EPA-450/3-78-109
Screening Study on Feasibility
of Standards of Performance
for Hydrofluoric Acid Manufacture
by
Vladimir Boscak
The Research Corporation of New England
125 Silas Deane Highway
Weathersford. Connecticut 06109
Contract No. 68-02-2615
Task No. 6
EPA Task Manager: Kenneth R. Woodard
Emission Standards and Engineering Division
Prepared for
U S. ENVIRONMENTAL PROTECTION AGENCY
Office cf Air, Noise, and .Radiation
Office of Air Quality Planning and Standards
Research Triangle Park. North Carolina 27711
October 1373
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This raport has been reviewed by the Emission Standards and Engineering Division of the Office of Air
Quality Planning and Standards, EPA, and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Environmental Protection Agency, nor does
mention of trade names or commercial products 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, N.C. 27711; or, for a fee, from the National Technical
Information Services, 5285 Port Royal Road. Springfield, Va. 22161.
Publication No. EPA-450/3-78-109
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TABLE OF CONTENTS
SECTION PAGE
1.0 ABSTRACT 1
2.0 EXECUTIVE SIE1MARY 2
3.0 CONCLUSIONS AND RECOMMENDATIONS 6
3.1 Conclusions , 6
3.2 Recommendations 6
4.0 HYDROFLUORIC ACID MANUFACTURING INDUSTRY - ECONOMIC
PROFILE AND STATISTICS „ 7
4.1 Industry Size and Geographic Location 7
4.2 Capacity Utilization and Consumption 10
4.3 Industry Growth Trends ., 13
4.4 References 16
5.0 HYDROFLUORIC ACID MANUFACTURING PROCESS 17
5.1 Hydrofluoric Acid Manufacturing Chemistry 17
5.2 Typical Hydrofluoric Acid Manufacturing Process 19
5.3 Major Variations of Hydrofluoric Acid Manufacturing
Processes 25
5.4 Recovery of Fluoride Value From Phosphate Rock 33
5.5 References 37
6.0 EMISSION SOURCES AND RATES IN HF PRODUCTION AND
MANUFACTURING 38
6.1 Sources and Nature of Point Source and Fugitive
Emissions 38
6.2 Controlled and Uncontrolled Emission Rates 40
6.3 Annual Emission Rates arid Plant Inventories 44
6.4 Gypsum Pond Emissions 48
6.5 References 51
7.0 CONTROL OF EMISSIONS FROM HF MANUFACTURE 52
7.1 Particulate Emission Control 52
7.2 Gaseous Emission Control 57
7.3 Fugitive Emission Control 68
7.4 Summary of Best Control Technology 69
7.5 References 72
8.0 STATE AND LOCAL EMISSION REGULSTIONS 73
8.1 Summary of Applicable Emission Regulations 73
3.2 List of Regulations Applicable to the Hydrofluoric
Acid Manufacturing Industry 74
8.3 Definition of Plant Modification 94
8.4 References 96
iii
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TABLE OF CONTENTS (Continued)
SECTION PAGE
9.0 HP MANUFACTURE EMISSION SOURCE SAMPLING AND ANALYSIS .... 97
9.1 Particulates 99
9.2 Total Fluorides . 99
9.2.1 TRC's Experience With Fluoride Sampling and Analysis . .103
9.2.2 Remote Sensing of Fluoride Emissions 108
10.0 ENVIRONMENTAL EFFECTS OF FLUORIDE EMISSIONS 113
10.1 Vegetation Effects 113
10.2 Effect on Farm Animals 115
10.3 Effects in Man 117
10.4 Other Effects 118
10.5 References 118
11.0 EMISSION REDUCTION WITH NEW SOURCE PERFORMANCE STANDARDS . .119
11.1 Introduction 119
11.2 Model IV - Background Information 120
11.3 Industrial Factors 124
11.4 Emission Factors 127
11.5 Results of Model IV Calculations 128
11.6 References 129
12.0 LIST OF CONTACTS 130
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LIST OF FIGURES
FIGURE PAGE
£-1 Location and Relative Capacity of Hydrofluoric
Acid Manufacturers9 8
5-1 Schematic Flow Diagram for the Manufacture of
Hydrogen Fluoride-' 24
5-2 Process Flowsheet for the Manufacture of
Hydrofluoric Acid3 Using Buss Technology 26
5-3 Anhydrite Recovery Flowsheet3 28
5-4 EPA Exemplary Hydrofluoric Acid Process Flow Diagram . . 32
5-5 Vertical Hydrolysis System11 35
6-1 Typical Tail Gas Exhaust Stack 41
6-2 Hydrofluoric Acid Production - Uncontrolled
Process Model1 42
6-3 HF Production - Controlled Process Model1 45
6-4 Effluent Recycle System at an Exemplary Plant5 . 49
7-1 Baghouse for Control of Spar Emission 54
7-2 Typical Baghouse with Pulsed Air Cleaning1 55
7-3 Kiln Venturi Scrubber System3 56
7-4 Relationship Between Collection Efficiency and
Particle Size in Venturi Scrubbers 58
7-5 Typical Packed Tower3 . . 59
7-6 Power Consumed in HF Absorption 62
7-7 Power Consumed in SiF^. Absorption 63
7-3 Power Consumed in Absorbing S0£ 64
7-9 Typical Tank Car Unloading Connections When Using
Compressed Air for Unloading Anhydrous
Hvdroflucric Acid' 70
v
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LIST OF FIGURES (Continued)
FIGURE PAGE
3-1 Ohio Collector Efficiency Curve1* 80
8-2 Pennsylvania Allowable Emissions Curve for
Sources Not Listed in Section 123,136 83
8-3 Texas Allowable Particulate Emission Rates
for Specific Flow Rates7 86
8-4 Texas Allowable Particulate Emission Rates
for Specific Flow Rates7 87
8-5 Texas Fluoride Standards 88
Graph 1 89
Graph 2 90
9-1 Method 5 Particulate-Sainpling Train 100
9-2 Method 17 Particulate-Sampling Train, Equipped
With Iii-Stack Filter 101
9-3 Schematic of a Ground Upwind-Downwind and
Vertical Traverse Sampling Station 104
9-4 Experimental Arrangement for Evaluation of
Hydrogen Fluoride Sampling and Analysis 105
9-5 EPA ROSE Infrared Spectrometer System 109
9-6 Gypsum Pond Spectra 112
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LIST OF TABLES
TABLE PAGE
4-1 Hydrofluoric Acid Manufacturing Plants in the
United States 9
4-2 Population Statistics . 12
4-3 Hydrofluoric Acid Production 13
4-4 1976-1977 Producton of Fluorocarbons Fll and F12. . . 14
4-5 Aluminum Industry Production 1975-1982 15
5-1 The Physical Properties of Anhydrous Hydrogen Fluoride 18
5-2 The Physical Properties of Fluorspar (CaF2) 19
5-3 Reactions of Fluorides. . 22
5-2 Process Flowsheet for the Manufacture of Hydrofluoric
Acid Using Buss Technology 26
6-1 Emission Factor Ranking for Hydrofluoric Acid .... 43
6-2 Soluble Fluoride Emissions from HF Production .... 46
6-3 Emission Inventory for HF Manufacturing Plants. ... 47
6-4 Waste Products from HF Manfacturing Plants. ..... 50
7-1 Advantages Si Disadvantages of Wet & Dry Air & Gas
Cleaning Devices 53
7-2 Hydrogen Fluoride Absorption Date 61
7-3 Best Control Technology in HF Manufacture . 71
8-1 San Francisco Bay Area Regulations Applicable to
HF Manufacturing 75
8-2 Kentucky State Regulations Applicable to HF
Manufacturing 76
8-3 Louisiana State Regulations Applicable to HF
Manufacturing 77
Vll
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LIST OF TABLES (Cont)
TABLE PAGE
8-4 Ohio State Regulation Applicable to HF Manufacturing . 78
8-5 City of Cleveland Regulations Applicable to HF
Manufacturing , 81
8-6 Pennsylvania Commonwealth Regulations Applicable to
HF Manufacturing 82
8-7 Texas State Regulations Applicable to Hf Manufacturing 84
8-8 West Virginia State Regulations Applicable to HF
Manufacturing 91
S-9 New Jersey State Regulations Applicable to HF
Manufacturing , 92
8-10 Summary of State Regulations on Allowable
Emissions 93
9-1 Sampling and Analysis Techniques for the Emissions
For HF 98
10-1 Hydrogen Fluoride Concentrations and Exposures for
Sensitive and Resistant Plant Species 114
10-2 Safe Level of Fluorine in Livestock Feed 116
11-1 Model IV Input Variables . ., 122
11-2 Model IV Industrial and Emission Factors -
Hydrofluoric Acid 128
vni
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DISCLAIMER
This Final Report was submitted to the U. S. Environmental Protection Agency
by TRC - TdE RESEARCH CORPORATION of New England, Wethersfield, Connecticut in
partial fulfillment of Contract No. 68-02-2615, Task No. 6. The opinions,
findings, and conclusions expressed are those of the author and not necessarily
those of the Environmental Protection Agency or of cooperating agencies. Mention
of company or product names is not to be considered as an endorsement by the
Environmental Protection Agency.
ix
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ACKNOWLEDGEMENTS
The author would like to acknowldege helpful discussions with Messrs.
Kenneth Woodard and Kenneth Durkee, Environmental Protection Agency, Office of
Air Quality Planning and Standards, Emission Standards and Engineering Division,
Raleigh - Durham, North Carolina.
In addition, the author would like to make a collective acknowledgement to
the personnel at each hydrofluoric acid manufacturing plant without whose coopera-
tion this project could not have been completed, and state and local air pollu-
tion control agencies for furnishing information to TRC. The opportunity to
visit the Allied Chemical plants in Baton Rouge and Geismar, Louisiana, the
DuPont plant in LaPorte, Texas, and the Harshaw Chemical Company office in
Cleveland, Ohio is greatly appreciated.
The following TRC personnel in addition to the author participated in this
project:: Mr. Bradley Raffle, Ms. Pamela Katz, Ms. Patricia Tyszka, Mr. Reed Cass,
and Ms. Sandv Sholovitz.
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1.0 ABSTRACT
This report contains background information on the hydrofluoric acid manu-
facturing industry. This information was obtained in the open technical literature
and through visits to several typical plants.
The economic profile of the industry indicates there will be no growth in
the next five years.
General description of manufacturing process emission sources, rates and
controls are the main part of the report. State and local emission regulations
and emission source sampling and analysis methods are also discussed.
The background information has been used in a simple emission projection
model (Model IV) to determine the emission reductions that could be achieved by
the application of New Source Performance Standards.
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2.0 EXECUTIVE SUMMARY
Industry's Economic Profile
In the United States at the present time, there are 9 hydrofluoric acic
(HF) plants in operation. Two are located in Louisiana, 2 in Texas and 1 each
in California, Kentucky, New Jersey, Ohio, and West Virginia. According to 1977
figures, the industry produced 268,000 tons of hydrofluoric acid, while 1975
data showed the annual capacity to be 369,000 tons. In recent years almost all
HF produced is in the anhydrous form. Major HF uses are fluorocarbon production
(39%), aluminum industry production (27%), and with the remaining being used for
uranium enrichment, petroleum alkylation, stainless steel pickling and miscellaneous,
The fluorocarbon aerosol ban resulted in a 20% reduction in HF production.
The volume of HF manufacture will be the same for at least the next 5 years.
While new plants are not planned two plants are expected to be closed by mid
1979. The rest of the industry will increase the utilization of their capacity
to compensate for the difference.
HF Manufacturing Process
HF is manufactured from fluorspar and sulfuric acid in a rotary kiln according
to the endothennic reaction:
CaF2 + H2SOi+ ->• CaSOv -i- 2 HF
The product anhydrite is either slurried and transferred to a gypsum pond, or
neutralized and recovered in the solid form. HF gases are first scrubbed and
cooled, and almost all HF is recovered in a condenser. The remaining HF and
impurities are scrubbed in an acid scrubber while fluosilicic acid can be re-
covered in a water scrubber. Almost all processes used a tail gas scrubber
before venting the gas to the atmosphere. Crude HF is distilled to a high
purity for a further use.
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Four major variations of HF manufacture are:
1. Buss Process
2. Typical Process (described by EPA)
3. Aluminum Fluoride Manufacture Process
4. Patented Process
HF can be recovered from a phosphate rock using silicon tetrafluoride (a by
product), but the process is in the early stages of development.
Emission Sources and Rates
There are few sources of air emissions in a HF manufacture plant. The major
source of particulate emission is fluorspar drying and handling. The literature
suggests that the spar emission rate is about 20 Ib/ton and emission data from
typical plants indicate that this emission factor is realistic. The only point
source of gaseous emission is from the tail gas scrubber. The emissions consist
of small amounts of HF, SiF^ and S0£. The HF manufacturing process model shows
that uncontrolled soluble fluoride emission is 52 Ib F/ton of HF. Controlled
emissions using a gas scrubber with 90% efficiency amount to 4 Ib F/ton HF.
Total annual emission of soluble fluoride from HF manufacture after currently
used control is 700 tons F/year. The projection for the year 2000 shows 5300
tons ?/year based on 6% yearly growth. Since this growth is probably unrealistic,
this emission projection appears to be high.
Fugitive fluoride emissions are expected from process upsets, HF handling
and the gypsum pond (with pH of 1).
The emission inventory for HF manufacturing plants is too unreliable to
develoo actual emission factors.
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Control of Emissions
Particulate emissions for spar drying and handling are controlled with
fabric filters and wet scrubbers. The best control appears to be the use
of a fabric filter with 99% efficiency. The gaseous emissions are controlled
with wet scrubbers. The best control technique is the use of a packed
tower with about 5 transfer units using alkaline scrubbing liquid which can
achieve an efficiency of 99% for removal of HF, SiFi+ and S02. HF fugitive
emissions from a kiln under upset conditions are best controlled with a stand-by
caustic scrubber. Liming of the gypsum pond to obtain a pH of 6 would prevent
any HF or SiF^ emission.
State and Local Emission Regulations
Although hydrofluoric acid manufacturing is regulated under the permit and
particulate regulations of the states where operations exist, no state has yet
adopted regulations which specifically address HF production. Rather, states
treat HF manufacturing as a process industry for purposes of air pollution control
regulations. An analysis of state regulations indicates that process weight
and/or fluoride emissions standards apply to virtually all HF plants.
Emission Source Sampling and Analysis
Sampling and analysis methods for criteria pollutants, particulate, SC>2, No
are covered under EPA Methods 5, (17), 6 and 7. Total fluoride is covered under
EPA Method 13. TRC experience indicates that a simplified sampling train can be
used for gaseous fluoride emissions measurement. Remote Optical Sensing
of Emissions (ROSE) has been developed by EFA's Environmental Sciences Research
Laboratory/HTP. This technique is well suited for the measurement of ambient
fluoride concentrations, and it distinguishes between HF and SiFu.
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Emission Reduction With NSPS
Results of the Model IV calculation indicate that there would be no reduction
in 1987 emission if NSPS are implemented. This is due to the projected lack of
increase in production volume. Review of emissions control on an industry-wide
basis shows that most plants are using best control technology. Since some
plants have better controls in one area and some in the other NSPS would bring
the plants on an equal level. It appears that fluoride emission would be reduced
by 20-30% if best control technology was applied to all plants.
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3.0 CONCLUSIONS AND RECOMMENDATIONS
3.1 Conclusions
1. No growth is expected in the HF manufacturing industry in the next 5
years. The growth after that is unpredictable but will be probably
below 6% annually (an average for last 3 decades).
2. There are 4 variations in HF manufacture that are described in this
report.
3» HF manufacturing has 2 major sources of emission: Particulate emis-
sions from spar drying and tail gas from the HF absorption train.
4.. The best control for particulate emissions are fabric filters and wet
scrubbers for tail gas containing HF, SiF^ and S02-
5. The quantitative data on gaseous emissions containing fluorides are
virtually non-existent due to the lack of regulations.
6. It is unclear whether the fluorspar should be included in the fluoride
emissions and what is its effect: on vegetation, animals and man.
7. The major problem in HF manufacturing is corrosion which can result in
HF emissions. Good maintenance is essential for proper operation.
8.. The major benefit of NSPS for this industry would be to equalize
emissions controls throughout the industry resulting in overall 20-30%
reduction in fluoride emission in the existing plants.
3.2 Recommendations
In order to obtain a better understanding of HF manufacture environmental
problems the following are recommended:
1. Measure fluoride concentrations in tail gas from HF manufacture.
2.. Quantify fugitive emissions in HF manufacture.
3.. Determine fluorspar effects and whether they should be considered
fluorides or particulates.
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4.0 HYDROFLUORIC ACID MANUFACTURING INDUSTRY - ECONOMIC PROFILE AND STATISTICS
4.1 Industry Size and Geographic Location
Hydrofluoric acid (KF) manufacturing is a segment of the inorganic chemical
industry under the Standard Industrial Classification (SIC) 2819 - Industrial
Inorganic Chemicals.
In the United States at the present time, there are 11 hydrofluoric acid
plants in operation. Three of these are located in Louisiana, three in Texas and
one each in California, New Jersey, Ohio, West Virginia and Kentucky. Figure 4-1
illustrates the approximate locations and relative size of each plant as deter-
nined by 1975 annual capacity statistics.
The tern "HF Manufacturing Plant" needs some clarification. All HF manu-
facturing facilities are a part of large chemical plants and only 20 to 90
employees out of several hundred are involved in HF production. In several
plants HF is a link in a production chain consisting of ^SOtt - HF - fluoro-
carbons. In several plants all HF manufactured is used within the plant.
According to 1977 actual data determined from the industry 268,000 tons of
hydrofluoric acid were produced for internal use and for outside consumption.
In spite of the aerosol controversy, fluorocarbon production consumed about 39%
of the total hydrofluoric acid supply. The alum-inn^ industry accounted for
about 272%. The remainder of the hydrofluoric acid supply was utilized for
uranium enrichment (62T) , stainless steel pickling (2%), alkylation of olefins
(4%) and miscellaneous application (22%). [Table 4-1 presents the annual capa-
city for each plant.]
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O 80-100 thousand tons/year
O A5-5S thousand tons/year
• 10-20 thousand tons/year
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TABLE 4-1
HYDROFLUORIC ACID MANUFACTURING PLANTS IN THE UNITED STATES
Source: 1977 Directory of Chemical Products, U.S.A. Chemical Information
Services, Stanford Research Institute
1.
2.
3.
4.
5.
6.
7.
8.
9.
PRODUCER
Allied Chem. Corp.
Indus t. Chens. Div.
Specialty Chema. Div.
Aluminum Co. of America
Ashland Oil, Inc.
Ashland Chen. Co., dlv.
Lehlgh Valley Chetn. Co. div.
E. I. du Pont de tlemoura 4 Co., Inc.
Biochems. Dept.
Essex Chem. Corp.
Chents. Dtv.
Kaiser Aluminum & Chen. Corp.
Kaiser Cliems. Div.
k'ewanee Indust., Inc.
Harshaw Chemical Co., subs id.
Indust. Chems. Dept.
Pennwalt Corp.
Inorganic Chen. Div.
Stauffer Chem. Co.
Indus t. Chem. Dlv.
LOCATION
1. Baton Rouge La.
2. dayman t Del.
3. Geismar, La.
4. Nitro, W.Va.
5. Pittsburg, Calif.
6. Marcus Hook, Pa.
Point Comfort, Tex.
Clendon, Pa.
La Porte, Tex.
Paulsboro, M.J.
Craoercy. La.
Cleveland, Ohio
Calvert City, Ky.
Greens Bayou, Tex.
ANNUAL CAPACITY
(THOUSANDS OF TONS)
20
25
45
15
12
n.a.
55
5
100
11
50
18
25
18
IN OPERATION
SIHCE
1946
1967
1959
1952
1961
1964
1972
1949
TOTAL
399
Sources: Chemical Marketing Reporter, November 17, 1973 and communication with industry.
Comments:
1.
Contacts with the industry indicate that 3 of above plants (Allied Chemical's
Clavmont. and the Ashland' plant) no longer manufacture HF ^equei^'
total annual capacity without these plants is 369 thousand tons per year.
Actual total 1977 production (obtained under confidentiality agreement) is
268 thousand tons. The discrepancy is the result of erroneous annual
capacity listing and capacity's under utilization.
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4.2 Capacity Utilization and Consumption
The existing hydrofluoric acid plants have been underutilizing their capacity
for the past several years. In 1977 the annual capacity of the industry totaled
369,000 tons, while total production amounted to 268,000 tons, or 73% of total
capacity.
The major users of all of the marketed hydrofluoric acid are the aluminum
and fluorocarbon industries. In aluminum manufacturing, the hydrofluoric acid
is not used directly in the smelting process, but goes into producing aluminum
fluoride and synthetic cryolite from reaction with alumina and caustic soda,
respectively. These products together with bauxite are then used in the molten
bath which undergoes electrolysis to produce aluminum.2 An estimated 56 pounds
of hydrofluoric acid are required to produce 1 ton of aluminum. Table 4-5 in
Section 4.3 shows the production/consumption figures for the aluminum industry.
Fluoride production accounted for 42% of the total hydrofluoric acid supply
in 1976.2 Inorganic fluorides are manufactured for utlization as preservatives,
insecticides, catalysts, fluxes, for steel pickling and for use in fire extin-
guishers. Hydrofluoric acid is used in the manufacture of elemental fluorine
gas which in turn is used to manufacture uranium hexafluoride sulfur hexafluoride,
halogen fluorides and emulsified perfluorochemicals. The organic fluorides,
which utilize the rest of the available hydrofluoric acid, are manufactured for
production of various chlorofluorocarbons. These fluorocarbons are widely used
as refrigerants, aerosol propellants, resins, solvents and elastomers.
The geographic location of the hydrofluoric acid plants is significant in
determining the potential effects of atmospheric fluorides on plants and ani-
mals. Table 4-2 gives population statistics for 1 and 5 mile circles around
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each plant. The farm statistics give an indication of the amount of agricul-
tural activity in the vicinity of each plant which may be subject to fluoride
emissions.
Based on the number of employees involved in HF manufacture and actual
production data, one can calculate that about 1.5 employees are needed to
produce one thousand tons/year of anhydrous HF. This adds up to a total of 402
employees (nationwide) in HF manufacture.
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PLANT
TABLE 4-2
POPULATION STATISTICS
(based on TELE/SITE and contacts with the industry)
EMPLOYEES POPULATION FARM POPULATION
LOCATION IN HF MANUF. 0-1 MILES 1-5 MILES 0-1 MILES - 1-5 MILES
Alcoa
DuPont
Stauffer
Allied
Allied
Kaiser
Allied
Pennwalt
Essex
Harshaw
Allied
Texas
Point Comfort 5-1 0 8,386 0
La Porte 90 13 41,335 0
Greens Bayou n.a.* 2,454 105,894 0
Louisana
Geismar 15 0 5,312 0
Baton Rouge 30 1,375 178,292 0
Gramercy n.a. 0 11,851 0
California
Pittsburg 25 28 41,079 0
Kentuckv
Calvert City 41 0 4,145 0
New Jersey
Paulsboro n.a. 8,084 158,884 5
Ohio
Cleveland 20 16,631 479,543 17
W. Virginia
Nitro 25 1,972 39,904 1
21
4
20
64
285
87
56
32
169
216
12
*n.a. = not available.
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4.3 Industry Growth Trends
The production of industrial inorganic chemicals depends upon a wide range
of economic activities and does not rely on one specific sector of the economy.
Presently, the largest consumers of hydrofluoric acid are the fluorocarbon
and aluminum industries, accounting for 42% and 32% of the total hydrofluoric
acid usage in 1976.2 A good indicator of the hydrofluoric acid production
trend is the consumption of acid-grade fluorspar used in its manufacture.
Table 4-3 illustrates the production trend from 1972 through 1977.
TABLE 4-3
HYDROFLUORIC ACID PRODUCTION
1972 - 1977
(2,3,4,5,6,7,8)
Acid -Grade
Fluorspar Consumed
(Short Tons)
HF
Produced
(Short
Tons)
Withdrawn
From
System
Not
Withdrawn
From
System
1972
752,728
248,879
93,270
1973
803,999
269,153
96,301
1974
838,211*
281,620
99,385
1975
673,626
229,247
84,138
1976
631,300
202,644
85,518
1977
!
.
560,519
182,690
73,000
*Derived by assuming 2.2 Ib acid-grade fluorspar - 1 Ib hydrogen
fluoride
Early in 1975 a controversy arose concerning the use of fluorocarbon aero-
sols and their possible effect on the ozone layer of the stratosphere. As a
result of the controversy, fluorocarbon aerosol sales decreased as did the demand
for the hydrofluoric acid used in their manufacture. In April of 1977, the
Food Drug Administration (FDA) and Consumer Product Safety Commission (CPSC)
stated the need for warning labels to be placed on all products containing
fluorocarbon propellants. Following this action in May of 1977 the EPA along
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with the FDA and the CPSC issued a set of rules which would ban fluorocarbon
aerosol propellants for nonessential uses by December 15, 1978 and would prohit
their shipment between states by April 15, 1978. ^ This ruling has had a signifi-
cant effect on hydrofluoric acid production since 1975. This controversy has
reduced the demand for HF by approximately 20%. The statistics for production
of the controversial fluorocarbon Fll and F12 for 1976 and 1977 are shown in
Table 4-4. An illustration of the reduction in fluorocarbon production is
the fact that three plants have been closed since 1975 and production at one
has declined 50%.
TABLE 4-4
1976 - 1977 PRODUCTION OF
FLUOROCARBONS Fll and F12^j '**' 5> 6 >7>
(MILLION POUNDS)
Hydrofluoric
Acid Consumed*
Fll & F12
Produced
1976
624
218
1st Qtr.
1977
140
49
2nd Qtr.
1977
158
55
3rd Qtr.
1977
144
50
4th Qtr.
1977
104
36
Total
1977
546
191
*Derived by assuming .35 Ibs HF = 1 Ib fluorocarbon
Table 4-5 presents the production statistics for the aluminum industry from
1975 through 1977 and estimated production through 1982.
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TABLE 4-5
ALUMINUM INDUSTRY PRODUCTION
1975 - 1982 (2»3»^.StS.7)
(THOUSAND TONS)
Hydrofluoric
Acid Consumed*
Aluminum
Produced
1975
109
3,880
1976
119
4,250
1977
127
4,530
1980T
164
5,857
1982'
195
6,964
*Derived by assuming 56 Ib HF » 1 ton aluminum
(via cryolite and aluminum fluoride)
tAssuaie 97, increase each year
The economic strength in HF manufacturing is that it will be indispensable to
the aluminum industry for many decades despite the introduction of aluminum
process techniques that avoid HF.'
The major weakness is the enormous aluminum inventory surplus and the de-
pressed economy. These factors are expected to keep the aluminum supply loose
and production low for several years.
In conclusion it appears that HF manufacture will not increase for at least
5 years. Contacts with the industry revealed that 1982 production will stay
on the 1977 level with a total of 254,000 tons. Two plants are expected to be
closed by mid-1979. The rest of the industry will operate at a higher capacity
to compensate for the difference. Contacts with HF manufacturers also indicate
that no new facilities or modifications are expected in the next 5 years. The
importation of HF is likely to increase.
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4.4 References
1. Inorganic Chemicals Industry Profile (Update), Datagraphics, Inc.
Pittsburgh, PA for EPA under program #12020EJ1, July 1971.
2. Division of Nonmetallic Minerals. 1977. Fluorspar in 1976. Bureau of
Mines Minerals Industry Surveys, U.S. Department of the Interior,
11 pages.
3. Singleton, Richard H. and Shelton, John E. 1975. Fluorspar. Preprint
from the 1975 Bureau of Mines Minerals Yearbook, U.S. Department of
the Interior, 19 pages.
4. Division of Nonmetallic Minerals. 1977. Fluorspar in First Quarter
1977. Bureau of Mines Minerals Industry Surveys, U.S. Department of the
Interior, 7 pages.
5. Division of Nonmetallic Minerals. 1977. Fluorspar in Second Quarter
1977. Bureau of Mines Minerals Industry Surveys, U.S. Department of the
Interior, 8 pages.
6. Division of Nonmetallic Minerals. 1977. Fluorspar in Third Quarter
1977. Bureau of Mines Minerals Industry Surveys, U.S. Department of the
Interior, 8 pages.
7. Division of Nonmetallic Minerals. 1977. Fluorspar in Fourth Quarter
1977. Bureau of Mines Minerals Industry Surveys, U.S. Department of the
Interior, 8 pages.
8. Bureau of the Census. 1978. Inorganic Chemicals February 1978. Current
Industrial Reports, U.S. Department of Commerce, 4 pages.
9. Chemical Marketing Report, Vol. 208, No. 20, November 17, 1975.
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5.0 HYDROFLUORIC ACID MANUFACTURING PROCESS
5.1 Hydrofluoric Acid Manufacturing Chemistry
H? Properties
In volume of production, HF is the most important manufactured compound of
fluorine.1 Both the anhydrous and aqueous acids are used directly or as inter-
mediates but anhydrous acid is becoming a principal product.
Anhydrous HF is a colorless liquid or gas (bp 19.5°C) , highly water soluble
and fuming strongly in contact with the atmosphere. The formula weight is 20.006,
but hydrogen bonding between molecules produces extensive polymerization, and
the liquid and gas show large departure from ideal behavior. As a matter of fact
HF is the most imperfect gas studied.^ The physical properties of anhydrous HF
are shown in Table 5-1.
Fluorspar Properties
The preferred raw materials for the manufacture of HF in the United States
are acid grade fluorspar and sulfuric acid.. The physical properties of fluorspar
are shown on Table 5-2.3 The fluorspar is treated with sulfuric acid according
to the endothermic reaction:
Ca F2 + H2SOu * Ca S0i» + 2 HF
The reaction is believed to take place in a sequence of steps3
Ca F2 + H2 SO,, -* Ca (HSO^.F.HF)
Ca (HSO^.F) + HF -»• Ca SOu + 2 HF
The ability of the reaction to proceed to the maximum degree in commercial
operation is influenced by the purity and fineness of the fluorspar, the tempera-
ture of the reaction, the time allowed for completion of the reaction, and the
intimacy of mixing of the acid and spar.
-17-
-------
TABLE 5-1
THE PHYSICAL PROPERTIES OF ANHYDROUS HYDROGEN FLUORIDE1
formula, weight (calculated)
molecular weight
saturated vapor, at boiling point
saturated vapor, at 100°C
boiling point, at 1 atm
melting point
density
liquid, at 25*C
vapor, saturated, at 25 °C
vapor pressure, at 25°C
heat of vaporization
boiling point, at 1 atm
heat of fusion, melting point
heat capacity, constant pressure
liquid, boiling point
vapor, at 25°C, 1 atm
heat of formation
ideal gas, at 25*Ce
free energy of formation
ideal gas, at 25 °C*
entropy, ideal gas, at 25 "C*
critical temperature
critical pressure
critical density
viscosity, at O'C
surface tension, at boiling point
refractive index, 5893 A, at 25 "C
molar refractivity (5893 A, formula wt)
conductivity, at O'C
dielectric constant, at 0°C
dipole moment, EF molecule
20.006
7S.24
49.08
19.51°C
-83.37'C
0.9576 g/cmj
3.553 g/liter
17.S psia
J1609cal/20.01 g
(1785
46.93cal/g
12.2cal/(20.01 g)(°C)
143cal/(20.01 g)(°C)
-64.9kcal/20.01g
-65.0Iccal/20.01 g
41.5cal/(20.01gX°C)
ISS'C
941 psia
0.29 g/cm'
0.26cP
8.6 dyn/cm
1.1574
2.13cm1
<1.6 X 10~« mho/cm
S3.6
1.S3D
* From vapor pressure vs temperature.
* From ealorimetry.
' The enthalpy change for the reaction HF (ideal gas) — HF (real gas), at 2d°C, 1 atm, i.s
certain, and may exceed several kilocalories per mole (20).
-18-
-------
TABLE 5-2
THE PHYSICAL PROPERTIES OF FLUORSPAR (CaF2)
Molecular weight - 78.08
Melting point 1418°C
Boiling point 2513°C
Density - 3.18 g/cm3
Solubility of CaFo in Water
Cms. CaF? per liter sat, sol.
t°C
t°C
(flurospar)
(fluorspar)
(calcined)
(fluorspar)
(ph - 6.4)
(fluorspar)
Cms. CaF2 dissolved per 3LQO cc. in aqueous
0.5 Normal CH -£OOH. 1.0 Normal CH-£OOH. 2.0 Normal CH;COOH.
0
15
18
18
18
25
25
25
40
Solubility of CaF? ±
0.013
0.015
0.016
0.01S
0.015
0.018
0.016
0.040
0.017
n Acetic Acid
40 0.0153
60 0.0178
80 0.0206
100 0.0229
0.0175
0.0203
0.0237
0.0264
0.0192
0.0229
0.0267
0.0300
Solubility of CaF^ in Hydrochloric Acid at 25°C
Normality
of aq. KC1
0.01
0.10
1.00
Gm. moles
Dissolved per liter
0.00087
0.0053
0.0280
Heat of Formation (Solid at 298°K - 290.3 Kcal/g mole)
Heat of Fusion - 7.10 Kcal/g mole
Heat of Vaporization - 83.0 Kcal/g niole
Entropy at 298°K - 16.4 eu.
-19-
pH of
sat, sol.
2.02
1.05
0.04
-------
5.2 Typical Hydrofluoric Acid Manufacturing Process
In reviewing the HF manufacturing process, a typical process schematic will
be discussed first, followed by four major variation of the process. The initial
intention was to present a process schematic for each plant and describe its
process. However, since some companies consider their process description and
schematic confidential, this was not feasible.
The first step in HF manufacturing is spar drying. Most of the plants
import acid grade spar from Mexico, North Africa or Italy. The spar is received
in the particle size needed for reaction and can be wet (10% moisture) or dry.
Almost all plants have spar drying facilities. Spar dryers are usually rotary
kilns internally heated and some employ an independent cooling kiln with a heat
recovery system.
Sul'furic acid, a second raw material for HF manufacturing, is frequently
manufactured at the same facility.
The schematic of a typical•HF manufacturing process is shown in Figure 5-1.
This process schematic applies in general to most HF manufacturing facilities.
In recent years almost all HF is manufactured, in anhydrous form; 70% acid is
manufactured by dilution of anhydrous HF with water. The process schematics 6.2
showing the manufacture of 80% acid in strong acid absorbers and 50% H? in weak
acid absorbers are becoming obsolete.
The reaction between spar and sulfuric acid in the kiln is endothermic and
in most cases heat is supplied to speed up the reaction. To effect a release of
over 98% of fluorine in the spar the reaction time is normally 30-60 minutes at
200-250°C with HF leaving the reactor at 100-150°C.
-20-
-------
Since fluorine values dominate raw material costs, these factors are
optimized to give the T-aximum yield of hydrogen fluoride.
Acid-grade fluorspar is a finely ground flotation product having the
following typical specifications:
Screen analysis: 325 mesh. 1% on 100 mesh, 12% on 200 mesh, 30% on 250
niesh, 45% through
Car2 minimum 97.5-98%
Si02 maximum 1.0%
S maximum 0.05%
H20 maximum 0.1%
CaC03 principal remainder
Silica is a highly objectionable contaminant, since each pound consumes 2.6 Ib.
of fluorspar and 3.3 Ib. of sulfuric acid by the reaction:
Si02 + 2 CaF2 + 2 H2S01+ - SiF^ + 2 CaSOi+ + 2 H20
When hydrogen fluoride containing SiF^ is absorbed in water, a further loss
of fluorine values occurs by the reaction:
SiFt, -f 2 HF (aq) -* H2SiF6(aq)
Carbonates are harmful in consuming sulfuric acid, in producing foaming in
the generator, and in contributing carbon dioxide to the gas stream where
it acts as a noncondensible dilutent to the hydrogen fluoride. Sulfur-bearing
minerals in fluorspar (e.g., galena, pyrites) may generate hydrogen sulfide
or sulfur dioxide, contaminating the hydrogen fluoride, and sometimes
causing deposits of sulfur in the gas-handling equipment.
-21-
-------
Table 5-3 gives an extensive list of fluoride reactions many of which can take
place in HF manufacturing.
TABLE 5-3"
Reactions of Fluorides
Formation of Silicon Tetrariuoride In An Acid Medium
I.
2.
3.
4.
5.
6.
7.
8.
CaF: 4- HrSO, = CaSO, 4- 2 HF
4 HF 4- SiO: = SiF, 4- 2 H,0
6 HF 4- SiO, - H,5iF« 4- 2 H,0
H,SiF. = Sir. 4- 2 HF
Formation of Silicon Tetrafluoride in Thermal
Processes
Na-SiF. = 2 NaF 4- SiF,
CaF, 4- 1/2 Si03 = CaO 4- 1/2 SiF.
CaF: 4- 3/2 5:0: = CaSiO, 4- 1/2 SiF.
CaF: 4-1/2 CaSiO, = 3/2 CaO 4- 1/2 SiF.
Reactions of Silicon Tetrairluoride With Water
3 SiF, •+• 2 H,0 = 2 H,SiF. + SiO,
SiF. (g) 4- 2 H;0 (g) = SiO, <») 4- 4 HF (g)
Formation of Boron Trifluoride
11.
6 CaF,
B-0, = 4 BF, 4- 3 Ca, B, 0,
Formation o-f Hydrogen Fluoride By Hydrolysis
12.
13.
H.
15.
16.
17.
CaF, 4- H=0 = CaO 4- 2 HF
2 .NaF 4- H,0 = Na=0 4- 2 HF
2/3 A1F, 4- H,0 = 1/3 Al.O. 4- 2 HF
CaF, 4- H;0 4- SiO, = CaSiO, 4- 2 HF
CaF, 4- H;0 4- Al.O, = Ca (A10,)s 4- 2 HF
.\a>AlF. 4- 2 H;0 = Na A10, 4- 2 .NaF 4-4 HF
Formation of Volatile Metal Fluorides
18.
19.
20.
CaFr 4- Na.-SiO, = CaSiO, 4- 2 NaF
CaF, 4- K;SiO. = CaSiO, 4- 2 KF
CaF, 4- Na, CO, 4 SiO.. = CaSiO, 4- CO, 4- 2 NaF
CaF, 4- 4/3 A1;O, = Ca(A10j, 4- 2/3 AlF,
-22-
-------
The ratio of ^SO^ to CaF2 is seldom stoichiometric, since, depending upon
.the relative cost of the two, one is used in slight excess. Recent practice has
been to use excess acid. Almost all plants use externally heated horizontal
kilns with spar fed continuously at the forward end by a screw conveyor. Acid is
also added at the forward end of the kiln, and anhydrite is removed through an
air lock at the opposite end. The anhydrite is then either slurred and transferred
to system pond or recovered in the solid form. The gases emanating from the kiln
are removed at the front end of the kiln. The gases consisting of HF, H20, SC>2,
SiFi,, S02» H2S01+ and particulate are'first, treated in a precondenser or scrubber.
The purpose of the precondenser is to remove particulate, water and sulfuric acid
and to cool down the gas stream. The HF vapors are subsequently condensed in two
refrigerant-chilled shell and tube condensers. The crude condensed HF represents
almost 98% of production. It flows to intermediate storage tanks and is later
distilled. The uncondensed gases from condensers enter a fresh l^SOi^ absorption
tower. The gas stream leaving the acid absorber contains most of the SiF4 and
enters two water scrubbers where fluosilicic acid is recovered. The gases are
then vented into the atmosphere or are introduced into a caustic scrubber. The
driving force for gas movement through the absorption train is provided by an
ejector.
The total pressure drop across the HF absorption train is 15-20 inches W.G.
The kiln is kept under negative pressure of 1/2 in W. G.
The crude HF obtained from the two condensers is distilled in two distillation
columns to a purity of 99.98% making it the purest chemical in regular commercial
distribution.
-23-
-------
HF, S02. SiF4, C02
SiF«. S02, C02. HF
j. S02
Oleum
Sulfuric ac
r
,
Ui
Makeup
id i
Pfeconoense
+
J
c?
in
04
X.
8*
u?
0*
O
x~
u.
Kiln
L
u
c
d>
§
K
-M
1
s
c
u
TO
-------
5.3 Major Variations of Hydrofluoric Acid Manufacturing Processes
Since it is not possible to present a specific HF manufacturing process
schematic and description for each individual plant, four major process variations
will be described. Only open literature information was used to describe these
variations. Three plants were visited in the course of this screening study:
Allied Chemical plants in Baton Rouge and Geismar, Lousiana and DuPont plant in
La Porte, Texas. Reports of trips to these plants contain some confidential
information and are not present in this report. The visit reports are a part of
the EPA's confidential files.
a. Buss Process"
Figure 5-2 shows the process flow sheet for HF manufacturing using Buss
technology. Since the process is almost identical to a typical HF process described
in paragraph 5.2, only specifics of the process will be discussed.
One of the special features of this process is the use of a premixer called
Ko-Kneader developed by the Buss Co. of Basle, Switzerland.
-25-
-------
Figure 5-2 Process Flowsheet for the Manufacture of Hydrofluoric Acid3
Using Buss Technology
1. Premixer (Ko-kneader)
2. Rotary kiln
3. Precondenser
4. Primary scrubber
5. 1st condenser
6. 2nd condenser
7. Storage tank
8. Absorption tower
9. 1st weak acid scrubber
10. 2nd weak acid scrubber
11. Storage tank
12. Exhaust fan
13. Rectifying column
14. Distillation column
15. Storage tank
-26-
-------
The incorporation of the Ko-Kneader provides a series of important advantages over
conventional HF processes, namely:
1. 3y zo.iducting the first, most corrosive portion of the reaction
in a relatively small piece of equipment (about 6-ft. long by
1 ft. in diameter as compared with the 55 by 8 ft. reaction
kiln), the initial investment and replacement cost of corrosion-
resistant-alloy parts is kept low and the parts are physically
easy to replace.
2. The thorough mixing of sulfuric acid and spar accelerates the
subsequent reaction in the kiln, increasing plant capacity as
.much as 30% for a given kiln size.
3. A much smaller excess (or even stoichiometric amounts) of
sulfuric acid can be used, 'since separation of the two components
is no longer possible after leaving the Ko-kneader and a local
shortage of sulfuric acid is avoided. This results in better
quality HF and in an anhydrite quality suitable for further
processing.
4. Due to the perfectly homogeneous mixture of sulfuric acid and
spar substantially lower temperature can be employed in the
kiln, whereby: (a) the sulfuric acid has a lower vapor pressure
and contaminates the HF stream to a lesser extent and (b) the
kiln is subjected to much less chemical attack.
The other specific feature of the Buss process is that it results in a by-
product anhydrite and not in the gypsum pond slurry used in most other processes.
Figure 5-3 shows an anhydrate recovery flowsheet.3
-27-
-------
w
ACCELERATOR
'DRITE-
?OM K1LN~
LIME
r 1
j
L
' r
L
_^ MILL ID—* CU
OVERSIZE
^SSIFIER
T r
SILO
ANHYDRITE TO
BAGGING
Figure 5-3 Anhydrite Recovery Flowsheet3
-28-
-------
The anhydrite leaves the kiln through a seal screw. It contains a
small amount of unreacted sulfuric acid which is neutralized with lime.
An accelerator is added and anhydrite is ground to the standard commercial
fineness. The anhydrite can be marketed as a high strength building material
or a soil conditioner.
Three plants are believed to use the Buss process.
-29-
-------
b. Typical Process7
Figure 5-4 shows a schematic of an Exemplary Process used by EPA in the
study for effluent limitation guidelines and New Source Performance
Standards. It is believed that four or five plants use this process.
The flow diagram is similar to that for the Buss Process, major differences
being that no premixer is used and that anhydrite is slurried and transported
to the gypsum pond. Another difference is that fluosilicic acid is not
recovered in this process so lower SiC>2 content can be tolerated in
spar. It might also result in SiF^ emissions. All HF is recovered as
anhydrous in both the Exemplary and Buss Process. The tail gas emission
volume from this process is considerably lower than that from the Buss
Process.
c. Aluminum Fluoride Manufacturing Process
Aluminum fluoride is one of the major products in which HF is used as a
raw material. In a typical A1F3 process gaseous HF emanating from the
kiln is contacted directly with hydrated aluminum in a fluidized bed
reactor. Some plants use all HF together with impurities for A1F3
production, while other isolate a portion of gaseous HF as anhydrous
using an absorption train similar to that used in a typical process.
In the case when all HF is used in gaseous form for A1F3 production, it
is questionable if it can be considered an HF manufacturing plant. In
such case only two steps used in a typical HF manufacturing plant,
namely spar drying and its reaction with H2S01+ in the kiln, are utilized.
It is believed that at least three plants utlize this process.
-30-
-------
d. Patented Process
In the patented process fluorspar is reacted with a mixture of sulfuric
acid, sulfur trioxide, and water vapor at a temperature low enough
to allow liquid 11230!+ to condense on and to react with CaF2 but high
enough so that CaF2 particles do not become sticky. The temperature
of reaction can be closely controlled and the resulting anhydrite can
be readily withdrawn from the reactor. The heat for reaction (between
spar and I^SO^) is provided through reaction of steam and 863. An
additional benefit of this process is that the use of heat transfer
surfaces and attendant problems! has been eliminated.
-31-
-------
I
U)
NJ
FLUORSPAR
GAS FUEL
AND AIR
THREE
,""7"
PARALLEL
RESIDUE
CaSQ4 TO
TRENCH AND
RECYCLE
FIGURE 5-4
EPA EXEMPLARY HYDROFLUORIC ACID PROCESS FLOW DIAGRAM
CONDENSER
DISTILLATION
COLUMN
TO PURE
PRODUCT
COOLING
-o.
SEWER
-------
5.4 Recovery of Fluoride Value From Phosphate Rock
Most phosphate rock used in the manufacture of phosphate fertilizer con-
tains 3-5% fluorine in the form of the mineral fluorapatite (Ca3 (POI+) sF) . When
this rock is treated by either acid or thermal processes, fluorine is released
as SiFu. Many studies to produce HF from this source have been made9 but two
hurdles exist:
1. SiFi+ cannot be conveniently converted into HF.
2. Collection of SiF^ for an economic capacity is expensive. A proposed
process10 starts by reacting silicon tetrafluoride with recycled
ammonium fluoride solution to form ammonium flousilicate.
SiFt, + ZNH^F -»• (NHt+)2SiF6
When this solution is neutralized with ammonia, silica precipitates and
more ammonium fluoride is formed.
(NHtt)2SiFs + 2 H20 + 4 NH3 •->• Si02 + 6 NH^F
The ammonium fluoride solution (except that recycled) is evaporated to a
salt concentration of 94-95%, when some conversion to ammonium bifluoride,
NH1+HF2, takes place by vaporization of ammonia. The evaporation continues until
a salt concentration of 98% is reached, when the mixture solidifies at about
100°C. The solid mixture of ammonium fluoride and bifluoride, containing 60% of
fluorine, is decomposed with 93-95% sulfuric acid at 180-190°C. Ammonium bisul-
fate is the principal component of the residue; this can be converted to ammonium
sulfate by neutralizing with ammonia.
The economics cf this process depend on a low-cost supply of silicon tetra-
fluoride, a premium market for precipitated silica (proposed, for example, as
reinforcing pigment for rubber), and a local market for ammonium sulfate. The
process is handicapped by a large filtration and evaporation load.
-33-
-------
The alternative way to recover the fluoride value from phosphate rock is to
use waste fluosilicic acid. H2SiF,5 is formed in the phosphate fertilizer
plants' scrubber towers in which SiF^ hydrolyzes:
3 SiF^ + 2 H20 -> Si02 + 2 H2 SiF5
Two procedures to recover HF from H2 SiFg can be used.11 The first
procedure is direct hydrolysis of H2 SiF$ according to the following reactions:
H2 SiF5 + 2 H20 ->• SiOp + 6 HF
The reaction is carried out when H2 SiFg is volatilized in a flash
vaporizer and the vapors are passed through a quartz tube externally heated
to 1000°C. A water cooled copper condenser is used to recover HF.
The results of a laboratory study showed that direct hydrolysis at
elevated temperatures was subject to many mechanical difficulties, and
that corrosion of construction materials was a serious problem. Elimination
of Si02 from the HF product was generally poor.
The second procedure, showing more promise, is hydrolysis of lime -
neutralized H2 SiF5. Neutralization proceeds in two steps:
H2 SiF6 + Ca (OH)2 * Ca SiF6 + 2 H20
Ca SiF6 -t- 2 Ca (OH)2 - 3 CaF2 + Si02 + 2 H20
More Si02 is needed to satisfy the following reaction:
CaF2 + Si02 4- H20 -* Ca Si03 + 2 HF
The apparatus used for hydrolysis of lime - neutralized H2 SiFs is
shown in Figure 5-5.il
To operate the system, a charge of 2 1/2 to 3 kilograms of pellets
is placed in the reactor tube, forming a bed about 16 to 20 inches deep
in the zone of maximum heat. The reactor and flash vaporizer are brought
up ro temperature; the vaporizer is heated to 450°C and the reactor heated,
-34-
-------
Condenser
Cooling
water
Product
receiver
Cooling water
0000
Plenum
heater
FIGURE 5-5 - Vertical Hydrolysis System
-------
for aost of the tests, to 1,000°C, measured at the outside surface of the reactor
tube. When operating temperatures are attained, the flow of water was started to
the vaporizer at the desired rate. This causes a temporary drop in the vaporizer
temperature, but recovery is usually complete within 15 minutes. The condensed
HP product is collected in a polyethylene container. Samples are taken periodically
and analyzed for fluorine and SiC>2 content. The test is usually terminated when
80 to 90 percent of the available fluorine lias been removed from the reactor
charge and the solution becomes increasingly dilute.
Reaction characteristics of steam-hydrolysis of lime-neutralized H£ SiFg are
as follows:
1. Addition of 70 to 100 percent of the calculated Si02 requirement has
little effect on hydrolysis rate or HF concentration.
2. The HF concentration increases with increasing reaction temperature
over the investigated range 950° to 1,100°C.
3. The HF concentration increases with decreasing water feed rate.
4. The Si02 content of the condensed HF product does not exceed 1.8 per-
cent of the fluoride content, and is usually much lower.
The conclusion of the survey of processes for HF production from phosphate
rock is that they are still in the early stages of development. It will probably
take decades before such processes can be developed into a full scale production.
HF manufacturing e from spar will probably remain the most economical process
for years to come.
-36-
-------
5.5 References
1. Hydrofluoric Acid, Kirk-Othmer Encyclopedia of Chemical Technology 2nd
Ed. p:610-625, 1964.
2, Simons J.H., Fluorine Chemistry Volume 1, p. 230, Academic Press
Inc., Publishers, New York, N.Y. 1950.
3, R.ogers, W.R., Muller, K., Hydrofluoric Acid Manufacture Chem. Eng.
Prog. Volume 59, No. 5, p. 85, May 1963.
4., Semrau, K.T., Emission of Fluorides From Industrial Process - A
Review. JAPCA, Volume 7, No. 2, August 1957, p. 92-108.
5., Faith, W.L. etal., Industrial Chemicals, Third Edition, John Wiley &
Sons, Inc., 1965, p. 428.
6. Helier A.N., etal., Inorganic Chemical Industry, (In: Air Pollution,
Volume 111, 2nd Ed., Stern A.C./ed.), New York, Academic Press, Inc.,
1968, p. 197-198.
7. Development Document for Effluent Limitations Guidelines & New Source
Performance Standards for the Major Inorganic Products Segment of
Inorganic Chemical Manufacturing Point Source, EPA Report No. 440/1-74-
007a; NTIS PB-238 611.
8. U.S. Patent No. 3, 102, 787, Preparation of Hydrogen Fluoride.
9. Tarbutton, W.R., etal., Ind. Eng. Chem. 50, 1525-1528 (1958).
10. Boguslavskiy, S.N., etal, Khim Prom, 1961 (7), 6-8.
11. Good, P.C., Tress, J.E., Recovery of Hydrofluoric Acid for Waste
Fluosilicic Acid, Bureau of Mines Report of Inv. 7213, 1968, 14 p.
-37-
-------
6.0 EMISSION SOURCES AND RATES IN HF PRODUCTION AND MANUFACTURING
6.1 Sources and Nature of Point Source and Fugitive Emissions
There are very few sources of air emissions in a HF manufacturing plant.
The major sources and pollutants can be divided into three categories:
1. Spar drying and handling
Spar is received by barges and tank cars and is unloaded into stor-
age areas or silos. In addition to the main storage silo(s), most
plants have a separate spar use silo which normally contains one
day's supply. Spar unloading results in fugitive emissions which can
be substantial under windy conditions. If spar is stored outdoors
in a stack, this is a potential source of fugitive emissions.
The main emission of spar occurs during the spar drying. The gas
volumetric flow rate from the dryer is in the order of 2,000-13,000
ACFM. The emission consists of spar as a fine particulate and com-
bustion gases since the rotary kiln dryers are most frequently inter-
nally fired. Both natural gas and No. 2 fuel oil are used for firing
so that SOo, NO , and CO can be present in the emission stream. The
emissions from the dryer are controlled with bag filters; only one
plant uses a high energy Venturi scrubber. Dry spar is stored in
silo(s) which are, as a rule, also controlled with a bag filter,
frequently the same one used for control of the dryer.
2. HF manufacturing
Almost all HF-producing facilities have only one point source from
HF manufacturing (consisting of kiln and absorption train). Since
the potential pollutant HF is the desired product, it is in the best
interest of the plant to recover all HF. Consequently, HF gas is
precooled, removed in refrigerant cooler, treated with sulfuric acid,
and finally scrubbed with water. The emissions in the tail gas (after
the final scrubber) contain small quantities of HF, SiF^, and S02.
The amounts of these compounds depends on the process and its varia-
tion.
a. Buss Process
In this process, a caustic scrubber is usually employed as a
final control step. Since fluosilicic acid is recovered in
this process, most of the SiFu is removed before entering the
final scrubber. Caustic should have 99% efficiency in remov-
ing HF.
-38-
-------
b. EPA Exemplary Process
The process described as the EPA Exemplary Process uses different
scrubbing media in a final scrubber. Depending on whether the
scrubber liquid is acidic gypsum pond water, plain water or
caustic solution, the efficiency can vary from 70% to 99%. Since
fluosilicic acid is not, as a rule, recovered in this process,
SiFu may be a major pollutant. The emissions might be parti-
cularly high when acid scrubbing is used and when spar contains
high percentages of SiC>2 (over 0.5%) The tail gas volumetric
flow rate in this process is smaller than in the Buss Process
and runs in the order of hundreds of ACFM. A typical tail gas
exhaust stack is shown in Ilgure 6-1. There is a possibility
of HF emissions from acidic pond water; this will be discussed
under water pollution in Section 6.4. The emissions from spar
handling and drying are similar to those trom tne auss Process.
c. A1F3 Manufacturing Process
There is no tail gas in this process if all HF is used for A1F3
production in a fluidized bed reactor. When HF isolation is
used, emissions are similar to those from the Exemplary Process.
Spar handling and drying emissions are similar to those described
for the other processes.
d. Patented Process
In this process the tail gas is scrubbed with limed water, so
low HF emissions are expected. SiF^ emissions could be high
since fluosilicic acid is not recovered. S02 content in the
tail gas could be high because of S02 evolution in the reactor.
Spar handling and drying emissions do not vary from the other
processes.
In addition to tail gases, reaction kilns are potential sources of HF
emissions. Normally the kiln operates under negative pressure but, under upset
conditions caused by a plugged absorption train or incorrect spar-^SO^ ratio,
it can emit HF. Many plants have an emergency scrubber or a bypass to the final
scrubber which is operated under upset conditions.
3. HF Handling and Other Fugitive Sources
Almost all HF isolated in manufacturing is in the anhydrous form. If
70% is Che desired product, it is obtained by mixing anhydrous HF with
water. The HF emissions from this source are frequently controlled by
a wet scrubber using pure water as a scrubbing liquid.
-39-
-------
Anhydrous and aqueous HF is stored in the storage vessels and trans-
ferred to tank cars or trucks for transportation. If not properly
controlled, the loading process is a possible source of fugitive
emissions. At least one plant was found where this was a major source
of intermittent HF emissions causing complaints from the neighbors.
Leaks throughout the HF plant can be another source of fugitive
emissions caused by the corrosive nature of HF. HF plants have an
unusually high ratio of maintenance to operating personnel and good
maintenance was pointed out as a key to successful HF manufacturing.
A significant unknown in HF plant ?ir emissions is the gypsum pond.
In cases when pond liquid is acidic, it could be a source of fugitive
HF and SiF^ emissions.
6.2 Controlled and Uncontrolled Emission Sates
As a first step in the determination of emission rates from HF manufactur-
ing, TRC obtained printouts for all eleven HF manufacturing facilities in the
National Emission Data System (NEDS) and the Compliance Data System (CDS). Both
computerized data bases were of little help in this project. NEDS contains
little quantitative data most of which is out of date and unreliable. Most
quantitative information is listed as confidential and cannot be presented in
this report. CDS contained no quantitative information.
Figure 6-2 shows a schematic of HF manufacturing indicating major emission
streams and emission rates. This process model assumes that the only HF fluoride
emission stream is tail gas. No spar emissions from the dryers have been esti-
mated in this model but another study5 indicates that maximum emissions after
control would not exceed 20 Ib/ton. The emission factor ranking shown in
Table 6-1 is relatively low indicating that these factors must be considered
Questionable.
-40-
-------
te&JSSJF'&r^&l-'-'-i.'*' '—.""' •'•- •"- '• : ••--. '...•-.
:
•••-;^v%^"\>j-i^>--^r ••'•
_-• -\:i,^.:-,x.v?i-Si.-:..^...".-...7>. -.
Figure 6-1: Typical Tail Gas Exhausc Stac
-41-
-------
SIHMIKK'
ACIU(»4X.V
AHIIMI i »0% AIIIIYDIOtii IIF,
Jj'j. tACH Of 50% ANli »0»,i llf
• hit AUiulHlGll iYSItM IliUAtlY
COHlAlin / lOV/fIS, 5 Wl'/K ACIU
AMO V SI«ONl'> ACID AOSOkltKS.
II,M>4 HtlYLH
IJO'f
COMVmlK)fMI KtlllE-IYrt
lit ill! II OClllAIlNG AI
J40-I-.
• lYfll'AI fA«llClf SIU;
iv on i oo /.if si i
u* on iooMisii
30% ON 2iOMfSM
4}% IIKU iiSMlSII
ACID C-IAlt
riuoiscAf
" 1 30 10 tO
J MIN AI 400-1
'"" in mm
iiiisi m AIM. UIHING CAICUIM
MOVtMtMl OfrOWDCHtO SUlfAIE
IfSILllIt
IIYDIIOflUOIdC
AClu (liO'X.1
OA'.li - 2!i 10N1/DAI llf CHOUUtllON (AiiUKS WI AJIIKUWIUS IIF. Zil tACII Of Ult Mill UOl HI)
-LUS/IIH
III
sit,
lot.) lluorld.!
luUI .> 1
C.CO
j
Slllj
Ii^io4 (itJ)
t^o4
^
'\'"
liix-l
A(>|iio«. lot*!
UPC--.
~^~ -•--•-" - ' * ---' •- L n *•
1
4KW(i»|l)
4100
tiaa
40(A)
40<*>
.(AI
'
4i'uO
:
b400
i.400
3
„,>,""
20
III
211
,,„,„„,
4
I,
7»Ut Kill
.-
i""
w
40
M
M
7100
;luo
»
41-1 (II
blO
*M _
111)
640
/
SID |l|
bill
41X1
'.,111
101 III
8
4UII
4UO
K
/.. (,>""
» (,)""
1.0
10
•M9>
J(ij)
un
lu
hilo(t)
lulu
VIII
linn
•Cjseoui effluent itream
(A) Impurities in the fluorspar feeJ.
(B) Ihtf calcium sulfdte residue itreara uny liberate fluorides. Literature
search revealed nu data.
(C) References 2, 3
(0) Reference 4
Soluble fluoride evolution fatlor. •= 52 Ib r/lon llf
(s) Solid
(g) Caseous
Figure 6-2: Uydrof luorit: Acid Production - Uucont roJ 1 tul Process Model1
-------
TABLE 6-1
EMISSION FACTOR RANKING FOR HYDROFLUORIC ACID1*
Emission Data Process Data Engineering Analysis Total
0-20 0-10 0-10
35 3 11
-43-
-------
The soluble fluoride emission evaluation factor is 52 Ib F/ton HF. It
must be mentioned here that there are problems in evaluating fluoride emissions
by available sampling methods. If Method 13 is used as a means of determining
fluoride emissions, both gaseous and solid fluorides would be measured. It
appears that any evaluation of fluoride emissions should also include the spar
stream.
Figure 6-3 shows the controlled process model in which the tail gas is
scrubbed. The soluble fluoride emission is estimated to be 4.1 Ib F/ton HF.
Fugitive emissions have not been estimated but indications are they might
be high. The State of Louisiana regulatory agency Emission Inventory Question-
naire shows that fluoride fugitive emissions are of the same order of magnitude
as controlled ones. One indication of fugitive emissions is ambient fluoride
concentration. The Texas Air Control Board sampled HF property line ground
levels at one location and discovered that plant downwind HF concentration is
2-10 ppb higher than upwind.
6.3 Annual Emission Rates and Plant Inventories
Table 6-2 shows the annual estimated soluble fluoride emissions from HF
production. The basis for calculations is available emission factors and an
expected annual growth rate of 6%. This projected growth rate is undoubtedly
much too high since the production capacity for 1977 is about the same as it
was in 1970. The projected production for the year 1982 obtained from industry
shows that no growth is expected.
Table 6-3 shows the emission inventory for HF manufacturing plants. An
attempt was made to develop emission factors based on a plant's emission inven-
tory but data are too scarce, variable, and are too unreliable to draw valuable
conclusions.
-------
WATER-
ISO'F
-TO STACK
SPRAY SC3UB3ER
EFr. * 90% GASEOUS
TO NEUTRALISATION
AND DISPOSAL
BASIS - 25 TONS/DAY HF PROCl'CTION
(ASSUMES 1/2 ANHYDROUS HP. 1/4 30? HF AND 1/4 301 HF PRODUCED)
PROCESS STREAMS - U3/HR
Mate rid Is
HF
Sir",
Total rluoric!es
Total as F
coz
H2a
Accra*. Total
Strgira
Stream Muroer
9
2S(g)
34(g)
SO
SO
16(g)
3(9)
ao
n
Z«(9)
JHg)
55
46
z.s un(A)
60!A)
12«
2(3) (Est.)
3(g) (cst.)
S
4
'S(g)
Q.S(g)
20
'Gaseous effluent Stream
(A) Plus scrjbbing water.
(3) Ajjunes 100; usage of scrubbers an all facilities.
Source
Scruoaer
Assuned Fugitive
*_
Total Emission
Saluole Fluoride Emission
Factor - lb F/ton HF
4.5
0.0
4.1
1
Overait soluole
se amssion . 4.] :b F/ton HF
(3)
Figure 6-3: HF Production - Controlled Process Model1
-------
TABLE 6-2
SOLUBLE FLUORIDE EMISSIONS FROM HF PRODUCTION1
(Based upon a 6% annual growth factor)
HF Production
(105 tons/year)
Soluble Fluoride
Evolution Factor
(Ib F/ton HF)
Soluble Fluoride
Emission Faccor
with Current Practice
(Ib F/ton HF)
Soluble Fluoride
Emission Factor with
99% Control
(Ib F/ton HF)
Soluble Fluoride
Evolution
(103 tons F/year)
Soluble Fluoride
Emission with
Current Practice
(103 ton F/year)
Soluble Fluoride
Emission with
99% Control
102 ton F/year)
1970
0.34
52
4.1
8.84
0.70
2000
2.60
52
4.1
0.52
67.6
5.33
0.68
-46-
-------
TABLE G-J
EMISSION INVENTORY FOR IIP MANUFACTURING IM-ANTS
I11.ml
Allle.l
Alcoa
Sl.lllf fOIO
N.I
Clcvolnnil
Oil
i;,i|i.i< lly
1975 O.itL-
Tlinilti.iml Toil!)
15
12
'.5
2(1
100
55
18
50
25
II
IB
Km lea Ion Source
:i|i.if ill yi>r
in II K.MI
Ijp.ll Illl III. Ill
Soil.i auli iiiilunil
Sp;ir H! In
Til II P..1H
S|>ar inn* ullo
j|i«r Uryor
S|>.it si In
Tall ii''s
Spur nllo
T.I 11 I'.'IH
Spur diyi;i
S|>.il alia
-
Spiir lonillnK
Sp;ir fugitive
111 own r fugitive
4 gencr.itorti
fugitive
S|>ar Jiyoi
Spiit allu
Sp.ii unlo.iil Ing
Spur ilrycr
Hall mill
UK kiln
S|i»r ilryor
T.il 1 (',,iu
('out ml
N.'iftlioii'ic
Wi-t in rnl>lier
Hll|*llOII!IO
Wui uciulil>or
ll.lgllOIISO
Sriul>liil">llnlioii.'ie
Wot lii-ruliber
Hni'.liniiNe
Si:rublior
Bngli(iii!ie
BlIgllDIISl'
-
n.'ii'jiouHK
n.iglintiso
-
Bnghii'ini'
Haglioiuif
-
Oni'liiiiific
Srnililii-r
ACIH
5,000
160
-
l.fiOO
170
l.f.OO
fl.900
85
750
-
J.787
1.8)6
-
11,220
1 . 260
-
9,OOO
-
-
J , OOO
'../ SO
Finjfluloii
Kiilc
Ili/lir
It
-
o.ot
120
21
0.6
0.8
21
6.5
0.1
0.8
1.8
!5
6.9
0.1
-
2.8
7.5
2.6
3.6
5.J
0.8
o.a
-
0.8
0.5
0.5
10
Pollutant
S|uir
S|i.n
Soila ash
Spur
S(»2
UK
Spur
Spnr
Spin
SIKS
SO;
Sj-.ijr
soa
F
-
Spnr
S|inr
IIF
F
Spur
NO
Spar
-
S|>nr
S|inr
UK
Spur
F
Kfl Irli-ncy
Z
')')
9')
99. ')
4(,
«)9
96-99
%-99
9'>
99
~
99
-
99
99
-
99
99
9'».5
95
-------
In conclusion, an emission of 20 Ib/ton of spar is realistic and in line
with findings during plant visits and contacts with the industry. An emission
of 4 Ib/ton of soluble fluorides also appears to be realistic.
6.4 Gypsum Pond Emissions
Most HF manufacturers slurry anhydrite and transfer it to gypsum ponds. The
gypsum ponds have been investigated in the phosphate fertilizer industry and
were found to be a significant source of fluoride emissions and a source of radio-
active isotopes which can be leached into aquifers. Figure 6-4 shows the waste-
water recycling used in an EPA Exemplary Plant6 where all process and scrubber
wastewaters are recycled. The waters used to slurry and remove anhydrite and
scrubber water are fed to a pond system after being treated with caustic or soda
ash and lime to precipitate fluorides and adjust the pH. In the pond system,
the insolubles are settled out and waters are then reused.
Table 6-4 shows waste products from HF manufacturing at the Exemplary Plant.
Only cooling water is discharged from this facility. Neutralization of sulfuric
and hydrofluoric acid wastes with lime, followed by removal of precipitated
CaSO(+ and CaF2 in settling ponds, reduces fluorides to 18 mg/1 and calcium sul-
fate to approximately 2,000 mg/1 in treated water streams. Lime treatment of
the isolated wastes and settling pond removal of precipitate reduces the fluor-
ine content of this small stream to approximately 10 mg/1. No fluoride emission
is expected from the gypsum ponds which are neutralized to pH 6-7. However,
contacts with HF manufacturing plants indicates that some ponds have a pH of
1. In that case, HF and SiF^ emission is possible. Measurement of fluoride
emission rate is recommended.
-48-
-------
SETTLING
POND
A
SETTLING
POND
A
CLEAR
WATER
POND
RECYCLE
WATER
PUMP
^NEUTRALIZED RESIDUE SLURRY
FURNACE
FURNACE
FURNACE
UIX-
D*
NEUTRALIZING
PIT
Figure 6-4: Effluent Recycle System at an Exemplary Plant6
-------
TABLE 6-4
WASTE PRODUCTS FROM HF MANUFACTURING PLANTS6
(Based on Estimates for the EPA Exemplary Plant)
Waste Product
Product
Process Source
Avg. kg/kkg (Ib/ton)
2.
3.
4.
5.
6.
7.
8.
CaSO;
CaF2
HF
H2SiF5
Si02
S02
HF '
Kiln (reactor)
Kiln (reactor)
Kiln (reactor)
Kiln (reactor)
Scrubber
Kiln (reactor)
Scrubber
Scrubber
3,620 (7,240)
110 (220)
63 (126)
1.5 (3)
12.5 (25)
12.5 (25)
5 (10)
1 (2)
Total Quantity
Type
Cooling
(river water)
Slurry and
Scrubber
cu in/day (gpd)
3,270 (864,000)
3,270 (864,000)
l/kk%(gal/ton)
90,140 (21,600)
90,140 (21,600)
Recycled
0 percent
100 percent
-50-
-------
6.5 References
1. Robinson, J.M., et al., Engineering and Cost Effectiveness Study of
Fluoride Emissions Control, p. 3-297, Vol. 1. February 1972, NTIS
No. PB 207 506.
2. Kirk-Othmer, Encyclopedia of Chemical Technology, Interscient Pub-
lishers, New York 1965, Vol. 9.
3. Gaith, W.L., Industrial Chemicals, J. Wiley and Sons, Inc., 3rd Ed.,
1965.
4. TRW Systems Group, Air Pollutant Emission Factors, Dept. of HEW,
Contract No. 22-69-119, NTIS No. PB 206-924, April 1970.
5. Rogers, W.R., Muller, K., Hydrofluoric Acid Manufacture, Chemical
Engineering Program 59:85-88, May 1963.
6. Martin, E.E., Development Document for Effluent Limitations Guide-
lines and New Source Performance Standards for the Major Inorganic
Products Segment of the Inorganic Chemicals Manufacturing Point
Source, EPA Report 440/l-74-007a, NTIS No. PB 238-611.
-51-
-------
7.0 CONTROL OF EMISSIONS FROM HF MANUFACTURE
Emissions from HF manufacture can be divided into three categories:
1. Particulate emissions from spar 'handling and drying
2. Gaseous emissions from the HF absorption train (tail gas)
3. Fugitive emissions from process, HF loading, and gypsum pond.
7.1 Particulate Emission Control
The largest source of particulate emission in HF manufacture is the spar
dryer. The secondary sources of spar are storage silos and transport of solid
materials. These emissions can be controlled with wet or dry gas cleaning
devices. Table 7-1 shows the advantages and disadvantages of both methods as
applied to a broad range of particulate matter.
Out of 9 plants, 8 are using the dry method applying cyclones and bag-
houses. A typical baghouse used in a HF manufacturing plant is shown in Fig-
gure 7-1.
Figure 7-2 shows a typical baghouse with pulsed air cleaning frequently
used in spar emission control.
In selecting the baghouse for spar control, the major parameter is air to
cloth ratio.
Figure 7-3 shows a kiln venturi scrubber system similar to one that can be
used on a spar dryer. In the selection of the wet scrubber for particulate
control, one should consider the following factors1*:
1. Particulate characteristics: physico-chemical properties
2. Carrier gas characteristics: temperature, pressure, humidity, etc.
3. Process factors: gas flow rate, particulate concentration, pressure
drop, etc.
4. Operational factors: floor space, materials of construction.
-52-
-------
TABLE 7-1
ADVANTAGES & DISADVANTAGES OF WET & DRY AIR & GAS CLEANING DEVICES1
ADVANTAGES:
DRY
1. Recover product dry
2. Freedom from corrosion
3. Less storage capacity
required for waste
4. Insoluble materials > 0.05 ym
may be collected with high
efficiency
5. Recirculation of treated gas
may be possible if the gas
is resoirable.
WET
1. Gases & particles col-
lected together
2. Soluble materials may
be readily collected
3. High temperature gases
cooled
4. Corrosive gases and mists
may be neutralized
5. Eliminate fire or explo-
sion hazard.
DISADVANTAGES:
DRY
1. Hygroscopic materials may
cake
2. Dust exposure to mainten-
ance personnel
3. High temperature; costly
construction
4. Not tolerate acids or cor-
rosive mists
5. Secondary dust disposal
problem
WET
1. May require recrystalli-
zation for soluble parti-
cles
2. Easily pumped but may need
sludge pond
3. Dissoluble particle recovery
requires liquid filter
4. Particles < 1pm not easily
collected
5. Freezing problems
6. Liquid entrainment in efflu-
ent frequent problem
7. Cleaned air may not be
suitable for recirculation,
high dewpoint causes condi-
tion.
-------
Figure 7-1: Baghouse for Control of Spar Emission
-54-
-------
rgFIM. DSC^ASGE
Figure 7-2: Typical Baghousa vita Pulsed Air Cleaning1
-------
Ch
I
CYCLONIC
SEPARATOR
FWCSH WATER OR
KILN COOLING
WATER
/RECYCLE
7-'3: Kiln Venturl Scrubber System3
-------
Figure 7-4 shows the relationship between collection efficiency and
particle size in Venturi scrubber.
Only one HF manufacturing plant uses a high energy Venturi scrubber for
spar control.
The review of control technology for spar emission shows that best control
technology is the use of fabric filters. The efficiency of fabric filters used in
spar control is about 99%. A high energy Venturi with a pressure drop of 20-40
in WG would have a comparable efficiency. The drawback of scrubbers is that they
do not recover spar in usable form and create wastewater problems.
7.2 Gaseous Emission Control
The major source of gaseous emission from HF manufacture is tail gas from
the absorption train. The major pollutants are HF, SiF^ and S02. The best
technique for control of these gaseous pollutants is absorption.
The absorption of tail gas is usually accomplished in a packed tower
shown in Figure 7-5. The tail gas is contacted with scrubbing liquid in a
counter current fashion.. To increase the mass transfer the tower is filled
with packing. The gas on its way from bulk gas to bulk liquid and to final
elimination has to overcome three resistances^:
1. Diffusion through gas phase film
2. Diffusion through liquid phase film
3. Chemical reaction rate.
Any one or a combination of the three resistances can be the rate controlling
step. Because of the great solubility of HF and SiF^ in water, the gas film
resistance would be expected to be controlling.
-57-
-------
0.2 aj a.4 a« a* j
••MTXU sar-
3 4 4 • • O
Figure 7-4:
Relationship Between Collection
Efficiency and Particle Size in Venturi Scrubbers
-58-
-------
Discharge
Liquid Inlet
Liquid
Spray Distributor
Gu
Initt
Drain
Figure 7-5: Typical Packed Tower-
-59-
-------
In such cases and with packed towers, it is usually found that5:
Kg ^ G0.8
Where Kga = mass transfer coefficient, Ib moles/(hr) (cu ft) (atn)
G = gas mass flow rate, Ib moles/ (hr) (sq ft)
Therefore,
where N_ = number of transfer units
Z = tower height, ft
Thus, the number of transfer units obtainable would be controlled by the height
of the tower. However, the number of transfer units usually increases as the
liquid mass flow rate is increased.
Table 7-2 shows HF absorption data in various wet scrubbers.6 An import-
ant consideration in pollutant removal is the performance of equipment. It
is sometimes difficult to compare the performance of two basically different
types of equipment in terms of mass flow rates, height of transfer unit or
mass transfer coefficients. The performance of equipment has been studied in
terms of the number of transfer units. The effect of liquid and gas flow rates
is expressed in terms of theoretical power consumed per unit of gas flow rate,
as power consumption as such is usually of more economic concern than liquid or
gas mass flow rate. Such relations are mainly a matter of convenience and do
not necessarily have a theoretical basis. Figure 7-6, 7-7 and 7-85 show the
relationship between number of transfer units and power consumption in absorp-
tion of HF, SiF^, and S02.
-60-
-------
Install*-
tion
A
B
C
D
E
r
G
Typ« of Equipment
Cross flow (pray
Cross flow spray
Couoterflow spray
Parallel flow spray
Counlcrflotf spray
Veoturi
Vrotnri
Absorbing
Liquor
Water
Lime water
Water
Lime watar
Water
Water
Water
G, Lb./(Hr.)
(Sq. Ft.)
2,110
1.8BO
2,080
1,830
1,400
2,050
2,000
13,800
2,000
76,000*
-70,000*
L. Lb./(Hr.)
-------
100 rr
10
Ul
-------
IUU
V)
t-
1 10
IT
LU
U.
v>
z
<
X.
u.
o
IE
IJ 1
CO '
Z
Z
0 1
— * 1 i t 1 1 1 i
. . . , rr
HYOffOGEN FLUOfflOe
- 9 Vtry* - n.m.lo..«t A
r— 3^ S{Kay* — rt4lnfluti0A 8
_ ^3 ^**«r« — «*ioil«io«i C
£j Sprqr* — ftfttallniioA 0
T^- Saror% • •t»tal!«fi«* E
~ (^) Veniyri * ittiallartM F
— O ^ •***«« - AYtolloftWI C
"" (5t "ti Call — RcfcrvncB 1
. J-J
HLI ««« Cell (HF * M<«t) . 3cf. 2
•• *•"*
HB
B
^
-
][
_
i : • i i i 1 1
*
a
O
u
o
i i 1 1 1 1 it
i I » 1 I J 1 I
SILICON TC
i i i i i 1 1 ^.
TR4FLUORIDE I
• C» ^. f^ /S^
£}t^*±s ~
/^*O O
^^ -™
v
-
-
~
_
i 1 1 1 1 1 1 1
O.OOI .0.01 0.1 1.0 1C
TOTAL POWER INTRODUCED - Hp/MCFM'
Figure 7-7: Power Consumed in SiFi+ Absorption
-63-
-------
IOO
_ 1 t- I 1 * t I I J I I i I 1 I i I t I I I I I I 1111(1
i t i 1 i > 11 I 1 t 1 ! I 11 i i i 1 i i i r ! i > i i • i i
0.001 0.01 0.1 1.0 10
POWER INTRODUCED IN GAS OR "LIQUID PHASE Hp/MCFM
Figure 7-8: Power Consumed in Absorbing S02
-------
The absorption of sulfur dioxide is analogous in many respects to the
absorption of gaseous fluorides, and the relative performance of equipment
should be similar. It was shown that the number of transfer units obtainable
on grid towers is controlled principally by tower height and is only slight-
ly affected by power expended on the liquid and gas phases. The performance
of cyclone spray scrubbers is primarily a function of power expended in the
liquid phase and is essentially independent of the power expenditure in the
gas phase. Performance of Venturi scrubbers, on the other hand, depends
largely on the power expended in the gas phase but is slightly affected by
liquid power expenditure. These results are useful in characterizing the
dominant factors in the performance of equipment used in the absorption of
gaseous fluorides.
Nearly all usable data from the absorption of hydrogen fluoride are based
upon application of spray towers. The performance of this equipment appears
to be dominated by the power expended on the liquid phase, as was the case with
the cyclone scrubber. Significant differences in performance among the various
spray towers in use were found. Wet-cell washers require a higher power con-
sumption than simple spray towers with the same performance.
The performance of spray towers absorbing silicon tetrafluoride is not
consistent with simple gas absorption. One possible explanation is that
mists are formed in the tower, which are collected primarily in the entrain-
ment separators just prior to emergence from the tower. The mist is probably
rather coarse, however, because high-power consuming devices such as jet
scrubbers do not exhibit substantially better performance than the low-
power-consuming spray towers.
-65-
-------
In an HF manufacturing plant, the packed tower is most frequently used for
emission control.
One important factor in packed tower design is the type and size of pack-
ing since it determines the efficiency, pressure drop, and flow rates at which
the flooding will occur. In the air pollution control application of the
packed tower, rather low concentration of gajes in the air stream are usually
encountered. Therefore, there is generally no need for a higher liquid flow
rate than that required for complete irrigation.
The quantities which are ordinarily fixed before a packed tower is de-
signed are:
1. Volumetric air flow rate, composition and temperature of
entering gas.
2. Composition and temperature of entering liquid (but not
flow rate).
3. Pressure.
4. Heat gain or loss.
Under these circumstances, it can be shown that the principal variables
still remaining are:
1. The liquid flaw rate (or liquid/gas ratio).
2. Height of packing (retention time).
3. The fractional absorption of any one component.
Any two of these last, but not all three, may be arbitrarily fixed by
a given design. The fractional absorption of HF, SiF^, and S02 depends on
the liquid used in the packed tower. Three types of liquid are used in the
-66-
-------
KF industry: acidic gypsum pond water, neutral plant water, and an alkaline
liquor containing lime or caustic. The efficiency of the equipment depends on
the choice of scrubbing liquid. There are no reliable data on fluoride removal
efficiency but it appears that acidic liquid would have an efficiency of 60 to
90%, neutral water about 90%, and caustic up to 99%. Consequently, a packed
tower with about 5 transfer units and an alkaline scrubbing liquid with a pH
of about 10-11 presents the best available control technology.
-------
7.3 Fugitive Emission Control
The major source of fugitive spar emission is usually the spar pile. Under
windy conditions, spar can become airborne and drift beyond the plant property
line especially when the pile is being worked. The best control for spar emis-
sion is to keep it in a storage building or silos. Less effective techniques
are to cover the pile with a tarp or use dust suppressing chemicals. Fugitive
emissions of spar in plant transport are best-controlled by baghouses. The
conveyor lines should be kept under negative pressure to prevent emission.
The reactor kiln is under 1/2 to 1 in. wg negative pressure under normal
operating conditions. Under upset conditions, the kiln can become a source
of concentrated HF emissions. Most plants practice one of twc control alter-
natives. The first is to have a standby scrubber connected to a kiln. The
scrubber is usually a packed bed with caustic as a scrubbing liquid. The gas
stream is separated from the scrubber by a rupture disc which is ruptured man-
ually in case of emergency. Some plants ha:ve a provision to short-circuit the
absorption train and go directly to the final scrubber in case of emergency.
The standby scrubber is a better concept and represents the best available
technology. Only 2 or 3 plants have no provision to control kiln fugitive
emissions. Most of the gypsum ponds used in HF manufacture are either
neutralized with lime or have an excess of lime resulting in a pond pH of
10-11. A few plants have acidic ponds with a pH of 1 which can be a source
of HF and SiFit emission. The best method for control of acidic ponds is liming.
Once the pH of pond water is brought to 5-7, no fluoride emissions are expected.
The second alternative is to use dry anhydrite treatment similar to the Buss
Process..
-68-
-------
Another source of HF fugitive emissions is tank car loading and unloading.
Figure 7-9 shows the emission control during tank car unloading. At least one
plant is known to have HF fugitive emission problems during tank car loading/
unloading.
7.4 Summary of Best Control Technology
There is no one single plant that uses the best control technology on all
emission sources. Some plants have better control on one source; some on another,
It appears that implementation of New Source Performance Standards would result
in equalizing control efforts throughout industry. Table 7-3 summarizes the
best available control technology for HF manufacturing plants. Since fluoride
is not a criteria pollutant NSPS would make it a designate pollutant and
regulation would apply to existing facilities. If the best control technology
were practiced in all plants the overall fluoride emissions would be reduced
by 20-30%.
-69-
-------
o
I
^TfO
Plf£
.1.3
A-2'
A I
^Hfj"-'
fci
GAUGE
h**4*;.f V:
l-l
TANK ; CAR
4 • 4.
toucnoN
PRESSURE REGUIATOR
AIR
IHIEJ
'Oi
*4*l>
for.
4Cf
^A/A
( 5
A.5
X
-ixi
3/«" P»PE t.4
-txj-
TO PROCESS
A- 7.
SAfEFir RUPTURE DISC
WITH
VACUUM PROTECTOR
^x
CHECK
VAIVE
^
-txh
GAUGF
G- 3
MH*J
V
-
(SEA1EO OPEN
I STEEt
=Lf
7«S
VENT
VAlVf
KEEP
C10SEO
V
GAt/GE
G-2
WATER SEPERATOR
\
r\TjZ^J
==^1—
TANK
ON SCA1E
X
2" PIPE-
EDUCTION
6" PIPE
VENF TO
GROUND
OR DITCH.
(I
TO
3""5 Hf ABSORP-
SURGE noN
TANK SySTEW
Figure 7-9: Typical Tank Car Unloading Connections When Using
Compressed Air for Unloading Anhydrous Hydrofluoric Acid7
-------
TABLE 7-3
BEST CONTROL TECHNOLOGY IN HF MANUFACTURE
Source
Pollutant
Control Equipment
Efficiency
7,
Spar dryer
Spar handling
and storage
Tail gas
Kiln upset
Gypsum pond
if acidic
HF loading/
unloading
HF dilution
Spar
particulate
Spar
fugitive
HF, SiF^, S02
HF, SiF^, S02
HF,
HF
HF
Fabric filter
Storage building or silo
plus fabric filter
Caustic scrubber
Caustic scrubber
Liming
MCA* Procedure
Caustic scrubber
99
99
99
90
99+
99+
99
*MCA - Manufacturing Chemists Association
-71-
-------
7.5 References
1. Billings, C.E., Fabric Filter Manual, The Mcllvaine Co., Northbrook, Illi-
nois, 1975.
2. Strauss, W., Industrial Gas Cleaning, p. 214, Pergamon Press, 1966
3. The Mcllvaine Scrubber Manual, The Mcllvaine Co., 1974.
4. Air Pollution Engineering Manual, Danielson, J.A., Ed., EPA, OAQPS, May
1973.
5. Boscak, V., Tendon, J., Odor Abatement: in Animal Food Manufacturing Plants,
Proceedings of the First Conference on Energy and Environment, College Cor-
ner, Ohio, 1973.
6. Lunde, K.E., Performance of Equipment for Control of Fluoride Emissions,
p. 293-293, Ind. Eng. Chem., Vol. 50, No. 3, March 1958.
7. Hydrofluoric Acid, Chemical Safety Data Sheet SD-25, Manufacturing Chemists
Association, Washington, DC, 1970 (Rev.).
-72-
-------
8.0 STATE AND LOCAL EMISSION REGULATIONS
The following sections discuss the state and local regulations
applicable to HF manufacturing and summarize these regulations. The
values in this section are given in the units that appear in the regulations.
8.1 Summary Of Applicable Emission Regulations
Although hydrofluoric acid manufacturing is regulated under the
permit: and particulate regulations of the states where operations exist,
no states have adopted regulations which specifically address HF production.
Rather, states treat HF manufacturing as a process industry for purposes
of air pollution control regulations. As such, eight types of control
requirements apply depending upon the particular jurisdiction:
1. General process weight limitations, typically using the following
equation:
E = 4.10 (P)0'67 where P < 30 tons/hr
E = [55.0 (P)0'11] - 40 where P >_ 30 tons/hr
Where
•
E represents allowable emission rate (Ib/hr) and P represents
process weight rate (tons/hr)
2. Hass particulate emissions limitations. These are generally
expressed in terms of allowable grains or pounds of particu-
late per standard cubic foot.
3,. Control efficiency limitations. The States of Ohio and New
Jersey use this approach.
4. Control based upon the stack gas flow rate. Texas uses this
type of regulation.
5. Visible emissions limitations. These are applicable in
virtually all states studied.
-73-
-------
6. Fugitive emissions limitations. These apply in most states
studied.
7. Ambient and emissions limitations for fluorides. These apply
in three of the states covered by this study: Kentucky,
Louisiana, and Texas.
8. "Catch-all" provisions. A number of states have such provi-
sions which are intended to control toxic or hazardous emis-
sions on a case-by-case basis.
The conclusion drawn from this analysis of State regulations is that
process weight and/or fluoride emissions standards apply to HF manufacturing
in virtually all states where operations exist. The level of enforcement of
these regulations is moderate and no State agency indicated that emissions
from this industry was a top agency priority.
8.2 List of Regulations Applicable to the Hydrofluoric Acid
Manufacturing Industry
Tables 8-1 through 8-9 present the State and local regulations on parti-
culate emissions, process weights, visible: emissions, fugitive emissions,
fluoride standards, and other related areas. Table 8-10 summaries the state
regulations on allowable fluoride emission.
-74-
-------
= • T — a — c.
i. • -- — a -as
• i^ J: . S 2
Tiaris j
1J > ^ > ^ 3
.. -r f ^ - r 1 - ? i- 5 = f "
r I
t ! =1= . - -?-5 'f j v- * ' r s.» :
^ = zt:| ; j:-^|j :jii:|l^£3^
-75-
-------
I'.MII.F. II t. Kent in fry Stale R"K I e lu Hi' H.iliill .11 till u
I'..I I I, III.I'l- I'l,,,:,•:,:! UeJ|;lil
Matter Finliii.lDii F.i|ii.il. Ion (S. e Fhiurlile St.in.ljnl«_ (Hlirr Appl 1,'ahl,
l.linll.H Ki'y lu. '.ixnlaiiat Ion) Vl"llile lull unions I'llf. Illvr l.li.l SH.'una Amlilelll |MH| -is lunu Id -i-.-i 1.11 IIII-M
In a.l.llllun In flu- Ken I IK-ky'il liiKll 'vi! '.(II KAK IMIJll Nol Appl leal. If Surll-m I ol Mil
I'-. ,nrja weight und emission legul.-il Inn (8)-l't liu.n y KAK l:0'ill piutlilos
ll,i p. ,,,iiw ill MM Kentucky A J - R
I a.: ( I 11 y ,il mt ul :,t rut I ve Kegn-
C.iiv.n, Illy, I..I ,',,,,:i. Seilli.n mas'l j'.li I I, u I a I.' 40J KA!t I: (l(,(l( I /i) , Slanilaiil fur l.n a r.in- liy-.
I,. Mliul.y la I. ti;,()(A) , i':.j.ali- eml Ms lunti llwllil- rrijulies (4ml .'iiu- UJNI.|>IIS Kin- eva liiat lull ol |>" •
:,,il, |,',l lu ||:-|,.:H Siaiulji.lii lion, .,| 401 KAK neniti-u) nil ii-u- orl,l,(a:i UK li.nl (ally II.I.-.H ,l»"';
I In- Si.ill- Air ill I'rl'l orhi.ini i! J :0(i()(/i) , vj.slhle uonable preeunt lonu rmf :*'i lon..j. 'lltlii
I'lillollrn Con lor proi U:IH iipt1- pal t Ic-.il M *• I'nilN- und pruil tl> 11 n t!.e I tine-av|>,. Stainlaril i I-^H lal tun IM ap-
liol i,,|iili, iall"iiu. Ilils Nlnna ate llmlli'.l illuLliarj-.u ol vltil- dlol lu ll.alilc to n.'V.iil
in. ill-, ol I lie li-giil.it ton allow. to 40? i.,:p»i'Uy. lite fugitive ,lu:il lie ex- ol the mure liiimliil
Kenlil'-ky Dlvl- owiti-rH tu tiMii|:ly eiul;lHfoil3 Leyuti.1 ceeilt'J i-iniss lon:i t rum
tilon ol Air wlili oltlier a pio' tlie prope.rty Hue. morrt tli.'in liyilroi hmrif arlil
ri-ss ui'l^hL llmllj- >iiire/yr^. plantH, Iiu; In.11 nr.
tlon o; ,-! ui.i.M!! pat- I lonnlll II.HI' ai III mhil.
I leulate eml UM Ion 1 week ) . tiA
llmllal Inn of II.t)2
|-raln:i |iel Stan- ""'i hour ?.f,H
ilaul i-illilt fii.,1 at Jt-ll'J!" J'-1!?
il Hi I il llmim ol -J/£
a, liial i.'iuov.il 'id I KAK I:()!'()('0-
elflrienry I'l Imai y ?-l an.l.u ,l:i
fur Total Hii.ii I.I.'K
(nu IInoi die Iron)
(n) Hot tu i Ki'eeil
I'UtHiKS.s IIKICHT HJIIATKINS ^o l>[m (u/u)-.i«e-
raj'e runeent I at Ion
Key: ,>( muni lily u.tmples
,. ,, over d' owing lieasiill
(AI K 4.10 (P> ' (Kefiintlens of F Vain,.) (not |o esi-eed f. i-un
n ff bi'i'iillvi- months).
(B) K - '..III (1-) •"' (P .: K/|,r) (I,) Ni:t In exeee.1
K * !'••>.0 (I1) ' I 40.0 (f- J U) lon:i/ln) aveiai-.e.
(. ) Mul lu exrei',1
80 ppm (w/v) I nionlli
K ' Allowalile eiiilHulou iaie In pouu<|s per
houi , an.l
F " Ci.iei-un we I Kh| rail: hi Ions per l.oiil
-------
IAi'1,1 U 1, l.uululuua bt«tr Ht i;ul,M I " Ml h'.iml'.ieturlnp
I'arH unlal i- l'rurc>-4ii U:'.'|'Ju.
M:il In (.ml b-ilnn F.i|nat lun (Her Flniirlile Jit.inJ.ii I)H mliei An|>llial>le
ri.inls l.lnllh Key lor (•.*)> l< ni.lt Ion) Visible Km 1 ..H lima PnKlllvt- Ki.il NM l,,ii:i Aiulilrnl 1 ml :.s limn KI-I;II lat Ions
Hie Allied Section It.1) ol II Se.lli.ii l'l.r,.l i-ilab- Section IV.) l|ii'i:l- Alllioue.h l.onlu- Although then: Under Sell lout.
I i.-l I li I,:-, a| ib,' :.,MI| „..,•!,i li lt:'.| a gr.tir.il VD': Cica ibal nil nil- I ana .1,','H not are no speilll- 'i. '1.1 and 14 H.I,
li.ilim t(ii,i)',e All I'ollllllon opacity Mt indnril uon.iblc ]M cram Ions have an aii.hlerl le i Inol Ide tlie I.ml i li lan.i All
and llel-.Nll 1(111111)1 Kiy.iil.l- wlileh may he e-treed- mil HI lie taken In f him Ide lil ail emission slan- O.iality Seellen
and lit.- K il- tl, i, \t i»;t ai>l I slu'M ltd lur not wore- tlian pifvent par) lenlalefl dard. Section ilards upjilli-n- b.i:i rbe autliorliy
>ei |i I nit at a Ki-nerj} pn>ei.'s.4 4 Minutes In "ny 1:^11- i rum bi'diNlhc nir- H.2 ut l\\v i'e|*~ Me to UK manii- In establish p.u ~
r.iameiiy ale weight erufnlutil. i.n'lillvv 60 mlnillnd. liutiie. Sevun uui li ill.itliMin |)lu- laetlirliiK In tli-ntale emls:;li>n
all giiveini-d llii'lei Section precaul luliu nil: lilhll:l eiuhi- In l.olll s l.ili.l, HI ,1ndal UM fm pi>-
by I he l.iMilii- I'J.H, ||ie SI,ill! i;|>ei_ 1 f I td, lluliullng fll-jim wliluli HIT t Ions 11.2, lenrlally loxle
I .in.i Stale All may tighten I lie line ul •! lul will . .Mi.il- "nil- 9.2-1, Kml tl, pollutants ubleli
I'olliillon llnvie I lull Is lor i;ol IcctorH. dc-ilrilile lev- 111 prohibit are «,.,re Hlrln-
lli'iilrol tuHli iiaillcu- i'l»" (I.e., i-mlH-ilnnn i;i'"l Ilini wnnld
Ke^n lal IOIIH. late I:IH|M[|OII:|. tiaimfnl to Itn- whli'li wuclil olhi'iulse .ipplv.
wans, an I ma I H runse "tinjc-
plwnlH or |>ro|i- ulrablf lev-
i.'riy) ol any el*j" uf any
air jM.'i Ivii.nii . pi>! iiiiaiit .
ThlM lias direct Tin Lunlnl-
appt I eat lini Ln aim Air Cun-
fluorldeti and Ll i>l CiHHinlK^
arid ml MI s sloii lias
emitted by aduilnl stra-
l'HtlCl,SS WKIiaiT KQIIATfliHS liyrti of linn li- tlvrly lui-
II. Id plants. pi em, I, ted
K'>: Ilil., a,i-
0 67 "llir "V I'X
(A) li - 4.10 (!•) ' (Rcgardlpso ot p Valnu) et.i al.l IN!,-
0 hJ Inf. ;1 24-hr
(B) I: • 4.10 (I') ' (I- < lun.i/lir) P.|.ilvalr.it
/i li ambient
K - I Vj.lt II') ' I - 40.0 (I1 J JO lonM/lir) flnorlile
Htan.laril of
W1"'lo! 1/20 T.I..V.
..I the prop-
l< - Allowable emlualon rale In po(ir.ds |:,--r eitv line.
limn , and
I' •- Troeess uol^lit rale In Ions j>cr hour
-------
I,,1,1,1 ,-i .'.. nl,|,, Si ilf Ki-Kiilal Inn A|i|il Ii-Ml. 11- It" Ill M.iimf11 tin 11.1
oo
I'l.i.il :i
II,,. lln ,,!,., w
l,i. II II y III
Cl.vil.li,,! l-t
Hill. ,fi:l In
M. -HI- Hit"
wel 1 ;IH lii -
• .1 1 rt-'-lll .1 -
1 Inns ..I III.'
Ill 1 II -III. Ill-
till If I Klllls-.lnll
1 Illlltli
KiKiil.il li»i l/.Vi-
1 /-1 1 I.I lilt Illtltl
.Ml ! .il Inl li.n t nil-
1 ml iii-Kiil, n |, in...
limits till ImliiH-
t In- iii.iri- si r 1 n^f nl
nf lu.i l.v.-l-i: (I)
.1 pi III1. SU Wf 1 I'.llt
t'l.nU'H.-i UVIj;lu
i:.|n u inn is,',- i- lu, ii LIP :
K. Y Ini l.npl.in.it Inn) VlHlLli Kiul :IH I.IIIH Kn^lllv. 1 ml us l.i.i.l Ai.iMrnI
U Si. Hv Ki|!ul Jt I.. ii 1745- Suit.- Ri'ijiil. il I..II Not .ippl If.ililu
17-07 vi.t, •!>! Hlim a lien- J745-17 OS n--
or.nl t'l'~ ,.| i, liy limit tpilies an.l i-iiiimu-
(t;,.. 1 II h,ti, 1, m.inn) Inr rales lla- "tr.ititmn-
ti 1 1 sttiirei's. A i~mlnutR-b)r pri-i. .iiit IOIIH"
Inwinri- ul up ti> AtlZ Vt-nt p.ii l icu l;ii »-
(Nti. 1 Rlnxli'mliill) Id M.lttrr flora lif-
lirnvl.lftl I'ur . fitmlnp, ,il rli.n in- .
. ._
ilunil.ii.lu Olhf i Appl
1 n.lii., l.-n-i H, i-iil.il 1
Nnl nppl 1, ,i|.|f HIM 1 Km
117 nl U
l;,-,.,,il.n l
K.-I.I i-.il
Will ill pi
pnt 1 nt If
WntllJ III
ll.lllll pvil
III v/f 1 1 i
,irc prt'si'iii i
III Illltt I till
l.lly of Cl.-v- limit (uff n. /.t
I (n.I. Iliu ...I u) in (2)
u |n-i c( IIL i'f f i t IIMI
cy i«>|M->tiiiitfii in hi?,.
H-l. | Iguru H-l (i l.iu-s
lint uutrol U (I H.ISM K.itti
u( r.nlMsl.m (.itisrlssa)
In m.ixIfHiidi a tlnw-il'] <•
tnasM r.itf «>I t-inlriajoii
(..i ,1 [.Hi.-) . 'I he piii-
fi-;is Urli'J.t 1 In.ll r.'
iif lit It i.'I 1.1 Is i lt( 1 n
f Ir prm CHS fli it m.iy
r.ni'K' any ciui ss i«>r. tit
(in ( U n I.it <• in it tc-r
I (i m ts j mi nit a I low tb 1 «•
in »:. i r.it f i»t -x-i,,l ss 1-iti.
l!tt | i". •••(., w*-!/l.t t iml |
>.h.i t i ji|'|< I y f ti ii"ti
at t ,i lint'iil ill o.i f; Inr I'll1
wln-ir (I,, M.H.on* t.>| | •.!
tl.i .-, K.ilr i>( IjalKslon
.•.iinu.l hr ;i..i r, lal.,..l
I (H I oi rh.ll ,t» I rr t /,,il I on
lor the (ft IK i;:;s is ini-
t> n»un. Citi vi- I' I nl
.il Inns I H .1
.il |>rUH .t
t Ion uliJch
nut f.i.'ion ilil
iv.il.l 1.- In-all
II ,ii,' or i on
tile a I'tilil Ir
nil I n.imc .
SS WK.IOIIT h:<)UATIi>NS
(A) i: = 4.10 (l')°'6/ (Ki-Barillpsii .if P V.iltiu)
(II) L - It. 10 (I1)"'6' (T < tuiki/hr)
K - IS3.0 (l')0'"l - 4)1.0 (I- -1 10 i DIM /hi)
I* ~' A) Itiw.lli I L- i-niluslnn l;ir.- Ill |.mititl-i |ii-i
lnxii , .mil
I1 - I'i.iiTSK wrl'',lil lillo In t.tlis pL'l lintii
-------
< ' ' "x tn -- |
-79-
-------
o
on
UJ
10-'
on
on
<
5 10*
u.
S o
I 100
CURVE P-l
CURVE P-2
CURVE P-3
(I)-COLLECTOR EFFICIENCY REQUIRED (S)*
100
103
10s
U-UNCONTROLED MASS RATE OF EMISSION Ib/hr
NOTE: AFTER JULY 1, 1975, CURVE P-l APPLIES IN ALL CASES
WHERE THIS REQUIREMENT IS DEEMED APPLICABLE.
Figure 8-1: Ohio Collector Efficiency Curve1*
10s
-80-
-------
-3
- e
^
*± —
«!* I Ut'.'i - ^3 *: j 22 4 251^
Sllll^lil ipHl =-| - = ±i
-^11iilr = ?= I^^ M * S?^ fill
* , s:r -
'4 ;
= "t
-81-
-------
TAKI.K. H-fi. I'L-iul-.yl v.iul.l I CMIIIIIIMIV-', :ll I li KrKii I n t liHIN Appl J r.ilili. lo UK Mainlfai'1 111 Inf.
I'l.illl M
Me 1 ( (in I ho
A:. hi Hid 1,1, :l
Illy .11 (.1, li
dun li,tr t hr
Allliil i> 1 l li.ihli-
| to :;UL|I opi>-
OO iai Inns are
^ In. In.l.'d lor
till Hi IH.IL lOIKli
purposHH.
l';irt lrnl.it t.' 1'rort'as Weight
M.iLlL'i I'JulHaloti Kijnatli'ii (.'lu,'
l.lmltii K,-y loi r,«| 1. in. ll lull)
!)frlloii 123, 11 of Not At>ii 1 1 r.tli 1 1>
Lit.' IV'msy I v.'inld
Al r hi'Hunr* cni
Id'i;, il.it Icnu rt^u-
in'illur eml si. loiu.
1 roii. p» oct'as opc-
r.il Inn a. Tor pru-
rir>:.'i upor.it IOIIM not
hpi1* II 1. al ly 1 IsLcd
(UK H.innl art urine
1 s .111 unl l:il rd
pr.i.tviri) allow-
able; tml.'i:ilons
arc grHfililcally
(Hunt rated In
FIHini' H-2.
Vlall>U< EmlaNluna
S.'rt Ion J **A 41 i>ro~
hlhllii vtsilile
i-'ulsalmin. 1 In- o|i.i-
r lly nl which:
I) cr|uj|lt; or ex-
Lei^!] 20! fur an
aggregate or Mure
than 1 minute* In
any one lu>nr, or
2) equal « ur ex-
ci'i-.lu 6l)t at any
lime.
Thin ll»lt.lt lull
ilocR not iipi'ly
to fugitive mls-
Klonn which arc1
(MTHlttoJ tllldur
hLTtlOII 12J.I
(MUU twxt column).
Kii|;ll Ivu Min|.,itloiiH
Si'i'Llon 1 / J I ( ti ) ( 9 )
prolilhllii f,i(;lllv..
.•UI|K.S|IMIH unlt'HH the
I'cniisylv.inla DI.K di'-
alonu ar.r ul minor
«I«nll 'Ir.incc and
nro not provfnt Ing
the- at 1,-tliMK'nl or
m.ilnl oii.in, r of .my
ami, lent stnnJnrd.
Sor. 121. !(.:) s|irrl-
flou err 1.1 In t i'/i:iiiii-
• ililc |>ri'Caut Ions In
pi evrnt f ny 1 1 ivft
tm I -is ions -lii-i:. 1 2 I, 2
jirohlblts riij>
part Iculat o emlHtiloiiH
al the |,io|..'i ty I In.!
ulilrh nro IIN
tin. I'l'iniKyl- I2/.72, o|iri.i not :i lorlh ,i
v.inla KL-T.ula- ilni; I'.'i'mll )},'iier>il |i..r-
I luns rsl.ili- appl lint lona iillilllon .i)ialii!;l
IUHII riuot l.li! i|ii.-st flhow
hl.lndard of th.il 1 llf
*> |ii;/M3 (lo- uoiirrt1 will
lal si.lnhlr n, i| vlul.iti'
uti UK) . Any iimMi'iit
air fpi.il Ity
R| and. ml.
-------
C.C4
0.03
c
o",
m
:? 0.02
100,000
1 I 1
200,000 300,000 400,000
E = EFFLUENT GAS VOLUME, dry scfm
THIS GRAPH TRANSLATES AS FOLLOWS:
(i) 0.04 GRAINS PER DRY STANDARD CUBIC FOOT,
WHEN THE EFFLUENT GAS VOLUME IS LESS THAN
150,000 DRY STANDARD CUBIC FEET PER MINUTE.
(ii) THE RATE DETERMINED 3Y THE FORMULA:
A = 6COOE-1, WHERE:
A = ALLOWABLE EMISSIONS IN GRAINS PER DRY
STANDARD CUBIC- FOOT, AND
E = EFFLUENT GAS VOLUME IN DRY STANDARD PER
CUBIC FEET PER MINUTE,
WHEN E IS EQUAL TO OR GREATER THAN 150,000
BUT LESS THAN 300,000.
(iii) 0.02 GRAINS PER DRY STANDARD CUBIC
FOOT, WHEN THE EFFLUENT GAS VOLUME IS
GREATER THAN 300,000 DRY STANDARD CUSIC
FEET PER MINUTE.
Figure 8-2: Pennsylvania Allowable Emissions Curve
for Sources Not Listed in Section 123.136
-------
IA I'I !•. rt /. •|i>r..iti Slillt- k.-KM!.II I.ins A|.|.l I, ilil,- l.i IIF ll.ulnf .ir t nt in|>
I'.ill li -iilad* I'luri-iu Mi>l|;hl
ll.illi-i Mn, fusion l-i*. ,.M Ion (Si-i1 _ Flnorlih> 4jlan;l I !«'' t'wl uu Ions Amlilfitl I'ml MM lon.q KIT," Inl IOIIM
Tin' Me 113, K»l« 105 nf Texas Hut. ,\|'|i> I ral>U Kuli- 101 of Toxin Ki't'i- Hiiltf lO/i of I.'/ rj !>uu Kli;n[it Sn: I l|>uii< Hole S I :i .1 ,;cn
li'i|"'nl ..n. I Hi |;i"l.it Ion | I'Ml.lli- l.ll loll") 1 nrnlillilltl ex- Kl'glllal Inn I UN- K ">. fl - 1 . rl.ll nil I I:;IIIIT
:'i|.inf I i r I I.', IK'S |i,-irt liiil.llr ir:i:il"« vliilMe cinln- I ul. I I i.luiin from .IHV cncloseil mrr.Ht^ "vra::cn:i|il<' hit- in .ill |>oll
I'-lnl I,.H.,|.r.'< .ml IUIIK" wl. I rli lion.
l.i I'd i I r .nut .louiLt'H oil, .-i Ullli rofi|io, I tu stack mist lie ailo|»t c.l to
(jrouiiM Hiiyoti (li.ui tlio^c piiir- i:i»l MHloiis, i IIP rule pin-vent pan Irn-
r»;»l>ci:l 1 vi-l y UHiilug iir li^inil- t;p^cifiiii u 10£ p|>d^ Intcn from lid'omlnfr
ait- all null- 1 1 iiy a;',r ten 1 1 in - rliy jlrolt» -ivci jiged alrliomu In aroau
In i u. CI.H.V n| ciununilli II-H. over a 5-mlnuio pel I oil, wlilrli «ic nonal-
Sl.ii,. All I'ol Stac-ks i un.'il riu li d af- talimiMil tor i lie
1'itlon Con- SonrriM snl,|i-ii I IT .l.inuiiiy 31, 1972, jmhlcnt (inrt 1 1 iil.il .'
liol lii';;ol.i- to Uol. 100 mil: l nru limited lo ?f)2 m.iild.iril.
lions. I'orloim lo I In- o|i.irtty on .1 "i-mlnntc
u I lowiili !<• cmlx- avfki:igo.
' i. Ion i al rH a:i
_|^ hllOWII III KI|',IIIH
i H-! ai!.!/oi tl{-
uri- 8-'i. K.-ir.li
ri'j;n l.u rM i-ini*;-
HlniiM ari-orillng
to the c-l I liienl
flow I. He ol UK-
for Hl.i, t hflglit.
In .nl, II t Jon, Hull-
ID'S L'Sl.lllllsllCN
an amli I'.-ii I all
>|ii.-il llv r«'la| ul
fm I sf: I on ;ii. aii«|;irJ
vlid h prill, !l>l ts
part lfiil.it i* <-i,il M-
alon whl<'li won!,!
rausi* anv of I hi'
t Imt'-nveia^i'd net
y,i omul Irvr i |>ar -
I i filial >• ronn-n-
I i. it l"ir. lo l>r
-------
- -A = = =
-85-
-------
Effluent Flow Rate
acfm
1,000
2,000
4,000
6,000
8,000
10,000
20,000
40,000
60,000
80,000
100,000
200,000
400,000
600,000
800,000
1,000,000
Sate of Emission
Ib/hr
3.5
5-3
8.2
10.6
12.6
14.5
22.3
34.2
44.0
52.6
60.4
92.9
143.0
184.0
219.4
252.0
Interpolation and extrapolation of the data in this table shall be
accomplished by the use of the equation E * 0.048 q^*°2 where E is
the allowable emission rate in Ib/hr and q is the stack effluent
flow rate in acfm.
Figure 8-3: Texas Allowable Particulate Emission
Rates for Specific Flow Rates7
-86-
-------
c
I/I
ca
*^»
o
10°
105
STACK EFFLUENT FLOW RATE (acfm)
"igure S-4: Texas Allowable Participate Emission
Rates for Specific Flow Rates
-87-
-------
co
CO
The Board declarea that concentration* of gaseou* Inorganic fluoride
cuoi|>oiinda In tha atmoaphara, calculated aa UF, In excess of I
.5 ppb for eny 12-hour parlod
.5 ppb for any 24-hour period
.0 p|>b for any 7-day parlod
•0 ppb for any }0-day period
by vo urn* at 760 m llg and 2) degree* C average conetltute undealr-
sbla evela, whether th* aourcea ara froai natural causes or froai tha
actlvltlea of man. and that a atate of air pollution exlste when con-
centrations of any gaseous Inorganic fluoride compound, calculated aa
IIF, exceed any of than* levela.
b. The Board further declaroa that concentrations of Inorganic fluoride
compounds In forage located In a Type D land uae area. Including In-
organic fluoride compound* both absorbed In snd deposited on forage,
calculated aa fluoride Ion, In axcaa* of any of the following levela
Indicate the presence of undesirable levels In the area In uhlch th*
forage I* grown, whether th* aourcea ara froai natural cause* or frost
the activities of man; and that • state of air pollution exist* when
concentrat lone of Inorganic fluorid* confound*, calculated •* fluorid*
Ion, exceed any of th* specified levels!
(I) An everage of 40 parts per Billion by weight baaed on staple*
taken once a month over • period of 12 consecutive cslendsr
nonthsj or
(2) An sversg* of 60 part* per Billion by weight based on aimplea
taken once a month over • period of three conaacutlve calendar
monthii or
(J) Ar. average sf 30 parts par at it Ion by weight baaed on **mp»ea
taken one* a month over • period of two consecutive calendar
month*.
To assist In meeting th* ambient air quality standard*, th* loard
hereby establishes • Halt on th* million of gaseous inorganic fluoride
coapotinda, calculated a* IIF. which may b* made from any property not to
exceed 6 pert* per billion by volume average during a parlod of ) consecu-
tive hours. The contribution of Inorganic fluorid* coeipound* by •
•ingle property aha11 be measured by th* difference betwaan th* upwind
level and the downwind level of Inorganic fluoride compounda for the
property, or by atack aampllng calculated to a downwind concentration.
The Milmum allowable fluoride emission rate which may be mad* turn
• stack on a property to comply with the cmlaaion Halt sat forth In this
Regulation My be calculated by Button's Equation which ha* bean modified
to consider th* critical wind apeed and 'to correspond to a J-liour air
lampl*. Th* aquations used for fluorid* for cold and hot atack* are!
1. For exit stack gaa for temparaturea of lea* than 121 degree* F.
(•) All land us* types
1
q» • 5.8 x 10"*V d *
1.29
Wharst
Qa - emission rat* lb*/hr.
V - atack exit velocity, ft/sec.
d - exit *t*ck dlanater, ft.
h( - phyalcal atack height, ft.
(See Graph 1.)
2, tor exit stsck gee for temperatures greater than 125 degree* F.
<•) All lend type*
ti i
1.5 t 0.82 (=M
\ •/ • "t
wherei
Qa - eataalon rat*, Ibt/hr.
V • atack exit velocity, ft/aee.
d" - exit atack dlaaater, ft.
•>, • physical atack halt lit. ft.
AT • teuparatura difference between atack gas and tlia wit-
door temperature* of 90*P. (550*a) la aasimod in pra-
parlng dlaperalon graph*.
T • atack axlt temperature In 'Rankina.
(Sea Graph 2.)
Figure a-5:
Texas Fluoride Standards
(Key Excerpts from Regulation III)7
-------
C
o
10C
.. 10-1
o
10-2
EXIT STACK GAS VELOCITY IN ft/sec
5 10 20 30 40 60 80 100
IO"1 10° 1C1
STACK EMISSION RATE IN Ib/hr
HYDROGEN FLUORIDE
FOR USE WHEN' THE EXIT TEMPERATURE IS LESS THAN 125°F
TO PLOT GRAPH 1, ASSUME A BASIC STACK HEIGHT OF 100 FEET
AND PLOTS 4f_ 1.23 FGR VARIOUS STACK DIAMETERS VERSUS STACK
VELOCITY. '°°
Figure 8-5: (continued) Graph 1
-------
c
c£
_
t—
C/l
1C3
10-
STACK EXIT INSIDE DIAMETER IN FEET
2 3 4 5 6 7
3 9 10 11 12
10-1
10°
10*
STACK EMISSION RATE IN Ib/hr
HYDROGEN 'FLUORIDE
FOR USE WHEN THE EXIT TEMPERATURE IS GREATER THAN 1253?
TO PLOT GRAPH 2, ASSUME A BASIC STACK HEIGHT OF ICO
FIET AND AN EXIT VELOCITY OF 20 ft/sac. LET STACK GAS
Figure 8-5: (continued) Graph 2
-90-
-------
!.'!!!!• II-R. W;-.;l Vlr!-;lnl.-| Sliili Rc|r'll.H lfi,:l Appi trulilr to I!*' M.lllHf Hi Mir ll.R
I'iiri I.nl.Hi- l'io,i'3H Wi-lj;l\l .... t i
M.mi., riiMHKlon K,t,,.ill,.,, (So,, ... . M,M,rUsl..n« Awl.l.-.H Kmlssln.m R,.e.,l.,t I
II,,. A,,,,.., K,T.,,l.,tlon III N.,1 ,Vpll, ,l.lr S«,:«l..» 2 of «,-,;„- Si- I U-n 4 of RoRi.M- II,, t A,,p 11 mhlo N,,t An,l 1. a|, I,. S.,. I I „,, 1. 11 ..I
, ..-llliv.il ,.r the W,.s, VI, Lillon VII i-ruhlLHn tloi, VII r.-.|,,1ro» Ko,;» .,11..,, VII
NM , W V, tth.l.. Air l',.ll,,. fi-oK' o.lsHlon, „• Inslal l.t Im, U,,,l rcR,,lat..« ,.,.l,:,u •
I I,,,',,.,', ' I l.m «,.,.,„ ., , »<-u3« ,,r No. I „« „*,. ..f f,,,,ltlvt. |,«r- . « >y I oxlr , ,.ls-
,,,,|y ,„.,,.-„, r..,v,.-,,,; (..ircK,,- Kli,t;lm.,ni. Cli.,,1. | I, ,.l;Hif n.nl i »1 Syn- Hlona.
,1, .,(,||M||,,n I.Hu i-mlsulonn An nl Inu-iiff Inr ti-u.-j lopfll.rr will,
, i ,, ,....., I row »,jn,ifa, l.ir- i,|. 10 «... 2 ij sulf.iMc m.vl p-ivltig
!„;' |,rii.--.'in: -.pc - provlileJ n>r pc- a»«l R«>,«l i'|>»'V-il liifi
ii,ti<>n:i. iir at Id rlod.n .iKKri-K-itl'ig prai I leu Dl.iiid.inl.M
i.:iu,il.-i.-LiirliiK Is '"> •«'••«.• H"»« 5 K> ...nlrul
,1 type "vi" ciMire,. mlnntiM in any I- iliinl.
,ii>.lf'i It.-KHl'ill'.n I" • period.
VII ittttl w.xi Itl
lln-.virc li .-illy Im
61,1, | ell to I III'
ptl.rv'NS wt'l^lil
| I linll.1l I"lis il|'|>l I-
^O f.'thl*' I,i fi,,,-l,
M M.tir,-.-::. !!"Wi-"!>r.
MllliM-ll lit: III Cllllf!~
Hlini urc it,,! f»v-
cn.l by tlic SI.II.-'H
pr.i«'i:'>'. wrl^l.)
rr|;ul;il Itni. hi.rlliri-
,ttt,l't', thf. Ht'ftll.l. >>lt
Mll,.M'i>l ;l.:l if,
'.. I ) .11.d 'i of :
-------
iii :
3 r
c" 5
| 1 x j-s] f
— c ; •_• s w i
?c.?-i1'".
— X j ,. —
~ " • j 5 •••
-92-
-------
TABLE 8-10
SUMMARY OF STATE REGULATION ON ALLOWABLE FLUORIDE EMISSIONS
STATE
California
(Bay Area)
Kentucky
Louisiana
New Jersey
Ohio
Pennsylvania
Texas
Ves t
1 Virginia
COMPANY
Allied
Penwalt
Allied/
Kaiser
Lssex
Harshaw
Allied
Alcoa/
Dupont/
• Stauffer
Allied
1
LOCATION
Pittsburg
Calvert City
Baton Rouge/
Geismar /Cramer cy
Paulsboro
Cleveland
i
Marcus Hook
Point Comfort/
La Porte/
Green Bayou
I
! Nitro
ALLOWABLE EMISSION RATE
4.10 (P)°-67
4.1CKE)?:67 P < 30 tons/hr
155 (P) -40 P 1 30 tons/hr
Same as Above
.At: w«oi*
*n» *»ion A.' w*ol«
• t« t-e man
p4*«fit:al '.b« o«r -v . ; »aurc* <(*• a;«
>of« saurca »V titi- score* 3j ft »n
-pwauan .11 tic;- if (Scacdvd •:». 0 0 CJin*
,1tn.F*thr.i ;»l •cnom :: . ptram.) ?- ;CD
50 or !«*• 0 5 J-'XJO cr !•>• J i
100 1.0 i.OCO I J
I'joo o.o is.:oo i J
:ooo 0.3 ro.ooo : o
2000 ;r 4r«*t«r 0.0 1*0 OCO 4 J
.7! ."00 ir
-------
8.3 Definition of Plant Modification
The Clean Air Act defines a "modification" as
" ...... any physical change in, or change in the method
of operation of, a stationary source which increases
the amount of any air pollutant emitted by such source
or which results in the emission of any air pollutant
not previously emitted. (§100 (a) (4)).
EPA NSPS regulations (40 CFR 60) implement the modification concept by
narrowing its applicability to specific facilities within an entire source. As
such, the regulations define a modification as any physical or operational
change to an existing "-facility which results in an increase in the emission rate
of any pollutant covered by a new source performance standard.
Typical examples of a modification within an HF plant would be:
1. Use of different packing in the scrubber.
2. Change in liquid to gas ratio in the scrubber.
3. Higher J^SQ^ to spar ratio.
The determination of whether a physical or operational change will
increase the emission rate is based, wherever possible, on AP-42 emission
factors. However, where AP-42 factors do not yield a clear-cut answer,
material balances, continuous monitoring data or manual emission tests must
be employed. In cases where emission rate changes are difficult to determine
or where industry-specific guidance is necessary the Administrator has
the authority to promulgate industry-specific definitions of what constitutes
a modification for any particular facility in that industry. Regardless of
the definition or method employed, however, compliance with all applicable
performance standards must be achieved within 180 days after completion of
the modification.
-94-
-------
Under EPA regulations, a modification was not deemed to occur if the
source owner was able to offset an emissfon rate increase by reducing emissions
elsewhere within the plant. This bubble concept allows a plant operator who
altered an existing facility in a way that Increased its emissions to avoid
application of the standards by decreasing emissions from other facilities
within the plant. This concept was rejected in the recent case of ASARCO, INC.
v. EPA 11 ERC 1129 (D.C C.R., 1978) and EPA is currently in the process of
removing this provision from the regulations.
It should be pointed out that the modification section of the NSPS regulations
specifically exempt several types of activities including:
1. Routine maintenance, repair or replacement;
2,. An increase in production rate accomplished without a capital
expenditure;
3., An increase in the hours of operation;
4. Use of an alternative fuel or raw material if, prior to the date
any standard under the part becomes applicable to that source type,
as provided by §60.1, the existing facility was designed to accom-
modate that alternative use;
5. The addition or use of any system or device whose primary function
is the reduction of air pollutants, except when an emission control
system is removed or is replaced by a system which the Administrator
determines to be less environmentally beneficial;
6. The relocation or change in ownership of an existing facility.
-95-
-------
1.4 References *
1. Copy of applicable regulations sent from the Bay Area Air Pollution
Control District in San Francisco, California.
2., Environment Reporter - State Air Laws, pp. 386:0501 et. seq.
3., Environment Reporter - State Air Laws, pp. 391:0501 et. seq.
4. Environment Reporter - State Air Laws, pp. 476:0501 - 476:0541
5. Copy of applicable regulations sent from the City of Cleveland
6. Environment Reporter - State Air Laws, pp. 491:0541 - 491:0741
7. Environment Reporter - State Air Laws, pp. 521:0521 - 521:0581
8. Environment Reporter - State Air Laws, pp. 546:0501 et. seq.
9. Environment Reporter - State Air Laws, pp. 451:0501 et. seq.
NOTE - All literature references were verified through the applicable state
and local air pollution control agencies.
-96-
-------
9.0 HF MANUFACTURE EMISSION SOURCE SAMPLING AND ANALYSIS
There are three major groups of pollutants that can be encountered in
Hr manufacture.
1. Particulates, primarily CaF2-
2. Fluorides, primarily HF and Sir,.
3. Combustion related pollutants: SO , NO , and CO.
X X
Table 9-1 presents a list of identified pollutants in HF manufacture
and summarizes sampling and analysis techniques.
Determination of the emission rates is basically the same for all of the
potentially emitted pollutants. It is necessary to measure the concentration
of the pollutant by analyzing a sample which is representative of that in the
duct or stack and which is characteristic of normal process operating condi-
tions. It is also necessary to measure the volumetric flow rate of the gases
in the duct or stack at the time of sampling. The substance mass emission rate
is then calculated from the measured concentration and volumetric flow rate.
The following sections contain concise descriptions of the recommended
sampling and analysis methods for the emissions from the HF manufacturing
process. Not all methods have documented precision and accuracy and this
information is provided only as available in the literature or determined
bv the. contractor.
-97-
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TABLE 9-1 SAMPLING AND ANALYSIS TECHNIQUES FOR THE EMISSIONS FOR HF
POLLUTANT
SAMPLING TECHNIQUE
ANALYSIS TECHNIQUE
Particulate,
CaF;>,
fugitive
Si02>
impurities
Isokinetic with
collection on glass
fiber filters. Methods
5 or 17.
Gravimetric Method
5 or 17.
Total Fluorides,
HF, SiF.
Isokinetic with membrane
filter and impingers with
distilled water
Method 13.
Simplified Train
Remote sensing
SPADNS - Zirconium
Lake or specific
ion electrode.
SPADNS - Zirconium
Lake or specific
ion electrode.
Infrared absorption
and Emission Spectroscopy.
Sulfur dioxide
S00
Sampled at constant rate
through midget bubbler
containing isopropanol and
midget impingers containing
hydrogen peroxide.
Method o.
Barium-thorin
filtration
Carbon Monoxide
CO
Integrated bag or
continuous
NDIR (Non-dispersive
infra-red)
Nitrogen oxides
NO
x
Grab sample collected into
evacuated flask containing
a dilute sulfuric acid-
hydrogen peroxide absorbing
solution
Method 7.
Colorimeteric using
phenoldisulfonic acid
(PDS) procedure.
-98-
-------
9.1 Particulates
Particulate emission rates can be measured using the sampling and analy-
sis techniques specified by Method 5 - Determination of Particulate Emissions -
from Stationary Sources or Method 17 - Determination of Particulate Emissions
2
from Stationary Sources (Instack Filtration Method). Sampling and analysis
procedures in both methods are essentially the same, the only difference
being the location of the filter. Method 5 has a filter located outside the
stack and thus the sample stream temperature must be maintained above the con-
densation point. Diagrams of the sampling trains for Methods 5 and 17 are
presented in Figures 9-1 and 9-2, respectively.
9,2 Total Fluorides
The fluorides emission from HF manufacture expected to be in gaseous
fora consist of HF and SiF/ .
'The emission rates of total fluorides can be measured using the samp-
ling and analysis techniques specified in either Method 13 - Determination of
Total Fluoride Emissions from Stationary Sources - SPADNS Zirconium Lake
Method or Method 13 B - Determination of Total Fluoride Emissions from Sta-
tionary Sources - Specific Ion Electrode Method? The sample collection sys-
tem and technique are similar to those of Method 5 for particulate.
Upon completion of sampling, the filter, impinger catch, probe wash and
impinger wash are placed in a sample container. The weight of total fluorides
collected is determined either by the SPADNS Zirconium Lake colorimetric method
or by a specific ion electrode. To obtain the emission rate, the weight of the
total fluorides is divided by the sample volume corrected to standard condi-
tions and multiplied by the volumetric flow rate in the duct corrected to stan-
dard conditions.
-99-
-------
L
TEMPERATURE SENSOR
^- I'ROUE
O~
PI TO i Hint
I'HOUE-
T
IMPINGEU TRAIN OPTIONAL, HAY BE REPLACED
liY AN EQUIVAUNT CUNDENSOK
THERMOMETER v
STACK WAIL
\ rl:ILTER IIOLUER
HEATED AREA
,1?
n 1
REVERSE TYPE-
PI TOT THHE
3
I'llOI MANOMETER
THERMOMETERS
OKU ICE
r^_,£ u
MAIN VALVE \
Y-.I
VACUUM 1.1 III
IVACUUM GAUUE
DRY TEST METER Alfl-TKUlf PUMP
Figure 9-1: Mctlunl 5 particul ale-snmp] ] nj1, train
-------
=3
•o
-101-
-------
Analysis by the SPADNS Zirconium Lake colorimetrie method of twenty repli-
cate stack emission samples with a concentration range of 39 to 360 mg/1 resulted
in a relative standard deviation of 3 per cent. A phosphate rock standard with
a certified value of 3.84 per cent fluoride was measured to have an average value
of 3.88 percent fluoride based on 5 determinations. The accuracy of fluoride
electrode measured has been reported to be in the range of 1 to 5 per cent in
the concentration range of 0.04 to 80 mg/1. The collection efficiency of
Method 13 sampling train is presented in reference 4.
-------
9.2.1 TRC's Experience with Fluoride Sampling and Analysis
At the end of August. 1977, TRC and EPA carried out the field program
at CF Industries plant near Bartow, Florida. The purpose of the program was to
validate the ROSE (Remote Optical Sensing of Emission) for the measurement of
fluoride emission from the gypsum pond and to estimate the fluoride emission
rate.
During the field program wet sampling/analysis was employed to determine
fluoride emission at various points around the gypsum pound. The schematic of
the sampling station is shown in Figure 9-3.
The results obtained during the field program were somewhat inconclusive
and some questions were raised about the applicability of the simplified sampling train.
Consequently, the calibration of the sampling train and fluoride analysis was
carried out in controlled lab conditions to determine methods, precision and
accuracy.
The ROSE method is based on absorpotion of hydrogen fluoride (HF) in 0.1N
aqueous solution of sodium hydroxide and subsequent spectrophotometric
determination of dissolved fluoride (using the SPADNS method). The experimental
arrangement is shown in Figure 9-4.
The experimental arrangement incorporated a dynamic dilution system in
which a stream of known concentration of HF was mixed with a stream of air
taken from outside the building. Mixing occurred in a 7.5 ft. long section
of a polyvinyl chloride duct 6 inches in dia.meter. Air velocity in the duct
was 2,000 ft/Qi.n. The gases were absorbed with five impinger trains operated
simultaneously. Each impinger train consisted of two impingers in series
followed by a flow meter and a gas volume meter.
The influence of the following parameters on accuracy and precision
were studied:
-103-
-------
VALVE
EiPIKCERS
DRY GAS METER
_J
PUMP
ROTAMETER
CENERATG?.
•7ESTICAL TRAVERSE SAMPLING' STATION
GENERATOR
Figure 9-3: Schematic of a Ground Upwind-Downwind and Vertical
Traverse Sar.pling Station
-104-
-------
I
I-1
o
I
400 ACfH
All) FINK I
ours MIL OF
ri I
7.5 ft.
I Pilot tube I
K201)0 ft/mln)l
I It IIP In II2 I
comprcsscJ gisl
Iconipresseii »ir|
10 GUIS IDE
THE nUILOIIIG
Fif.tirt; 9-4: Experimental Arrangement Cor Kvnl un L Ion of
llydroj;iMi nuurlik: Sampling and Analysis
-------
-sampling time (1 hr. to 2.5 hrs.)
-concentration of HF (50 ppb, 20 ppb)
-effect of inpinger type (Greenberg Smith, standard tip)
-effect of tubing used in train assembly (Tygon, polypropylene)
-length of tubing used in train assembly (Tygon, polypropylene)
-presence of ice around the impingers
-liquid volume in the impingers (100, 80, 60, 40 ml in the
first impinger, 100 ml in the second impinger)
-gas sampling rate through the train (21, 26, 36, 47 1/min)
The maximum number of identical tests was four, corresponding to four
sampling trains operating simultaneously under the same conditions. The basic
precision and accuracy of the method were determined in this way. Standard
deviation was calculated for each group of four tests. The error for each
group was expressed as a difference between the HF concentration as analyzed
and the HF concentration as prepared. HF concentration as prepared was
considered the true concentration.
Standard deviation of the results for groups of four simultaneous
experiments ranged from 14% to 27%, with 18% as the average value. The
error ranged from 1% to 35%, with an average value of 18%, and was
positive for all the groups of experiments.
Different sampling conditions were often used for each of the four
simultaneously operating sampling trains. This provided a faster way for
evaluation of the effect of individual sampling variables on method accuracy
and precision. A variable was considered to have no effect when the
difference between the concentration of HF as analyzed and as prepared were
within the experimental error.
Within experimental error, none of the variables investigated in this
study was found to have an effect on the accuracy and precision of the
method.
-106-
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Over 90% (mcst frequently close to 100%) of the total HF absorbed in
trains was absorbed in the first impinger whenever the initial liquid volume
in the first impinger was above 40 mis. The only exception was noted when
the sampling rate through the inipingers was reduced to 21 1/min. Then
81% HF was absorbed in the first impinger. These preliminary results thus
indicate that a reduction in sampling rate may reduce absorption efficiency
probably due to less intense turbulence.
The conclusion of this study is that a simplified sampling train can be
used lor relatively simple and reasonably reliable determination of fluorides,
It is recommended for field work when high accuracy is not required and the
emission stream contains only gaseous fluorides.
-107-
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9.2.2 Remote Sensing of Fluoride Emissions
During recent years, EPA's Environmentcil Sciences Research Laboratory
at Research Triangle Park (ESRL/RTP) has been developing remote sensing tech-
niques for gaseous pollutants. In the course of the measurement of fluoride
emissions for a gypsum pond, described in Section 9.2.1, the ROSE System was
used for identification of the fluoride species evolving from the pond. The
major advantages of the ROSE System over wet sampling/analysis are5:
a. It gives a long path (up to 1 km) average concentra-
tion. This makes it a perfect tool for fugitive
emission measurement.
b. It provides practically real time measurement requir-
ing no sample handling.
c. It can distinguish between HF and SiF^.
ROSE is a high-resolution IR spectrometer system. It utilizes a Fourier-
transform interferometer to cover the 1.7-15 micron spectral region. This
system has been installed in a van and can be used in the long-path absorption
mode with a remote light source, or in a single-ended mode to observe emission
signals from gases at elevated temperatures. All components necessary to ob-
tain plotted spectra in the field are contained in a van.6
The main parts of the ROSE System are shown in Figure 9-5.
For absorption measurements over paths up to several kilometers, a Dall-
Kirkham f/5 telescope with a 30 cm diameter primary mirror is used to colli-
mate energy from a light source. Originally, a 1500°K blackbody was used as
the source. Presently, a 1000 watt quartz-iodine lamp, which provides sig-
nificantly more energy in the near IR and nearly as much energy in the middle
IR as compared with the blackbody, is used. Generally, the light source and
telescope system is installed in a small truck and driven to a desired loca-
tion; a small generator powers the light source.
The remainder of the ROSE System has been installed in a 28-foot van. A
telescope identical to that described above collects energy from the remote light
-108-
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VAN WALL
REMOTE LIGHT
SOURCE. (/5,30cm
LIGHT
SOURCE
-V,'-
INTERFEROMETER
I
FPA ROSE Infrared Specrromocnr System
-------
source through a port in the side of the van. To measure the signal from warm
gases exiting a smoke stack, an elliptically shaped flat mirror (mounted on
a platform attached to the van) reflects energy through the port into the
telescope. The telescope focuses energy at the aperture of the interferometer.
The interferometer and peripheral equipment is a standard Nicolet Instrument
Corporation Model 7199 RT-IR System configured to fit into the van. Major
components consist of a computer with 40K memory, dual-density disc with
4.8 million, 20-bit word capacity, teletype, paper tape reader, oscilloscope
interactive display unit, and a high-speed digital plotter.
The interferometer itself is mounted on the telescope support structure.
All other systems (except the plotter) are arranged in two 19-inch relay racks.
Two beamsplitters, KBr and CaF2> are currently available for use in the
interferometer. A dual element, sandwich type detector is mounted in a
liquid nitrogen dewar. For the 6000 to 1200 cm"1 region InSb is used and
HgCdTe is used from 1800 to 600 cm"1, with the two regions scanned separately.
Power for the ROSE system, including heating or air conditioning, is
supplied by a 10 kw generator. During operation of the system, the generator
is lowered from the van to the ground using an electrically-operated winch.
This procedure is necessary to avoid electrical and mechanical interference
with the operation of the interferometer. The entire system, including
remote light source, can be placed in operation at a field site in about one
hour under normal conditions. Auxiliary equipment carried in the van
includes a weather station for recording wind velocity and temperature and a
laser range-finder for measuring path lengths.
The first field use of the ROSE interferometer system was at a phosphate
fertilizer plant gypsum pond. A series of these ponds are used at fertilizer-
plants for wastewater treatment. The ponds, which are generally rectangular
-110-
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in shape with boundary dimensions as long as a kilometer, are particularly suitable
for long-path measurements. The particular environmental problem presented by
these ponds is that they give off gaseous fluorides. In past studies using wet
chemistry sampling methods, it had been possible to measure only total fluorides.
Analysis of the pond chemistry indicates that expected gaseous fluorides would
be SiF^ and/or HF. Thus a study was undertaken at the C. F. Industries
fertilizer plant near Bartow, Florida, to determine specifically which gaseous
fluorides are emitted from the ponds.
A series of measurements were made at various locations around several
ponds with path lengths ranging from 500 to 1000 meters. Typical spectra
obtained are shown in Figure 9-6. The upper spectrum was taken over a 900 meter
path at: a location known to be free of HF. The middle spectrum was taken
over an 860 meter path across a gypsum pond. Both spectra were taken with a
resolution of 0.125 cm"1 (molecules cm"2)"1 and a half-width of 0.04 cm"1; the
HF concentration was determined using the equivalent-width method. The
calculations were carried out with an existing computer program. For the
HF line1, shown, the path-averaged concentration was determined to be 45 ppb.
(It was not possible to calibrate the HF spectrum with the sample cell
method since our gas handling system is not resistant to HF.) Absorption
due to the SiF^ fundamental band centered at 1031.5 cm"1 could not be
detected. Calibration spectra indicated that 0.5 ppb of SiF, would have
produced about 4 percent absorption over an 860 meter path, and this value
is taken as a reasonable lever sensitivity limit.
Contact with regulatory agencies and HF manufacture plants revealed no
data on fluoride emissions from gypsum ponds. Although gypsum ponds used
in HF manufacture probably generate less fluorides than phosphate fertilizer
manufacture, measurement should _be carried out to determine the environmental
impact. Use of the ROSE System and simplified sampling train is recommended
for the measurement program.
-Ill-
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.EP.Q_.ROSE_SYSJEM.
o
Q
UJO
Co..
RTMOSPHERIC PRTH 900 METERS
RESOLUTION =0.125 CM -1
LTJ
en
4168..- 4170 - 4172 4174 4176
• • '. • • "I- '= WflVENUMBERS -
4178
:_ GYPSUM POND .
- RESOLUTION =
860 METERS
0.125 CM -1
4168 _ 4170 4172 4174 4176 4178
._______: WRVENUMBERS_
SUBTRflCTED SPECTRUM
«fci73.5 417^.7 4173.9 4171*.! 417*4.3 417li.~5
WBVENUMBERS
Figure 9-6: Gypsum Pond Spectra
-112-
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10.0 ENVIRONMENTAL EFFECTS OF FLUORIDE EMISSIONS
Fluorine is considered a welfare-related rather than a health-related
pollutant because it has no significant effect on human health in the concentrations
found in the atmosphere even under the most adverse conditions. However, atmospheric
concentrations which can exist around processes emitting fluorine compounds can
adversely affect plants and animals, which may pose an indirect threat to our
economy and general welfare.
In nature, fluorine is widely distributed in minerals such as fluorspar
and fluoropatite, the prime constituent of phosphate rock. Atmospheric
fluorine contaminants are emitted primarily from heavy chemical industries
which utilize fluorine compounds as catalysts or fluxes. The major sources
of these pollutants are phosphate fertilizer, aluminum and steel plants, and
manufacturers of fluorinated plastics and fluorinated hydrocarbons. The
effects of fluorides on vegetation have been known since the late 1800's, but
it was not until the rapid industrial expansion of the 1940's that its effects
were recognized as significant.1
10.1 Vegetation Effects
The severity of injury sustained by vegetation exposed to fluoride con-
taminants is dependent primarily on the form taken by the pollutant. Fluoride
is taken up by absorption into the plant tissues, usually through the leaves,
where it flows toward the margins and accumulates. This gradual accumulation,
combined with the length of exposure and total fluoride concentration in the
ambient atmosphere, determines the degree of injury. Gaseous compounds are
probably responsible for most plant damage since they are easily absorbed. Most
research to date has dealt mainly with exposure to gaseous fluorides such as
hydrogen fluoride, fluorine, silicon tetrafTuoride or fluorosilicic acid.
Fluoride in oarticulace form is hazardous only when it is soluble and therefore
able to be absorbed into the plant tissues.1
-113-
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Susceptibility
Although all plants naturally contain varying amounts of fluorine, certain
species are more susceptible to its effects than others. There are many factors
involved in a plant's reaction to fluorides, often making it difficult to
determine the exact cause of injury. Certain environmental factors such as
rainfall, temperature and winds may result in Injuries which are almost
impossible to distinguish from pollution damage.3 Table 10-1 is an example
of the pollutant concentrations affecting both sensitive and resistant varieties
of some economically important crops.
TABLE 1Q-12
HYDROGEN FLUORIDE CONCENTRATIONS
AND EXPOSURES FOR SENSITIVE AND
RESISTANT PLANT SPECIES
Plant
Corn
Tomato
Alfalfa
Sorghum
Sensitive Varieties
Concentration
2 ppb
10 ppb
100 ppb
.7 ppb
Exposure
10 days
100 days
120 days
15 days
Resistant Varieties
Concentration
800 ppb
700 ppb
700 ppb
15 ppb
Exposure
A Hrs
6 days
10 days
3 days
Most forage crops are fairly tolerant as are several species of vegetables and
deciduous trees. Some species sensitive to fluoride are certain conifers,
fruits, berries and grasses. These sensitive varieties generally exhibit damage
at concentrations between 0.5 ppb and 1.2 ppb for several consecutive days.1* In
comparison, 5-10 ppm of fluoride are normally accumulated by plants in the
absence of an atmospheric fluoride source.^
-114-
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Injuries
Probably the most apparent effect of fluoride on vegetation is necrosis
or tip-burn. This injury is characterized by discoloration around the edges
of the leaves caused by the accumulation of fluoride in these areas. This
is the most economically significant impact of fluoride contamination.
Although necrosis does not necessarily har-n the vegetation, the concentra-
tions may be too high to be safely ingested by animals.1* In addition, if
the marketed portion of a plant is visibly damaged, it could result in great
economic loss, even chough actual injury to the plant may be slight.
Exposure of vegetation of fluorides may also result in abnormalities or
a decrease in reproductivity. Studies have shown abnormalities in growth
including reduced leaf size, longer needles in Douglas Fir, and decreased tree
growth. Host effects which limit or reduce growth are accompanied by visible
injury; however, if the exposure to the fluoride source occurs late in the
growing season, there may be little or no effect on the vegetation.^
10.2 Effect on Farm Animals^
Atmospheric fluorides pose an indirect hazard to farm animals in their con-
tamination of forage crops by absorption and accumulation in the vegetative tissues,
Generally, the effects of fluoride contamination are felt only on farms situated
near a fluoride-emitting facility or industries with inferior emission control
systems. Since the inhalation of industrial emissions contributes very little
to the total intake of atmospheric fluorides, soluble fluorides are more harmful
to farm animals than the dust from phosphate rock or limestone.**
The fluorine ingested by animals is deposited almost entirely in the bones.
While adult animals normally have concentrations of about 500 ppm in their bones,
it takes concentrations of 5000 ppm before' visible signs of the pollutant's
effects are apparent.3
-115-
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The studies performed on farm animals to date have revealed a sequence in
which the effects of fluoride contamination appear. These are:
Dental lesions, primarily in the incisors
Hyperostosis, or bone overgrowth
Lameness
Loss of appetite
Decrease in milk production
Reduced reproduction
The last two effects are believed to occur from the decreased food intake caused
by the loss of appetite. In one study performed, cattle were fed forage con-
taining 600-1200 ppm of fluoride, resulting in a 50% decrease in food consumption
due to their loss of appetite. Economically, this is the most serious effect
of fluoride contamination in farm animals.^
A continuous intake of 40-50 ppm of fluoride eventually results in the
destruction of incisors, meaning inhibited grazing and great economic loss.
However, this damage occurs slowly; thus the economic impact would not reach
its maximum until exposure had continued for about five years. Dental injury
would also not be more likely to occur in young animals, and would not be
expected in adults.14 Table 10-2 lists the fluorine which can be ingested
safely by livestock.
TABLE 10-2a
SAFE LEVEL OF FLUORINE IN LIVESTOCK FEED
Source
Animal
Dairy Cattle
Beef Cattle
Sheep
Swine
Chicken
Turkey
Soluble Fluoride
(ppm)
30-50
40-50
70-100
70-100
150-300
300-400
Rock Phosphate
(ppm)
60-100
65-100
100-200
100-200
300-400
-
-116-
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Fortunately, animals having high fluoride concentrations in their bones do
not have contaminated meat or milk. Their loss of appetite will affect
their production, but the pollutant is not passed on. Nursing calves do not
suffer from fluorosis (abnormal calcification of the teeth) until they begin
grazing contaminated forage.2
10.3 Effects in Man
Regardless of the source of the fluoride its effects are essentially
the same; hyperostosis and fluorosis. Generally these conditions occur only in
growing children.3
The current threshold limit value for hydrogen fluoride is 3 ppm, while
the limit for particulate fluoride is 2.5 mg/m3. Owing to these occupational
limits, persons seldom are exposed to such concentrations, and very few cases
of adverse effects from atmospheric fluoride occur, even in proximity to
industrial sources. The maximum daily concentration inhaled near fertilizer
facilities is about 150 ug which is insignificant when compared to concentra-
tions of 1200 yg received from food and water.2
In man, the airborne fluorides are absorbed through the skin and from the
respiratory tract and are accumulated in bones and teeth. The more soluble
fluorine compounds are absorbed from the gastrointestinal tract into the blood
' much more readily than less soluble compounds. These are the forms that will
accumulate in the bone structures.2 Studies have revealed that the body is able
to absorb 87% of calcium fluoride from cryolite, 62% of sodium fluoride, and
37% of calcium fluoride derived from bonemeal. About half of the absorbed
fluoride is excreted, with the remainder being accumulated in the bones.3
Since research done to date indicates that airborne fluorides not not
present a direct threat to man except from uncontrolled occupational exposures.
-117-
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Their significant impact to man lies in the potential for economic loss by
contamination of plants and animals.
10.A Other Effects
Fluoride is capable of etching glass at concentrations of 590 ppb for a
period of 9 hours and pronounced etching occurs at concentrations of 790 ppl
for 14.5 hours. However, severe damage seldom or never occurs due to the
emission regulations imposed on industry.1*
Fluorides also have a damaging effect on the high silica brick lining of
furnace walls used in aluminum processing.1*
Hydrogen fluoride is especially significant in the reactions between
fluorides and silicon compounds which result in damage to ceramics and glass.
However, it is very difficult to isolate the effects of fluorides from other
background pollutants.
10.5 References
1. Jacobson, Jay, Hill, A. Clyde, 1970. Recognition of Air Pollution
Injury to Vegetation: A Pictorial Atlas, Informative Report No. 1
APCA,, Pittsburgh, PA, pp D-l - D-6.
2. Office of Air Quality Planning and Standards, 1976. Final Guideline
Document: Control of Fluoride Emissions from Existing Phosphate
Fertilizer Plants. Office of Air and Waste Management, U.S. Environmental
Protection Agency, pp. 2-1 - 2-10.
3. Stern, Arthur C., 1977. Air Pollution Volume II, New York, p. 169.
4. Robinson, J.M. et al. Engineering and Cost Effectiveness Study of
Fluoride Emissions Control Volume I. TRW Systems Group, McLean, VA,
1972, pp. 5-1 - 5-11.
-118-
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11.0 EMISSION REDUCTION WITH NEW SOURCE PERFORMANCE STANDARDS
11.1 Introduction
Model IV is a methodology developed by EPA's Emissions Standards and
Engineering Division which quantitatively estimates the anticipated impact of new
or revised standards of performance in reducing atmospheric emissions. Model IV
mathematically relates emission producing activities, such as industrial growth,
and offsetting emission control activities such as existing regulations, NSPS,
and the Clean Air Act. The resulting net emissions are projected for target
years.
Using Model IV, the differential in atmospheric emissions that could be
expected with and without NSPS can be expressed and the potential for additional
controls evaluated. For example, a maximum emission differential or NSPS impact
would be observed for an industry for which a stringent standard of performance
was technically feasible, but for which there were no existing state emission
limitations. On the other hand, a minimum or zero emission differential NSPS or
impact would be observed for an industry if a standard of performance repre-
senting best control technology was generally equal to existing state regula-
tions. NPS would have few beneficial effects in the latter case in reducing
emissions.
TRC in a 1976 EPA report1 developed Model IV data and results for approxi-
mately 190 industrial categories, including hydrofluoric acid.
Utilizing the best available 1978 data, TRC has updated the Model IV
input variables to calculate the estimated impact of instituting New Source
Performance Standards based on best available control technology.
-119-
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!1.2 Model IV - Background Information
The impact of new or revised standard of performance is expressed in Model IV
(T - T)
Where: T * emissions under baseline year control regulations.
T = emissions under new or revised standards of performance.
Factors such as increased production capacity, construction to replace
obsolete capacity, control technology, and present allowable emissions are
used to develop the above relationship. Table 11-1 defines these parameters
used in the Model IV equations. From the input variables, T and !„ the
total emissions in the ith year under baseline year regulations and revised
standards of performance, respectively, are calculated, where:
T = E K (A-B) + E K (B+C) (11-1)
S S S
(A-B) + EL.K (B+C) (11-2)
= K (B+C) (Eg - F^) (11-3)
Other related equations are:
1) Assumption of compound growth B = A [(1+PA) """-I] (11-4)
C = A [(1+P ) X-l] (11-5)
2) Assumption of simple growth B = Ai P (11-6)
C - Ai P (11-7)
c
Where i = elapsed time in years.
-120-
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3) baseline year emissions T « E KA (11-8)
A S
4) Uncontrolled emissions T = E K (A-B) + E K (B+C) (11-9)
5) For pollutants regulated under Sec. lll(d) of the Clean Air Act.
TNP" Elll(d)K (A-B)
Where £..,,,.= allowable emissions as required by Section lll(d)
G_ = total emissions in ith year under Section lll(d)
For these calculations the baseline year is defined as- 1977 and the
ith year, 1987.
-121-
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TABLE 11-1.
MODEL IV INPUT VARIABLES
T = total emission in i year under baseline year regulations
(tons/yr)
th
T = total emission in i " year under new or revised NSPS which
th
have been promulgated in the j year (tons/yr)
T = total emissions in i year assuming no control (tons/yr)
T = total emissions in baseline year under baseline year regula-
tions (tons/yr)
K= normal fractional utilization rate of existing capacity,
assumed constant during time interval
A= baseline year production capacity (production units/yr)
B= production capacity from construction and modification to
replacement obsolete facilities (production units/yr)
C= production capacity from construction and modification to
increase output above baseline year capacity (production
units/yr)
? = construction and modification rate to replace obsolete capacity
(decimal fraction of baseline capacity/yr)
P = construction and modification rate to increase industry capacity
u
(decimal fraction of baseline capacity/yr)
E = allowable emissions under existing regulations (mass/unit capacity)
-122-
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E« allowable emissions under standards of performance (mass/unit capacity)
E» emissions with no control (mass/unit capacity)
For the purpose of this study, the i year is defined as 1987 and the
jth year, 1977.
-123-
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11 . 3 Industrial Factors
K. Factor
K is the normal fractional utilization rate of existing capacity. The
fluorocarbon ban and aluminum inventory surplus have affected the product!* n
of hydrofluoric acid and chis significant decrease is reflected in K Factor.
In the baseline year, 1977, production of hydrofluoric acid was 74% of
capacity, based on production and capacity da<_a for the HF industry. In
the following five year span, plants project a small or zero increase in
production. In addition, major HF production facilities in Louisiana
and Texas will be ceasing operations, and in 1982 utilization of 70% of
the industry capacity is projected. The estimated K Factor for the entire
1977-1987 period is 73%.
? Factor
?„ the construction rate to increase industry capacity, is expected
^ >
to be zero during the ten year period 1977-1987. The 1977 baseline capacity
of 369 thousands tons of hydrofluoric acid is not expected to be exceeded
?B Faccor
As with P ? the. construction and modification rate to replace
L; a,
obsolete capacity is projected to be zero during 1977-1987.
A Factor
The A Factor is the 1977 baseline year capacity. As previously
stated, the 1977 capacity for the hydrofluoric acid industry is 369
thousands tons of anhydrous HF.
-124-
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Assuming 99% particulate removal efficiency,
E = 3500 Ib./ton 100% HF
For allowable emissions, the average process weight rate is calculated
as:
96__tpn_acid x 3500 Ib. fluorspar x . 34,000/lb./
ton acid 24 hr' fluorspar hr.
Allowable particulate emissions are determined for each state based
on the above process weight rate and weighted according to the fractional
capacity occurrence for 1977. Allowable emissions were calculated to be
19.5 Ib./hr. It should be noted that West Virginia has no particulate
regulations for the HF industry based on an inconsistency in the state air
pollution law.
E is calculated for 19.5 Ib./hr. and 96 tons of acid per day to be
4.9 Ib./ton acid. However, 35 Ib./ton HF is the best control technologically
feasible. Therefore, E = F~^ as control regulations can only be set as
S ^i
low as current technology will permit.
-125-
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Exit gas streams from the HF process are scrubbed with jets and sprays
to remove SC>2 and fluoride emissions. The estimated removal efficiency for
sulfur dioxide by the scrubber is 96% - 99%. Therefore,
E^ - 0.1 Ib./ton 100% HF
The allowable sulfur dixoide emissions from process systems vary from
state to state. West Virgina, Louisiana, Ohio and New Jersey limit sulfur
dioxide process emissions to 2000 ppm. Other states do not have any appli-
cable regulations. Assuming an average kiln emission flow rate of 5000 scfo
and an average capacity of 96 tons of acid/day for each of the eleven (11)
existing HF plants, the allowable sulfur dioxide emissions can be calculated
for the regulated states. For Louisiana, New Jersey, West Virginia, and Ohio,
E equals 25 Ib./ton 100% KF.
These limits for E are greater than E Therefore, for all states
s u.
the allowable S02 emissions are equal to uncontrolled S02 process emissions
and E = E
s u.
Particulate Emissions
Particulates are released during the drying of fluorspar. Literature
values are not available specifically on particulate emissions for uncontrolled
sources in hydrofluoric acid manufacture. However, use of a baghouse can
achieve 99% particulate removal. In addition, particulate emissions for a
well-controlled plant have been estimated at 20 Ib./ton fluorspar.2 Using
3500 Ib. fluorspar/ton 100% HF, best available controlled emissions with
a baghouse are:
E = 35 Ib./ton 100% HF
-125-
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11.A Emission Factors
Acid Production
Hydrofluoric acid is produced by the reaction of fluorspar with sulfuric
acid in a rotary kiln. One ton of anhydrous HF requires 3500 Ib. fluorspar
'28C' Car-', and 6400 Ib. I^SO^. While the grade of HF acid produced varies,
952 anhydrous and 5% 70% grade acid is typical of plant production.
Fluoride Emissions
Uncontrolled fluoride emissions from a rotary kiln have been estimated
at 50 Ib./ton of acid.2
Therefore, E = 50 Ib./ton acid.
The best available control technology for control of fluoride emissions
is use of a wet scrubber j with a removal efficiency over 99%. E for the
controlled emissions of fluorides is estimated at .2 Ib./ton acid.
As there are no regulations for fluoride emissions (other than ambient air
limitations), the allowable emissions of luorides, E , is equal to the uncon-
trolled emissions. Therefore,
E = E =50 Ib/ton acid.
s u
Sulfur Oxide Emissions
While the sulfuric acid in the hydrofluoric acid reaction produces a
calcium sulfate slurry, sulfur in acid grade fluorspar creates sulfur
dioxide emissions.
Fluorspar is approximately 0.03% sulfur content, assuming 3500 Ib.
fluorspar produces one ton of anhydrons HF, 1.05 Ib. S or 2.1 Ib. S02
are emitted per ton of 100% hydrofluoric acid. Therefore,
E = 2.1 Ib./ton 100% HF
-127-
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11.5 Results of Model IV Calculations
Table 11-2 summarizes the Model IV industrial and emission factors
for the hydrofluoric acid industry.
TABLE 11-2
MODEL IV INDUSTRIAL AND EMISSION FACTORS - HYDROFLUORIC ACID
Pollutant
Fluorides
Sulfur oxides
Particulates
emission factors
E
u
*N
E
s
Ib/ton 100% HF
50
2.1
3500
0.2
0.1
35
50
2.1
35
K
73%
73%
73%
growth rates
PB
/yr
0
0
0
pc
/yr
0
0
0
industry capacity j
A
B
ton/vr 100% HF
369xl03
36 9x10 3
369xl03
0
0
0
c
0
0
0
Utilizing the input parameters outlined in Table 11-2, the 1987 impact
of new source performance standards, T - T , was calculated to be zero
for the hydrofluoric acid industry. This is due to the projected lack of
increase in production capacity, a result of the fluorocarbon ban and aluminum
inventory surplus.
In addition, a review of emissions control on an industry-wide basis
indicates that most plants are currently utilizing best control technology
(e.g. - baghouse and scrubbers). There is not enough data on HF and
fugitive emissions to draw a clear conclusion on plant emissions, but it
appears that little pollution reduction would be achieved by retrofitting
existing plants.
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11.6 References
1. Impact of New Source Performance Standards on 1985 National Emissions
from Stationary Sources, TRC - The Research Corporation of New England
Report to EPA - 450/3-017.
2. Compilation of Air Pollutant Emission Factors (2nd Ed.) EPA Publication
No. AP-42, April 1973.
-------
12.0 LIST OF CONTACTS
Plants
ALLIED CHEMICAL
Corporate
Mr. M. C.. Mosher
Supervisor
Environmental Administration
Industrial Chemicals Division
Allied Chemical
P 0 Box 1139 R
Morristown, N J 07960
Telephone:(201)455-3888
Mr. W. M. Reiter, ?.E.
Director,, Pollution Control
Corporate Environmental Services
Allied Chemical
? 0 Box 1057 R
Morristown, N J 07960
Telephone:(201)455-6159
Baton Rouge, LA
Mr. M. Lapari - Environmental Supervisor
Mr. D. Templet - Production Manager
Specialty Chemicals Division
Allied Chemical
P 0 Box 2830
Baton Rouge, LA 70821
Telephone:
Mr. Anthony J. Stewart
Division Patent Council
Industrial Chemicals Division
Allied Chemicals
Law Department
Corporate Headquarters
P 0 Box 1057 R
Morristown, N J 07960
Telephone:(201)455-4033
Geisaar, LA
Mr. W. J. Dessert, Superintendent
Process & Environmental
Engineering
Agricultural Division
Mr. H.L. Arnold, Plant Manager
Allied Chemical
Geismar Complex
P 0 Box 226
Geismer, LA 70734
Telephone:(504)642-8311
Pittsburg, CA
Mr. F. G. Nicar, Plant Manager
Industrial Chemicals Division
Allied Chemicals
Nichols Read
Pittsburg, CA 94565
Telephone:(415)453-3292
Nitro, T«. V.
Contact through M. C. Mosher
Corporate Office
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DUPOHT
Corporate
Mr. R. H. Morgan
Environmental Affairs-N-6537
Petrochemical Department
E. I. DuPont De Nemours & Co.,
1007 Market Street
Wilmington, DE 19898
Telephone:(302)774-7662
Inc.
ALCOA
Corporate
Mr. P. R. Atkins
Manager-Environmental Control
Aluminum Company of America
1501 Alcoa Building
Pittsburgh, PA 15219
Telephone:(412)553-3805
La Porte, TX
Mr. R. H. Johnson
Environmental Coordinator
Biochemicals Department
E. I. DuPont de Nemours & Co.,
Houston Plant
P 0 Box 347
La Porte, TX 77571
Telephone:(713)471-2771
Inc.
Point Comfort, TX
Mr. J. C. Mayfield
Mr. A. A. Rambikur
Operations Environmental Control
Superintendent
Aluminum Company of America
State Highway 35
Point Comfort, TX 77978
Telephone:(512)987-2631
Mr. A.R. Ceperley
Area Supervisor-Technical
Mr. C. L. Tice
Engineer-Technical
Biochemical Department
E. I. DuPont de Nemours & Co.,
Houston Plant
P 0 Box 347
La Porte, TX 77571
Telephone:(713)471-2771
Inc.
EAaSHAW
Mr. S. J. Gunsel
Manager, Pollution Control
Mr. Joseph Berish
Director of Environmental Control
The Harshaw Chemical Company
1945 E. 97th Street
Cleveland, OH 44106
Telephone:(216)721-8300
-131-
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ESSEX
Corporate
Mr. R. Wagner
Vies President of Operations
Essex Chemical Corporation.
1401 Broad Street
Clifton, N J
Telephone:(201)773-6306
STAUFFER
Corporate
Mr. E. C. Conant
T. Savers
Stauffer Chemical Company
Westport, CT 06880
Telephone:(203)222-3000
Paulsboro, K J
Mr. James Ferguson
Plant Supervisor
Essex Chemical Corporation
100 Thomas Lane
Paulsboro, N J
Telephone:(609)423-2050
Greens Bayou, TX
Mr. G. W. Fry
Plane Manager
Industrial Chemical Division
Stauffer Chemical Company.
1632 Haden Road
Houston, TX 77015
Telephone:(713)453-7175
KAISER
Mr. R. W. Curtis
Chief Environmental Engineer
Kaiser Aluminum & Chemical Corporation
P 0 Box 337
Gramercy, LA 70052
Telephone:(502)395-7121
PE3NWALT
Mr. C. ?. Dalrymple
Supervisor, Environmental Affairs
Pennwalt Corporation
Calvert City, KY 42029
Telephone:(502)395-7121
-132-
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STATE & LOCAL REGULATORY AGENCIES
TEXAS
Mr. T. Palaer
Corpus Christy Office
Texas Air Control Board
1305 Shoreline Blvd. #124
Corpus Christi, TX
Tel:(512-3332961
Mr. W. N. Allen
Texas Air Control Board
8520 Shoal Creek Blvd
Austin, TX 78758
Tel:(512)451-5711
Mr. G. Speller
N. P. Peer
Texas Air Control Board
Air Quality Control Region 7
5555 West Loop, Suite 300
Bellaire, TX 77401
Tel:(512)451-5711
LOUISIANA
Mr. G. Vonbodungen
Louisiana Air Pollution Control Conmissio:
Baton Rouge, LA
Tel:(504) 563-5120
CALIFORNIA
Mr. W. deBoisblanc
Bay Area Air Pollution Control District
939 Ellis Street
San Francisco, CA 94109
Tel:(415)771-6000
NEW JERSEY
Mr. A. F. DiGenni
State of New Jersey
Department of Environmental Protection
100 Larvin Road
Cherry Hill, N J 08034
Tel:(609)795-7390
-133-
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STATE & LOCAL REGULATORY AGENCIES (con't)
OHIO
Mr. Lian Ang
Ohio EPA
Division of Air Pollution Control
2735 Broadway Avenue
Cleveland, OH
Tel:(216)664-3508
WEST VIRGINIA
Mr. D. Stone
lie. R. Weiser
West Virginia Air Pollution
Control Commission
1558 Washington Street, East
Charleston, W V 25311
Tel:(304)348-3286
KENTUCKY
Mr. S. M. Murphy
J. T. Smither
Commonwealth of Kentucky
Department of Natural Resources &
Environmental Protection
Frankfort, KY 40601
Tel:(502)504-3382
-134-
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing/
REPORT NO.
EPA 450/3-73-109
3. RECIPIENT'S ACCESSION NO.
TIT.E AND SUBTITLE
Screening Study on Feasibility of Standards .
Performance for Hydrofluoric Acid Manufacture
of
5. REPORT DATE
October, 1978 Date of Issue
6. PERFORMING ORGANIZATION CODE
7. AUTHCR(S)
Vladimir iJoscak
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
The Research Corporation of New England
125 Silas Deane Highway
Wethersfield, CT 06109
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-02-2615/Task 6
12. SPONSORING AGENCY NAME AND ADDRESS
DAA for Air Quality Planning and Standards
Office of Air, Noise, and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA 200/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report contains background information on the hydrofluoric acid manu-
facturing industry such as the number of plants, their size, and location. This
information was obtained in the open technical literature and through visits to
several typical plants.
The economic profile of the industry indicates there will be no growth in
the next five years.
General description of the manufacturing process, emission sources, emission
rates, and controls are the main part of the report. Detailed descriptions of
processes, production, emissions, and control at eleven plants are compiled in EPA's
confidential files. State and local emission regulations and emission source
sampling and analysis methods are also discussed.
The background information has been used in a simple emission projection
model (Model IV) to determine the emission reductions that could be achieved by
the application of New Source Performance Standards.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lOENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
13. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS /This Report/
Unclassified
21. NO. Or PAGES
145
20. SECURITY CLASS (Thispage/
Unclassified
22. PRICE
EPA rorm 2220-1 (Re». 4-77) =ie.-lOUS EDITION IS OBSOLETE
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