EPA-450/3-74-026
March 1974
SULFUR MARKETS
FOR OHIO UTILITIES
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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EPA-450/3-74-026
SULFUR MARKETS
FOR OHIO UTILITIES
by
J. F. Foster, D. M. Jenkins,
H. S . Rosenberg and J. H. Oxley
Battelle Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
Contract No. 68-02-0040
Task 11
EPA Project Officer: Rayburn M. Morrison
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Qualtiy Planning and Standards
Research Triangle Park, N. C. 27711
March 1974
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This report is issued by the Environmental Protection Agency to report technical
data of interest to a limited number of readers. Copies are^vailable free of charge
to Federal employees, current contractors and grantees, and nonprofit organizations
as supplies permit - from the Air Pollution Technical Information Center, Environ-
mental Protection Agency, Research Triangle Park, North Carolina 27711, or from
the National Technical Information Service, 5285 Port Royal Road, Springfield,
Virginia 22151.
This report was furnished to the Environmental Protection Agency by the Battelle
Columbus Laboratories, Columbus, Ohio 43201, in fulfillment of Contract No. 68-02-0040.
The contents of this report are reproduced herein as received from the Battelle
Columbus Laboratories. The opinions, findngs, and conclusions expressed are those
of the author and not necessarily those of the Environmental Protection Agency. Men-
tion of company or product names is not to be considered as an endorsement by the
Environmental Protection Agency.
Publication No. EPA-450/3-74-026
11
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TABLE OF CONTENTS
EXECUTIVE SUMMARY ix
Definition of the Problem. ix
Marketing Experiences from Other Industries x
United States Utilities x
Japanese Industry x
Fossil Fuel Industry . x
Smelters xi
Local Markets for By-Products xi
Sulfur or Sulfuric Acid xii
Gypsum. '. xii
Fertilizer xii
Other Products .xiii
New Ventures . xiii
Total Local Market xiii
By-Product Market Potentials Outside Ohio xiv
New Uses for Sulfur XV
Suggested Marketing Methods for Utilities XVi
INTRODUCTION 1
REVIEW OF THE TECHNOLOGICAL SITUATION 4
Sulfur Emissions from Ohio Utilities 4
Properties of By-Products 7
Sulfur Dioxide 8
Sulfuric Acid 8
Elemental Sulfur 9
Sulfur-Containing Solids 9
iii
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TABLE OF CONTENTS
(Continued)
Page
Sulfur Dioxide Recovery Processes Under Development 10
Process Requirements and Capabilities 10
Demonstration Plants for SO^ Removal 11
Characteristics of Processes in the
Demonstration Plants 11
Magnesia Scrubbing 12
Sulfite-Bisulfite Scrubbing with Thermal
Regeneration 12
Sulfite-Bisulfite Scrubbing with Electrolytic
Regeneration 15
Catalytic Oxidation 17
Estimated Costs 19
U.S. MARKETS FOR SULFUR-CONTAINING COMPOUNDS 20
Sulfur 20
Supply 20
Supply Economics 22
Major Uses for Sulfur 23
Non-Acid Uses for Sulfur 25
Carbon Disulfide 25
Rubber Processing 26
Minor Uses 27
Summary of Sulfur Markets. . 28
Sulfuric Acid 29
Supply and Demand in the North Central States 29
Supply and Demand in Ohio 29
Central Ohio 30
iv
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TABLE OF CONTENTS
(Continued)
Page
Northern Ohio 30
Southern Ohio 33
Demand According to End Use. 35
Fertilizer 35
Petroleum Refining. ..... . 39
Titanium Dioxide 40
Steel Pickling. 40
Hydrofluoric Acid 41
Feasible Market Area for Ohio Utilities 41
Gulf Coast Markets 41
Nearby Markets. ..... 43
Summary of Sulfuric Acid Markets 43
Gypsum 45
Applications and Demand 45
Market Growth 47
Ohio Markets 47
Marketing Considerations ....... 49
Discussion of Available Gypsum Markets ... 50
Ammonium Sulfate. . 51
Applications 51
Supply 52
Consumption 52
Discussion of Ammonium Sulfate Markets 53
Sodium Sulfite 54
Sulfur Dioxide 55
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TABLE OF CONTENTS
(Continued)
Page
MARKETING PRACTICE FOR BY-PRODUCT SULFUR COMPOUNDS .... 56
Utilities Experience in the United States 56
Illinois Power 57
Boston Edison and Potomac Electric Power. . 57
Philadelphia Electric 58
Northern Indiana Public Service ... 60
Markets in Japan for By-Product Sulfur 60
Installations for Recovery of By-Product Sulfur 61
Elemental Sulfur 63
Sulfuric Acid 63
Sodium Sulfite . 64
Calcium Sulfate (Gypsum) and Calcium Sulfite .... 64
Ammonium Sulfate 65
By-Product Specialties 65
Significance of Japanese Experience for Ohio Utilities. . 66
Sulfur Recovery from Fossil Fuel Processing 67
Natural Gas Producers 68
Petroleum Refining 68
Coke Production . 68
Development of Technology and Markets by Smelters 69
Technology of Ore Smelting 69
Smelter Marketing Experience 72
Eastern United States 72
Canadian Successes 73
Vi
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TABLE OF CONTENTS
(Continued)
Page
CONCLUSIONS AND RECOMMENDATIONS 75
ACKNOWLEDGMENTS 77
LIST OF TABLES
Table 1. Summary of 1975 Regulations in Selected Regions .... 2
Table 2. Selected Group of Major Coal-Burning Power
Plants in Ohio 5
Table 3. Uncontrolled Sulfur Dioxide Emissions From
Selected Group of Ohio Power Plants in 1971 6
Table 4. Estimated Sulfur Balance In Selected States, 1971. ... 24
Table 5. Production of Sulfuric Acid In Ohio 31
Table 6. Ohio Sulfuric Acid Plants 32
Table 7. Sulfuric Acid Plants in Neighboring States 34
Table 8. Sulfuric Acid End-Use Pattern, 1970 36
Table 9. 1972 Sales Of Gypsum And Gypsum Products -- East
North Central Census Region 46
Table 10. U.S. And Ohio Gypsum Statistics 48
LIST OF FIGURES
Figure 1. Magnesia Scrubbing With Sulfur Dioxide Recovery 13
Figure 2. Sulfite-Bisulfite Absorption Of Sulfur Dioxide
With Thermal Regeneration 14
Figure 3. Sulfite-Bisulfite Scrubbing With Electrolytic
Regeneration 16
Figure 4. Catalytic Oxidation (Retrofit Case) 18
Figure- 5. Sulfuric Acid Shipping Cost 44
Vll
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EXECUTIVE SUMMARY
Definition of the Problem
The 27 coal-burning steam-electric plants selected by EPA as
the study sample of important plants in Ohio had 92.5 percent of Ohio's
total generating capacity in 1970, and consumed 97 percent of the coal
burned for electric power generation. Sulfur dioxide emissions from
these plants were estimated at 2.4 million tons in 1971. Projected un-
controlled emissions of SO for this group in 1975 will be 3.4 million
tons. Although it is doubtful that all these utilities would choose to
recover the total emission of sulfur dioxide as salable by-products,
these estimates show the large amounts that might be available for mar-
keting.
A variety of processes have been conceived and tested for
removing sulfur dioxide from combustion off-gases similar to those
emitted by these Ohio utilities. Some processes absorb the sulfur dioxide
in a slurry or a solid which has little value and is discarded after use.
Other processes are designed to produce salable by-products. This study
is concerned with identifying potential markets for such by-products.
The possible by-products include sulfur, sulfuric acid made
from recovered sulfur dioxide, pure liquefied sulfur dioxide, calcium
sulfate (gypsum), sodium sulfite, and ammonium sulfate. Sulfur can be
stored and then converted easily to sulfuric acid to meet variable
demand. Sulfuric acid is a basic industrial chemical of wide usefulness
but costly to store to meet fluctuating demand and relatively expensive
to transport. Liquefied sulfur dioxide has expanding specialty uses in
relatively small quantities. Gypsum, sodium sulfite, and ammonium sulfate
are solids with limited fields of use in wallboard, paper manufacture, and
fertilizer, respectively. All these sulfur-containing materials tend to
be in plentiful supply already, although the utility contemplating their
recovery has a potential competitive advantage of being able to dispose
of them at a price selected to minimize net disposal cost. This selected
price may give lower net cost than other disposal routes.
ix
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Marketing Experiences from Other Industries
Four industries with experience pertinent to the marketing of
sulfur by-products by Ohio utilities are (1) United States utilities with
demonstration plants for sulfur removal; (2) Japanese industry, where
sulfur has been in short supply in the past; (3) natural gas producers
and petroleum refiners, who must remove sulfur from their products; and
(4) smelters of metal sulfide ores, with substantial concentrations of
sulfur dioxide in their stack gases.
United States Utilities
Present demonstration plants for recovery of sulfur from utility
stack gases have used the general approach of marketing sulfur products
directly to or through an established chemical company. The vendor of
the flue gas desulfurization equipment usually arranges the contacts
between the equipment purchaser and the chemical company.
Japanese Industry
The recovery of sulfur by-products has been prompted by the
high cost of imported sulfur. The following products have been marketed:
sulfur, sodium sulfite, sodium sulfate, sulfuric acid, and gypsum. Now,
Japan is in a period of installation of emission controls that augurs a
surplus of sulfur. Japanese attempts to alleviate potential surpluses
are pointed to production for predictably expanding markets, recovery
processes with flexibility to produce more than one product, and an
accelerated search for new products or novel uses.
Fossil Fuel Industry
The fossil fuel industries recover a side stream of hydrogen
sulfide, which is convertible to sulfur, sulfuric acid, and other products.
Thus they have the flexibility to supply several markets. Alternatively,
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sulfur can be stored as a stable solid material at minimum cost, and
recovered for future sale as markets change. These options are not as
available to Ohio utilities, although a tie-in could be arranged to
Interchange sulfur dioxide from a utility with hydrogen sulfide from a fossil
fuel processor to make sulfur. These two gases combine chemically and form
elemental sulfur, to be used for further processing, storage, or sale.
Smelters
Smelting companies sometimes use the services of an established
chemical company to market the sulfuric acid that is a by-product of
their operations. However, the special situation facing Consolidation
Mining and Smelting Company (Cominco) of Canada at their plant in Trail,
British Columbia,prompted this company to take direct and aggressive action
in the development of expanded markets for sulfur products . Cominco sells
SO. produced at Trail as far away as Glen Falls, New York; Hobbs, New
Mexico; and Alaska. Cominco sulfuric acid is marketed mostly on the West
Coast of the United States, but a significant amount is transported and
sold in Calgary, despite the fact that sulfur recovered from natural gas
is available there in tremendous quantities. For many years ammonium
sulfate was shipped from Trail to the Orient for use as a fertilizer.
Copper Hill in Tennessee currently ships and markets a portion of their
production 400 miles or more in jumbo tank cars.
Local Markets for By-Products
The most attractive market for Ohio utilities is obviously
those industries within the state itself that consume significant amounts
of sulfur or sulfur-containing products.
Sulfur markets in nearby states may be more limited.
If sulfur abatement regulations similar to Ohio's are enforced in these
neighboring states, any pollution abatement technology feasible for an Ohio
utility would also be feasible for competing utilities across the state
boundaries. Although sulfur oxide regulations in some adjacent states may
enable utility power plants there to use low-sulfur or cleaned coal in
place of sulfur dioxide flue-gas cleaning systems, the total amounts of
xi
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sulfur that could be recovered in all adjacent states is large compared
with the markets currently available for by-product sulfur compounds.
Sulfur or Sulfuric Acid
There appears to be a market in and near Ohio for about 120,000
•ft &
long tons of elemental sulfur (269,000 tons SO,, equivalent) from Ohio
utilities. This market is about 11 percent of estimated 1971 emissions
and 8 percent of estimated uncontrolled 1975 emissions from the major
Ohio utilities.
Alternatively, there appears to be a market for about 150,000
tons sulfuric acid (98,000 tons S0_ equivalent) in northern Ohio and up
to 150,000 tons acid in southern Ohio. Since sulfuric acid is the major
end use of elemental sulfur, production of by-product acid would reduce
the sulfur markets estimated in the preceding paragraph. Furthermore,
not all acid can be supplied as by-product. Some sulfur-burning capacity
for acid manufacture will be needed to provide flexibility. The total
potential market in Ohio for utility by-product acid of 300,000 tons would
consume about 6 percent of the estimated uncontrolled emissions from
Ohio utilities in 1975.
Gypsum
There is a limited potential market in Ohio for by-product
gypsum if it is of wallboard quality. The annual market is estimated
at about 350,000 tons gypsum (130,000 tons S0_ equivalent or about 4 per-
cent estimated uncontrolled 1975 emissions). To minimize transportation
costs, gypsum would best be recovered at power plants between Toledo and
Cleveland.
Fertilizer
Ammonium sulfate is a relatively low-analysis fertilizer. Except
when it is specially treated to increase the particle size, it has the
* All quantities of elemental sulfur are given, according to custom, in
"long tons" of 2240 pounds. Quantities of other materials are given in
conventional "tons" of 2000 pounds, sometimes referred to as short tons.
XI i
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additional disadvantage of baing hard to handle and apply. Unless Ohio
soils become deficient in sulfur, use of ammonium sulfate is unlikely to
grow. There are very limited areas of potentially sulfur-deficient soils
in Ohio, and widespread sulfur deficiency will probably not be recognized
in most of Ohio until at least 5 years after virtual elimination of sulfur
emissions from Ohio and Indiana utilities. The markets for ammonium
sulfate are expected to remain essentially constant through 1983.
By-product ammonium sulfate supply in and near Ohio appears
more than adequate to satisfy consumption. Ohio consumption is estimated
at a maximum of 70,000 tons (equivalent to 17,000 tons S02). This could
be supplied by a single 200 to 250 MW generating station. Considering
the large supply of by-product ammonium sulfate already manufactured in
and near Ohio, and the limited demand, it appears that ammonium sulfate
is not a profitable by-product for sale by most Ohio utilities.
Other Products
The markets for sodium sulfite and liquid sulfur dioxide in and near
Ohio are too small to be of significance for disposal of by-product sulfur
from Ohio utilities.
New Ventures
One speculative venture, which could provide a significant market
for by-product sulfur or sulfuric acid in Ohio would be the establishment
of a phosphate fertilizer industry in Ohio. Such a venture, sized to meet
Ohio's phosphate fertilizer demand, would consume about 230,000 tons of
sulfur dioxide (about 7 percent of estimated 1975 uncontrolled emissions)
in the form of sulfuric acid. A phosphate fertilizer operation in Ohio
might cause significant water pollution problems. These factors, as well
as venture economics, merit more detailed investigations.
Total Local Market
Summarizing, it appears that there is an opportunity to sell up
to 12 percent of the sulfur expected to be emitted from Ohio utilities in
1975 in local markets. This sulfur would be sold in the form of elemental
sulfur, sulfuric acid, and gypsum. If a phosphate fertilizer industry
xiii
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were established in Ohio, a new market for sulfuric acid equivalent to
about 7 percent of uncontrolled 1975 emissions would be generated. This
alternative is highly speculative, however.
By-Product Market Potentials
Outside Ohio
One way to market additional sulfur recovered from Ohio
utilities would be to ship it to the Gulf Coast. Gulf Coast markets
could absorb virtually all sulfur potentially recoverable from Ohio
utilities for manufacture of the sulfuric acid that is used there in
making phosphate fertilizers. The production of sulfuric acid now depends
largely on sulfur mined by the Frasch process, which would be displaced,
if the technical and economic feasibility of recovering sulfur from Ohio
utilities for sale on the Gulf Coast can be demonstrated.
There are numerous out-of-state utilities that also will be
burning high sulfur coal in states between Ohio and Gulf Coast markets.
These also might recover by-product sulfur. Their transportation costs
would be lower with a consequent competitive advantage for shipments of
sulfur in that direction. To examine this competition, a crude estimate
was made of the supply and demand for sulfur in selected states closer
than Ohio to the Gulf Coast fertilizer manufacturers where the pollution
control regulations are expected to require stack gas desulfurization.
The results of this analysis indicate that, even if significant amounts
of sulfur were recovered by utilities nearer to the Florida and Louisiana
markets, there would still be a potential market for sulfur from Ohio
utilities. According to this analysis, there is a net estimated surplus
of only 230,000 long tons in a market of 4.5 million lone tons, assuming
100 percent recovery by all utilities in the selected states exclusive of Ohio.
However, many of these out-of-state utilities may adopt throw-away
systems instead of systems that recover by-products. In order to penetrate
this market, Ohio utilities would have to deliver sulfur on the Gulf
Coast at prices competitive with Frasch sulfur.
This analysis has included the production of by-product sulfur
recovered at petroleum refineries and from natural gas, plus by-product
xiv
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smelter acid, but has not assumed any growth in recovery of elemental
sulfur from petroleum refineries, any nonacid uses for sulfur, nor any
projected growth in sulfur consumption.
New Uses for Sulfur
There are a number of potential new uses for sulfur which are
in various stages of development, but none of these have yet reached
commercialization and they are not expected to have significant commercial
impact before 1985. Although some of these applications may eventually
provide outlets for by-product sulfur recovered by the electric utilities,
it would be unrealistic to consider such applications in planning emission
controls from currently existing power generation stations and plants now
under construction.
One of the largest and most promising potential markets for
sulfur is in road building. Research at Shell Canada indicates that a
mixture of 13.5 percent sulfur, 6 percent asphalt, and 80.5 percent sand
can be used as a base course in highway construction, replacing 3 times
the thickness of gravel with economic advantage in many areas. It is
estimated that the possible Canadian market for sulfur/asphalt road
building materials could require more than 600,000 long tons of sulfur annually.
Shell Canada is actively trying to develop markets for sulfur in road
construction.
Another potential use for sulfur is in the manufacture of rigid
foams which would have application as insulation in construction and
possibly in subsoil in Arctic areas. Technology has been developed for
producing rigid sulfur foams with densities ranging from 7 to 30 pounds
per cubic foot. The annual Canadian market potential for sulfur in this
application has been estimated to be about 300,000 long tons.
A third possible application may be sulfur-concrete mixtures.
Sulfur-concrete is expected to find use initially in precast products,
concrete pipes, ground anchors, street curbs, traffic barriers, etc.
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Other possible uses for sulfur which may have commercial sig-
nificance include use in traffic paints; use as an impregnant for porous
materials like concrete, ceramics, and wood; use in a new granulated form
of gypsum as a soil conditioner, as a reinforcing agent for polymers,
and for incorporation into the polymer molecules themselves.
Suggested Marketing Methods for Utilities
At present the most expedient course of action for many Ohio
utilities may be to seek a marketing agreement with a company already
having the necessary distribution system and marketing expertise, rather
than to build immediately for themselves the necessary expertise to
market chemical by-products. By virtue of their sulfuric acid operations
in and near Ohio, obvious candidates for marketing by-product acid from
Ohio utilities include Allied Chemical and Du Pont. For marketing ele-
mental sulfur, not only these companies but also other acid manufacturers
and sulfur producers such as Texasgulf and Freeport Minerals could be
considered. Other producers should be considered for marketing of the
other possible by-products.
However, those utilities that are capable of assuming a more
active role in marketing, in the face of a projected sulfur surplus,
are more likely to preempt the markets that are potentially
available. For instance, a substantial part of the uncontrolled emissions
of SO- from all Ohio utilities probably could be sold if all the recog-
nizable local and Gulf Coast markets for sulfuric acid, sulfur, and
fertilizer were aggressively pursued.
Finally, a more active research and development effort in the
;
search for new products utilizing sulfur should be considered by the
larger utilities or cooperatively on a group basis.
The developments at the Trail smelter of Cominco over the past
50 years are an example of the success possible with a dedicated company
effort.
XVI
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TOPICAL REPORT
on
SULFUR MARKETS FOR OHIO UTILITIES
to
STRATEGIES AND AIR STANDARDS DIVISION
OFFICE OF AIR AND WATER PROGRAMS
ENVIRONMENTAL PROTECTION AGENCY
September 25, 1973
by
J. F. Foster, D. M. Jenkins, H. S. Rosenberg,
and J. H. Oxley
Prepared as Task 11
Task Order Contract
No. 68-02-0040
from
BATTELLE
Columbus Laboratories
INTRODUCTION
The Strategies and Air Standards Division of the Environmental
Protection Agency Office of Air and Water Programs is sponsoring a series
of concurrent studies to generate technical information needed by State
agencies to develop power plant control strategies which are consistent
with EPA's clean fuels policy. Not only must Federal regulations on
new plants be met, but there are also State regulations on new and old
plants to be considered, and, as shown in Table 1, these vary from state
to state.
This Battelle report discusses possible actions open to Ohio's
electric utilities for disposing of sulfur-containing materials accumu-
lated as products of the removal of sulfur dioxide from stack gases in a
form for reuse as a sulfur-containing by-product. Two options not
considered here, but treated in other studies, are (1) to burn low-sulfur
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TABLE 1. SUMMARY OF 1975 RESTRICTIONS ON SULFUR EMISSIONS FROM URGE STEAM-GENERATION PLANTS IN SELECTED REGIONS
1970 Fossil Fuel Use
(IP12 Btu)
State
Coal
Oil
Gas
1975 Sulfur Emis-
sion Restrictions
(b)
Remarks
Georgia
178.1
West Virginia 348.8
Kanawha Valley
Priority I & II
Priority III
Ohio 794.6
Priority I
Priority II
Priority III
Kentucky 396.9
Priority I
(Louisville)
Priority II
Priority III
9.5
0.7
4.1
0.6
59.4
0.4
13.9
8.6
3.07. S
1.6 Ib SO,/MM Btu
2.7 Ib SO,/MM Btu
3.2 Ib SO,/MM Btu
1.5% S oil
2.07. S coal
1.0 Ib S02/MM Btu
1.6 Ib SO /MM Btu
3.1 Ib SO^/MM Btu
1.2
0.8
2
1.5
3.5
Ib SO,/MM
Ib SO,/MM
0 Ib SO,/MM
Ib SO,/MM
Ib/MM Btu
2.0 Ib S02/KM
Btu coal
Btu oil
Btu coal
Btu oil
coal
Btu oil
Approved. New sources 0.8 Ib SO,/MM Btu oil;
1.2 coal.
Approved. Priority I Regions: Weirton-
Wheeling; Cumberland. Priority II: Parkers-
burg. Priority III: all other. Fuel
restrictions are recommendations, not
regulations.
Approved. All regions must meet Priority I
levels by July 1, 1978. Priority I Regions:
Cincinnati^), Cleveland; Marietta^); North-
west Ohio; Steubenville; Toledo; Youngs-
town^); Zanesville.
Priority II: Dayton; Mansfield-Marion.
Priority III: Columbus; Portsmouth-
Ironton; Sandusky; Wilmington-Chillicothe-
Logan.
Approved. Priority I Region is Louisville and
was granted an extension to July 1977 to
enforce population and meet standards.
Priority II: Evansville; Paducah; Cincin-
nati. All but Cincinnati given until July
1978 to meet secondary standard. All other
regions are Priority III.
t-o
(a) Fossil fuel consumed only by steam-electric plants.
consumption.
(b) These restrictions are indicated on the basis of information presently available to Battelle-Columbus.
some of them might be changed between now and 1975.
(c) Classified Priority II by EPA, I by Ohio.
Does not include residential, commercial, or industrial
However,
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synthetic or natural fuels, or (2) to absorb sulfur dioxide from stack
gases into a throw-away product.
The general objective of the Battelle assignment was to assemble
and interpret data on potential sulfur markets which can suggest the form,
scope, and direction of the marketing strategy that must be developed by
each utility for its own use.
The three specific objectives of this study were (1) to identify
by-products that could be derived in significant quantities from sulfur
dioxide separated from stack gases; (2) to describe and discuss markets
that presently exist for these by-products; and (3) to compare by-product
sulfur markets developed in other industrial sectors which show approaches
to the problems facing the electric utilities.
The sulfur-containing by-products considered attractive
economically and potentially recoverable from utility stack gases in
order of importance are sulfuric acid, elemental sulfur, liquid sulfur
dioxide, calcium sulfate, ammonium sulfate, and sodium sulfite.
The industrial classifications of by-product sulfur producers
with experience pertinent to utility problems, as selected for this
study, are (1) the American electric utilities with demonstration sulfur-
removal facilities installed or planned; (2) Japanese industries, includ-
ing some electric power plants with sulfur emission controls; (3) the
fossil-fuel industries of United States and Canada, including production
of natural gas, petroleum refining, and coke production; (4) the smelting
industry processing sulfur-containing ores of copper, lead, and zinc.
The information collected concerning these industries is con-
sidered in terms of its application to the particular group of 27 coal-
burning steam-electric generating plants of Ohio utilities selected by EPA
as the representative sample of important plants in Ohio.
This study does not consider any individual power plant of the
Ohio group as to its own available or projected markets and marketing
strategy. However, the general conclusions are made as specific as
possible, so that they may be applied by the individual utilities while
developing their unique, plans for action.
It may be for a particular utility that by-product sulfur
recovery and sale either is not practical or is not a preferred option.
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Nevertheless, this report is intended to provide a basis for a preliminary
appraisal of options, as well as background information to guide more
detailed studies that should be developed before a final decision is
reached.
REVIEW OF THE TECHNOLOGICAL SITUATION
Sulfur Emissions from Ohio Utilities
Twenty-seven major utility power plants that are responsible
for about 61 percent of coal-fired utility S0« emissions in the Air
Quality Control Regions of Ohio (ACQR) grouped by power system are listed
in Table 2. A code number has been assigned to each plant for reference
in the following discussion. The name-plate generating capacity in 1970
and the coal used with its percentage of sulfur in 1970 are also given for
reference. More recent data are used below for 1971 emission calculations.
The planned capacity increase listed for each plant in the period between
1971 and 1975 is also used as given to calculate the increment in emissions
by 1975.
An estimate of total emissions of sulfur dioxide from the
electric power plants in each Air Quality Control Region wholly or par-
tially within the State of Ohio is presented In Table 3. The totals in
Column A of the table include one or two nonutility power plants wrth
significant amounts of emissions, power plants outside of Ohio but within
the interstate regions, and several municipal plants with significant
emissions. The fifth column shows a subtotal by region of the emissions
from those of the 27 selected plants within each region. To the right of
0
each subtotal are shown the calculated emissions from each of the 27 plants
identified by code number. Finally, at the extreme right are given the
calculated plant increases in emission until 1975 with the amount for
individual plants identified by code number. Thus, these data show that
about 4 million tons of sulfur dioxide are emitted in the Ohio AQCR's of
which about 2-1/2 million tons was emitted in 1971 by the 27 plants under
consideration. The estimates of the planned increases until 1975 add
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TAB IE 2. SELECTED GROUP OF MAJOR COAL-BURNING POWER PLANTS IN OHIO
System
Cincinnati Gas &
Electric Company
Cleveland Electric
Illuminating Co.
Columbus & Southern
Ohio Elec. Co.
Dayton Power
& Light Company
Ohio Edison Company
Ohio Power Company
Ohio Valley
Electric Corp.
Toledo Edison Co.
Total
Code
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Power Plant
W. C. Beckjord #
Miami Fort
Ashtabula
Avon Lake
Eastlake
Lake Shore
Conesville
Picway
Poston
Walnut
0. H. Hutchings
F. M. Tait
J. M. Stuart
R. E. Burger
Edgewater
Gorge
Niles
W. H. Sammis
Toronto
Cardinal
Muskingum
Philo
Tidd
Gavin
Kyger Creek
Acme
Bay Shore
Nameplate
Capacity Planned
Location
1970, Capacity Increase, AQCR
mW mW (year) No.
1-6 1,221
519
456
1,275
577
514
433
230
232
75
414
444
610
544
192
87
250
1,680
315
1,180
1,466
500
222
—
1,086
337
639
. 15,504
.3 500- (75)
.2 500- (75)
.0
.0
.0 680- (72)
.0
.5 842-(73)
.8
.0
.0
.0
.1
.2 1830(71-74)
.0
.9
.5
.0
.5 623-71
.8
.0
.8
.0
.2
1300-74
.3
.0
.5
.6
79
79
178
174
174
174
183
176
179
176
173
173
103
181
174
174
178
181
181
181
179
183
181
103
103
124
124
Priority
(S02)
II
II
II
I
I
I
IA
III
II
III
II
II
III
I
I
I
II
I
I
I
II
IA
I
III
III
I
I
(a)
(a)
(a)
(b)
(a)
(b)
(b)
(b)
(b)
(a)
(a)
(b)
(b)
County
Clermont
Clertaont
Ashtabula
Lorain
Lake
Cuyahoga
Coshocton
Pickaway
Athens
Franklin
Montgomery
Montgomery
Brown
Belmont
Lorain
Summit
Trumbull
Jefferson
Jefferson
Jefferson
Morgan
Muskingum
Jefferson
Gallia
Gallia
Lucas
Lucas
1970 Average
Coal Use Percent
(103 tons) Sulfur
3,038
969
942
1,977
1,780
1,271
1,303
381
732
129
897
1,010
348
1,276
311
211
557
3,863
410
3,020
3,683
984
581
2,803
350
1,480
34, 306
2
3
4
2
2
2
4
3
2
3
1
1
2
3
2
3
3
2
2
2
5
3
2
4
2
2
.81
.71
.24
.66
.30
.61
.63
.35
.01
.11
.21
.57
.23
.67
.63
.42
.34
.64
.39
.98
.02
.32'
.94
.26
.45
.22
(a) Sulfur emissions below primary ambient air quality standard. Federal Register Vol. 37, No. 145, Thursday, July 27, 1972.
(b) Sulfur emissions below secondary ambient air quality standard. Federal Register Vol. 37, No. 145, Thursday, July 27, 1972.
Equivalent to 92.5% of total generating capacity and 97%.of total coal used in Ohio for electric power generation.
(c)
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TABLE 2 . UNCONTROLLED SULFUR DIOXIDE EMISSIONS FROM SELECTED GROUP
OF OHIO POWER PLANTS IN 197l(a,b)
(1000 T/yr)
Total Regional
Air-Quality Control Region Coal-Fired
No.
079
103
124
173
174
176
177
178
179
181
Name
Cincinnati
Hunt ing ton WV
Toledo
Dayton
Cleveland
Columbus
NW Ohio
NW Pa - Youngs town
Parker sburg-Marietta
Steubenville
183 Zanesville
Totals 1971
S02
Priority
II
IIl(c)
I
II
I
Hl(c)
I
II
II
I
IA
Totals 1975
Utility
Emissions
437
378
591
59
464
29
3
310
474
823
388
4006
4967
Total in
Each AQCR From
27 Selected
Utilities
334
254
81
50
433
29
0
95
415
478
388
2427
3388
Emissions From Planned Increases W)
Individual Plants, Until 1975,
Code No.(b)- Amount Code No.(b) - Amount
#1-171; #2-163 + #2-156
#13-15;#24-0;#25-239 +#24-70, #13-45
#26-19 ;#27-62
#11-20; #12-30
#4-143 ;#5-200;#6-71; + #5-235
#15-19; (#16-16) (e'
#8-21; #10-8
<
None
#3-61; #17-34
#9-25; #21-390
#14-83; #18-199; #19-21; + #18-74
#20-142; #23-33
#7-317 ;#22-71 +#7-616
961
(a) Derived from "Input data by regions for power plant analysis": Appendix C of Draft Reports for each AQCR
"Modeling Analysis of Power Plants for Compliance Extensions. -- AQCR." Walden Research Corp., for Source
Receptor Analysis Branch, Monitoring and Data Analysis Division, of OAQPS, OAWD, EPA. Various dates, 1973.
(b) See Table B-2.
(c) Priority III Regions calculated from coal consumption and average sulfur in coal.
(d) Estimated from nameplate capacity.
(e) No by-product recovery is planned for Plant #16, which will be discontinued in 1981.
-------
almost another million tons to give a total for all Ohio regions of about
5 million tons of SO. emissions. It appears that these totals represent
emissions that will potentially be a source of sulfur by-products from
Ohio competing for appropriate markets or disposal procedures within and
outside the state boundaries.
The calculated amounts of emissions for individual power plants
in Priorities I and II in 1971 were from EPA excerpts of reports labeled
"Input Data AQCR Power Plant Analysis" provided by the EPA Project Monitor.
The emissions for Priority III regions were calculated from plant fuel
consumption and sulfur content data for 1971 reported on Federal Power
Commission Form 67 by assuming that 95 percent of sulfur in the coal
appears as sulfur dioxide in the flue gases.
The estimates of emissions from new units to be placed in service
were calculated as the ratio of the name-plate capacities of the new and
old units in the same plant times the 1971 annual SO. emission of the old
plant. Finally, the estimated emissions for the new Gavin Plant (No. 24)
were derived as a ratio of its name-plate capacity to name-piate capacity
of Kyger Creek Plant (No, 25) in the same region and same county, assuming
equal efficiency of coal consumption and 1 percent sulfur in the coal,
which was based on an estimate received from EPA.
Properties of Bv-Produets
o
The Ohio plants to which these studies ere directed will be
burning high-sulfur coal while discharging the gases from the com-
bustion process into the furnace stack end then into the atmosphere.
Almost all the sulfur content of these gases is gaseous sulfur dioxide
(802)1 Plus a ffluch smeller amount o£ sulfur trioxide (§03). These two
products are formed from over 90 percent of the original sulfur in the
coal, and the remaining sulfur stays in the eoel aeh. To stay within
permissible limits a major pert (generally ebove 85 percent for Ohie
coals) of the gaseous S02 must be separated from the combustion geses
and discarded in an acceptable ferm or converted te by-preduets with
useful properties.
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Sulfur Dioxide
Sulfur dioxide is the predominant by-product from which all
others are derived. It is sold also as a primary by-product for use
as a preservative and bleach in foods, for solvent refining of lub-
ricating oils, for preparation and bleaching of sulfite pulp and
paper stock, for conversion to sulfur trioxide, and as a disinfectant
and fumigant.
It is a gas which is easily liquefied for storage or ship-
ment under a pressure of about 35 psig at room temperature. As a dry
liquid it is noncorrosive to steel pressure containers. The gas is
easily soluble in water or dilute acid to form an unstable solution of
sulfurous acid, which can be decomposed by heating to drive off sulfur
dioxide gas from the solution.
Salfuric Acid
Sulfur dioxide is oxidized by air in the presence of a
catalyst to form sulfur trioxide (SO^), which combines spontaneously
and irreversibly with water vapor to form sulfuric acid. With carefully
controlled conditions of temperature, flow rate, and composition of the
reacting mixture, 97 percent of the input of sulfur dioxide can be con-
verted in a one-pass sulfuric acid plant. Starting with pure S02 and
pure dry air, sulfur acid of high purity can be produced from the 803.
A range of high acid concentrations to serve any market is available.
The usual practice is to absorb the SO-j in 100 percent sulfuric acid
and then dilute this solution back to 100 percent acid with water.
Pure concentrated sulfuric acid cannot always be made from
by-product sulfur dioxide in stack gases because of possible economic
limitations on the removal of fly ash and water vapor completely from feed
to the by-products acid plant. Traces of metals and carbon from small
amounts of the dark-colored ash may be carried into the acid, which then
cannot meet purity and color specifications for some applications. Water
vapor formed as a combustion product may dilute the acid to a concentra-
tion less than the usual commercial grades having nearly 100 percent acid.
The process to be used by a utility in producing sulfuric acid should
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therefore be examined to be sure its product satisfies the intended
market.
Elemental Sulfur
Sulfur dioxide reacts with reducing agents with loss of its
oxygen and formation of elemental sulfur under appropriate reaction conditions,
The common reducing agents contain carbon, hydrogen, or both. They include
natural gas (methane), carbon monoxide, coke, hydrogen gas, and hydrogen
sulfide. Any of these might be used by a utility to convert recovered S0_.
The choice would ultimately fall on the reducing agent which imposed the
lowest processing cost. Hydrogen sulfide and natural gas are the only re-
ductants which have been used on a large commercial scale. Coke also has
been used commercially with satisfactory results.
Elemental sulfur has properties which make it easy to handle and
store. It is an inert solid that does not deteriorate in open storage. It
can be prepared in high purity. It is used in the rubber industry and as a
fungicide. The largest use is for conversion to sulfur dioxide for manu-
facture of sulfuric acid.
Sulfur-Containing Solids
Various solid materials can be prepared as by-products of
sulfur recovery or as intermediates for further treatment. Solids may
be desirable because they can be separated from the water portion of
the wash liquid by centrifuging or filtration as part of the recovery
process. The particular solid material depends upon the material used
in the process as an absorbent to react with the sulfur dioxide in the
flue gas.
Each individual absorbent gives a different solid by-product
or intermediate, but all have the common property of being an alkali to
neutralize the acid solution of sulfur dioxide. Thus, the reacting
alkalies may be calcium-containing limestone, lime, or slaked lime,
all of which produce calcium sulfite or calcium sulfate as the solid
by-product, or other calcium-free alkaline materials including ammonia,
sodium hydroxide and soda ash, and magnesia. Each of these reactants can
produce one or more useful solid by-products, or intermediate products
that are processed further to regenerate sulfur dioxide and recover the
-------
10
original alkali absorbent. The calcium sulfite and calcium sulfate products
obtained by absorption with lime have received much attention, because the
low cost of the absorbents should be reflected in relatively low cost by-
products. Calcium sulfate from mined deposits is used in plaster board for
wall construction. Calcium sulfate also might find some use as a soil
conditioner, or it may be a throw-away product used for land-fill. Calcium
sulfite can be oxidized to calcium sulfate, or it may have some use as a
filler in plastic materials. The other solids formed from absorbents
ammonia, magnesia, or sodium hydroxide are intermediates which are regen-
erated to recover the relatively costly absorbent plus sulfur dioxide, so
that the absorbent can be reused, and the sulfur dioxide can be converted to
sulfuric acid.
These examples indicate the large variety of processes which have
been investigated for sulfur dioxide removal from flue gases, and emphasize
the number of by-products that are possible. The variety of available
processes and diverse nature of the by-products imposes the necessity for
a difficult decision by each Ohio utility to select as far as possible a
process that will be suited to its own needs at minimum cost.
Sulfur Dioxide Recovery Processes Under Development
Process Requirements and Capabilities
The optimum SC- recovery process for utilities would give adequate
emission control without significantly increasing the cost of electric power,
negligible cooling of the stack gas to avoid loss of plume buoyancy, and an
easily storable and concentrated product with a stable and attractive market.
However, generally there must be some economic trade-offs between process
costs and by-product income (or disposal costs). Proposed processes can
produce either elemental sulfur, sulfuric acid, liquid S0_, ammonium sulfate
(a fertilizer material), calcium sulfate (gypsum), or sodium sulfite or sulfate.
Some are limited to one product, others make two, and in some the product type
is optional. Most of the SCL recovery processes now under commercial develop-
ment in the United States produce either sulfur or sulfuric acid. The
recovered SO- can then be converted to sulfur or other sulfur-containing
-------
11
products. These SO recovery processes include magnesia scrubbing, sulfite
scrubbing with thermal or electrolytic regeneration, and catalytic oxidation.
Demonstration Plants for S02 Removal
The EPA has given financial assistance to build and operate
demonstration plants for four processes at steam-electric plants. These
are (1) the Chemico/Basic magnesia scrubbing process now in operation on
an oil-fired boiler at Boston Edison's Mystic Station and scheduled for
demonstration on a coal-fired boiler at Potomac Electric Power's
Dickerson station. (2) the Davy Powergas/Allied Chemical sulfite
scrubbing process with thermal regeneration at Northern Indiana Public
Service Company's Mitchell Station; (3) the sulfite scrubbing process
with electrolytic regeneration at a Wisconsin Electric power station
in Milwaukee; and (4) the Monsanto catalytic oxidation process at
Illinois Power's Wood River station. The magnesia scrubbing and
catalytic oxidation installations at Mystic station and Wood River
station have been completed, but no significant operating experiences
have been obtained up to the date of this report. The two sulfite
scrubbing installations are scheduled to start up in 1974. In
addition, Philadelphia Electric is installing a privately funded mag-
nesia scrubbing process at its Eddystone plant. ,
Characteristics of Processes in the
Demonstration Plants
The first three S02 recovery processes discussed above wash
the flue gas with a water slurry or solution which cools it to about
125 F. This is too low a temperature to leave the cleaned gas with
enough buoyancy to rise properly through the stack, so that some
reheating is required. The fourth process, catalytic oxidation, re-
quires heating of the flue gas above the normal discharge temperature
from existing plants. It must be preheated to about 850 F before it
contacts the catalyst for the oxidation reaction to occur.
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12
Magnesia Scrubbing. Thus far, the only commercial-sized instal-
lation of magnesia scrubbing in the United States is on the oil-fired
boiler at Mystic Station; another installation on a coal-fired boiler of
Potomac Electric Power Company is scheduled to go on stream in 1974. For
operation on flue gas from the coal-fired boiler (refer to Figure 1), the
gas is first sent to a particulate scrubber for efficient removal of fly
ash. The flue gas is then washed with fresh magnesia (MgO) slurry in an
absorber to form magnesium sulfite (MgSO-j) and some magnesium sulfate
(MgSC>4), which are centrifuged, dried, and heated (calcined) to recover
MgO and SC>2. The MgO is returned to the absorber and the S02 is used
to make high-quality sulfuric acid. The cleaned flue gas is reheated
and sent up the stack. The process advantages are minimal solid waste
disposal problems, no water pollution, and a potential credit from the
sale of sulfuric acid. However, the process is susceptible to problems
from fly ash and sulfate buildup in the system which may have to be
purged, and possible reduction of capacity for absorption of S02 by
the recycled MgO.
Sulfite-Bisulfite Scrubbing with Thermal Regeneration. Five
commercial installations of the sulfite-bisulfite scrubbing process are
already operating in the United States and Japan. In addition, the Davy
Powergas Company will install the first full-scale demonstration plant
project to treat the stack gas from a coal-fired boiler at the Mitchell
Station of Northern Indiana Public Service Company. The end product of
this plant will be elemental sulfur which will be produced in a second
step by direct reduction of the recovered S02 with natural gas, using the
Allied Chemical process.
The flue gas passes through (1) a prescrubber where it is
humidified, (2) then through an absorber where S02 is removed with
sodium sulfite solution, (3) the clean stack gas is reheated and sent
to the stack (refer to Figure 2). The scrubbing solution is regen-
erated by evaporation of water and S02 in a crystallizer which precipitates
sodium sulfite solids. The vapor product is cooled to condense out all of
the water. The pure S02 gas can be further processed to liquid S02, sul-
fur, or sulfuric acid. Condensed water is used to redissolve the sulfite
solids for recycle through the scrubber. Sulfate formed in the scrubber
cannot be regenerated and is removed from the system by discarding part
-------
13
STACK
GAS
FLY ASH
TO
WASTE
CLEAN
GAS
TO STACK
SULFUR DIOXIDE
(TO ACID PLANT)
MAGNESIA-WATER SLURRY
«—FUEL
AIR
WATER
MAGNESIA
FIGURE 1. MAGNESIA SCRUBBING WITH SULFUR DIOXIDE RECOVERY
-------
14
STACK
GAS
. COOLER
WET S02
TO STACK
DRY
•*. SULFUR
DIOXIDE
WATER
CENTRIFUGE
WATER
SODIUM
SULFITE
SODIUM SULFITE SOLUTION
FIGURE 2. SULFITE-BISULFITE ABSORPTION OF SULFUR DIOXIDE WITH
THERMAL REGENERATION
-------
15
of the scrubbing solution continuously or by selective crystallization
and removal of solid sodium sulfate. The discarded solution must be
treated to eliminate polluting effects of chemical oxygen demand on
groundwaters due to its sulfite content.
The specific advantage of the process is the simplicity of its
unit operations. The main disadvantage is its sensitivity to buildup of
contaminants (sodium sulfate, sodium thiosulfate, sodium polythionates,
and a small amount of elemental sulfur), thus necessitating discarding
some of the solution with the loss of sodium content, which must be
replenished.
Sulfite^Bisulfite Scrubbing with Electrolytic Regeneration.
Stone & Webster/Ionics are developing an alternative method for regen-
erating spent absorber solution from sulfite-bisulfite scrubbing. A
pilot-scale demonstration of this process on a 70-mw coal-fired boiler in
Milwaukee is being funded by the EPA. This process is very similar to
the one described above except for the treatment of the spent absorber
solution. In the process (refer to Figure 3) there are two recirculating
absorption stages. Alkali solution is introduced in the upper stage where
it reacts with SO- and makes sodium sulfite. This solution passes from
the upper stage to the lo'-er stage, during which a sizeable amount of the
sulfite is converted to sodium bisulfite by further absorption of S0_.
Side reactions convert some of the sulfite and bisulfite to sulfates.
The final solution containing the sulfite and bisulfite is reacted with
dilute sulfuric acid to free SO. and also form sodium sulfate. The S0?
is stripped from solution, dried, and processed to liquid SO., sulfur, or
concentrated sulfuric acid.
The sodium sulfate solution is pumped into an electrolytic
cell, which simultaneously generates alkali for recycling to the
absorber and acid for freeing the S02 from the sulfite-bisulfite
solution. Sulfate formed as a side reaction by oxidation is rejected
from a special cell configuration as pure dilute I^SO^, without the
loss of sodium ion.
This process requires a considerable amount of power to
operate the electrolytic cells so that it is most applicable to plants
having suitable amounts as off-peak loads. Although the process avoids
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16
STACK
GAS
CLEAN GAS
TO STACK
PURE
REBOILER
ELECTROLYTIC
CELL
SODIUM
SULFATE
FIGURE 3. SULFITE-BISULFITE SCRUBBING WITH ELECTROLYTIC REGENERATION
-------
17
the loss of sodium ion by producing dilute H_SO, from the sulfate formed
in the absorber, this dilute acid must either be sold or neutralized with
limestone for waste disposal.
Catalytic Oxidation. Small pilot plant demonstrations of the
catalytic oxidation process were tried in 1963 at the Seward, Pennsylvania,
plant of Pennsylvania Electric Company and in 1968 at the Portland,
Pennsylvania, plant of Metropolitan Edison Company. The first commercially
sized installation of the Monsanto Cat-Ox process was placed in operation
in September, 1972, on a coal-fired 100-mw unit of Illinois Power
Company at Wood River. The system (refer to Figure 4) uses a fixed-
bed catalytic converter to oxidize the S02 in the gas stream to 803
which can be collected at about 78 percent H2S04.
The flue gas must be at about 850 F upon entering the con-
verter, so that reheat is necessary for retrofit installations.
Reheat is accomplished by the combustion of an auxiliary fuel, but
energy requirements are minimized by recovering the heat from the
treated flue gas in a regenerative heat exchanger. Because of leakage
across the heat exchanger, the S02 removal efficiency is less than the
total percentage conversion of S02 to 803. The 803 is scrubbed from
the flue gas with 1^804 in a packed bed absorbing tower and acid mist
is removed in a highly efficient fiber collector.
The flue gas must be relatively free of fly ash before
entering the converter in order to avoid fouling the catalyst. Pro-
vision is made for cleaning the catalyst on a vibrating screen, but
some of the catalyst is lost in each cleaning and the required fre-
quency of cleaning has not yet been established. The Wood River
installation was operated for only a few days before it became
apparent that the catalyst and mist eliminator had to be protected
against fouling while the reheat burners were being readjusted. A
revision of the reheat system is currently under way. The main
advantage of this process is simplicity; no operating labor or raw
materials are theoretically required and it is hoped no regeneration
step is necessary.
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18
CAT-OX
MIST
ELIMINATOR
FLUE GAS
FROM EXISTING
ID FAN
RECYCLE
*> STORAGE
FIGURE 4. CATALYTIC OXIDATION (RETROFIT CASE)
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19
The 78 percent sulfuric acid produced by The Monsanto Cat-Ox
process is more dilute than the 93-98 percent acid usually sold in
commerce, but it is suitable for many applications. Shipping costs per
unit of acid are higher, however. In addition, the acid may be discolored
by fly ash and may contain traces of dissolved metallic impurities from the
fly ash. It is not suitable for uses that require high purity, such as
battery acid, manufacture of detergents for food processing, and sulfonated
additives for lubricants. It can be used for fertilizer manufacture and
in pickling steel to remove scale, and these two uses represent the major
portions of the.acid market.
Estimated Costs
The range of estimated annualized costs among the four SO^
recovery processes discussed, varies from about 1.9* to 2.9 mills/kwh
for a 500-mw coal-fired plant. These costs include credit of 0.76 mill/
kwh for the sale of by-product acid at $20 per ton. Magnesia scrubbing
with acid production at a net cost of about 1.9 mills/kwh is the least
expensive of the four processes, and catalytic oxidation is the most
expensive. In general, acid production is about 0.3 mills/kwh less costly
on a net basis than sulfur production for a 500-mw power plant.
Obviously there may be many cases where Ohio utilities will not
be able to realize these prices for by-products. In fact, with regulations
forcing most utilities to take similar actions, the prices for sulfur and
sulfur-containing products are almost sure to decline in the future. The
first utilities that install such processes may enjoy a relatively attractive
market for a while, hut eventually many utilities may be forced to choose
the by-product with the least costly disposal (or "haul-away") penalty.
In the long run for many utilities, the production of elemental
sulfur may represent the least objectionable course of action. Sulfur is
relatively harmless from an environmental standpoint and its disposal by
selling even at depressed prices might obviate the costs of disposal of
sludges produced by other processes.
* Based on costs given by G. G. McGlamery, et al., "Conceptual Design
and Cost Study--Sulfur Oxide Removal from Power Plant Stack Gas--
Magnesia Scrubbing-Regeneration: Production of Concentrated Sulfuric
Acid". Table 56, p 93, TVA Bulletin Y-61. Report No. EPA-R2-73-244
to Office of Research and Monitoring, EPA, Washington, D.C., May 1973.
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20
U.S. MARKETS FOR SULFUR-CONTAINING COMPOUNDS
There are several sulfur-containing compounds which may be
produced from the sulfur oxides in utility flue gas. These include
sulfur, sulfuric acid, gypsum, ammonium 'sulfate, sodium sulfite, and
sulfur dioxide. The potential markets for each of these compounds
is discussed in the following sections.
Sulfur
Although sulfur is used for a variety of applications, the
manufacture of sulfuric acid is by far the largest use, amounting to nearly
90 percent of elemental sulfur consumed in the United States. Con-
sequently, markets for sulfur and sulfuric acid are closely related.
The nonacid uses for sulfur include the manufacture of chemicals and
the manufacture of refined grades of sulfur used in agriculture and
in the rubber industry.
Supply
During the past 5 years, the total U. S. production of sulfur
in all forms has fluctuated between 9.5 and 10.2 million long tons.* ,**
The high of 10.2 million long tons was reached in 1972. Total sulfur
production includes elemental sulfur produced at Frasch sulfur mines,
elemental sulfur recovered as by-product from petroleum refining and
natural gas operations, and hydrogen sulfide and liquid sulfur dioxide
recovery.
* U.S. Bureau of Mines, Mineral Industry Survey, Sulfur in 1972
(July 2, 1973).
** All quantities of elemental sulfur are given, according to custom, in
"long tons" of 2240 pounds. Quantities of other materials are given in
conventional "tons" of 2000 pounds, sometimes referred to as short tons
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21
Historically, most of the sulfur produced and consumed in the
United States has been obtained from Frasch sulfur mines. In 1970
Frasch sulfur accounted for 72 percent of domestic production of sulfur
in all forms (including by-product elemental sulfur, and the sulfur
values from by-product smelter acid, pyrites, and other sulfur containing
compounds). In 1972, the United States was an exporter of sulfur, and
Frasch sulfur accounted for only 59 percent of the apparent domestic
consumption.* All of the U.S. Frasch sulfur is produced in Texas and
Louisiana. The market share of Frasch sulfur has been declining with
corresponding gains in by-product sulfur recovered from natural gas,
from refinery operations, and from smelter gases. This trend is
expected to continue.
In the 10 year period between 1962 and 1972, the recovery of
elemental sulfur from natural gas and refinery gas streams increased from
0.9 to 1.9 million long tons per year. Increased recovery of elemental
sulfur at refineries is anticipated. This trend will be caused primarily
by ever increasing imports of high-sulfur Mideastern crude oil to U. S.
refineries, although the increasing demand for lower sulfur fuels caused
by environmental regulations will also contribute to the growth in re-
covered elemental sulfur. Increases in this recovered sulfur will be
concentrated in the refining centers primarily on the Gulf Coast and at
new refineries on the East Coast. This would not be expected to be a
major factor in Ohio or neighboring states.
Any new supplies of by-product sulfur or other sulfur compounds
originating from the electric utilities would have to compete directly
with recovered sulfur or by-product sulfuric acid from other industries.
Market penetration by the electric utilities would be expected primarily
at the expense of the Frasch producers of new sulfur.
In Ohio there is currently very little sulfur production. A
zinc smelter in Columbus produces about 60,000 tons of by-product acid,
* U.S. Bureau of Mines, Mineral Industry Survey, Sulfur in 1972
(July 2, 1973).
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22
or the equivalent of about 17,500 long tons sulfur per year. In
addition, Ohio refineries also recover some by-product sulfur. This
by-product sulfur is probably less than 30,000 long tons per year.
Supply Economics
The minimum sulfur price required to keep a Frasch mine in
operation is very difficult to estimate. Each mine is a unique situation.
Operating costs vary considerably. Mandersoh* has estimated the manu-
facturing costs at $7 per long ton for low-cost producers, $11 for a
medium-cost, and $15 for a high-cost producer. Rising fuel costs will
certainly inflate these estimates. If a 15 percent pretax return on
fixed investment is added, these estimates become $10, 15 and 23 per
long ton. Sales, general, and administrative expenses increase these
to minimum fob prices of $14, 19, and 27 per long ton.
The current posted price for crude, bright molten sulfur,
ex terminal Tampa, Florida, is $28 per long ton.** Large users
probably have contracts for considerably lower prices.
Ohio utilities are among the most distant potential sources
of sulfur from the large Florida and Louisiana markets. Therefore, if
sulfur from electric generation plants can force closing of Frasch
mines, Ohio utilities would have to compete with the most efficient
Frasch sulfur producers.
Assuming that Frasch mines would not be closed until revenues
failed to cover cash expenses, and assuming that Manderson's estimates
of manufacturing cost approximate cash expenses of producing Frasch
sulfur, Ohio utilities would have to offer sulfur at $11 per long ton
delivered in Louisiana. Shipping costs to Louisiana by barge on the
Ohio and Mississippi Rivers are estimated to be about $6-7 per ton, and
* Manderson, M. C., "The Sulfur Outlook", Sulfur & S02 Developments,
American Institute of Chemical Engineers, New York, 1971. He also
estimated 3.0 million long ton capacity for low cost, 5.8 million
for medium, and 2.8 million for high cost.
** Chemical Marketing Reporter, 204. 35 (July 30, 1973).
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23
using Manderson's estimate of $4 per long ton for sales and admin-
istrative expense, it appears that Ohio sulfur might be sold on the
Gulf Coast if essentially no netback were required to justify the
project.
Some industry observers believe that virtually all Frasch
mines would close if the price of sulfur were to fall below $15 per
Ion ton. At this level, utilities on the Ohio River might obtain a
small netback for sulfur.
Utilities not located on the Ohio River would be at a con-
siderable disadvantage, since transportation to the river and construction
of a trans-shipment terminal would be required. An alternative would be
rail shipment of molten sulfur from Ohio to Florida. This would cost an
estimated $13 to $15 per long ton, assuming commodity rates could be
negotiated. The existing class rates, however, are $29 to $31 per long
ton by rail.
Major Uses for Sulfur
Since most sulfur consumption in the United States is to
make sulfuric acid, sulfur and sulfuric acid would be the two products
in greatest demand which could be manufactured moot logically in large
volume by electric utilities.
There is already large production of sulfuric acid on the
Gulf Coast, but there are numerous utilities, which also burn high
sulfur coal, in states between Ohio and the Gulf Coast. Transportation
costs would be lower from these utilities to the Gulf Coast markets,
and therefore they would have a competitive advantage for shipments
in that direction. A rough estimate of the supply and demand for sulfur
in those states where the pollution control regulations are expected to
require stack gas desulfurization is summarized in Table 4. This analysis
indicates that if some sulfur were not recovered by those utilities nearer
to the market because they choose to use some other method of emission
control, there would then be a potential market for sulfur from Ohio utili-
ties. In order to penetrate this market, Ohio utilities would have to
deliver sulfur on the Gulf Coast at prices competitive with Frasch sulfur.
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TABLE 4. ESTIMATED SULFUR BALANCE IN SELECTED STATES, 1971
(Sulfur or Sulfur Equivalent units, 1000 long
tons; Sulfuric Acid units, 1000 short tons)
State
Ohio
Indiana
Illinois
W. Virginia
Kentucky
Tennessee
Miss. & Okla
Missouri
Arkansas
Alabama
Louisiana
Texas
Florida
Sulfur
Coal
Consumed
106 tons
38.2
23.0
28.1
16.3
20.3
14.7
0.5
11.8
-
16.1
-
-
5.1
Dioxide
Assumed
7. S
3
3
3
3
3
3
2.8
-
2.5
-
-
3
Emissions
, Sulfur
Equivalent,
1,010
630
770
440
550
400
300
-
360
-
-
140
Grouped States0
Total for States
Closer to Fla.
Than Ohio
3,590
By-Product
Sulfur
Recovered,"
c
c
c
c
c
770.4
3.8
378.0°
1152.2
Total
Production
477
-
960
1 1,713*
502
305
376
3,553
2,204
8,194
Sulfuric Acid Production
Estimated Acid
from
Smelter Gas
60
-
145
1,260
175
-
-
-
-
-
Net Sulfur
Consumption
119
-
227
126a
91
85
104
986
615
2,278
4,512
Potential
Sulfur
Excess
(Deficit)
891
630
543
l,264a
209
(85)
256
(986)
155
(2,134)
3 78 JO °
230
(a) Composite sulfuric acid production of W. Va., Ky., Tenn., Miss., and Okla.
(b) By-product sulfur equivalent from all sources directly competitive with potential recovery from S0£ emissions.
(c) Combined by-product sulfur from States of 111., Miss., Okla., Mo., Ark., and La.
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25
Non-Acid Uses for Sulfur
The non-acid uses for sulfur account for about 10 to 13 per-
cent of total consumption. The major industries using elemental sulfur
for non-acid purposes include the pulp and paper industry, carbon di-
sulfide, rubber, sugar, starch, malt, dye stuffs, and agricultural
chemicals. Of these uses, only the manufacture of carbon disulfide
and use of sulfur In the rubber Industry appear to be of significant
size as possible outlets for sulfur manufactured in Ohio.
Carbon Disulfide. Carbon disulfide accounts for approximately
3 percent of the sulfur consumption in the United States. Traditionally,
carbon disulfide was manufactured by the reaction of sulfur and charcoal.
With the possible exception of a small plant operated by Pennwalt in
Houston, Texas, all U.S. manufacturers use a newer process in which
methane and sulfur are catalytically reacted in the vapor phase. This
process produces carbon disulfide and hydrogen sulfide. The hydrogen
sulflde then is converted to sulfur for recycling.
Efforts to reduce sulfur emissions from carbon disulfide and
sulfur plants should result in recovery and utilization of virtually all
sulfur employed in the reaction. Therefore, one would expect sulfur
consumption to be very near the stoichiometric requirements of 0.842
pound sulfur per pound carbon disulfide. For the purposes of calculation,
sulfur consumption has been assumed to be 0.85 pound per pound carbon
disulfide. Historically, it is believed that this value has been closer
to 0.9 pound per pound, but this was before the strict enforcement of
pollution control regulations.
o
There are two major uses for carbon disulfide. The manufacture
of rayon and cellophane accounts for about 65 percent of all carbon
disulfide consumption. Manufacture of carbon tetrachloride accounts for
about 25 percent, and miscellaneous uses such as manufacture of rubber
chemicals accounts for the remaining 10 percent*. In the manufacture
of carbon tetrachloride from carbon disulfide, sulfur is regenerated and
net consumption is low.
* Oil Paint, & Drug Reporter, 202. 9 (July 24, 1972).
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26
There are 5 plants In the United States manufacturing" carbon
disulfide. The total capacity of these plants is 850 million pounds
per year. Two of these plants, with a capacity of 240 million pounds,
are located in West Virginia near the Ohio River. In 1972, the demand
for carbon disulfide was estimated at 775 million pounds,* or about
91 percent of total capacity. Assuming that the West Virginia plants
operated at the national average fraction of capacity, and assuming they
consumed 0.85 pound sulfur per pound carbon disulfide, then in 1972 they
would have consumed 186 million pounds or 83,000 long tons sulfur.
Actual demand for sulfur at these plants was probably much lower, since
one is associated with a carbon tetrachloride plant. The growth rate
for carbon disulfide is expected to be about 2 percent per year over the
next 5 years.
Rubber Processing. Although rubber processing accounts for a
small fraction of the total sulfur consumption in the United States, a
large fraction of the rubber products manufactured in the United States
are made in and near Ohio. In 1967 for example 26.7 percent of the
value of rubber goods shipped in the United States were manufactured
in Ohio, and 41 percent of the national total were made in the East
North Central census region.**
The quantities of sulfur required in any particular rubber
recipe will vary depending upon the type of rubber to be vulcanized and
the desired properties of the finished product. In general, the soft
rubber products contain less than 3 parts sulfur per hundred parts rubber,
while hard rubber products may obtain up to 60 parts per hundred. Less
sulfur is consumed in vulcanizing synthetic rubbers than in vulcanizing
natural rubbers to obtain the same properties. Thus as natural rubber
diminishes in importance compared with synthetic rubber, the overall
* Oil Paint, & Drug Reporter, 202. 9 )July 24, 1972).
** U.S. Department of Commerce, 1967 Census of Manufacturers, p 30A-9.
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27
consumption of sulfur pet pound of rubber will decrease. Furthermore,
the use of other chemicals as accelerators in the vulcanizing process
decreases the amount of sulfur required.
There is a variety of opinion on the average amount of sulfur
consumed per pound of rubber. The opinions vary from 3 to 4 parts per
hundred for natural rubber and 1.5 to 3 parts per hundred for synthetics.
For the purposes of estimating, about 3 parts per hundred was assumed to
be the average for all rubber. Based on this assumption, and on estimated
1973 consumption of rubber*, the current estimated consumption of sulfur
for rubber vulcanizing in Ohio is about 24,400 long tons of sulfur per
year.
Although elemental sulfur can be used without special pro-
cessing for most applications, special grades of sulfur are required
for use in rubber vulcanization. These special grades may be ground or
triturated to reduce particle size or some times sublimed and extracted
with carbon disulfide to make insoluble sulfur.**
The special grades of sulfur used by the rubber industry are
sold by a number of chemical companies. The major suppliers of rubber
grade sulfur are C. P. Hall,' Harwich Chemical, Monsanto, FMC (Niagara
Chemical Division), H. M. Royal, Smith Chemical, and Stauffer.
Minor Uses. The pulp and paper industry consumes some elemental
sulfur for the preparation of sulfide chemicals used in the pulping oper-
ation. This application is discussed in the following section on sodium
sulfite.
Elemental sulfur is used in the manufacture of a variety of dyes
and chemicals. These markets are small and diverse when compared with
other market segments discussed in this report.
Sulfur is used to generate sulfur dioxide which finds appli-
cation in bleaching malt and beet sugar juice, and in the production
of cornstarch.
* Rubber Age, p 29 (January 1973).
** For more details see Varnat, P. "Refined Sulfur and Special Grades",
Sulfur, p 65 (May/June 1967).
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28
The traditional agricultural use for sulfur has been in the
manufacture of fungicides and insecticides. These applications require
specially processed sulfur and have been declining in their significance.
Although the use in the manufacture of insecticides has been declining,
there may be a slight increase in agricultural use of sulfur for the
manufacture of sulfur-coated urea. A process for the manufacture of
sulfur-coated urea for use as fertilizer has been developed by the
Tennessee Valley Authority and there has been some commercial interest
in this fertilizer. It is anticipated, however, that this sulfur will
be consumed on the Gulf Coast near urea manufacturing facilities.
Furthermore, it is anticipated that it will remain a specialty fert-
ilizer for use on turf and pastures rather than gain widespread
application.
Summary of Sulfur Markets
Nearby markets for elemental sulfur in Ohio are limited. It
appears that there is now a market for about 110,000 long tons in Ohio
at sulfuric acid plants. In addition, the DuPont plant in Wurtland,
Kentucky (about 15 miles upstream from Portsmouth, Ohio) consumes an
estimated 30,000 long tons. If rubber grade sulfur for use in Ohio were
manufactured from Ohio by-product sulfur, this would add about 24,000
long tons, and Ohio utilities might supply up to 40,000 long tons for
nonacid chemical uses. Thus the maximum nearby market for by-product
sulfur from Ohio would be about 200,000 long tons per year in 1975.
It will be difficult to penetrate rubber and chemical markets
for sulfur. Furthermore, the installation of a new smelter near
Louisville, Kentucky will reduce the consumption of elemental sulfur
for sulfuric acid manufacture in the Ohio River valley. Therefore, a
more realistic estimate of nearby available markets for elemental sul-
fur produced at Ohio utilities would be 120,000 long tons per year.
This would be diminished by any by-product sulfuric acid from Ohio
utilities. If sulfur from Ohio utilities can be delivered in Florida
and Louisiana at costs competitive with Frasch producers, these markets
can absorb essentially all sulfur removed from Ohio utility flue gas.
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29
Sulfuric Acid
Supply and Demand in the North
Central States
Although there has been little growth in the production of
new sulfuric acid* in the period from 1966 to 1971, there has been a
shift in the geographical location of the acid production away from
the northern states towards the Gulf Coast. During the period from 1966
through 1971 the production of new acid in the North Central states
o
declined from 4.5 million tons to 3.4 million tons. During the same
period, production of the new acid in Florida and Louisiana increased
from 8.8 million tons to 11.7 million tons.
In 1971, Florida consumed an estimated 2,278,000 long tons
of elemental sulfur for acid manufacture and Louisiana consumed 986,000
long tons. Additional acid capacity is under construction in these
states.
This shift in the location of the sulfuric acid production
is, for the most part, caused by changes in the phosphate fertilizer
industry, as discussed later.
xv:«-
Supply and Demand in Ohio
Because of the relatively high transportation costs for overland
shipments of sulfuclc acid, new sulfuric acid generally is consumed near
the production site. By-product sulfuric acid can be shipped over longer
distances and may be consumed several hundred miles from its point of
origin. By-product sulfuric acid from electric utilities in Ohio would
not be expected to displace by-product sulfuric acid generated from
other sources. Therefore, for practical purposes, the available market
for by-product sulfuric acid from utilities would be limited to the
* New acid includes all acid manufactured directly in sulfuric acid
plants, including acid from smelter gas and acid sludge. Some
spent sulfuric acid recovered from chemical processes (e.g., drying
nitric acid) is sold for certain applications. This used acid is
excluded from new acid statistics.
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30
markets normally served by sulfuric acid manufactured In or near Ohio
from elemental sulfur. It is reasonable to use the production of sul-
furic acid from elemental sulfur as a good estimate of the Ohio demand
for acid.
The reported production of sulfuric acid in Ohio has varied
from a high of 704,000 tons in 1965 to a reported low of 477,000 tons
in 1971 (See Table 5). It is believed that the 1971 figure may have
omitted production from one sulfuric acid plant. In 1972, Ohio pro-
duction of sulfuric acid was 560,000 tons.* Of this, American Smelting
and Refining Company makes about 60,000 tons acid per year from smelter
gas. In addition, an estimated 115,000 tons is made by, burning sludge
which is recycled from petroleum refineries. This leaves about 385,000
tons sulfuric acid produced from elemental sulfur in Ohio. The Ohio
production of sulfuric acid would consume approximately 112,000 long
tons sulfur. As estimated 1,090,000 long tons of sulfur were emitted
to the atmosphere in 1971 by Ohio utilities.
Central Ohio. The only acid capacity in Central Ohio is that based
on smelter gas. This smelter, located in Columbus, has an annual capacity
of 64,000 tons acid. It serves central Ohio markets as well as shipping
to more distant points within the state. As would be expected, the remaining
sulfuric acid plants in Ohio are located in the industrialized areas which are
generally near the borders (See Table 6).
Northern Ohio. The installed sulfuric acid capacity in northern
Ohio is slightly over 600,000 tons per year, including the estimated 115,000
tons per year manufactured from acid sludge. It appears that the sulfuric
acid plants in Ohio which burn elemental sulfur have been operating at near
50 percent capacity. Therefore, it is estimated that approximately 240,000
tons sulfuric acid are manufactured in northern Ohio from elemental sulfur.
Some of this elemental sulfur may be by-products from Ohio refineries. The
actual market for sulfuric acid in northern Ohio may be somewhat larger,
since by-product sulfuric acid from Canadian smelters has reportedly been
imported into Cleveland. These Canadian imports are believed to be small,
however.
* U.S. Bureau of Census, unpublished data.
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31
TABLE 5. PRODUCTION OF SULFURIC ACID IN OHIO
1,000 tons new 100% H SO,
Year
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
New Production
661.5
659.1
674.8
704.0
689.0
652.6
628.4
579.7
641.6
477,0
560.3
(a)
Shipments
512.1
486.4
521.8
535.1
554.7
520.3
519.9
500.4
431.7
378.4(b)
Number of
Establishments
14
12
12
11
11
10
9
8
7(b)
Source: U.S. Department of Commerce, Current Industrial Reports M28A,
Sulfuric Acid.
(1972 from unpublished Bureau of Census data)
(a) Includes interplant transfers.
(b) May not include production from Coulton Chemical Company.
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32
TABLE 6. OHIO SULFURIC ACID PLANTS
Company/Location
Capacity
(1000 tons/yr,
100% basis)
Raw Materials
Allied Chemical Corp.
Cleveland 130
American Cyanamid
Hamilton 90
American Smelting &
Refining Co.
Columbus 64
Coulton Chemical Co.
Toledo 174
Agrico Chemical Co.
(Subsidiary Williams Co.).
Cairo (near Lima) 43.5
DuPont
Cleveland 215
North Bend (near
Cincinnati) 175
Minnesota Mining & Manu-
facturing Co.
Copley 60
Total 951.5
elemental sulfur
smelter gas
acid sludge, H_S
and elemental
elemental sulfur
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33
Not all sulfur-burning capacity can be eliminated. Because
there is no flexibility in production of by-product sulfuric acid, sulfuric
acid manufactured from sulfur must be available to compensate for fluctuations
in supply and demand. Therefore, it appears that approximately 200,000 tons
by-product sulfuric acid could be sold from a northern Ohio utility site
each year.
Southern Ohio. The only two sulfuric acid plants located in
Southern Ohio are the American Cyanamid Plant in Hamilton and the DuPont
plant near Cincinnati. There are, however, several sulfuric acid plants in
neighboring states located in the Ohio Valley which would compete in the
same markets as a sulfuric acid plant in southern Ohio. (See Table 7.)
Due to the lower costs of barge shipments compared with overland
shipments, it is feasible to ship sulfuric acid along the river to fairly
distant large customers. To serve smaller customers or customers inland
from the river, a transhipment terminal is required and the distribution costs
are increased considerably. .Because of the relatively low cost of barge
transportation compared with overland transportation, these sulfuric acid
plants along the river are in competition. In order to compete effectively
in southern Ohio and in the Ohio River Valley, a sulfuric acid plant manu-
facturing sulfuric acid by-product from utility operations would have to be
located on the Ohio River.
The installed sulfuric acid capacity on the Ohio River and its
tributaries between Newell, Pennsylvania and Calvert City, Kentucky is
1,165,000 tons per year. The sulfuric acid production and consumption in
the Ohio River Valley and its tributaries is estimated to be about 700,000
tons per year.
Upstream from Ohio, St. Joe Minerals produces about 300,000 tons
sulfuric acid annually from smelter gas at Monaca, Pennsylvania. This will
be increased to 350,000 tons in the late 1970's. In addition, U.S.S.
Chemicals may be manufacturing up to 50,000 tons sulfuric acid from hydrogen
sulfide and sulfur recovered from coke oven gases at Pittsburgh.
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TABLE 7. SULFURIC ACID PLANTS IN NEIGHBORING STATES
Company/Location
Annual Capacity. 1,000 tons
On Ohio River
and Tributaries Other Raw Materials
Allied Chemical Corp.
Buffalo, N.Y.
Detroit, Mich.
Newell, Pa.
Nitro, W. Va.
-
-
250
140
195
200
-
-
sulfur, sludge, RJS
sulfur, sludge
sludge, pyrites
sulfur
Detroit Chemical Works
Detroit, Mich.
DuPont
Wurtland, Ky.
International Minerals &
Chemicals
Indianapolis, Ind.
Pennwalt Corp.
Calvert City, Ky.
St. Joe Minerals Corp.
Monaca, Pa.
U.S.S. Chemicals
Pittsburgh, Pa.
Williams Co.-Agrico Division
Bay City, Michigan
Witco Chemical Corp.
Petrolia, Pa.
200
50
300
50
35 sulfur
sulfur, sludge
65 sulfur
sulfur
smelter gas
sulfur, hydrogen
sulfide
40 sulfur
45 sludge
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35
Downstream from Ohio, American Smelting and Refining Company is
planning to build a zinc smelter in Breckinridge County, Kentucky. This site
is on the river between Louisville and Owensboro. This project is still in
the planning stages, but the plant is expected to be cmstream in mid or late
1976. About 360,000 tons by-product acid will be produced at this smelter.
Some of the acid from this new smelter will no doubt be sold inland and some
will be moved down river, possibly to be sold along the Mississippi as well
as along the Ohio. It must be anticipated, however, that some of the by-
product acid from the new smelter will be sold up river.
Finally, some sulfuric acid capacity from elemental sulfur will be
required to meet fluctuations between the supply of by-product acid and the
demand. A temporary oversupply of by-product acid could cause monumental
storage logistics and disposal problems.
When all these factors are considered, it appears that thefe may
be a market for between 100,000 and 150,000 tons by-product sulfuric acid
from utilities located along the Ohio River.
Demand According to End Use
Sulfuric acid is one of the most versatile chemicals manufactured
in the United States. Traditionally it has been the least expensive acid
available. Further reduction in the price of sulfuric acid would not,
therefore, be expected to increase the potential market. There is one
exception to this price inelasticity, however, and that is in the use of
sulfuric acid for a leaching low-grade copper oxide ores. The avail-
ability of by-product sulfuric acid from Western copper smelting operations
has made the recovery of copper from low-grade copper oxide ores feasible.
The major end uses for sulfuric acid are summarized ^n Table 8
which shows that, over half the sulfuric acid used in the United States is
consumed in the manufacture of phosphate fertilizers. The remaining
sulfuric acid is used for a wide variety of applications. Some of the
more important applications are discussed below.
Fertilizer. The trend in the phosphate fertilizer industry has
been to build large efficient plants to manufacture phosphate fertilizers
on the Gulf Coast. Most of these plants are located in Florida and
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36
TABLE 8. SULFURIC ACID END-USE PATTERN, 1970
Tl> on sand
tons
(I00%husis)
Fertilizer
Phosphoric acid products 13,750
Normal superphosphate 1,240
Cellulosics
Rayon 520
Cellophane 170
Pulp and paper 600
Petroleum alkylation 2,400
Iron and steel pickling 800
Nonfcrrous metallurgy
Uranium ore processing 300
Copper leaching 350
Chemicals
Ammonium sulfate-coke oven 500
synthetic 480
chemical byproduct 190
Chlorine drying 150
Alum 600
Caprolactam 260
Dyes and intermediates 370
Detergents, synthetic 400
Chrome chemicals ' 100
HCI 150
HF 880
TiOj 1,440
Alcohols 1,800
Other chemicals 380
Industrial water treatment 200
Storage batteries 140
Other processing 470
Total 28,640
Source: McGlamery, G.G., et al, "Sulfur Oxide Removal
from Power Plant Stack Gas - Magnesia Scrubbing",
TVA Bulletin Y-61, p 101 (May, 1973).
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37
Louisiana. Consequently, these two states are the two largest producers
of sulfuric acid. These Gulf Coast fertilizer plants manufacture concentrated
fertilizers like triple superphosphate and diammonium phosphate, both of
which require manufacture of intermediate phosphoric acid. Not only are
economies of scale realized by the construction of large plants, but shipping
costs are minimized because the concentrated fertilizers produced in these
plants contain more phosphate than does the phosphate rock from which they
are manufactured.
In contrast, there is some manufacture of normal superphosphate
in Ohio. Normal superphosphate is a low analysis fertilizer containing less
phosphorus per ton than the phosphate rock. Therefore, normal super-
phosphate is generally manufactured near the farmer. The trend has been
to retire these northern superphosphate plants and to replace them with the
large concentrated phosphate fertilizer plants on the Gulf Coast.
There are mixed opinions whether this trend to close the normal
superphosphate fertilizer plants in the North and expand production on the
Gulf Coast will continue. Some industry observers expect the trend to
continue until the northern fertilizer plants are all abandoned. This
conclusion would certainly result if northern states were to require these
fertilizer manufacturers to install equipment to control fluoride emissions
to the air. Such emissions can be economically controlled only in large
modern plants. Even without the imposition of fluoride emission controls on
these modern plants, the economics of the fertilizer industry would indicate
that at current transportation and sulfuric acid prices, the normal super-
phosphate plants will be gradually retired. It is now more economic to make
a concentrated fertilizer near the source of phosphate rock and ship it to
the farm areas than to ship the rock and make a less concentrated fertilizer
near the farmer. Finally, farmers and bulk fertilizer blenders have become
accustomed to the convenience and economies obtained by use of higher
analysis fertilizers. It would be difficult to reverse the trend
toward use of higher analysis fertilizers.
The opposing view states that the closure of normal superphosphate
plants has ceased, that the inefficient plants have been already shutdown,
and that the northern fertilizer industry may even grow as a result of low
cost sulfuric acid obtained as by-product from electric utilities. It does
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38
appear that If an Ohio fertilizer manufacturer could obtain sulfuric acid
at essentially no cost, then normal superphosphate could be manufactured for
a lower cost per unit of phosphorus than a more concentrated fertilizer
could be delivered from the Gulf Coast. When the cost of distributing
fertilizer to the retailer and delivering to the farmer are considered,
however, the costs per unit of nutrient are very close.
As sulfur dioxide is removed from utility flue gas, the soils
in the North Central states may become sulfur deficient. There is already
a small region of sulfur-deficient soils in southwestern Indiana, and
there are very limited areas of coarse textured soils, which are the most
likely to become sulfur deficient, near the northern edge of Ohio.* Normal
superphosphate does have the advantage of containing sulfur as well as
phosphorus, whereas the more concentrated phosphate fertilizers do not.
Of course, there are other chemicals like ammonium sulfate, sulfur, and gypsum
which can be used to supply necessary sulfur to the soil.
Although a detailed analysis of each specific situation is required
to determine the fate of a particular venture, it seems probable that the
economic advantage in a free market of normal superphosphate compared with
higher analysis fertilizers will be at best marginal, and that easier
handling of the higher analysis materials will perpetuate the decline in the
manufacture of normal superphosphate in the northern states.
One possibility for a power plant located along the Ohio River
would be the manufacture of sulfuric acid, to be used on-site for the manufacture
of phosphoric acid and concentrated phosphate fertilizers. A very preliminary
analysis indicates that phosphoric acid and diammonium phosphate fertilizer
could be manufactured on the Ohio River for about the same price as it can be
manufactured and shipped from the Gulf Coast, assuming that the sulfuric acid
would be available at no cost in Ohio and the sulfur would cost about $18
per long ton on the Gulf Coast. The minimum economic size of a phosphoric
acid plant would probably have a capacity of about 700 tons PoO,. per day,
or 230,000 tons per year. By coincidence, this happens to be the 1972
consumption of phosphate fertilizers in Ohio.** This capacity would correspond
to about 438,000 tons sulfur dioxide removed from utility flue gas.
* Beaton, J.D., S.L. Tisdale, and J. Platou, "Crop Responses to Sulfur In
North America", Technical Bulletin 18, The Sulfur Institute, Washington, D.C,
** Hargett N.L., 1972 Fertilizer Summary Data. National Fertilizer Develop-
ment Center, Tennessee Valley Authority, Muscle Shoals, Alabama.
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39
A utility would have to work closely with a fertilizer manu-
facturer in developing a venture to manufacture concentrated phosphate
fertilizers in Ohio. Furthermore, the utility and the fertilizer oper-
ation would probably have to be located on the Ohio River in order to
obtain the low transportation rates needed to make such a project viable.
Although no single Ohio utility plant located on the Ohio
River emits over 400 tons per day of sulfur dioxide, there are locations
where two large power plants, which together emit about the quantity of
sulfur dioxide needed for such a venture, are Located in close proximity.
The Cincinnati and Steubenville areas appear to be likely locations for
such a venture.
These areas are not mentioned to demonstrate that such a
venture would, in fact, be practical. An intensive and detailed study
would be required before such a conclusion could be drawn. However, such
a venture would probably not be practical for any other groups of Ohio
utilities. In evaluating such a venture, the potential water pollution
problems associated with fertilizer manufacture would also have to be
considered. The manufacture of phosphoric acid generates large quantities
of gypsum, and a very large gypsum pond area containing acidic water
would be required.
Petroleum Refining. Petroleum alkylation ranks second to
fertilizers as the largest consumer of sulfuric acid, yet petroleum
alkylation accounts for only about 8 percent of consumption. Sulfuric
acid is used by Standard Oil and Sun Oil Company in their Toledo
refineries for alkylation. An estimated 100,000 tons sulfuric acid are
consumed each year in Ohio in petroleum operations. Nevertheless, the sulfur
values from the sulfuric acid used in petroleum refining are recovered in
the form of acid sludge which is returned to sulfuric acid plants to be
burned and reprocessed into new sulfuric acid. Therefore, this portion of
the apparent end-use market is not available for penetration by sulfuric acid
from utilities or other sources.
In addition to the acid sludge from Ohio refineries, an estimated
15,000 tons acid per year are believed to be reprocessed in an Ohio sulfuric
acid plant for a Michigan refinery. Thus an estimated 115,000 tons per year
sulfuric acid are made in Ohio from acid sludge.
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40
Titanium Dioxide. The third largest consumer of sulfuric acid
is the manufacture of titanium dioxide by the sulfate process which uses
4 to 4.5 tons of 100 percent sulfuric acid per ton of titanium dioxide.
Although there are two titanium dioxide plants in Ashtabula, Ohio, both
use the competing chloride process. The chloride process does not require
sulfuric acid. All of the plants using the sulfate process are located
on the East Coast except a plant of NL Industries in St. Louis, Missouri,
with a rated capacity of 108,000 tons Ti(>2 per year. Its acid is supplied
from a captive acid plant burning sulfur to S02> with an annual capacity
of 350,000 tons.* None of these plants is considered close enough to
Ohio utilities to provide markets for by-product sulfuric acid generated
in Ohio.
Steel Pickling. During the hot rolling of steel, an oxide
scale forms on the surface. Before further finishing, such as cold
rolling, this scale must be removed. Prior to 1966, sulfuric acid
was the principle means for descaling of hot rolled steel. Since then
the hydrochloric acid descaling process has displaced much of the sul-
furic acid formerly used in descaling steel. Hydrochloric acid offers
a number of advantages over sulfuric acid for continuous pickling of
steel. These include:
(1) Better quality steel
(2) Lower cost operation
(3) Ability to regenerate acid.
The cost savings from use of hydrochloric rather than sulfuric
acid result from increased speed of the pickling operation. Line speed
increases of 25 to 50 percent are claimed for most pickling lines using
hydrochloric rather than sulfuric acid.
Disposal of waste pickle liquor presents a potential water
pollution problem. Technology is available to regenerate hydrochloric
acid from spent pickle liquor.** Recovery of sulfuric acid from spent
* Stanford Research Institute, Directory of Chemical Producers,
1973, p 857
** For instance, the Woodall-Duckham Process, licensed by Pennsylvania Engineering
Corporation, Pittsburgh, Pennsylvania.
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41
pickle liquor is considerably more difficult, and according to the best
information available, has not been adequately proven in commercial
practice in the United States.
Although the use of sulfuric acid for steel pickling has
declined in recent years, industry observers believe it has now
stabilized. Pickling is an important use of sulfuric acid in Ohio
and the neighboring area. No regional data were easily available,
but it is estimated that somewhat less than 100,000 tons were used
in this area of the 800,000 tons listed as the U.S. pickling acid
consumption in Table 8. .
Hydrofluoric Acid. In the United States an estimated
920,000 tons sulfuric acid was consumed in 1973 for the manufacture of hydro-
fluoric acid. Demand has been projected to grow at an annual rate of
6.5 percent per year through 1977.* There is only one hydrofluoric acid
plant in Ohio. It is owned by Harshaw Chemical Company in Cleveland and
has an annual capacity of 18,000 tons (which would consume about 44,000 tons
sulfuric acid). The industry has been running near capacity. In addition,
there is a plant with an annual capacity of 20,000 tons in Nitro, West
Virginia and another in Calvert City, Kentucky with a capacity of 25,000 tons.
Both of these are located adjacent to captive sulfuric acid plants. It
would probably be very difficult to sell by-product acid from Ohio utilities
at these locations, although there might be an opportunity to dispose
of surplus acid for little more than shipping and administrative costs.
Feasible Market Area for Ohio Utilities
Gulf Coast Markets. There are several factors which will tend
to limit the ability of Ohio utilities to penetrate distant sulfuric acid
markets, especially the large markets on the Gulf Coast. The first and
most obvious limitation to penetration of Gulf Coast markets would be in
Chemical Marketing Reporter, 203. 9 (February 5, 1973).
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42
the transportation cost. Sulfuric acid weights about 3 times as much as
the sulfur contained in the product. Therefore, acid transportation
costs will be much higher than sulfur transportation costs. Barge
transportation of acid to the Gulf Coast is estimated to be about $6
to $7 per ton.
As the cost of sulfur on the Gulf Coast is reduced, the manufactur-
ing cost for sulfuric acid approaches the shipping cost from Ohio. At $15
per long ton for sulfur, the manufacturing cost for sulfuric acid in a modern
efficient plant would be about $6.40 per ton (excluding return on capital).
Even with sulfur at $25 per long ton, sulfuric acid could be manufactured
at a cost of about $9.30 per ton.
A second factor which will limit the long-distance shipments of
sulfuric acid manufactured at utilities would be the required storage
capacity. Sulfuric acid is more expensive to store than sulfur. Electric
utilities operate more or less continuously, and acid would be produced
throughout the year. Seasonal variations in the demand for electricity
would result in corresponding variations in the production of acid. Such
variations would probably not correspond to the customer's demand for acid.
Storage capacity would be required to take care of these imbalances.
Furthermore, additional storage capacity would be required as a contingency
for unexpected interruptions in the transportation system.
A third factor which will limit the ability of Ohio utilities to
ship sulfuric acid or magnesium sulfite to Gulf Coast markets relates to the
energy crisis. The Gulf Coast manufacturers of sulfuric acid have integrated
the sulfuric acid manufacture with fertilizer-manufacturing operations. The
heat released by burning sulfur to make sulfuric acid is converted to steam
which is then used in the fertilizer manufacture. For every ton of sulfuric
acid manufactured, about 1.1 tons steam is produced. To replace this steam,
fuel containing about 2.64 million Btu per ton acid would be required.
Because of the gas shortage, a Gulf Coast fertilizer manufacturer would
probably have to rely upon No. 2 fuel oil to replace this process steam.
This fuel oil currently sells for about $0.15 per gallon or $1.08 per
* Bixby, D.W., D.L. Rucker, and S.L. Tisdale, Phosphatic Fertilizers, The
Sulphur Institute, Technical Bulletin 8, Washington, D.C. (1966).
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43
million Btu. Thus the increased fuel cost from purchasing acid rather
than manufacturing it on site would be $2.85 per ton acid. In addition,
significant plant modifications would probably be required in order to
burn fuel oil rather than obtain this heat from burning sulfur. Therefore,
the by-product sulfuric acid from utilities would probably have a
penalty of at least $3.00 per ton. However, the difficulty in obtaining
fuel on the Gulf Coast, as well as other parts of the country, might
override current economic considerations. All factors considered, it
appears that at present it is not economically attractive to ship sulfuric
acid from Ohio to the Gulf Coast.
Nearby markets. If it is economically feasible for Ohio utilities
to recover sulfur from flue gas in the form of sulfuric acid, then it will
also be feasible for utilities in neighboring states where high-sulfur coal
is also burned to generate electricity. Since more sulfur is emitted to the
atmosphere in Ohio and neighboring states than is consumed in these states
in the form of sulfuric acid, the markets available to Ohio utilities for
marketing sulfuric acid in nearby states may be limited. If it were not
for this potential competition from other manufacturers of by-product
sulfuric acid, it would probably be feasible to ship by-product acid over
longer distances to penetrate markets in neighboring states. The actions
of the utilities in surrounding states, as well as the variations in the
regulations in such states, will determine to what degree the market
outside of the State of Ohio can be penetrated.
Transportation costs for distances up to 200 miles are fairly low
(See Figure 5) and should not limit nearby marketing efforts. Some
smelters such as Copper Hill in Tennessee currently ship and market a
portion of their by-product acid production 400 miles or more in jumbo
tank cars, but they have not yet encountered competition from other
by-product acid producers nearer to the market.
Summary of Sulfuric Acid Markets
There may be an opportunity for by-product sulfuric
acid to displace some of the estimated 240,000 tons sulfuric acid now manu-
factured in northern Ohio. Some production from elemental sulfur will have
to be retained to provide flexibility in the operations. Thus, the
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44
I2r-
10
8
o
o
O_
o.
I
CO
RANGE OF
BARGE COSTS
O
I
_L
I
100 200 300 400
DISTANCE, MILES
FIGURE 5 . SULFURIC ACID SHIPPING COST
500
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45
estimated potential market for by-product sulfuric acid from utilities in
northern Ohio is about 150,000 tons per year. In southern Ohio, a
utility located on the Ohio River could probably sell between 100,000 and
150,000 tons per year. It is not believed economically attractive to
ship sulfuric acid to the Gulf Coast markets from Ohio.
Gypsum
Applications and Demand
By far the largest use of gypsum in the United States is in the
manufacture of gypsum board and plaster. For these applications, the gypsum
is calcined and a fine product is preferred. A typical calcined product
for wallboard manufacture would have at least 85 percent smaller than 100
mesh. These calcined products represent over 70 percent of the total
gypsum consumption.
The second major use for gypsum is as a portland cement retarder.
This application typically consumes between 18 and 22 percent of the total
gypsum used in the United States. The materials handling equipment used
by the cement industry is designed to handle crushed gypsum in the size range
between one quarter and 2 inches, with an average size between one-half and
three quarter inch. In order to be used as a cement retarder, by-product
gypsum would have to be pelletized to achieve the proper size.
The third major application for gypsum is agricultural. Gypsum
is used as a source of sulfur in sulfur deficient soils. Agricultural gypsum
accounts for 7 to 8 percent of the national consumption, but most of this
consumption is in California and, to a lesser extent, in the Southeastern
United States.
As can be seen in Table 9, agricultural gypsum sales in the East
North Central Region of the United States (as reported by the Bureau of
Mines) are very small. U.S. Department of Agriculture reports even lower
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46
TABLE 9. 1972 SALES OF GYPSUM AND GYPSUM PRODUCTS--
EAST NORTH CENTRAL CENSUS REGION
Tons
Uncalcined
Portland cement retarder 557,845
Agricultural 10,717
Other 24,280
Total Uncalcined 592,842
Calcined
Building plasters 163,345
Industrial plasters 87,262
Board products 2,195,527
Total Calcined . 2,446,134
Total Gypsum and Gypsum Products 3,038,976
Source: U.S. Bureau of Mines, Gypsum in the Fourth Quarter 1972,
Mineral Industry Survey (March 5, 1973).
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47
agricultural consumption of gypsum for the region. Consumption of agricultural
gypsum in Ohio has declined from 78 tons in fiscal 1969 to zero in fiscal
*
1972. Unless soils in Ohio become sulfur deficient, agricultural use of
gypsum in Ohio will remain insignificant.
In the East North Central region, about 80 percent of the gypsum
consumed is calcined to make gypsum board and plaster products. Miscellaneous
uses of gypsum account for only 1 percent of the total consumption.
Market Growth
Historically, there has been little growth in gypsum products
during the past decade (see Table 10). Total U.S. consumption has generally
remained between 15 and 17 million tons per year. In 1972, however,
consumption spurted to 20 million tons. This increase in consumption accompanied
a significant increase in construction activity. Many economists are expecting
a decline in housing starts in 1973 and 1974. The long term growth in housing
**
starts between 1972 and 1980 has been projected to be about 1 percent per year.
It is of interest to note that much of the increased production
of crude gypsum in 1972 came from domestic mines. This indicates considerable
flexibility and unused capacity. In addition, the wallboard plants were
able to increase production significantly without any increase in capacity.
There have been no new wallboard plants constructed during recent years,
although at some locations the equipment speed has been increased. At many
wallboard plants, extensive overtime was used during 1972 to meet the increase
in demand.
Ohio Markets
There are two gypsum mines located in Ohio. Both of these are
in Ottawa County. One is a pit mine operated by Cellotex, while the other
is an underground mine operated by U.S. Gypsum. Production figures on
* U.S. Department of Agriculture, "Commercial Fertilizers Consumption in
the United States", for fiscal years 1970, 1971, 1972, Table 5.
**U.S. Department of Commerce, "U.S. Industrial Outlook 1973", p 3,
U.S. Government Printing Office, Washington, D.C.
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TABLE 10. U.S. AND OHIO GYPSUM STATISTICS (Thousands Short Tons)
1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972
oi av.
Crude gypsum mined 9,804 9,969 10,388 10,684 10,033 9,647 9,393 10,018 9,905 9,436 10,418 12,367
Crude gypsum imported
for consumption 4,956 5,421 5,490 6,258 5,911 5,479 4,569 5,474 5,858 6,128 6,094 7,718
Total crude gypsum,
mined & imported — 15,390 15,878 16,942 15,944 15,126 13,962 15,492 15,763 15,564 16,512 20,085
Gypsum calcined 8,406 8,819 9,181 9,440 9,320 8,434 7,879 8,844 9,324 8,449 9,526 11,984
Gypsum calcined
in Ohio — - — — « — 334 359 356 321 358
Sources: Bureau of Mines, Minerals Yearbook, Gypsum
Bureau of Mines, Minerals Industry Survey, Gypsum in the Fourth Quarter 1972
(March 5, 1973).
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49
these mines are not available. Both companies operate nearby calcining
plants, however, and it is believed that production at the mines approxi-
mates the calcining requirements.
There are three calcining plants currently operating in Ohio.
These are the U.S. Gypsum plant at Gypsum, the Cellotex plant at Port Clinton,
and the National Gypsum plant at Lorain. It is believed that the gypsum
calcined at the first two locations is from local captive mines. The
National Gypsum plant is probably supplied from mines in Michigan. More
gypsum is mined in Michigan than in any other state. In 1971 the total
production of calcined gypsum in Ohio was 358,000 tons, up from 321,000 tons
in 1970 but about the same as the 356,000 tons calcined in 1969. A typical
gypsum wallboard plant consumes 200,000 to 300,000 tons gypsum per year.
This would indicate that the Ohio plants are smaller than the industry
average. Any increase in capacity in the State of Ohio would probably be
expansions at existing plants.
Marketing Considerations
There is virtually no merchant market in gypsum. Gypsum is mined,
calcined, and sold by integrated companies. Even imported gypsum is usually
from captive mines. In order to interest the major gypsum companies in by-
product gypsum, it would probably have to be priced at $2.00 to $2.50 per ton
in those parts of the country, like Iowa and Texas, where there are large
seams of high-quality gypsum. The gypsum mined in Ohio is of lower quality,
and some beneficiation is needed before processing. In Ohio, it might be
possible to obtain as much as $3.00 per ton, delivered to the calcining
plant. It would be unrealistic for utilities to expect to obtain the current
gypsum price. The 1971 national average price for crude gypsum was $3.72 per
*
ton.
* U.S. Bureau of Mines, Minerals Yearbook, 1971 Preprint, Gypsum chapter.
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50
Before by-product gypsum from flue-gas desulfurization units could
be sold to a manufacturer of gypsum products, it would be necessary to
determine whether such gypsum were in fact suitable for manufacture of
wallboard. Although by-product gypsum is being used to manufacture wallboard
in Japan, Japanese conditions are somewhat different. U.S. wallboard manu-
facturers suspect Japanese specifications for wallboard are less demanding
than those in the United States.
National Gypsum has made a preliminary evaluation of by-product
gypsum from the Chiyoda Thoroughbred 101 flue gas desulfurization process.
The preliminary results were encouraging, but evaluation of larger samples
is required. The sample tested was probably made from sulfur dioxide removed
from flue gas of an oil-fired boiler or from tailgas of a Glaus sulfur plant.
By-product gypsum from flue gas of a coal-fired unit might contain impurities
that would affect wallboard manufacture. This would have to be evaluated
by the wallboard manufacturers.
Industry sources have indicated that limited expansion may occur
at existing facilities, but that no new wallboard plants are anticipated
in the immediate future.
Discussion of Available Gypsum Markets
There may be limited opportunity for utilities near existing
wallboard plants in Ohio to sell by-product gypsum. The potential
market is about 350,000 tons per year. The power plants located between
Toledo and Cleveland appear to be best situated to sell by-product gypsum.
Because they are located near calcining plants, transportation cost would
be minimized. This does not necessarily mean gypsum manufacture is a
practical alternative for these plants. Detailed venture analyses would
be required to justify such a conclusion.
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It remains to be demonstrated that the by-product gypsum is suitable
for manufacture of wallboard in the United States. Furthermore, the current
gypsum manufacturers may resist purchase of gypsum from the utilities because
it would require that they shut down captive mines. Such details are best
negotiated between the principal parties and are beyond the scope of this
investigation.
Ammonium Sulfate •
Applications
Essentially all of the ammonium sulfate consumed in the United
States is used as fertilizer. Ammonium sulfate is used in fertilizers both
as a source of nitrogen and as a source of sulfur. To date, sulfur has
been an important consideration in fertilizer formulation in only a few
areas of the United States, but if sulfur dioxide is removed from utility
gases, then the soil in many areas of the United States may eventually
become deficient in sulfur. At the present time, sulfur deficiencies are
recognized in California and in portions of the southeastern United States.
It is primarily in these areas where the consumption of sulfur-containing
fertilizers (ammonium sulfate and normal superphosphate) is largest
Ammonium sulfate contains about 21 percent nitrogen, which is a
relatively low analysis when compared with urea (46 percent) and ammonium
nitrate (33.5 percent). The industry prefers to use the higher analysis
fertilizers in order to minimize the transportation, storage, and handling
costs per unit of nutrient. About half of the ammonium sulfate used as
fertilizer is applied directly, the other half is used in the manufacture
of granulated mixed fertilizer.
The physical form of a fertilizing material is important.
Ammonium sulfate is recovered from most processes as rather fine
crystals which have a tendency to create severe dusting problems. Such
ammonium sulfate is not suitable for bulk blending operations. In recent
years, the trend in the fertilizer industry has been towards increasing
use of bulk blending to manufacture mixed fertilizers, with a corresponding
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52
decline in granulation for the manufacture of mixed fertilizers. This
decline in granulation plants is expected to continue. Because of this
trend, the markets for ammonium sulfate in the northern farm areas are
not expected to increase. TVA is currently looking into the development
of mixtures of urea and ammonium sulfate fertilizers. Such fertilizers
would be particularly useful in sulfur deficient soils. They would,
however, probably be manufactured at urea plants located primarily on
the Gulf Coast.
Supply
In the eastern United States, all of the ammonium sulfate produced
is by-product material. Much of this by-product ammonium sulfate is
derived from coke ovens. The manufacture of ammonium sulfate from coke
oven gases has been practiced for several years by the steel companies as
a means of limiting emissions to the atmosphere. The ammonium sulfate
capacity from the steel companies in Ohio is estimated at over 95,000 tons
per year, and in* neighboring states this capacity is estimated at about
280,000 tons per year. Other sources of by-product ammonium sulfate
include Standard Oil's acrylonitrile production plant at Lima, Ohio.
Considerable by-product ammonium sulfate is also derived from
caprolactam manufacture, but none of this is near Ohio.
In 1971, U.S. production of by-product ammonium sulfate from
coke ovens was 539,000 tons and chemical by-product ammonium sulfate was
*
1,214,000 tons. Production in Ohio and neighboring states is estimated
at about 200,000 to 250,000 tons per year.
Consumption
In fiscal year 1972, the U.S. consumption of ammonium sulfate
for direct application in fertilizer was about 2.1 million tons. About
45 percent is consumed in direct application and the remainder is consumed
* U.S. Bureau of Census, Current Industrial Reports, M28A(71)-14, Inorganic
Chemicals, 1971, Washington, D.C. (1972).
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53
in mixed fertilizers. Data are not readily available on the consumption
of ammonium sulfate in mixed fertilizers by region. Nevertheless, it is
estimated that the consumption of ammonium sulfate in mixed fertilizers in
Ohio in fiscal 1972 did not exceed 48,000 tons. Ohio consumption of
ammonium sulfate for direct application was 16,747 tons in fiscal 1972.*
The consumption of ammonium sulfate for direct application in Ohio in
fiscal 1972 was down from consumption of 22,657 tons in fiscal 1971.
For the entire East North Central region in fiscal 1972, consumption of
ammonium sulfate for direct application was '48,554 tons.
Much of the ammonium sulfate has been exported from the United
States, primarily under AID-financed programs. Thus the overall market-
ability of ammonium sulfate has in the past depended to a large extent
upon export markets and especially on Government-subsidized sales in
export markets. Ohio utilities are not well located to participate in
these export markets.
i
Discussion of Ammonium Sulfate Markets
It appears that the demand for ammonium sulfate in and near Ohio
is more than adequately supplied by by-product material made in Ohio and
neighboring states. Furthermore, unless Ohio soils become sulfur defi-
cient as a result of removal of sulfur dioxide from utility flue gas,
ammonium sulfate will remain a rather undesirable fertilizer material.
Finally, even without competition from other by-product ammonium sulfate
made in the area, the entire Ohio 1972 consumption could have been supplied
by one 200 to 250-mw generation station.
It does not appear practical at present to market large amounts
of ammonium sulfate from Ohio utilities. However, there is some possibility
of "no-cost" disposal of limited amounts by export firms involved in the
international fertilizer market. The marketing of ammonium sulfate in the
rice growing regions of Texas, California, and some other Western states will
not be profitable, but might be preferable to the costs of operating a
throw-away emission control process.
* U.S. Department of Agriculture, Consumption of Commercial Fertilizers
for fiscal year ended June 30, 1972, Washington, D.C. (May, 1973).
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Sodium Sulfite
Although it would be relatively easy to absorb sulfur dioxide
from flue gases in a caustic solution to manufacture sodium sulfite, the
market for this chemical is limited. In 1971, the total U.S. production of
sodium sulfite was 204,000 tons.* Between 1967 and 1971, the market
fluctuated between this low figure and a high of 250,000 tons. A modest
growth rate of about 3 percent per year through 1976 has been projected.**
The paper industry is the major consumer of sodium sulfite. An
estimated 80 percent of the sodium sulfite is used in the neutral sulfite
semi-chemical pulping process. The remainder is consumed in water treatment,
photography, and miscellaneous applications. Many paper mills have captive
sodium sulfite capacity, but some of these are expected to return to purchasing
the chemical in the merchant market. Captive capacity of paper mills has been
estimated at 500,000 tons, compared with total merchant capacity of 267,000
tons. In the Ohio region, most of the sodium sulfite is supplied either from
the Koppers plant in Petrolla, Pennsylvania or by Reichhold from their
Tuscaloosa, Alabama plant.
There are two pulp mills in Ohio using the neutral sulfite, semi-
chemical process. Container Corporation in Circleville purchases sodium
sulfite. The other sulfite pulp mill, owned by Stone Container Corporation
in Coshocton, is currently testing a new pulping process which does not use
sulfur compounds. If they were to convert back to the sulfite process, the
total market for sodium sulfite in Ohio would probably be less than 25,000
tons per year. Even if the markets at sulfite mills in western Pennsylvania,
Indiana, and Kentucky could be penetrated, this would increase the market by
only an estimated 35,000 tons annually.
Another factor which should be considered is that paper mills in the
midwestern United States generally burn high-sulfur coal to generate steam
for their operations. If emission controls are applied to these industrial
* U.S. Department of Commerce, Current Industrial Reports, Inorganic
Chemicals, 1971, Series M28A (71)-14, Table 4 (October, 1972).
** Chemical Marketing Reporter, 201, 9 (April 10, 1972).
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55
boilers, it is likely that they would.recover the sulfur in a form which
could be used in their operations.
It appears that the sodium sulfite market is currently too small
to provide a practical outlet for sulfur recovered from utility flue gas.
This market is apt to shrink if sulfur emission controls are enforced against
owners of industrial boilers.
The potential market for sodium sulfite is insignificant compared
to the quantities of sulfur emitted by even a small (200 MW) utility plant.
gulfur Dioxide
Although several of the flue-gas desulfurization processes
concentrate the sulfur dioxide present in the flue gas as a part of
the recovery process, no process is designed specifically to recover
liquid sulfur dioxide by purification and compression. It is not
feasible to ship sulfur dioxide in the gaseous form and, therefore,
the entire merchant market for sulfur dioxide is for the liquid.
Although growing, the markets for sulfur dioxide itself
are small and diverse. The reported U.S. capacity for sulfur dioxide
is 154,000 tons.* 1971 production of sulfur dioxide was 95,414 tons.**
During the period between 1967 and 1971, shipments of sulfur dioxide
have fluctuated between 83,000 and 101,000 tons. Thus, it appears
that a small generation station with a capacity of 500 to 550 MW
could supply the present United States requirements for merchant
sulfur dioxide.
Because of the fluctuations in demand for sulfur dioxide, the need
to store it under pressure, and the expense of shipping it to distant loca-
tions throughout the country, production of such large quantities might
not be practical. The manufacture of sulfur dioxide from elemental sulfur
provides considerable flexibility, since production can be easily adjusted
to fit demand.
* Stanford Research Institute, 1973 Directory of Chemical Producers.
** U.S. Bureau of Census, Current Industrial Reports Series M2A (71)-14,
"Inorganic Chemicals", 1971, Washington, D. C. (1972), p 14.
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56
Manufacture of liquid sulfur dioxide does not appear at present
to be a practical alternative for most Ohio utilities. However, a detailed
cost analysis of the transportation cost of SO. versus the cost of convert-
ing S09 to sulfur, transporting the solid, and then reoxidizing to SO,,
and finally to SO, seems warranted at this time .
MARKETING PRACTICE FOR BY-PRODUCT SULFUR COMPOUNDS
Utilities Experience in the United States
The electric utilities in the United States have had no sub-
stantial experience in marketing chemicals. A few utilities do attempt to
market flyash which is recovered as a by-product from the generation of
electricity,, Many others, however, either discard the flyash or attempt
to sell by-product flyash through brokers. As a general rule, the utilities
have not yet developed the marketing experience and the distribution
channels to sell the by-product sulfur compounds which might be recovered
from flue-gas desulfurization processes. Many also recognize that diversi-
fication into an unfamiliar area like chemicals would require a major commit-
ment of management effort. Therefore, the practice for marketing by-product
sulfur compounds has been for the electric utility to market through an es-
tablished chemical company.
Although the arrangements for marketing by-product sulfur compounds
are made directly between the utility and the chemical company, the vendor
of the flue-gas desulfurization equipment is usually instrumental in bringing
these parties together. In fact, this service on the part of the vendor is
an integral part of the sales effort.
Some specific examples of the experience in marketing by-product
sulfur compounds from utility flue gas are described below.
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57
Illinois Power
A demonstration unit for the Monsanto Cat-Ox process has been
installed at the Wood River Station of Illinois Power. Although there have
been several operating problems with this process at Wood River, Monsanto
estimates that approximately 70 tons sulfuric acid will be produced per day
once operating problems have been solved.
Monsanto has agreed to market all sulfuric acid produced at
the Wood River demonstration plant. This marketing arrangement is in the
form of a 5-year contract with provisions for renewal. The net revenues
are split with 75 percent to Illinois Power and 25 percent to Monsanto.
Monsanto would expect to offer their marketing expertise to other utilities
purchasing a Cat-Ox system. Therefore, Monsanto would make a market survey
to ensure the acid could be sold before recommending Cat-Ox at any specific
location.
Boston Edison and Potomac Electric Power
The first prototype of the Chemico/Basic magnesia scrubbing process
was installed on an oil-fired boiler at Boston Edison's Mystic Station.
The flue gas from a 150-MW unit is treated with magnesia, and the sulfur
is removed in the form of hydrated magnesium sulfite. This magnesium
sulfite is dried to remove free water and the water of hydration. The
magnesium sulfite is then transported by truck to the Essex Chemical sul-
furic acid plant at Rumford, Rhode Island, where sulfur dioxide is re-
generated and made into sulfuric acid. Magnesia regenerated at the same
time as sulfur dioxide is returned to Boston Edison. Although there were
some start-up difficulties with this process, it was reported on stream in
July, 1973, and operating at 85 percent availability.
The current operation at Boston Edison is a pilot demonstration
of the process and cannot be considered a typical commercial operation.
The Essex Chemical sulfuric acid plant at Rumford is very small, old, and
had been scheduled for shutdown. The plant was originally built in 1926
and has a rated capacity of 50 tons per day. Arrangements were made to
add a calcining unit to process the magnesium salts and to continue operation
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58
of this sulfuric acid plant for the duration of the testing of the Mystic
prototype installation. A second Chemico unit using the magnesia scrubbing
process is currently being installed at Potomac Electric Power Company's
Dickerson Station. Half of the flue gas from the Dickerson #3 unit will be
treated, and the magnesium sulfite will also be shipped to Rumford for con-
version to sulfuric acid. The Dickerson #3 boiler is a coal-fired unit
rated at 190 MW. Upon completion of these two demonstrations, the Rumford
acid plant will be closed.
Of commercial significance would be the marketing of magnesium
sulfite or sulfuric acid from the #4, #5, #6, and #7 units at the Mystic
Station. The first three are each 150 MW and #7 is a new 600-MW unit.
This project is still in the planning phase. Negotiations are currently
underway between Boston Edison and several acid companies operating within
shipping distance of the Mystic Station*. Boston Edison expects to decide
whether to install additional scrubbing units or to burn low-sulfur fuel oil
at these units by October 1, 1973. Since the possible marketing arrange-
ments are still in the negotiation stage, no information is available on
marketing sulfuric acid from the commercial installation at this time.
Chemico is participating in the negotiations and is deeply involved in
identifying potential customers for the sulfur dioxide.
Philadelphia Electric
Philadelphia Electric Company is installing a prototype sulfur
dioxide removal system on its coal-fired Eddystone #1 unit. The Eddystone #1
prototype will handle flue gas from the equivalent of 120 MW. It is the
only recovery scrubbing system in the United States which is entirely funded
by the utility with no EPA or other governmental monies are involved.
The Eddystone prototype is a magnesia scrubbing system designed
by United Engineering & Constructors, Inc. In addition to the design and
engineering, United Engineers was instrumental in locating a customer for
* The logical candidate appears to be Monsanto at Everett, Mass.
The Mystic Station is also in Everett and is near the Monsanto plant.
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59
the sulfur dioxide to be regenerated. Although United Engineers assisted
in the arrangements for marketing the by-product, the final negotiations
were made directly by Philadelphia Electric. There were several potential
customers in the Philadelphia area. With the assistance of United Engineers,
Philadelphia Electric has reached an agreement with Olin Corporation who
will take the regenerated sulfur dioxide at its Paulsboro, New Jersey
sulfuric acid plant.
Sulfur dioxide will be removed from the flue gas at the Eddystone #1
station in Philadelphia. The sulfur removed at this location exits from the
process in the form of dry magnesium sulfite. The magnesium sulfite will
then be transported by truck to Olin's sulfuric acid plant which is about
20 miles from the power generation station by road. It is expected that a
round trip by truck will take about 1.5 hours. The transportation cost has
not yet been determined.
At Paulsboro, the magnesium sulfite will be processed to regenerate
magnesia and a gas containing about 17 percent sulfur dioxide. The magnesia
will be returned to Eddystone for reuse in scrubbing. The sulfur dioxide
will be sent to the contact sulfuric acid plant. The regeneration unit which
converts the magnesium sulfite to sulfur dioxide will be owned by Philadelphia
Electric, although it will be located at Olin's site and will be operated
by Olin. The magnesium containing salts will be owned by Philadelphia
Electric throughout, and title to the sulfur dioxide will be transferred
at the regeneration unit.
The Olin sulfuric acid plant in Paulsboro currently burns
elemental sulfur and reprocesses acid sludge to manufacture sulfuric acid.
Sulfur dioxide from the Philadelphia Electric prototype unit will constitute
only a small portion of its feed. Both Philadelphia Electric and Olin regard
this as a research project.
Neither Philadelphia Electric nor United Engineers believe that
it would be feasible to ship large quantities of magnesium sulfite from
treating all flue gas of a typical power plant to a sulfuric acid plant.
Rather, they believe that the sulfuric acid plant should be constructed at
the electric generation station.
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Northern Indiana Public Service
Northern Indiana Public Service Company (NIPSCO) is currently
installing a Davy Powergas/Allied Chemical demonstration unit to
desulfurize flue gas at the Mitchell station. The Davy Powergas technology
will be used to recover and concentrate sulfur dioxide, and the Allied
Chemical system will produce elemental sulfur. The project is funded by
EPA.
Allied Chemical will have a management contract to operate both
the Davy Powergas unit and the Allied reduction unit. Allied will also
market the by-product sulfur and any sodium sulfate obtained from the Davy
Powergas unit. The proceeds from the sale of the chemical will revert to
NIPSCO.
Allied considers its arrangement with NIPSCO as fairly typical of
the manner that they would approach the sale of sulfur from installation of
any other Allied process units. The Allied reduction technology can be
applied to any scrubbing technology which regenerates concentrated sulfur
dioxide, and is not necessarily limited to use in conjunction with the
Davy Powergas system. Allied prefers long-term contracts for the life of
the scrubbing unit for such arrangements. A possible alternative would be
5-year renewable contracts.
*
Markets in Japan for By-Product Sulfur
Atmospheric emission of sulfur dioxide is under national control
in Japan with progressive increasing limitations on emissions. Controls
are based on ambient standards of SO. concentrations that are to be
achieved by 1978. These standards are to be met by three simultaneous
*This section on Japanese markets is adapted from two reports:
a. Elder, H. W., Princiotta, F. T., Hollinden, G. A., and Gage, S. T.,
"Sulfur Oxide Control Technology. Visits in Japan-August, 1972",
Interagency Tech. Committee, Division of Chemical Development,
Tennessee Valley Authority, Muscle Shoals, Alabama (October 30, 1972).
b. Ando, Jumpei, "Utilizing and Dispusing of Sulfur Products from Flue
Gas Desulfurization Processes in Japan", Special Reports to Control
Systems Division, Environmental Protection Agency, Research Triangle
Park, North Carolina (May, 1973).
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programs: (1) to desulfurize residual oil remaining after distillation
of volatile portions, (2) to import low-sulfur crude oil, and (3) to
remove SCL from flue gases. The recovery of sulfur by-products in the
past has been prompted by the limited supply of Japanese sulfur and the
consequent cost advantage over products based on imported sulfur.
Sulfur products which have been successfully marketed in Japan
include elemental sulfur, sodium sulfite, sodium sulfate, sulfuric acid,
and calcium sulfate (gypsum). Because of oversupply, ammonium sulfate is
no longer marketed but is discarded by three plants still producing it.
Installations for Recovery of By-Product Sulfur
Japan is in a period of transition from sulfur recovery for
marketing of by-products to the installation of additional units primarily
directed to controlling emissions. For these latter units, there is no
assured market; especially so, because the capacity for recovered sulfur
is expected to grow extremely rapidly. For example, nine major power
companies producing 70 percent of Japan's electrical power are turning to
flue gas desulfurization very strongly as the limitations on sulfur
emissions become more stringent. Desulfurization systems had been installed
for flue gas treatment in power plants with a total capacity of 357 MW in
1972, and new installations are expected to increase the total capacities
to 2,700 MW in 1974 and 4,800 MW in 1976. The 13-fold increase projected
for a 4-year period includes various methods of flue-gas treatment which
produce both throw-away materials and useful by-products.
In the past, installations in Japan for sulfur recovery were
justified largely by their yield of salable products. Now, there is more
similarity in the situation for sulfur recovery and marketing between
the Ohio utilities and the Japanese marketing experience:
(1) New installations will be facing a relatively saturated
market for sulfur products in both places, and will be
competing on the basis of price rather than profitability.
(2) A very low proportion of the electrical generating capa-
city is currently treated for flue gas desulfurization.
Even with planned installations, only about 10 percent of
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electrical generating capacity in Japan will be treating
flue gas in 1976.
(3) The total area covered by the industrialized regions of
Japan's main island of Honshu is not far different from
the total area of the Air Quality Control Regions wholly
and partially in Ohio. These areas are both served by
water transportation; Ohio has the Ohio River and the Lake
Erie ports, while Honshu is an island between the Sea of
Japan and the Pacific Ocean.
(4) The total annual emissions of S02 in the two regions are
similar. About 6 million tons of SO was emitted in Honshu
in 1971 while burning heavy oil, which is the chief source
of S0? in the atmosphere. In the same year, it is estimated
that the total utility SO in the Air Quality Control Regions
of Ohio was about 4 million tons.
There are three significant differences that impinge upon this
study of by-products:
(1) Many sulfur chemicals have a higher value in Japan than in
the United States. The greatest price differential is for
gypsum.
(2) Honshu has a population of six to eight times that of
Ohio, so that the efforts to find valuable by-products
markets to support the denser population were started
earlier and explored in more detail. Thus, the experience
may be helpful to Ohio utilities now faced with a similar
necessity.
(3) Much of the fuel for power generation is heavy fuel oil
rather than coal as in Ohio. Both have high sulfur con-
tent of the order of 4 percent, but the impurities intro-
duced into by-products may be lower from oil-derived
particulate matter than from fly-ash in the flue gases
from coal.
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Elemental Sulfur. By-product elemental sulfur is produced pri- .
tnarily in Japan by removing sulfur from heavy fuel oil before it is burned.
About one-fourth of the total heavy oil was desulfurized in 1971, giving
256,000 long tons of sulfur as a by-product. Additionally, by-product sulfur
from other sources, such as oil refining, increased the supplies to the
point where recovered sulfur represented 90 percent of the total in 1971
and 97 percent of the total elemental sulfur in 1972.
Elemental sulfur has two advantages with the oversupply of sulfur
that is in prospect in Japan. If it is not salable, it can be stored
indefinitely for eventual recovery. This would be an alternative to
finding immediate markets, even though the prospective need for its
recovery is not certain. It occupies the smallest volume and requires
the least transportation and storage space. The second advantage is that
it can serve as a starting point for any of the other sulfur compounds
that may find use in the future. The route to sulfuric acid, for example,
is by way of combustion of the sulfur with air to sulfur dioxide, and then
the manufacturing process proceeds from there.
Sulfuric Acid. Sulfuric acid is the most important acid for
industrial uses in Japan as it is in the United States. Various processes
have been and are being installed for sulfur recovery from waste gases which
give sulfuric acid as the marketable end product. In 1972, the total
sulfuric acid production was over 7 million tons of which almost 60 percent
was by-product acid produced from the sulfur dioxide recovered from smelter
off-gases. Only 4 percent was made by burning of elemental sulfur to sul-
fur dioxide, and the remainder was from roasting of pyrite. It appears
that Japanese industry has no unique processes or marketing procedures
for sulfuric acid that are not already available to the United States.
It is possible that the prospective increase in recovery of sulfur dioxide
from industrial waste gases will continue to cause the reduction of use of
pyrite for sulfuric acid. However, pyrite is more easily stored to meet
fluctuating markets for sulfuric acid than is sulfuric acid produced from
recovered S02.
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Sodium Sulfite. One widely used paper-making process consumes
sodium sulfite in the preparation of paper pulp from raw wood. Since
sodium sulfite solution is the absorptive agent for sulfur dioxide in major
processes for flue-gas clean-up, as already discussed, and more is formed
during absorption, this surplus amount represents a significant direct out-
let for the by-product sulfur as an alternative to regeneration for recovery
of S02. In the 5-year period from 1967 to 1971, in Japan, the production of
sodium sulfite tripled to reach 330,000 tons, of anhydrous material, most
of which presumably went into paper making. However, the sale price also
started to decrease as a result of oversupply, and the future demand is
definitely limited.
Sodium sulfite recovery differs in the final treatment of the
absorbing solution from the process for recovering sulfur dioxide. During
absorption, sulfur dioxide combines with sodium sulfite to form sodium
bisulfite. Then this product is converted to sodium sulfite by neutrali-
zation with the alkali, sodium hydroxide. One-half of the resulting
sodium sulfite solution is recycled to be used as absorbent, and the other
half is evaporated to form crystalline solid sodium sulfite for sale.
Calcium Sulfate (Gypsum) and Calcium Sulfite. According to
Ando*, gypsum is the preferred by-product in Japan. It has two major uses
there: (1) for retarding the rate of setting of Portland cement, and (2)
as the major component for certain types of wall tile, wallboard, lath,
and various kinds of plasters. The demand for gypsum in Japan is projected
to increase by about 50 percent between 1970 and 1976. In 1970, the demand
and supply were balanced at about 4,000,000 tons.
There are two important sources of by-product gypsum, of which
the earlier one is gypsum recovered from the manufacture of superphosphate
fertilizer from phosphate rock. The other major source is from recovered
sulfur, which is expected to supply a large part of the projected increase
in demand, because of increased recovery of sulfur values to reduce
emissions. Furthermore, gypsum is reputedly more desirable for landfill
than calcium sulfite if it must be disposed of because of lack of markets.
It is claimed to be more easily dewatered than calcium sulfite to form a
stable fill that is relatively inert and innocuous.
*Reference page 60.
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Some tests have already been made in Japan by Mitsui Aluminum
Company, which has produced wallboard from by-product calcium sulfite
recovered by treating coal-fired flue gas with the Chemico-Mitsui process.
Gypsum is produced from the calcium sulfite by oxidation. The gypsum
contains slightly more than 10 percent impurities, including fly ash and
other materials. It is expected that the strength of the wallboard manu-
factured from this typsurn will be up to-required specifications. Plans are
being made for an industrial scale operation to produce wallboard from
this by-product process in 1974.
Ammonium Sulfate. Ammonium sulfate is a by-product of scrubbing
the flue gases with ammonia solution. It has been produced in several
ammonia scrubbing plants but is not a saleable product in the present
markets open to the Japanese. One plant producing solid ammonium sulfate
is converting that product into gypsum, which can be sold in Japan. This
is not a feasible alternative in the United States.
By-Product Specialties. The prospect of market saturation for
by-product sulfur induces close attention to any prospect for developing
new specialty products that can be protected by patents, and thus create
new and profitable markets. Until patents are published, development work
is usually highly proprietary. One patent has recently been issued* des-
scribing the precipitation of calcium sulfite in a form useful as a filler
for plastics. Control of the conditions of precipitation undoubtedly
permits better control of surface properties, hydration, crystal shape,
and particle size so as to impart desirable characteristics to the filler.
It has been noted earlier that calcium sulfite is less desirable than
calcium sulfate as a landfill, because the sulfite has a smaller particle
size, which makes it difficult to handle. This process presumably takes
advantage of the controllable properties of calcium sulfite that are
favorable to superior performance as a filler for plastic materials.
*U. S. Patent 3,739,060, "Method of Preparing Calcium Sulfite for Use as
a Filter for Plastics", assigned to Lion Fat and Oil Company Limited,
Tokyo, Japan (June 12, 1973).
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There have also been announcements this year of other new mater-
ials already in trial production. One is a gypsurn-polymer composite,
which is indicated to be a filled plastic suitable for severe duty construc-
tion use that requires more resistance to abuse than wallboard. A synthetic
paper is a heavily loaded plastic film containing about 70 percent of
specially prepared calcium sulfite. It was announced that this paper
could command a premium price because of superior properties.
Significance of Japanese Experience for Ohio Utilities
Japanese industry, when faced with the necessity for reducing
sulfur emissions by removing and perhaps recovering sulfur for reuse,
has attempted to solve problems very similar to those facing the Ohio
utilities. It appears that these attempts have been pointed toward three
activities. First, installations have been made to produce materials for
present markets, when an expanding market was predictable, and the compe-
titive sources of supply did not have an overwhelming advantage. This
appears to have been the situation that prompted the expansion in produc-
tion of gypsum as a by-product. Both major uses, for wallboard and as a
concrete additive, required substantial amounts of gypsum and these indus-
tries were expanding. Major competition came from gypsum recovered by a
fertilizer industry, which presumably was already better established and
did not have the same incentive to expand as other industries.
Second, Japanese industries seek flexibility of the process to
permit several by-products, if possible. A Battelle representative who
visited Japanese installations in July, 1973, reported three plants with
oil-fired boilers had installed the Chiyoda process, two of which were
operating and one under construction. This process washes the flue gases
with slightly acidified water to absorb SO^. The concentration of the
collected washings is about 4 percent acid. These are partially
neutralized with limestone to convert the acid to gypsum of commercial
quality. Gypsum is also the preferred low-cost throwaway product in Japan,
which permits some versatility in the operation.
Elemental sulfur also is viewed favorably for Japanese plants
because it can be stored indefinitely at least expense, and then supplied
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as the feed for any process to make sulfur-containing materials, when
the market is favorable. However, it would not be selected initially
unless there were already a fluctuating demand for sulfur and only a
periodic oversupply.
Third, the Japanese are searching for new uses for sulfur by-
products that may reach a substantial volume of production. These
include other construction materials in addition to wallboard, and fillers
for plastics and synthetic paper as already described.
Sulfur Recovery from Fossil Fuel Processing
Producers of the three classes of fossil fuels, natural gas, petro-
leum, and coke, have a significant technological advantage over Ohio utilities
when they are required to limit sulfur emissions. Whereas the utilities
must handle sulfur dioxide in flue gases, the fuel producers have available
to them a more attractive side stream of surplus hydrogen sulfide which is
separated from their primary products during the purification treatments.
Hydrogen sulfide is itself also a fuel that can be used for energy produc-
tion by combustion; the side stream is much more concentrated in hydrogen
sulfide than are the flue gases of the utilities in sulfur dioxide; and the
hydrogen sulfide is a reducing agent for production of elemental sulfur
from sulfur dioxide. Thus these producers have a number of options for
recovering costs and perhaps profiting from their sulfur-containing impurities,
If there is a market for sulfur they can burn one-third of their supply of
hydrogen sulfide in air and combine the combustion product sulfur dioxide
with the remaining unburned hydrogen sulfide to produce sulfur. If there
is no market for sulfur this solid product can be stored or disposed of at
minimum cost, as noted previously. Generally speaking, capital costs are
relatively low, and no significant inputs of energy or additional materials
are required. If a market exists for sulfuric acid, the by-product stream
of hydrogen sulfide can be burned completely to sulfur dioxide with air
and the combustion products can be sent to a sulfuric acid plant.
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The competitive advantages of having several alternatives can only
be met by finding superior marketing arrangements for the Ohio utilities, on
the basis of preferred location relative to market, or special situations.
Natural Gas Producers
Many natural gas wells contain hydrogen sulfide as one component
of the gas mixture. This must be removed because of the corrosive nature
of the sulfur dioxide produced when it is burned. Substantial amounts of
elemental sulfur were produced in 1970 from natural gas, with Texas accounting
for about 75 percent of the total production. There is also a large amount
of sour gas treated from the fields of Alberta, Canada, with recovery and
storage for marketing of high tonnages of elemental sufur. These two
regions represent the major sources of competition for sulfur by-product
markets of the Ohio utilities.
Petroleum Refining
The locations of petroleum refiners are much more widely scattered
than are the gas fields with high hydrogen-sulfide content. Thus, by-
products from petroleum refiners will tend to supply local or regional
markets first and will not block out from consideration large areas of
potential markets for Ohio utilities' sulfur. However, the petroleum
refiners have the same technological advantage as the natural gas producers,
because they,'too, start with hydrogen sulfide in their by-product stream.
Here, too, the Ohio utilities cannot compete technologically, and their markets
are local or require special situations. ,
. r
!•
Coke Production
By-product coke ovens have usually recovered only liquid products
for sale and have used the combustible off-gases as process fuel. These
off-gases included a substantial amount of hydrogen sulfide which was
discharged to the atmosphere as its combustion product sulfur dioxide.
Increased attention to pollution controls on coke oven installations has
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prompted recovery procedures to separate hydrogen sulfide before the off-
gases are burned. One example is the Clairton works of United States Steel,
which has had hydrogen sulfide recovery as a control measure for several years.
This hydrogen sulfide stream is converted to elemental sulfur.
It is probable that sulfur products from coke ovens will have some
impact on the marketability of sulfur products within the areas otherwise
available to Ohio utilities. This example is cited to show that pressure for
antipollution controls on all industries with sulfur emissions will favor the
growth of available sulfur supplies and incidence of surpluses as control
measures are implemented.
Development of Technology and Markets by Smelters
Technology of Ore Smelting
The nonferrous smelters recover copper, lead, and zinc metals
from their sulfide ores by stepwise processing with heat and fluxes to
form a melt of crude metal and slag, which separates into layers. The
bottom layer of metal is withdrawn for further refining, and the nonmetallic
slag is discarded. The off-gases from the processing steps carry sulfur
dioxide derived from the sulfide portion of the ore. In general, the sulfur
dioxide concentration in smelter off-gases is substantially higher than can
be expected in the flue gas from combustion of high-sulfur coal by the Ohio
utilities. Recovery costs are correspondingly lower, and some smelters have
found it profitable for many years to sell by-product acid manufactured from
the recovered S0_.
The smelting of nonferrous ore usually starts with a roasting step,
in which ore concentrate is heated in the presence of air. A part of the
iron sulfide also present in the concentrate is converted to elemental iron
plus sulfur dioxide in the off-gases. These contain about 2 to 6 percent SO,
when a multiple hearth roaster is used. Optimum sulfur dioxide concentration
for sulfuric acid manufacture is 8 percent or above, but these gases could be
processed directly in a sulfuric acid plant after cleaning and cooling. An
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alternative roaster uses a fluidized bed in which fine ore particles are
partially suspended and violently mixed in a heated, upward-flowing air stream
that balances the tendency of the particles to fall by gravity. Because of
the better efficiency of mixing and contact between air and ore in the fluidized
bed, less air needs to be used, and SO- in the off-gases may have concentrations
of about 12 percent. Fluidized beds have been used most commonly for lead or
zinc ore, although copper smelters may be prompted to turn more to this method
in the future in an effort to lower costs while meeting antipollution regulations,
The next step in treatment of copper ore feeds the roasted ore into
a reverberatory furnace together with a solid flux in a mixture that is melted
on the floor of the furnace by radiated heat from the flame above the surface
and from reflections off the hot roof of the chamber. When the flux reacts
with the roasted ore a metallic phase is set free that settles to the bottom
of the pool as a denser liquid layer with the lighter molten slag floating on
top. Each layer is withdrawn periodically from its own tap hole at the
appropriate level in the furnace wall or bottom. In this step of the
process about 10 to 20 percent of the sulfur content of the charge to
the furnace is given off as sulfur dioxide mixed with the effluent combustion
gases. These gases contain less than one percent sulfur dioxide, and normal
practice has been to release them up the stack. However, the sulfur dioxide
concentration is higher than the 0.2 to 0.3 percent SO- expected from the
combustion of high-sulfur coal, and these gases will have to be treated.
It is not certain what the smelting industry will do to clean up
the gases from the reverberatory furnace to meet the limitations on source
emissions. There are two alternatives that have been used by foreign smelters.
Each of these gives off gases with higher sulfur dioxide concentration that is
more adaptable to by-product SO- recovery and sulfuric acid manufacture. The
electric furnace for copper smelting uses electrodes immersed in the slag
layer, which acts as the heat generator where current is passed through it
to the lower metallic layer as the opposing electrode. The total volume of
S0_ liberated is about the same as from the reverberatory furnace, but there
are no gases produced by combustion of fuel, so that a concentration of about
3 percent SO- can be attained. This process is economically feasible only
where low-cost electric power is available.
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Flash smelting furnaces have also been developed in which the ore
concentrates in the form of small particles are smelted directly without a
preceding roasting step. The particles can be burned by predrying the ore
concentrate powder and using preheated air in a manner similar to the burning
of pulverized coal suspended in air. The flux is also introduced in powder
form together with the predried concentrates of ore, so that the smelting
reactions take place in suspension and after they settle to the furnace floor
until the separate layers of molten metal and slag are formed. About 14 percent
S0_ gas concentration can be reached in this furnace using preheated air.
If pure oxygen is available at low cost it can be used in a similar
flash smelting furnace to burn flotation concentrates in the presence of
powdered flux. In this modification there is no dilution of the off-gases by
atmospheric nitrogen, so that concentration of S0? can be as high as 80 percent.
This alternative opens a wider market, because pure S0_ can be recovered for
sale as a liquid.
The metal layer tapped from the smelting furnace contains about
30 percent copper, 40 percent iron, and 26 percent sulfur. This copper
matte is transferred to a converter with more flux added to combine with the
iron while air is blown through the mixture from below the liquid surface.
Most of the iron combines with the flux in the top layer during blowing,
and is skimmed off for discard. The remaining layer of molten metal still
contains about 24 percent sulfur, which is oxidized to S0_ in the exhaust
gases by continuing the blowing with air. When blowing is completed the
copper layer is about 99 percent pure. The off-gases from the conversion
step commonly contain 2 to 6 percent S0_, because the converter exhausts
into an open hood and surrounding air is drawn into the hood to dilute the
rising hot gas. By special designs to reduce this air infiltration the
S0_ concentrations can be increased to more than 6 percent minimum.
This description of smelting steps shows that there are a number
of options available in each step to improve the traditional methods for
recovering sulfur dioxide by increasing the concentration of this gas in the
off-gas mixture. The trend is to exercise these options whenever new
installations are required to meet emission standards. Therefore, the amounts
of recovered sulfur dioxide will presumably increase in the nonferrous
metal smelting industry.
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This industry is in a position similar to that of the Ohio utilities
in the sense that it, too, is limited to the recovery of sulfur dioxide.
Unlike the processors of fossil fuels discussed in the preceding section,
there is as yet no easy route to hydrogen sulfide and from there to elemental
sulfur. However, the smelting industry has the inherent advantage of
reasonable options for increasing the concentrations of sulfur dioxide in
their off-gases, which is not available to the Ohio utilities except to a
limited degree by burning coal with higher sulfur content. Therefore, the
smelters can treat lesser quantities of gaseous emissions with lower costs
for the same amount of recovered SO^. Their competitive advantages can only
be met by superior marketing arrangements by the Ohio utilities, on the
basis of location of each utility or some other special market situation.
Smelter Marketing Experience
Eastern United States. Many of the metals companies which operate
smelters prefer not to market by-product acid or other chemicals. Many
smelters, therefore, have contracts with chemical companies to market by-
product sulfuric acid generated at the smelters. A typical contract would
require the chemical company to take all sulfuric acid produced at a smelter
at a price, f.o.b. smelter, which would be adjusted for fluctuations in
sulfur prices and possibly in labor rates. Most contracts have automatic
annual renewal clauses, with a 2-year notice required by either party to
terminate the contract.
There are currently three smelters in the Eastern United States
producing by-product acid which would be potentially in competition with
acid from Ohio utilities. These are the St. Joe Minerals zinc smelter at
Monaca, Pennsylvania, the American Smelting and Refining (Asarco) zinc oxide
plant at Columbus, Ohio, and the Cities Service smelter at Copper Hill,
Tennessee.
Of these three, St. Joe Minerals sells their acid to Allied Chemical,
f.o.b. smelter. Allied then markets the acid to end users". Allied frequently
cuts back production at its own sulfuric acid plants in the Ohio Valley in
order to accommodate this by-product acid.
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Asarco, on the other hand, markets their own acid from the Columbus
plant; Asarco does sell acid to chemical companies at other locations. Cities
Service markets acid from the Copper Hill smelter directly to the end-user.
Canadian Successes. One of the best examples of what can be done
by industry under proper incentive is provided by the Consolidated
Mining and Smelting Company of Canada, Ltd. (Cominco) plant at Trail, British
Columbia. The Trail plant of Cominco was started many years ago to treat
gold mine wastes (primarily a copper ore) from the Rossland mine. It now
recovers lead, zinc, silver, and a few more minor minerals from the Sullivan
mine at Kimberly, British Columbia, which is about 200 miles north of Trail.
In the late 1920's, Stevens County in the State of Washington
filed a suit which cited the company for the pollution being emitted by the
Trail smelter and case was eventually decided by the World Court. In
essence, the Court ruled that the Trail plant, which is located about 8 miles
north of the U.S.-Canadian border, would have to clean up its smelter and
sinter plant stack gases, which ran as high as 8 percent SO . Trail is a
village in an extremely deep canyon of the Columbia River^ and the mountains
tower above the stacks.
Cominco eventually developed a remarkably versatile ammonia
scrubbing system. All the off-gas from the sinter plant at Trail is
washed with ammonia solution. This stream represents 180 t/day of sulfur at
a concentration of 1.5 percent SO , and roughly 60 percent is recovered.
The off-gas from the zinc roasters is split into two streams. Roughly
580 t/day of sulfur is in zinc ore and about 10 percent of this is
absorbed in ammonia solution. The bulk of the S02 (at 8.5 percent cone.)
goes to catalytic oxidizers to burn the SO to S0_ and produce about
1600 t/day of sulfuric acid in three separate acid plants of varying
vintage. Some of the acid is used to react, with the ammonium bisulfate
solution from the scrubbers to produce SO , which is compressed to liquid
and sold at the rate of 120 t/day. At the present time the plant cannot
produce enough S0? to meet demand.
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The sulfur output of the plant breaks down roughly as follows -
about 5/8 of the sulfur is sold as sulfuric acid, 1/4 as SO , and 1/8 as
ammonium sulfate. SO. is sold as far away as Glen Falls, N.Y.; Hobbs, N.M.;
Los Angeles; and Alaska. The SO. market was initially quite small, but
Cominco takes some credit for its expansion. SCL normally is used for
bleaching dried fruit and in sugar beet production. However San Francisco
buys 200 t/year as a chlorine scavenger t.o clean up excess chlorine after
waste treatments. The use in Los Angeles is for oxygen scavenging to clean
up water before compression to flood oil wells. ' It is used in Manitoba for
pH control by a mining firm. Some SCL is also used in the manufacture or
use of chlorine dioxide and zinc and sodium hydrosulfites, all of which are
important in the paper industry (although the use of zinc hydrosulfite is
declining because of environmental considerations).
Cominco is the second largest SCL producer (65,000 t/year) in
Canada. The largest is Chemical Industries at Sudbury, Ontario (95,000
year), which until recently sold most of the product to an adjacent pulp
mill (the mill recently shut down). Virginia Chemicals and Essex are the
biggest S07 producers in the United States.
Cominco sells most of its sulfuric acid on the West Coast. How-
ever, substantial amounts are also sold in Calgary, despite the fact that
sulfur recovered from natural gas is available there in tremendous quanti-
ties. For many years ammonium sulfate was a major product and was shipped
to China for use as fertilizer.
The only serious plant problem still unsolved in the white plume
which consists of ammonium sulfate. Only about 2 tons/day of ammonium
sulfate goes up the stack with about 1 ton/hr of unreacted S0?, but the
crystals are extremely visible. A pilot mist eliminator is currently being
tested and appears promising. The S0« levels have now been reduced to about
1000 ppm, but this, of course, is too high a level for untreated utility
stack gases in the United States. The ammonium sulfate is considered by
Cominco to be harmless and the plant makes much use of attractive flowers
and shrubs on their grounds to show evidence of this .
The plant represents a good example of practical environmental
engineering. Although the process in the past has been considered to be
too expensive for use with utility stacks, this view may change as a
result of difficulties with the other alternatives open to utilities.
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CONCLUSIONS AND RECOMMENDATIONS
(1) The major outlet for sulfur by-products from all the Ohio
utilities probably would be in the Gulf Coast for phosphate fertilizer
production. A detailed study of the net process energy and cost require-
ments for production of sulfur, sulfur dioxide, and/or sulfuric acid in
Ohio and shipment and use in Florida and other southern states as sulfuric
acid is needed to determine at what price the Ohio utilities can compete in
this market.
(2) An alternative scheme to locate at least one phosphate
fertilizer plant in Ohio is conceptually promising and should be evalu-
ated in detail. Such a facility might supply the sulfur outlet necessary
for several of Ohio's major utility plants.
(3) The nearby surrounding states offer some market potential
tor Ohio utilities, but because of similar utility emissions, and possibly
similar regulations in some states, the additional markets available to
Ohio utilities is probably not large. Those Ohio utilities that are some-
what slow to react to the sulfur disposal problem will be forced to compete
in this somewhat limited and transportation cost-sensitive market.
(4) There may be a very substantial excess of sulfur as
emissions from Ohio utilities over the Ohio market needs for sulfur.
Those utilities that act rapidly, possibly in concert with current
producers, will quickly satisfy this market.
(5) Those utilities located near oil refineries in Toledo,
Cleveland, and elsewhere should consider combining plant effluents for
treatment in a Glaus process for sulfur production using the S0? from the
utility and H S from the refinery for the required feed streams.
(6) There may be a number of current special situations for
individual Ohio utilities where production of a limited market product,
such as gypsum or ammonium sulfate, might be preferable to all other
options open to those utilities.
(7) Because of the relative costs of shipping sulfur or its
derivatives compared with their low production costs, and because of the
substantial excesses of by-product sulfur expected in most parts of the
nation in the future, the market price for sulfur by-products from Ohio
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utilities will probably drop precipitously as control technology becomes
available during the next several years.
(8) Despite such a drop in price, the production of elemental
sulfur may represent one of the most attractive products. Sulfur is
relatively harmless from an environmental standpoint, and its disposal by
selling even at depressed prices might obviate the costs of disposal of
sludges produced by throw-away processes.
(9) In general, the production of any by-product which has
even limited value in the open market place is preferable to production
of by-products which have no value and require costs for disposal.
(10) In the long run, if sulfur emissions are fully controlled,
there might develop a need for substantial sulfur additions as fertilizer
to the soils in Ohio. This is not likely to occur, however, in the near
future.
(11) The support of active research and development efforts to
find new uses and expand the markets for sulfur by-products in order to
minimize the decline in price structure of the by-products of Ohio's
utilities is desirable.
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ACKNOWLEDGMENTS
The authors alone are responsible for the arrangement, expression,
and interpretations of the information presented in this report, but they
wish to acknowledge helpful interest and information from the following
members of the Battelie-Columbus staff: H. W. Barr, F. C. Croxton, J. M.
Genco, A. W. Lemmon, Jr., E. S. ,LipinsKy, an,d G. R. Smithson; the EPA
Project Officer, Mr. Rayburn M. Morrison; and from'staff members of the
organizations listed below:
Agrico Chemical Division of Williams Brothers
Allied Chemical Corporation
American Smelting and Refining Company
Boston Edison Company
Chemical Construction Company
Cities Service Corporation
Consolidation Mining and Smelting Company
Davy Powergas Company
E. I. DuPont de Nemours and Company
Fertilizer Institute
Mead Corporation
Northern Indiana Public Service Company
Philadelphia Electric Company
St. Joe Minerals Company
Sulfur Institute
U. S. Department of Agriculture
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