Alternatives for Sodium Cyanide for
Flotation Control
Battelle Columbus Labs., OH
Prepared for
Industrial Environmental Research Lab
Cincinnati, OH
Aug 81
PB81-2W39
U.1 PiiwtBiit of Commerce
Natkmil Technical Information Service
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PB81-2W39
Alternatives for Sodium Cyanide for
Flotation Control
Battelle Columbus Labs., OH
Prepared for
Industrial Environmental Research Lab
Cincinnati, OH
Aug 81
U.S. teprtMrt 0f Commerce
National Technical Information Service
urns
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing}
1. REPORT NO.
EPA-600/2-81-157
4. TITLE AND SUBTITLE
ORD Report
Alternatives for Sodium Cyanide for Flotation Control
3. RE(
5. REPORT DATE
August 1981
8. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
E. J. Mezey, D. W. Neuendorf, G. Ray Smithson, Jr,
and James F. Shea (Consultant)
8. PERFORMING ORGANIZATION REPORT Nj o
G-6617-0800
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Battelle Columbus Laboratories
505 King Ave
Columbus, Ohio 1J3201
10. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
68-03-2552
12, SPONSORING AGENCY NAME AND ADDRESS
Indusrtial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Prot.";tion Agency
Cincinnati. Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final 2/78 - 1/Bl
14. SPONSORING AGENCY CODE
EPA-600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT ~~ ' •—~
Cyanide has long been looked upon as the classical poison and has been listed by EPA as
a priority pollutant. The mineral dressing industry has long used cyanide in its con-
centration and extractive metallurgy operations. Cyanide plays a role of varying impor-
tance in the metallurgy of gold, silver, copper, nickel, cobalt, lead, zinc, molybdenum,
and cadmium. In the copper, lead, and zinc industries the primary uses for cyanides arc
as depressants for the flotation of iron and zinc minerals and for the reactivation of
copper minerals in the flotation of molybdenite.
This study was made to determine the technical, and if possible, the economic feasibilit
of substituting alternate reagents for cyanides as depressants for iron in the flotatior
of copper, lead, and zinc ores. The study was carried out in two phases. The first
consisted of a literature search, an evaluation of the data obtained in the search, ancj
finally a suite of laboratory-scale flotation experiments to test the three selected
reagents. These experiments were made on copper ores, copper-lead-zinc ores, and zinc
ores supplied by industry. The three reagents selected and tested were sodium sulfite
sodium sulfide, and sodium thiosulfate. Phase II consisted of interviewing company
officials and operators in the copper-l°ad-zinc industry. Visits were made to 11 com-
panies operating 17 mills in these fields.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Cyanide
lotation
Minerals beneficiation
ifaste treatment
rocess modification
Mining and milling wastes
lotation depressants
b.IDENTIFIERS/OPEN ENDED TERMS
C. COSATI I'lcld/Ciroup
13B
8. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (TMsRtport)
UNCLASSIFIED
21. NO. OF PAGES
JO. SECURITY CLASS (TMtpage)
UNCLASSIFIED
22. PRICE
EPA Form 7220-1 (R»v. 4-77) PREVIOUS EDITION is OBSOLE TE
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EPA Report No. EPA—600/2—81—157
January, 1981
ALTERNATIVES FOR SODIUM CYANIDE
FOR FLOTATION CONTROL
by
E. J. Mezey, D. W. Neuendorf, C. Ray Smithson, Jr.,
and James F. Shea*
Battelle Columbus Laboratories
Columbus, Ohio 43201
Contract No. 68—03-2552
Project Officer
Roger Wilmoth
Energy Pollution Control Division
Industrial Environmental Research Laboratory
Cincinnati, OhIo 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
US. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHiO 45268
*Co isu1 tant
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DISCLAIMER
This report has been reviewed by the Industrial Environmental ResearHi
Laboratory, U.S. Environmental Protection Agency, and approved for publirntio .
Approval does not signify that the contents necessarily reflect the views nnd
policies of the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or recommendatio!
fur use.
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FOREWORD
When energy and material resources are extracted, processed, 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
(IERL—Ci) assists in developing and demonstrating new and improved methodol-
ogies that will meet these needs both efficiently and economically.
This is one of a series of studies by the EPA undertaken to define data
requirements nd the research deemed essential to find an acceptable resolution
of the problem of cyanide pollution of water released from mineral flotation
processes. One approach considered here was to substitute a less toxic or
nontoxic substance for cyanide rather than find a treatment process capable oi
removing the low concentraticn. , of cyanide found in typical large—volume
discharges from froth flotation mineral beneficiation facilities.
This study was made to determine the technical, and if possible, the
economic, feasibility of substituting alternate reagents for cyanides as
depressants for iron in the flotation of copper, lead, and zinc ores. The study
was carried out in two phases. The first consisted of a literature search, an
evaluation of the data obtained in the search, selection of the three most
promising reagents indicated by the evaluation, and finally a suite of
laboratory—scale flotatior experiments to test the three selected reagents.
These experiments were made on copper ores, copper—lead—zinc ores, and zinc ores
supplied by industry. The three reagents selected and tested were sodium
sulfite, sodium sulfide, and sodium thiosulfate. When the ‘.aboratory experi-
ments indicated that these reagents did exhibit depressant potential for pyrite
flotation, possibly equal to that of cyanide (also tested in parallel
experiments), Phase II was undertaken. In the Phase 1.1 program, a stated
initial objective was to determine the technical and economic feasibility of
changing from sodium cyanide to any of the alternative reagents as pyrite
depressants. The economic situation was found to be so complex that no reliable
conclusions could be made under the scope of this effort.
If additional information is requested, please contz t the Nonferrous
Metals and Minerals Branch of the Energy Pollution Control Division.
David C. Stephart
Direc tor
Industrial Environmental Research Laboratory
Cincinnati
i-i
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ABSTRACT
This was one of a series of studies by the EPA undertaken to define data
requirements and the research deemed essential to find an acceptable resolution
of the problem of cyanide pollution of water released from udnera]. flotation
processes. One approach considered here was to substitute a less toxic or
nontoxic substance for cyanide rather than find a treatment process capable of
removing the low concentrations of cyanide found in typical large—volume
discharges from froth flotation mineral berteficiation facilities.
This study was made to determine the technical, and if possible, the
economic feasibility of substituting alternate reagents for cyanides as
depressants for iron in the flotation oi copper, lead, and zinc ores. The
study was carried out in two phases. The first consisted of a literature
search, an evaluation of the data obtained in the search, selection of the
three most promising reagents indicated by the evaluation, and fiz ally a suite
of laboratory—scale flotation experiments to test the three selected reagents,
These experiments were made on copper ores, copper—lead—zinc ores; and zinc
ores suppl ed by industry. The three reagents selected and tested were sodium
sulfite, sodium sulfide, and sodium thiosulfate.
When the laboratory experiments indicated that these reagents did exhibit
depressant potential for pyrite flotation, possibly equal to that of cyanide
(also tested in parallel experiments), Phase II was undertaken. In the Phase
II program, a stated initial objective was to determine the technical and
economic feasibility of changing from sodium cyanide to any of the alternative
reagents as pyrite depressants. It was hoped that this objective might he
realized by interviewing company officials and operators in the copper—lead—
zinc industry. Accordingly, visits were made to 11 companies operating 17
mills in these fields. The officials of four additional mills were interviewed
by phone. It became evident early in the course of this phase that the objec-
tive of determining the technIcal and economic feasibility of using alternative
reagents for cyanide could not be achieved by this procedure. The data obtained
on the mission served chiefly to show that the industry was aware of the
potential for changeover, had in some cases done some work to investigate the
possibility, was by and large skeptical about both the need for and the
feasibility of a changeover, and could provide very little information on
the technology and economics that might be ir.volved.
Phase II was then altered to being a fact—finding mission. Phase II Cu]-
mninated in a plan——a reapproach to the problem. It is believed that if the
recommendations arrived at in the Phase II program are followed out, the
initially desired objectives of Phase II can be achieved. The question, “Is
it feasible to make the changeover and, if so, what will be the cost?”, can
then be definitively answered.
iii
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INTRODUCTION
Cyanide has long been looked upon as the classical poison and has been
listed by EPA as a priority pollutant. The mineral dressing industry has long
used cyanide in its concentration and extractive metallurgy operations. Cyanide
plays a role of varying importance in the metallurgy of gold, silver, copper,
nickel, cobalt, lead, zinc, molybdenum, and cadmium. In the copper, lead, and
zinc industries the primary uses for cyanides are as depressants for the fi ta-
tion of Iron and zinc minerals and for the reactivation of copper minerals in
the flotation of molybdenite.
If environmentallY acceptable replacement reagents could be found that
were as effective as cyanide in depressing iron, then the very worthwhile
objective of eliminating a known toxic material from the environment might be
realized. To this end the EPA engaged Battelle’s Columbus Laboratories to
investigate such a possibility.
CONCLUSIONS
The Phase I work consisted of a literature review and limited laboratory
work. This research indicated that at least. three reagents of relatively low
toxicity might serve as alternatives for cyanide in the depression of iron
flotation.
The results from these preliminary screening experiments suggest that
sodium sulfide, Na 2 S, and sodium sulfit2, Na 2 SO 1 , could approach the effec-
tiveness of sodium cyanide, NaCN, as a pyrite d presaant under the constraints
of this experimental program and the ores studied. The results suggest ‘that
their use should be evaluated as an alternative to the treatment of large
volumes of mining wastewater containing low concentrations of cyanide. The
breadth of applicabi1 tY of such alternative depressants remains unknown and’
must be determined. The benefits of reduced environmental effects must be
weighed against possible effects on processing the continually leaner sulfide
ore bodies adaptable to beneficiation by froth flotation. Losses of metal
value to tailings or the misplacement of metal values into the beneficiated
ore due to less selective flotation separations also may produce undesirable
environmental and economic effects. Therefore, any displacement of optimized
beneficiatiOfl processes ‘based on the use of sodium cyanide as a depressant
by one using an alternative pyrite depressant, can have a substantial impact
on an important sector of the mining industry.
A further campaign, as Phase II of the Program by Battelle in pursuit
of the overall objective, revealed that a final evaluation of the project
could not be made without considerable additional research and development.
Most, if not all, of the companies interviewed were fully aware that alternate
reagents for cyanide as depressants for iron sulfide minerals had been proposed
long ago. Some had done developmental work on them. None reported favorable
results.
Battelle therefore suggests a new approach, because the cyanide problem
in the copper—lead—zinc industry may not be a true problem. The best and
iv
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shortest way to find out whether cyanide 1$ a true problem is to look at the
data (in the form of self—monitoring reports, compliance monitoring reports,
and the reports of various biologists) in every state where copper, lead,
and zinc plants or mills operate.
After reviewing these data, determine which mills are exceeding their
cyanide discharge limitations, which mills are causing environmental problems,
and/or which mills show no promise. of correcting such conditions.
Give three options to the mills discovered through the data review: (a)
close their circuits and close discharges to waters of the state; (b) apply
end—of—pipe treatment to destroy cyanide in their effluent; or (c) supplant
cyanide as a reagent in their process. If they accede to alternative (c)
above, back them up with whatever financial support that may be available, to
them, to conduct laboratory research and pilot—plant work.
V
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CONTENTS
FOREWOR])
ABSTRACT
INTRODUCTION
CONCLUSIONS
PHASE I ALTERNATIVES FOR SODIUM CYANIDE FOR FLOTATION
TASK 1. LiTERATURE SEARCH
TASK 2. ASSESSMENT OF ALTERNATIVES TO CYANIDE
AS FLOTATION CONTROL REAGENT
TASK 3. LABORATORY STUDIES
CONCLUSIONS
PHASE II
METHOD OF INVESTIGATION
ITEMS OBTAINED ON THE VISITS
SUMMARY OF RESULTS FROM THE SURVEY
DISCUSSION OF COST OF CONVERTING TO AN
ALTERNATIVE REAGENT FOR DEPRESSING PYRITE
CONCLUSIONS
RECOMMENDATIONS
APPENDICES
A. Relevant P e erences Identified by Computer Search arid
Books and Articles Examined in the Literature Search
B. Basic Information Evaluation and Ranking of
Depressants Uncovered in the Literature Search
C. Table C—i. Mills Visited During Study
Table C—2 . Form Used for Discussion with Plant Contact
0. Data Sheets from Mills A through Q and Discussion of
Data Obtained
E. Flowsheets of Typical Milling Operations
p p a a
CONTROL
• . , . . ii
iii
iv
iv
1
2
3
9
18
• . • 2u
20
• . . 21
* . . 22
23
25
26
• . . . A—i
• . . B— I
p C’• I
C—2
0—i
D-3
vi
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TABLES
Number P gc
1 Evaluation and Ranking Criteria for Pyrite Depressants
2 Pyrite Depressant Evaluation and Ranking 5
3 Dry Sieve Analysis of As—Received Ores ii
4 Wet Sieve Analysis of Ball—Milled Ores 12
5 Experimental Conditions for Batch Flotation Experiments
6 Chalcopyrite Ore Results
7 Copper—Lead—Zinc Ore Results 17
8 Zinc Ore Results
vii
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PHASE I
ALTERNATIVES FOR SODIUM CYANIDE FOR FLOTATION CONTROL
The economic recovery of copper, lead, and zinc from the sulfide
ores of these metals in the United States always requires an initial con-
centration step, or steps. The flotation process is almost always a part
of concentrating operations, often the major part. Flotation is a process
for physically separating and collecting valuable minerals from other
minerals that may be present in an ore. The process works like this: An
ore is crushed and ground to such a fineness that its mineral components
are “liberated”——that is, disconnected from each other and so behave
characteristically in subsequent operations. The ground ore, slurried in
water, is treated with various chemicals called “reagents” which havi the
property of attaching themselves to the surfaces of specific minerals in
the mixture. The nature of the reagents is such that the coating they
provide is water repellant and has an affinity for air. Fine air bubbles
are then introduced into the slurry of ore in water. As they rise to the sur-
face they come into contact with the selectively coated particles. These
attach themselves to the air bubbles and are levitated to the surface of the
flotation vessel, much as heavier—than—air objects can be lifted by a balloon.
On the surface of the vessel the air bubbles and their burden of coated min-
erals collect in a “froth” which is made stable, or persistent by the use of
other chemicals called “frothing agents”. This froth is then scraned off the
surface of the vessel or “cell” into troughs and is collected as a “concen--
trate” of the mineral that had been selectively c ated.
This is the basic mechanism of flotation, but it is never that simple
in actual practice where ores may be complex and variable and where such
things as costs, grade, recovery, smelter penalties and marketability are
always uppermost in mill operators’ minds. Fortunately, there are many ways
available, well understood by flotation experts, to modify this basic process
so as to obtain close to optimum results. (1-15)
One such modification is the basis for the work undertaken on this
project. It is the use of cyanide in the copper, lead, and zinc mlfling
industries as a depressant for pyrite in the flotation of copper, lend, and
zinc minerals. Many of the collectors used in the flotation of these minerals
nlso coat iron sulfide particles, with the result that they too float with the
valuable minerals, significantly lowering the grade of concentrates obtained.
The use of cyanide has been found to prevent this co—flotation of pyrite.
1
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Aware of the wide use of cyanide in the base—metal mineral industries as
a pyrite depressant, EPA engaged Battelle to conduct a two—phase program to
determine the feasibility o substituting alternative reagents for cyunide (a
priority pollutant).
Phase I of the program was to consist of limited experimental work to
identify possible substitutes for cyanide as a pyrite depressant.
Phase II, contingent on the outcome of the Phase I work, was designed
originally to determine the practical and economic impact on the Industry of
a changeover from cyanide to alternate reagents indicated as being feasible
by the Phase I work.
The Phase I work indicated that sodium sulfide and sodium sulfite might
possibly be satisfactory substitutes for cyanide. In the Phase II program,
which involved interviewing the officials and supervisors of seventeen copper,
lead, and zinc mills in four states, It was early recognized that it would be
impossible in the scope of this effort to quantify the cost of a changeover
to alternate reagents. This phase culminated in a recommended plan for estab-
lishing such a changeover.
TASK 1. LITERATURE SEARCH
The literature of the period 1968—1978 dealing with pyrite depressants
was surveyed using the computer search of these data bases: Chemical
Abstracts, Smithsonian, Dissertation Abstracts, Engineering Index, and NTIS
(National Technical Information Service) . Key words which were used in the
broadly defined search were the following: flotation, ore treatment, chal—
cocite, chalcopyrite, sphalerite, galena, pyrite, depress .
A total of 38 articles relevant to the topic of pyrite depression wore
identified in the computer search. (A complete listing appears on page A-i,
Appendix A.)
A review of the books and articles (see page A—6, Appendix A) acquired
had the following objectives:
• Identify substances other than sodium cyanide which have
been or may be used as depressants for pyrite.
• Gather information concerning the performance, selectivity,
environmental hazards, and economics of the use of such
• alternatives.
Fourteen candidate depressants were identified. These substances ‘nay
be grouped into classes as follows:
• Netal salts —— silver, chromium, mercury, copper, aluminum,
and iron salts (tested as nitrates in the literature) ——
these are thought to produce a complex of collector molecules
and metal hydroxides on mineral surfaces, thus preventing
collector contact with the mineral (16, 17).
2
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• Reducing agents —— sodium sulfide, sodium thiosulfate, sodium
hypophosphite, sodium oxalate, and sodium sulfite (or other
soluble salts of the same anions) —— these decrease the
oxidation potenLial of the solution and are preferentially
oxidized at the pyrite surfaces (7). Thus they prevent
collector oxidation in the bulk solution or at the solution/
mineral interface. Without the presence of the oxidized
collector, pyrite flotation is inhibited.
• Oxidizing agents —— potassium perrnanganate, sodium dichromate ——
these, on the other hand, act on the pyrite surface to destroy
the hydrophobic character of the surface by forming the metal
hydroxide.
• Miscellaneous —— Kr6D (lignin derivative) —— the mechanism of
pyrite depression is not clear in the case of Kr6D.
Information from the literature on each of the alternative depressants
is summarized in Tables fl—i through B—9 in Appeio ix B. In each case infor-
mation was sought concerning the depressant’s performance on pyrite, selec—
tivity, environmental, considerations, economics, and state of development.
In addition, the theory of depressant action, when known, was summarized.
Tables B—I through B—9 also contain comments considered in the evaluation
and ranking in the fol1owin . task.
TASK 2. ASSESSMENT OF ALTERNATIVES TO
CYANIDE AS FLOTATION CONTROL REAGENT
The information obtained in the literature search was evaluated to deter-
mine three alternative depressants with the best combination of the following
attributes:
• Effective pyrite depression
• Selective depressant action (good desired metal recovery)
• Low environmental pollution potential
• Cost per ton of or processed similar to cyanide
• High state of development as a practical depressant
• Low toxicity.
The approach to the bacic assessment strategy was to score ccc l i candi-
date based on possession of the attributes noted above and to rank the depios-
sants according to the scores thus assigned. A reagent was given a “-1-’ rut n ,
on performance (see Tiible I) if a relatively small reagent concentration pro-
duced a high degree pyrite rejection in flotation tests. A “ —“ performance
3
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TABLE 1. EVALUATION AND RANKING CRITERIA FOR PYRITE DEPRESSANTS
Attribute
Performance rating
+
Performance
High pyrite rejection levels, reasonably
low depressant concentration required
Low to moderate pyrite
rejection levels, high
depressant concentration
required
Selectivity
No interference with subsequent flota—
tion steps, high recovery of nonpyrite
minerals
Interference with subsequent
flotation steps, low recovery
of nonpyrite minerals
Environmental
cons iderat ions
Generally considered nonhazardous
Potentially hazardous
Cost considerationS(’O)
Cost per ton of ore processed similar
to cyanide
High cost per ton of ore
processed
Developmental status
Used commercially in pilot plant or in
extensive laboratory-scale optimization
Subjected to screening tests
only
(a) A value of “0” will be assigned to a particular depressant if insufficient information is
available for assignment of a “-I-” or “—“ value.
(b) A favorable impact on cost would take into consideration not only the cost of the depressant
but also the need and complexity of wastewater treatment if it were used.
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TABLE 2. PYRITE DEPRESSANT EVALUATION AND RANKING
Environmental
Total
Conaiderations
(b)
Deprecsant Performance eiectiv tvth) nd Toxicity(b)
Cost
Consid
erartons
Developmental
Status(b)
Evaluation
Score Rank
Heavy Metals
( as nitrate salts )
Ag + + —l 6
Cr(Ttl) + — — —3 12
Hg(Il) + —3 12
Cut !!) — — — —5 14
Al — — + + — —l 6
Fe(Iil) + + —l 6
Reducing Agents
(a)
:2S2O3 + + + ÷ + (a)
NaH 2 rO 2 -4- 0 0 — —1 6
NaC 2 O + 0 + 0 5
2 2 6 (a)
Na 2 SO 3 + + + + + +5 1
Oxidizing Agents
KMnO 4 + 0 —2 10
Na 2 Cr 2 O 7 + 0 —2 10
Miscellaneous
Kr6D 0 + 0 0 0 +1 4
(a) Selected for screening study.
(b) Each “4-” or “—“ has a value of 1.
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rating was given if a relatively large reagent concentration was needed to
produce a high or low degree of pyrite rejection, if a “+“ or Itfl rating
could not be assigned on the basis of information found in the literature, a
rating was given. The other evaluation criteria were treated In the
same way, according to the criteria descriptions set forth in Table 1.
After a depressant received ratings on all criteria, the individual +, -,
and 0 ratings were added to produce a total evaluation score. When all
alternative depressants had received total scores, ranks from 1 through 1
were assigned based on the total evaluation scores.
All the individual criterion scores, total evaluation scores, and ranks
are summarized in Table 2 for all of the alternative depressants. For
example, sodium sulfite has a total score of “+5”, the sum of five “+“ ratings
for each of the attribute areas. On the other har.d, potassium permanganato
has a score of “—2”, the sum of “—“ ratings for environmental hazard, high
cost per ton of ore processed, and low developmental status; a “0” rating for
insufficient information concerning selectivity; and a “+“ rating for good
pyrite depression performance. The relative ranks of sodium sulfite and
potassium permanganate based on the criteria cited are, as a result, “1” and
“10”. *
Performance and Selectivity of Pyrite Depressants
A number of p ’iite depressants cited in the literature exhibited good
performance in depressing pure pyrite, but there are fewer examples of sub-
stances which selectively depress pyrite. Among the metal nitrates, in tests
using 0.06 lb/ton (0.03 kg/metric ton) potassium ethyl xanthate (KEX) as
collector and 0.20 lb/ton (0.10 kg/metric ton) of terpineol as frother (p11
unspecified), pyrite depression was achieved with additions of 0.4 lb (0.2 kg!
metric ton) AgNO 3 /ton, 0.8 lb (0.4 kg/metric ton) Cr(N0 3 ) 3 /ton, 1.0 lb (0.5 kg!
metric ton) HgNO 3 ) /ton, 4.0 lb (2.9 kg/metric ton) Al(N0 3 ) 3 /ton, or 7.0 lb
(3.5 k /nietric tony Fe(N0 3 ) 3 /ton (18). Thus silver, chromium (III), and mercury
(II) salts exhibit good performance in pyrite depression; however, additions
less than 0.2 lb (0.1 kg/metric ton) Cr(N0 3 ) 3 /ton and 4 lb (2 kg/metric ton)
Hg(N0 3 ) 2 /ton under similar conditions completely depress galena; and less thar,
1 lb (0.5 kg/metric ton) Cr(N0 3 ) 3 /ton completely depresses chaleocite. Silver
is considerably more sensitive than Cr (III) and Hg (II) in that a 5—lb (2.27
kg) AgNO 3 addition depresses only 58 percent of a galena sample (18). In short,
soluble salts are the only metallic salts which combine performance and
selectivity. Their cost, however, is high and will remain so.
The reducing salts sodium sulfide (Na 2 S), sodium thiosulfate (Na 2 S 2 O 3 ),
sodium hypophosphite (NaH 2 PO 2 ), sodium oxalace (Na 2 C 2 0 4 ), and sodium sulfite
(Na’,S0 3 ) are all good pyrite depressants in conformance with the theory that
reduction of solution oxidation potential depresses pyrite by preventing xan-
thate oxidation. At pH 10, 2 x l0’ additions of Na 2 S, Na 2 S 2 0 3 , NaH 2 PO 2 ,
Na 2 C 2 0 4 , and Na 2 SO 3 , respectively, yielded pyrite depressions of 100, 98, )8,
95, and 100 percent (7). Less information Is available concerning the
* The need for more data here is obvious and, onc’ more information is avail-
able, rankings and criteria for ranking are exrected to change.
6
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selectivity of these substances as pyrite depressants. Sodium sulfide has
been shown to have poor selectivity toward pyrite depression in the presence
of galer a, chalcocite, and chalcopyrite (19). No information was found on
selectivity of sodium oxalate and hypophosphite. Sodium thiosulfate exhibits
good pyrite depression selectivity over copper and lead minerals, but poor
selectivity over sphalerite (22). The depression of ZnS by sodium thiosulfate
may not be a disadvantage, since it parallels the behavior of sodium cyanide.
Finally, sodium sulfite is highly selective in depression of pyrite over
depression of chalcopyrite .
Little information on the performooce and no information on the selec-
tivity of potassium permanganate or sodium dichromate is available in the
references reviewed. One source simply stated that these two oxidizing agents
are among the best pyrite depressants (23). Thus, IQ’inO and Na Cr 07 were
given positive ratings on performance and “0” ratings ( nsuffic en informa—
Lion available) on selectivity.
The new patented lignin derivative, Kr6D, is a case where information is
strictly limited, but what is available is cncouraging. The substance is a
mixtu.-e of a soluble polymer, sodium carboxyn ethy1ce1lu1ose, and a soluble
lignosulfonate salt, sodium or calcium lignosulfonate. Kr6D has been shown to
completely depress alena and sphalerite at concentrations as low as 10 ppm
and 5 ppm, respectively, while requiring 100 ppm for chalcopyrite depression
(24, 25). Thus, selectivity against chalcopyrite depression has been demon-
strated, but performance on pyrice is unknown.
Environmental Considerations
There is little or no published information concerning the environmental
aspects of alternatives to cyanide. Thus, it was necessary to evaluate the
alternative reagents without the benefit of data from the literature on
environmental aspects of the problem.
Rather than assigning ‘0” (insufficient information) values to all
candidate depressants in the environmental part of the evaluation process, ii
was decided that most of the reagents could be assigned “hazardous” or
‘nouhazardous” ratings on the basis of common knowledge. Such a grouping,
although not a rigorous comparison of the environmental hazards of the mate—
rials, would be preferable to an assumption that all of the depressants are
equal in this regard.
The heavy metals, silver, chromium, mercury, and copper were given a
(tiazardous) rating on the basis of the commonly known toxicity of the soluble
cations (only soluble metal salts would be useful as flotation roagents) of
the metals, and tile carcinogenic properties of certain chromium compounds in
particular. On the other hand, the metals aluminum and iron were rated “-f
(nonhazardous) on the basis of their easy removal from solution.
7
-------
Of the five reducing agents which were considered, only one was given
a rating: sodium oxalate, due to its toxicity. Sodium sulfide, thie—
sulfate, and sulfite were rated +1. Although all of the reducing agents
would be associated with high chemical oxygen demand (COD), the quantities
which would be released from the flotation process should be much too unnill
to have a significant effect. Sodium sulfide would release toxic H 2 S gas if
exposed to an acidic solution. Since any Na 9 S released with tailings would
be exposed to dissolved heavy metals, residual Na 2 S could be precipitated
as metal sulfides. The degree of hazard associated with the use of sodium
hypophosphite is not commonly known.
Both oxidizing agents, potassium permanganate and sodium dichromate,
were given a rating because they contain the heavy metals manganese and
chromium. Although little information is available concerning the dcsages
of these reagents needed for pyrite depression, it was assumed that hazardous
quantities could be released from a flotation plant, even If only in abnormal
plant operation.
Since Kr6D is a new commercial product, no Judgment of its cnvironInent ii
hazards could be nade. A ?IQTI rating was thus assigned to Kr6D in the envjr n—
mental phase of evaluation, denoting the total lack of published informntj( ,fl
on Kr6D toxicity in the minerals processing literature.
Economic Considerations
The economics of reagent used received no attention in the recent litero—
ture review. As in the case of the environmental evaluation, the ln:k of
specific information in the literature requires that the candidate depressants
be classified as high or low cost per ton of ore processed, on the basis of
common knowledge of the cost of reagents. Rated as low cost per ton of ore
processed are the following: iron and aluminum salts, sodium sulfide, sodium
thiosulfate, sodium oxalate, and sodium sulfite. High cost reagents nrc as
follows: silver, chromium, mercury, and copper salts, sodium hypophospl)jte,
potassium permanganate, and sodium dichromate. Nothing is known about the
cost of lignin derivatives such as Kr6D.
Development Status
According to the literature reviewed, very few of the alternative
depressants have been extensively tested or used commercially. Sodium
sulfide and sodium sulfite both have been used commercially. Sodium thIo—
sulfate has been tested for performance and selectivity more extensively
than the other depressants, although no references to its commercial use
were found in the literature. Thus, these three alternatives received “+“
ratings.
Little is known concerning the development status of Kr6D. The manu-
facturer has tested it on ores containing galena, sphalerite, chalcopyrite,
and molybdenite, and states that Customers have tested It on other ores (27).
The lack of information earns Kr6D a “0” rating in this category.
8
-------
No references to extensive testing or use of any of the other depressants
were found. Thus, all of the remaining alternative reagents received a
rating on developmental status.
Selection of the Most Promising
Alternative Pyrite Depressants
The three reagents with the highest ranking in the evaluation are sodium
sulfide, sodium thiosulfate, and sodium sulfite, with respective evaluation
scores of +3, +5, and +5. Sodium cyanide, evaluated according to the same
criteria, would have a total evaluation score of +3 and a rank of 3. Thus,
tLiCSe three reducing agents are selected as the most promising alternatives
to cyanide as a pyrite depressant. They were the three reagents to be corn—
pared to cyanide in laboratory tests of performance and selectivity on three
different ore types.
Recommended Additional Data
Acquisition and Research
KrÔD ranked fourth in the evaluation (+1, rank = 4). Because the lack of
published information on this reegent is primarily responsible for its poor
showing, new information as i becomes available may well change its standing.
As a natural product, used in low concentrations (5—100 ppm), it may well
prove to be economical.. It has already been demonstrated to be an effective
galena and sphalerite depressant, with selectivit , against chalcopyrite, and
may well be an effective pyrite depressant. Thus, it would be wise, when
more funding becomes available, to attempt to fill the data gaps concerning
Kr6D, especially in regard to its performance on pyrite and its environmental
effects.
None of the other alternatives appear to be worth looking more closely
at individually, as each has overall limitations as a pyrite depressant.
Several, however, may have utility in combination with other more effective
ruager ts. For example, tho use of Kr6D in combination with either sodium
dichromate or SO 2 has improved the grade of a copper concentrate over that
produced by Kr6D alone (25). This and other symbiotic effects of two
or more reagents ought to he studied carefully.
‘I’ASK 3. LABORATORY STUDIES
The three pyrite depressants selected for comparison with sodium cyanide
were sodium sulfide, sodium thiosulfate, and sodium sulfite. A domestic
chalcopyrite ore, a copper—lead—z inc ore, and a zinc ore were used in the
study.
9
-------
The chalcopyrite ore sample was a rod—mill feed with about 4.3 percent
moisture and had the size distribution given in Table 3. The rod—mill feed of
the copper—lead—zinc ore (4.5 percent moisture) was slightly finer. The zinc
ore was significantly finer (see Table 3) and generally dustier than the
other two ores. The zinc ore was considered to be a product from a rod mill
rather than the feed to the mill, although its origin was not specified.
The ores were reduced in size by wet ball milling just before each
flotation test (500 g minus 1/4—inch ore, 750 ml H 2 0, 8025 g steel balls). The
grinding period was determined experimentally in a single experiment with the
target being 65 percent minus 200 mesh. The results given in Table 4 suggc c-
ed that each of the grinding times had to be reduced 5 minutes for the sampLes
to be froth floated.
Sample and Reagent Preparation
Each ore sample was coned and quartered to split out a head sample and
the remainder divided into 20 representative samples, each containing approxi-
mately 500 g ore. Fresh collector solution was prepared just before each
flotation with distilled water at a concentration of 1.25 percent by weight
because the xanthate solution oxidizes easily. In addition, solutions of the
selected depressants were prepared with distilled water at the molar concen-
trations needed for the flotation study.
Experimental Conditions
With each ore sample, a series of froth flotation experiments was carried
out to evaluate the performance of the selected depressants. Additional flo-
tation runs were made without using any depressant and with sodium cyanide to
provide baseline data for comparison. Depressant concentration and the pt-I
were varied at two levels. Remaining variables such as pulp density, rotation
speed, retention time, and air flow rate were held constant.
The fixed conditions for the batch flotation experiments were as follows:
• Collector —— KEX @ 1 ml of 1.25 weight percent solution
• Frother —— Aerofrother 65 @ 3 drops
• Pulp density —— 20 weight percent (i.e., 500 g ore in 2000
ml distilled water)
• Agitator speed —— 1000 rpm
• Retention time —— 8-mm conditioning arid 8—mm floating
• Air flow rate —— natural suction.
10
-------
TABLE 3. DRY SIEVE ANALYSIS OF AS—RECEIVED ORES
Percent y Weight
Mesh Size, Tyler Fraction Cumulative
Chalcopyrite Ore
+1/2” 5.2 5.2
1/2” x 1/4” 22.3 27.5
1/4” x 14 47.4 74.9
14 x 20 5.1 80.0
20 x 28 4.3 84.3
28 x 35 3.6 87.9
35 x 48 3 6 91.5
48 x 65 2.5 94.0
65 x 100 2.2 96.2
—100 3.8 100.0
Copp r—Lead—Zinc Ore
+1/2” 8 4 8 4
1/2” x 1/4” 22 8 31 2
1/4” x 14 37.1 68.3
14 x 20 4.5 72.8
20 x 28 3.6 76.4
28 x 35 3.1 79.4
35 x 48 3.4 82.9
48 x 65 2.7 85.6
65 x 100 3.1 88.7
—100 11.3 100.0
Zinc Ore
+1/2 0 0
1/2” x 1/4” 1 3 1.3
1/4” x 14 43.5 44.8
14 x 20 6.5 51.3
20 x 28 6.0 57.3
28 x 35 6.1 63.4
35 x 48 5.9 69.3
48 x 65 5.5 74.8
65 x 100 4.7 79.5
—100 20.9 100.4
11
-------
TABLE 4. WET SIEVE ANALYSIS OF BALL-MILLED ORES
Percent by Weight
lesh Size, Tyler Fraction Cumulative
Chalcopyrite, 25—mm grind
+65 0.5 0.5
65 x 100 1.0 1.5
100 x 150 3.3 4.8
150 x 200 8.7 13.5
200 x 270 9.4 22.9
270 x 325 7.8 30.7
—325 69.3 100.0
Copper—Lead—Zinc Ore, 25—mm grind
+65 0.8 0.8
65 x 100 0.6 1.4
100 x 150 3.0 4.4
150 x 200 6.8 11.2
200 x 270 7.9 19.1
270 x 325 10.5 29.6
—325 70.4 100.0
Zinc Ore, 20-mm grind
+65 0.25 0.25
65 x 100 1.05 1.30
100 x 150 4.19 5.49
150 x 200 12.01 17.50
200 x 270 9.41 26.90
270 x 325 9.76 36.67
—325 63.34 100.01
12
-------
Except for the zinc ore. sample, 18 batch flotation runs were made at the
experimental conditions shown in Table 5. Results from the first two experi-
ments suggested that only the 12 experiments noted as (d) needed to be carried
out on the zinc ore.
perimenta1 Pcocedure
The experimental procedure for batch flotation experiments was as fol—
lo s, except where otherwise stated:
(1) Place 500 g of the ore sample in the flotation cell and
add 2000 ml of distilled water
(2) Add the prepared detressant solution to obtain the pre-
determined concentration, i.e., l0 - M or i — M
(3) Add 0.5 g of CaO
(4) Agitate the slurry for 5 ruin at a speed of 1000 rpm
without aeration
(5) Measure the pH of the slurry
(6) Add 1 ml of the collector solution (1.25 weight percent
KEX) and agitate 3 ruin without aeration
(7) Add three drops of Aerofroth 65 and turn the air on
(6) Collect froth product for 8 mm
(9) Turn off the agitator and skim off the remaining froth
product
(10) Filter both froth product and tailings separately
(11) Dry the filter cakes overnight in an oven at about 100°C
(12) Weigh the dried cakes and send for analysis.
Chemical Analysis and Performance Evaluation
Both froth product and tailings from each flotation run were analyzed
for their metal contents: i.e., Fe and Cu for the copper ore; Fe and Zn for
tire zinc ore; and Fe, Cu, Ph, and Zn for the copper—lead—zinc ore. The
Lhrec ore head samples were also analyzed for their metal contents.
The flotation results were evaluated In terms of the following parameicrs:
Wt of Product
Total Weight Recovery (ifl) = eu Product + Wt of Tailings x 100
13
-------
TABLE 5. EXPERIMENTAL CONDITIONS FOR BATCH
FLOTATION EXPERIMENTS
Run
No.
Type
Depessnnt —-____
Concentration, M
p11 Adjustment
1 (d)
2 ’
None
None
—-
Neutral (8)
CaO
3 (d)
4 (d)
5 (d)
6
NaCN
NaCN
NaCN
NaCN
10_s
10
iol
10
Neutral or >7(
CaO
Neutral cr
CaO
7 (d)
8 (d)
9
10
ll
12 ’d’
l3 d
14
15
16
17
18
Na 2 S
Na 2 S
Na S
Na 2 S
Na 2 SO 3
Na 2 SO 3
Na 2 SO 3
2 °3
Na 2 S 2 0 3
Na 2 S 2 0 3
Na S C)
Na S O
io
10
103
10
1o
10
3.03
10
10
103
10
10
Neutral
CaO
Neutral
CaO
Neutral
CaO
Neutral
CaO
Neutral
CaO
Neutral
CoO
(a) The pH of the slurry was not adjusted.
(b) The pH was raised by adding 0.5 g of fresh CaO.
(c) With NaCN the pH of the slurry was kept above 7 by adding
NaOH if necessary.
(d) Conditions used in the 12 zinc ore experitnents.
14
-------
( % Metal in Product)(Wt of Product) x
Metal* Recovery =
(Initial Sample Weight)
(kg/metric ton
of ore)
Results
Chalcopyrite Ore (Cu = 0.73; Fe 4.51 percent)——
Eighteen flotations were performed on a freshly ground copper ore (at
least 65 percent minus 200 mesh) using the selected depressants, sodium cyanide,
and no depressants as described in the experimental procedures above. The odd
numbered experiments listed in Table 6 were performed at natural pH while the
even numbered experiments were treated with a fixed amount of lime to raise the
pH.
The results in Table 6 show that under the conditions of these experiments
copper recovery at both natural and high pH was 4.6 and 4.22 kg/tonne, respec-
tively, when NaCN (l0 M) was used as a pyrite depressant. Copper recovery
attained with NaCN was matched or surpassed using Na S (Experiments 9 and 10
at 5.07 and 4.98 kg/tonne, and Na 2 SO 3 (Experiments 1 and 18 at 4.68 and 5.23
kg/tonne). However, the level of pyrite depression, as measured by the Cu to
Fe weight ratio in the float fraction (Cu:Fe of 0.67 to 0.85) obtained by
NaCN only approached that of the Na 2 SO 3 (Experiment 13 where Cu:Fe = 0.68).
Copper—Lead—Zinc Ore (C i = 0.54; Pb = 4.75; Zn 7.98; Fe 4.50 percent) ——
The results from th 18 experiments on a copper—lead—zinc ore employing
the same experimf’ntal conditions used for the copper ore are given iii Table 7.
In Experiments 3A, 4A, 5A, and 6A in which NaCN was used, copper recoveries
were 4.20, 3.66, 3.97, and 3.00 kg/tonne (3.77 avg); lead recoveries were 38.7,
50.5, 37.5, and 34.0 kg/tonne (40.2 avg); and zinc recoveries were 27.5, 34.9,
17.7, and 17.1 kg/tonne (24.3 avg). For copper, equal or greater recoveries
were obtained with each of the pyrite depressants and at each of the concen-
trations studied. The effectiveness of the depressant, as measured by comparing
the Cu:Fe ratios of the froth fractions with those obtained using NaCN (Cu:Fe
of 0.52 to 0.63), was only approached using Na 2 5 (Experiment 8 at 0.47) and
Na 2 SO (approached in Experiments 11 at 0.56 and 14 at 0.48 and exceeded in
Exper ment 13 at 0.62). For lead, recoveries obtained with each of the pyrite
depressants and concentrations equaled or surpassed that attained using NaCN.
The effectiveness of the depressant, as measured by the Pb:Fe weight ratio in
the froth fraction obtained using NaCN (Pb:Fe of 5.80 to 7.16), was approached
using Na S (Experiment 8 at 4.17) and Na 2 SO 3 (Experiments 11 at 5.49, 13 at
4.91, an 14 at 4.64).
In beneficiation of a copper—lead—zinc ore by froth flotation it is often
desirable to suppress the flotation of zinc during the initial separation of
copper and lead. In this study, it is assumed that this is a desired effect
and low values for zinc recovery and Zn:Fe are sought as well as a high recovery
and ratios for copper and lead. With this as an added criterion for the eval-
uation of performance of depressants, Na 2 SO 3 (Experiments 11 at 2.99, 13 at
1.78, and 14 at 2.49) exhibits this characteristic and equals or surpasses the
performance of NaCN (Experiments 3A, 4A, 5A, and 6A with Zn:Fe of 2.79 to 4.96).
* The metal represeflts Fe, Cu, Zn, or Pb.
15
-------
TABLE 6. CHALCOPYRITE ORE RESULTS
Type
Exp. Depressant
Conc., Sampic
N pH Initial
Product
Weig. t, ge Recovery,
ProduLt Tailings Z
Tailings
Analysis
Cu,Z Fe,Z
Cu in
Product ,
Fe in
Product (c)
kg/tor.ne
1 gm
kg/tonne C 1 g ’n
1 (a) None —— 7.8 500.0 44.4 455.7 8.87 0.45 3.04 3.97 1.76 3.52 11.10 4.93 9.86
None —— 11.0 501.1 20.5 480.6 4.09 0.47 2.69 8.44 1.73 3.45 26.50 5.43 10.80
3 NaCN 10 8.0 500.9 32.6 468.3 6.51 0.¾9 3.04 3.94 1.28 2.56 15.10 4.92 9.82
4 NaCN l0 11.0 502.2 24.8 471.5 4.93 0.30 2.55 6.40 1.59 3.17 20.80 5.16 10.30
5 NaCN 10 8.5 504.0 29.9 474.1 5.93 0.30 3.05 7.77 2.32 4.60 9.13 2.73 5.42
6 NaCH 10 10.9 491.3 41.9 649.9 9.62 0.30 3.31 4.39 2.10 4.22 6.55 3.14 6.31
7 NaPS l0 8.5 503.9 40.7 463.2 8.08 0.47 2.95 3.90 1.59 3.16 9.64 3.92 7.78
8 Na 2 S 10 10.8 507.8 54.2 453.6 10.67 0.32 2.31 3.69 2.00 3.94 12.80 6.94 13.70
9 Na S 10 8.0 505.2 69.6 435.6 13.78 0.26 2.57 3.68 2.56 5.07 10.90 7.59 15.00
10 Na 2 S 10 11.0 506.0 38.6 467.4 7 63 0.26 2.46 6.54 2.52 4.98 15.10 5.83 11.50
ii Na 2 SO 3 10’ 8.2 504.0 30.6 473.4 6.07 0.52 3.19 4.96 1.52 3.02 9.81 3.00 5.95
12 Na 2 SO 3 10 10.9 504.8 25.0 479.8 4.95 0.42 2.62 7.86 1.97 3.90 19.10 4.78 9.47
13 Na 2 50 3 1O 8.3 497.4 30.4 467.0 6.10 0.34 2.94 6.81 2.07 4.16 10.00 3.04 6.11
14 Ma 2 SO 3 10 10.9 501.9 44.2 458.7 8.79 0.29 2.38 5.23 2.31 4.59 16.10 7.12 14.20
15 NJ 2 S 2 0 3 10 3.2 501.9 22.9 479.0 4.56 0.40 2.77 7.02 1.61 3.21 13.20 3.02 6.02
16 25203 10 11.0 501.7 41.1 460.6 8.19 0.27 2.58 5.71 2.35 4.68 12.70 5.22 10.40
1/ Na 2 S 2 0 3 IO 8.5 503.5 23.0 480.5 4.57 0.39 2.65 7.71 1.77 3.52 20.00 4.60 9.14
18 Na 2 S 2 O 3 10 11.] 500.8 39.6 461.2 7.91 0.18 2.14 6.62 2.62 5.23 13.80 7.25 14.50
(a) A1 odd—numbered experimenta are natural pH with no pH adjustment.
(b) In all even- numb€ied experimeots the pH was adjusted with 0.Sg CaO; pH beFore depressant addition.
(c) kg/tonne kilogram per metric ton of cre.
-------
TABLE 7. COPPER—LEAD—ZINC ORE RESULTS
t.tII . jj.o!.._ Ca* P, 4 d. t Ft It P?td4 I . PS It Prtd.,ct Za It Py .4. .tI
67 3 Co.3 Ftt 3 7n 3 1 00 k ttt i,i .. z F .- ;— l I . ..
rapt Ct.tp - — _ i .Lf _ ±.71 6 1. 00
tap. fl.prt... t l pH tidal Py.tltct T.lIInt.
—- 7.9 ‘.99.3 59.4 413.7 U.0
S ap - - 10.9 57.8.9 42.0 4)1 134
88C8 lO ..8 4 4.b 4l. 437.6 12.3
—* 91.7.8 70 i0 7 5(79.3 80.4 ‘.29. I 15. 1
50 94.C31 I0 7. 1 500.3 95.3 450.2 30.9
6.4 SaCS IC 0.6 902.6 91.9 455.8 30.2
78 I a .,5 7.8 ‘IIJ.9 (.4.5 446.4 31.6
44 644,4 I0 10.4 503.0 1,6.1 438.9 13.7
40 10 6.4 ‘.93.0 60.6 427.2 13.8
708 64.a,S I0 71.7 499.4 64.0 .55.6 12.8
Ia 88,S4 ( 3 I0 7.9 609 2 51.0 846.0 (0.
118 N,34 13 100 0.8 496. I 90.0 407.3 18.2
#— 378 144,547 4 ’l 5(14.6 40.0 458.4 9.3
74.8 8825471 o 0.7 5(11.9 447.0 44.1.9 12.0
358 88 SJO 7(1 7.7 50.4 64.9 497.6 12.9
168 8 . 5 0 I0 77.0 497.9 80.4 412.5 14.2
178 80970) 7.6 507.8 7,7.7 434.1 71.9
388 t.,5 1 0 1 3 (0.6 ‘.“I.: 63.5 469.9 77.7.
I .) All n J-*, .b . tt..d ..g .. ., ( . t. tt, ..l.a (al.IpHnI ,7. .p0.aj.at.....t.
(63 In .1 1 .,.t-t.. .ttd I.. a.. dl..6. .d . .1II. OS I C .0.
117 kiIt. . 8llna, i..a -Irl. 98406
0.76
3.96
7.74
6.05
3.32
7.83
3.74
0.14
4.78
I II
4.98
1.78
2.77
6.75
3.65
7.58
37.0
78.4
37.2
77 ,
10.50
21.1
0.15
1.29
7.16
5.50
3.42
2.09
4.20
6.72
4.70
8.79
26.6
77.8
3’,6
27.0
14.70
28.7
0.20
7.47
7.38
7.47
2.57
1.87
3.66
5.44
5.33
6.67
37.5
19.7
.8.7
2g.—
13.10
27.9
0.16
4.28
I II
6.95
0.64
2.37
1.97
3.59
7.0-’
11,0
25.7
50.5
22.7
77.80
3
0.74
4.11
7.76
6.46
1.94
3.3?
7.00
1.70
4.34
34..’.
19.0
37.3
16.2
8.93
77.7
0.20
4.04
7.10
7.20
4.18
7.70
3.20
2.81
557
31.3
37.1
34.0
6.8
8.70
17.7
0.15
4.70
1.17
4.27
2.03
7,82
3.40
7.67
5.fl
9.,
17.4
71.0
£1.7
lS.
‘ q
js.
0,17
3.33
0.04
6,68
2.73
3.87
3.78
3.86
7.64
74.8
14.1
11.9
24.8
76.40
17.3
0.34
3.97
0.04
5.66
1.01
1.94
0.00
70.00
7.738
6.46
73.80
27.7
16.6
17.5
76,7.
17.40
23.0
0.74
3.92
0.96
6.39
3.77
.79
1.59
4.55
9.07
26.1
16.7
33.4
9.2
I l. 30
24.6
0.70
3.96
1.30
2.49
1.77
1,92
0.94
5.95
1.17
6.34
32.7
37.4
04.9
77.8
9.47
73.0
0.73
4.80
1.17
6.15
4.4.0
2.02
8.337
7.09
5.60
11.70
70.3
73.9
47.9
24,7
27.00
44.7
0.13
4.58
1.01
5.09
3.37
.98
7.79
6.46
34.8
36.0
03.7
31.6
5.10
77.3
0.72
4.47
0.94
3.90
1.78
7.39
‘.71
7.06
3.92
7.07
10.3
8.1
36.2
16.3
9,79
19.
0.08
4.28
0.77
1.79
2.17
1.91
1.03
9.11
50.6
79.8
39.5
9.6
12.70
23.3
0.72
1.97
0.97
5.37
3.09
2.07
4.37
5.91
4.97
4.00
9.07
78.9
35.7
305
76.9
21.40
4 )4
0.74
3.88
1.1111
5.47
2.91
3.63
1.60
5.93
3.77
7.97
7.48
77.7
27.9
0.4.
77,7
56.7
79.2
13.0
14.70
78.1
-------
Zinc Ore (Zn = 7.09; Fe = 8.15 percent)——
Based on the rc jults of the zlnc fraction from the copper—lead—zinc ore
experiments, only the behavior of sodium sulfite and sodium sulfide as
depressants was examined (only the l0 H concentration of sodium sulfide was
used). The results of 12 experiments using zinc ore are given in Table 8.
The experiment numbering sequence is identical to that used for the previous
ores and that ou llned In the experimental procedure in Table 5. The results
suggest that zinc recovery using NaCN at both natural and high H was about
1.52 kg/tonne at i — M and between 1.1 and 1.2 kg/tonne at 10 M. Both these
values were lower than the 1.59 to 1.68 kg/tonnc zinc recovery obtained when
a d pressant was absent. Zinc recovery attained with NaCN was surpassed using
10 M Na 2 S (Experiments 7B at 1.87 kg and 8B at 1.96 kg/tonne), and Na SO 3
(Experiments 11B at 1.52, 12B at 1.88, and 14B at 1.78 kg/tonne). The eve1
of pyrite depression obtained as measured by the Zn to Fe ratio in the float
fraction was greatest with i0 N Na 2 S (Experiment 8B at Zn:Fe 1.28), and lO
M Na 2 SO (Experiment 14B at Zn:Fe 1.21). These ratios are just slightly
better han those obtained when no depressant was used (Experiment 2B at Zn:Fe
1.22) or when NaCN was used. The fact that sphalerite (ZnS ore) is one of the
most dirficult of the sulfide ores to float is reflected in these exneriments.
Known techniques used to improve the floatability of zinc ores (such as the
addition of soluble copper salts to the system) were not used in these depressant
zc.reening experiments. Since the goal of the experiments was to demonstrate
rejection of pyrite in the float, the conditions used were judged to be a
more severe test of the reagent performance.
CONCLUSIONS
The results from these preliminary screening experiments suggest that
sodium sulfide, Na 2 ., and sodium sulfite, Na 2 SO 3 , could approach the effec-
tiveness of sodium cyanide, NaCN, as a pyrite depressant under the con craints
of this experimental program and the ores studied. The results suggest that
their use should be evaluated as an alternative to the treatment of large
volumes of mining wastewater containing low coricentratlons of cyanide. The
breadth of applicability of such alternative depressants remains unknown and
must be determined. The benefiis of reduced environmental effects must be
weighed against possible effects on processing the continually leaner sulfide
ore bodies adaptable to beneficiation by froth flotation. Losses of metal
value to tailings or the misplacement of metal values into the heneficiateci
ore due to less selective flotation separations also may produce undesirable
environmental and economic effects. Therefore, any displacement of optimized
beneficiation processes based on the use of sodium cyanide as a depressant
by one using an alternative pyrite depressant can have a substantial impact
on an important sector of the mining industry.
18
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TABLE. 8. ZINC ORE RESULTS
Fxp.
Type
Depressant
Conc.
H
pH
Sampl
e Weight,
gm
Product
Recovery,
Nt. 1
Tailings
An 1ysis
Zn in Product
Fe
tonne C 7
In Product
g kg/ton.,e C
InItial
Product
Tailings
Zn.l fe,l
2 gm kg!
IB(a)
None
——
8.5
487.2
18.43
397.4
89.8
8.24 8.71
4.21 0.78
1.59
5.67
i.06
2.16
25 (b)
None
——
10.8
491.7
16.78
409.2
82.5
7.87 9.29
4.93 0.83
1.68
6.07
0.68
1.39
35
NaCN
10
8.5
490.7
16.24
611.0
79.7
7.78 9.31
3.87 0.63
1.28
4.11
0.67
1.36
45
MaCN
10
10.8
693.0
16.06
613.8
79.2
7.94 8.88
6.16 0.67
1.36
3.73
0.60
1.22
58
NaCN
IO
5.6
491.7
16.37
411.2
80.5
8.43 8.98
3.73 0.61
1.26
3.30
0.54
1.10
68
i laCN
1Q
11.0
694.6
14.56
422.6
72.0
7.95 9.05
3.67 0.53
1.09
3.71
0.56
1.09
75
88
118
128
135
145
N a 2 S
Na 2 S O 3
i i . 2S03
Na 2 S O 3
Na 2 S O 3
10
10
10
lo
10
9.0
11.0
8.6
10.8
8.7
10.8
492.1
496.9
491.7
693.4
492.8
491.8
21.44
18.02
17.94
17.92
19.46
17.51
386.6
605.7
403.5
405.0
396.9
606.2
105.5
89.2
88.2
88.6
95.9
87.6
8.17 8.95
7.82 9.83
6.95 8.77
7.50 9.15
7.85 9.33
7.19 9.04
4.31 0.92
5.38 0.97
4.16 0.75
5.19 0.93
4.42 0.86
4.91 0.87
1.87
1.96
1.52
1.88
1.75
1.75
6.11
6.21
3.89
6.37
4.06
4.05
1.31
0.76
0.70
0.78
0.79
0.72
2.66
1.53
1.42
1.59
1.60
1.67
(a) ku odd—numbered experisents are natural p14 wIth no p14 adjustments.
(b) In all even—numbered experiments the pH was adjusted with O.Sg CaO.
(c) kgltonne kilogram per metric ton of ore.
-------
PHASE II
INDUSTRY FEEDBACK
The initial phase of the study was concerned with an evaluation of the
technical effectiveness of reagents which might be used to replace sodium
cyanide for pyrite depression during the flotation of sulfide ores. The
results of that effort identified sodium sulfite and sodium 8ulfide as the
most promising candidate alternative suppressants.
To obtain further information on the feasibility of using these reagents
it seomed logical to determine from the nonferrous metals industry if they
had ever been used or considered for use for this purpose and to determine
the economic impact of ubstitut1ng either of thom for sodium cyanide in
milling circuits to decrease any adverse environmental effects that continued
use of cyanide may have. As the second phase of the study Battelle—Columbus
proposed to visit at least twelve mills which process copper, lead, and zinc
sulfide ores. During these visits relevant information was to be sought on
the effects of the use of alternative pyrite suppressants on the grade of the
concentrates, production rates, recoveries, and reagent usage.
The primary objective of this survey was to determine the economic
aspects of changing from sodium cyanide to one of the alternative reagents.
On an individual basis the cost of (1) the changeover and (2) the long—term
use of the alternative reagent were to be determined if at all possible.
Early in this phase it became clear that definitive data on the practical and
economic feasibility of substituting other reagents for cyanide could not he
obtained by the interview and inspection technique. Accordingly, the approach
had to be modified to obtain enough information for framing a plan that would
eventually permit realization of the original objectives.
The procedure used by Battelle, the findings made, and the conclusions
and recommendations arising from the study are presented in this segment of
the report.
METHOD OF INVESTIGATION
During Phase II of the study members of the Battelle staff visited
eleven companies which operated 17 mills treating copper, copper—lead-zinc,
and zinc sulfide ores in Arizona, Utah, Missouri, and Tennessee. The visits
were carried out during the period of October 29 to November 9, 1979. Table
C—i in Appendix C provides an alphabetical listing of the companies visited,
the state in which the mill is located, and their principal products.
20
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At each site visited, the objectives of the study were explained to the
company official after which discussions were held concerning information
requested to complete the form shown in Table C—2, Appendix C.
The form has space to record the name of the parent company, the desig—
nation and location of the subject mill, the name of the contact, and his
title. It provided for the entry of production data (feed tonnage and grade,
concentrate tonnages and grade, recoveries, cyanide usage, point of addition
of cyanide, purpose of cyanide addition, and the amount of cyanide used per
ton of ore processed). Also covered were the daily volume of the wastewater
discharged to waters of the state, the concentration of cyanide in the dis—
charge, the mode of occurrence of cyanide in the discharge (thiocyanate,
cyanate, ferricyanide, free cyanide, etc.) if known, the cost of the cyanide,
whether the mill had an end—of—pipe cyanide destruction process, whether the
company had an NPDES permit, and, if so, the cyanide limitation and the
company’s ability to comply with the provisions of the permit.
Topics for discussion also Included on the form were
• . The company’s experience, if any, with Na 2 SO 3 or Na 2 S, etc. as
pyrite depressants.
• The company’s opinion of the technical and economic feasibUity of
using alternative depressants.
• The company’s best judgement of how long it would take to change over
to an alternative depressant, assuming that laboratory tests Indicated
the technical feasibility of so doing.
• Any comments on the economic feasibility of changing over.
iTEMS OBTAINED ON THE VISITS
Tables D—I through D—15 in Appendix D present the data obtained during
the visits. Also presented in Appendix D are summaries of the data and the
results of the discussions held with the company representatives. The sec-
tions are grouped by states. Plants are designated alphabetically to
preserve the anonymity requested by many of the contacts. The alphabetical
designation is shown in Table C—I, Appendix C. In some cases two or more
plants are grouped in sections. This is because the same contact spoke for
more than one mill operating In the Immediate area.
Western Mills
Four plants In Southern Arizona and three in Utah were visited. All of
these were predominantly copper producers, but virtually all produced by-
products (Au, Ag, Mo, etc.). The information they furnished is presented
individually in Tables D—1 through D—5 of Appendix D. The Arizona copper
mills did not use cyanide as a depressant for pyrites.
21
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Missouri Mills
Officials from three companies which operate six mills in Missouri were
interviewed. All of these mills were primarily lead and zinc producers, with
copper being a relatively minor by—product. During these visits it was deter—
mined that, contrary to the operation of the Arizona copper mills, virtually
all of the Missouri mills used cyanide as a depressant for pyrites. Their
flotation circuits were much more difficult to operate and sensitive to upsets.
The data sheets for these mills are found in Tables D—6 through D—ll in
Appendix D as are discussions of the individual operations.
Tennessee Mills
Tables D—l2 through D—l5 in Appendix D present the data obtained from
three companies which operate four mills in Tennessee. Three of these mills
were producers of zinc concentrates and the fourth mill produced primarily an
iron oxide product with copper and zinc as coproducts. They are also discussed
individually in Appendix D as Companies N, 0, P, and Q.
It was determined from these visits that when cyanide was used to depress
pyrites in zinc ores it was used at near starvation levels (—0.02 lb oer ton
[ 0.0091 kg/metric toiij of ore processed). Cyanide is not being used in any of
the mills now, but one zinc ore mill which is anticipating closing its mill
circuit plans to return to the use of cyanide to improve the grade (lower
pyrite content). The iron oxide producer uses about 0.1 lb of cyanide per
ton 0.045 kg/metric ton) of ore processed for copper recovery because of the
high pyrite/pyrrhotite content of the ore.
SIJMMARY OF RESULTS FROM THE SURVEY
The results of the survey indicated the following:
(1) None of the six mills visited or contacted by phone in Arizona (all
copper producers) use cyanide or sulfite to depress the flotation of
Iron sulfides, and none discharged to waters of the state or
operated under NPDES permits.
(2) Most of the Arizona plants use cyanide for the separation, by flota-
tion, of molybdenum sulfide from the copper molybdenum concentrates.
This particular use of cyanide was not addressed In h1s study.
(3) One large copper producer in Utah was found to use cyanide to de-
press pyrite flotation, discharged to watern of the state, and was
under the NPDES permit system. Officials of this company stated
that there was no problem with cyanide in the discharges from the
three mills the company operated.
(4) All but one of the six lead—zinc mills visited in Missouri and the
four in Tennessee use cyanide. All but on mill (in Tennessee) use
cyanide in almost “starvation’ amounts. Tiat one, with extremely
high iron sulfide in its feed, used 0.18 lb (0.082 kg/metric ton)
of cyanide per ton of ore processed. These Mi:souri and Tennessee
22
-------
mills all discharged to waters of the state and operated under the
NPDES permit system. Most of the plants practice recycling of mill
waters. According to off: ials, most of the NP’)ES permits did not
limit cyanide, and the measurement for cyanide in effluents was
consistently below detectable levels.
(5) Only two of the i’lants offered any cost information on their present
operation.
(6) None would hazard an estimate of what the total cost differential
might be if a changeover from cyanide to sulfite or sulfide were
made.
(7) On the basis of the information obtained from the company officials
contacted, cyanide in effluents did not i nstitute either an envi-
ronmental or regulatory problem.
Appendix E presents flowsheets of some of the processes used by the
plants visited.
DISCUSSION OF COST OF CONVERTING TO AN
ALTERNATIVE REAGENT FOR DEPRESSING PYRITE
During the survey, an attempt was made to obtain information which would
provide an insight into the economic impact of converting from cyanide to
sulfites or sulfides to depress the flotation of pyrite. It was generally
the opinion of all company officials contacted that the actual conversion to
alternate depressants in the mill itself probably would not require much
plant downtime and probably not much cost differential in reagents. Many
thought that such conversion (after justification by properly designed lab-
oratory tests) could be done in a matter of days or a few weeks at most and
that within this period they would be able to tell whether or not the alter-
natives ‘worked” (i.e. , they consistently yielded high recovery and grade
over a range of ore feeds). Some indicated that it would take a somewhat
longer time to “fine—tune (i.e., maximize recovery and grade and ascertain
that good control was possible) the flotation circuits. One official ex-
pressed the opinion that he would not feel comfortable and fully confident ot
th feasibility of the change until the process modification had operated for
year with consistently satisfactory results.
In Battelle’s opinion, based to a large extent on the response of these
officials and in consideration of the often complex circuits (particularly in
the lead—zinc mills), a reasonably accurate determination of the cost of
changeovers cannot be made at this time with the available data.
The components of such a cost include a number of relevant factors,
having varying degrees of importance. The differences in the costs of
cyanide, sulfite, and sulfide are probably unimportant. The cost of sodium
cyanide at the mills visited ranged from 0.5 to 2.5 cents per ton (0.55 to
2.75 cents per metric ton) of ore treated, based on the usage rate the company
reported and a unit price of about 50 cents per pound ($1.10/kg) for sodium
23
-------
cyanide. One mill, treating an iron—copper—zinc ore to produce iron ore pellets,
copper concentrates, and zinc concentrates, reported a usage rate of 0.18 pound
per ton (0.082 kg/metric ton) of ore feed, equivalent to about 7 cents per ton
(6.35 cents per metric ton). The high usage rate for cyanide at this mill was
necessary owing to the high Iron content of the feed (about 30 percent Fe as
pyrites/pyrrhotite). This mill is not considered to be a typical copper—zinc
flotation mill, its major product being iron ore from which copper and zinc
would have to be separated in any event. In this mill the separation of copper
and zinc by flotation not only removes most of these metals from the iron but
produces valuable by—products or co—products.
Considering the cyanide costs (0.5 to 2.5 cents per ton [ 0.55 to 2.75 cents
per metric ton] of ore being processed) characteristic of most of the mills
visited which used cyanide, it is difficult to see how converting to sulfide or
sulfite could effect any appreciable savings. It is also conjectured that
conversion to sulfide or sulfite at these mills might match or would not add
significantly to reagent costs. This is a conjecture because little is known
at this time about the quantities of sulfide or sulfite which might be required
in a given mill to enable the mill to match the metallurgical results now being
obtained with cyanide. (One company official stated that his company had
tested sulfite as an alternate depressant for pyrite In the laboratory and
concluded that it would add significantly to reagent costs because of the
greater quantity required.) The quantity of these reagents required is a matter
that only can be determined from cdrefully controlled laboratory tests which
simulate mill practice and by confirming tests made in the mill itself.
An additional component of the cost of converting Is cost of the lab-
oratory campaign necessary to evaluate the feasibility of converting. Such a
campaign could entail a large number of tests to fully evaluate and optimize
the conditions required. There is little if any data presently available
that could be used to short—cut development work on a given ore, particularly
a copper—lead—zinc ore. Some of the data on the use of sulfites or sulfides
for pyrite depression in the flotation of copper ore might generally be use-
ful but it would certainly not be adequate to permit optimization of condi-
tions for any given copper ore. However, it is believed that the potential of
sulfide and sulfite as depressants for pyrite should be thoroughly explored
and not dismissed on the basis of results from a few “pilot’ or so—called
‘critical’ tests.
Another component of the cost of converting to sulfides or sulfltes as
depressants for pyrite might be the cost of adding to or modifying mill
equipment to accommodate the process modification. This cost should not be
great, but final judgement must be withheld until the results of laboratory
development work became available. Whatever Increased cost in labor, over-
head, and engineering might be incurred in making and completing the change-
over in reagents also would be a consideration.
What could be, by far, the greatest cost In any change is the potential
reduction in grade and recovery Incurred during the start—up of the modified
process and possibly even after optimum conditions were determined. Many
smelters impose pena].ties on a case—by—case basis for, say, lower grade
concentrates, concentrates with iron and copper percentages above a set
24
-------
value, etc. due to an equivalent loss of production throughput and greater
sulfur oxide capture demand. As an example, one mill reported smelter
penalties for off—grade lead concentrates from a mill processing 700 TPD (635
metric tons/day) of ore as follows:
(1) For every 0.1 percent of copper in excess of 1.0 percent the penalty
could amount to $96,000 per year.
(2) For every 0.1 percent of Iron in excess of 4 percent the penalty
could amount to $264,000 per year.
The penalty is not only im )osed on the mills for the other metals in
concentrate but also for the increased load on the sulfur oxide capture!
utilization facility associated with smelter operations. Due to the presence
of the lighter metal suif Ides or pyrites, for each ton of lead produced,
greater quantities of SO 2 are produced than for higher grade concentrates
thereby limiting output of the smelter to its capacity to capture SO 2 .
CONCLUSIONS
The preliminary experimental work Included in Phase I suggested that
sulfides and sulfites exhibit promise as alternative depressants for pyrite
In the flotation treatment of copper, lead, and zinc ores. Work by other
investigators cited in the first phase also has indicated that sodium sulfite
would be an effective depressant in the flotation of chalcopyrite ores.
The results of this plant survey, however, have shown that the problem
is not a simple one. Most of the copper—producing plants visited in the
Western United States do not use cyanide to depress pyrite flotation. Vir-
tually all of the lead—zinc producing plants in Missouri and Tennessee use
cyanide, hut in almost “starvation’ amounts. Most of these plants are oper-
ated in closed cycle or nearly closed cycle. None admitted to having a
cyanide problem related to their effluents.
None of the officials visited in plants using cyanide and discharging to
waters of the state knew of or had done any work to determine the mode of
occurrence of cyanide in their effluents (i.e., free cyanide, complex cyanides,
cyanate, thiocyanate).
The general impression received from these visits was that cyanide In
plant discharges does not constitute a significant problem or even a dis—
cernable problem inmost cases.
It would be unwise, however, to generalize from this impression. Only
four states were represented out of about 20 in which copper, lead, and zinc
ores are treated for flotation. Only 17 f the estimated 90 to 100 copper—
lead—zinc concentrators in the Uni ted Stat s were covered. Al though the survey
failed to disclose any significant probirin with cyanide in mill discharges,
the possibility that problems do exist in other mills cannot be ruled out.
The following tabulation shows the coverage of the Industry provided by
the study.
25
-------
State
Approximate Number
Cu—Pb—Zn Mills Listed
Directory*
of
in
Number of Mills
Visited or Contacted
In This Survey
Arizona
21
6
California
1
0
Colorado
9
0
Idaho
7
0
Illinois
5
0
Kentucky
2
0
Maine
1
0
Michigan
1
0
Missouri
7
6
Montana
5
0
Nevada
4
0
New Jersey
1
0
New Mexico
ii
0
New York
1
0
Oklahoma
1
0
Tennessee
6
6
Utah
4
3
Virginia
1
0
Washington
1
0
Wisconsin
1
0
Puerto Rico
1
0
TOTAL
91
21
* 1973—74 E/MJ International Director of Mining and Mineral Processing
Operations, published by Engineering and Mining Journal, McGraw—Hill,
New York, NY, 1974.
RECOMMENDATIONS
It is recommended that the study be continued but that a different
approach he adopted——one that would move directly to an objective of elim-
inating cyanide where this is necessary. The specific steps which should be
taken are:
(1) Query all state or federal regulatory environmental control
agencies in states where base—metal milling is practiced, to
determine
(a) Which mills operate under NPDES permits;
26
-------
(b) Which mills are obliged to meet cyanide limitations in
their permits?;
(c) If a mill uses cyanide, but if its permit does not limit
cyanide, why cyanide is not listed?;
(d) Which mills with cyanide limitations in their permits
have violated these limitations within the past 12 months?;
(e) Of the above, what is the current status and prognosis
for future compliance with respect to compliance with
cyanide limitations?;
(f) On what terms does the regulatory agency limit cyanide
in these permits (free cyanide, total cyanide, cyanide
amenable to chlorination)?;
(g) 1as the regulatory agency itself done any work to determine
the mode of occurrence of the cyanide radical in the effluents
from the mills under its jurisdiction?;
(h) } as the mill conducted research studies aimed at substituting
other reagents for cyanide?;
(1) Are reports available on these studies?;
(j) Has the regulatory ac ency encouraged any mill with a
cyanide problem to seek means to eliminate any cyanide
discharge by closing its mill circuit or by installing
an end—of—pipe cyanide destruction process?;
(k) Are reports available on any work covered in (j) above?;
(1) What is the regulatory agency’s assessment of the severity
of the cyanide problem caused by base—metal mills under
its jurisdiction?
The information requested in Item (1) above would simplify and shorten
any program aimed at eliminating cyanide as a mill reagent. It would simplify
the programs to define specifically what must be done, and where the trouble
3pots are.
(2) The information obtained from the regulatory agencies should
be assembled and carefully studied. Should the conclusion he
reached that there is no problt mi with residual cyanide in the
effluents from base—metal mills, the project should be abandoned.
However, incidents are found at various operations throughout
the country where cyanide in effluents has affected the
environment.
These cases should be further pursued in this manner:
(3) Mills with a history of cyanide violations of their NPDES
permits and which show no promise of being able to circumvent
27
-------
their problems, should be approached first. The approach should
be deliberate, formal, and ad hoc In nature. The company should
be notified that it is expected to seek ways and means to eliminate
cyanide from its discharge. It must be recognized that there nrv
several ways to eliminate such discharges. The first is by cbs ! ti ’,
the mill circuit and thus eliminating any cyanide discharge. In
regions of the country with abundant rainfall, this could be diffi-
cult, though not Impossible. A second approach would be to install
an end—of—pipe cyanide destruction process. A third option would
be to investigate the technical and economic feasibility of suhsti—
tuting sulfides or sulfites for cyanide as depressants for pyrites
in the flotation of copper ores and for zinc sulfide and pyrites in
the flotation of lead ores. The companies involved should investi-
gate the technical and economic feasibility of these three approaches
and should submit reports substantiating their findings. It may be
objected that research of the kind required to evaluate the feasi-
bility of using alternative reagents to cyanide ought to be done by
outside organizations. This objection is not valid for several
reasons. An outside organization would not have sufficient expertise
io the company’s operation——which is often an art rather than a
science. The milling company would be able to test freshly mined
ground ore. Any outside organization would be testing ore which is
oxidized and not representative of the freshly mined ore being
treated. In any event, whatever the “outside” organization found
would certainly be contested by the company and would be subject to
confirmation by the company’s own tests. No “outside” organization
knows nearly as much about a company’s practices, the ore’s varia-
bility, or the on—site problems, as the company’s metallurgists.
The time interval between mining of the ore and the subjection of
it to treatment can be critical. Whatever the “outside” organization
found, it Is sure the company would want to confirm the findings.
Whatever work is done on the feasibility of using new reagents must
he done by the company. The company would, of course, have to
submit a report on Its research, which would have to be reviewed
and evaluated by “outside” organizations.
(4) If the results of the studies made by industry, as judged by U.S.
EPA or its contractors, indicate that the process can be translated
to mill—scale, negotiations should be Initiated with the company
to make such a rr ’.nsition to demonstrate the procedure.
28
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APPENDIX A
RELEVANT REFERENCES IDENTIFIED BY COMPUTER SEARCH
and
BOOKS AND ARTICLES EXANINED IN THE LITERATURE SEARCH
-------
APPENDIX A
RELEVANT REFERENCES IDENTIFIED BY COMPUTER SEARCH
Chemical Abstracts Searuh (1970—1978 )
Ca 78: 102457s Magnetic Treatment of Reagents in the Flotation of
Polyxnetallic Ores. Agafonova, C. S., Marasanova, L. V.,
Mart’yanov, Yu A., Chernov.. Yu K. (USSR). Sb. Tr.,
Nauch.—I dled. Proekt. Inst Obogashch. Rud Tsvet.
Met. 1971, No. 2, 145—51.
CA 80: 5898k Comparative Testing of Cyanide Free Methods f or the
Select 4 .ve Flotation of Nonferrous Metal Ores.
Bakinov, K. C., Logniov, C. N. (USSR). Tvvet. Metal
1973, (6), 75—7 (Russ.).
CA 74: 44444e Use of Acid Salts During the Selective Flotation of Ores
from the III [ Tretii3 International Deposit, Bocharov,
V. A., Filimoriov, V. N., Yankina, V. I., Sapozhnikov, V. P.,
Lagutin, P. I., Postovalov, I. P., Charnaya, I. P., Epel’man,
L.L. (USSR). Tsvet. Metal. 1970, 43(11), 81—3.
CA 79: l52219x Use of the Electrochemical Properties of Sulfide Minerals
During the Preparation of Ores for Flotation. Bocharov, V. A.,
Sapozhnikov, V. P., Pospelov, N. D. (USSR). Tsvet. Metal.
1973, (7), 67—90.
CA 84: 93247h Ore Concentration by Froth Floatation Using Polymer and
Lignosulfonate Depressants. Burniston, T. (Imperial Chemical
Industries, Ltd) S. African 74 05, .433 P03d, July 29, 1975.
CA 73: 278011 Use of Sodium Thiosulfate to Depress Pyrite. Dvorak, A.,
Cibulka, .1. (Czech.). Erzmrtall 1970, 23(3), 123—8 (Car).
CA 78: 60808q Inhibiting Action oi Flotation Depressors During the
Oxidation of Sulfides. Filimonov, V. N., Bocharov, V. A.,
Sudnitsyna, V. F. (USSR). Tr. Nauch—Issled. i’roekt. Inst.
Obogashch. Mekh. Ohrab. Polcz. Isokp. “Uralrnekhanobr”
1970 No. 17, 203—9.
A-i
-------
CA 78; 60733in Separation of Copper—Lead Concentrates using Sodium Hydro—
sulfite. Gleinbotskii, 0. V., Klimenko, N. C., Ivanovskaya,
V. P. (USSR). Tr. Tseni. Nuach—Issled. Cornorazved. Inst.
Tsvet., Redk. Blagorod. Natal. 1972, No. 102, 62—8 (Russ).
from Ref. Zh., Khim. 1972.
CA 80: 39494r Flotational Separation of Copper—Lead Concentrates with
Sodium Hydrosulfite. Clembotskii, 0. V. (USSR). Obogashch.
Bednykh Rud 1973, 146—53.
CA 83: 101072u Colloidal Precipitates as Activators and Depressants in
Flotation. Healy, T. W. (Univ. Melbourne, Parkville, Aust.)
Pap. West. Aust. Conf., Australas. Inst. Mm. Metall.
1973, 477—84.
CA 75: 8706d Testing a New Depressor for Sphalerite and Pyrite During
the Separation of the Bulk Concentrate. Konev, V. A.,
Kurilkov, B. R., Eropkin, Yu. I., Brandt, A. 0. (USSR).
Obogashch Rud 1970, 15(5), ‘—6.
CA 7 23238n Mechanism of the Depressing Action of Complexes, Komev,
V. A. (USSR). Obogashch. Rud 1971, 16(5), 23—8.
CA 77: 104189z Replacement of Zinc Sulfate and Part of the Cyanide by
Zincate During the Concentration of Belousovka Daposit
Ores. Konev, V. A., Ageeva, T. F., Egorov, K. C., Chekanov,
N. S., (Leningr. Corn. Inst., Leningrad (USSR). Izv.
Vyssh. Ucheb. Zaved. Tsvet. Met. 1972, 15(2), 7—11.
CA 75: 79273w Use of Sulfite Compounds in Flotation of Complex Ores.
Kosherbaev, K. T., Sokolov, N. A. (USSR). Fi —Khim.
Kompicks. Percrab. Rud Sredn. Azii, 1970, 131—4.
CA 86: 74 7 lp Study of the Physicochemical Characteristics of the Sodium
Sulfite—Iron(II) Sulfate—Water System in Relation to its
Depressing Effect in the Flotation of Suif ides. Kosherbaev,
K. T. (USSR). Metall. Metalloved. 1975, 2, 114—18 (Russ.).
CA 79: 33861r Technological Effects of the Use of Some Alkaline DesorbentS,
Collectors, and Depressors of Sulfide Minerals (except
molybdenite) in the Case of a Copper—Molybdenum Concen-
trate from Majdanpek. Maksimovic, M. (Belgrade Yugoslavia)
Technika (Belgrade) 1972, 27(6), 1096—102.
CA 8 : 4764lj Use of a New Modifier Kr 6 D in Different Sulfide Flotation.
Manser, R. M., Andrews, P.R.A., (Warren Spring Lab.,
Stevenag2, Eng.) mt. J. Miner. Process 15, 2(3), 207—18.
A- 2
-------
CA 87: 2 O 4648 y Mechanism of the Reaction Between Mineral and Flotation
Reagents. Mukai, S. (Kyoto Univ., Kyoto, Japan). Taehan
Kwangsan Hakhoe Chi 1977, 14(2), 97—105.
CA 78: 140016w Use of Sodium Hydrosulfite to Depress Sphalerite During
the Selective Flotation of Lead—Zinc Ores from some Caucasian
Deposits. Nekrasov, B. D., Shul’gina, L. K., Terekhova,
V. B. (USSR). Mater. Nauch—Tekh. Konf. Ser—Kavkaz Gornomet
Inst. 1968 (Pub. 1970), 53-4.
CA 77: 142683p Application of an Electrochemically Mod ,fied Sodium Sulfide
Solution at an Enrichment Plant. Sagradian, A. L., Shafeev,
R. Sh., Abratnyan, S. A.,Stogova, G. B., Isaakyan, R. I.,
Rabinovich, M. P., Shmelev, V. K., Pogosyan, K. A.,
Tolmsdova, C. A., et al. (USSR). Prom. Arm. 1972 (6), 65—6.
CA 78: 100805v Cyanide—Free System for Complex Ore Flotation. Savari, E. A.,
Klimenko, N. G., Shapiro, A. P., Koroleva, E. I., Filinova,
V. V. (USSR). Tr., Tsent. Nauch—Issled. Cornorazved Inst.
1972 No. 102, 51—8.
CA 78: 32672x Oxidation—Reduction In a Pulp During Separation of Lead—
Copper Concentrates by Soluble Manganese Compounds.
Shafeev, R. Sh., Tevonyan, M. S. (USSR). Tr. Kavkaz Inst.
Miner. Syr’ya 1971, No. 9, 337—40.
CA 78: 99812m Composition of a New Depressor, a Collagen—Chromic Salt
Reagent. Skvirskii, L. Ya., Panteleeva, N. N. (USSR),
Tr. Vses. Nauch—Issled. Proekt. Inst. Calurgii 1972, No. 57,
124—33.
CA 79: 33872v Industrial Testing of New Reagent Conditions for the Selective
Flotation of Sulfide Complex Metal Ores. Tyurnikova, V. I.,
Nasekin, V. A., Chernykh, S. I., Bogomolov, V.. N., Linev,
B. I. (USSR). Tr. Inst. Obogashch. Tverd. Goryuch. Iskap.
1972, 1(2), 136—41.
CA 79: 69005d Reaction of Depressants and Activator on Pyrite. Yamamoto,
T., Tsubaki, S. (Japan). Tohoku Daigaku Senko Seiren
Kenkyusho Iho 1972, 28(2), 170—9.
CA 79: 690062 Reaction of Ethylxanthate Ion and Depressants on Pyrite.
Yamatnoto, T., Tsuhaki, S. (Japan). Tohuku Daigaku Senko
Seiren KenkyushO Iho. 1972, 28(2), 180—90.
A- 3
-------
NTIS Search
Baker, A. F. and Miller, K. J., “Hydrolyzed Metal Ions as Pyrite Depressants
in Coal Flotation: A Laboratory Study”, US Bureau of Mines, RI—75l8, May,
1971, 26 p.
Utah Univ., Salt Lake City, Dept. of Mineral Engineering, “Pyrite Depression
by Reduction of Solution Oxidation Potential”, US EPA, December, 1970, 63 p.
PB 200—257.
Engineering Index Search (1968—1978 )
Baimakhunov, M. T., Nechaeva, K. Ya., and Petrova, L. A., “Rational Scheme
for Concentrating Chalcopyrite Barite—Containing Ore of the Naykain Deposit”,
Tsvet. Net. 11, November, 1975, p 75—77 (In Russian).
Manser, R. M., and Andrews, P.R.A., “Use of a New Modifier, Kr6D, In Dif-
ferential Sulphide Flotation”, mt. 3. Miner. Process Vol. 2 (3) p 207—218
October, 1975.
Abramov, A. A., Soloznenkin, P. M., Kulyashev, Yu. C. and Statsura, P. F.,
“Investigations of the Action of Reagents and Optimization of their Concen-
tration in the Flotation Pulp”, Inst. Miner Process Congr., 10th, Proc.,
London, England, April 2—6, 1973, p 633—652. Published by Inst. of Mm.
and Metall, London, England, 1974.
Kubota, T., Yoshida, M., Hashirnoto, S. and Shimolizaka, J., “Fundamental
Study on the Effect of Pulp Temperature in Copper—Lead Bulk Differential
Flotation”, J. Mi Metall. Inst. Japan Vol. 90 n 1040, p 641—644, October,
1974.
Takeuchi, N, and Hatanka, K., “Study on the Role of Oxidation Reduction
Potential in Differential Flotation by Sulfurous Acid of Pb, Zn Ore”,
J. Mining Metal Inst. Japan Vol. 89 n 1026, p 533—538, August, 1973.
Woods, R., “Electrochemistry of Suiphide Flotation”, Australas. Inst. Mm.
Metal Proc. n 241, p 53—61, March, 1972.
Klymowsky, I. B., and Salman, T., “Role of Oxygen in Zanthate Flotation of
Calena, Pyrite and Chalcopyrite”, Can. Mining Met. Bull. Vol. 63, n 698,
p 683—8, June, 1970.
Baker, A. F., and Miller, K. J., “Hydrolyzed Metal Ions as Pyrite Depres-
sants in Coal Flotation: A Laboratory Study”, US Bureau of Mines, Rep.
Invest. 7518, 21 p., May, 1971.
A-4
-------
Dvorak, A., and Cibulka, J. , “Application of Sodiutn Thiosulfate as Depres-
sant of Pyrite”, Erzinetall Vol. 23 n 3 p 134—8, March, 1970.
Kubota, T., Yoghida, M., and Hashimoto, S., “Effect of Pulp Heating on
Floatability of Galena and a Practical Application to Cu—Pb Separation”,
J. Mining Met. Inst. Japan Vol. 85 n 981, p 31—4, January, 1970.
A—5
-------
BOOKS AND ARTICLES EXAMINED
IN THE LITERATURE SEARCH
(1) Klymovski, I. B. and Salman, T., “The Role of Oxygen in Xanthate
Flotation of Calena, Pyrite, and Chalcopyrite”, Canadian Institution
of Mining and Metallurgy Bulletin June, 1970, pp 683—688.
(2) Meligren, Olav, “Heat of Adsorption and Surface Reactions of
Potassium Ethyl Xanthate on Galena”, SHE Transactions , March, 1966,
pp 46—60.
(3) Caudin, A. M., et al, “Adsorption of Ethyl Xanthate on Pyrite”, SHE
Transactions , January, 1956, pp 65—70.
(4) Majumdar, K. K., “Depression of Pyrite by Cyanide Ions”, The Mining
Magazine , September, 1957, Pp 137—139.
(5) Majumdar, K. K., “On the Mechanism of Depression of Pyrite”, 3.
Scientific Industrial Research , 13B, P 586 (1954).
(6) Majumdar, K. K., “On the Role of Alkali Cyanides in the Depression of
Pyrite”, J. Scientific Industrial Research , jiB, pp 344—346 (1952).
(7) University of Utah, “Pyrite Depression by Reduction of Solution
Oxidation Potential”, Water Pollution Control Research Series No.
12010 DIM, U.S. Environmental Protection Agency, December, 1970.
(8) Janetski, N. D., et al, “An Electrochemical Investigation of Pyrite
Flotation and Depression”, International Journal of Mineral Processing ,
4, pp 227—239 (1977).
(9) Poling, C. W. and Leja, 3., “Infrared Study of Xanthate Adsorption
on Vacuum Deposited Films of Lead Sulfide and Metallic Copper Under
Conditions of Controlled Oxidation”, Journal of Physical Chemistry ,
67, pp 2121—2126 (October, 1963).
(10) Majima, H. and Takeda, H., “Electrocheznical Studies of the Xanthate—
Dixanthogen System on Pyrite”, SHE Transactions, 241, December, 1968,
pp 431—436.
A-6
-------
(11) Fuerstenau, l f. C., et al, “The Role of Dixanthogen in Xanthate
Flotation of Pyrite”, SME Transactions , June, 1968, pp 148—156.
(12) Winter, C. and Woods, R., “The Relation of Collector Redox Potential
to Flotation Efficiency: Monothiocarbonates”, Separation Science ,
8 (2), pp 261—267 (1973).
(13) Allison, S. A., et al, “A Determination of the Products of Reaction
Between Various Sulfide Minerals and Aqueous Xanthate Solution and a
Correlation of the Products with Electrode Rest Potentials”,
Metallurgical Transactions , 3, October, 1973, pp 2613—2618.
(14) Woods, R .,, “The Oxidation of Ethyl Xanthate on Platinum, Cold, Copper,
and Galena Electrodes in Ralation to the Mechanism of Mineral Flotation”,
Journal of Physical Chemistry , 75 (3), pp 354—362 (1971).
(15) Elgillani, D. A. and Fuerstenau, M. C., “Mechanisms Involved in
Cyanide Depression of Pyrite”, SME Transactions , 241, December, 1968,
pp 437—445.
(16) Steininger, J., “The Depression of Sphalerite and Pyrite by Basic
Complexes of Copper and Sulfhydryl Flotation Collectors”, SME Trans-
actions , March, 1968, pp 34—42.
(17) Baker, A. F. and Miller, K. 3., “Hydrolyzed Metal Ions as Pyrite
Depressants in COal Flotation: A Laboratory Study”, U.S. Bureau of
Mines, Report of Investigation 75l8,.pp 21 (1971).
(18) Work, I. W,, Principles of Flotation , Australian Institution of Mining
and Metallurgy, pp 212—217 (1938).
(19) Fuerstenau, M. C., Flotation , AIME, 479 (1976).
(20) Hoffman, H. A., “Converting Gravity—Flotation Plant to All—Flotation”,
SME Transactions , June, 1962, pp 208—218.
(21) Gaudin, A. M., Flotation , McGraw—Hill, pp 288—295 (1957).
(22) Dvorak, A. and Cibulka, J., “On the Use of Sodium Thiosulfate to
Depress Pyrite”, Erzmetall , 23 (3), pp 123—128 German (1970).
(23) Ball, B. and Rickard, R. S., “The Chemistry of Pyrite Flotation and
Depression”, in Fuerstenau, M. C., Flotatiofl , 1, AIME pp 458—484 (1976).
(24) Manser, R. H. and Andrews, P. R. A., “The Use of a New Modifier, Kr6D ,
in Differential Suiphide Flotation”, International Journal of Mineral
Processing , 2, pp 207—218 (1975).
(25) William Aitken & Sons, Ltd., “Kr6D: A New Flotation Depressant”,
advertising brochure, Hesketh Honse, 43—45 Portman Square, London
W1HOJP, England (1976).
A- 7
-------
(26) Caidwell, A. B., “A Technical Buyer’s Guide to Mineral Processing
Reagents”, Enginec r ng and Mining Journal , pp 194 (June, 1968).
(27) Personal counication with William Aitken Li Sons, Ltd., Eay 24, 1978.
A- 8
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APPENDIX B
BASIC INFORMATION EVALUATION AND RANKING OF
DEPRESSANTS UNCOVERED IN THE LITERATURE SEARCH
-------
TABLE B-i. DEPRESSANT: HEAVY METAL SALTS
Basic Information: Performance, Cost,
Environmental Hazards, Operating Conditions Evaluation
Depression of pyrite : AgNO 3 , Hg(N0 3 ) 2 , Cu(N0 3 ) 2 , Pet formance : Ag, Cr, and Hg pyrite
A1(N0 3 ) , and Fe(N0 3 ) ; all give good pyrite depression rated as good; Cu, Al, and
depress on (in descenaing order of effectiveness) Fe as poor.
at additions of <7 lb/ton ore. Collector; 0.06
lb/ton KEX;(a ) frother: 0.2 lb/ton terpineol (18);
(—200 mesh)
Depression of other sulfide minerals : CR(III) gives Selectivity : Ag selectivity rated as
good chalcocite depression <0.4 lb/ton. Some metal good; Cr, Hg, Cu, Al, and Fe as poor.
nitrates, except Ag, give good depression of PbS @
additions <5 lbfton (18). Result: not selective
for pyrite depression.
Theoretical justification for use : depression may
occur through formation of basic metal sulfhydryl
collector complexes on mineral surfaces (16).
Environmental hazards : heavy metals would be Environmental considerations: Ag, Cr,
released in wastewater and tailings disposed of in Hg, and Cu rated potentially hazardous;
dumps, ponds, etc. Al and Fe rated as less potentially
hazardous. Heavy metals in solution
are generally considered to be injurious
to heálth,and ecological systems above
certain concentrations.
(Continued)
-------
TABLE B-i. (Continued)
Basic Information:
Environmental Hazards,
Performance, Cost,
Operating Conditions
Evaluation
Cost information: — —
Cost considerations: Ag,
salts rated as high cost;
Cr,
Al
Hg, and
and Fe as
Cu
low cost.
.
Development status: None of the metal
salts have been subjected to extensive
testing as pyrite depressants.
(a) KEX — potassium ethyl xanthate.
(b) See section on Environmental Considerations.
-------
Table B-2. DEPRESSANT: SODIUM SULFIDE (Na 2 S)
Basic Information: Performance, Cost,
Environmental Hazards, Operating Conditions Evaluation
Depression of pyrite : M Na 2 S gives excellent Performance : Pyrite depression rated as
depression @ pH 5—6, complete depression @ pH ‘ 10, good.
with 1 x(a) collector (7). Reference (19) gives curve
of Na 2 S concentration versus pH for prevention of
contact, using 25 mg/i KEX. One plant gets good
results in combination with NaCN, using 0.05 lb/ton
ore of Na 2 S and 0.013 to 0.015 lb/ton ore of MaCN (20).
Depression of other sulfide minerals : Cnrves given in Selectivity : Poor
Reference (19) for PbS, CuFeS 2 , FeS , and CuS Indicate
that pyrite is harder to depress wI h Na 9 S than any of
the minerals except CuS. Thus, selectiv!ty should be
poor except over CuS.
Theoretical justification for use : References (21) and
(18) note thatRS is the actual depressant when Na,S
is added, since the 11S concentration is constant along
the contact curves. References (7) and (8) claim that
s 2 is oxidized preferentially to KEX, preventing
dixanthogen formation and pyrite flotation.
Environmental hazards : If pH goes toward acid side, Environmental considerations : Potentially
H 2 S could be released to the atmosphere, but this nonhazardous unless acidified.
condition is not likely to be encountered in a froth
flotation environment.
(Continued)
-------
TABLE B-2. (Continued)
Basic Information:
Environmental Hazards,
Performance, Cost,
Operating Conditions
Evaluation
Cost information:
Cost considerations: Low cost per
ore processed.
Development status: Rated as high
commercial use as depressant.
ton
due
of
to
(a) KEX potassium ethyl xanthate.
-------
Table B-3. DEPRESSANT: SODIUM ThIOSULFATE (Na 2 S 2 O 3 )
Basic Information: Performance, Cost,
Environmental Hazards, Operating Conditions Evaluation
Depression of pyrite : Reference (7): Good pyrite Performance : Good.
depçe sion (>50%) @ pH 6. Reference (22): Using
KEX ’ collector, n—amyl alcohol frother, pH — 9.2,
200g KCN/ton, 600g ZnSO 4 /ton, 800g NaOH/ton; ore
assay: 88.3% <200 mesh, 0.62% Pb, 2.7% Zn, 3.31%
FeS sulfur; with 700gIton-Na 2 S 03 depressant, 88%
of eS 2 rejected to tails; w/o a 2 S 2 0 3 , 10.5% FeS 2
rejected to tails.
t i D pression of other sulfide minerals : Same ore as Selectivity : Good.
u above, with Na S 03: 5.3% of Cu, 16.2% of Pb, 27.6%
of Zn rej. to ails; yb Na 2 S 0 3 : 5.8% of Cu, 14.92
of Pb, 6.6% of Zn rej. to tails.
Theoretical justification for use : Reference (7)
claims that Na 2 S 2 O 3 reduces solution—oxidation pot.,
thus preventing xanthate oxidation to dixanthate.
Environmental hazards : —— Environmental considerations : Non—
hazardous.
Cost information : — Cost considerations : Low cost per ton
of ore processed.
Developmental status : Insufficient infor-
mation.
(a) KEX = potassium ethyl xanthate.
-------
TABLE B-4. DEPRESSANT: SODIUM RYPOPHOSPHITE (NaR 2 PO 2 •11 2 0)
Basic Information: Performance, Cost,
Environmental Hazards, Operating Conditions Evaluation
Dep;ession of pyrite : lO M solution used with Performance: Good.
collector (2 x iO N) gives 60% depression
@ pH 5.5, 90% @ pH -8 (7).
Depression of other sulfide minerals: Selectivity : Insufficient information.
Theoretical justification for use: Reduces solution
oxidation potential, preventing oxidation of xanthate
(7).
Environmental hazards : —— Envirormientalconsideratlong : Insuffi—
cient information.
Cost information : —— Cost considerations : Probably high cost
per ton of ore processed.
Developmental status : Not developed
beyond screening test stage.
(a) KEX — potassium ethyl zanthate.
-------
TABLE B—5. DEPRESSANT: SODIUM OXALATE (Na 2 C 2 O 4 )
Depression of yrite : M solution used with
2 x i0 M Iu X a) collector gives 60% depression
@ pH -7.5, 90% @ pH -9 (7).
Depression of other sulfide minerals:
Theoretical lustification for use : Reduces solution
oxidation potential, stopping xanthate oxidation (18).
Environmental hazards: —
Cost information :
Basic Information:
Environmental Hazards,
Performance, Cost,
Operating Conditions Evaluation
Performance: Good.
Selectivity : Insufficient information,
Environmental considerations: Hazardous.
Cost considerations : Low cost per ton of
ore processed.
Developmental status : Not developed beyond
screening test stage.
(a) REX = potassIum ethyl xanthate.
-------
TABLE B—6. DEPRESSANT: SODIUM SULFITE (Na 2 SO 3 )
Basic Information: Performance, Cost,
Environmental Hazards, Operating Conditions Evaluation
Depression of pyrite : Na S 03 gives 80% Performance : Good.
depression @ pH -6, with 2 x l0 M KEX(a)
collector, particle size 65 x 100 mesh. Not as
good for —200 mesh particles (7)’.
Depression of other sulfide minerals : With same Selectivity : Good.
i eagent concentrations, doesn’t depress PbS until
pH > 11. Has been used for ZaS depression in
Pb—Zn ores (21).
c o
Theoretical justification for use : Reduces solution
idation potential, preventing oxidation of
xanthate (7).
Environmental hazards : —— Environmental considerations : Non—
hazardous.
Cost information : —— Cost considerations : Low cost per ton
of ore processed.
Development tatus : High; used coer—
I 7 lly in some cases .
(a) KEX — potassium ethyl xanthate.
-------
TABLE B—7. DEPRESSANT: POTASSIUN PERMANGANATE (KMnO 4 )
Basic Information: Performance, Cost,
Environmental Hazards, Operating Conditions Evaluation
Depression of pyrite : Reference (23) says dichromate Performance : Good.
and perinanganate are “two of the most effective
depressants” for pyrite; gives no theoretical justi-
fication. Reference (18) gives plot of pyrite
recovery (%) versus added salt (lb/ton). Addition of
0.4 lb KNnO per ton pyrite gives complete depression
using 0.05 tb/ton xanthate and 0.20 lb/ton terpineol
frother. 100 x 200 mesh particles, pH unknown.
Depression of other sulfide minerals: Selectivity : Insufficient information.
Theoretical justification for use:
Environmental hazards : Mn is a toxic heavy metal. Environmental considerations : Hazardot s.
Cost rniation: Costconsideration : High cost per ton
of ore processed.
Developmental status : Not developed beyond
screening test stage.
-------
TABLE B-8. DEPRESSANT: SODIUH DICUROMATE (Na 2 Cr 2 O 7 )
Basic Information: Performance, Cost,
Environmental Hazards, Operating Conditions Evaluation
Depression of pyrite : Reference (23) says dichromate Performance ! Good.
and permanganate are “two of the most effective
depressants” for pyrite. Reference (18) gives plot
of pyrite recovery (%) versus added salt (lb/ton).
Addition of 0.2 lb/ton Na,,Cr 2 0 7 .2H 2 0 gives 95%
pyrite depression [ 0.3 lb7ton gives complete depres-
sion, using 0.05 lb/ton xanthate, and 0.20 lb/ton
terpineol frother]; 100 x 200 mesh particle size,
pH unknown.
Q
Depression of other sulfide minerals : —— Selectivi y : Insufficient information.
Theoretical justification for use : ——
Environmental hazards : Cr(VI) is carcinogenic Environmental considerations : Hazardous.
heavy metal.
Cost information: Cost considerations : High cost per ton
of ore processed.
Developmental status : Not developed beyond
screening test stage.
-------
TABLE B-9. DEPRESSANT: Kr6D
Basic Information: Performance, Cost,
Environmental Hazards, Operating Conditions Evaluation
Depression of pyrite: Performance : Insufficient information.
Depression of other sulfide minerals : 10 ppm corn— Selectivity : Good.
pletely depressed ZnS, 5 ppm dep. PbS, 100 ppm CuFeS 2
and No5 2 , using 20 mg/i Iç x(a) collector, pH 8.0.
With Cu—Pb—Zn ore, obtained best selection of Cu
flot. using REX + Z — 200 coil., 0.2 kg/t Na 2 Cr,O.,,
0.05 kg/t Kr6D. Ore assay: 11.8 CuFeS 2 , 53.5 f’b ,
13.5% ZnS; product assay: 41.5 CuPeS 2 , 26.0 PbS,
L 25.9% ZnS (24,25).
Theoretical justification for use : Unknown,
Environmental hazards : —— Environmental considerations : Insuff 1—
dent information.
Cost considerations : Insufficient
information.
Developmental status : Insufficient
information.
(a) RAN pota8sium arnyl xanthate.
-------
APPENDIX C
TABLE C—i. MILLS VISITED DURING STUDY
( Identified Alphabetically Only )
and
TABLE C —2. FORM USED FOR DISCUSSION WITH
PLANT CONTACT
-------
TABLE C—i. MILLS VISITED DURING STUDY
Date of
Visit
Plant
Location
Mill Products
Title
10/29/79
A
Arizona
Cu, Mo, Concentrates
Mill Superintendent
10/30/79
B
C
Arizona
Arizona
Cu, Mo, Concentrates
Cu, Mo, Concentrates
Mill Superintendent
Mill Superintendent
10/31/79
D
Arizona
Cu Concentrates
Mill Superintendent
11/01/79
E
F
C
Utah
Utah
Utah
Cu, Mo, Concentrates
Cu, Mo, Concentrates
Cu, Mo, Concentrates
Mill Superintendent
Mill Superintendent
Mill Superintendent
11/06/79
H
I
J
K
L
Missouri
Missouri
Missouri
Missouri
Missouri
Cu, Pb, Zn,
Concentrates
Cu, Pb, Zn, Concentrates
Cu, Pb, Zn, Concentrates
Pb, Zn Concentrates
Cu, Pb, Zn, Concentrates
Assistant Director
Research
Assistant Director
Research
Assistant Director
Research
Assistant Director
Research
Mill Supertindent
11/08/79
M
N
Missouri
Tennessee
Pb, Zn, Concentrates
Cu, Zn, Concentrates
Concentrator
Supertindent
Mill Superintendent
11/09/79
0
P
Q
Tennessee
Tennessee
Tennessee
Zn Concentrates
Zn Concentrates
Zn Concentrates
Engineer
Engineer
Engineer
C—i
-------
TABLE C -2. FORJI USED FOR DSCUSSION WITH
PLANT CONTACT
Company ____________________________ Contact ____________________________ Date _____
Location _________________________ Title ____________________________ Phone No.
Mill Name __________________________
Production Data
Material Wt tlday Grade, 2 Recovery, 2
Cu Pb Zn
Feed
Copper Cone.
Lead Cone.
Zinc Cone.
Cyanide Usage
Point of Addition AmOUnt Added, lbs/ton Purpose
Discharge Data
Discharge, gpd ______________ CN in discharge, ppm _____________ Form of CN in discharge -
Is there NPDES permit? _______ Does it limit CN? ________________ To what level? _________ In compliance?
Do you have an end—of—pipe CN destruct system? ___________ If so, what process ______________________________
Feasibility of Converting
Familiar with alternate pyrite depressants? — Any experience with them? _______________________
Do you think they work as well as CN? _________________ Why? ____________________________________________________
If they could be shown to work in your mill, how long would it take to install the process? __________________
Would you be willing to make laboratory tests to verify whether alternates would work? ________________________
We would appreciate any other coussents: _____________________________________________________________________
C— 2
-------
APPENDIX D
DATA SHEETS FROM MILLS A THROUGH Q
and
DISCUSSION OF DATA OBTAINED
-------
TABLE D-l. PLANT A
Company ___________________________ Contact ___________________________ Date ____
Location Arizona Title Mill Superintendent Phone No.
Mill Name __________________________
Production Data
Material
Feed
Copper Cone.
Lead Cone.
Zinc Conc.
Cyanide tYsage
Mount Added, lbs/ton
None CN in discharge, ppm NA Porn of CN in discharge NA
permit? No Does it limit CN? NA To vhat level? NA In compliance? N.L
end—of—pipe CN destruct system? No If so, what process NA
Feasibility of Converting
Familiar with alternate pyrite depressants? Yes Any experience with them? _______________________
Do you think they work as well as CN? Maybe Why? _______________________________________________
If they could be shown to work in your mill, how long would it take to install the process? Matter of day _
Would you be willing to make laboratory tests to verify whether alternates ould work? Don’t require
We would appreciate any other cormaents: Have used Na 1 S0 3 in a heavily lined circuit at another
mill to reduce viscosity and increase throughput in grinding circuit. M±l1in and flntat-lnn
process used at has been described in a paper presented at the Gauclin Flot- rinn
Symposium, held in Las Vegas, in 1976.
Grade, Z
Cu Pb Zn
0.75 —
Vt t/day
64,000
1300—1500 28
Point of Addition
None added
Recovery, Z
84
Purpose
Discharge, gpd
Is there NPDES
Do you have an
Discharge Data
D— 1
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TABLE D-2. PLANT B
Compziny _________________________ Contact — Date 10/30/79
Location Arizona - Title Mill Superintendent Phone No. —
Mill Name —
Production Data
Material Wt tfday Grade, 2 Recovery, Z
Cu Pb Zn
Feed 92,000 0.25 —
Copper Cone. 1,250 25 90+
Lead Cone.
Zinc Cone.
Other Mo,Ag
Cyanide Usage
Point of Addition Amount Added, lbs/ton Purpose
No cyanide NA
Discharge Data
Discharge, gpd None in discharge, ppm NA Form of CN in discharge NA
Is there NPDES permit? No Does it limit CN? NA To what level? NA __ In compliance? J _
Do you have an end—of—pipe CN destruct system? No ii so, what process NA
Feasibility of Converting
Familiar with alternate pyrite depressants? Yes Any experience with them? No
Do you think they work as well as CN? No opinion Why? NA
If they could be shown to work in your mill, how long would it take to install the process? About 1 month
Would you be willing to make laboratory tests to verify whether alternates would work? No need
We would appreciate any other conunents: . .
D— 2
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TABLE D-3. PLANT C
Contact ________________________
Title Mill Sur’erlr téndent
Production Data
Date ____
Phone No.
Material
Teed
Copper Conc.
Lead Conc.
Zinc Conc.
Vt tlday
50,000* 0.5
Cyanide Usage
Point of Addition
None now used
Amount Added, lbs/ton
• NA
Purpose
1A
Discharge Data
Discharge, gpd Sanitary only CM in discharge, ppm None
Is there M1 ’DES permit? No Does it limit CN? NA _________
Do you have as end—af—PiPe CM destruct system? No If so, ______
Feasibility of Converting
Familiar with alternate pyrite depressant8? Yes Any experience with them? Other mills only -
Do you think they work as well as CM? Doubt it Why? ________________________________________________
If they could be shown to work in your nih, how long would it take to install the process? No comment
Would you be willing to make laboratory tests to verify whether alternates would work? No need now
We would appreciate any other comments: This mill has used cyanide to depress pyrite flotation.
Doesn’t need it now. If iron in feed got too high, mightgo back some cyanide.
Comment by Battelle This plant is in the throes of startup. The mill superintendent was
extremely busy and couldn’t provide much time. We checked with the Arizona EPA. The plant
has no record of CN violations. There was a complaint by a rancher but this was concerned
with the discharge of the company’s sanitary waste to a small stream.
* When in full production.
Company
Location Arizon&
Mill Name _________
Grade, Z
Cu Pb Zn
Recovery, Z
Ca 90
Form of CM in discharge
To what level? NA
what process NA
NA
In compliatiae? NA
D— 3
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TABLE D-4. PLANT D
Company ___________________________ Contact ___________________________ Date _ 10131179
Location Arizona Title Mill Superintendent Phone No. ______
Mill Name __________________
Production Data
Material Vt t/day
Peed
Copper Cone.
Lead Conc.
Zinc Conc.
Point of Addition
No cyanide used
NA
____________ Form of CN in discharge
_______________ To what level? NA
No If so, what process NA
Feasibility of Converting
Familiar with alternate pyrite depressants? Yes Any experience with them? In past with NaNS
Do you think they work as well as CN? No opinion Why? NA
if they could be shown to work in your mill, how long would it take to install the process? About 1 day
Would you be willing to make laboratory tests to verify whether alternates would work? If necessary
We would appreciate any other comeents: Mill has four lines. Could assess any reagent changes
guickly Contact gave estin ate that flotation costs at Twin Buttes are between 40 and5O cen
ner ton.
42,000
1,000
Grade, 2 Recovery, 2
Cu Pb Zn
0.9 — — —
27
Cyanide Usage
Amount Added, lbs/ton Purpose
NA
fscharge Data
Discharge, gpd No diRf4 rge CN in discharge, ppm NA
Is there NPDES permit? No Does it limit CN? — NA
Do you have an end—of—pipe CN destruct system? ___________
NA
In compliance? li.&_.
D—4
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TABLE D—5. PLANTS E, F, & C
Company __________________________ Contact __________________________ Date 11/1/79
I.ocation Utah Title Mill Supertht’endent Phone No. ______
Mill Name ___________________________
Production Data
Material Vt t/day Grade, 2 Recovery, 2
Cu Pb Zn
Feed 106,000 0.6 —
Copper Conc. 2,200 25 88
Lead Cone.
Zinc Conc.
Other Mo,Re,Au,Ag,Pt,Se cyanide Usage
Point of Addition Amount Added, lbs/ton Purpose
Discharge Data
tot a 1
Discharge, gpd Ca 23,000,000 CNIn discharge, ___________ Form of CM in discharge UK
Is there NPDES permit? Yes Does it limit CN? Yes To what level? <0.O2ppm ln compliance? —
Do you have an end—of—pipe CM destruct system? No If so, what process Caispan tried alkaline
chlorination and ozonation in lab.
Feasibility of Converting
Familiar with alternate pyrite depressants? Yes Any experience with them? Not here
Do you think they work as well as CM? ________________ Why? _________________________________________________
If they could be shown to work in your mill, how long would it take to install the process? __________________
Would you be willing to make laboratory tests to verify whether alternates would work? _________________________
We would apprecIate any other cotmeents: Three mills treat the same type of ore from the same
mine. All use the same process and supervised all three.
jihis plant was studied by Caispan who prepared the Develonmertt Document for M h 1 Mining
and Milling Industry.
D- 5
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TABLE D-6. PLANT H
pany _____________
ation Missouri
1 Name
Contact __________________________
Title Assistant Director of
— Date 11/6/79
Phone No. _____
Research
Production Data
Cyanide Usage
Point of Addition Amount Added, lbs/ton
Grind, lead & 0 to 0.05 lbs
zinc cleaner cir— ter ton of fe
cults. Sometines
not added when metallurgy
is favorable. Discharge Data
charge, gpd Essen. closed Cl in discharge, ppm < 0.02 Form of CN in discharge
there NPDES Pce tte? Yes Does it limit CN? No To what level? NA
you have an end—of—pipe CN destruct system? No If SO, what process NA
Not known
In compliance? NA
Feasibility of converting Some. Sulfites also
depress Pb and led
irnili at with alternate pyrite depressants? Yes Any experience with them? to ineonoiot ncie-e —
you think they work a well as CN? No Why? Perhaps not enough work on them
they could be shown to work in your mill, how long would it take to install the process? Depends on how niuc1
uId you be willing to make laboratory tests to verify whether alternates would work? Yes iron. Matter of
would appreciate any other con ents: These apply to other 3 plants àlsb.’ If CN were rii1 d r days
e would of course try others. So far there has been no encouragement to do so. Do not think
hat CN is a significant problem. Two streams in area are monitored monthly for cyanide. All
esults <0.02 ppm. No fish kills in area streams for 10 years. Tailing ponds max. 0.05.
) Grades and recoveries shown were given as typical for all four plants owned by the company.
) Weights of zinc concentrates were not cited because they are so variable. Copper concen-
trates not cited. Company estimated copper concentrates from all four plants to be
12,000 t/yr.
Hat erial
Feed
Copper Conc.
Lead Conc.
Zinc Conc.
Vt t/day
5000
400
?2
Crade, 2
Cu Pb Zn
0.25 5 0.8
— 72_741 —
— — 521
Fe
Ca. 1
Recovery, 2
961
701
Purpose
Pyrite depression
D— 6
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TABLE D— 7. PLANT I
Company __________________________ Contact __________________________ Date 11/6/79
j ocation Missouri Title Assistant Director of Phone No. ______
Research
Mi]i Name _________________________
Production Data
Material Wt t/day Grade, Z Recovery, Z
Cu Pb Zn
Feed 7,500 0.25 4 1
Copper Conc. — — — —
Lead Conc. 500 — 72—74 — 96+
Zinc Conc. Variable 0.5 0.8 58 83
Cyanide Usage
Point of Addition Amount Added, lbs/ton Purpose
Sometimes to grind 0 to 0.05 lb/ton Depress pyrite
and cleaner circuits ___________________
Discharge Data
closed cycle
Discharge, gpd EssentiallY CN in discharge, ppm < 0.02 ppm Form of CN in discharge Not known
Is there NPDES peri iit? Yes Does it limit CN? No T what level? NA In compliance? J _
o you have an end—of—pipe CN destruct system? No If so, what process NA
Feasibility of Converting
Familitr with alternate pyrite depressants? Yes Any e cver4ence with them? See Plant H comments
o you think thr y work as well as CN? NA Why? NA ___________________________
If they could be shown to work in your mill, how long would it take to install the process? ___________________
Would you be willing to make laboratory tests to verify whether alternates would work? _________________________
We would appreciate any other comments: See Plant H comments
D- 7
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TABLE D-8. PLANT J
Company __________________________ Contact ___________________________ Date 11/6/79
Location Missouri Title Assistant Director of Phone No. _____
Research
Mill Name ________________________
Productio _ Da
Material Vt tiday Grade, Z Recovery, X
Cu Pb
Feed 5,000 0.25 8 0.8
Copper Cone.
Lead Cone. 400 — 74 — 98
Zinc Conc. Variable — — 53 60
Cyanide Usage
Point of Addition Amount Added, lbs/ton Purpose
Grind Pb and Zn — 0 to 0.05 lb/ton Depress pyrite
cleaners ____________________ _________________
Discharge Data
closed cycle
Discharge, gpd ssentially CN in discharge, ppm < 0.02 ppm Form of CN in discharge ____
Is there NPDES Itermit? Yes Dues it limit CN? No To what level? ________ In compliance?
Do you have an nd .-of—pipe CN destruct system? No If so, what process _____________________________
Feasibility of Converting (See Plant H)
Familiar with alternate pyrite depressants? _________________ Any experience with them? ________________________
Do you think they work as well as CN? ________________ Why? __________________________________________________
If they could be shown to work in your mill, how long would it take to install the process? ___________________
Would you be willing to make laboratory tests to verify whether altern3tes would work? _________________________
We would appreciate any other comments: . .
D—8
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TABLE D-9. PLANT K
Company __________________________ Contact __________________________ Date 11—6—79
Location _ Missouri Title Assistant Director of Phone No. _______
Research
Mill Name _________________________
Production Data
Material Vt t/day Grade, Z Recovery, 2
Cu Pb Zn
Feed 2,500 0.25 2.5 <0.1
Copper Conc.
Lead Conc. 100 — 72—74
Zinc Conc.
Cyanide Usage
Point of Addition Mount Added, lbs/ton Purpose
Grind or Pb 0 to 0.05 lb/ton Depress pyrite
cleaners
Discharge Data
cycle
flischarge, gpd Essen. closed CN in discharge, ppm < 0.02 Form of CN in discharge _________________
Is there NPDES permit? Yes Does it limit CN? No To what level? ________ In compliance? —
Do you have an end—of—pipe CN destruct system? No If so, what process ____________
Feasibility of Converting (See Plant H)
Familiar with alternate pyrite depressants? _________________ Any experience with them? —
Do you think they work as well as CN? ________________ Why? —
If they could be shown to work in your mill, how long would it take to install the process?
Would OU be willing to make laboratory tests to verify whether alternates would work? _____
We would appreciate any other comments: ___________________________________________________
D- 9
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TABLE D—10. PLANT L
Company _________________________ Contact — Date 1l/ /79
Location Missouri Title Mill Superintendent Phone No. ______
Mill Name _________________________
Production Data
Material Vt t/day Crade, Z Recovery, X
Cu Pb’ Zn Fe
Feed 4,200 0.3 7 1 3 —
Copper Cone. 32 2.9 1 0.8 1.5 70
Lead Cone. 480 0.4 75 1 1.5 98
Zinc Cone. 64 0.3 1.5—2 62 — 75—80
Cyanide Uszg,e
Point of Addition Amount Added, lbs/ton Purpose
Rod mill feed 0.015 to 0.02 lbs/ton _ D n’reAs Fe and Zn
Zinc cleaner __
Discharge Data
cycle
Discharge, gpd Essen. closed CN in discharge, ppm Not detect . Form of CN in discharge —
Is there NPDES permit? Yes Does it limit CN? No To what level? — In compliance? —
Do you have an end—of—pipe CN destruct system? No If so, what process _________________________________
Feasibility of converting
Familiar with alternate pyrite depressants? Yes Any experience with them? Yes in lab
Do you think they work as well as CN? — No Thy?
If they could be shown to work in your mill, how long would it take to install the process? About a week
Would you be willing to make laboratory tests to verify whether alternates would work? Might
We would appreciate any other cousnents: Plant is highly automated with’ 10 product streams being
monitored every 3 minutes via X—ray fluorescence. Cited NaCN at 48 ulb. Based on data they
obtained reagent cost of sulfate would be 8 times that of cyanide to do the same job .
D- 10
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TABLE D—11. PLANT M
Company ___________________________ Contact — Date 11/6/79
Location Missouri Title Contractor Superintendent Phone No. _____
Mill Name
Production Data
Material Wt t/day Grade 1 Z Recovery, X
Cu Pb Zn Fe
Feed 6,500 0.2 8 2.5 2 5
copper Conc.
Lead Cone. 600 — 75 1.2
Zinc Co De. 250 — 1.4 58
Cyanide Usage
Point of Addition Amount Added, lbs/ton Purpose
Lead cleaner _ 0.01 lb/ton ‘ Depress ivrite
Discharge Data
Discharge, gpd 3500 CM in discharge, ppm < 0,02 Form of CN in discharge ___________________
Is there NPDES permit? _ fes Does it limit CM? Yes To what level? 0.02 In compliance? *
Do you have an end—of—pipe CN destruct system? ___________ If so, what process _________________________________
Feasibility of Converting
Familiar with alternate pyrite depressants? Yes Any experience with them? Limited
Do iou think they work as well as CN? Doubt ________________________________________________
If they could be shown to work in your mill, how long would it take to install the process? A year to convince
Would OU be willing to make laboratory tests to verify whether alternates would work? him
We would appreciate any other couents: .
* In winter may exceed rarely.
D—11
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TABLE D—12. PLANT N
Company __________________________ Contact ___________________________ Date 11/8/79
Location Te p sspp Title j!f r., Eng. Tn’dus. Chem . Op. Phone No. _____
Mill Name _______________________
t roduction Data
Material Wt t/day Crade, % Recovery, 2
Cu Pb Zn Fe
Feed 7,000 0.72 — 0.6 3L5 —
Copper Cone. 210 17 — — — 75
Lead Cone. — — — —
Zinc Conc. 25 — — 48—50 — 30—32
Iron 3,100 — — — 55—56 80
Cyanide Usage
Point of Addition Amount Added, lbs/ton Purpose
Copper rougher 0.1 lb/tori Depress Fe
Smaller amount to _______________ and Zn
Cu cleaner 0.06 to 0.08 lb/ton ________________
Discharge Data
Discharge, gpd 6,000 CN in discharge, ppm ___________ Form of CN in discharge __________________
Is there NPDES permit? Yes Does it limit CN? _ Yes To what level? 2 g/d compliauae?
Do you have an end—of—pipe CN destruct system? No If so, what process loading
Feasibility of Converting
Familiar with alternate pyrite depressants? Yes, sulfites Any experience with them? Yes, several yrs. ago
Do you think they work as well as c M? No Why? — Based on results
If they could be shown to work in your mill, how long would it take to Install the process? 2 or 3 days
Would you be willing to make laboraeory tests to verify whether alternates would work? __________________________
We would appreciate any other coimnents S
D- 12
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TABLE D-l3. PLANT 0
Company __________________________ Contact 0 Date 11/9/79
Location Tennessee Title Engineer Phone No. _____
Mill Name ________________________
Production Data
Material Wt t/day Grade, % Recovery, Z
Cu Pb Zn
Peed 6,500 — — 2.5
Copper Conc.
Lead Cone.
Zinc Conc. 250 — — 62.5 Ca 97—98
Cyanide Usage
Point of Addition Amount Added, lbs/ton Purpose
Ball mill feed 0.02 1/t , Depress iron
and to rou hers when needed
and cleaners
Discharge Data
Discharge, gpd Closed cycle CN in discharge, ppm ____________ Form of CN in discharge ______
Is there NPDES pe mit? Yes Does it limit CN? No To what level? ________ In compliance?
Do you have an end—of—pipe CN destruct system? No — If so, what process ____________________________
Feasibility of Converting
Familiar with alternate pyrite depressants? _________________ Any exDerience with them? _______________________
Do you think they work as well as CN? ________________ Why? _________________________________________________
If they could be shown to work in your mill, how long would it take to install the process? __________________
Would you be willing to make laboratory tests to verify whether alternates would work? ________________________
We would appreciate any other comments: Formerly used lime as depressant. By using starvation
quantities of cyanide have been able to cut iron in concentrates from about 3.0 to 0.5 percent .
D-1 3
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TABLE D-14. PLANT P
Company ___________________________ Contact ___________________________ Date 11/9/79
1.,ocation Tennessee Title Engineer Phone No. ______
Mill Name __________________________
Production Data
Material Vt t/day Grade, Z Recovery, X
Cu Pb Zn
Feed 3,200 — — 2.5
Copper Cone.
Lead Cone.
Zinc Conc. Ca 120 — — 63 96
Cyanide Usage
Point of Addition Amount Added, lbs/ton Purpose
Ball mill feed 0.02 lb/ton ‘ Jheñ ___________________
and roughers needed ’ __________________
and cleaners
Discharge Data (See Plant 0)
Discharge, gpd ______________ CN in discharge, ppm ____________ Form of CN in discharge ___________________
Is there NPDES permit? _______ Does it limit CN? — To what level? _________ In compliance?
Do you have an end—of—pipe CN destruct system? ___________ If so, what process __________________________
Feasibility of Converting (See Plant 0)
Familiar with alternate pyrite depressants? _________________ Any experience with them? _______________________
Do you think they work as well as CN? ________________ Thy? _________________________________________________
If they could be shown to work in your mill, how long would it take to install the process? _________________
Would you be willing to make laboratory tests to verify whether alternates would work? ________________________
We would appreciate any other con ents: _____________________________________________________________________
D— 14
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TABLE D-15. PLANT Q
Company ______________
Location Tennessee
Mill Name _____________
Contact
Title
Engineer
Date 11/9/79
Phone No.
Production Data
Grade, Z
Cu Pb Zn Fe
— — 2.5 263
Cyanide Usage
Cleaner
Amount Added, lbs/ton
0.02 lb/ton
Purpose
flc nreqs pp
Discharge Data
Discharge, gpd — CN in discharge, ppm < .02 Form of CN in discharge OK
Is there NPDES permit? Yes Does it limit CM? No To what level? ________ In compliance? —
Do you have an end—of—pipe CN destruct system? No If so, what process _________________________________
Feasibility of Converting
Familiar with alternate pyrite depressants? Yes, Na 2 SO 3 Any experience with them? 26 mo. lab exnerienc
Do you think they ‘work as well as CM? No Why? Based on our results
If they could be shown to work in your mill, ow long would it take to install the process? Several days
Would you be willing to make laboratory tests to verify whether alternates would work? _________________________
We would appreciate any other comments: Company is oinn to close the circuit on this mill:
Experience at other mills in the area has shown this can be done with no adverse effects from
buildup of reagents.
Material Wt t/day
Feed 1,900
Copper Cone.
Lead Conc.
Zinc Conc.
75 — — 58—59
Recovery, Z
92
Point of Addition
D—15
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APPENDIX D
DISCUSSION OF DATA OBTAINED
WESTERN MILLS
Four plants in southern Arizona and three in Utah were visited. All were
predominantly copper producers. The information they furnished is sunima—
rized and then treated individually as Plants A through G.
Plant A (Table D—l )
This is primarily a copper mill treating over 60,000 tons (54,400 metric
tons) per day of ore containing about 0.75 percent copper, and producing over
1,000 tons (900 metric tons) per day of copper concentrates at a grade of about
30 percent copper and a recovery of about 85 percent. It also produces a
by—product, molybdenum sulfide. Gold and silver are recovered from copper
concentrates after smelting and refining.
This company uses no cyanide to depress pyrite in the copper flotation
section, but does use a small amount of cyanide to depress copper in the
recovery of molybdenum sulfide from the final cleaned molybdenum concentrate.
The company has no discharge to waters of the state from the mill,
returning all excess water from tailings ponds and thickeners to the mill for
reuse. Consequently, no NPDES permit is required for the mill operation.
Battelle did not determine whether the company smelter or refinery discharged
to state waters.
•The mill superintendent was aware that sodium sulfite and sodium sulfide,
or related chemicals, could be used to depress pyrite, but had no direct ex-
perience with these for this purpose.
No flow diagram of the mill operation was on hand, but an excellent
brochure describing the operation of the mining, milling, smelting and re-
fining was provided for perusal.
Plant B (Table D—2 )
This, too, is a large copper mill in southern Arizona, producing mainly
copper, with molybdenum and silver by—products. The feed containing only
about 0.35 percent copper amounts to about 90,000 tons (81,650 metric tons)
per day. The mill produces from this about 1,300 tons (1,180 metric tons) of
copper concentrates assaying about 25 percent copper. Recovery is over 90 percent.
As is the case with Plant A, this mill does not use cyanide In its
flotation circuit for pyrite depression, has no discharge, and does not have
or need an NPDES permit.
The company spokesman estimated that if the mill were using cyanide, and
wished to substitute sulfide or sulfite for it, and was able to substantiate
the efficacy of the substitutes by thorough and definitive testing, the
D— 16
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changeover in the production mill might be accomplished in about 3 weeks to 1
month.
Plant C (Table D—3 )
ThL plant had been out of production for some time and was only now
approaching about half its capacity. The mill superintendent was extremely
busy and was able to grant only a relatively brief interview. Principal
products are copper, molybdenum, and silver. Mill feed, at normal capacity,
was about 50,000 tons (45,360 metric tons) per day with the feed running about
0.5 percent copper. Although the mill had used cyanide in the past as a pyrite
depressant, it had discontinued the practice. According to the superintendent,
it might be necessary in the future to go back to cyanide if problems should
arise from the presence of increasing quantities of pyrite in the concentrate.
He was familiar with the properties of sulfite and sulfide as depressants but
had no direct experience with them. The company has no process wastewater
discharge and no NPDES permit.
Plant D (Table D—4 )
This plant operates primarily as a copper concentrator, treating 42,000
tons/day (36,290 metric tons/day) of ore running about 0.9 percent copper. It
produces about 1,000 tons/day (907 metric tons/day) of copper concentrates at
a grade of about 27 percent copper. Recoveries are in the range of 87 to 93
percent, according to the superintendent. This is considerably higher than
the recovery figure calculated from the weights and grades of feed and concen-
trates, and it is suspected that the numbers given during the interview had
been rounded off. This plant does not use cyanide as pyrite depressant, has
no discharge and no NPDES permit. The superintendent stated that if it became
expedient to change a flotation reagent and if laboratory tests indicated the
technical and economic feasibility of doing so, it would only require about one
day’s null operation to change over.
Plants E, F, and C (Table D—5 )
These three mills treat the output of one mine. Feed to the mills amounts
to over 100,000 tons/day (90,720 metric tons/day) and has an average copper
conteut of 0.6 percent. The mills produce together over 2,000 tons/day (1,800
metric tons/day) of concentrate at an average grade of 25 percent copper.
Recovery is about 90 percent. In addition to copper, operations belonging to
the company recover molybdenum, gold, silver, selenium, platinum, paladium,
and various rhenium salts.
These mills use sodium cyanide to depress pyrite during copper flotation
at a feed rate of 0.02 lb/ton (0.0091 kg/metric ton) ot ore.
The company discharges to waters of the state from its mills and operates
under an NPDES permit. The total cyanide limitation set by the permit is
0.006 ppm. The superintendent stated that they have had no problem with the
U.S. EPA in the matter of cyanide violations. The company has an end—of—
pipe wastewater treatment system, but this is primarily to control oil,
metals, and suspended solids and does not include a cyanide destruction unit.
D- 17
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These plants were studied byithóàoiitractor for U.S. EPA who prepared
the Development Document for the Metal Mining Industry Point Source Category.
Other Arizona Contacts
To determine whether the plants visited were typical ó copper milling in
this part of the country, a callwás madeT to the head off çen of a major
mining cotnpany in the region, whIch operates three c’ nermines and mills
treating about Sb , ‘OOO toiis /day) . ui wfth h lan±s
visited, none of this company’s mills used cyanide to depress pyrite in their
copper flotation circuits.
MISSOURI MILLS
Three companies controlling six mIlls re intervieve in Missouri. All
these were primarily lead and zinc produce s with copper being a relatively
minor by—product. They are discussed individually under the designation of
Plants.H through H.
Plants H, I, J, and IC (Tables D—6 through ‘D—9 )
hese fj ji mi1ls treat from 1,200 to 7,5ô0 tons/day (1,090 to 6,800 metric’
tons/day) of ore from the parent company’s mines. Ore grades are variable. The
ranges of ore composition are as follows:
Pb — 2.5 to 8 percent
Zn — 0.1 to 0.8 percent
Cu — about 0.25 percent in all cases
— 1. to 3 percent.
The weight of concentrates produced is also variable, depending on the
feed tonnage, ore grade, etc., at the individual mills, ore characteristics,
and response to reagents. Lead concentrate tonnage ranges from 100 to 700
tons/day (9l to 635 metric tons/day) at a fairly consistent grade of over 70
percent lead. Zinc concentrate tonnages, according to the company repre-
sentative, vary “all over the lot” at a grade of about 50 to 52 percent zinc.
All four mills together produce about 15,000 tons (13,600 metric tons) of
copper concentrates. Overall recoveries cited were as follows:
Pb 96 percent
Zn — 70 percent
Cu 70 percent.
Sodium cyanide is used to depress pyrite. Cyanide additions range from
0 to .005 lb/ton (0 to 0.0023 kg/metric ton) and are made either in the grinding
step, or in the cleaning steps. On some occasions, depending on the
metallurgy, no cyanide additions at all are made at two of the four mills.
The company representative indicated that at the two other mills, with higher
iron assays, cyanide was always added and that he would hesitate to predict
the effect of not adding cyanide on the grade and composition of the lead and
zinc concentrates. lie also stated that if cyanide were ever ruled out for use
D—18
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to the mitts the pao’ ‘aould he forced to take other steps • look dt other
alternatives. Up to now, he said, they had received no impetus or envourogement
to look at other alternntives
At all four plants, recycling of water is maximIzed and, except after
heavy rains, the systems are essentially closed cycle with ar,y .uakeup being
suppfled by mine water. Discharges do occur, however, and each mill operates
under a separate NPDES permit.
Effluents from the plants consistently contain 0.02 ppm cyanide as
determined colorimetrically. Distillation Is not used in the analysis.
There is a probability therefore that co mlex cyanides (e.g., as iron
hexacyano complex Ion) may be present in mill effluents.
Five streams in the area of the plants are analyzed monthly for cyanide.
No detectable cyanide has been found In these stream samples. According to
the company’s environmental supervisor, there have been no fish kills in
these streams for at least 10 years.
The company’s assistant director of research stated that even If labora-
tory tests indicated that sulfide or sulfite could be used to supplant cyan-
ide as a depressant for Iron, its adoption would depend on the iron concen—
trat on ratio In the mill feed, and he pointed Out that in two of the four
mills iron concentrations were unpredictably variable. If proper and de-
cisive laboratory tests did indicate the feasibllIt ’ of substituting either
sulfide or sulfite for cyanide, and if the changeover were made, he expected
that the response In the production circuit could be judged, but he would not
speculate on the time it would take for the changeover to reach steady state.
Plant L (Table D—l0 )
lii is plant produces copper, lead, and zinc concentrates. It treats l ,200
n - /d v (3, 81.0 met c i c tons/day) of an ore conta i i i I ng about 7 percent lead
perccnt zinc, 0. - )C CC 1L copper, and 3 percent Lrou. me plant operates
on ii f .i ye—day/week haS s oii about 2 0 days per year.
Average daily production of concentrates is as follows:
Ph = 81) tons ( L 115 met r I c tons)
= 6 :ons (58 metric tons)
Cu = 32 tons (29 metric tons).
0— I 9
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Concentrate grades and recoveries are shown in the following tabtilat ion:
Concentrate Grades , 7
Conc€mtratesl’ b Zn Cu Fe Recovery,
Pb 75 1 0.4 1.5 97.5
Zn l.5-2.0 61.5 0.5 1.5 75—bU
Cu 4 0.8 29 28 70
Cyanide to depress both iron and zinc is added in the rod mill and the
zinc cleaner. Cyanide additions range from 0.015 to 0.02 lb/ton (0.0075 tr
.010 kg/metric ton) of feed.
The company uischacges to waters o the state and so must operate under
an NPPES per-mit. The original NPDES permit had set cyanide restrict ions at a
level below detectable limits. The present permit does not limit cyanide.
Cyanide is presently not detectable in the effluenc from the plant. This is
attributed to the small amounts of cyanide used and to the continuous analy-
sis and coinpitcrized control system employed. A company official estimated
that it would take about one week of mill op.±rat Inn to determine the effect
[ the change due to the reagent substitution.
Tbi company had tested suifitc as a depressant and stated that it had
worked in the laboratory tests. The quantity of sulfite required, however,
was quite high. The interviewed official stated t iar where annual cyanide
costs c oro 7,000 to 8,000, sulfite costs would ex eed $63,000. Doc.ioenta—
ton of these results was not provided to 9artel lu’s Columbus t.aI)ar iitO i ’ LOS.
plant N (Table I)— I Ii
Tin plant products 1e d and s inc concentrates only. It treats 6 50(1 tons!
do’: ( 5, ‘ (iQ mmcl c -i c r. ons /day ) ci I ore with an ave rag’ grade of about 8 percent
lead, 2. 5 percent ziuc, 0.2 percent cooper, and 2. 5 percent iron. Tt produces
601) tons/day (544 metric tons/day) of ic-ad concentrates containing about 75
pe runt I end and I . 2 pi’ rn -ic t rite . It a iso produc cc about 250 tons/day (227
net cii : i s/dny) of zinc eonc ’cititrflte s contair’ing SE percent zinc and 1.4 per—
cent lid C ii cu In ted recover i es , based on these data a re lead — 1)5 to 90
pe ii e ii , aid z Inc — aho cit 9u pe cc en t
Cyanide is added to the lend cleaner circuit a: a rut’.’ of about 0.01 ‘ib!
ton (C.0055 kg/metric ton) of ore Lo depress pvrite during flotation.
lime coulipaily d iscica rges was t c’wa t cr at a rate o 1 3, 500 gpm (13, 250 ii t e rs /
miii). IL. ’; N)’l)ES permit limits cyanide to 0.02 ppm. ‘ibis limitation was
c ’xcee ilt ’d only once in the pai3t several years and ou i y doting the wmuter.
Tic couii 1 ianV s pcik e noon stat cd that I t wo ul d t ak i’ a ye or of good tim 1 I
oper;ci Icmm; o ecaivi nec’. mliii that tie reagent changeover sichst it citing Sn l F icb’
or old I h’s for cyanide wits icciptiuble.
-20
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‘fENNE iS NE MI LLS
Three companies controlling Four mil is were interviewed In Tenreic-ee.
Three of these mills were zinc concentrate producers and the fourth was
pr imari I)’ an iron oxide producer with copper and zinc as coprodirts. These
ii i I Is are designated as Plaits N, 0, P, and Q.
Plant N (Table 0—12)
This plant produces zinc and copper concenttates, as well as iron sulfide
concentrates wli ich arc later roasted to oxide and eventually sold for iron
ore. The mill treats 7,000 tons/day (6,350 metric tons/day) of ore containing
about (1.6 percent zinc, 0.72 percent copper, and about 32 percent iron. The
iron in the ore occurs as pyrrhotite and pyrite in a ratio of 4:1 , respect ivelv
Its cia i l v produc tion is about. 210 tons/day (190 metric tons/day) of copper
concent rates containing from 15 to 20 percent copper, and 25 tons/dn (23
met ri c tons/day) of zinc concentrates containing about 50 percent xi no.
Approximate recoveries for copper and zinc are about 75 and 31) to 35 percent,
respect I ye 1 y.
lie company cop I o s sod ium cyanide to depress both iron and z inc adding
abet 0.1 lb/ton (0.0 /3 kg/metric ton) to the copper rougher circuit and an
auci IL i ui u1 0.06 to 0.08 Ib! ton (0.027 to 0.036 kg/met nc ton) to the copper
ci caner circuit. The elat ively high rate of cyanide addition is necessary
1)0 ca I S O I) I the hi pu i ron coot cOt of the ore
The entire piniiL discharges about 6,000 gpni (22, 7 2 liters/miti) of waste—
water to surface streams and operates under an NPDES permit. The permit limits
the discharge of citilde to 0.5 kg average and 0.7 kg maximum, per dn\ . On
tie basis of the data provided, these loadings calculate out to concentratiOnS
of about ((.015 ppm average and ;if,out 0.02 ppm maximum. These limits arc not
coi’s latent
The company had ives t igri i ed s u if I t e s or hi s : if I t es as de press at I some
years ago, aid the spokesman st:ated that the program did not wock Out too
we I I’ It sn s ta t ed ha t it WOuld he di ff1 c t Ii to s intu late the I r copper.
clrcII I in laboratory tests. lt was estimated that if the mill circuit were
hanged from cyanide to sulfite or sulfide for iron de )ression, ii would only
abe 2 or 3 (lays to eval a te the workability of I lie change hut that it
prHaI )lv would take sever ii months to fine—tune the system (i.e. , maximiz e
a i’, ci e of I he 150 i t ed F r ac Ions
‘1 a (I an ci I’ ( Tab 1 us 0— 1 3 aid 0—1 4)
ho th of these plants are tempo tar ii y shut down and are undergo i ng some
revision in equipment. Plan’ 0. when operating, treats 6,200 to 6 50() Ions
(3,625 to 5,900 metric tons) c ore per day containing 2. 5 percent z 1110. it
produce ; about 250 tons/day (227 metric tons/day) of zinc concentrates at a
grade (if 62.5 percent zinc at a recovery of 07 to 08 percent. This iii
employs heavy media separalioii prior to flotation. aid the Iced to fit it ton
is Lhe by upgraded to ahotit 5 percent zinc.
-------
Cyanide addition, amounting to about 0.02 lb/ton (0.0091 kg/metric Eon) of
original Iced, is made to hail mill feed or to the zinc: rougher or cleaner
circuits, when needed, which is only part of the t jim.
The mill is opera tcd in compi ete closed circuit and, according to
c l i icials , there is no cyanide discharge. Recycling doe -s not result in ii
huildup cl collectors in the circuit. Frothers do huild up, hut this is
rcga rded as an a vantage
Plant P treats, when operating, 3,200 tons/day (2,900 metric tons/day)
of ore containing 2.5 percent zinc, and produces about 120 tons/day (109 metric
tons/day) of zinc concentrate containing about 63 percent zinc at a recovery
of 96 percent
No cyanide is used in this mill.
Plant Q (Table D—15 )
‘ [ ‘his plant treats 1,900 tons/day (1,724 metric: tons/day) of zinc ore
containing 2.5 percent zinc and 2.3 percent iron. It produces 75 tons/day
(68 metric tons/day) of zinc concentrates at grade of about 59 percent zinc
and at a recovery of about 92 percent.
Cyanide is not used at present hut has been used. Cyanide additior, when
it was made to the zinc cleaner circuit, was only about 0.02 lb/ton (0.091
kg/metric ton) of feed.
The compary operates under an NPDES permit which does not place limita-
tions on cyanide. It is possible that cyanide may he used In the future, but
the company is intending to close the mill circuit and eliminate mill dis—
c ha r ge
Staff members have experimented iii the laboratory iii the past with sodium
sulfite as a d”pressant For pyr ite and have found that it has not improved
grade or recovery over those obta ir ,a5le with no depressants.
The compa ny S poke sman es t I inn t c c l t ha t I t would La kc’ about 2 days of in ii I
opera’ on to assess the value of reagent changes in the nfl I, but that a
longer t line would be needed to fine—tune the circuit.
D—22
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A.PPENr IX E
‘LOWSHEETS OF TYPICAL MILLIN( ; OPERATIONS
-------
PRIMAR Y FLOTAT ON CIRCUIT FLOWSNEET
FT(; RE E- I PLANT B - ARIZONA (COPPER)
E—1
MOLY PLANT
-------
m Geinding Ci oit
I
40 Rows No 66
10 Ciii Fag.rgr .rss ______ ______
Ro. Cone (lit 4 C.lis( $CQV. Conc (t sl 6 C.Iii ) ________
Final toils
8 Row No. 66
10 C. Fog. grins 3 Tistck.neri
Und irf low
—
3 Kr.bs 0 205 Cycien.s
OV .,fll?W Un l.r iow
8’ A C. e,uii Mill Con. From
Firil C ____________
IC Ciii No. 24 0.nv.,s Miii Ii
Conc Toils
T
Sicond Ci.anir 4 Rows Middling I Row
10 Ciii No 24 D.nwsrs 15 Ciii No. 120 A
Agitair
jails Cone
jails
3 r. 20 S Cyclon.
Third Ci.an., 2 Rows
10 Cii rio. 24 D.nv.r 4
OvirfIow Und.rflcw
Canc. Toils - I c
-r i .
I 50’ Th ;..n.r 9 x 18’ AC. 8 il Mill
L *
MoIybd.num Plant
C nc. Tots I 5 I I Fill I Disc. jilt.,
Dio.z 14’ Foci 8’—IO ” s 10 Diic.
Roil Cars
14U1 I Flotat.iuti liowthe t
2
FI VRE E—2 PL.\NT C — ART7.t ”)NA CC PER)
-------
kD* CoyT COP CC P(8 ATt - UTAH COPPIR
IIIIIEE E I p i .t
(pnm.ry collecto l
FrotM
IMIBC_c,eIvllC
A cyanldB
I ’m, — 8.1 -9.0
No. I Fuel Oil
(Sc. enge
F,oII e,
Scav. Cl,an ,
G.nm.l MIII Ia l nç Ti.Irng
COPPER FLOJATIOP CIRCUIT FLOWSHEEI
J T(i ‘H H i:- ‘3. PLANT C — UTAH (CflPPVP)
E—3
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I’IGURE E—4
F lowsheet of the Magrnont Concentrator
PLANT L - MISSOURI (COPPER—LEAD—ZINC) 4
U— 4
-------
:7 ,
—--—----——— —-.
I 7tc
L
LJ
t_ ____________ _ - .
! !S • - —
CS.n%3.
(;:
0 •
FICURE E-S. PLANT N - MISSOURI (LEAD-ZINC) 5
-------
TO P.Ir ( FILL
F LO TAT ION
IMLI
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--
CAt, ( II ( I tTiO;OL
PCLLETI/(NG PLANr
LII S
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L J
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C I (‘,UM PolIt)
FL 6101 .1 LOG
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f- UNClCit’
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c -oh R I Q
t .OI O.
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fr 1 Y. ’
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6L Iii I L A TILt
981. Ux1tL
OL LIJM
OL Gt t flC CH [ IIICAIS
F’TGL RE E—6. PLANT N — TENNESSEE (COPPER-ZINC—IRON) 5
LI AOL
L - ’ J
CUl l 01 4 I NO
C O tt C
M IN £ S
POWE l l GENERAT ING
f JEt
Lit N
ST £4 M
L -
81 STill
COPPt P
I (d S It C ( <‘I
OtOT
C U IlL A
GA O C i ANING
Acli) t 1.ANrS
C- 1)
-
_—; o
rJJT i
_S l l __
•-• ::‘ I.’
Silt Ut4ATtO
1) IC. . ‘.I C S
E— 6
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I IBLIOCRAPHY
l’1ot jt ion, A. N. Caudin Ncmori i1 Volume, N. C. Fuerstenau, Editor, Voi e
‘, American Institute of Miiiing, Metallurgical, and Petroleum Engineers,
Inc., New York, 1976, p. 1116.
2. Ihid. , pp 1096—1097.
3. Ibid., p. 1070.
. Ibid., p. 1219.
5. Furnished by interviewee.
F:— 7
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