-7 show two types of wet
ESP's, the circular-plate variety and the square or rectangular flat-plate
type. One wet ESP currently is installed on one nodulizing kiln. The ESP
is a circular-plate type with a spray tower upstream of the ESP to
condition the gas stream. Plant personnel indicated that when the ESP
reaches the end of its useful life, they probably will install a flat-
plate system because it is easier to maintain than the circular-plate
unit.

The casing can be constructed of steel or FRP, and discharge
electrodes can be carbon steel, special alloys, or FRP, depending on the
corrosiveness of the gas stream. The system that presently is in use has
FRP plates, but plant personnel indicated that these plates have not
lasted well in the cold winter environment in Montana. However, because
the kiln exhaust is corrosive and liquid pH must be maintained at 5 or
Tess, the plates must be constructed of FRP or corrosion-resistant alloys.

In circular-plate wet ESP's, the circular plates are irrigated
continuously; this continuous flow provides the electrical ground for
attracting the particles and also removes them from the plate. These
systems can generally handle flow rates of 850 to 2,800 m/min (30,000 to
100,000 ft?/min). Preconditioning sprays remove a significant amount of
particulate by impaction. Pressure drop through these units usually
ranges from 0.25 to 0.75 kPa (1 to 3 in. wec.)e?

Rectangular flat-plate units operate in basically the same manner as
the circular-plate wet ESP's. Water sprays in an inlet plenum or in an
upstream spray tower precondition the incoming gas and provide some
initial particulate removal. The water sprays are located over the top of
the electrostatic fields, and collection plates are irrigated continu-
ously. The collected particulate flows downward into a trough that is
sloped to a drain. Typically the water is treated onsite to remove the
suspended solids, and treated water is recycled to the system. Plant
personnel indicated that the water for the ESP currently operating at an
elemental phosphorous facility is treated to a pH of about 5 to prevent
scaling on the plates.”

4-13


TABLE 2-4. Po-210 CONCENTRATIONS IN ELEMENTAL PHOSPHORUS PROCESS STREAMS

— ——_ —
Po-210 concentrations, pCi/g_
FMC, Monsanto, Stauffer Occidental, Monsanto,
Process stream Idaho tdaho Font Tenn Tenn. Tenn.
Ore 228 oie 36° 3.5¢ 4.1e af
219 126 40'
23)
23
Nodules «2.68 1.9? ai 0.09! 3.3f
8
9.84
Slag <164 <% (fresh) 0.44 <o.8f
2.7% (piled)
Ferrophesphorus <0.6? <1.9¢ 0.054 tof
Intet PM 2,5009 1,920" 3,400! ,
2
4)
Stack PM 19,0009  37,000° 37,000! 1,200°
25,000" 5,000?
53,000 35,000!

—- _ _
Based on EPA test data collected in 1977 as presented in Reference 4.
sed on EPA test data collected in 1984 as presented in Reference 5; includes combined ore
and recycle feed,
SQased on EPA test data collected in 1982 as presented In Reference 6. -
‘Based on data suppiied to EPA by facility as presented in Reference 2.
‘Data presented in Reference 2. Concentrations assumed to be equal to those measured at the
Monsanto, Tennessee, facility in 1982 as presented in Reference 7.
Based on EPA test data collected in 1982 as presented in Reference 7.
Seased on test data collected by EPA in 1984 as presented in Reference 8.
{Based on EPA test data collected in 1988 as presen in Reference 9,
‘Based on test data collected by EPA in 1984 as presented in Reference 10.
JBased on data supplied to MRI by facility during 1988 site visit and reported in
Reference 11. Nodule estimates based on average of three measurements made through bed;
values ranged from 5.8 to 14.9.
‘Based on EPA test data collected in 1988 as presented in Reference 12.
Based on data supplied to MRI by facility during 1988 plant visit as reported in
Reference 13.
"Based on emission test data collected by the facility in 1985 through 1987 as reported in
Reference 11.
"Based on emission test data collected by the facility in 1988 as reported in Reference 14.
jased on data supplied to MRI by the facility during 1988 plant visit as reported in
Reference 15.

2-12


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Summary of Po-210 emission data.
3-13

Low-Energy Scrubber

Figure 3-2.

No Control


section

Figure 4-2. Venturi scrubber. '

4-7


12.

13.

14.

15.

16.

Radian Corporation. Draft Final Emission Test Report, FMC Elemental
Phosphorus Plant, Pocatello, Idaho. Prepared for U. S. Environmental
Protection Agency under Contract No. 68-02-4338. Research Triangle
Park, North Carolina. October 1988.

Memo and attachments from Wallace, D., and J. Obremski, Midwest
Research Institute, to Beck, L., EPA/ISB. August 23, 1988. Site
Visit--Stauffer Elemental Phosphorus Plant, Mount Pleasant,
Tennessee.

Memo and attachments from Wallace D., and K. Leeds, Midwest Research
Institute, to Beck, L., EPA/ISB. August 9, 1988. Site Visit--
Monsanto Elemental Phosphorus Plant, Soda Springs, Idaho.

Memo and attachments from Wallace, D., and J. Obremski, Midwest
Research Institute, to Beck, L., EPA/ISB. August 23, 1988. Site
Visit--Occidental Elemental Phosphorus Plant, Columbia, Tennessee.

Telecon. Wallace, D., Midwest Research Institute, with Abbot, D.,

Monsanto Chemical Company. July 12, 1988. Radionuclides in
Phosphorus Process Streams.

2-15


application, pulse jet collection efficiency is reported to be a function
of inlet concentration, filtration velocity, pulse intensity, pulse
duration, and pulse form.'® Test data generally show that for a specific
process with fabric filter operating parameters held at steady conditions,
the outlet concentration of a pulse jet filter remains relatively
constant. Under such conditions, the efficiency of the fabric filter is
primarily a function of the total inlet concentration.

The findings described above suggest a procedure for estimating
Po-210 and Pb-210 removal efficiencies for OS/FF systems based on the
following assumptions:

1. The PM removal efficiency of a pulse jet fabric filter is not
particle-size dependent; -

2. At the temperatures achieved in a SD/FF system, essentially all
Pb-210 and Po-210 is in particle form. Consequently, Po-210 and Pb-210
are removed by the fabric filter at the same efficiency as total PM;

3. Pulse jet fabric filters associated with SD/FF systems have been
shown to achieve outlet PM concentrations in the range of 22 mg/dscm
(0.01 gr/dscf) to below 2.2 mg/dscm (0.001 gr/dscf).'°*'® An outlet
concentration of 22 mg/dscm (0.01 gr/dscf) will provide a conservative
estimate of achievable PM control efficiency; and

4. The PM concentration at the inlet to the fabric filter is a
combination of the solvent/acid gas reaction products and the PM emitted
from the kiln.

Under the assumptions described above, the Po-210 and Pb-210 contro]
efficiencies can be estimated as follows:

Inlet PM concentration-Outlet PM concentration
Inlet PM concentration

Efficiency =

Obviously, no data are available to validate this procedure for nodulizing
kilns or calciners. However, estimates of the efficiency were developed
for a "model facility" under the following set of assumptions which are
based on "typical" levels reported by elemental phosphorus facilities.

SO, concentration 1,200 ppmv
HF concentration 600 ppmv
PM concentration 4,000 mg/dscm

4-40


TABLE 3-8. PARTICLE SIZE DATA BASED ON SAS.

———

S CYCLONE SAMPLES

—

Percentage of pollutant
in size range

Approximate particle

size 0-50, um

Poltutant Facility Location <1 1-3 3-10 >10

Po-210 Stauffer Spray tower 72.2 9.6 0.4 17.8
outlet

ESP outlet 91.2 0.3 0.1 8.4

Monsanto Stack 94.6 3.7 0.5 1.2

Pb-210 Stauffer Spray tower 92.4 4.0 0.2 3.4
outlet

ESP outlet 96.9 1.1 0.1 1.9

Monsanto Stack 93.7 4.3 0.6 1.4

3-20


analyses because the particle size was measured in the ductwork between
the spray tower and the venturi. This high moisture stream from the spray
tower is difficult to sample, and the inherent difficulties associated
with particle size sampling in the high moisture exhaust stream can result
in significant measurement errors. If the actual particle size at the
venturi inlet is different than that assumed for the calculation, the
model will produce biased results.

Second, the measurements of PM particle size at the venturi inlet and
outlet indicate that the efficiency of the venturi is uniform overall
particle size ranges. In light of the strong dependency of venturi
scrubber performance on particle size suggested by the performance model
and generally supported by other venturi scrubber test data, this finding
is quite surprising. The estimated efficiency of 95 percent or greater in
particles less than 0.5 um in size is particularly surprising. Conse-
quently, the measured efficiency may be biased high and should be used
with caution.

In light the differences in the predicted and measured results at
Monsanto, analyses based on a combination of measured performance at
Monsanto and FMC and estimated performance based on the Yung/Calvert model
were selected for estimating venturi scrubber performance. The estimated
performance of the Monsanto and FMC is scrubbers presented in Table 4-2.
The model is well established in the technical literature and generally is
used by vendors for scrubber design. Because the analysis are somewhat
uncertain the results presented in Section 5 should be interpreted with
caution because they are highly sensitive to particle size distribution
and measurement limitations.

4.2.2 Wet ESP's

For applications of ESP's to a specific type of industrial process
such as elemental phosphorus nodulizing kilns or calciners, the primary
design factor that affects ESP performance is the SCA, which is a ratio of
the collection plate area to the volumetric flow through the ESP. This
relationship is incorporated in the Deutsch-Anderson equation for estimat-
ing ESP efficiency:

n = l-exp [-w(A/Q)] (Eq. 4-20)

4-35


DISCHARGE ELECTRODE
AT NEGATIVE POLARITY

CHARGED
PARTICLE

ELECTRICAL
FIELD

EARTHED COLLECTOR
ELECTRODE AT
POSITIVE POLARITY
CURRENT SUPPLY

Vartcuts ATTRACTED
TO COLLECTOR ELECTRODE

AND FORMING DUST LAYER

UNCHARGED
PARTICLES
Illustration of ESP operating principles.°®

4-12

Figure 4-5,


TABLE 4-2. ESTIMATES OF VENTURI SCRUBBER PERFORMANCE

ee — —

Pressure Po-210 Pb-210 Efficienc
Facility drop Inlet Outlet Inlet Outlet Po-210  Pb-210

Monsanto* High 4,052 172 1,280 40.58 96 97
Fucb Maximum® 1,075 1,065 43.6 26.1 Neg. . 40
Typical? 1,075 1,208 43.6 4.1 Neg. 91

pReference 13.

Reference 14.

‘Adjustable low-energy throat venturi scrubber operated at system maximum
AP.

dadjustable throat low-energy venturi scrubber operated at typical
operating aP.

4-36


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5-27


The final processing step that is a potential source of Po-210 and
Pb-210 emissions is the electric furnace. The Po-210 and Pb-210 that
enter the furnace with the nodules are partitioned among four discharge
streams--slag, ferrophosphorus, primary phosphorus/CO gas stream, and
fugitive emissions from furnace tapholes. The data presented in
Section 2.2.2 indicate that of the total Po-210 that enters the plant with
the ore, 5 to 60 percent is contained in the slag and less than
0.1 percent is contained in the ferrophosphorus. For Pb-210, the
percentages range from 20 to 60 percent and less than 0.1 percent for slag
and ferrophosphorus, respectively. Plant personnel contacted during site
visits indicated that these estimated Po-210 concentrations are higher
than the concentrations that they would expect to remain in the slag given
the high temperatures reached in the furnace. Also, as described in
Section 2, radionuclides in the slag are difficult to sample and analyze,
and the concentrations that were reported have large uncertainties.
Consequently, the information on distribution of Po-210 and Pb-210 is not
considered to be reliable.

The Po-210 and Pb-210 that are emitted from the tapholes may be
captured by localized hoods and collected by the emission contro? system,
or they may be emitted to the atmosphere through furnace shop windows,
doors, and roof monitors. No data are available on the quantities that
are collected by the emission control system. However, the data in
Table 3-1 indicate that as much as 0.31 Ci/yr of Po-210 and 0.005 Ci/yr of
Pb-210 are emitted from the furnaces. Note that these levels are quite
small in comparison to kiln emissions. The Po-210 and Pb-210 that are
entrained in the phosphorus/CO stream can be collected in the ESP (if one
is used), condensed with the phosphorus, or returned to the kiln with the
CO. Plant personnel had no data on the radionuclide content of the ESP
dust but did indicate that virtually no radionuclides were collected with
the phosphorus. The kiln emission rates account for any Po-210 or Pb-210
that returns to the kiln with the CO.

Fugitive PM emissions from transfer and storage of ore, nodules, and
waste streams also can be a source of Po-210 and Pb-210. The only storage
and transfer operations for which emission data are available are those
related to nodule handling. Generally, these operations are enclosed, and

3-7


identified, and an emission test program that addressed those gaps was
conducted concurrently with this study. The results of that test program
are included in this report. Second, plant visits were conducted at each
of the five operating facilities to collect data on process and control
system operations, process residuals and emissions, and control system
performance and cost. Finally, additional information on control system
performance and costs was obtained through a literature review, contact
with knowledgeable EPA personnel, and telephone contacts with control
equipment vendors.

The results of this study are presented in the four sections which
follow. Section 2 contains a description of the elemental phosphorus
industry. It describes the elemental phosphorus production process and
presents data on the distribution of radionuclides in process streams and
residues. Section 3 discusses emissions from the elemental phosphorus
production process. Sources of radionuclide emissions are identified, and
estimates of Po-210 and Pb-210 emissions from the different sources are
presented. Detailed information on Po-210, Pb-210, particulate matter
(PM), and acid gas emissions from the calcining/nodulizing operation is
presented, and baseline estimates of PM and radionuclide emissions from
those operations are developed for each operating facility. Section 4
addresses control of calciner/nodulizing kiln radionuclide emissions.
Potential control techniques are described, and procedures for estimating
the performance and cost of these techniques are presented. Specific
control alternatives for calciner operations are defined in Section 5, and
estimates of the performance and costs of these alternatives are
developed.

1-2

«


TABLE 3-9. BASELINE Po-210 AND Pb-210 EMISSIONS

—— SS

Actual PM Regulatory

emissions, Ci/yr emission , baseline, Ci/yr
Facility Sg oto limit, Ib/h’  Po-2 Pb-210
FMC-Idaho* 10.0? 0.14¢ 304 57 0.29
Monsanto-Idaho® 1.44 0.344 33 4.9 1.3
Stauffer-Mont® o.7af gf 589 6.0 0.89
Stauffer-Tenn." | 0.281 0.058! 78.4 0.26 0.0056
Occidental-Tenn. 0.315 9. 064d 437 1.5 0.31

ae

pBased on facility production data.

Based on EPA tests of 1983 and 1988.

qAssumes 90 percent operation.

Based on EPA 1988 tests. :

€assumes kiln operates 85 percent of time.

Based on EPA 1983 tests.

fBased on twice Montana limit for No. 2 kiln.

Estimated based on data supplied by facilities. Operating rate estimated
;to be in the range of 85 to 100 percent of capacity.

estimated based on Occidental emissions and relative plant capacities.
Based on plant tests conducted in 1985.

3-22


ame

1.0 INTRODUCTION

The U. S. Environmental Protection Agency's (EPA's) Office of
Radiation Programs (ORP) is developing a National Emission Standard for
Hazardous Air Pollutants (NESHAP) under the authority of Section 112 of
the Clean Air Act for radionuclide emissions from elemental phosphorus
production facilities. Background information on the elemental phosphorus
production processes, radionuclide emissions from these processes,
availability of control techniques that could reduce these emissions, and
the performance and costs of alternative control techniques is needed to
support that regulatory development effort. The ORP will use that
background information to define regulatory alternatives and to evaluate
the emission reductions, risk levels, and costs associated with each of
the regulatory alternatives.

This report presents the results of a study conducted by the
Industrial Studies Branch (ISB) in EPA's Office of Air Quality Planning
and Standards (OAQPS) that was designed to collect the background
information. The specific objectives of the study were to identify the
sources of radionuclide emissions, particularly polonium-210 (Po-210) and
lead-210 (Pb-210), from elemental phosphorus production; to determine :
baseline emissions levels of Po-210 and Pb-210 for the key emission
sources at each operating elemental phosphorus plant; to identify feasible
control alternatives; and to estimate the performance and cost of those
control alternatives. Although all potential sources of Po-210 and Pb-210
from elemental phosphorus production were considered, this study focused
on Po-210 and Pb-210 emissions from the calcining (or nodulizing
operations) because previous studies indicated that those operations are
the primary sources of radionuclide emissions from the process.
Consequently, this report deals primarily with the characterization and
control of Po-210 and Pb-210 emissions from nodulizing calciners or kilns,
but other sources of emissions are addressed briefly.

The objectives identified above were addressed through three primary
data gathering and analysis tasks. First, al] emission data generated by
EPA and elemental phosphorus facilities over the past 10 years were
compiled and analyzed. As a consequence of these analyses, data gaps were

1-1


2. The test-to-test variability at the same plants at different
times generally is greater than the within test run-to-run variability at
those same facilities. Four sets of Po-210 test data illustrate this
observation. Tests L and V were conducted at the outlet of the Monsanto
spray tower in 1983 and 1988, respectively. The within test range was
spanned by a factor of less than 1.5 for both tests while average
emissions for the two tests were 12.5 nCi/dscm and 23 nCi/dscm, a factor
of about 2. Tests at the outlet of the low-energy venturi scrubber at FMC
were conducted in 1987 (Tests J and K) and 1988 (Test T). The within test
run-to-run range spanned a factor of 2 or less for all three tests.
However, average the emission concentration in 1987 was about 1.6 nCi/dscm
and the average in 1988 was about 4.5 nCi/dscm, a factor of about 3.

Tests were conducted at the outlet of the high energy venturi scrubber in
1987 (Test M) and 1988 (Test W). The 12 measurements in 1987 ranged over
a factor of about 4 while the 3 measurements in 1988 ranged over a factor
of about 1.5. In contrast, the average emissions in 1987 were

0.23 nCi/dscm while those in 1985 were 0.95 nCi/dscm, a factor of over

4. Because the individual test runs in 1985 represent different
scrubbers, the range is larger than would be found for test runs on a
single scrubber. Hence, the between test range is slightly larger than
the within test range. Finally, tests were conducted at the outlet of the
ESP at Stauffer in 1979 (Test N) and 1983 (Test Q). Within test run-to-
run variability range over a factor of less than 2 for each test while
average concentrations for the two tests were 0.23 nCi/dscm (1979) and
1.61 nCi/dsem (1983), a factor of between 7 and 8. These data, in
combination with those presented in (1) above, suggest that the
contribution of operating variability to overall variability in emission
measurements is somewhat greater than the contribution of sampling and
analysis imprecision. ,

3. Control systems comprising a spray tower and high energy venturi
or a spray tower and wet ESP can achieve significant reductions (greater
than 90 percent) in Po-210 and Pb-210 emissions. This observation is
based on comparison of the tests at the outlet to the Monsanto spray tower
(Tests L and V) to the emissions at the venturi outlet (Tests M and W) and
the tests at the spray tower inlet (Test 0), spray tower outlet (Test P)


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5-23


Both Po-210 and Pb-210 are volatile metals. As such, it is quite
likely that they will be volatilized in the calciner and leave the
calciner with the combustion gas stream. However, data from the five
operating facilities indicate that at least some of the Po-210 and Pb-210
remains in the nodules that are fed to the electric furnace. Plant
environmental personnel and industry research personnel] contacted during
this study all agreed that any Po-210 and Pb-210 that does reach the
electric furnace would be volatilized and returned to the kiln with the
CO. Available data generally support this conclusion, but limited data
from the EPA facility studies indicate that some Po-210 and Pb-210 is
deposited in the slag.” However, these data should be viewed with caution

“ because slag streams are difficult to sample and analyze and because
Po-210 and Pb-210 concentrations in the slag depend on the age of the
slag. This age dependence results from decay of other radiouclides that
are known to be present in the slag.

Tables 2-4 and 2-5 summarize available data on Po-210 and Pb~210 in
elemental phosphorus streams. These data generally suggest that most
Po-210 and Pb-210 concentrates in the kiln exhaust stream, but they do not
demonstrate conclusively that this stream is the only pathway for these
constituents. In particular, they indicate that significant quantities of
Po-210 and Pb-210 remain in the slag in some cases. During plant visits,
plant personnel indicated that these levels appear to overestimate the
quantities of radionuclides in the slag. Monsanto research personnel
indicated that slag sampling was difficult, and accurate values could not
be obtained.'® However, they estimate that Po-210 concentrations in the
slag are about 5 to 10 pCi/g.

2-11


OF 9 GED GD ons
Edit; [Ediing Bibliographic Record =] Action: Action: =] View: [MARC Templat
Holdings updated

WorldCat. Characterization and control of radionuclide emissions from elemental phosphorus prod ...
OCLC 19933509 Held by EMA - 7 other holdings _
Books =| Rec Stat c Entered 19890627 Replaced 19950518

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Bui fe = Form[—s Conf [0 = Bing [= Rec [Cry rc
cont [~ — Gpub [Fite [0 = nx (0
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245 JO]? [Characterization and control of radionuclide emissions =] [Functions ea

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LIST OF FIGURES

Page

Figure 2-1. General elemental phosphorous plant process flow...... 2-7
Figure 3-1. Vapor pressure curves for Po and Pbh......cceeeeeeeceee 3-4

Figure 3-2. Summary of Po-210 emission data......... eeasces sesceee 3-13
Figure 3-3. Summary of Pb-210 emission data......... seececccecccee 3-14
Figure 4-1. Countercurrent flow spray tower......... eeeccece seeeee 4-3
Figure 4-2. Venturi sScrubber.........ccccceccccccccccseccccccecss 4H7
Figure 4-3. Wetted-throat venturi scrubber.........ecseccecsecee as 4-8
Figure 4-4. Adjustable-throat venturi scrubber.........-..eee- weee 4-9
Figure 4-5. Illustration of ESP operating principles............. « 4-12
Figure 4-6. Circular-plate type wet ESP............. ee ccccees sooee 4-14
Figure 4-7.  Flat-plate type wet ESP.........ceceeeee ste eeeeee weeee 4-15
Figure 4-8. Spray dryer/fabric filter system.......c.cceeececeeee ~ 4-18
Figure 4-9. Pulse-jet fabric filter....... a cece cece cece cececseees 4621
Figure 4-10. The HEPA filter performance CUrVe.....cccesecececees ae 4-25

Figure 4-11. Examples of HEPA filter systems.........cccccecceccees 4-27
Figure 5-1. Capital costs of control alternatives.. 5-17
Figure 5-2. Annualized costs of control alternatives.............. 5-18

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5-13


1, LIME FEEDER

2 LIME SLAKER

2. FEED TANK

4. HEAD TANK

5. SPRAY ABSORBER
6. DUST COLLECTOR
7. STACK

y
DRY WASTE

2 PARTICLE RECYCLE

Figure 4-8. Spray dryer/fabric filter system. ‘°

4-19




TABLE 2-1.

PRODUCTION OF ELEMENTAL PHOSPHORUS 1967-1987°

—

Year

Production,

Mg (tons)

Year

Production,
Mg (tons)

1987
1986
1985
1984
1983
1982
1981
1980
1979
1978
1977
1976

312,117 (343,329)
330,652 (363,717)
326,582 (359,196)
350,966 (386,063)
332,772 (366,050)
328,354 (361,189)
387,334 (426,067)
392,482 (431,730)
417,765 (459,541)
401,158 (441,274)
391,174 (430,291)
396,959 (436,655)

1975
1974
1973
1972
1971
1970
1969
1968
1967

408,642 (449,506)
476,523 (524,175)
477,748 (525,523)
490,990 (540,089)
495,535 (545,089)
542,323 (596,555)
566,347 (622,982)
557,585 (613,343)
533,642 (587,006)

2-3


because of the cleaning/condensation process used to remove dust and
phosphorus from this stream. Table 3-1 presents preliminary estimates of
the total quantities of Po-210 and Pb-210 that are emitted from the
nodulizing kiln or calciner.'"7*? These estimates are based on limited
test data and on control levels in place before 1983 and will be updated
in Section 3.2. However, they do serve to compare the relative magnitude
of calciner emissions to emissions from other processes.

Nodules are discharged from the calciner/kiln to the nodule cooler
where they are air cooled. The high-velocity airflow in the coolers
results in entrainment of PM, which contains Po-210 and Pb-210. However,
data generated by EPA, which are presented in Table 3-1, indicate that
with the exception of emissions generated at FMC, these emissions are
negligible in comparison to calciner emissions. These data are supported
by the emission estimates shown in Table 3-2, which are based on the PM
emission limits that States have established for nodule cooling emissions
and the concentrations of Po-210 and Pb-210 that have been measured in
nodules.°~°>'° These estimates are based on the assumption that Po-210
and Pb-210 are uniformly distributed throughout the calcined nodules.

This assumption is likely to produce conservatively high estimates because
volatilization in the calciner or kiln will deplete Po-210 and Pb-210 near
nodule surfaces. These surface materials are more likely to be eroded and
entrained during cooling. The differences at FMC may result from the high
temperature of the cooler exhaust which is estimated to be in the 200° to
300°C (400° to 600°F) range. It is possible that Po-210 could be
volatilized from the nodule bed in the cooler and that a portion of the
volatilized material could be emitted as a vapor at the exhaust gas
temperatures. .

The nodules are removed from the cooler and subjected to crushing and
screening operations to generate a feed that is sized appropriately for
the electric furnace. Again, fugitive PM emissions from these operations
can contain Po-210 and Pb-210. However, the data in Table 3-1 indicate
that emissions of Po-210 and Pb-210 from crushing and screening operations
are estimated to be less than 0.001 Ci/yr at each of the three plants
tested by EPA.

3-5


13,

14,

15.

16.

17.

18.

19,

20.

21.

Radian Corporation. Oraft Final Emission Test Report. Monsanto
Elemental Phosphorus Plant, Soda Springs, Idaho. Prepared for U. S.
Environmental Protection Agency under Contract No. 68-02-4338.
Research Triangle Park, North Carolina. October 1988.

Radian Corporation. Draft Final Emission Test Report. FMC Elemental
Phosphorus Plant, Pocatello, Idaho. Prepared for U. S. Environmental
Protection Agency under Contract No. 68-02-4338. Research Triangle
Park, North Carolina. October 1988.

Hesketh, H. Air Pollution Control. Ann Arbor, Ann Arbor Science.
1981.

Environment Canada. The National Incinerator Testing and Education
Program: Air Pollution Control Technology, Report EPS 3/UP/2.
Ottawa, Ontario. September 1986.

GARD, Inc. Capital and Operating Costs of Selected Air Pollution
Control Systems. Prepared for U. S. Environmental Protection
Agency. Research Triangle Park, N.C. Publication

No. EPA 450/5-80-002. December 1978.

U. S. Environmental Protection Agency. EAB Control Cost Manual,
Third Edition. Publication No. EPA 450/5-87-001A. Research Triangle
Park, N.C. February 1987.

Turner, J. H. et al. Sizing and Costing of Electrostatic
Precipitators. Part I. Sizing Considerations. Journal of the Air
Pollution Control Association. 38(4):458-421.

Turner, J. H. et al. Sizing and Costing of Electrostatic
Precipitators. Part II. Costing Considerations. Journal of the Air
Pollution Control Association. 38(5):715-726.

Telecon. Allen, K., Midwest Research Institute, with Clark, R.,
Environmental Product Sales, Inc., Raleigh, N.C. August 12, 1988.

4-48


Under these assumptions, the estimated PM efficiency of the fabric filter
is 99.87 percent. Although specific data are not available for metal-
lurgical furnaces, data from SD/FF systems on municipal combustors
indicate that efficiencies of about 99.9 percent can be achieved for
volatile metals such as lead, arsenic, and cadmium. **

4.2.4 HEPA Filters

No data were located on the performance of HEPA filters on combustion
systems or high-temperature furnaces. However, the fractional efficiency
curve in Figure 4-10 indicates that a minimum efficiency of greater than
99.998 percent is achieved on particles in the 0.1 to 0.2 um size range
and that efficiencies generally are greater than 99.999 percent. for this
study, the overall efficiency conservatively was assumed to be
99.998 percent.

4.3 COST OF CONTROL TECHNOLOGIES

The capital and annualized costs for each of the applicable control
devices were determined following the guidelines established in Capital
and Operating Costs of Selected Air Pollution Control Systems (GARD
Manual) and in the EAB Cost Control Manual, Third Edition. '7*'® These
manuals were prepared for the U. S. EPA to provide technical assistance to
regulatory agencies in estimating the cost of air pollution control
systems. The costs in the GARD Manual are based on December 1977 dollars
and those in the EAB Cost Control Manual generally are based on 1986
dollars. The costs were adjusted to mid-1988 dollars using indices
provided in Chemical Engineering and by the Bureau of Labor Statistics.
Since the same basic procedure was used to cost each of the contro]
techniques, a cost program was developed for use on a microcomputer. The
paragraphs below describe the general cost methodology and key assumptions
that were used to cost control options. Detailed assumptions for each
operating facility are presented in Appendices A through E.

The costs were calculated assuming that each of the fine PM control
measures, with the exception of the SD/FF, were added to control the
exhaust from an existing spray tower. The existing system removes most of
the large particles, quenches and cools the exhaust gas stream (thus,
reducing gas volume and ensuring condensation of gaseous radionuclide

4-41


TABLE ‘2-2. USES OF ELEMENTAL PHOSPHORUS BY-PRODUCT SLAG”

— —— _ — ——

Neutralizer for acidic soils

Road ballast

Manufacture of Portland cement

Manufacture of slag concrete blocks

Slag wool as thermal insulation ;
Ceramic bodies and glazes .
Railroad ballast and roadbeds

Fill for septic tank drainage fields

Roadway, substation, and soil stabilization at commercial
facilities and utility installations

Municipal sewage plant filter beds
Aggregate for parking lot and driveway paving
Built-up roofing aggregate

— —

2-4


4.4
1.

2.

3.

8.

10.

ll.

12.

REFERENCES FOR SECTION 4

Joseph, G., and D. Beachler, APTI Course $1:412C Wet Scrubber Plan
Review. U. S. Environmental Protection Agency. Research Triangle
Park, N.C. Publication No. EPA 450/2~82-020. March 1984.

Memo and attachments from Wallace, D. and K. Leeds, Midwest Research
Institute, to Beck, L., EPA/ISB. August 9, 1988. Site Visit--
Monsanto Elemental Phosphorus Plant, Soda Springs, Idaho.

Memo and attachments from Wallace, D. and J. Obremski, Midwest
Research Institute, to Beck, L., EPA/ISB. August 23, 1988. Site
Visit--Stauffer Elemental Phosphorus Plant, Mount Pleasant,
Tennessee.

Schifftner, K. and H. Hesketh. Wet Scrubbers, A Practical
Handbook. Chelsea, Lewis Publishers, Inc. 1986.

U. S. Environmental Protection Agency. Control Techniques for
Particulate Emissions from Stationary Sources--Volume I. Publication
No. EPA-450/3-81-005a. Research Triangle Park, N.C. September 1982.

Reference was eliminated to prevent disclosure of CBI data.

Memo and attachments from Wallace, D. and J. Obremski, Midwest
Research Institute, to Beck, L., EPA/ISB. August 9, 1988. Site
Visit--Stauffer Elemental Phosphorus Plant, Silver Bow, Montana.

U. S. Environmental Protection Agency. Operation and Maintenance
Manual for Electrostatic Precipitators. Publication
No. EPA/625-1-85/017. Research Triangle Park, N.C. September 1985.

Beachler, D., APTI Course SI:412B, Electrostatic Precipitator Plan
Review. Prepared for U. S. Environmental Protection Agency.
Research Triangle Park, N.C.» Publication No. EPA 450/2-82-019.
duly 1983.

Sedman, C. and T. Brna. Municipal Waste Combustion Study: Flue Gas
Cleaning Technology. Prepared for U. S. Environmental Protection
Agency. Research Triangle Park, N.C. Publication

No. EPA 530-SW-87-021d. June 1987.

Beachler, 0., APTI Course SI:412A, Baghouse Plan Review. Prepared
for U. S. Environmental Protection Agency. Research Triangle Park,
N.C. Publication No. EPA 450/2-82-005. April 1982.

Burchsted, C. A., Fuller, A. B., and Kahn, J. &. Nuclear Air

Cleaning Handbook. Oak Ridge National Laboratory, Oak Ridge,
Tennessee. ERDA Publication No. 76-21. 1976.

4-47


scrubber/ESP inlet, based on the assumptions that a spray tower is located
upstream from primary control device are:

Emissions, Ci/yr
Facility 0-2 Pb-210

FMC 10 0.14
Monsanto 30 9.5
Stauffer, Montana 2.4 0.32
Stauffer, Tennessee 0.28 0.058
Occidental 0.31 0.064

The estimates for FMC, Monsanto, and Stauffer, Montana, are based on tests
conducted by EPA in 1983 and 1988 that measured emissions at the outlet of
low-energy scrubbers at those faci lities.'~? Because the control systems
at the two Tennessee plants consist of spray tower scrubbers, the emission
estimates for those two facilities are based on the baseline emissions
from those facilities that were presented in Table 3-9. Estimates of the
particle size distribution for these emissions are presented in Table 5-1.
Separate estimates were developed for moving grate calciners (FMC) and
rotary kilns (all other facilities).

The performance models presented in Chapter 4 and available test data
were used to develop estimates of the fractional efficiencies that could
be achieved by the venturi scrubber and wet ESP control alternatives for
the six particle size fractions identified in Table 5-1. The results of
the model calculations are presented in Table 5-2 for the four venturi
scrubber alternatives and in Table 5-3 for wet ESP's. Generally, the
models indicated that all of the contro] measures are relatively effective
in removing particles greater than 1 um in diameter. However, only the
high efficiency systems (venturi scrubbers with AP's of 10 kPa or greater
and wet ESP's with an SCA of 78.8 (m/s)~*) are effective in controlling
particles less than 1 um in diameter, which is the size fraction in which
the Po-210 and Pb-210 are concentrated.

Because the model results and test results agreed well for wet ESP's,
the fractional efficiencies presented in Table 5-3, the particle size
distributions presented in Table 5-1, and the estimated annual inlet
emission rates presented above were used directly to estimate annual
Po-210 and Pb-210 emission rates.


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4-15


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4-21



below describe the major components of this process and identify points in
the process where operations differ significantly among the plants.

Phosphate ore is mined offsite and is shipped by rail or truck to
each of the five plants for processing. The three western plants receive
their ore from Idaho mines that operate about 7 months per year. These
plants stockpile large amounts of ore during the summer months to continue
process operations during the winter months. The two Tennessee plants
receive ore from Tennessee mines 12 months per year. At each of the
plants, the ore is stockpiled and then processed before it is fed to the
calciner. The specific processing steps vary depending upon the ore
characteristics and calciner operations as described below.

At FMC, the ore is screened to remove oversized material, which is
sent to an ore crusher for processing. The screened material and fines
generated by the process are formed into briquettes by briquette
presses. The briquettes are screened, and the fines are recycled to the
briquetting process. The briquettes are then used as feed to the
calciner.

At the other four plants, as-received ore is blended with recycled
fines to form the feed to the calciner. The principal difference in the
facilities is that the Tennessee plants use an ore that has been washed.
Consequently, the moisture content of the calciner feed is higher at these
plants than at the western plants.

The prepared phosphate ore blend is fed to one of two types of
"calciners"--a traveling-grate calciner (FMC only) or a rotary kiln. The
objective of the calcining process is to remove moisture from the ore,
combust any volatile constituents in the ore, and produce a feedstock for
the electric furnace that is physically stable and appropriately sized.

In the traveling-grate calciner, the preformed briquettes are placed in
pallets to a fixed depth. The pallets move through the calciner, and the
briquettes are heated to a temperature of about 1300°C (2400°F) by
overfire burners that are fueled by CO or natural gas. An induced draft
fan pulls the combustion gases downward through the bed. In the rotary
kiln, the phosphate ore blend is fed continuously to the upper end of the
kiln. As the ore moves through the kiln, moisture and volatiles are
driven off, and the remaining material is heated to a temperature of about

2-8


5.0 CONTROL ALTERNATIVE PERFORMANCE AND COST

Information on the feasibility, performance, and costs of alternative
emission control techniques for elemental phosphorus process calciners and
nodulizing kilns is needed to assess potential regulatory limits for
Po-210 and Pb-210 emissions. This section defines viable control
alternatives and presents information on the performance and capital and
annualized costs of those alternatives for each of the five operating
facilities. Nationwide reductions in Po-210 and Pb-210 emissions also are
estimated, and total nationwide capital and annualized cost estimates are
presented. The results presented in this section are based on the
emission data presented in Section 3.0 and the performance and cost
estimation procedures presented in Section 4.0 for different control
technologies.

5.1 DEFINITION OF CONTROL ALTERNATIVES

As outlined in Section 4, four fine PM control techniques were
identified as having potential for control of Po-210 and Pb-210 emissions
from calciners--venturi scrubbers, wet electrostatic precipitators
(ESP's), spray dryers with pulse jet fabric filters (SD/FF's) and high
energy particulate air (HEPA) filters. Ten different control alternatives
based on these four technologies were examined. Four of the alternatives
are based on venturi scrubbers at different pressure drops (AP's), four
are based on wet ESP's with different specific collecting areas (SCA's),
and one each is based on a SD/FF system and a HEPA filter system. The
paragraphs below describe the control] alternatives and the assumptions
that were used to assess performance and cost of these systems. .

Four of the control alternatives comprise venturi scrubbers operated
downstream from a spray tower. Four different pressure drops were
examined--2.5 kPa (10 in. w.c.), 6.2 kPa (25 in. w.c.), 10 kPa (40 in.
w.c.), and 20 kPa (80 in. w.c.). The values from 2.5 kPa to 10 kPa
represent the range of aP's for venturi scrubbers at recently installed
control systems on elemental phosphorus plant calcining operations. The
20 kPa level was selected as a control alternative that is more stringent
than the controls typically used in the industry, but that has been
applied to other metallurgical processing facilities. Two other

5-1


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2-13




stoichiometric ratio of lime to HF and SO, combined. The gas temperature
at the FF iniet was assumed to be 150°C (300°F). An air-~to-cloth ratio of
121.2 m?/m?/min (4:1 ft?/ft*/min) and a system pressure drop of 3.1 kPa
(12.5 in. w.c.) were used.

Total direct costs for the SD/FF unit were estimated on the basis of
the cost equation:

0,817

C= 7.115 Q

where:
C = total direct cost, $x10° in December 1987

Q = volumetric flow, acfm

This cost equation is based on comprehensive information collected by EPA
as a part of the municipal waste combustion study. Vendors contacted
during this study indicated that these costs would provide reasonable
+30 percent estimates.
4.3.4 HEPA Filter Cost Assumptions

Calciner gas stream characteristics that affect HEPA filter design
and costs are moisture content, inorganic acid content, and loading in the
gas stream to be treated. A spray tower is assumed to exist upstream of
the HEPA filtration system; the high moisture content of the spray tower
exit gases requires treatment of the gases by a demister and reheater
upstream of the HEPA filter. These components were included in the cost
of the HEPA system. Because the exhaust gases are corrosive, Type 304
stainless steel housings and filter frames, acid-corrosion resistant
filter media, and vinyl-clad aluminum separators are included in the cost
of the system and replacement filters to provide the best available
corrosion resistance. Because the PM loading in the gas stream exceeds
the recommended maximum of 2.3 mg/m? (0.001 gr/acf), the cost of a
prefiltration system is included in the total system cost. Estimated
costs of the HEPA system, consisting of the prefilters, HEPA filters,
prefilter/HEPA filter bank housing, demister, reheater, and demister/
reheater housing were obtained from equipment vendors.

4-45


of time the wind exceeds 5.4 m/s 100 percent, and the percentage of days
with precipitation 0 percent. Under these worst-case scenarios, all
plants are estimated to have Po-210 and Pb-210 emissions of less than
0.003 Ci/yr for materials handling and less than 0.0003 Ci/acre/yr for
wind erosion.
3.2 KILN EMISSION CHARACTERIZATION

As indicated by the information presented in Section 3.1, the
nadulizing kiln (or calciner) is by far the greatest source of Po-210 and
Pb-210 emissions from elemental phosphorus production. Consequently,
control technology analyses presented in Section 4.0 focus on this
emission source. This section provides a comprehensive review of
available calciner emission data. It is divided into three subsections.
The first presents information on Po-210, Pb-210, and PM emission rates.
The second discusses acid gas emissions from the calcining operation, and
the third presents data on Po-210 and Pb-210 particle size distributions.
3.2.1 Mass Emission Rates of Po-210, Pb-210 and PM

The emissions of PM and radionuclides from elemental phosphorus plant
calcining operations have been tested extensively by both EPA and the
facilities since 1977. Data are available for four of the five operating
facilities. Although these tests provide a firm basis for regulating
radionuclide emissions, evaluation of the data to identify general emis-
sion trends is complicated by the plant-to-plant variations in processes
and air pollution control systems and by the inherent uncertainties that
result from complex sampling situations (high moisture, high temperature,
and cyclonic flows) and radionuclide analytical techniques. The available
test data are summarized in Tables 3-3 through 3-5. Table 3-3 identifies
test locations and presents information on stack gas conditions.
Table 3-4 presents PM emission rates and concentrations, and Table 3-5
presents Po-210 and Pb-210 emission concentrations and annual emission

rates.

Figures 3-2 and 3-3 present a more detailed summary of the emission
concentration data for Po-210 and Pb-210, respectively. In each figure,
run-specific emission concentrations are presented for the test series
that are summarized in Table 3-5. The data are grouped into one of four
levels of control--no control, low-energy scrubber, venturi scrubber, and

3-9


1300°C (2400°F) by combustion gases that flow through the kiln counter-
current to the ore. At those temperatures, the ore is heated to its
incipient melting point, and the tumbling action of the kiln agglomerates
the material into larger nodules. Typically, the kilns have a solids
residence time of about 4h. The kilns are fueled by a combination of CO,
coal, and natural gas.

Both types of calciners generate large quantities of high-temperature
combustion gases. Volumetric flows for the calciners currently operating
range from about 3,700 to 11,000 m/min (130,000 to 400,000 acfm) at
temperatures in the range of 320° to 430°C (600° to 800°F). Two of the
five plants use a waste heat boiler for energy recovery. The gases from
the kiln or boiler are treated in an air pollution control system before
they are discharged to the atmosphere. The air pollution control systems
for the five plants are described in Section 4. Details on the combustion
gas characteristics and kiln operating rates are presented in Appendices A
through E.

The nodules or briquettes that leave the calciner are air cooled and
subjected to crushing and sizing operations. Materials that are
approximately 1.5 to 2.5 cm (0.6 to 1.0 in.) in diameter are sent to the
feed proportioning area for the electric furnace. Undersized material is
recycled to the ore blending area and subsequently through the calciner.

The nodulized or briquetted phosphate feed material is sent to a
proportioning area where it is mixed with sized coke and silica to obtain
the required weight proportion of furnace feed (burden). A proper ratio
of Si0, to CaO is required to form slag with the necessary flow properties
to facilitate removal from the furnace. Coke is added as a carbon source
to reduce the intermediate reaction product P,0, to elemental
phosphorus. This proportioned furnace feed burden is conveyed to the
furnace burden bins.

The electric furnace is a large chamber lined with carbon blocks in
the lower section. Three consumable carbon electrodes extend through the
roof to conduct the electric current. An electric arc is formed between
the electrodes and the furnace lining. The burden material is gravity fed
continuously to the top of the furnace from where it progresses downward
until it is heated and eventually melts in the intense heat of the

2-9


characteristics. Particle collection is accomplished by exposing the gas
stream to a high-energy electrical field which charges particles and moves
them to an oppositely charged surface (the collection electrode) where
they are collected. The primary characteristic that distinguishes wet
ESP's from dry ESP's is the use of liquid flow rather than rapping to
remove the collected PM from the collection electrode. The discussion
below addresses only wet ESP's.

The basic principles of the electrostatic precipitation process are
(1) development of a high-voltage direct current that is used to charge .
particles in the gas stream, (2) development of an electric field in the
space between the discharge electrode and the positively charged collec-
tion electrode that propels the negatively charged ions and particulate
matter toward the collection electrode, and (3) removal of the collected
particulate by use of water flushing. These basic principles of the
electrostatic precipitation process are illustrated in Figure 4-5.

The electrostatic precipitation process occurs within an enclosed
chamber; a high-voltage transformer (to step up the line voltage) and a
rectifier (to convert AC voltage to OC) provide the power input. The
precipitation chamber has a shel! made of metal, tile, or fiberglass-
reinforced plastic (FRP). Suspended within this shell? are the grounded
collecting electrodes (usually plates), which are connected to the
grounded steel? framework of the supporting structure and to an earth-
driven ground. Suspended between the collection plates are the discharge
electrodes, also known as corona electrodes, which are insulated from the
ground and negatively charged with voltages ranging from 20 kV to
100 kV. The large difference in voltage between the negatively charged
discharge electrode and positively charged collection electrode creates
the electric field that drives the negatively charged ions and particles
toward the collection electrode.

The last segment of the process covers the removal of the dust from
the collection electrodes. In wet ESP's, the collected particulate matter
is removed by an intermittent or continuous stream of water that flows
down aver the collection electrodes and into a receiving sump. The liquid
from the sump is circulated through a treatment system to remove suspended
particles and adjust pH.

4-11


Control Alternative
Capital Costs

Control

VS/10

VS/25

vs/40

VS/80
WESP/200
WESP/400 | Wh:
WESP/600 a
WESP/800

SD/FF

HEPA

io) 10 20 30 40 50 60 70
Cost-$ Millions

Ml FMc Monsanto [__] Occidental
Stauf, MT Stauf, TN

Figure 5-1, Capital costs of control alternatives.

5-17


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TABLE
TABLE
TABLE
TABLE

TABLE

TABLE

TABLE
TABLE
TABLE
TABLE
TABLE
TABLE
TABLE

TABLE
TABLE
TABLE
TABLE
TABLE

TABLE
TABLE

2-1,
2-2.
2-3.
2-4,

2-5.

3-1.

3-2.
3-3.
3-4,
3-5.
3-6.
3-7.
3-8

3-9,
4-1.
4-2.
4-3.
4-4,

§-1.
5-2.

LIST OF TABLES

PRODUCTION OF ELEMENTAL PHOSHPORUS 1967-1987..........--
USERS OF ELEMENTAL PHOSPHORUS BY-PRODUCT SLAG...........

OPERATING ELEMENTAL PHOSPHORUS PLANTS, 1988..

Po-210 CONCENTRATIONS IN ELEMENTAL PHOSPHORUS PROCESS

STREAMS. ...0cescecescsccscnccccssccscs

Pb-210 CONCENTRATIONS IN ELEMENTAL PHOSPHORUS PROCESS

STREAMS......ceeeees

RADIONUCLIDE EMISSIONS FROM ELEMENTAL PHOSPHORUS

OPERATIONS... ...scccecceseccceceseccscece

NODULE COOLER EMISSION ESTIMATES......scesecececseecseee

SUMMARY OF TEST CONDITIONS.......esecceccceccccccescsces

CALCINER PM EMISSION DATA...... rere
CALCINER RADIONUCLIDE EMISSION DATA......secececececeee
ACID GAS EMISSION LEVELS. .ceeeeessscceeeesssssseeeeeeeee
PARTICLE SIZE DISTRIBUTION BASED ON IMPACTOR SAMPLES....
PARTICLE SIZE DISTRIBUTION BASED ON SASS CYCLONE

SAMPLES. .....-eeee0e

ESTIMATES OF VENTURI SCRUBBER PERFORMANCE......

SUMMARY OF ESP EFFICIENCY CALCULATIONS.......
ASSUMPTIONS USED IN ESTIMATING DIRECT AND INDIRECT

COSTS.......2-0eee ..

PARTICLE SIZE DISTRIBUTIONS FOR Po-210 and Pb-210.......

ESTIMATED FRACTIONAL EFFICIENCIES FOR VENTURI SCRUBBER

CONTROL ALTERNATIVES

Page
2-3
2-4
2-6

2-12

2-13

3-2

3-6

3-10
3-11
3-12
3-18
3-19

3-20
3-22
4-34
4-36
4-39

4-43
5-5


4-4, ASSUMPTIONS USED IN ESTIMATING DIRECT AND INDIRECT COSTS@

TABLE
esp VS FF
Direct costs
Purchased equipment costs b
« Control device AR AR AR
2. Auxiliary equipment AR AR AR
3. Instruments and controls 0.10 0.10 0.10
4. Taxes 0.03 0.03 0.03
5. Freight 0.05 0.05 0.05
Total 1.00 1.00 1.00
Installation direct costs
+ Foundations and supports 0.04 0.06 0.04
2. Erection and handling 0.50 0.40 0.50
3. Electrical 0.08 0.01 0.08
4. Piping 0.01 0.05 0.01
5. Insulation 0.02 0.03 0.07
6. Painting 0.02 0.01 0.02
7. Site preparation AR AR AR
8. Facilities and buildings AR AR AR
Total 1.67 1.56 1.72
Indirect costs
Installation indirect costs
T. Engineering and supervision 0.20 0.10 0.10
2. Construction and field expenses 0.20 0.10 0.20
3. Construction fee 0.10 0.10 0.10
4. Startup 0.01 0.01 0.01
5. Performance test 0.01 0.01 0.01
6. Model study 0.02 0.02 0.02
7. Contingencies 0.03 0.03 0.03
Total 2.24 1.91 2.17

@the numerical factors are multiplied by the purchased equipment costs to
podtain total costs.
‘AR = as required.

4-43


Pb-210 Concentration (nCi/dscm)

10

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0.1

0,01

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Figure 3-3. Summary of Pb-210 emission data.

3-14



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5-28


assumptions were made in evaluating the performance and costs of the
venturi scrubber control alternatives. First, a spray tower was assumed
to be used upstream from the venturi to control acid gases and condition
the gas stream for the venturi. All of the operating facilities except
FMC currently have a spray tower as a part of their control system that is
assumed to be useable as the conditioning system for the venturi. Second,
for all the venturi scrubber control alternatives, the L/G ratio was
assumed to be 1.3 2/m> (10 gai/1,000 ft’). This value was selected
because it represents the upper end of the range typically found in
venturi scrubber applications. A cyclonic mist eliminator also was
assumed for all venturi scrubber alternatives. Note that although FMC
does not have a spray tower in their systems, no tower was costed for this
study. The low energy scrubber that FMC has in place as assumed to
provide coarse PM control and gas conditioning.

The four ESP control alternatives that were considered comprised
spray towers for acid gas control and gas stream conditioning followed by
flat-plate wet ESP's. The four SCA levels that were considered were-

39.4 (m/s)~* (200 ft?/kacfm), 78.8 (m/s)~* (400 ft?/kacfm), 118 (m/s)7*
(600 ft?/kacfm), and 158 (m/s)~' (800 ft?/kacfm). These four SCA levels
are higher than the SCA at the one wet ESP that is applied to a nodulizing
kiln. However, that unit is an older unit with relatively low PM removal
efficiency. The range of 39.4 to 158 (m/s)7* (220 to 800 ft? /kacfm) is
representative of the SCA levels typically found on metallurgical and
mineral processing facilities. The spray tower upstream from the ESP will
remove acid gases from the gas stream and reduce the temperature to 65° to
70°C (150° to 160°F) to assure that the Po-210 and Pb-210 are condensed
before they enter the ESP. :

The ninth control alternative is the SD/FF control system described
in Section 4.1.4. For this alternative, the exhaust stream is vented
directly to the spray dryer without pretreatment. No SD/FF systems have
been applied to elemental phosphorus facilities. However, they were
selected as a stringent control technique because they have been
demonstrated to control acid gases and condensation PM in other
metallurgical and mineral processing operations such as aluminum reduction
and glass manufacturing. Key assumptions that were made to estimate

5-2


and ESP outlet (Tests Q and N) at Stauffer. The performance of these
control systems is analyzed in more detail in Section 4.
3.2.2 Acid Gas Emissions

Elemental phosphorus calcining operations are sources of acid gas
emissions that can include SO,, HF, HCl, and P,0,. However, the primary
constituents are SO, and HF. These acids are generated by fluorides and
sulfides that are contained in the phosphate ores and in coal that is used
to supplement the CO as fuel in the calciner. This study is not concerned
directly with acid gas emissions, but they do play an important role in
evaluating emission control alternatives. Consequently, available data
were collected from emission test reports, and information on acid gas
levels was requested from plant personnel during plant visits. The
limited data that were obtained are presented in Table 3-6.

3.2.3 Po-210 and Pb-210 Particle Size Distributions

The control technology assessments in Chapter 4 require an estimate
of the particle size distributions of Po-210 and Pb-210 emissions. The
only radionuclide-specific particle size data that were identified during
this study were those generated by EPA in support of NESHAP development.
Ouring that comprehensive test program, particle size data were collected
at the inlets and outlets of control systems at the three Western plants
using one of two methods--a cascade impactor or the SASS cyclones. The
data generated from that program are tabulated in Tables 3-7 and 3-8 for
the impactor samples and SASS samples, respectively.

The data in Table 3-7 indicate the distributions at the scrubber
inlet are distinctly different from those at the outlet at FMC. In
general, the inlet data are bimodal with significant fractions of the
emissions less than 1.0 ym and greater than 10 um in diameter. At the
outlet, over 70 percent of the Po-210 and Pb-210 were in the two fractions
that were less than 0.9 um in diameter except for the Pb-210 on Calciner
No. 1 at FMC. Consequently, additional controls must focus on submicron
PM.

The data in Table 3-7 also indicate that the distributions of both
Po-210 and Pb-210 at Stauffer and Monsanto are different from those at
FMC. However, the SASS results in Table 3-8 and the cascade impactor
tests in Table 3-7 indicate that the distributions at Monsanto are