Pi
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Deriv urit
Processes Rese. Inc.
prepared for
mental Protection Ag
*RIL:
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BIBLIOGRAPHIC DATA
SHEET
4. Title and Subtitle
Neutralization
1. Report No.
EPA-R2-73-187 6 /
of Abatement Derived Sulfuric Acid
3. Recipient's Accesnmn M-
pient s Accesninn
PB-220 362
5* Report Date
April 1973
6.
7. Author(s)
W.D. Beers
8. Performing Organization Kept.
No.
9. Performing Organization Name and Address
Processes Research, Inc.
2912 Vernon Place
Cincinnati, Ohio 45219
10. Proiect/Task/Worlc Unit No.
Task Order 3
11. Contract/Grant No.
68-02-0242
12. Sponsoring Organization Name and Address
EPA, Office of Research and Monitoring
NERC/RTP, Control Systems Laboratory
Research Triangle Park, North Carolina 27711
13. Type of Report ft Period
Covered
Final
14.
15. Supplementary Notes
16. Abstracts The report presents a flow sheet and economics for neutralizing abatement
derived H2SO4 with milled limestone in an aqueous slurry. The resulting gypsum is
deposited in a settling pond and the supernatant is recycled to slurry fresh limestone.
The process is based on a literature review. Results of pertinent laboratory exper-
iments by American Smelting and Refining Co. are also discussed. Investment
requirements for neutralization facilities are approximately $775,000, $1,530,000,
and $2,875,000 (1972 dollars), respectively, for daily neutralizing capacities of 100,
350, and 1000 tons of H2SO4. When all of the H2SO4 is being neutralized, the
incremental abatement costs for neutralization are approximately $53, $36, and $28
per ton of sulfur, respectively. When all of the H2SO4 is being sold, so none is
neutralized, costs for the standby neutralizing facilities having daily H2SO4
capacities of 100, 350, and 1000 tons add about $5, $3, and $2 per ton of H2SO4,
17. Key Voids and Document Analysis.
Air Pollution
Boilers
Economics
Acid Treatment
*Neutralization
Sulfuric Acid
*Limestone
Desulfurization
Flue Gases
17b. Idemifiers/Open-Ended Terms
Air Pollution Control
Stationary Sources
Wet Scrubbing Processes
17*. Descriptors
Washing
Settling Basins
Slurries
*Gypsum
Expenses
respectively, to the acid
production costs. A biblio-
graphy is included.
17e. COSAT1 Field/Group
13B
18. Availability Statement
Unlimited
FORM NTia-98 (REV. 3-721
19. Security Class (This
Report)
UNCLASS1F1
LASS1F1EP.
Class (This
20. Security
Page
UNCLASSIFIED
21. No. of Pages .,
22. Price
U3COMM-DC'l4»32-P72
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EPA-R2-73-187
Neutralization
of Abatement
Derived Sulfuric Acid
by
W. D. Beers
Processes Research, Inc.
2912 Vernon Place
Cincinnati, Ohio 45219
Contract Ncr. 68-02-0242, Task No. 3
Program Element No. 1A2013
EPA Project Officer: G. S. Haselberger
Control Systems Laboratory
National Environmental Research Center
Research Triangle Park, North Carolina 27711
Prepared for
OFFICE OF RESEARCH AND MONITORING
U. S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D. C. 20460
April 1973
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This report has been reviewed by the Environmental Protection Agency
and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Agency,
nor does mention of trade names or commercial products constitute
endorsement or recommendation for us.
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ACKNOWLEDGMENT
Tae nuthor wishes to acknowledge the assistance of Messrs. R. I.
Tarver and G. N. Thomas in the development of this report, the helpful
guidance and critique by Messrs. G. S. Haselberger and M. R. Jester,
and the contributions to the report by American Smelting and Refining,
Company. In addition, the author wishes to acknowledge the many sources
of information used and referred to in the Bibliography.
V. D. Beers
ill
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NEUTRALIZATION OP
ABATEMENT DERIVED
SULFDRIC ACID
INDEX
Section
I
II
III
IV
Title
Introduction
Summary
Recommendations
Discussion
Page
I
2
5
9
Appendix
A
B
C
D
Process Flow Diagram
Process Economics
American Smelting and Refining Company Data
Bibliography
iv
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SECTION I - INTRODUCTION
In the abatement of air pollution from Industrial sources such as
smelters, large quantities of sulfurlc acid are produced. Sulfurlc acid
Is also produced by many of the abatement processes, such as the Monsanto
Cat-Ox Process, developed for comprehensive application to air pollution
sources, Including power generating plants. The growing oversupply of
world sulfur promises uncertainty of future markets for such acid.
From an earlier study (Appendix D, Item 34), It appears that the
neutralization of abatement derived sulfurlc acid with limestone may be
an economically and technically feasible answer to the problem of acid
disposal when acid markets are not available. Therefore,an investigation
was undertaken to define more fully the potential of this approach. This
Investigation was to include a pertinent literature search, conceptual
design, and flow sheet for the neutralization of abatement derived sulfuric
acid with limestone. Investment and operating costs were to be developed
for daily l^SO^ capacities of 100 tons, 350 tons and 1000 tons.
The conceptual design and economics discussed in this report are based
on review of literature. The results of pertinent laboratory experimentation
by American Smelting and Refining Company are also discussed.
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SECTION II - SUMMARY
In the process discussed herein, abatenent derived sulfuric acid is
neutralized with milled limestone in an aqueous slurry, and the resulting
gypsum is deposited in a settling pond. Supernatant from the gypsum disposal
pond is used to slurry the limestone. Using annual gypsum disposal ponds each
twenty feet deep, the number of filled ponds which may be left exposed, with
rainfall running off to the pond being filled, varies from two filled annual
ponds where annual rainfall is sixty inches, to eleven filled annual ponds
where annual rainfall is fifteen inches. Beyond this, the filled ponds must
be covered to prevent spilling supernatant into surroundings. Instead of
annual ponds, some pond cost saving might be achieved by construction of
larger ponds, depending on the number of years of acid neutralization
foreseen and on the pond area limits related to the expected rainfall.
The Investment requirements for neutralization facilities are approximately
$775,000, $1,530,000 and $2,875,000, respectively (1972 dollars), for daily
neutralization capacities of one hundred tons, 350 tons and 1000 tons of
H2S04. When all of the sulfuric acid is being neutralized, the incremental
abatement costs (1972 dollars) for neutralization are approximately $53, $36
and $28 per ton of sulfur, for neutralization facilities having dally H^SO^
capacities of one hundred tons, 350 tons and 1000 tons, respectively.
For example, smelter offgas pollution abatement acid plants are considered,
each producing 350 tons of HjSO^ daily, from offgas having different concen-
trations. The abatement costs for the acid production alone are approximately
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$78, $33 and $25 per ton of sulfur, for smelter offgas S02 concentrations of
two, six and twelve mole percent* respectively. Hence, the combined abatement
costs for acid production and neutralization are approximately $114, $69 and
$61 per ton of sulfur, respectively.
When none of the sulfuric acid is being neutralized, the incremental
abatement costs for neutralization are approximately $15, $9 and $6 per
ton of sulfur, for neutralization facilities having daily H2S04 capacities
of one hundred tons, 350 tons and 1000 tons, respectively. This would add
about $5, $3 and $2 per ton of 112804 to the acid production costs, respectively.
American Smelting and Refining Company (ASARCO) presented observations
from laboratory neutralization of sulfuric acid with milled limestone having
various fineness of grind. A "wet process" was used in one set of experiments
where the limestone was reacted with dilute sulfuric acid (one hundred grams
U2S04 per liter). A "dry process" was used in the other experiments, where
the limestone was reacted with concentrated sulfuric acid. For one limestone,
with the grind ninety-five percent through 200 mesh, in the wet process,
slurry pH of 6.5 was produced in thirty minutes with only seven percent excess
limestone. For the same limestone and grind, in the dry process, leachate
pH 6.5 was produced in sixty minutes with only three percent excess limestone.
For coarser grinds, more excess limestone or more reaction time was required
to produce pH 6.5.
The extent of solubillzatlon of calcium and magnesium was also observed
in the ASARCO experiments. ASARCO expressed concern regarding the potential
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hazards involved in putting out on dumps, subject to rainfall, vast quantities
of waste material containing tremendous amounts of soluble Epsom salts.
An obvious drawback of the slurry process discussed in this report is the
need for gypsum disposal ponds. For example, the gypsum from neutralization
of 350 tons of H2S04 daily would annually cover seven acres with a deposit
about twenty feet deep.
This leads to consideration of alternative neutralization processes
accommodating the evolution of reaction heat and C02 to produce dry gypsum or
perhaps the more useful less hydrated calcium sulfate. Suggestions regarding
process alternatives are included in the recommendations. Bases for conceptual
design of such alternative processes do not appear in the literature reviewed,
but the dry process experiments by ASARCO are pertinent.
Deposits of the relatively firm cake produced by the ASARCO dry process
would be more easily protected from rainfall than filled settling ponds. In
view of the neutralization of concentrated sulfuric acid in one hour using
little excess limestone, this process alternative appears quite promising.
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SECTION III - RECOMMENDATIONS
A. APPLICATION OF LIMESTONE NEUTRALIZATION
Because of the associated environmental problems presented by limesLw.s
quarrying, transportation, and grinding, and by the gypsum disposal ponds, it
is recommended that the process discussed in this report be considered for
short range application to limited situations. This process appears ideal for
the remotely located smelter which already has an abatement acid plant, pro-
vided there is a ready source of limestone. The remote location increases the
difficulty of selling the acid during unfavorable market periods. On the other
hand, the remote location minimizes the environmental impact of the limestone
operations and the gypsum disposal ponds. Many of the remotely located smelters
are in arid regions where covering filled ponds would be unnecessary.
The applicability of limestone neutralization of sulfuric acid would be
significantly broadened by development of alternative processes producing firm
waste instead of fluid gypsum sludge.
B. PROCESS DEVELOPMENT
It is recommended that the following experimental work be done to confirm
the workability of the slurry process and to improve the basis for final design
of specific facilities. This work should simulate use of limestone having high
contents of magnesium and chlorides, expected to produce the most troublesome
conditions.
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1. Confirm Che thermal balance and determine the reaction rate by
laboratory experimentation, including measurement of C(>2 evolution.
2. Using pilot plant equipment, as proposed by ASARCO, determine the
excess, if any, of limestone required, and determine the minimum grinding of
the limestone influencing the selection of materials of construction for the
slurry line to the gypsum settling pond.
3. Determine by actual trial the limitations on reaction conditions
precipitating gypsum which will settle suitably in the disposal pond.
4. In connection with the gypsum precipitation work, determine the
gypsum disposal pond volumetric requirements.
5. Determine whether significant amounts of 803 are evolved with the
(X>2 under the reaction conditions producing a suitable gypsum precipitate.
C. PROCESS ALTERNATIVES
It is recommended that the following process alternatives be considered
to gain the advantages of producing firm waste instead of fluid gypsum sludge.
Some of the experimental work on other pollution abatement processes may have
a bearing on these alternatives.
1. Filter or Centrifuge with Slurry Process
Depending on the nature of the gypsum precipitate found in the
development of the slurry process, it may prove feasible to employ filters or
centrifuges in the slurry process to produce a firm gypsum cake facilitating
disposal. If necessary, the slurry might be held in a cooling pond before
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being filtered or centrifuged. It seems noteworthy that the Chlyoda Thoroughbred
101 Flue Gas Desulfurization Process uses centrifuges to recover gypsum from
slurries*
2. Paste Process
Extending the technique of the ASARCO dry process experiments, feed
concentrated sulfuric acid and milled limestone into a continuous kneader
mixer, with enough water to produce the desired temperature by evaporation of
the excess water. The mixer discharges the paste into a rotating drum pro-
viding adequate residence time and discharging a firm gypsum waste. The C02,
water, air and any SO^ evolved are vented from the mixer and drum to an
agitated tank of limestone slurry or lime slurry. Slurry is drawn from this
tank to provide the required water in the kneader mixer.
This process would be similar in some respects to the process for
producing hydrofluoric acid, in which milled fluorspar is mixed with sulfuric
acid and the resulting paste heated in a rotary kiln to evaporate the HF,
leaving dry gypsum byproduct.
3. Sulfur Trioxide Limestone Process
Convert the sulfur content of the acid plant feed gas to 503 and,
instead of absorbing the 803 in water, pass the resulting gas through fluid-
ized beds of milled limestone arranged for countercurrent flow, the excess
water and CC^ evolved joining the spent gas, and the dry gypsum being
discharged from the last bed.
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4. Sulfur Trioxide Quicklime Process
i
Convert the sulfur content of the acid plant feed gas to 803 and
Instead of absorbing the 803 In water, pass the resulting gas through fluid-
izing beds of quicklime, arranged for countercurrent flow, the excess water
joining the spent gas and the anhydrite being discharged from the last bed.
In experiments to determine the feasibility of this process,
observation should be made of the extent to which the 803 is decomposed to
S02 on particle surfaces overheated by the highly exothermic .reaction. Study
of this process might well be started following the procedures used in study-
ing the reaction of 802 and CaO, as described in December 1971,.Environmental
Science & Technology pages 1191-1195 "Reactions of Gaseous Pollutants with
Solids I. Infra Red Study of the Sorption of 802 on Ca°" hy M. J. D. Low,
Arthur J. Goodsel and Nobotsune Takezawa (Apendix D, Item 35).
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SECTION IV - DISCUSSION
A. PROPOSED NEUTRALIZATION PROCESS
In the process discussed In this report, abatement derived sulfuric &~f»l
is neutralized with milled limestone in an aqueous slurry, and the resulting
gypsum is deposited in a settling pond. Supernatant from the gypsum disposal
pond is used to slurry the limestone. The principal reactions include the
following:
H2S04 + CaC03 -I- H20 — * CaSO^ 2H20 + C02 + 26,500 calories per
gram formula.
H2SC>4 + Mg(X>3 — >MgS04 -I- H20 + (X>2 -I- 27,900 calories per gram formula.
The conceptual design of this process is shown in the flow diagram pre-
sented in Appendix A. Hilled limestone is slurried with supernatant overflowing
from the gypsum settling pond. The limestone slurry is pumped to the neutral-
ization tank, where the sulfuric acid is added. The C02 evolved is vented from
the neutralizer through the limestone slurry tank, to catch SOj vapors which
may be carried by the €02 .
The neutral slurry is pumped from the neutralizer to the gypsum settling
pond. The reaction heat is dissipated by evaporation of water from the pond.
The cold supernatant overflowing from the pond is diluted with water except as
rainfall makes up for evaporation and for the water left in the gypsum sludge
deposited in the pond.
The high magnesium content of the limestone in the example shown with the
flow diagram in Appendix A results in saturation of the supernatant with
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magnesium sulfate. The effects of this are mentioned later in this discussion.
B. PARALLEL PROCESS TECHNOLOGY
As no significant use has been made of this process in the past, it is
necessary to base the conceptual design for neutralization of sulfuric acid
with limestone on the technology of analogous chemistry commercially practiced.
Two processes present promising parallels. One of these is the reaction of
sulfuric acid with fluorspar to produce hydrofluoric acid and gypsum. The
other is the reaction of sulfuric acid and calcium phosphate to produce
phosphoric acid and gypsum.
1. Hydrofluoric Acid (HF) Technology
The HF technology is attractive because the byproduct gypsum is
dry. A major point of similarity to sulfuric acid/limestone neutralization
is found in the volatility of the HF and 2. On the other hand, a significant
difference is found in the heat balance.
In the HF process, after the sulfuric acid and milled fluorspar are
kneaded together, it is necessary to heat the mixture to vaporize the HF,
leaving the dry gypsum residue.
The reaction of sulfuric acid with limestone is highly exothermic,
producing far more heat than that required to vaporize the O>2. The mixture
of large quantities of concentrated sulfuric acid and limestone without cooling
might produce local high temperatures, thus vaporizing 803. Therefore, the
equipment requirements for mixing sulfuric acid and limestone may be quite
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different from those for mixing sulfuric acid and fluorspar. Hence It appears
that the HF technology Is not, at present, a useful basis for the conceptual
design for sulfuric acid limestone neutralization.
Nevertheless, It may be worthwhile to continue the experimental
work, pertaining to this process, begun by American Smelting and Refining Company
(ASARCO) to gain the advantages of producing firm waste from neutralization of
sulfuric acid and limestone. This is among the process alternatives recommended
for further study. The ASARCO data are reviewed in another part of this
discussion.
2. Wet Phosphoric Acid Technology
The conceptual design for the slurry process discussed in this report
is based largely on the parallels found in wet phosphoric acid technology. In
the typical wet phosphoric acid process, sulfuric acid and calcium phosphate
react to form phosphoric acid and gypsum. The gypsum is filtered from the
phosphoric acid solution. The gypsum is washed with water on the filter to
increase recovery of acid. The wash filtrate is used as makeup in the reaction.
A principal requirement is to provide conditions producing gypsum suitable for
filtering and washing.
The reaction is exothermic, and heat removal is required. Water
cooling coils are quickly fouled by gypsum scaling. Heat is removed by
evaporation of water, which offsets the dilution of the acid by the gypsum
filter wash water. The cooling may be by flash evaporation under vacuum.
The vacuum flash evaporators are operated for months between shutdowns to wash
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out the gypsum scale. The reaction mixture may be cooled and the water may be
evaporated by injecting air into the reacting mixture. This is troublesome,
despite special devices used to minimize plugging and corrosion.' The use of
air also increases the fume scrubbing requirements.
Troublesome foaming is caused by C<>2 evolution from carbonate
impurities in the calcium phosphate rock.
Chloride and fluoride impurities Increase the severe corrosion
problems inherent in the wet phosphoric acid process.
Byproduct use of the wet gypsum is seldom economical in the United
States. The usual practice is to reslurry the filter cake with supernatant
from a pond and to pump the slurry to a gypsum disposal pond. Dumping the
wet gypsum cake has rarely been advantageous.
3. Favorable Differences
Several of the differences from the wet phosphoric acid process result
in easier conditions for the sulfuric acid limestone neutralization process, as
follows.
As no salable product is being recovered from the limestone, it Is
not necessary to filter, wash, and reslurry the gypsum. Instead, the reaction
mixture may be pumped directly to the settling pond with minimal concern for
completion of the reaction and gypsum crystal growth. On the other hand, while
the slurry pipe to the settling pond may be carbon steel for the phosphoric
acid plant, more corrosion resistance may be required for the pipe carrying
incompletely reacted sulfuric acid and limestone slurry.
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Furthermore, although the gypsum precipitated in the limestone
neutralization is not to be filtered, it must settle suitably in the disposal
pond. This might prove to be equally as stringent a requirement as suitability
for filtering.
Although the C(>2 evolution from the limestone presents a potentially
greater foaming problem than the carbonate impurities in calcium phosphate
rock, this need not be faced in a vacuum flash evaporative cooler. Whereas the
phosphoric acid reaction is cooled by recirculating the reaction slurry through
the flash evaporator, the limestone neutralization may be cooled by dilution
with supernatant from the gypsum settling pond.
The corrosion conditions are expected to be much less severe with
the nearly neutral brine than with the phosphoric acid reaction mixture.
C. LIMESTONE COMPOSITION
The magnesium content of the limestone is expected to be a significant
variable in the slurry process discussed in this report. The effects of the
magnesium content result principally from the great solubility of magnesium
sulfate.
The material balance shown with the flow diagram presented in Appendix A
is based on a magnesium to calcium weight ratio of about 28 to 72 in the milled
limestone. This ratio was chosen to give an example In which the supernatant
would be saturated with magnesium sulfate. A higher magnesium content in the
limestone would result in depositing Epsom salts with the gypsum in pond sludge.
A lower magnesium content in the limestone would, of course, result in a lower
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magnesium sulfate concentration in the supernatant.
The magnesium contents of limestones vary widely. The two limestones used
in the ASARCO experiments contained 0.5 percent and 2.0 percent magnesium by
weight, in contrast to the ten weight percent magnesium content of the lime-
stone in the flow diagram presented in Appendix A. As low magnesium limestone
is required for cement manufacture, it might prove advantageous to use high
magnesium limestone for neutralization of abatement derived sulfuric acid.
Furthermore, valuable byproducts might eventually be derived from the rather
pure magnesium sulfate solution produced.
The magnesium sulfate concentration in the supernatant, and hence in the
limestone slurry, is expected to affect the reaction with sulfuric acid. The
effects may include neutralization rate, C02 evolution, S03 evolution, foaming,
and gypsum crystallization. These effects should be observed in the experi-
mental work recommended in this report.
Other effects of the magnesium sulfate concentration in the supernatant
include specific gravity, viscosity, specific heat, and water vapor pressure,
all of which affect pump performance, operating temperature*, and evaporation
from the pond.
Although limestones rarely contain significant amounts of chlorides, the
chloride content of the limestone should be observed because of the adverse
corrosion effects which chlorides would have on stainless steels used in the
sulfuric acid neutralization system.
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D. SLUDGE POND MANAGEMENT
For the typical limestone slurry neutralization facility, it appears
advisable to build one sludge pond each year, each pond having capacity for
one year. Fond costs are thus postponed until the need is clear. It is
expected that a time may be found each year when pond construction costs will
be minimum. Depending on what part of the acid is neutralized, it might even
prove satisfactory to skip a year of pond building. This method of sludge
pond management is reflected in the process economics presented later in this
discussion.
Another benefit of ponds of annual size is accommodation of rainfall.
The annual water requirements for the sludge and the annual evaporation from
the pond are equivalent to about 200 inches of rainfall on one annual pond.
If filled ponds were left exposed to rainfall with the runoff collected in
the pond currently in use, the process would require annually the equivalent
of one hundred inches of rainfall on two annual ponds, fifty inches on four
ponds, twenty inches on ten annual ponds, and so on. Depending on the annual
rainfall at the limestone slurry neutralization facility, this would limit
the number of annual ponds which could be left exposed. Additional annual
ponds would have to be covered so rain falling on them could be diverted from
the other ponds without environmental pollution. Four annual ponds could be
left uncovered in all but the wettest regions of the United States, such as
the Gulf Coast.
Instead of annual ponds, some pond cost saving might be achieved by construc-
tion of larger ponds depending on the number of years of acid neutralization
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foreseen, and on the pond area limits related to the expected rainfall.
The water balance and pond requirements are obviously affected by variation
in sludge compaction. The ease of covering filled ponds and the feasibility
of building dikes of dredged sludge depends on the stiffness of the sludge.
In the example shown in Appendix A, there are seven pounds of gypsum and lime-
stone per gallon of sludge, that is, 52 pounds per cubic foot, about three
quarters of the density of loose, powdered gypsum. While this is a reasonable
assumption, the composition and volume of the sludge remain key factors to be
determined in the experimental work recommended in this report.
The water balance is also affected by the concentration of the sulfuric
acid. In the example shown in Appendix A, the H2S(>4 concentration is 93 weight
percent. Not only is more water introduced with acid of lower concentration,
but also there is less heat of reaction, so less water is evaporated from the
pond.
E. PROCESS ECONOMICS
The economics of the limestone slurry neutralization process, expressed
in 1972 dollars, are summarized in Appendix B, pages 25, 26 and 27, for daily
H2S04 capacities of one hundred tons, 350 tons and 1000 tons.
The costs for limestone grinding facilities are based on Information
presented in Sulfur Oxide Removal From Power Plant-Stack Gas; Conceptual
Design and Cost Study. Sorption By Limestone or Lime: Drv Process by
Tennessee Valley Authority, 1968 (Appendix D, Item 23).
In addition to the grinding facilities, the grinding and neutralization
costs include the equipment indicated on the flow diagram in Appendix A, but
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of proportionately leaser size for daily capacities less than 1000 tons
While land for ten annual ponds is included in the investment costs,
only the first annual gypsum disposal pond is included. In the operating
costs, therefore, the pond is depreciated entirely in the year when all acid
is neutralized but at ten percent annually when no acid Is neutralized. No
i
additional allowance is included for covering ponds from rainfall. It; might
prove feasible to cover filled ponds with soil from construction of new ponds.
The costs estimated for the ponds are based on the following construction,
typical of the requirements in many situations to minimize leakage of sulfate
solutions to groundwater. The dikes forming the ponds are constructed of soil
excavated from the Interior area to a level Just above the groundwater table.
The bottoms of the ponds and inside slopes of the dikes are covered with a six
inch thick layer composed of selected excavated material into which bentonite
has been mixed. Another four inch to six inch layer of excavated material is
placed on top of the bentonite-treated layer. The outside faces and tops of
the dikes are finished with a layer of topsoll. The supernatant collection
structure is constructed opposite the slurry inlet, and includes an adjustable
weir gate and a sump for the supernatant pump. Costs of ponds may be
considerably different for ponds of different construction permitted and/or
required by topography, soil conditions, climate, and other site factors.
Instead of annual ponds, some pond cost saving might be achieved by
construction of larger ponds, depending on the number of years of acid
neutralization foreseen, and on the pond area limits related to the expected
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rainfall. The initial cost for such a pond would not have the one year write-off
appropriate for an annual pond, but would have a longer amortization. For a
pond constructed over a number of years, with dikes built of gypsum periodically
dredged from the bottom, the dredging coats would be added to the amortization
of the initial cost.
Acid storage facilities are expected to be adequate in the acid plant,
so none are included in the neutralization facilities, nor is standby spare
equipment included. With adequate acid storage available, a brief interrup-
tion in the neutralization operation would not significantly affect the
operation of the pollution abatement acid plant, or its source. Two
neutralization tanks are the only dual equipment for the 1000 tons H2S04 daily
capacity. For facilities of greater capacity, dual ball mills might be required
for limestone grinding.
The operating costs for the neutralization facilities are presented per
ton H2S04 for consideration with acid prices and per ton sulfur for consider-
ation with sulfur emission abatement costs. There being no operating plant
using the subject process, the operating costs are based on estimated performance,
not actual experience. The allowance for maintenance, annually five percent
of investment, is typical for facilities operating similar equipment. The
limestone grinding facilities are expected to require more than half of the
operating labor attention, the balance being required for attendance of the
neutralization and pond operations. About three quarters of the power require-
ment is for the limestone grinding mill motor. The delivered cost of limestone,
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$3 per ton, ±B based on information presented in the 1968 TVA study
(Appendix D, Item 23), with escalation to 1972 dollars.
No cost has been assigned to water required during initial operation
and at other times when there is not enough supernatant available from
the pond. Some circumstances might require consideration of this cost,
especially the dry seasons in arid regions.
Limestone slurry neutralization costs are presented In Appendix B,
page 28, with acid plant operating costs for daily 112804 capacity of 350
tons based (for example) on abatement of smelter offgas sulfur. Acid
plant operating costs are shown for S02 concentrations of two, six, and
twelve mole percent in the smelter offgas.
The acid plant operating costs are based on information presented in
Systems Study For Control of Emissions. Primary Non Ferrous Smelting Industry
by Arthur G. McKee & Company, June 1969 (Appendix D, Item 29). These costs
reflect the need for preheating the two mole percent SC>2 smelter offgas for
conversion to SOj.
F. AMERICAN SMELTING AND REFIHIKG COMPANY DATA
American Smelting and Refining Company presented observations from
laboratory neutralization of sulfurlc acid with milled limestone having
various fineness of grind. In one set of experiments a "wet process" was
used, in another a "dry process" was used. Of the two, the wet process is
more similar to the process discussed in this report.
19
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.ESSES RESEAKCH. INC
INDUSTRIAL PLANNING AND RESEAKCH
The ASARCO data are shown in Appendix C. The figurea have been redrawn
to include the supplementary information from ASARCO.
In the wet process experiments, dilute sulfuric acid (one hundred grams
H2S04 Per liter) was reacted with limestone for a period of time, and the
slurry pH was observed. For one limestone, about 107 percent of the etol-
chiometrlc ratio of limestone to acid produced slurry pH 6.5 in thirty minutes
with the grind ninety-five percent through 200 mesh, and in 6.5 hours with the
grind thirty-nine percent through 200 mesh. For this limestone, with the
grind thirty-nine percent through 200 mesh, about 151 percent of the stolchi-
onetric ratio of limestone to acid produced slurry pH 6.5 in thirty minutes.
For the other limestone, with the grind sixty-one percent through 200 mesh,
about 144 percent of the stoichiometric ratio of limestone to acid produced
slurry pH 6.5 in thirty minutes.
In the dry process experiments, concentrated sulfuric acid was reacted
with limestone for one hour, the cake was then leached with water, and the
pH of the resulting solution was observed. For one limestone, with the
grinds ninety-five percent and \hirty-nine percent through 200 mesh, about
103 percent and 197 percent, respectively, of the stoichiomecric ratio of
limestone to acid produced pH 6.5. For the other limestone, with the grinds
ninety-one percent and sixty-one percent through 200 mesh, about 122 percent
and 160 percent, respectively, of the stoichiometric ratio of limestone to
acid produced pH 6.5.
20
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PROCESSES RESEARCH, INC.
INDUSTRIAL PLANNING AND RESEARCH
The extent of solubilization of calcium and magnesium was also observed
in these experiments. Although the two limestones contained only 0.5 percent
and 2.0 percent magnesium, ASARCO expressed concern regarding the potential
hazards Involved in putting out on dumps, subject to rainfall, vast quantities
of waste material containing tremendous amounts of soluble Epsom salts.
21
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PROCESSES RE SEARCH,.INC.
INDUSTRIAL PLANNING AND RESEARCH
APPENDIX A - PROCESS PLOW DIAGRAM
22
-------
109
lob
PROCESSES RESEARCH, INC. me No
Local ion
INDUSTRIAL PLANNING
AND RESEARCH Chedtd by
_She«l No.A;
Date
NEUTRALIZATION
CINCINNATI
NEW YORK Co»p.led by
COL C 0$
44-9 T/D
T/P
T/P
6.25 T/P
334 T/P
MILLEP LIME^T
-------
PROCESSES RESEARCH, INC.
INDUSTRIAL PLANNING AND RESEARCH
APPENDIX B - PROCESS ECONOMICS
24
-------
PROCESSES RESEARCH, INC.
INDUSTRIAL PLANNING AND RESEARCH
ECONOMICS OF LIMESTONE NEUTRALIZATION
FOR 100 TONS H2S04 DAILY
Investment
Grinding and Neutralization $600,000
Land for ,Ten Annual Ponds, $500 per Acre 15,000
Annual Gypsum Disposal Pond 160.000
Total Investment $775,000
All Acid No Acid
Daily Operating Cost Neutralized Neutralized
Interest, Taxes, and Insurance, Annually
7 percent of Investment $ 155 $ 155
Depreciation, Grinding and Neutralization,
Annually 10 percent of Investment 172 172
Depreciation, Annual Pond 457 46
Maintenance, with Overhead, Annually
5 percent of Investment 111
Labor, with Overhead, $7 per Hour 336
Power, 1.5 cents per Kwh 72
Limestone, delivered, $3 per Ton 426
Total Daily Operating Cost $1,729 $ 484
Incremental Operating Cost per Ton H2S04 $17.29 $ 4.84
Incremental Abatement Cost per Ton Sulfur $52.85 $14.80
Daily Sulfur Tonnage 33 33
25
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PROCESSES RESEARCH, INC.
INDUSTRIAL PLANNING AND RESEARCH
ECONOMICS OF LIMESTONE NEUTRALIZATION
FOR 350 TONS H2S04 DAILY
Investment
Grinding and Neutralization $1,160,000
Land for Ten Annual Ponds, $500 per Acre 45,000
Annual Gypsum Disposal Pond 325,000
Total Investment $1,530,000
All Acid No Acid
Daily Operating Cost Neutralized Neutralized
Interest, Taxes, and Insurance, Annually
7 percent of Investment $ 306 $ 306
Depreciation, Grinding and Neutralization,
Annually 10 percent of Investment 331 331
Depreciation, Annual Pond 928 93
Maintenance, with Overhead, Annually
5 percent of Investment 219 219
Labor, with Overhead, $7 per Hour 560
Power, 1.5 cents per Kwh 229
Limestone, delivered, $3 per Ton Ii494 1_
Total Daily Operating Cost $4,067 $ 949
Incremental Operating Cost per Ton H2S04 $11.63 $ 2.71
Incremental Abatement Cost per Ton Sulfur $35.60 $ 8-29
Daily Sulfur Tonnage
26
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PROCESSES RESEARCH, INC.
INDUSTRIAL PLANNING AND RESEARCH
ECONOMICS OF LIMESTONE NEUTRALIZATION
FOR 1,000 TONS H2SO* DAILY
Investment
Grinding and Neutralization $2,080,000
Land for Ten Annual Ponds, $500 per Acre 125,000
Annual Gypsum Disposal Pond 670,000
Total Investment $2,875,000
All Acid No Acid
Daily Operating Cost Neutralized Neutralized
Interest, Taxes, and Insurance, Annually
7 percent of Investment $ 575 $ 575
Depreciation, Grinding and Neutralization
Annually 10 percent of Investment 594 594
Depreciation, Annual Pond 1,915 192
Maintenance, with Overhead, Annually
5 percent of Investment
Labor, with Overhead, $7 per Hour
V*. __ • m ____»-_ »»_ _1_
411 411
L>aDor, witn weiueau, yi pci nwui. 700 -
Power, 1.5 cents per Kwh 512
Limestone, delivered, $3 per Ton 4,254 ^_
Total Daily Operating Cost $8,961 $1,772
Incremental Operating Cost per Ton I^SO^ $ 8.96 $ 1.77
Incremental Abatement Cost per Ton Sulfur $27.40 $ 5.41
Daily Sulfur Tonnage 327 327
27
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PROCESSES RESEARCH, INC.
INDUSTRIAL PLANNING AND RESEARCH
ECONOMICS OF LIMESTONE NEUTRALIZATION
FOR 350 TOWS H?SO& DAILY
Smelter Offgas Pollution
Abatement Coats
Acid Plant Operating Costs,
per Ton Sulfur
Neutralization Operating
Costs, per Ton Suflur
Total Abatement Costs,
per Ton Sulfur
2 Hole Percent
S02 In Smelter
Offgas
$ 78
36
$114
6 Mole Percent
S02 In Smelter
Offgaa
$ 33
36
$ 69
12 Mole Percent
S02 In Smelter
Offgas
$ 25
36
$ 61
Daily Sulfur Tonnage
114
114
114
28
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PROCESSES RESEARCH, INC,
INDUSTRIAL PLANNING AND RESEARCH
APPENDIX C'- AMERICAN SMELTING
AND REFINING COMPANY DATA
29
-------
£_5A_RCO AMERICAN SMELTING AND REFINING COMPANY
***~~^ CENTRAL RESEARCH LABORATORIES
SOUTH PLAIN PI ELD. N. J. 07080
WIUUH K IOC
«lltC*O* Of tISIMCN
VU, KUOITK
Mwoi^..iuu.nu.M March 13, 1972
«t. I. HOWf
•MUAUL •nu niuicit
Mr. Kornan Plaks, Chief
Industrial Process Section
Demonstration Projects Branch
Control Systems Division
Environmental Protection Agency
Research Triangle Park, H. C. $7711
Dear Mr. Plaks:
Your letter of February 7 has been received and I -wish to thank
you for the brief report on neutralization of abatement derived
sulfuric acid.
Our investigation of limerock neutralization has been strictly
of a laboratory nature v.lth the emphasis directed primarily at
determination of linerock requirements and the extent to which
calcium and magnesium are solubilized. Two different limerocks,
having the following analyses, have been employed in this study.
Limerock No. 1 Liraerock No. 2
CaO 47.3# CaO 48.20
MgO 0.9 MgO 3.3
FeO 0.4 FeO 0.4
SiOs 1.0 SiOa 4.5
Two methods of effecting neutralization have been examined. The
first of these, which in terms of possible future scale-up, nay
be considered similar to the first step of the wet process for
producing phosphoric acid, involved addition of ground limerock,
slowly v.lth continuous stirring, to a dilute sulfuric acid
solution (100 gm H.,S04/liter). Follo:-.-ing addition of the linerock
stirring v:as continued for 30 minutes and then zhe pH of the
resultant slurry was determined. From a number of such tests
involving differing limerock additions, a series of curves were
developed depicting slurry pH, -at the end of an essentially
constant reaction time, expressed as a function of liinercck
addition.
30
-------
Reproduced from
best available copy..
Mr. No man Plaks
- 2 -
March 13, 1972
The second method of neutralization, in terns of possible future
large scale- application, nay be considered similar to z'r.s den
method for producing superphosphate. Here a fixed vol^e of
concentrated sulfuric • acid was slowly added to a known -.-reight
of ground linerock. The acid-liaerocX mixture ••:as prepared in
a mortar ana lightly "worked" with a pestle as the acid -.as added.
Following mixing of acid ar.d lixerock, which required five to ttr>
minutes, the essentially dry product vas allowed to s^ir.d for an
hour, v:as sampled, and then leached with water. Measurement of
the pH of the" leach solution"gave an indication of the extent to
which neutralization was effected in the allocated rea=-icn time.
Leach solutions were also analyzed to determine soluble calcium
and magnesium.
For purposes of the discussion to follow, the two methods of
neutralization hereafter -..-ill "ce referred to sL-nply as -he wet
method and the dry method respectively. Fineness of grind of the
limerock was another variable examined in this laboratory investiga-
tion. Following is a tabulation of screen analyses of limerock used
in the neutralization study:
Limerock No. 1
Limerock "o. 2
Grind Ho. 1
+60 mesh 32.0Jo
-60+100 18.0
-100+200 11.0
-200 39.0
Grind Ho. 2
Grind No. 1
+100 mesh 1.0>» +60 mesh 7-0;»
-100+200 3.9 -60+100 7.6
-200+325 9.0 -100+200 24.3
-325 87.0 -200+325 15-*
-325 45-7
Grind Ko. 2
+100 mesh 2.C.I
-100+200 7.0
-200+325 11-3
-325 80.0
"Wet Process" Neutralization
Typical curves, deDicting slurry pH as a function of ILv.ercck addition,
are illustrated in"Figure No. 1. It is essential to reccsr.ize that
these curves do net depict the addition of an increasing -..-eight of lire-
rock to a single sample of sulfuric acid. Rather, to illustrate the
effect of the degree of grinding, each of the plotted pcir.vS represen-s
a test in vrhich the indicated weight of 11 ae rock was added ~o 300 nil cf
dilute sulfuric acid (100 ga H.,S04/liter) and allowed to react for a
period of 30 minutes. For example, from the. curves of Figure No. 1
•31
-------
-------
Mr. Norman Plaks - 3 - March 13, 1972
it may be estimated that 38 gms of the very finely ground limerock
would be required to reach a slurry pH of 6.5 v:hile 5^ gms of the
relatively coarsely ground limerock would be required to attain
this same pH. These weights correspond respectively to approximately
107£ and 15l£ of stoichioaetric. With an intermediate grind, i.e.
Limerock No. 2, Grind Ko. 1, approximately 1^5 of stoichioaietric
would be required to attain a slurry pH of 6.5.
Thus, it is evident that fineness of grind could be extremely importer
insofar as actual limerock recuirement for acid neutralization is
concerned. With increasing reaction time differences in limestone
requirement attributable to varying fineness of grind tend to decrease.
For example, with a 6.5 hour reaction tine rather than the 0.5 hour
reaction tine depicted in Figure lio. 1, the neutralization efficiency
of Grind No. 1 for Limerock No. 1 was essentially the same as that of
Grind No. 2 for Limerock No. 1 at the much shorter reaction time.
This is, of course, consistent with the frequently cited observation
that precipitation of calcium sulfate tends to "blind" the surface of,
at least, the coarser particles of limerock.
At this point in time we have not attempted to determine the optimum
degree of grind. Discounting, for the moment, the importance of such
factors as magnesium solubilization, optimum grind would, of course,
be dependent upon such cost related determinants as power cost for
grinding versus povrer cost for agitation, capital cost for grinding
equipment versus capital cost of reaction vessels, etc. It would
appear, however, that any attempt to determine optimum degree of
grind should be based on data derived by using somewhat larger scale
equipment, i.e. a small pilot plant, in order to obviate uncertainties
associated with direct scale-up from 'beaker tests.
Solubilization of calcium and magnesium is illustrated in Figures Uo. 2
and 3 where concentrations of calcium and magnesium are plotted as a
function of solution pH. As in Figure No. 1, each point on these
ring
generally increasing dissolution of magnesium as solution pH increases
over the range of approximately 1 to 7 in the case of the linercck of
lower MgO content and generally constant dissolution of magnesium with
increase in solution pH from approximately 1 to 7 for the linerock or"
higher KgO content.
Referring to Figure Uo. 3 it will be noted that in one test solution
pH was increased to a value'of 9.5» This was effected by the addition
of hydrated liae after the acid had been essentially neutralized by
limerock. As would be expected, magnesium solubility *:as sc~ev;hat
decreased at this higher pH.
33
-------
-------
u>
™
:•
•
™, ...
-•••• .
i«*
• *
•••
!::: :::S:K:
**••• » • • • . ..-.-. .,- -• - ."I,.. .. .-,,-,: .VI,- -.-.. =. •• '. '"... '.
-------
Mr. Nonnan ELaks - 4 - March 13, 1972
In a practical sense it is perhaps r.cre meaningful to -compare the
percentages of total magnesium solubilized v.lth the acid essentially
neutralized, i.e. at a solution pK of 6.5-7.0. With the llserock
more finely ground, 33-3-; j of the total magnesium was. solubilized
with final solution pH at 6.5-7-0 regardless of whether the acid was
neutralized with the linerock of higher (3.3-3) KsO content or the
liinerock of lower (0.9fj) MgO content. In neutralizing acid with the
very finely ground limestone of the higher MgO content and subsequently
increasing slurry pK to 9.5 through the addition of hydrated line, 2C,t
of the total nagnesiua remained in solution.
The degree of grind of the limerock also has a rather pronounced
effect on magnesium solubilization. For example, in neutralizing
acid with limerock of the lov:er IlgO content (reaction time being
constant at 30 minutes) 33£ of total magnesium in the linerock
appeared in the final neutral solution. However, sinceJihe actual
liraerock requirement for neutralization anounted to lO?,^ of stoi-
chiometric for the more finely ground material and 151£ of stcichio-
metric for the more coarsely ground aaterial, absolute solubiiization
of magnesium was 41$ greater in the case of the latter.
"Dry Process" neutralization
In the "dry process" neutralization tests limerocks, again differing
with respect to -both composition and grind, were employed. After
thorough"mixing of linerock and acid, each cake vas allowed to stand
for one hour and vas then leached in water. The soluble magnesium
contents, as well as the pH, of the resultant solutions were determined.
Solution pH is plotted in Figure Ho. 4 as a function of the weight of
limerock added to individual samples of acid and a?;ain, as in -v:et
neutralization," the efficiency with which the liaerock is utilized is
shown to be highly dependent upon fineness of grind. From the curves
it may be estimated that limerock requirements to effect neutralization,
i.e. to attain a pH of 6.5, for the four limerock samples are as
follows:
Limerock Grind Limerock Requirement, $ of
Stoichiometric
No. 1 No. 2 87.0£-325 mesh 103
No. 2 No. 2 80.0;»-325 " 122
No. 2 No. 1 45.7£-325 " 1°"0
No. 1 No. 1 39«0£-200 " 197
36
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-------
Mr. Norman Plaks March 13, 1972
Generally speajcing, a higher percentage of the magnesium content of
the limerock was rendered water soluble in "dry process" neutraliza-
tion as compared to "wet process" neutralization. The extent of
magnesium solubilization for the "dry process" tests are tabulated
as follows:
Limerock Grind Magnesium Solubilization, % cf
Total Magnesium
No. 1 No. 1 39.00-2QP mesh 41
No. 1 No. 2 87-0£-325- "; 68
No. 2 No. 1 45.7#-325 " 72
No. 2 No. 2 80.0^-325 " 77
As in those tests involving 'Vet process" neutralization, a greater
percentage of total magnesium in the limerock was solubilized as
fineness of grind increased* However, for both the linerock of low
magnesium content and the limerock of higher magnesium content,
absolute magnesium solubilization decreased with increasing fineness
of grind due to the fact that a lesser weight of limerock was required
to neutralize the acid in the case of the more finely ground material.
General
Insofar as the feasibility of limerock neutralization of abatement
acid is concerned, we share the concern of others in regard to potential
hazards involved in storage of vast quantities of waste material contain-
ing quite significant tonnages of soluble magnesium sulfate. Consider
for the moment, neutralization of 1COO tons of sulfuric acid/day with
limerock having a composition equivalent to that previously denoted
Limerock Z«o. 1, i.e. 0.9;» KzO. "Here there is the potential to produce
(depending, of course, upon the extent to wr.ich the magnesium were
solubilized) as much as 48.1 tens of soluble Spsom salts/day, equiva-
lent on a yearly basis to approximately 17*600 tons. Even if only .
20-305* 'of the magnesium were converted to the sulfate this would be,--in
my opinion, a tremendous amount of- soluble material to put out on a
dump subject to rainfall. I an, of course, well aware that your
organization, as well as other interested groups, recognize this problem
and that considerable attention has been and continues to be given tc
its solution.
We are pleased to be able to contrioute the data herein, limited thcug.-.
it is in comparison to the "total required before large scale neutraliza-
tion of abatement derived sulfuric acid can be effected with at least -
38
-------
Mr. Kosaan 71a&6 March 13, 1972
an approach to optimization of the several controlling parameters
and sone assurance of the safety of disposing of the waste aaterial.
We would appreciate having a copy of the current study when it is
completed.
Very truly yours,
Jr&nes M. Henderson
JMH/hb
-------
Match 31, 1972
fir. C. 8. tlaaelberger
Environmental Protection Agency
Office of Air Programs
Research Triangle Park
liorth Carolina 27711
Subject: Neutralization of Abatement Derived
Sulfuric Acid
Task Mo. 3, Contract Mo. 68-02-0242
ASARCO Data
Dear fir. Haeelberger:
Reference is made to American Smelting and Refining Company letter dated March 13,
1972, a copy of which vaa enclosed with your letter to ua dated Kerch 24, 1972.
In our review of the data, some questions have arlaen which you may vlah to discuss
with ASA&CO.
In Figure No. 1, regarding the "wot proceaa," a data point appears at 33 grama and
ptt 0.65 without Indication to which liaeroek tale point refere, except coincidence
of pfi of data points la Figure Ho. 2. It would be helpful to have confirmation by
ASABCO that the 33 grama pH 0.65 data point In Figure Ho. 1 im for Liaerock No. 1
Grind Ho. 1.
Also with regard to Figure No. 1, It would be helpful to have intonation from
ASARCO on the grans of Llaarock Ho. 1 Grind No. 1 added for pH 4.5.
In Figure No. 2 and Figure No. 3, regarding the aolubiliaetlon of calcium and
•agneeluD in the "wet process," the liaerock grinds and the amounts of llmerock
and acid are not indicated except by coincidence of pll of data points in Figure
Mo. 1. It weald be helpful to have confirmation by ASARCO that Figure No. 2
refers to Liaeroek No. 1 Grind No. 1 and that Figure Ho. 3 refers to Llmerock
Xo. 2 Grind Ho. 1.
The consents In the first paragraph on page 4 appear to refer, not to Figure No. 2
nor Figure No. 3, but to testa run on linerock "more finely ground" then Llmerock
No. 1 Grind Mo. 1 end Llmerock No. 2 Grind No. 1. It would be helpful to have con-
flroation by ASARCO that the first paragraph on page 4 refere to Liaeroek No. 1
Grind No. 2 and Liaeroek No. 2 Grind No. 2.
40
-------
Mr. C. S. Haselberger
Hwch 31, 1972
P«ge 2
Alw> regarding Llaeroctt. Ho. 2 Grind No. 2, it vould be helpful to havt information
from ASARCO an the gram of llmrock added to 300 ml of acid Cor pH 6.5 to 7.U at
30 minutes•
In Figure No. 4, regarding the "dry proceM," the left uost set of data paints
appear incorrectly designated Llmerock Ho. 1 Grind Ho. 1. It would be helpful to
have confirmation by ASARCO that Che left nest eet of data pointe in Figure :io. '*
actually refer to Llmerock Ho. 1 Grind Ho. 2.
Alee with regard to Figure No. 4, we preauae that about 280 ml of water wae used
in leaching each ceke. It vould be helpful to have confirnation of this by ASAKCO,
as thla bears on the significance of the pE observed.
Referring to the percentages of •agnesiun solubillsation for the "dry process"
tabulated in the firet paragraph on page 5, we presume that these data refer to
pH 6.5 solution*. It vould be helpful to have conflraetlon of this by ASARCO.
Very truly yours,
PROCESSES RESEARCH, IMC.
V. D. Beers
Project Manager
WDB/pa
cc: M. R. Jester
P. U. Semite
41
-------
April 4, 1972
Mr. G. S. Haselbcrger
Environmental Protection Agency
Office of Air Progress
Research Triangle Park
North Carolina 27711
Subject: Neutralization of Abatement Derived
Sulfurlc Acid
Tank No. 3, Contract No. 68-02-0242
A8ARCO Data
Dear Mr. Haaelberger:
An additional question has arisen In our review of the American Smelting and
Refining Company letter dated March 13, 1972.
In Figure No. 4 regarding the "dry process." 36 grama concentrated acid is said
to have been used for each cake. We had preeumed that this was 30 grams H2SO/
and 6 grams water, there having been 30 graaa 112804 used in each "vet process"
case. Six grams water would be the least adequate for the production of gypsura
(CaS04 • 2H20) by reacting 30 grams H2S04 with CaCOj.
The specific gravity of acid containing 30 graas U2S04 and 6 graas water would be
about 1.77, this being 83.3 percent b^SO^ This is not consistent with the
indication in Figure No. 4 that the concentrated acid had specific gravity 1.84.
Thirty-six graas of acid having specific gravity 1.84 would contain nore than
34 grams H2S04 and less than 2 grans water, this being, insufficient water for
production of gypsum by reacting 34 grama 1^804 with CaC03.
It would be helpful to have information from A.'iARCO regarding the proportions of
U2S°4 «nd water in the 36 grams concentrated acid used fc-r each cake In the "dry
process."
Very truly yours,
PROCESSES RESEARCH, L.iC.
W. D. Beers
Project itanager
WDB/pn
cc: M. R. Jester
P. W. Spaite
42
-------
LSARCO AMERICAN SMELTING AND REFINING COMPANY
CENTRAL RESEARCH LABORATORIES
SOUTH PLAIN FIELD. N. J. 07080
WIUIAM f. ROE
DHICTOt O» IKUICi
VM. KUORVK ArtT*'t inn T - -70
MANIOC*.KiNituiICSCMCN ApriJL J.J., j.'yld
H. I. HOWE
•MUOMbMWJ IUUICN
Mr. G. S. Has&lberger
Environmental Protection. Agency
Industrial Process Section
Demonstration Projects Branch
Control Systems Division
Research Triangle Park, North Carolina 27711
Dear Mr. Haselberger:
This is in reply to your letter of April 6, your handwritten
memorandum of the same date and the attachments dated March 31
and April 4 respectively in which Mr. W. D. Beers, Project Manager
for Process Research,. Inc. raises a number of questions relative
to data included in my letter of March 13 to your Mr. Norman Plaks.
Answers to the several questions of Mr. Beers follow:
A. With reference to Mr. Beers letter of March 31, 1972-
(1) As surmised by Mr. Beers, the data point appearing in
Figure Mo. 1 attached to my letter of March 13, correspond-
ing to a pH of 0.65 and a limerock addition of 33 grans
is, in fact, for Limerock No. 1, Grind No. 1. I should
have extended the curve for this particular limerock to
the lower pH value.
(2) All available data points are indicated in Figure No. 1.
At this time, the grams of Limerock No. 1, Grind No. 1
required to yield a solution pH of 4.5 can only be
estimated by interpolation.
(3) Figure No. 2 does represent data pertaining to use of
Limerock No. 1, Grind No. 1. The two data points
corresponding to a solution pH of 4.5 represent a reaction
time of 50 minutes rather than 30 minutes and, therefore,
were incorrectly included in this plot. Figure No. 3
-------
Mr. G. S. Haselberger - 2 - April 11, 1972
(5) I regret any chance Implication that each of the four
limerock samples was used in both "wet and dry process"
neutralization tests for this is not the case. Only
three limerock samples were employed in the "wet process"
tests, as indicated in.Figure No. 1.
(6) Mr. Beers is correct in that the left most set of data
points in Figure Ho. 4 should have been designated Lime-
rock No. 1, Grind No. 2.
(7) As will be noted in Figure No, 4 of my letter of March 13,
the amount of limerock actually used in each of the
several "dry process" neutralization tests illustrated
varied considerably. Similarly, the amount of water
used in leaching of the cakes was varied so as to maintain
an approximately equivalent liquid to solids ratio. Actual
water used in the leaches ranged from 330 ml to 650 ml.
(8) The comments In the first paragraph of page 5 relative to
magnesium sorubilization do refer only to those dry process
neutralization tests in which sufficient limerock was
added to neutralize the acid , yielding leach solutions
having a pH of 6.5 to 7.2, i.e. corresponding to the upper-
most point on each of the curves of Figure No. 4.
B. With reference to Mr. Beers letter of April 4 -
(1) As indicated, 36 grams of concentrated sulfuric acid
(sp. gr. of 1.84) was used in each of the "dry process1
tests. I will concede that this acid provides insufficient
water to form CaS04*2HaO.
Very truly yours,
t
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PKOC-.ESSES RESEARCH. INC,
INDUSTRIAL PLANNING AND RESEARCH
APPENDIX D - BIBLIOGRAPHY
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PROCESSES RESEARCH. INC*
INDUSTRIAL PLAKNIXG AND RESEARCH
1. 1933 International Critical Tables of Numerical Data by Clarence J. West
(Compiler).
Vol. 3 pages 292, 295, 324 and 325 "Vapor-Pressure Lowering" and "Boiling -
Point Elevations."
Vol. 4 page 349 "Strong Electrolytes in Water."
Vol. 7 pages 313, 314, 340 and 341 "Solubility - Slightly Soluble Salts."
2. October 1944 Chemical and Metallurgical Engineering Vol.51 No. 10 pages 124
and 125 "Up-Flow Neutralization of Acid Wastes" by Harry W. Gehm.
I
3. January 20, 1949 The Iron Age Vol. 163 No. 3 pages 49-53 "Dry Lime Treatment
of Waste Pickle Liquor" by C. J. Lewis.
4. June 1949 Rock Products Vol. 52 No. 6 pages 117-119, 149, 150 "Some Practical
Suggestions On Waste Acid Treatment" by C. J. Lewis.
5. January 1952 Chemical Engineering Vol. 59 No. 1 pages 250 and 251 "Shortage
Glamorizes Gypsum."
6. June 1952 Chemical Engineering Vol. 59 No. 6 pages 242-245 "Ammonium Sulphate
From Gypsum."
7. October 1952 Ohio River Valley Water Sanitation Commission pages 13, 15, 17-19,
21, 23, and 28-32 "Disposal of Spent Sulfate Pickling Solutions" R. D. Hoak.
8. 1953 Illinois State Geological Survey Report of Investigation No. 164 pages 99,
100 and 102 "Water - Soluble Salts in Limestones and Dolomites" J. E. Lamar
and R. S. Shrode.
9. November 1955 Chemical Engineering Vol. 62 No. 11 pages 270-273 "Dicalcium
Phosphate."
10. July 1956 Sewage and Industrial Wastes Vol. 28 No. 7 pages 872-882 "Control
of Sludge Volumes Following Lime Neutralization of Acid Wastes" by S. D.
Faust, H. E. Orford, and W. A. Parsons.
11. 1957 Disposal of Industrial Waste Materials Conference pages 113-118 "Disposal
of Waste Acid with Special Reference to Waste Sulphuric Acid" by James T.
Richmond.
12. 1958 Seidelles-Solubilitiea, Inorganic and Metal-Organic Compounds D. Van
Nostrand Company Inc. Vol. 1, 4th Ed. pages 459, 471, 660-663, 673 and 674
plus Vol. 2 (1965) pages 524-527 by William F. Linke.
13. 1958 Proceedings. 13th Industrial Wastes Conference Purdue University pages
270-285 "Sludge Characteristics Resulting From Lime Neutralization of Dilute
Sulfuric Acid Wastes" by S. D. Faust.
46
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PROCESSES RESEARCH. INC.
IVDUSTRIAL PLANNING AND RESEARCH
14. 1959 ACS Monograph No. 144 (Reinhold Publishing Corporation) Manufacture of
Sulfuric Acid by Werner W. Duecker and James R. West pages 434, 440 and 441.
15. May 30, 1960 Chemical Engineering Vol. 67 No. 11 pages 87-92 "In Waste
Treatment Know Your Chemicals, Save Money" by H. L. Jacobs.
16. April 30, 1962 Chemical Engineering Vol. 69 No. 9 pages 94-96 "Hydrofluoric
Acid Process Gives New Role to Kneader" by N. P. Chopey.
17. May 27, 1963 Chemical Engineering Vol. 70 No. 11 pages 100-102 "IMG's New
Plant Shows Off Latest H3PO& Know-How" by Charles R. Banford.
18. September 15, 1964 U. S. Patent 3.148,948 "Cooling and Defearning Phosphoric
Acid Slurries" by William A. Lutz.
19. December 21, 1964 Chemical Engineering Vol. 71 No. 26 pages 34-36 "Concen-
trated Phosphoric Acid Again in Limelight."
20. Encyclopedia of Chemical Technology second edition (Interscience Publishers)
R. E. Kirk and D. F. Othmer editors.
Vol. 4 (1964) pages 14-27 "Calcium Sulfate."
Vol. 9 (1966) pages 86-96, "Phosphoric Acid."
Vol. 12 (1967) pages 414-427 "Lime and Limestone" and pages 731, 732 and 734
"Magnesium Sulfate."
Vol. 16 (1968) pages 712-720 "Acid Pulping."
Vol. 19 (1969) page 411 "Sulfurous Acid."
21. 1965 Chemical Treatment of Sewage and Industrial Wastes. .National Lime
Association pages 48-72, 79-85, 114-117 by William A. Parsons.
22. March 20, 1967 Chemical and Engineering News Vol. 45 No. 12 pages 54-58
"Fertilizer needs spur wet-process phosphoric."
23. 1968 Conceptual Design and Cost Study for the National Center for Air Pollution
Control Sulfur Oxide Removal From Power Plant Stack Gas. Sorptlon By Limestone
or Lime; Dry Process by Tennessee Valley Authority.
24. 1968 Phosphoric Acid (Marcel-Dekker Inc.) edited by A. V. Slack pages 29-37,
168-189, 215-217, 226-231 and 505-510.
25. March 26, 1968 U. S. Patent 3.375.066 "Process for the Continuous Production
of Gypsum and Iron Oxide from Waste Sulfuric Acid Pickle Liquor and a Calcium
Compound" by Keiichi Murakami etal.
26. August 30, 1968 Summary Report Battelle Memorial Institute "Investigation of
the Reactivity of Limestone and Dolomite for Capturing S02 from Flue Gas"
pages 19, A-l through A^4, and B-l by R. W. Coutant etal.
47
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PKOCDESSES RESEARCH, INC
INDUSTRIAL PLANNING AND RESEARCH
27. November 1968 Chemical Engineering Progress Vol. 64 No. 11, pages 59-65
"Economics of Sulfurlc Acid Manufacture" by J. M. Conner.
Pages 66-70 "Increasing Conversion Efficiency" by D. B. Burkhardt.
Pages 71-74 "Cost of Reducing Sulfur Dioxide Emissions" by J. G. Kronseder.
Pages 87-92 "Sulfurlc Acid from Calcium Sulfate" by T. D. Wheelock and D. R.
BoyIan.
28. March 31, 1969 Summary Report Battelle Memorial Institute "Screening of| Lime-
stones for S02 Reactivity" pages 1 and A-l by R. W. Coutant etal.
29. June 1969 Final Report Under Contract PH 86-65-85 for National Air Pollution
Control Administration Systems Study For Control of Emissions. Primary Non-
ferrous Smelting Industry by Arthur G. McKee & Company.
30. 1971 Farm Chemicals Handbook Meister Publishing Company "Plant Foods" pages
C85, C92, and C93 R. T. Meister editorial director.
31. March 1971 Minerals Processing Vol. 12 No. 3 pages 13-17 "Effect of Gypsum
Dust on the Environment" by J. S. Sheahan.
32. April 1971 Journal of the Air Pollution Control Association Vol. 21 No. 4
pages 185-194 "Control of Sulfur Oxide Emissions From Primary Copper, Lead
and Zinc Smelters - A Critical Review" by Konrad I. Semrau.
33. July 1971 Engineering and Mining Journal Vol. 172 No. 7 pages 61-71 "S02 laws
force U. S. copper smelters into industrial Russian roulette" by Lane White.
34. October 22, 1971 Final Report Task Order No. 18 Contract No. CPA70-1 for
Office of Air Programs Environmental Protection Agency Neutralization of
Abatement Derived Sulfuric Acid by Processes Research, Inc.
35. December 1971 Environmental Science and Technology Vol. 5 No. 12 pages 1191-
1195 "Reactions of Gaseous Pollutants with Solids. I. Infrared Study of
the Sorption of S02 on CaO" by M. J. D. Low, Arthur J. Goodsel, and Nobotsune
Takezawa.
36. December 1971 Engineering and Mining Journal Vol. 172 No. 12.
Pages 66-68 "Wet scrubbing of weak S02 gets a trial at new McGill pilot plant"
by Stan Dayton.
Pages 78-81 "Emissions controversy enters Phase II."
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RESEARCH. INC.
INJDLSTRIAL PLANNING AND RESEARCH
37. December 13, 1971 The Oil and Gas Journal Vol. 69 No. 50 page 39 "Desulfuriza-
tion projects mushroom In Japan."
38. February 1972 Chemical Engineering Progress Vol. 68 No. 2 pages 70-76 "The
Status of SOx Emission Limitations" by R. L. Duprey.
39. February 1972 Hydrocarbon Processing Vol. 51 No. 2 pages 24 and 25 "The
Chiyoda Thoroughbred 101 Flue Gas Desulfurization Process" advertisement.
40. March 1972 Environmental Science and Technology Vol. 6 No. 3 "Reactions of
Gaseous Pollutants with Solids. II. Infrared Study of Sorption of S02 on
MgO" by Arthur J. Goodsel, M. J. D. Low, and Nobotsune Takezawa.
41. March 1972 Engineering and Mining Journal Vol. 173 No. 3 pages 25 and 26
"ASARCO's new acid plant reduces S02 emissions from Hayden by 50%."
42. March 6, 1972 The Oil and Gas Journal Vol. 70 No. 10 page 42 "The Chiyoda
Thoroughbred 101 Flue Gas Desulfurization Process" advertisement.
43. April 1972 Environmental Science and Technology Vol. 6 No. 4 pages 350-360
"Properties of Carbonate Rocks Related to SO2 Reactivity" by Robert H.
Borgwardt and Richard D. Harvey.
44. April 1972 Hydrocarbon Processing Vol. 51 No. 4 pages 102-106 "Reduce Glaus
sulfur emissions" by Charles B. Barry.
45. April 1972 Power Vol. 116 No. 4 pages 56-60 "Air pollution control: Its
impact on the metal industries" by Rene'j. Bender.
46. April 1972 Engineering and Mining Journal Vol. 173 No. 4 page 9 "Economic
Impact Study sets high price on pollution control."
47. April 3, 1972 Chemical Engineering Vol. 79 No. 7 page 37 "The glutted sulfur
market and the Canadian aluminum industry."'
48. April 17, 1972 Chemical Engineering Vol. 79 No. 8 page 52 "The output of a
planned 600-ton/day acid plant will merely be neutralized."
49. May 15, 1972 Chemical Engineering Vol. 79 No. 11 page 57 "Leaching plant to
treat Arizona-mined copper."
50. May 17, 1972 Chemical Week Vol. 110 No. 20 pages 27 and 28 "Hydrometallurgy:
Copper's solution for pollution?"
51. June 1972 Environmental Science and Technology Vol. 6 No. 6 pages 518-522
"Removing heavy metals from waste water" by John G. Dean, Frank L. Bosqui
and Kenneth H. Lanouette.
52. June 1972 Hydrocarbon Processing Vol. 51 No. 6 page 15 "Claims sulfur removal
at 99.9% efficiency."
49
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