&EBA
United States
Environmental Protection
Agency
Industrial Environmental Research EPA-600/7-79-1 29
Laboratory May 1979
Cincinnati OH 45268
Research and Development
Antimony
Removal
Technology for
Mining Industry
Wastewaters
Interagency
Energy/Environment
R&D Program
Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development. U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/7-79-129
May 1979
ANTIMONY REMOVAL TECHNOLOGY
FOR MINING INDUSTRY WASTEWATERS
by
C. Leon Parker
Efim Livshits
Kathleen McKeon
Hittman Associates, Inc.
Columbia, MD 21045
Contract No. 68-03-2566
Project Officer
Roger C. Wilmoth
Resource Extraction and Handling Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Envi-
ronmental Research Laboratory, U.S. Environmental Protection
Agency, and approved for publication. Approval does not
signify that the contents necessarily reflect the views and
policies of the U.S. Environmental Protection Agency, nor
does mention of trade names or commercial products con-
stitute endorsement or recommendation for use.
ii
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FOREWORD
When energy and material resources are extracted, pro-
cessed, converted, and used, the related pollutional impacts
on our environment and even on our health often require that
new and increasingly more efficient pollution control methods
be used. The Industrial Environmental Research Laboratory -
Cincinnati (lERL-Ci) assists in developing and demonstrating
new and improved methodologies that will meet these needs both
efficiently and economically.
This report reviews literature on treatment technology for
removal of antimony from wastewaters in general and specifically
from mining wastewaters. The results indicate that in many cases
the antimony compounds are removed from mining wastes by simple
sedimentation because they are either insoluble or adsorbed
onto other insoluble materials. It appears the most promising
treatment technologies for those cases requiring further antimony
removal are starch xanthate and ion exchange. The information
contained herein forms the basis for directing additional research
and should be of interest to regulatory agencies, industry, and
universities involved in environmental programs for mining
industries. For further information on the subject, please
contact the Resource Extraction and Handling Division.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
ill
-------
ABSTRACT
This study was initiated with the overall objective of
assessing existing antimony removal technologies and evalu-
ating their potential for achieving minimum desired antimony
levels in mining industry wastewaters. In the course of the
assessment, both literature surveys and personal interviews
were conducted.
During the course of the study it was found that most
mines and mills reporting significant quantities of antimony
in their raw wastewater had approximately 0.1 to 0.2 mg/1
antimony remaining after tailings pond settling. This
reduction in antimony content without any chemical treatment
indicates that for most mines and mills the antimony-con-
taining wastewater components are in the form of suspended
solids and may be easily removed.
Information collected on antimony removal technologies
useful for removing soluble antimony from the wastewater of
the few mines and mills involved shows that sulfide pre-
cipitation technology cannot remove antimony to levels below
2.0 to 3.0 mg/1. Lime precipitation technology is not
capable of removal to levels below approximately 1.0 mg/1.
Neither of these commonly employed and recommended technolo-
gies, therefore, is suitable for achieving minimum desired
antimony levels. A minimum desired level of 0.5 mg/1 of
antimony was selected for this technology assessment based
on the effluent limitation recommended by the EPA BPCTCA
in antimony mines. There is currently no demonstrated tech-
nology for achieving this minimum desired antimony level.
Application of cost and technical feasibility analysis
to five potential antimony removal technologies (ion ex-
change, carbon adsorption, sodium borohydride reduction,
peat moss adsorption, and insoluble starch xanthate treat-
ment) indicates that ion exchange and insoluble starch
xanthate treatment are the most promising candidates for
further work. It is recommended that laboratory efforts be
initiated to develop a demonstrated antimony removal tech-
nology not only for mine and mill wastewaters but also for
smelters, battery manufacture, and other industries that
have high antimony concentrations in their wastewater.
iv
-------
This report was submitted in fulfillment of Contract
No. 68-03-2566 by Hittman Associates, Inc., under the spon-
sorship of the U.S. Environmental Protection Agency. This
effort was performed in the period from March 15, 1978, to
July 15, 1978.
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CONTENTS
Foreword iii
Abstract . . , , iv
Tables ..... viii
Acknowledgments ix
1. Introduction 1
2. Conclusions 2
3. Recommendations 4
4. Effluent Characteristics 5
Antimony occurrence in wastewaters .... 5
Reported data 5
Wasftewater treatment 14
5. Antimony Removal Technologies 18
Antimony chemistry 18
Sulfide precipitation 19
Lime precipitation 20
Ion exchange 21
Starch xanthate 24
Activated carbon 26
Peat moss 30
Sodium borohydride 31
6. Cost and Feasibility Analysis 36
S,utnmary 36
Influencing parameters 37
Feasibility methodologies 42
Technology analyses 45
References 57
vii
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TABLES
Number Page
1 Chemical Composition of Raw Wastewater Discharged
from Antimony Flotation Mill 7
2 Antimony Leach Plant Effluent and Tailings Pond
Effluent at the Sunshine Mine, 1975 8
3 Composition of Antimony-Containing Raw Wastewater
from Three Mines and Mills 10
4 Antimony Concentrations in Wastewaters from Primary
and Secondary Nonferrous Smelting (Exluding
Secondary Lead) 11
5 Raw Waste Characteristics - Secondary Lead
Smelters 12
6 Typical Effluent Analysis of a Paint Plant 13
7 Metallic Pollutants in a Dye House Wastewater Stream
Before and After Pilot Plant Peat Moss
Treatment 13
8 Suspended Solids and Total Antimony Removal by Mine
Tailings Pond 14
9 Monthly Average and Maximum Effluent Concentrations
(1975) Lime Treatment System, Secondary Lead
Plant 4131 16
10 Performance of Lime Treatment at Secondary Lead
Plant 4131 17
11 Activated Carbon Adsorption of Selective Metals . . 28
12 Percent Removal with Removal Technology
Combinations , 29
13 Treatment of Wastewaters Containing Heavy Metals . . 32
14 Summary of Process Applicability Estimates for
Antimony Removal 55
viii
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ACKNOWLEDGMENTS
The cooperation and assistance of Mr. Roger Wilmoth,
EPA Project Officer, and numerous individuals in EPA Regions
1, 6, 7, 8, 9, and 10 offices in arranging for contacts,
visits, and information collection with various mines is
gratefully acknowledged, as is the assistance provided by
the California Regional Quality Control Board and the
Nevada State Environmental Commission. Gratitude is also
expressed for the assistance provided by Mr. M. Jarrett, Mr.
R. Kirby and Ms. P. Williams of EPA Effluent Guidelines
Division, Washington, D.C.
Mining company representatives who not only supplied
pertinent information but also were kind enough to devote
additional time during mine visits are listed below:
Mr. Emil Fattu Mr. Walt Wide
Sunshine Mining Company Hecla Mining Company
Kellogg, Idaho Wallace, Idaho
Mr. George Lawrence Mr. Victor Botts
U.S. Antimony Corporation Placer Amax
Thompson Falls, Montana McDermitt, Nevada
Mr. George Brewer
Union Carbide Corporation
Bishop, California
In addition to the assistance provided in collecting
mine information, various individuals also contributed
significant information regarding treatment technologies.
These individuals included:
Mr. J. Dick, ICI Product Division, Wilmington,
Delaware
Mr. John Zschiegner - J&J Materials, Neptune City,
New Jersey
Mr. Allan Bessimer, Allan Bessimer Extract Sys-
tems, Manasquan, New Jersey
Mr. K. Jones, Mining Chemicals Group, Dow Cuemical
Co., Midland, Michigan
ix
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Mr. John Bell, Mogul Corporation, Chagrin Falls,
Ohio
0 Mr. Michael Cook, Ventron Corporation, Beverly,
Massachusetts
Mr. R. Wing, U.S. Department of Agriculture,
Northern Regional Research Laboratory, Peoria,
Illinois
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SECTION 1
INTRODUCTION
Antimony and its compounds have been designated by EPA
as toxic substances. Significant concentrations of antimony
have been observed in many discharges from the mining indus-
try, particularly the beneficiating processes. Current
technology involves antimony removal by lime precipitation;
however, this technique was questioned as to its ability to
reduce the antimony concentration to desired levels of less
than 0.5 mg/1.
The purpose of this study was to assess existing anti-
mony removal technologies and to evaluate the potentials of
these technologies for achieving minimum desired antimony
levels. A minimum desired level of 0.5 mg/1 of antimony was
selected for this technology assessment based on the effluent
limitations recommended by EPA BPCTCA in antimony mines (1).
The study entailed data collection on the chemistry and
solubility of antimony compounds and on reported treatment
technologies and their performance through published litera-
ture review and personal communications with the mining
industry, researchers, chemical suppliers, and wastewater
treatment equipment manufacturers.
In order to assess and evaluate the antimony removal
technologies, a methodology was developed to rate the var-
ious technologies as to probability of successful technical
application, cost impact, and overall feasibility. The
probability of successful technical application was deter-
mined from the combined products of probability ratings for:
(1) theoretical achievement of the desired antimony removal
level, (2) availability of materials and equipment, (3)
interference effects, and (4) estimated ability of research
and development efforts to overcome existing problems. Cost
impacts were estimated as a percentage of annual product(s)
value. The overall feasibility ratings were determined by
dividing the probability of successful technical application
by the cost impact value. The results of these ratings
provide direction for future research efforts.
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SECTION 2
CONCLUSIONS
As a result of this study, a number of conclusions were
reached that relate to antimony removal technology and its
performance as applied to mining industry wastewater. Most
of the mines and beneficiating mills which have measured
antimony in their raw effluent discharge wastewaters report
values that are significantly below 1 mg/1 antimony content,
even though the raw wastewater prior to tailings pond set-
tling often have much higher values. This dramatic decrease
in antimony content with no treatment other than a settling
pond indicates either that much of the reported total anti-
mony is in the form of settleable solids or that antimony
is adsorbed onto these solids and co-precipitates with
them.
For tne few mines where antimony is present in amounts
greater than 0.1 to 0.2 mg/1 in the discharged wastewater,
no known demonstrated removal technology for reducing it to
these levels has been found. In fact, very little work has
been reported on antimony removal below 0.5 mg/1 for any
technology, even at the laboratory level.
Lime precipitation removes antimony from wastewater to
the approximate level of 1 mg/1. In some cases, even lower
values have been reported, but these values are rarely below
0.5 to 0.7 mg/1. Sulfide precipitation which yields solu-
bility values of approximately 2 mg/1 and reported laboratory
results of 3.5 mg/1 may not be a practical technology for
antimony removal to the desired level of less than 0.5 mg/1.
Lime precipitation gives significantly lower residual antimony
contents than these reported sulfide precipitations.
Two other treatment technology areas not covered exten-
sively in this report are plant-specific technologies and
technologies which are primarily geared toward water recov-
ery. Plant-specific technologies include zero discharge,
recycle, reuse, and solar evaporation options which may be
applicable for specific locations and circumstances, but are
not generally usable. Technologies which have water recovery
-------
as their primary purpose include distillation, freeze dry-
ing, reverse osmosis, and electrodialysis. These tech-
nologies recover water but usually leave a concentrated
solution which requires further treatment or disposal.
In order to achieve antimony removals from mining
industry wastewatefs to levels below 0.5 mg/1, new treatment
technology needs to be developed and demonstrated. Results
of the cost and feasibility analysis of Section 6 of this
report indicate that ion exchange or insoluble starch xan-
thate treatment technologies are the most likely candidates
to achieve the desired antimony removal.
In order to keep ion-exchange and insoluble starch
xanthate removal technologies in perspective, however, it
should be emphasized that:
As removal technologies for antimony, both ion
exchange and insoluble starch xanthate are still
in the research laboratory stage, and only a small
amount of work has been done at this level.
Down to a level of approximately 1.0 mg/1 residual
antimony concentration, lime precipitation has
been widely demonstrated to be the most practical
and economical antimony removal technology.
Both ion exchange and insoluble starch xanthate
antimony removal technologies should be considered
as polishing operations to remove most of the last
mg/1 of antimony remaining after other treatment.
Other antimony removal or control technologies
such as zero discharge, recycle, water reuse,
process stream segregation, and solar evaporation
are often feasible in individual mining wastewater
situations. These options should be explored
prior to turning to the technologies evaluated in
this report.
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SECTION 3
RECOMMENDATIONS
Since antimony compounds are included on the EPA toxic
substances and priority pollutants lists and there is no
demonstrated technology for their removal below approximately
1 mg/1 residual concentration from mining, smelting, battery
production, paint, or other industrial wastewaters, it is
recommended that efforts be initiated to develop such
technology.
It is recommended that the technology development
include the following steps:
Soluble antimony-containing wastewaters which are
representative of those in the mining, smelting,
battery production, and other industries should be
selected. The total number of selected samples
should not be greater than six.
Laboratory screening of the samples should be made
to determine the chemical form and level of the
antimony present and its removal characteristics
for simple treatments such as lime and sulfide
precipitations.
Bench-scale screening experiments should be made
on the selected samples, using the findings of the
initial laboratory screening, to determine promising
antimony removal technologies. Ion exchange,
carbon adsorption, and insoluble starch xanthate
experiments should be included.
There should be a pilot plant scale-up of the
bench-scale results for one or more antimony-
containing wastewater streams. The pilot plant
could be located at an actual mine or other in-
dustrial site.
A full-scale treatment unit should be installed
and demonstrated.
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SECTION 4
EFFLUENT CHARACTERISTICS
ANTIMONY OCCURRENCE IN WASTEWATERS
Antimony is present in wastewaters of the metals min-
ing, primary and secondary nonferrous metals smelting, and
paint and surface coating manufacturing industries. It is
found in the effluents of dye houses, and in the coal-ash
basins of power plants. It may also appear in the waste-
nfwr^r f°V ? manu5acture of bearings, storage batteries,
pewter, lead electrodes, and glass (1,2,3,4,5,6).
Over a hundred mineral ores containing antimony exist
e^h T£e,mostpPortant is the antimony mineral
nSft 3? = £ mineral is usually mined for primary
production. The most important ores from the
standpoint of their wastewaters containing antimony are
silver and lead ores from Idaho, Montana, and Nevada. The
following minerals, used for the extraction of base metals,
contain significant amounts of antimony: tetrahedrite (the
sultide of zinc, copper, and antimony), up to 29 percent
antimony; jamesonite (the sulfide of leadand antimony?, up
to 35 percent antimony; and bournonite (the sulfide of
Anf?^' 'i and antin»ony), up to 25 percent antimony (1).
Antimony is also associated with gold and mercury-bearing
The following sections report the available data on
antimony presence in the raw wastewater and treated efflu-
Smeltin*> *nd other industries
REPORTED DATA
Nonferrous Metals Mining and Milling
Mine il ?ne?^t> theiA'?- A£timony Corporation, whose Babbit
Mine is in Thompson Falls, Montana, is the only domestic
company mining and milling antimony as a primary product .
The ore is extracted from an underground drift mine- there
is no wastewater discharge from thl mine. The adjacent
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Water in this operation is added between the crushing and
grinding stages at the rate of 305 to 382 cubic meters per
day (3). Pollutants in the raw wastewater originate from
the solubilization and dispersion of ore constituents and
also from the introduction of the milling reagents. Table 1
shows the chemical composition of raw wastewater discharged
from the antimony mill (3). This wastewater is directed to
the retention ponds at the rate of 286 to 343 cubic meters
per day. There is no discharge from the retention ponds
(3). An analysis of the pond water gave the following
results for the major heavy metals (3):
Total antimony 0.24 mg/1
Total arsenic 0.07 mg/1
Total zinc 0.09 mg/1
Tailings solids contain an average of 0.4 mg/1 anti-
mony in the form of SboOo, HSb20r, and/or Sb20o'Sb20c
(Personal communication: Mr. John Lawrence, D.5. Antimony
Corporation). Some stibnite (Sb-^S^) may also be present in
the solids. Dissolved antimony would be derived from the
tailings, hence could be in either a trivalent or pentavalent
state.
The Sunshine Mining Company, located in the Coeur
d'Alene district of Idaho, recovers antimony by electro-
winning from the NaOH leach of silver-copper ore. The
effluents from the leach plant are directed to a tailings
pond. The supernatant from the pond is discharged to the
surface water (1975). Table 2 gives a comparison of the raw
wastewater from the antimony leach plant and the effluent
from the tailings pond. The tailings pond receives both
wastewater from the leach plant and the tailings from the
flotation process at the silver mill. The influent and
effluent samples collected at the tailings pond during the
period 1969 to 1971 showed mean influent, seepage, and
effluent Sb concentrations to be 8.9, 79.8, and 33.3 mg/1,
respectively (7). This strange distribution of antimony can
be explained by the daily variation of antimony in the
influent to the pond. Thus, the same study found antimony
in the influent to the pond to be in concentrations above 60
mg/1 in the morning hours and below 5 mg/1 (which was the
lower limit of detection) during the rest of the day (7).
In 1971 the Sunshine Mining Company effluents were
reported to contain 5 to 40 mg/1 of antimony (8). Plans,
however, were underway to install a system for complete
recycle of the antimony in the effluent from the electroly-
tic production of antimony back to the antimony plant in-
fluent (ore leach). Nevertheless, data from 1975 show the
presence of significant amounts of antimony in the tailings
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TABLE 1. CHEMICAL COMPOSITION OF RAW WASTEWATER DISCHARGED
FROM ANTIMONY FLOTATION MILL (3)
Parameter
PH
Acidity
Alkalinity
Color
Turbidity (JTU)
TSS
TDS
Hardness
Chloride
COD
TOG
Al
As
Be
Ba
B
Cd
Ca
Cr
Cu
Total Fe
Pb
Mg
Total Mn
Concentration
(mg/1)
8.3*
8.5
11.0
113+
170
149
68
40
1.5
43
7.8
6.2
0.23
0.002
0.3
0.01
0.103
0.57
0.04
0.12
18.8
0.13
1.93
0.40
Parameter
Hg
Ni
Tl
V
K
Se
Ag
Na
Sr
Te
Ti
Zn
Sb
Mo
Oil and grease
MBAS surfactants
Cyanide
Phenol
Fluoride
Total kjeldahl N
Sulfide
Sulfate
Nitrate
Phosphate
Concentration
(mg/1)
0.0038
0.10
0.05
0.2
3.5
0.036
0.02
2.0
0.11
0.2
0.5
4.35
64.0
0.2
1
1.9
0.01
0.022
0.1
1.3
0.5
16.5
2.55
0.05
*Expressed in pH units.
Expressed in cobalt units.
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TABLE 2. ANTIMONY LEACH PLANT EFFLUENT AND TAILINGS
POND EFFLUENT AT THE SUNSHINE MINE. 1975 (8)
Major wastewater
parameter
pH
Total solids
Suspended solids
Dissolved solids
Acidity
Alkalinity
Hardness
Chlorides
COD
TOC
so4
Oil & grease
Sulfide
As
Cd
Ca
Cu
Pb
Mg
Hg
Mn
Te
Zn
Sb
Mo
Leach plant
effluent (mg/1)
13.2*
355,000
355,000
128
1,500
7,000
430
1.3
0.22
0.25
0.0222
0.02
25
0.02
24
5.72
Tailings pond
effluent
(mg/1)
8.0*
496
20
476
14
45
137
2
51.5
12
368
10
0.5
0.73
0.02
19.5
0.02
0.1
13.5
0.0023
1.3
0.3
0.02
4.4
0.66
^Expressed in pH units,
8
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pond effluent. The flew rate of discharge from the tailings
pond in 1975 was 3.4 m /min.
A recent visit was made to the Sunshine Mining Company
to discuss present levels of antimony in the leach plant
bleed stream and tailings pond effluent. Total antimony
levels were found to be higher in the leach plant bleed
stream than shown in the 1975 data, namely 75 mg/1 in March
and 160 mg/1 in May of 1978. Total antimony levels, however,
for tailings pond effluents did not exceed 0.8/mg/l for both
of these months (Personal communication: Mr. Emit Fattu,
Sunshine Mining Company). Possible forms of soluble antimony
from the leach plant bleed stream include Na^SbS^, NaoSbS, ,
and H/07Sb2.H20*2Na, with the final two forms being most
probable (Personal communication: Fattu). Thus, pentavalent
antimony is the most probable dissolved form.
During the survey of seven mines in the Coeur d'Alene
district (1969 to 1971), antimony was found only at the
Sunshine Mine (7). The limit of detection, however, for
this particular study was 5 mg/1. In 1975 (3) and 1977 (8)
antimony was found in the raw wastewater of ferroalloy,
silver, and mercury mines and mills. Table 3 summarizes
available data for these mines. The flow rates of the raw
wastewater for these mines were: Mine 6101, 10,170 nT/day;
Mine 4401, 3,680 mj/day, and Mine 9202, 5,390 mg/day (9).
Primary and Secondary Smelting of Nonferrous Metals
Antimony presence in lead, copper, zinc, and other
metal concentrates ranges from insignificant to several
percent. Because of the ubiquity of antimony, it may be
found in a wide range of concentrations in the wastewaters
from smelting operations. Table 4 presents available data
on antimony in wastewaters from primary and secondary non-
ferrous smelting, excluding secondary lead. Secondary lead
smelting is a source of secondary antimony. Antimony is
persistently present in significant concentrations in the
wastewater from the secondary lead plants. Table 5 gives
the chemical composition of wastewater streams from six
secondary lead plants. The plant numbers in the table are
given as they appear in the EPA Development Document for
Effluent Limitation Guidelines for Miscellaneous Nonferrous
Metals "
Other Industries
Antimony and its compounds are widely used in the
production of paints and in the dye houses of the textile
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TABLE 3. COMPOSITION OF ANTIMONY-CONTAINING RAW
WASTEWATER FROM THREE MINES AND MILLS (3)
Mine and mill
description
Wastewater stream
Wastewater parameter
pH (units)
Total suspended solids
Volatile suspended solids
COD
TOG
Sb
As
Be
Cd
Cr
Cu
Pb
Hg
Nl
Se
Ag
Th
Zn
Phenol
Bis/2-ethylhexyl phthalate
Di-n-butyl phthalate
Diethyl phthalate
2 , 4-dimethylphenol
Mine No.*
6101
Molybdenum
Tailings pipe
effluent
(mg/D
10
10
5
1.3
0.01
51
2.3
13.5
Mine No.*
4401
Copper
Influent to
tailings pond
(mg/1)
7.4
397,000
62,800
15,100
25
18
0.8
0.02
0.01
0.38
15
27
0.007
0.39
0.04
2.2
0.1
4.6
0.01
15
27
51
Mine No.*
9202
Mercury
Influent to
tailings pond
(mg/1)
8
139,000
4,300
60
1
53
1.1
0.09
0.56
0.46
0.85
1.0
230
1.6
0.01
0.01
76
2.4
76
9.2
56
66
140
*Mine numbers are taken from Reference 3.
10
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TABLE 4. ANTIMONY CONCENTRATIONS IN WASTEWATERS FROM PRIMARY AND
Smelter
Wastewater stream no.
Antimony concentration (mg/1)
Smelter
Wastewater stream no. 1
Antimony (mg/1) 2.9
1
8
Secondary
copper plant 1
234
135 20 1
Columbium/ tantalum
Plant 1 Plant 2
2
4.5
3 123
0.2 20 4 30
Secondary
copper plant 2
5 1
3 2
Secondary
silver
12 3
12 .7 1.5
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TABLE 5. RAW WASTE CHARACTERISTICS - SECONDARY LEAD SMELTERS (10)
Water analysis (mg/1,
Type of
Waste Plant No. pH
Battery acid 4131 <1.0
4132 <1.0
4133 <1.0
4133 (case wash- 1.15
water)
4134 <1.0
Scrubber 4131 (SO, scrubber) 1.5
water
4132 (reverbatory & 4.75
blast furnace)
H-1 4132 (refining 7.90
10 kettle)
4133 (refining 5.50
kettle)
Influent to 4131 1.3
treatment
plant 4132 1.25
4133 <1.0
4135 <1.0
Plant runoff 4131 4.55
4134 6.35
Non-contact 4133 7.7
cooling
water 4136
TSS
444
1,390
382
258
1,050
2,320
85
12
94
134
1,320
568
1,390
10
248
3
IDS
37,800
-
-
10,400
-
209,000
462
2,270
3,740
10,200
1,160
-
-
3,720
898
230
Pb
283
37.1
115
146
6.13
54
191
6.24
970
76
677
45.4
71.6
1.85
164
0.3-
10.2
Sb
31.9
23.8
60.0
8.3
62.0
8.3
1.0
28.0
170
8.5
43.0
91.0
210
0.4
5.9
1.50
0.79
Cd
4.92
0.075
1.022
0.120
5.23
1.62
0.432
0.030
0.215
0.83
0.345
1.55
7.54
0.048
0.872
<0.005
0.04
As
0.850
4.6
1.6
0.4
2.7
1.250
1.4
430
146
0.024
1.8
2.6
5.5
0.053
0.2
<0.1
0.22
except pH)
Zn
1.72
1.09
2.58
0.410
4.21
0.17
0.900
0.40
0.460
0.53
1.13
4.43
245
1.13
1.97
O.J6
0.13
Cu Fe
1.
3.
2.
0.
4.
0.
23
15 16.4
46 96.0
484 114.0
54 69.0
11
0.025 2.32
0.
1.
0.
1.
3.
20.
0.
0.
0.
0.
144 1.42
44 2.20
41
21 19.1
26 278
9 403
18
23 4.84
020 0.07
015
S04
27,000
123,000
87,500
6,250
170,000
58,500
11
310
10
6,600
10,500
52,500
90,000
1,200
330
11
-
Oil
and
Grease NH
-
-
-
-
-
-
-
-
-
-
11. 0
14.8
236 17.5
-
-
-
-
-------
industry. Table 6 shows analysis of a typical effluent from
a paint plant (6). Table 7 gives the chemical composition
of a dye house effluent before and after treatment (pilot
plant type). Antimony also appears in trace concentrations
in the coal-ash basins from coal-fired power plants (5).
TABLE 6. TYPICAL EFFLUENT ANALYSIS OF A
PAINT PLANT (6)
Typical for a complete spectrum Latex paint Alkyd resin
of a paint plant (mg/1) manufacture (mg/1) manufacture (mg/1)
COD
BOD
PH
Suspended solids
Total solids
Chromium
Zinc
Lead
Antimony
Tin
Iron
6200
4200
7-10
700-2000
0.2
6
5
10
20
13,000
8,000
7-11
6,500
0.02
8
2
3
15
3
500
300
7
1,300
0.1
0.4
0.8
2
3
2
TABLE 7. METALLIC POLLUTANTS IN A DYE HOUSE WASTEWATER
STREAM BEFORE AND AFTER PILOT PLANT PEAT
MOSS TREATMENT (4)
Metal
Cyanide
Fluoride
Aluminum
Barium
Cadmium
Chromium (+6)
Chromium (+3)
Copper
Iron
Lead
Manganese
Nickel
Silver
Zinc
Antimony
Mercury
Before treatment (mg/1)
UL
NA
NA
NA
25
300
300
250
31.5
8.4
NA
67.5
NA
7.5
30.0
15.0
After treatment (mg/1)
0
NA
NA
NA
0.1
0.04
0.25
0.2
0.25
0.025
NA
0.05
0.05
0.08
0.50
0.01
NA = Not ava-llaMo
UL = Unlimited
13
-------
WASTEWATER TREATMENT
Nonferrous Metals Mining and Milling
Since mining and milling are usually adjacent opera-
tions, the wastewaters from both operations are usually
combined and flow to one treatment system. Treatment usually
consists simply of sedimentation; i.e., use of one or more
tailings ponds to remove suspended solids and, in some
cases, heavy metals. Depending on solids loading and settling
characteristics, a flocculant may or may not be necessary.
If needed, the flocculant is usually combined with the
influent stream before it enters the pond.
Tailings ponds may or may not have a point-source dis-
charge depending on availability of water, effluent char-
acteristics, leakage, and evaporation-precipitation ratios.
Mining and milling operations in arid regions usually com-
bine zero discharge treatment with almost total water
recycle.
Although no treatment system has been designed to
specifically remove antimony, there is usually a net reduc-
tion in total antimony from the influent to the effluent of
the tailings pond, suggesting that the antimony is largely
suspended and/or is captured via co-precipitation with other
flocculating materials.
Table 8 presents data on suspended solids and total
antimony levels in tailings pond influents and effluents
from selected mining and milling operations having signi-
ficant levels of antimony in their raw wastewaters. It is
apparent that the antimony removed is very much related to
the removal of suspended solids.
TABLE .8. SUSPENDED SOLIDS AND TOTAL ANTIMONY REMOVAL
BY MINE TAILINGS POND (8)
Mlne Removal
tyPe Influent, mg/1 Effluent, mg/1 efficiency (%)
SS Total Sb SS Total Sb SS Total Sb
Silver/ 396,000 18 18 0.2 99.9+ 98.5
lead
Mercury 139,000 53 1.6 0.2 99.94- 99.6
*Zero discharge system, sample was taken from recycle sump.
14
-------
The data suggest that some soluble antimony may be
present which is not removed by the tailings pond. All
available data indicate, however, that total antimony levels
in effluents of non-zero discharge tailings ponds from known
mine and milling operations are usually far less than 1
mg/1, excepting the Sunshine Mining Company effluent, which
has been found to range from 0.59 to 1.64 mg/1 total anti-
mony in recent years (1975 and 1978) (11,12). Data from
March and May of 1978 indicate that antimony levels in the
Sunshine effluent have been averaging approximately 0.7 mg/1
(11). Sunshine is an exception because of its antimony
leaching operation, which has been found to contain as much
as 160 mg/1 total antimony in the bleed stream flowing to
the tailings pond (Personal communication: Fattu).
Secondary Lead Smelting and Refining
Existing treatment processes employed in the industry
consist of:
Lime treatment
Ammonia treatment (pH adjustment).
In lime treatment systems, quicklime (CaO) or hydrated lime
(Ca(OH)2) is used to neutralize acidity and to precipitate
dissolved heavy metals. Contact with lime is followed by
clarification or settling. Flocculants are often added to
promote faster settling.
o
The typical amount of lime used to neutralize 83 m /day
of wastewater was given as 1,000 kg of Ca(OH)?/day. The con-
centration of antimony in the effluents from this lime
treatment system was reported to be 1.3 mg/1. Tables 9 and
10 show respectively effluent concentrations and a comparison
of influent and effluent characteristics for a secondary
lead plant.
Treatment with ammonia is used in secondary lead smelt-
ing and refining primarily to neutralize waste battery acid
prior to its discharge into sanitary sewers. Ammonia is not
effective in the removal of antimony. The following is the
reported data on antimony removal with the ammonia treatment
system (10):
Antimony, mg/1
Influent Effluent
Case 1 43.0 1.5
Case 2 91.0 77.0
Case 3 210.0 47.0
15
-------
TABLE 9. MONTHLY AVERAGE AND MAXIMUM EFFLUENT CONCENTRATIONS (1975)
LIME TREATMENT SYSTEM, SECONDARY LEAD PLANT 4131, (10)
Discharge levels (mg/1)
pH (units) TSS Pb Sb As Cu Zn Ni
Mini- Aver- Maxi- Aver- Maxi- Aver- Maxi- Aver- Maxi- Aver- Maxi- Aver- Maxi- Aver- Maxi- Aver- Maxi-
Month mum age mum age mum age mum age mum age mum age mum age mum age mum
Jan. 3.10 7.72 8.95 4,085 5,902 0.39 2.24 1.16 2.61 <0.004 0.037 0.033 0.134 0.103 0.305 0.004 0.18
Feb. 5.24 7.33 8.55 4,058 8,326 0.37 1.63 1.43 3.10 <0.004 0.015 0.038 0.093 0.258 0.670 0.132 0.60
March 6.88 7.57 8.29 4,313 8,776 0.57 1.43 1.33 2.30 '0.009 0.033 0.039 0.068 0.352 1.29 0.104 1.22
April 6.97 8.14 10.00 4,096 5,892 0.35 0.88 0.76 1.39 <0.007 0.027 0.032 0.067 0.112 0.51 0.051 0.14
May 3.10 7.54 9.60 4,009 5,120 0.36 2.30 0.69 1.43 <0.004 0.026 0.033 0.130 0.005 0.45 0.038 0.12
June 7.30 8.03 9.70 3,766 4,638 0.104 0.32 0.79 1.96 0.003 0.008 0.021 0.043 0.013 0.045 0.019 0.039
July
Aug. 7.04 8.31 10.20 3,904 5,686 <0.072 0.17 0.80 1.25 <0.002 0.002 0.020 0.034 0.033 0.061 0.015 0.061
Sept. 7.00 7.94 10.15 4,080 6,458 0.16 0.74 0.69 1.61 0.003 0.019 0.027 0.054 0.020 0.20 0.040 0.090
Oct. 2.60 7.93 9.35 4,498 6,078 0.228 2.65 0.83 1.64 0.003 0.007 0.033 0.22 0.050 .-
-------
TABLE 10. PERFORMANCE OF LIME TREATMENT AT SECONDARY
LEAD PLANT 4131 (10)
Parameter
TSS
TDS
PH
Pb
Sb
Zn
As
Cu
Cd
Fe
so4
Influent, mg/1
134
10,200
1.3*
76
8.5
0.53
0.024
0.41
0.83
6,000
Effluent, mg/1
24
5,120
8.85*
0.41
0.70
0.03
0.03
0.03
0.005
2,530
*Expressed in pH units.
17
-------
SECTION 5
ANTIMONY REMOVAL TECHNOLOGIES
ANTIMONY CHEMISTRY
Antimony is a group five element commonly found in
nature as antimony trisulfide (stibnite) or in lower-grade
ores as antimony trioxide. It may exist in dilute solutions
as Sb+3 or Sb+5 cations or more probably as the SB(OH)g anion
or other anionic complexes in which SbO* is the nucleus
(13,14,15).
In wastewaters from mines and smelters, the main anti-
mony compounds of concern are antimony trioxide, antimony
trisulfide, organic chelates of antimony, and hydrolyzed
antimony complexes. Antimony trioxide and antimony trisul-
fide are soluble below 1.0 mg/1 and 1.7 mg/1, respectively.
Below these concentrations, hydrolysis of antimony becomes
particularly significant. Little is known about the stab-
ility and formation of organic antimony chelates.
Stability constants for antimony complexes either are
not readily available or differ widely from one data source
to another. Formation constants of hydroxy complexes are
remarkably large when compared with most other ligands (15).
This explains why with most highly charged metal ions, such
as antimony ions, hydroxides or hydrous oxides are the only
thermodynamically stable forms, except for multidentate
ligands (15). H[Sb(OH)6l is thought to be the stable form
in most natural waters tl).
Antimony in dilute solution undergoes deep hydrolysis,
leading to the formation of its colloidal basic salt con-
taining SbO+ or its hydroxide (13). As was postulated by
Bronsted, multivalent ions participate in a series of con-
secutive proton transfers. Hydrolysis may go beyond the
uncharged species to form anions such as Sb(OH)g (15)
Like all metals, antimony is in a continuous search for
a partner to improve its stability. The coordinated water
may be exchanged for a preferred ligand. Metals in this
respect are Lewis acids, able to accept a pair of electrons.
Metal ions have speciation which is dependent upon the
18
-------
stability of the hydrolysis products and the tendency of the
metal ion to form complexes with other ligands.
Literature on antimony removal technology, with the
exception of that on lime precipitation, is sparse, scat-
tered, and often contradictory. Researchers for this study
were unable to find a mine that treats its wastewater for
antimony. Very little laboratory work has been done on
developing removal technology. Within this framework,
antimony removal technologies for which some information
exists are discussed in the following subsections.
SULFIDE PRECIPITATION
In most cases, the theoretical solubilities of heavy
metal hydroxides are considerably higher than the solubil-
ities of the sulfides. It is this property of heavy metal
sulfides that makes sulfide precipitation attractive. The
Sulfex process patented by Permutit is among the most
attractive of the sulfide precipitation methods. In con-
ventional sulfide precipitation it is nearly impossible to
consistently add the exact amount of sulfide required
Excess quantities of the sulfide source liberate hydrogen
sulfide. This problem is eliminated in the Sulfex process
by adding another heavy metal sulfide whose solubility is
too low to release hydrogen sulfide but high enough to react
with heavy metals (16).
Two metal sulfides commonly used are iron sulfide
(solubility - 3.4 x 10-5 mg/1) and manganese sulfide (2.1 x
10 J mg/l) (16). For a significant number of heavy metals
this process is very effective, since the concentration of
free sulfide at equilibrium is many orders of magnitude
lueaEef^for iron sulfide than it is for other heavy metals.
The Sulfex process, however, would not be effective in
reducing dissolved antimony to recommended levels of less
than 0.5 mg/l, and sulfide treatment in general is not
adequate to obtain the desired levels. The reasons why
Sulfex and sulfide precipitation are not recommended are as
follows:
Antimony trisulfide has a solubility of 1.7 mg/l.
Sulfide precipitation cannot be expected to remove
antimony sulfide below that solubility, assuming
equilibrium conditions. In treating an ethylene
glycol wastewater containing antimony by sulfide
precipitation, concentrations of less than 3.5
mg/l were not attainable. Details of this exper-
iment are not available.
19
-------
Most heavy metals commonly found in mining waste-
waters have solubility as sulfide lower than
antimony and would precipitate first. Iron sul-
fide and magnesium sulfide could not be used to
control hydrogen sulfide formation because they
are less soluble than antimony sulfide. Conse-
quently, there would be no control for the produc-
tion of hydrogen sulfide.
Since there is no control for excess hydrogen
sulfide, there is the potential for altering
antimony sulfide to a soluble form. Antimony
in excess sulfide concentration forms soluble
anionic thio-complexes.
LIME PRECIPITATION
Lime precipitation is the most common method of remov-
ing antimony from industrial wastewater. The principle
involved in lime precipitation is that metals have some low
point in their solubility curve at some alkaline pH value.
Simple equilibrium calculations for metal hydroxides and
oxides have few meaningful examples in the real world. The
reasons for the unpredictability include the fact that most
metal hydroxides or hydrous oxides are amphoteric and dis-
solve at some alkaline pH. It is impossible to obtain the
optimum pH for precipitation of metals in a complex mixture.
The aqueous chemistry of antimony ions cannot be well
defined. If antimony behaves similarly to other highly
charged trace elements, (i.e., bismuth; it will undergo
consecutive proton transfers. Anionic colloidal hydroxo-
polymers will form with increasing pH and eventually pre-
cipitates will form. Consequently, antimony trioxide
solubility does not control the solubility of antimony in
natural waters. Coagulation is usually effected by metal
ion hydrolysis; little information is available on the
formation of antimony hydroxides. The kinetics of the
formation of antimony precipitates is not available. While
the establishment of hydrolysis equilibria is generally very
fast when hydrolysis species are simple, this is not the
case for antimony, where progressive condensation and hydro-
xylation lead to multimeric soluble intermediates and
finally to insoluble precipitates. The kinetics of hydroxo-
precipitation need to be defined for antimony if lime
precipitation is a desired treatment method. It is con-
ceivable that under proper conditions lime precipitation
could reduce antimony concentration below the solubility
limit for antimony trioxide. It would be almost impossible,
however, to consistently obtain these ideal conditions in
complex wastewaters from mines.
20
-------
Hannah et al. (13) investigated lime precipitation for
treatment of antimony present at initial concentrations of
0.6 mg/1. At pH 11.5, removal efficiency was 28 percent. It
is likely that hydrolysis had proceeded to the extent that
the soluble hydroxo-polymers of SbO were largely present
but hydrolysis was extensive enough that the hydrolyzed
precipitate had begun to form.
The complex hydrolysis reactions of antimony are com-
plicated by the presence of other metals in the mine waste-
water. Furthermore, any antimony present as the trisulfide
can be solubilized by the alkaline pH (13).
Since this study is concerned only with treatment tech-
nologies capable of reducing residual antimony levels to
less than 0.5 mg/1, lime precipitation is not recommended
and will not be discussed further in this section.
Two other treatment technology areas not covered exten-
sively in this section are plant-specific technologies and
technologies which are primarily geared toward water recov-
ery. Plant-specific technologies include zero discharge,
recycle, reuse, and solar evaporation options which may be
applicable for specific locations and circumstances, but are
not generally usable. Technologies which have water recov-
ery as their primary purpose include distillation, freeze
drying, reverse osmosis, and electrodialysis. These tech-
nologies recover water but usually leave a concentrated
solution which requires further treatment or disposal.
ION EXCHANGE
Process Discussion and Process Variables
Ion exchange is an attractive method for removal of
small amounts of impurities from dilute wastewater. Im-
portant industrial applications for metal ion removal and
recovery include rare earth separation, copper and zinc
recovery in rayon production, and removal of metals such as
gold, copper, nickel, zinc, and chromium from plating rinse
waters.
State of the Art
Aside from the conventional anionic or cationic ex-
change columns, there are several new developments in ion
exchange which have potential application for trace element
removal. One possibility is chelating resins. The forma-
tion of metal chelates with the appropriate resin makes
possible the removal of metal ions from solution even in the
presence of high concentrations of non-complexing ions.
21
-------
Chelating resins have a marked selectivity for metals cap-
able of forming coordination complexes; antimony falls into
this category. At present, however, chelating resins are
more costly and the kinetics of adsorption is significantly
slower than with conventional exchange resins (Personal
communication: Kenneth C. Jones, Mining Chemicals Group, DOW
Chemical Co.). This application should be investigated only
where conventional resins fail to achieve the desired treat-
ment level.
Another development in the area of ion exchange util-
ized by metallurgical industries is liquid ion exchange.
This process, which has been adopted successfully by the
uranium and copper industries (17), has the potential for
recovering metals from industrial wastes.
Liquid ion exchangers such as oil-soluble, water-
immiscible, alkylsubstituted phosphoric acid (HDPA) are used
in ion exchange. For instance, thorium has been extracted
from an acid solution by exchanging the proton of HDPA for
positively charged thorium. Stripping the extractant is
chemically identical with regenerating ion exchange resin.
Similarly, liquid exchangers containing sulfonic, carboxy-
lic, and acidic groups have been developed for cation ex-
change and exchangers containing amines have been developed
for anion exchange (18).
As far as conventional ion exchange is concerned, there
are currently several contactors available to house the ion-
exchange resin. Continuous countercurrent exchangers have
the advantage of greater resin utilization and higher
chemical efficiency. The most prominent and promising
countercurrent exchangers include:
Higgins, in which the resin is hydraulically moved
as a consolidated resin bed up through a contact-
ing zone. Solution flow is in the direction
opposite to resin movement except for brief per-
iods when it is cocurrent. All process steps such
as loading, rinsing, and regeneration take place
in one unit. The process has broad general
application (19).
Asahi, in which the resin moves as a consolidated
resin bed down through the contacting zone in a
cyclical manner. Each processing step takes place
in a separate vessel. The process is in use in
Asahi's cuproammonium rayon plant for recovery of
copper from waste spinning solution (19).
22
-------
Aconex, which consists of fixed-bed columns which
rotate in a merry-go-round arrangement, with the
liquid feed distributor above the columns divided
into sections to accommodate all process steps
(19).
Fixed-bed columns will probably dominate the market for
several years. Several variations of fixed-bed exchangers
currently exist. For example, the counterflow process is a
method in which the regenerant is passed upward against a
simultaneous downflow of water that joins the regenerant
solution at a collector located at the surface of the resin
bed. This provides high regenerant efficiency and generally
a high-quality effluent (19).
Applicability to Antimony Removal
Although nearly every known metal has been investigated
for its treatability with anionic and cationic exchange,
commercial-scale applications are far more limited. Ion
exchange has reportedly been used effectively for the re-
moval of antimony from ethylene glycol wastewater in pilot-
scale applications but data are not available (Personal
communication: Mr. Button, Rohm and Haas). An anion ex-
change resin is applicable to the removal of antimony with a
theoretical exchange capacity reported to be 0.07 g/cnT
(20). This supports the hypothesis that the prevalent aqueous
form of antimony is anionic (due to extensive hydrolysis).
Antimony has been successfully treated with Rohm and
Haas Amberlite CG-400, a strong basic chromatograph grade
exchange resin (21). Presumably a less costly grade anion
exchange column would be used on a commercial scale. Dow
Chemical manufactures strong base anionic exchange resins,
but data on the effectiveness of these resins for antimony
treatment are not available.
Final application of ion exchange to the treatment of
complex wastewaters from mines or smelters containing anti-
mony will require case-by-case examination of the wastewater
components. Exchange columns specific for antimony are not
available. The selectivity of a resin for antimony needs to
be determined in the specific complex wastewater. The
23
-------
presence of interfering substances such as humates will need
to be investigated.
Pollution Potential
The major problem with the use of ion exchange is the
regenerate waste which is produced. The regenerate brine
must be treated, although generally this is more easily
accomplished than treating the original waste. A large
percentage of the regenerating chemicals pass into the
effluent unchanged, reflecting the inefficiency of the
process.
STARCH XANTHATE
Process Discussion
A water-insoluble starch xanthate (ISX) offers a unique
method for removal and recovery of heavy metals from waste-
water. ISX acts as an ion-exchange material removing the
heavy metal ions and replacing them with sodium and mag-
nesium. The average capacity is 1.1 to 1.5 meq of metal ion
per gram of ISX (22). For use in heavy metal removal, a
product containing both sodium xanthate and magnesium xan-
thate is added to the effluent as a solid or slurry, allow-
ing the pH to rise above 7 for optimum removal (23). Metal
removal is instantaneous. For continuous flow streams the
aid of a clarifier, centrifuge, or filter should be used to
settle the sludge. The sludge is roughly 50 percent solids
and can be further increased in solids content to about 90
percent after three hours of settling. Metals can be recov-
ered from the ISX sludge by nitric acid treatment or in-
cineration.
State of the Art
There are currently few commercial applications of ISX
for heavy metal removal, although 50 to 55 companies are now
investigating the feasibility of its use. A plating company
in the Northeast has been using ISX for about three years
as a filter precoat to reduce concentrations of copper,
nickel, and tin-lead (Personal communication: Mr. A. Bessimer,
Extract Systems).
ISX has been evaluated for treatment of copper etching
rinse waters. Copper concentrations were lowered from 28 to
54 mg/1 to less than 0.1 mg/1 using ISX (22). This research
was conducted as part of an overall evaluation of wastes
treatment from the plating industry. ISX systems have also
been designed for copper-dye removal (4.73 x 10 liters) and
24
-------
copper-lignin removal for a stream containing 100 mg/1 of
copper at 90.7 m /hr (22). ISX has a limited stability in
solution and would have to be prepared every few days and
then diluted for daily use. It is currently available in
solid form from at least one supplier, Allen Bessimer Extract
Systems (Personal communication: R.E. Wing, U.S. Department
of Agriculture).
Application to Antimony Removal
The effectiveness of starch xanthate in removing anti-
mony from wastewater has been investigated in bench-scale
tests: 0.05 g/1 of starch xanthate removed 5 mg/1 of anti-
mony to roughly 0.01 mg/1 (Personal communication: Mr. John
Zschiegner, J&J Materials).
The Mogul Corporation performed laboratory investiga-
tions on a wastewater stream containing antimony at 5.0 mg/1
and a COD of 2000 mg/1 (Personal communication: Mr. John
Bell, Mogul Corp., Chargrin Falls). Of the four processes
shown below, only starch xanthate could effectively reduce
antimony to the target 0.5 mg/1:
Lime precipitation did not produce antimony
levels below 1 mg/1.
Oxidation with chlorine and permanganate had no
effect.
Sulfide precipitation was effective only to 3.5
mg/1.
Starch xanthate effectively reduced antimony level
to 0.5 mg/1.
Further investigation into antimony removal by starch
xanthate would be required for commercial application.
Little is known about how other trace metals in the complex
effluent would effect antimony removal.
Pollution Potential
The ISX method has a very low pollution potential. The
ISX-metal sludge dewaters easily up to a 90 percent solids
level (22). If metal recovery is warranted, the metals can
be released from ISX by treatment with nitric acid, thereby
avoiding potential leaching problems. Furthermore, nitric
acid treatment allows recovery of the crosslinked starch,
although it is neither practical nor economical to reuse the
starch. If the sludge is landfilled without metal recovery,
leaching potential is expected to be limited, since the
metal ions are tightly bound to the ISX (23).
25
-------
ACTIVATED CARBON
Process Description
Adsorption is a phenomenon long recognized for its
value in scavenging and retaining soluble metals even at
very low concentrations. While activated carbon adsorption
is utilized only to a limited extent by the mining and
metals industry, under proper conditions of pH and oxidation
certain metals will be adsorbed very strongly.
Lignite-based activated carbons are generally used for
trace metal recovery. Lignite-based carbons are effective
because of the distribution of pore size and the large
volume of pores resulting in a high surface area per unit
weight. Probably the most important factor in metallic ion
adsorption is the pH. Several applications have shown that
adsorption improves with decreasing solubility (24). By
maintaining the pH at low solubility, carbon loading can be
greatly improved.
Several possible mechanisms exist for heavy metal
removal by activated carbon (25):
Ion Exchange - All commercial activated carbon
contains some functional groups containing oxygen
on the carbon surface. Since the basic carbon
skeleton is graphitic in nature, phenolic, car-
boxylic, ether, peroxide, lactone, and hydroxyl
groups may exist.
The total number and type will depend upon thermal
history and upon the oxidants to which it is
exposed. Exchangeable sites act in a manner
analogous to ion exchange. Most exchange groups
are cationic acceptors, although some anionic
acceptors do exist.
Filtration or Entrapment - Granular beds of acti-
vated carbon can act as a very effective filtra-
tion device. Strong surface forces surrounding
the suspended or colloidal material induce the
coagulation of particles clinging to the rough
activated carbon surfaces.
Reduction to Metal or Oxidation to Insoluble
Forms - The carbon surface may contain several
impurities such as ferrous salts or sulfides which
can reduce certain metals to elemental forms.
Similarly, in the presence of dissolved oxygen,
oxidation of certain trace elements occurs.
26
-------
True Adsorption - In true adsorption the dissolved
species are attracted to the gross interior sur-
face of the carbon and establish dynamic equil-
ibrium between a concentrated surface layer and a
dilute solution in the pore space.
State of the Art
The existence of many surface phenomena responsible for
trace metal removal by activated carbon offers several areas
of research for potential improvements in the activated
carbon process.
One area of current investigation is the development of
carbons with specially prepared oxygenated surfaces, which
enhance adsorption by reacting with cations to form salts.
There are no commercial processes employing such carbons,
but several Russian investigators have observed increased
carbon activity in the presence of oxidation surfaces (25).
Chelation has been used effectively in activated carbon
treatment. Cyanide, EDTA, thiourea, lignins, etc., are
under investigation as complexing agents to improve adsorp-
tion by activated carbon (25). Another variation of chela-
tion which offers potential for improving trace element
removal is referred to as "loaded carbon." Specific che-
lating and complexing agents are adsorbed onto the carbon,
providing specific sites for metal adsorption. Sorption
capacity corresponds to the stability of complexes formed by
the ions and consequently the carbon can be made more selec-
tive. Some of the chelating agents under investigation for
removal of certain trace elements are: 8-hydroxyquinoline,
citric acid, tartaric acid, salicyladoxime, and dibenzoyl-
me thane (25).
The choice of whether to use powdered or granular acti-
vated carbon is generally evaluated on a case-by-case basis.
Granular carbon, however, is ordinarily the method of
choice for a continuous process. Its overall efficiency for
a given operation can be greater than that for powdered
carbon because a countercurrent effect is attained in a
granular carbon bed.
There are currently several applications of activated
carbon treatment in the metals industry which suggest that
this technology could be used in treating antimony from mine
wastes.
Carbon has been successfully used in this country
and in Canada for removing mercury from mercury
cell chlorine/caustic plant wastewater. The
carbon has been found to be effective in dilute
27
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solutions and has capacity for the metal in sev-
eral forms (26).
Granular activated carbon has been used success-
fully to recover gold from low-grade ores and
tailings (26).
Granular activated carbon has been used to recover
molyoxides from sulfide tailings (26).
Application to Antimony Removal
The results of Sigworth have shown that the optimum pH
for antimony removal is 0 to 1 (27). At this pH the degree
of loading is 16 percent adsorbed, based on carbon weight.
Antimony adsorption has been found to be nearly linear with
carbon dosage (Personal communication: Mr. J. Dick, ICI.
United States). Table 11 indicates that at the optimum pH,
antimony is removed more effectively than most metals and
that tin was the only other metal effectively removed in
this same pH range. In mining wastewaters where several
other trace elements may be present in concentrations high
enough to warrant treatment, activated carbon, at ideal
conditions for antimony removal, will not remove most trace
elements.
TABLE 11. ACTIVATED CARBON ADSORPTION OF SELECTIVE METALS
Metallic
ion
Copper
Zinc
Nickel
Cadmium
Gold
Lead
Antimony
Molybdenum
Silver
Tin
Approx. %
adsorbed
based on
carbon wt.
2
0.1
0.25
0.6
5-7
3-5
16
16
9-12
36-40
20-22
Solution
Nitrate
Chloride
Chloride
Chloride
Cyanide
Acetate or nitrate
Trichloride
Oxide -pH adjusted HC1
or H2S04
Nitrate
Stannous chloride
Stannic chloride
Best pH
range
5-7
5-7
5-7
5-7
11.4
5-7
0-1
2-3
5-7
0.2-2.0
0.5-2.0
The low pH requirement for antimony removal may make
activated carbon an impractical treatment method for the
large quantities of wastewater under consideration. The use
28
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of chelates to improve adsorption in a neutral pH range
should be investigated. Hannah et al. (13) have illustrated
the effectiveness of activated carbon in conjunction with
precipitation for treatment of antimony. Activated carbon
was found to be moderately effective in polishing the waste-
water. Table 12 illustrates percent removal for precipita-
tion followed by activated carbon. Antimony removal was
investigated in the presence of five other trace elements.
The initial antimony concentration was 0.6 mg/1. Interest-
ingly enough, this treatment was carried out at a neutral pH
and suggests that requirements for the low pH may not be
necessary to attain the desired effluent level.
TABLE 12. PERCENT REMOVAL WITH REMOVAL
TECHNOLOGY COMBINATIONS
Precipitation
method
Lime
FeCl3
Alum
Settling
cone.
21
60
61
Filter
28*
65
62
Old
carbon
64*
71
75
New
carbon
52*
72
71
*Values are cumulative. Settling, filtration, and carbon
adsorption treatments are consecutive rather than individual
Antimony was found to accumulate in the upper part of
the carbon column, indicating an adsorption or filtration
mechanism of removal. Lime precipitation is ineffective at
these low concentrations because antimony forms slightly
soluble sulfides which dissolve in excess alkali.
The improved effectiveness of the old carbon column in
certain cases is probably attributable to the formation of
^S, which increases the probability of metal precipitation.
Secondary Pollutants
Secondary pollutants from activated carbon are formed
during regeneration. Form and extent of pollution depend
upon the type of regeneration method used. Thermal regen-
eration by rotary kiln or multiple hearth furnaces is
frequently used in trace element treatment. This method
would generate antimony oxides, but these can be recovered.
29
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PEAT MOSS
Process Description
Peat moss is a complex material with lignin and cel-
lulose as major constituents. Such constituents contain
polar functional groups, i.e., alcohols, aldehydes, ketonic
acids, phenolic hydroxides, and ethers, which are involved
in chemical bonding (28). Because of the very polar nature
of peat, specific adsorption for dissolved solids is quite
high. In addition, peat has a cellular structure and high
porosity.
The natural capacity of peat to retain cations is
related to the pH of the solution. Above pH 8.5 peat is
unstable, and below pH 3.0 most metals will be leached from
the peat. Treatment methodology begins by precipitating the
metal as a sulfide or hydroxide if the concentration exceeds
1.0 mg/1. The metal sulfide or hydroxide is then circulated
over a mat of peat which physically adsorbs the metal hydrox-
ide or sulfide. The remaining metal in the form of an ion
in solution is then removed by chemisorption. The mat of
Pept i? a °'7 to'1-° percent peat slurry which is pumped to
a feeding loop located above a slowly moving screen belt.
The screen extracts the peat from the slurry and the through
water is recycled to a wetting tank (29).
State of the Art
The peat removal process is accomplished by the pat-
ented Hussong/Couplan process. Hussong-Walker-Davis has
demonstrated the process on an apparatus with a 75,700 I/day
capacity. With a peat mat approximately 2.5 cm thick, the
hydraulic capacity can be as high as 17 1/m2 per hour (28).
AS a tirst approximation, results have indicated that for
solutions containing less than 10 mg/1 total metals, 0.96 to
-J.4 kg of peat can purify 1000 liters of wastewater. Tests
the6 roces ^ that S6Veral Srades of Peat are suitable for
i-n waT£,eaPr2CeSiST is ,currently used by the Nashua Corporation
in Nashua New Hampshire, to treat a 22,700 I/day effluent
rrom the chrome plating of aluminum computer discs (29).
Applicability to Antimony Removal
Antimony removal has been demonstrated using the 75,700
I/day capacity pilot plant. After adjustment of pH in the
range of 8.0 with lime followed by settling, the wastewater
level containing 2.5 mg/1 dissolved antimony was reduced to
0.9 mg/1. Reduction of other heavy metals present in the
30
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wastewater was in all cases more effective than removal of
antimony, as indicated in Table 13.
In wastewaters with high organic content, removal with
peat is more effective. This has been borne out in the
treatment of dye house effluent, with COD of 1200 tng/1 and
BOD of 150 mg/1. Antimony was reduced from 30 mg/1 to 0.5
mg/1. Antimony in this wastewater was in solution, rather
than suspended, and removal involved chemical adsorption and
complexing (24).
Secondary Pollutants
Disposal of used peat is accomplished by burning or
landfilling. Preliminary leaching studies have indicated
that peat can be disposed of in landfills without danger of
leaching if the metal has been chemisorbed on peat as an
ion.
SODIUM BOROHYDRIDE
Process Description and Process Variables
An article in "Process Engineering," 1975, states that
the basic process of sodium borohydrate reduction is similar
to normal chemical precipitation. The treatment includes pH
adjustment, sodium borohydrate addition for reduction and
precipitation and clarification and/or filtration for
solids/liquids separation. The treated effluent may require
additional polishing with a carbonaceous adsorbent or
suitable chelate or exchange resins. The sludge contains
elemental metals which may eliminate the need for sludge
handling facilities and ultimate disposal problems can
possibly be avoided. However, if metals recovery is
desirable some sort of metal separation will be necessary
(hydro or pyrometallurgy). Sodium borohydride is a water
soluble reducing agent which can effectively reduce metals
by four possible mechanisms (30).
Reduction to a Lower Valence State This reac-
tion generally involves transition elements and
the reaction rate is limited by the rate of dis-
sociation of the borohydride ion.
Reduction to a Free Element This reaction is
typical of the heavy transition metals and often
leads to the quantitative precipitation of these
metals from solution. This reaction generally
proceeds to the intermediate formation of a metal
hydride or borohydride which is unstable in water
and subsequently decomposes to form the free
metal.
31
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TABLE 13. TREATMENT OF WASTEWATERS CONTAINING
HEAVY METALS
Case
no.
1 Pb
Sb
Cu
Zn
Ni
PH
2 Cu
Ni
Zn
PH
3 Cu
Ni
Zn
PH
4 Cr6
PH
5 Cu
Zn
Fe
Ni
CN
PH
Before
treatment
(mg/1)
20
2.5
1.0
1.5
2.5
1.6
250
67.5
7.5
2.5
26,400
5,000
10
0.1
36,000
1.5
5.0
4.6
1.0
13.5
36.0
7.75
After
treatment
(mg/1)
0.025
0.90
0.2
0.25
0.07
7.1
0.24
0.5
0.08
7.2
0.24
0.5
0.16
7.2
<0.04
7.0
0.25
0.10
<0.05
0.6
0.7
8.0
EPA
limits
(mg/1)
0.05
0.2
0.5
1.0
6-8.5
0.2
1.0
0.5
6-8.5
0.2
1.0
0.5
6-8.5
0.04
6-8.5
0.2
0.5
0.5
1.0
0.03
6-8.5
Treatment
Adjustment of pH in the range
of 8.0 with lime. Settling.
Contacting with peat.
As above .
As above .
Adjustment of pH at 7.0 with
lime. Treatment with FeCl3/
Na2&. Settling contacting
with peat.
Addition of FeSO^ and Na2S.
Settling. Contacting with
peat. Further reduction of
CN to 0.03 by aeration.
32
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Formation of Volatile Hydrides -- This is the
principal reaction mechanism for heavy elements of
groups IV-A, V-A, and VI-A. Volatile hydride
formation is the reaction mechanism which would
prevail for the reduction of antimony. The reac-
tion generally requires acid conditions; to avoid
the competing side reaction of hydrolysis, sodium
borohydride is generally added as alkaline boro-
hydride to an acid solution.
Formation of Insoluble Borohydrides Treating of
transition metal salts with borohydrides in basic
aqueous media can lead to the formation of in-
soluble borides. This reaction is not frequently
observed, although this may be because the in-
soluble borohydrides react readily in air.
There are certain advantages to using sodium boro-
hydride for treatment of metals in place of precipitation.
Elemental metals could be recovered directly and therefore
no bulky precipitates would be generated. Furthermore,
sodium borohydride is chemically very efficient. It can
provide eight available electrons for reduction. Since one
Ib (454 g) of sodium borohydride contains 12 moles, 96
equivalent weights could be supplied by one Ib (454 g)
(31). In practice, of course, presence of other reducible
compounds may alter the required borohydride. Metal ratio
and 100 percent excess borohydride is recommended to insure
complete reduction (31). One very important variable is the
pH range. At a pH of less than 8, borohydride consumption
increases due to hydrolysis and hydrogen gas is formed,
while at a pH higher than 11, the rate of metal reduction
decreases (31).
A second important variable is the mixing efficiency.
Because sodium borohydride is generally used for treatment
of low levels of dissolved metals, efficient mixing with the
stream is essential. In continuous processing, it is recom-
mended that sodium borohydride be metered into a waste
stream through a mixing tee (31).
State of the Art
The sodium borohydride system has been commercially
proven for mercury removal in chlor-alkali plants and mer-
cury processing plants. Soluble inorganic mercury compounds
are reduced at pH 9 to metallic mercury by carefully meter-
ing the required amount of sodium borohydride directly into
33
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the effluent stream. One gram of NaBH/ successfully reduces
21 grams of mercury (30,31). ^
Another commercial application which has been realized
1SA th*L removal of dissolved lead compounds from wastewater
and effluents generated in the manufacture of tetra-alkyl-
lead. Treatment of these waste streams produces a precipi-
e which may be separated by filtration or settling
, j J. ) .
A third area of application which proves the effective-
ness of the NaBH, process is the quantitative recovery of
silver from photographic fixing solutions by reducing it to
the free metal (30) .
For each specific application of NaBH/, several var-
iables should be examined, as they influence the final
product. These include pH, temperature, redox potential,
and the order of addition of acid, base, and NaBH/ .
Sodium borohydride is available through the Ventron
Corporation as a 12-percent solution of sodium borohydride
in caustic soda, and as hydroscopic sodium borohydride
powder or pellets (32). The advantage of the solution is
that it is of low viscosity, easy to handle, and already
basic in nature.
Applicability to Antimony Removal
As has been mentioned, antimony reacts with sodium
borohydride to yield the corresponding volatile hydrides.
btibine can be obtained by the dropwise addition of alkaline
Doronydnde solution of antimonite to aqueous acid. Assum-
ing that all four hydrogens of the borohydride ion are
available for hydride formation, the equation would be:
3BH' + 4H3Sb03 + 3H+ = 3B(OH>3 + 3H20 + SbH3
Application of sodium borohydride for antimony removal
has been demonstrated in the manufacture of ethylene glycol
Antimony is a contaminant of ethylene glycol and can be
removed effectively using sodium borohydride (Personal
communication: Mr. Douglas Littlehale, Ventron Corporation).
Ventron, however, has not had the same success in treating
antimony in wastewater. Although quantitative information
is not available, antimony cannot be removed as effectively
from wastewater as it can from ethylene glycol using the
sodium borohydride process. More research is needed on the
reasibility of sodium borohydride for antimony removal.
34
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Secondary Pollutants
There is a potential for the release of hydrogen gas
resulting from hydrolysis of aqueous borohydride solution.
This problem can be minimized in properly designed systems
by venting correctly and assuring the absence of external
ignition sources.
35
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SECTION 6
COST AND FEASIBILITY ANALYSIS
SUMMARY
The five antimony removal technologies discussed in
Section 5 were analyzed, as described in this section, for
overall potential for removing antimony from mining industry
wastewaters to the desired minimum levels. Through use of
evaluation techniques described later in this section, it
has been determined that the two most promising technologies
for removing antimony to a level of less than 0.5 mg/1 are
ion exchange and insoluble starch xanthate. In overall
feasibility rating, none of the other technologies approaches
these^two. The relatively high rating for these two tech-
nologies follows from a combination of high technical
probability of successful application and fairly low costs
as compared with the values for carbon adsorption, sodium
borohydride treatment, and peat moss adsorption.
Carbon adsorption and sodium borohydride technologies
have rather low ratings due to a combination of fairly high
treatment costs and relatively low technical probabilities
based on reported questionable performance and/or problems
such as pH requirements.
Peat moss adsorption has the highest estimated cost of
the five technologies, combined with the lowest technical
probability. The low technical probability is based pri-
marily on ambiguous and questionable performance reported in
the available literature.
In order to keep ion-exchange and insoluble starch
xanthate removal technologies in perspective, however, it
should be emphasized that:
As removal technologies for antimony, both ion
exchange and insoluble starch xanthate are still
in the research laboratory stage, and only a small
amount of work has been done at this level.
36
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Down to a level of approximately 1.0 mg/1 residue
antimony concentration, lime precipitation has
been widely demonstrated to be the most practical
and economical antimony removal technology.
Both ion exchange and insoluble starch xanthate
antimony removal technologies should be considered
as polishing operations to remove most of the last
mg/1 of antimony remaining after other treatment.
Other antimony removal or control technologies
such as zero discharge, recycle, water reuse,
process stream segregation, and solar evaporation
are often feasible in individual mining wastewater
situations. These options should be explored
prior to turning to the technologies evaluated in
this section.
INFLUENCING PARAMETERS
The parameters or factors that determine the applica-
bility of pollutant removal technologies to wastewater
streams are both numerous and interactive. These factors
must be considered for analyzing the cost and feasibility of
different antimony removal technologies as applied to anti-
mony-containing wastewaters from the mining industry. The
following discussion covers the pertinent parameters in-
volved in the removal process. No attempt has been made to
address the sludge removal and disposal problem.
The parameters may be divided into three categories:
(1) Wastewater-related
(2) Technology-related
(3) Plant-specific.
Wastewater-Related Parameters
Wastewater-related parameters include the volume of the
stream and its composition.
Volume--
The cost of most antimony removal technologies depends
heavily on the volume of water to be treated. The above
relationship can be expressed as an equation of the form:
K(V)
x
37
-------
where C - The cost in dollars
K = A constant specific to the technology
V = Volume of wastewater stream
x = An exponent ranging from 0.5 to 1.0, depending
on the technology.
In the above equation, for technologies where capital
equipment is the major cost component, x usually ranges from
0.6 to 0.8. In cases where material costs (such as for lime
or other treatment chemicals) predominate, x usually ranges
from 0.8 to 1.0.
The cost-volume relationship makes almost any techni-
cally feasible removal technology usable for very small-
volumed wastewaters, but narrows the practical selection
available as the volume increases.
Composition--
The effects of the composition of the wastewater stream
on the feasibility and cost of antimony removal technologies
are more complex than the cost-volume relationships. Gen-
erally these effects may be related to:
(1) Antimony concentration
(2) Antimony form
(3) Other materials present.
Antimony concentration--Most of the antimony concentra-
tions founain~~mTnTng~Tn3us"try wastewaters, particularly
after lime treatment for removal of other metals, are less
than 2 to 3 mg/1. Two counteracting factors are involved at
this concentration level. The favorable factor is that a
wide range of antimony removal technologies are economically
feasible. Adsorptive technologies such as ion exchange and
activated qarbon treatment, for example, often become more
economically practical as the amount of material to be
adsorbed decreases. Chemical treatments are also economi-
cally feasible because of the small amounts of chemicals
required to react with the antimony present. On the other
hand, as the antimony concentration decreases, the removal
efficiency often decreases as well. As an example, antimony
precipitation with chemicals such as lime and sulfide may be
Yery ?ffective in reducing the concentration of antimony
from 100 mg/1 to 2 to 3 mg/1 (97 to 98 percent removal) in a
given wastewater, but as the solubility limits of antimony
hydroxides and sulfides are approached, such as for a 2 mg/1
antimony-containing wastewater, only 0 to 5 percent removal
may be achieved. At low concentrations interference from
other ions, chelating agents, and complexing chemicals must
38
-------
be considered, as should precipitation kinetics and adsorp-
tive effects.
Antimony form--Although the physical and chemical form
of a pollutant present in wastewater should be identified
prior to any removal technology consideration, this is not
always the case. Almost all analytical data on antimony in
mine wastewater is reported on a "total" basis that includes
both suspended and dissolved portions. Particularly in the
range of 1 to 2 mg/1 metal concentration, the physical form
in which the metal exists is all-important in determining
the treatment required. Often simple filtration will reduce
the "total" metal content from an initial 1 to 2 mg/1 level
to 0.5 mg/1 or less. This reduction indicates that much of
the initial "total" metal was in the form of finely divided
suspended solids. A second concern is the chemical form of
the metal present in the wastewater. In many cases the
metal may be present as an insoluble inert component of rock
or earth particles. In other cases, it may be present in a
relatively soluble and reactive chemical form, or in the
form of a complex or chelate.
Other materials--Mining industry wastewaters contain a
wide variety of metallic compounds as well as nonmetallic
materials. The concentration of antimony is often much
lower than that of several other toxic metals which have to
be removed. Therefore, any overall treatment processes have
to address removal of both antimony and the other toxic
metals. In many cases this removal will require a multi-
stage treatment, of which lime precipitation constitutes the
first stage.
The presence of other metals and nonmetals in antimony-
containing mining industry wastewaters must be taken into
account for several reasons, including:
(1) The other metals and nonmetals may interfere with
antimony removal performance. Antimony may form a
complex or chelate with one or more of the other
materials present. Bulky precipitates of other
metals may make filtration difficult.
(2) Chemicals used to precipitate antimony may react
with and precipitate other metals as well. This
will require significantly more of the chemical
than is needed for antimony removal alone and will
increase the treatment costs accordingly.
39
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Technology Factors
In determining the applicability of technologies for
antimony removal from mining industry wastewater, there are
a number of factors which must be considered, including:
(1) Pollutant removal level required
(2) State of development
(3) Equipment required
(4) Materials required
(5) Specificity
(6) Sensitivity to interferences.
Pollutant Removal Level Required--
Antimony is removed from mining industry wastewater to
the level of 1 to 2 mg/1 by means of lime precipitation. It
is not possible to achieve lower concentrations with this
technology alone. Therefore, if antimony must be removed to
the 0.1 to 0.5 mg/1 level, lime precipitation is not appro-
priate. On the other hand, distillation could readily
achieve the 0.1 to 0.5 mg/1 residual antimony level but
would be very expensive. The removal technology must be
capable of achieving the desired level at a practical cost.
State of Development--
The state of development is an important factor in
selecting applicable antimony removal technology. Techno-
logies that have been known for years and are still labora-
tory curiosities are probably not practical and, at best,
will require extensive effort to move them to demonstration
status. Technology demonstrated on the wastewaters of other
industries usually has a much better potential for success,
but there have been many instances where the transfer from
one industry to another has caused unexpected problems.
Equipment Required--
Capital investment cost to install treatment equipment
is always a factor to be considered. In addition to the
capital costs, however, consideration also should be given
to operation and maintenance.
Materials Required--
When chemicals are used as precipitants, adsorbents, or
reactants in antimony removal technologies, the costs for
these materials often constitute the major expense involved.
Moreover, the material costs are often directly proportional
to the amount of antimony to be removed.
40
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Specificity--
Some removal technologies are more specific than others
with regard to their ability to remove only the desired
pollutant. Fortunately, most antimony removal technologies
are not very specific and will remove other metals as well.
Sensitivity To Interferences
One of the major difficulties with many pollutant
removal technologies is that some component of the waste-
water interferes with the desired removal performance.
Distillations, reverse osmosis operations, adsorptions, and
other removal technologies often require major wastewater
pretreatment. Failure to provide this pretreatment leads to
plugging, corrosion, or fouling of the equipment. Other
materials present may also change solubility, reactivity,
and settling characteristics.
Plant-Specific Factors
In addition to the more general wastewater and tech-
nology factors, there are others of a more site- or plant-
specific nature. These factors depend on special circum-
stances such as:
(1) The process used
(2) Value of the product produced
(3) Waste recovery value
(4) Reuse capabilities
(5) Geographic location and topography.
The Process Used--
Different processes may be used to produce the same
end product. The wastewater from each process is usually
specific, differing significantly in both volume and com-
position from those of other processes.
Value of the Product--
In order to estimate the economic impact of installing
pollutant removal technology on a plant or industrial sub-
category, calculations are usually made of the costs per
unit of product and/or costs as a percentage of selling
price. A cost increase of $1 per metric ton of produced
silver is likely to have a significantly different impact
than would a similar increase for a metric ton of sand or
gravel.
41
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Waste Recovery Value--
In some instances, the wastewater to be treated con-
tains valuable materials which can be recovered and sold or
reused. Prime examples are wastewaters containing gold or
silver. The value of the recovered gold or silver can
underwrite the development and use of complex technology and
expensive treatment systems that would not otherwise be
practical.
Reuse Capabilities--
Reuse of components of the wastewater stream can be
applied either to the water or to the materials recovered
from it. As the availability of water decreases and its
price increases, more and more attention is being given to
its recycle and reuse. Recycle and reuse not only make more
complex treatment technology economically feasible, but also
constitute one of the more desirable forms of pollutant
control in that there is no discharge from the plant en-
virons .
Geographic Location and Topography--
Plant-specific factors such as geographical location
and local topography may have pronounced effects on the cost
and feasibility of wastewater treatment technology. For
example, in dry climates solar evaporation may be feasible.
It is not practical in areas with heavy rainfall. In other
cases, plants may be located on small urban plots with no
room for settling ponds or other large-area treatment facil-
ities. In hilly or mountainous terrain wastewater may be
dammed in valleys and stored, percolated, or evaporated at a
fraction of the treatment costs for flat-land installations.
FEASIBILITY METHODOLOGIES
The parameters influencing cost and feasibility of re-
moving antimony from wastewater need to be considered in a
systematic, objective fashion.
Feasibility Parameters
Feasibility of antimony removal technology first de-
pends on whether the desired removal level can be reached.
For purposes of this study, the inherently achievable level
of residual antimony must be less than 0.5 mg/1. Unfortun-
ately, for most technologies, information on antimony re-
moval at this level is usually not available. Therefore,
when there is a reasonable possibility that a technology
will remove antimony to the 0.1 to 0.5 mg/1 level, this
technology has been included for consideration.
42
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The second feasibility concern is technical applica-
bility. Applicability includes such factors as considera-
tion of the physical and chemical form of the antimony
present, the state of development of the removal technology,
industry demonstration, sensitivity to interference, space
requirements, availability of equipment and materials, and
geographical location. A simple example of inapplicable
technology would be the use of filtration equipment to
remove dissolved antimony. On the other hand, filtration
could be a perfectly applicable technology to remove sus-
pended antimony-containing particles. For purposes of this
study, only dissolved antimony removal technology is con-
sidered.
The third feasibility concern is economic impact - the
influence that the given antimony removal technology will
have on the profitability and viability of the mining opera-
tion. No attempt is made in this study to estimate the
profitability of the mining operations or the influence on
this profitability of installing and operating antimony
removal technology. Rather, the antimony removal costs are
presented in the form of percent of sale values of the mined
product(s). For example, if the total annual antimony
removal technology cost is $10,000 and the total value of
the mined and recovered products is $1,000,000 per year,
then the cost would be one percent of product value.
Calculating antimony removal technology cost is not a
simple matter. For accurate estimates, each mining opera-
tion needs to be considered individually. For rough esti-
mates, however, assumptions may be made which will simplify
these calculations. Factors which have significant influ-
ence on the costs of antimony removal technologies include:
(1) Research and development costs
(2) Required capital equipment and auxiliary ser-
vices
(3) Operating materials and labor.
Feasibility Index
The'feasibility index developed by Hittman for use in
this study is composed of two factors: the probability of
successful technology development and the cost impact This
index was used in an attempt to eliminate bias and provide
a method of analysis.
The cost impact estimation used for this study has been
discussed previously. The probability of successful
43
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technology development is composed of four factors as de-
fined below:
P = (L) (A) (S) (R)
where P = The probability of successful technical
development
L = The probability of achieving the desired
removal level, based on theoretical param-
eters such as inherent solubility
A = Availability of equipment and materials, ex-
pressed as a probability between 1.0 and 0
S = The sensitivity of the technology to inter-
ferences from wastewater constituents other
than antimony, expressed as a probability,
with 1.0 representing no interference and
0 representing interference so serious as to
make the technology useless
R = The probability of successful research and
development efforts overcoming existing prob-
lems
The values of L, A, S, and R given for the various antimony
removal technologies evaluated later in this section were
arrived at by consensus of the two members of the team pre-
paring this report who are most familiar with the available
data on antimony removal from water media.
Using the above probability of successful technical
development together with the cost impact, the feasibility
index is defined as:
'§
where: F - The feasibility index
C = The cost impact expressed as cost percentage
of product value.
The feasibility index defined above can be used to
provide a rough comparison of the applicability of given
technologies for antimony removal and may also be used with
increased precision as additional information is obtained
through laboratory, pilot plant, and other applied tech-
nology evaluation techniques.
44
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TECHNOLOGY ANALYSES
In order to assess the technical and economic feasi-
bility of antimony removal technologies, it is necessary to
establish some basis for technology requirements and cost
estimating. Therefore, the following values have been
selected for use in all calculations:
Parameter Value
Wastewater volume 3,785 m3/day
Mine product value $10,000,000/yr
Wastewater composition
Total suspended solids 20 mg/1
Dissolved antimony 3 mg/1
Total dissolved heavy 10 me/1
metals
Although the chosen values for the above parameters do
not represent the actual values at any given mine, they can
be used for feasibility calculations, particularly for
comparison purposes. Using the above parameter values,
feasibility indices have been determined for the five poten-
tially usable antimony removal technologies discussed in
Section 5.
With the exception of the values for peat moss adsorp-
tion technology, which were taken from a published article,
all capital costs for treatment equipment installations have
been estimated with the additive modular approach, using
cost-capacity curves as described in Reference 33. Unless
ptherwise stated, operating costs were either taken from
Reference 33 or estimated using procedures described in
Reference 34. Both capital costs and operating costs should
be considered order-of-magnitude numbers, with an accuracy
of + 50 percent.
Ion Exchange Technology
Ion-exchange resins have been used to remove antimony
from water and water-ethylene glycol mixtures in laboratory
and pilot plant experiments. There is no information on the
removal levels achieved.
45
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Technical Probability--
The technical probability index for antimony removal
technologies and the method used to arrive at the individual
probability values were described in the preceding section.
The technical probability index was defined as P=(L)(A) (S) (R)
Values of L, A, S, and R for ion-exchange removal of anti-
mony are estimated as:
L = 0.8 S = 0.5
A = 0.9 R = 0.7
Using these probability values:
P=0. 8x0. 9x0. 5x0. 7 =0.25.
Cost Index- -
2 The estimated installed capital costs for a 3,785
m /day continuous countercurrent ion-exchange facility are
approximately $150,000 (1972 base) (33). Adjusting this
value to July 1978 prices using the Chemical Engineering
Plant Cost Index,
1978 Cost = $150,000 x = $237,600.
Estimated operating cost for 10 mg/1 removal of antimony and
other heavy metals is approximately $.026/nT or $36,000 per
year.
Amortizing the capital costs of the facilities over a
10-year life at 10 percent interest rate,
Annual Capital Cost = $237,600 x .1627 = $38,660.
The total annual cost, therefore, for both capital
amortization and operation is $74,680. Dividing this by the
product value of $10,000,000 per year gives:
Cost index =
_
0,000,000
Feasibility Index--
The feasibility index for ion-exchange removal of
antimony from mining wastewater is:
F - p - °'25 - n QI
* ~ C - OT75 * °'33-
46
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Activated Carbon Adsorption
Activated carbon is reported to remove antimony from
water in the laboratory. According to one source, the
recommended pH for removal is approximately 1, which re-
quires that significant quantities of acid be added to the
wastewater prior to removal (24). This cost has not been
included in determining the cost index, since others have
not reported this requirement (13).
Technical Probability--
Values of L, A, S, and R and the resulting technical
probability index are given below:
L = .5
A = .9
S = .7
R = .5
f = .5 x .9 x .7 x .5 = 0.16.
Cost Index- -
Estimated installed capital cost for a 3,785 m3/day
facility is $700,000 (1973 base) (33). Adjusting this value
to July 1978 prices using the Chemical Engineering Plant
Cost Index,
1978 cost = $600,000 x = $1,050,000.
Taking estimated operating costs for 10 mg/1 removal of
antimony and other heavy metals from Reference 33 and ad-
justing them for increased energy and labor costs from 1974
gives approximately $0.026/m or $36,000 per year.
Amortizing the capital costs of the facilities over a
10-year life at 10 percent interest rate,
Annual capital cost = $1,050,000 x .1627 = $170,835.
The total annual cost, therefore, for both capital
amortization and operation is $206,835. Dividing this total
by the product value of $10,000,000 per year gives
Post inripv - $206,835 v i no - o r»7
oost index - $10, 000, 000 x 10° ~ 2'07'
47
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Feasibility Index--
The feasibility index for carbon adsorption removal of
antimony from mining wastewaters is:
F - p - Q-16 - ns
* " C ~ 270T ~ '°8
Insoluble Starch Xanthate
The use of insoluble starch xanthate to reduce antimony
concentration below 0.5 mg/1 has been reported from two
sources (Personal communications: Mr. John Bell, Mogul
Corp., and Mr. John Zschiegner, J&J Materials). Both
sources are based on actual laboratory experiments designed
for antimony removal.
Technical Probability--
The values of L,A,S, and R for insoluble starch xan-
thate removal of antimony are estimated as:
L = .9
A = .9
S = .8
R = .7
P = .9 x .9 x .8 x .7 = .45.
Cost Index--
The major capital equipment items needed for use of
insoluble starch xanthate treatment of 3,785 m /day of
wastewater are:
(1) ISX feed system
(2) Reaction vessel
(3) Clarifier
(4) Centrifuge or filter.
Installed capital costs (1973 base) (33) are:
ISX feed system $ 30,000
Reaction vessel 25,000
Clarifier 85,000
Centrifuge or filter 40,000
TOTAL $180,000
Converting this cost to July 1978 dollars,
1978 cost = $180,000 x = $269,400.
48
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The annual amortized cost, taken as 10-year life and 10
percent cost of money, is $2,691,400 x .1627 or $43,830.
With the exception of the chemical cost for the 1SX,
operating costs for the above equipment should be similar to
those for other water treatment systems using chemical feeds,
reactors, clarifiers, and filters or centrifuges.
Estimated operating costs are (34):
Operating Costs (Excluding Chemicals)
Operating labor and supervision at 4% of $10,776
capital costs
Maintenance, labor and materials at 3% of 8,082
capital costs
Analytical services at 1% of capital costs 2,694
Utilities at 3% of capital costs 8,082
General overhead at 2% of capital costs 5,388
Insurance and taxes at 3% of capital costs 8,082
TOTAL $43,104
Chemicals
The major chemical expense is for ISX. Taking a manu-
facturer-recommended dosage of 50 mg/1 for removing 5 mg/1
of antimony to a level of 0.01 mg/1 (reported laboratory
performance of antimony removal by Mr. John Zschiegner, J&J
Materials) as the basis for chemical usage gives:
ISX required = J^ffi x 3.785.000 liters x 365 days
= 68,985,000 £ or 68,985 kg/yr
49
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ISX cost/yr » $68,985 x 0.77* = $53,100-
The total annual cost of ISX removal of antimony is
estimated as $96,200 + $43,800 or $140,000. Dividing this
total by the product value of $10,000,000 per year gives:
- 1.40.
Although the cost of $0.77 per kg for ISX has been used
in the preceding calculations, with the justification that
such a large usage would warrant preparation in the plant,
ISX is commercially available at $17.60 per kg. The deci-
sion for making or buying would have to be made on the basis
or cost efficiency.
Feasibility Index- -
The feasibility index for insoluble starch xanthate
removal of antimony from mining wastewater is:
Feat Moss Adsorption
Various natural organic materials such as chit in, peat
moss, and other humic substances have been used to adsorb
heavy metals dissolved in wastewater. Peat moss adsorption
systems have been developed on pilot-plant and commercial
scales, and are discussed in detail in Section 5. Only
sketchy and somewhat contradictory information has been
reported on the performance of these systems for antimony
J
removal .
Technical Probability--
Values of L,A,S, and R and the resulting technical pro
ability index are given below:
L - 0.3
A - 1.0
S - 0.6
R - 0.3
P - 0.3 x 1.0 x 0.6 x 0.3 - 0.05.
nf l°l 'ty* 8,ed °n U8er makin9 own ISX (cost supplied by
?Lrf'ff;/T; Vi'S' ^^ItuTal Research Laboratories).
$43 100 +'ts* "tnn^^l °P'***8 *<>** estimated at
^^^tiuu + $>53jlOO or $96f200.
50
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Cost Index--
According to Reference 29 the installation costs of a
peat moss adsorption system for treating 3,785 m3/day of
wastewater are $600,000 (1974 base). Adjusting this to a
1978 cost basis using the Chemical Engineering Plant Cost
Index, gives:
1978 cost = $600,000 x = $789,000.
Amortizing this cost over a 10-year period at an interest
rate of 10 percent gives:
Annual Capital Costs = $789,000 x .1627
= $128,370.
Operating costs for a peat moss system may be estimated
using Reference 34 for calculating operating costs exclusive
of peat moss and adding the peat moss costs to this value.
Operating Costs (Excluding Peat Moss)
Operating labor and supervision at 4% of $ 31,560
capital costs
Maintenance, labor, and materials at 3% 23,670
of capital costs
Analytical services at 1% of capital 7 890
costs '
Utilities at 3% of capital costs 23,670
General overhead at 2% of capital costs 15,780
Insurance and taxes at 3% of capital 23 670
costs '
TOTAL $126,240
i /i A requfrements are roughly estimated at 1.2
kg/1,000 liters or 4.5 metric tons per day (4) At a
delivered price of $50 per metric ton, the annual costs for
peat moss are:
51
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Peat moss costs = 4.5 %& x ^S.dajr $50
day yr ' kkg
= $82,125.
Therefore the tota] annual operating costs are $82,125 +
$126,240 or $208,365.
The total annual cost of peat moss removal of antimony
is estimated as $208,365 + $126,240 or $334,605.
Dividing the above total by the product values of
$10,000,000 per year gives:
Cost Index = $^4,605 x IQQ = o oc
$10,000,000 1U J.JJ-
Feasibility Index--
The feasibility index for peat moss removal of antimony
from mining wastewaters is:
F - P _ 0.05 _ « A1
F ' C ~ 1715 - °-01-
Sodium Borohydride Precipitation
Sodium borohydride has been used to remove dissolved
heavy metals such as mercury from industrial wastewaters,
achieving residual metal levels of less than 0.1 mg/1 (Per-
son.il communication: Mr. D. Littlehale, Ventron Corpora-
i^/wln' ExPerimental results reducing antimony levels from
1,000 mg/1 to less than 2 mg/1 have been achieved in glycol-
water mixtures (Personal communication: Mr. M. Cook, Ventron
Corporation). It is also believed that significantly lower
residual concentrations should be achievable, particularly
when starting with more dilute concentrations of antimony
ion (Personal communication: Cook).
Technical Probability--
The values of L,A,S, and R for sodium borohydride
removal of antimony are estimated a.s:
L = 0.6
A = 1.0
S = 0.6
R = 0.5
P = 0.6 x 1.0 x 0.6 x 0.5 = 0.18.
52
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Cost Index--
Removal of dissolved antimony from wastewaters with
sodium borohydride requires a chemical storage and feed
system, reaction and decanting vessels, and polish filtra-
tion to remove residual suspended antimony particles.
The estimated capital costs for a 3,785 m3/day waste-
water treatment system are shown below (33,35):
Installed Costs
Equipment (1973 base)
Storage and feed system $ 30,000
Reaction vessel 25,000
Decanting vessel 25,000
Sand filter system 100,000
Total $180,000
Converting this cost to July 1978 dollars gives:
1978 cost = $180,000 x = $269,400.
The annual amortized cost, taken for 10-year equipment life
and 10 percent cost of money, is $269,400 x 0.1627 or
$43 , 830 .
With the exception of the cost for sodium borohydride,
operating costs for the above equipment should be similar to
those for other water treatment systems using chemical feed
systems, reactors, settling vessels, and filters. Therefore
operating costs may be estimated from a combination of
operating costs exclusive of chemical costs and sodium
borohydride costs.
Operating costs excluding sodium borohydride are sim-
ilar to those previously calculated for the ISX system, or
$43,104.
Sodium borohydride costs, based on values supplied by
personal communication with Mr. Michael Cook of the Ventron
Corporation, follow.
Basis for calculation:
(1) 3 moles of sodium borohydride react with 8 moles
of Sb (3).
53
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(2) Four times excess will be required.
(3) A total dissolved heavy metal content equivalent
to 10 mg/1 of Sb is present in the wastewater (3).
Sodium borohydride =
x .
x 3,785 m3/day x 365 days/yr
x 1 kg/1,000 g
= 6,440 kg/yr,
Sodium borohydride cost = 6,440 kg/yr x $33/kg = $212,920,
Total annual operating cost = $212,920 + $43,100
= $256,000.
Adding the amortized annual capital equipment costs to
the annual operating costs gives a total operating cost of
$256,000 + $43,830 or $299,830.
Dividing the total annual cost by the product value of
$10,000,000 per year gives:
Cost Index = ^9.830^ x 100 = 3<()
Feasibility Index- -
The feasibility index for sodium borohydride removal
ol antimony -from mining wastewater is:
P _ P _ 0.18 _ n A<.
F ~ c -
Di scussion of Values
The feasibility, cost, technical probability indices
and the L, A, S, and R components of the probability indices
for the five antimony removal technologies analyzed in this
section are summarized in Table 14, along with those for a
sixth removal technology, distillation.
54
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TABLE 14. SUMMARY OF PROCESS APPLICABILITY ESTIMATES
FOR ANTIMONY REMOVAL
Technology
Ion exchange
Insoluble starch
xanthate
Carbon adsorp-
tion
Sodium
borohydride
Peat moss
adsorption
Distillation
F
0.33
0.32
0.08
0.06
0.01
0.05
C
0.75
1.40
2.07
3.0
3.35
13.81*
P
0.25
0.45
0.16
0.18
0.05
0.64
L
0.8
0.9
0.5
0.6
0.3
1.0
A
0.9
0.9
0.9
1.0
1.0
1.0
S
0.5
0.8
0.7
0.6
0.6
0.8
R
0.7
0.7
0.5
0.3
0.3
0.8
*Calculated from a cost estimate of $l/m3 of wastewater
distilled.
P = (L) (A) (S) (R)
where: P = The probability of successful technical
development
L = The probability of achieving the desired
receival level, based on theoretical parameters
such as inherent solubility
A = Availability of equipment and materials,
expressed as a probability between 1.0 and 0
S = The sensitivity of the technology to interfer-
ences from wastewater constituents other than
antimony, expressed as a probability, with 1.0
representing no interference and 0 representing
interference so deviant as to make the tech-
nology useless.
R = The possibility of successful research and
development efforts overcoming existing problems.
F = P
C~
F = The feasibility index
C = The cost impact expressed as cost percentage of
product value.
55
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Distillation has been included to illustrate the
interactions that make the feasibility index a significant
overall rating mechanism. Distillation's high values of 1.0
for L and A indicate that theoretically distillation can
remove antimony to less than 0.5 mg/1 and that equipment
exists to carry out such distillations. The 0.8 probability
ratings for S and R indicate that although interferences and
R&D problems can most likely be overcome, some significant
problems exist with pretreatment, corrosion, fouling, and
handling of high solids residues. The technical probability
index, calculated from L, A, S, and R values, is still very
high compared to those for the other five technologies.
Estimated cost values for distillation, on the other hand,
are roughly ten times those for ion exchange and insoluble
starch xanthate removal technologies. In overall feasi-
bility, therefore, distillation rates relatively low as an
antimony removal technology for mining industry wastewater.
The overall feasibility index values indicate that ion
exchange and insoluble starch xanthate technologies have a
definitely higher probability of successful application for
antimony removal than any of the other four. Carbon ad-
sorption, sodium borohydride treatment, and distillation
have only scant probability of successful application and
peat moss adsorption falls at the bottom of the probability
rating.
56
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REFERENCES
1. U.S. Environmental Protection Agency. Literature Study
of Selected Potential Environmental Contaminants.
Antimony and its Compounds.EPA-560/2-76-002, February
1976.
2. Ralph Stone and Co., Inc. Treatment Effectiveness for
the Removal of Selected Contaminants from Drinking
Water.Prepared tor the U.S. Environmental Protection
Agency, March 1975.
3. U.S. Environmental Protection Agency. Development Docu-
ment for Interim Final and Proposed Effluent Limita-
tlons Guidelines and New Source Performance Standards
for the Ore Mining and Dressing Industry.EPA 440/1-
75/061, C-ctober 1975.
4. Leslie, M.E., "Peat: New Medium for Treating Dye House
Effluent." American Dyestuff Reporter. August 1974,
pp. 15-18. K
5. R.K. Guthrie and D.S. Sherry. "Pollutant Removal from
Coal-Ash Basin Effluent." Water Resources Bulletin,
Vol. 12, No. 5, pp. 889-903"!
6. M.L. Hemming. "Effluent Treatment in the Paint and
Surface Coating Manufacturing Industry." Paint Manu-
facture. June 1975, pp. 8-29.
7. Roy E. Williams, et al. The Role of. Mine Tailings
Ponds in Reducing the Discharge of Heavy Metal Ions to
the Environment. Moscow; Idaho Bureau of Mines and
Geology, 1973.
8. Calspan. Chemical Analysis Data Supplement to the
Addendum to Development Document for Effluent Limita-
tions Guidelines and Standards of Performance for the
Ore Mining and Dressing Industry.Prepared for the
U.S. Environmental Protection Agency, May 1978.
9. R.S. Ottinger, et al. Recommended Methods of Reduc-
tion. Neutralization, Recovery or Disposal of Ha'zard-
ous Wastes. Vol. 12. U.S. Environmental Protection
Agency 670/2-73-0531, August 1973.
57
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10. U.S. Environmental Protection Agency. Draft and New
Data for the Development of Effluent Limitations Guide-
lines for the Miscellaneous Nonferrous Metals Segment"
of Nonferrous Metals.EPA-440/1-78/067, January 1978.
11. Sunshine Mining Company. National Pollutant Discharge
Elimination System.- Discharge Monitoring Reports,
Kellogg, Idaho, Sunshine Mining Company, 1978.
12. STORET Retrieval Data. USEPA Region X. Pacific North-
west, Spokane River Basin, 1119C050.
13. Hannah, A., M. Jelus, J.M. Cohen. "Removal of Uncommon
Trace Metals by Physical and Chemical Treatment Proc-
esses." Journal of the Water Pollution Control Federa-
tion. November 1977, pp. 2297-2309.
14. Cotton, F.A. and G. Wilkinson. Advanced Inorganic
Chemistry. Interscience Publisher, 1966, pp. 486-518.
15. Stumm, W. and J.J. Morgan. Aquatic Chemistry: An
Introduction Emphasizing Chemical Equilibria in "Natural
Waters, New York: Wiley-Interscience, 1970, pp. 238-
^ .7 I/
16. Permutit Company. Proceedings of Seminar on Metal
Wastes Treatment Featuring the Sulfex ProceslTParamus:
Permutit Company, 1975.~~
17. Dean, J.G., F.L. Bosqui and K.H. Lanouette. "Removing
Heavy Metals from Wastewater." Environmental Science
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18. Calmon, C. "Trace Heavy Metals in Water: Removal Pro-
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ronmental Protection Agency, EPA-902/9-74-001, 1973
pp. 7-42. '
19. Wheaton, R.M. and A.H. Seamster. A Basic Reference on
Ion Exchange. The Dow Chemical Company, 1977pp871-
«yy.
20. Kunin,(|R. "Ion Exchange for the Metal Products Fin-
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21. U.S. Environmental Protection Agency. Treatment Effec-
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Stone and Company, Inc., 1975, p 111-15
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22. Wing, R.E. "Processes for Heavy Metal Removal from
Plating Wastewaters." Presented at: American Society
of Electroplated Plastics, 10th Annual Meeting, San
Diego, November 16-19, 1977.
23. U.S. Department of Agriculture. Insoluble Starch Xan-
thate: Preparation and Use in Heavy Metal Removal.
CA-NRRC41 (Rev. 2).Peoria: Northern Region Research
Center, June 1976, pp. 1-7.
24. ICI United States, Inc. Activated Carbon in the Metals
Industry. Wilmington: Specialty Chemicals Division,
1976, pp. 1-8.
25. Smith, S.B. "Trace Metals Removal by Activated Car-
bon." In: Traces of Heavy Metals in Water Removal
Processes and Monitoring. EPA-902/9-74-OQ1.New"
York's U.S. Environmental Protection Agency, 1973, pp.
55-70. V
26. ICI United States, Inc. Chemicals for the Metals
Treating Industry. Wilmington: ICI-Specialty Chemicals
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27. Sigworth, E.A. "Potentialities of Activated Carbon in
the Metallurgical Field." In: AIME Proceedings. New
York: American Institute of Mining, Metallurgical, and
Petroleum Engineers, 1962.
28. Coupal, B. and J. Lalancette. The Treatment of Waste
Waters with Peat Moss. Cornwells Heights: Hussong-
Walker-Davis Company, 1975.
29. Krewson, W.G. "Heavy Metal Removal with Sphagnum
Peat." Presented at American Institute of Chemical
Engineers Symposium, Atlantic City, 1976.
30. Ventron Corporation, Inorganic Reductions with Sodium
Borohydride: Principles and Practices.Beverly: Ven-
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31. Ventron Corporation. Heavy Metal Recovery with Sodium
Borohydride. Beverly:Ventron Chemicals Division,
Technical Bulletin #47-A. n.d.
32. Ventron Corporation, A Stabilized Water Soluble Solu-
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33. U.S. Environmental Protection Agency, Development Docu-
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34. Parker, C.L. and C.V. Fong. "Estimation of Operating
Costs for Industrial Wastewater Treatment Facilities."
American Association of Cost Engineers Bulletin
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Sept./Oct. 1975, pp. 6-7. *
60
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/7-79-129
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Antimony Removal Technology for Mining
Industry Wastewaters
5. REPORT DATE
May 1979
issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
C. Leon Parker, Efim Livshits, and
Kathleen McKeon
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Hittman Associates/ Inc.
9190 Red Branch Road
Columbia, Maryland 21045
10. PROGRAM ELEMENT NO.
1NE623B
11. CONTRACT/GRANT NO.
68-03-2566
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Lab.
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final 3/15/78 - 7/15/78
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report assessed the current state-of-the-art of antimony
removal technology for mining industry wastewaters. Through literature
review and personal interviews, it was found that most mines and mills
reporting significant quantities of antimony in their raw wastewater
had approximately 0.1 to 0.2 mg/1 antimony remaining after tailings
pond settling. This reduction in antimony content without any chemical
treatement indicates that for most mines and mills the antimony-con-
taining wastewater components are in the form of suspended solids and
may be easily removed.
Sulfide precipitation technology cannot remove soluble antimony
to levels below 2.0 to 3.0 mg/1 and lime precipitation cannot lower
levels below 1.0 mg/1. A minimum desired level of 0.5 mg/1 of antimony
was selected for this technology assessment based on the effluent
limitation recommended by the EPA BPCTCA in antimony mines. There is
currently no demonstrated technology for achieving this minimum desired
antimony level. Ion exchange and insoluble starch xanthate appear to
be promising technologies for antimony removal; carbon adsorption,
sodium borohydride reduction, and peat moss adsorption do not appear
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Antimony inorganic compounds
Tailings
Beneficiation
Neutralizing
Lime neutralization
Ion exchange
Insoluble starch
xanthate
Peat moss
Carbon adsorption
Drainage, mines
13B
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
71
2O. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
61
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