U.S. patent application number 13/013578 was filed with the patent office on 2012-02-02 for metathetic copper concentrate enrichment.
This patent application is currently assigned to Polymet Mining Corp.. Invention is credited to David Bruce Dreisinger.
Application Number | 20120027652 13/013578 |
Document ID | / |
Family ID | 45526949 |
Filed Date | 2012-02-02 |
United States Patent
Application |
20120027652 |
Kind Code |
A1 |
Dreisinger; David Bruce |
February 2, 2012 |
METATHETIC COPPER CONCENTRATE ENRICHMENT
Abstract
In one aspect, the invention provides processes for producing an
enriched copper concentrate from a copper-and-nickel-containing
ore. Processes of the invention may include an initial step of
comminuting the ore, to provide a ground ore comprising copper
minerals and nickel minerals. The ground ore may be subjected to a
floatation process, to separate the ground ore into distinct
fractions, such as first and second concentrates. A first
concentrate may for example be made up of
copper-enriched-and-nickel-containing solids, while a second
concentrate is made up of nickel-enriched-and-copper-containing
solids. The floatation process may for example fractionate the ore
so that the concentration of copper minerals is higher in the first
concentrate than in the ore, and the concentration of the nickel
minerals is higher in the second concentrate than the ore.
Inventors: |
Dreisinger; David Bruce;
(Delta, CA) |
Assignee: |
Polymet Mining Corp.
Richmond
CA
|
Family ID: |
45526949 |
Appl. No.: |
13/013578 |
Filed: |
January 25, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61341632 |
Apr 1, 2010 |
|
|
|
Current U.S.
Class: |
423/26 |
Current CPC
Class: |
Y02P 10/236 20151101;
Y02P 10/20 20151101; C22B 15/0008 20130101; C22B 15/0069 20130101;
C22B 11/04 20130101; C22B 15/0089 20130101; B03D 1/02 20130101;
C22B 15/0071 20130101 |
Class at
Publication: |
423/26 |
International
Class: |
C22B 15/00 20060101
C22B015/00 |
Claims
1. A process for producing an enriched copper concentrate from a
copper-and-nickel-containing ore, comprising: comminuting the ore
to provide a ground ore comprising copper minerals and nickel
minerals; subjecting the ground ore to a floatation process, to
separate the ground ore into a first concentrate comprising
copper-enriched-and-nickel-containing solids and a second
concentrate comprising nickel-enriched-and-copper-containing
solids, wherein the concentration of the copper minerals is higher
in the first concentrate than in the ore and the concentration of
the nickel minerals is higher in the second concentrate than the
ore; subjecting the second concentrate to a hydrometalurgical
extraction, to extract a copper-containing leachate from the second
concentrate; and, exposing the first concentrate to the
copper-containing leachate under metathetic leaching conditions
that are effective to increase the concentration of copper, and
decrease the concentration of nickel, in the
copper-enriched-and-nickel-containing solids, to provide the
enriched copper concentrate.
2. The process of claim 1, wherein the copper mineral and nickel
minerals are selected from the group consisting of: CuS, covellite;
Cu9S8 (Cu1.12S), yarrowite; Cu39S28 (Cu1.39S) spionkopite; Cu8S5
(Cu1.6S), geerite; Cu7S4 (Cu1.75S), anilite; Cu9S5 (Cu1.8S),
digenite; Cu31S16 (Cu1.96S), djurleite; Cu2S, chalcocite; CuFeS2,
Chalcopyrite; Cu5FeS4, Bornite; CuFe2S3, Cubanite; Ni3S4,
Polydymite; NiS, Millerite; Ni3S2, Heazelwoodite; FeNi2S4,
Violarite; Ni4.5Fe4.5S8, Pentlandite; Fe(Ni)7S8, Nickeliferrous;
and Pyrrhotite.
3. The process of claim 1 or 2, wherein the metathetic leaching
conditions are optimized for maximum copper depletion from the
copper-containing leachate.
4. The process of claim 1 or 2, wherein the metathetic leaching
conditions are optimized for maximum enrichment of copper
concentration in the enriched copper concentrate.
5. The process of any one of claim 1 or 2, wherein the average
particle size of the copper-enriched-and-nickel-containing solids
subjected to the metathetic leaching conditions is less than 100
.mu.m.
6. The process of any one of claim 1 or 2, wherein the average
particle size of the copper-enriched-and-nickel-containing solids
subjected to the metathetic leaching conditions is in the range of
5-30 .mu.m.
7. The process of any one of claim 1 or 2, wherein the metathetic
leaching conditions comprise an average temperature in the range of
ambient temperature to boiling point.
8. The process of any one of claim 1 or 2, wherein the metathetic
leaching conditions comprise an average temperature above boiling
point.
9. The process of any one of claim 1 or 2, wherein the metathetic
leaching conditions are maintained for a metathetic leaching time
in the range of 2 to 12 hours.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This invention claims the benefit of U.S. Provisional Patent
Application No. 61/341,632, filed Apr. 1, 2010, the contents of
which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention is in the field of hydrometallurgy, and
provides methods for processing of copper-nickel-cobalt sulphide
ores that may contain precious metal values.
BACKGROUND OF THE INVENTION
[0003] Sulphide ores of copper-nickel-cobalt are normally treated
by multi-stage crushing, grinding and flotation to produce separate
copper and nickel-cobalt concentrates that may then be smelted. A
wide variety of mineral processing procedures can be used to
separate the copper and nickel containing minerals, such as
chalcopyrite (CuFeS.sub.2), cubanite (CuFe.sub.2S.sub.3),
pentlandite (Ni.sub.4.5Fe.sub.4.5S.sub.8) and pyrrohotite
(Fe.sub.7S.sub.8) which are typically present in
copper-nickel-cobalt-precious metal sulphide ores.
[0004] A typical grade of copper concentrate would be 25-35% Cu. If
the grade of copper is low (for example less than 25% Cu) then the
concentrate may be less desirable and may incur higher costs for
smelting or alternately may not be accepted by smelters. It is thus
generally desirable to maximize the grade of copper in the copper
concentrate, and accordingly to produce copper concentrates having
relatively low levels of nickel and cobalt. Elevated levels of
nickel in copper concentrates, for example in the range of 0.2 to
1.0% Ni, may adversely impact copper anode refining processes. High
levels of nickel in the copper anode may for example cause anode
passivation during refining. In addition, nickel contained in
copper concentrates is often not paid for by copper smelters.
[0005] Similarly, in the production of a nickel sulphide
concentrates for nickel smelting, a minimum grade of at least 4% Ni
is generally desirable, and higher Ni levels are often attractive.
The Cu content of nickel concentrates may be significant, but
generally it is desirable to have a Cu content less than that of
Ni.
[0006] There are a very wide range of options for
hydrometallurgical treatment of copper concentrates to extract
metal values, including the Activox.TM. Process, the Albion.TM.
Process, the CESL.TM. Process, the BIOCOP.TM. Process, the
MINTEK-Bactech.TM. Biological Leaching Process, the Anglo American
Corporation--University of British Columbia Process, the
Galvanox.TM. Process, the Total Pressure Oxidation Process, the
Dynatec.TM. Process and the PLATSOL.TM. process (Dreisinger, 2006).
A number of chloride based processes are also available, including
the INTEC.TM. Copper Process, the Outotec.TM. Hydrocopper Process
and the Sumitomo Copper Process. These processes are generally
adapted to leach copper and other metals (such as nickel, cobalt
and zinc) from a sulphide ore or concentrate feed materials. The
metals that are leached may then be recovered from solution using a
wide range of downstream technologies for metal separation and
recovery (for example solvent extraction and electrowinning of
copper, nickel and cobalt). A similarly wide range of technologies
is available for hydrometalurgical treatment of nickel sulphide
concentrates, which may be adapted to dissolve nickel and
associated metals from the sulphide ore or concentrate, to be
followed by separation and recovery of individual metals.
[0007] U.S. Pat. No. 6,315,812 provides an example of
hydrometalurgical processes for the treatment of ores or
concentrates, and is a useful illustration of a process that may be
appropriate for concentrates containing significant precious metal
values, the PLATSOL.TM. process.
[0008] The PLATSOL.TM. process may be adapted to provide a one-step
treatment of mixed copper-nickel-cobalt-platinum-palladium-gold
concentrates, using total pressure oxidation in the presence of a
halide salt (e.g. sodium chloride). The chemistry of the
PLATSOL.TM. process can be divided into the main chemistry of
sulphide mineral oxidation and the minor (but economically
significant) chemistry of precious metal extraction. The mineral
forms of copper, iron, nickel, cobalt and precious metals may be
complex and varied, depending on the genesis of the natural ore
source. In a purely illustrative example, subjecting a concentrate
to PLATSOL.TM. leaching may be understood to dissolve copper,
nickel and cobalt, as the soluble metal sulphate salts, and
platinum, palladium and gold as the chloro-complexed species, as
shown below.
[0009] Sulfide Mineral Oxidation for Base Metal Extraction
CuFeS.sub.2+4.25O.sub.2+H.sub.2O=CuSO.sub.4+0.5Fe.sub.2O.sub.3+H.sub.2SO-
.sub.4
FeS.sub.2+3.75O.sub.2+2H.sub.2O=0.5Fe.sub.2O.sub.3+2H.sub.2SO.sub.4
Fe.sub.7S.sub.8+17.25O.sub.2+8H.sub.2O=3.5Fe.sub.2O.sub.3+8H.sub.2SO.sub-
.4NiS+2O.sub.2=NiSO.sub.4
[0010] Precious Metal Extraction
Au+0.75O.sub.2+4HCl=HAuCl.sub.4+1.5H.sub.2O
Pt+O.sub.2+6HCl=H.sub.2PtCl.sub.6+2H.sub.2O
Pd+0.5O.sub.2+4HCl=H.sub.2PdCl.sub.4+H.sub.2O
[0011] The recovery of precious metals from the PLATSOL.TM. process
may be accomplished by a number of different routes. One route
involves sequential reduction of any residual ferric sulphate
present followed by reductive precipitation of precious metals on a
synthetic copper sulphide precipitate, as shown below.
[0012] Ferric Reduction and Gold, Platinum and Palladium
Precipitation
Fe.sub.2(SO.sub.4).sub.3+SO.sub.2+2H.sub.2O=2FeSO.sub.4+2H.sub.2SO.sub.4
2HAuCl.sub.4+3CuS+3H.sub.2SO.sub.4=2Au+3CuSO.sub.4+8HCl+3S
H.sub.2PtCl.sub.6+2CuS+2H.sub.2SO.sub.4=Pt+2CuSO.sub.4+6HCl+2S
H.sub.2PdCl.sub.4+CuS+H.sub.2SO.sub.4=Pd+CuSO.sub.4+4HCl+S
[0013] Similarly, the recovery of copper, nickel and cobalt from
the precious-metal free solution may be accomplished by a variety
of technologies, including copper solvent
extraction-electrowinning, nickel and cobalt precipitation.
SUMMARY OF THE INVENTION
[0014] In one aspect, the invention provides processes for
producing an enriched copper concentrate from a
copper-and-nickel-containing ore. These ores may for example
include disseminated or massive sulphide ores of copper, nickel and
cobalt. Processes of the invention may include an initial step of
comminuting the ore, to provide a ground ore comprising copper
minerals and nickel minerals, such as: CuS, covellite; Cu9S8
(Cu1.12S), yarrowite; Cu39S28 (Cu1.39S) spionkopite; Cu8S5
(Cu1.6S), geerite; Cu7S4 (Cu1.75S), anilite; Cu9S5 (Cu1.8S),
digenite; Cu31S16 (Cu1.96S), djurleite; Cu2S, chalcocite; or,
Copper-iron-sulfide minerals, such as the following: CuFeS2,
Chalcopyrite; Cu5FeS4, Bornite; CuFe2S3, Cubanite; or, Nickel
minerals with sulphur, such as: Ni3S4, Polydymite; NiS, Millerite;
Ni3S2, Heazelwoodite; or, nickel--iron--sulphide minerals, such as:
FeNi2S4, Violarite; Ni4.5Fe4.5S8, Pentlandite; Fe(Ni).sub.7S8,
Nickeliferrous; or Pyrrhotite.
[0015] The ground ore may be subjected to a floatation process, to
separate the ground ore into distinct fractions, such as first and
second concentrates (Wills' Mineral Processing Technology, Seventh
Edition, 2006: An Introduction to the Practical Aspects of Ore
Treatment and Mineral Recovery, Napier-Munn and Wills; The Winning
of Nickel, 1967, J. R. Boldt). A first concentrate may for example
be made up of copper-enriched-and-nickel-containing solids, while a
second concentrate is made up of
nickel-enriched-and-copper-containing solids. The floatation
process may for example fractionate the ore so that the
concentration of copper minerals is higher in the first concentrate
than in the ore, and the concentration of the nickel minerals is
higher in the second concentrate than the ore.
[0016] The nickel-enriched second concentrate from the floatation
step may be subjected to one or more hydrometalurgical
extraction(s), to extract, among other things, a copper-containing.
This copper-containing leachate may then be used under metathetic
leaching conditions to treat the first concentrate, so as to
increase the concentration of copper, and decrease the
concentration of nickel, in the
copper-enriched-and-nickel-containing solids of the first
concentrate. This metathetic leaching step thereby provides an
enriched copper concentrate.
[0017] In alternative aspects of metathetic leaching optimization
steps, the process may be optimized for maximum copper depletion
(to remove as much copper as possible from the remaining nickel and
cobalt in solution); alternatively, the process may be optimized
for maximum enrichment (to optimize enrichment of the concentrate
in copper). In alternative embodiments, the operating parameter may
be selected on the basis of an overall economic optimization of the
final outcome. In general, the requirements for the metathetic
leach are to provide a suitable ratio of copper in solution to
`active` metals in the solid phase (e.g. Fe, Ni, Co). In general,
for copper removal, this number should be as low as possible (to
maximize the driving force for removal of copper from solution). In
general, for copper enrichment, this number should be as high as
possible. Other parameters that may be adjusted in metathetic
leaching steps are: Particle size--finer particles optimize
leaching (in selected embodiments, generally less than 100 um and
preferably in the P80 range of 5-30 um; Temperature--the kinetics
will generally be controlled by solid state diffusion in the
mineral phase (copper diffuses in and the other metals diffuse
out), accordingly, temperature will generally be in the range of
room temperature to boiling point (in alternative embodiments, to
maximize kinetics, the temperature of metathetic leaching may be
raised beyond the boiling point in a pressurized system); Time--in
selected embodiments, the time for copper depletion/copper
enrichment will typically be in the range of 2-12 hours, depending
on other conditions.
[0018] In selected embodiments, the invention provides metathetic
leaching steps that afford a relatively wide range of options for
tailoring the outputs of a process to accommodate variability in
earlier foatations steps. In this way, the overall process may be
adapted for economic efficiencies by modulating the floatation
parameters and the metathetic leaching parameters in concert.
Processes of the invention may accordingly include steps of
optimizing the combination of floatation and metathetic leaching
parameters.
[0019] In various aspects, the invention relates to a combination
of mineral processing steps (such as crushing/grinding/flotation)
and hydrometallurgical treatments, which in combination may be
adapted to produce a copper concentrate of improved quality. The
enrichment of the copper concentration in the concentrate may, for
example, facilitate subsequent steps, such as copper smelting.
[0020] At least one portion of nickel concentrate may be treated
under conditions designed to leach base and precious metals. For
example, adaptations of the PLATSOL.TM. process may be used (U.S.
Pat. No. 6,315,812). In selected embodiments, precious metals (such
as Au, Pt, Pd, Rh, Ir, Ru, Os, and/or Ag) may be leached from the
concentrate using such a process, and may then be recovered, for
example by precipitation on a reducing sulfide mineral (such as
synthetic CuS).
[0021] Copper leached from the nickel concentrate, for example
using PLATSOL.TM. conditions, may then be used to enrich the copper
content of a copper concentrate by metathetic leaching,
simultaneously displacing other metals from the copper concentrate,
such as nickel, cobalt and iron. By this method, it has been found
possible to synthesize a superior copper concentrate for smelting
treatment.
[0022] In some embodiments, precious metals may be co-extracted at
the same time as base metals in a primary hydrometallurgical step
(such as an adaptation of the PLATSOL.TM. process). In this way,
processes of the invention may be adapted to either recover the
precious metals in a separate concentrate, or alternatively, in a
metathetic leaching step, to allow the precious metals to
precipitate with the copper into an enriched copper concentrate. In
these embodiments, the invention provides an enriched
copper--precious metal containing concentrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a flowsheet that shows the copper concentrate
enrichment process in relation to a primary flotation process and
the hydrometallurgical treatment of all or a portion of one or more
of the nickel--copper concentrates under conditions designed to
extract precious metals. The precious metals are recovered in this
instance prior to the copper concentrate enrichment process.
[0024] FIG. 2 is a flowsheet that shows the copper concentrate
enrichment process in relation to a primary flotation process and
the hydrometallurgical treatment of all or a portion of one or more
of the nickel--copper concentrates under conditions designed to
extract precious metals. The precious metals are recovered in this
instance in the copper concentrate enrichment process resulting in
a copper concentrate that is also enriched in precious metals.
DETAILED DESCRIPTION OF THE INVENTION
[0025] FIG. 1 is a flowsheet illustrating an embodiment that
provides a precious metal product separately from an enriched
copper concentrate. In the illustrated embodiment, the flotation
circuit is used to produce up to five products, including a copper
concentrate, a scavenger tailing (to waste disposal), and a range
of nickel containing products comprising a copper rougher tail, a
copper cleaner scavenger tail and a scavenger concentrate. One or
more of the nickel concentrates (in whole or in part) is then
directed to the direct leaching process for the nickel-copper
concentrate in order to extract nickel, cobalt and associated base
metals and precious metals. The direct leaching residue is then
separated from the leach solution, washed and discarded to waste.
The leachate, containing nickel, copper and other base metals is
then subjected to a precious metal recovery step in which the
precious metals are substantially removed from solution. The
precious metal free solution then advances to the copper
concentrate enrichment process.
[0026] In the embodiment of FIG. 1, all or a portion of the copper
concentrate derived from the bulk flotation is contacted with the
precious metal free solution in order to enrich the copper
concentrate by metathetic leaching. Examples of the chemical
reactions corresponding to metathetic leaching are listed below.
These putative reactions are illustrative of conditions that
provide for the metathetic substitution of copper for any of iron,
nickel and/or cobalt in the sulphide mineral solids. Other sulphide
minerals, if present may also show similar replacement.
CuFeS.sub.2+CuSO.sub.4=2CuS+FeSO.sub.4
CuFe.sub.2S.sub.3+2CuSO.sub.4=3CuS+2FeSO.sub.4
FeS+CuSO.sub.4=CuS+FeSO.sub.4
Fe.sub.7S.sub.8+7CuSO.sub.4=7CuS+S+7FeSO.sub.4
NiS+CuSO.sub.4=CuS+NiSO.sub.4
Ni.sub.4.5Fe.sub.4.5S.sub.8+9CuSO.sub.4=8CuS+Cu+4.5FeSO.sub.4+4.5NiSO.su-
b.4
CoS+CuSO.sub.4=CuS+CoSO.sub.4
[0027] In alternative embodiments, metathetic leaching may take
place in a chloride leach environment, in which copper chloride
takes the place of copper sulphate in reactions analogous to the
foregoing reactions.
[0028] FIG. 2 shows an alternate embodiment, in which the
metathetic copper concentrate enrichment process is combined with
the precious metal recovery step. The precious metals are reduced
into the copper concentrate by the reaction of the dissolved
precious metal (for example as sodium or acid chloride complexes),
in accordance with the following putative reactions:
2NaAuCl.sub.4+3CuFeS.sub.2=2Au+3CuS+3FeCl.sub.2+2NaCl+3S
2HAuCl.sub.4+3CuFeS.sub.2=2Au+3CuS+3FeCl.sub.2+2HCl+3S
Na.sub.2PdCl.sub.4+CuFeS.sub.2=Pd+CuS+FeCl.sub.2+2NaCl+S
H.sub.2PdCl.sub.4+CuFeS.sub.2=Pd+CuS+FeCl.sub.2+2HCl+S
Na.sub.2PtCl.sub.6+2CuFeS.sub.2=Pt+2CuS+2FeCl.sub.2+2NaCl+2S
H.sub.2PtCl.sub.6+2CuFeS.sub.2=Pt+2CuS+2FeCl.sub.2+2HCl+2S
[0029] In the alternative embodiment of FIG. 2, the copper
concentrate is enriched in both copper and precious metals, whilst
being depleted of other metals, such as iron, nickel and/or
cobalt.
[0030] Although various embodiments of the invention are disclosed
herein, many adaptations and modifications may be made within the
scope of the invention in accordance with the common general
knowledge of those skilled in this art. Such modifications include
the substitution of known equivalents for any aspect of the
invention in order to achieve the same result in substantially the
same way. Numeric ranges are inclusive of the numbers defining the
range. The word "comprising" is used herein as an open-ended term,
substantially equivalent to the phrase "including, but not limited
to", and the word "comprises" has a corresponding meaning. As used
herein, the singular forms "a", "an" and "the" include plural
referents unless the context clearly dictates otherwise. Thus, for
example, reference to "a thing" includes more than one such thing.
Citation of references herein is not an admission that such
references are prior art to the present invention. Any priority
document(s) and all publications, including but not limited to
patents and patent applications, cited in this specification are
incorporated herein by reference as if each individual publication
were specifically and individually indicated to be incorporated by
reference herein and as though fully set forth herein. The
invention includes all embodiments and variations substantially as
hereinbefore described and with reference to the examples and
drawings.
EXAMPLES
Example 1
Copper Concentrate Enrichment by Contact with a Synthetic
Nickel-Copper Leach Solution
[0031] A copper concentrate obtained from a copper-nickel bulk
cleaner flotation circuit with a copper/nickel separation process
was contacted with a synthetic nickel-copper leach solution. The
copper concentrate had the analysis shown in the table below.
TABLE-US-00001 TABLE 1 Copper concentrate analysis Analysis (%) Cu
Ni Co Fe S Copper 22.8 0.47 0.035 31.9 28.7 Concentrate
[0032] 160 g of copper concentrate (dry basis) were contacted with
1200 mL of nickel-copper leach solution containing 10 g/L Cu, 15
g/L Ni, 1.9 g/L Fe and 102 g/L H.sub.2SO.sub.4. Contact was
performed in a stirred reactor for 8 hours at 100 C. The solution
was sampled during the course of the test and after 8 hours the
remaining solids were filtered and washed.
TABLE-US-00002 TABLE 2 Copper Concentrate Enrichment Test Results
Amount H.sub.2SO.sub.4 Assay (g/L or % for solids) Product (mL, g)
(g/L) Cu Ni Fe Co S 0.5 h soln 40 75 10.9 15.9 5.0 1 h soln 39 74
10.1 15.6 5.4 2 h soln 39 74 5.97 15.8 8.52 4 hr soln 37 72 1.06
15.2 11.6 8 hr soln 1113 68 0.0002 14.8 12.8 Wash soln 700 0.13
1.18 1.04 Enriched 150 30.7 0.41 24.4 0.031 27.8 Concentrate
[0033] The copper concentrate was enriched from 22.8 to 30.7% Cu
whilst the Ni, Fe and Co were reduced to 0.41, 24.4 and 0.031%
respectively. The enriched copper concentrate was regarded as
highly saleable due to the +25% Cu content and reduced nickel
contamination. Virtually all the copper in solution was removed
into the solid phase by the enrichment process by the end of the 8
hr period demonstrating the effectiveness of the copper concentrate
enrichment process.
Example 2
Nickel-Copper Concentrate Hydrometallurgical Extraction Followed by
Copper Concentrate Enrichment by Contact with the Nickel-Copper
Leach Solution
[0034] A sample of nickel-copper concentrate was obtained from a
flotation test in which a bulk copper-nickel concentrate was
subjected to copper-nickel separation. The copper rougher tails and
the copper cleaner scavenger tails were combined to form the
nickel-copper concentrate. The nickel concentrate had the analysis
shown in the table below.
TABLE-US-00003 TABLE 3 Nickel-Copper Concentrate Analysis Analysis
(% or g/t) Cu Ni Co Fe S S.sup.2- Mg Pt Pd Au Nickel-Copper
Concentrate 4.82 4.78 0.25 37.8 25.1 22.0 1.89 4.06 12.4 0.71
[0035] A pressure leach of the nickel-copper concentrate was
conducted under PLATSOL.TM. leach conditions of 225 C, 100 psig
O.sub.2, 10 g/L Cl addition for 120 minutes in a 2 L PARR titanium
autoclave. A total of 200 g of nickel--copper concentrate was mixed
with 1032 mL of solution containing (initially) 11 g/L
H.sub.2SO.sub.4, 12 g/L Ni, 0.58 g/L Cu, 1.78 g/L Fe, 1.9 g/L Zn,
1.8 g/L Mg, 4.4 g/L Al and 6.4 g/L Na.
[0036] The products of the PLATSOL.TM. testing were [0037] (a) 1025
mL of solution analyzing 71 g/L H.sub.2SO.sub.4, 21.5 g/L Ni, 10.5
g/L Cu, 11.2 g/L Fe, 2.1 g/L Zn, 0.49 g/L Co, 4.0 g/L Mg, 1.3 g/L
Al, 1.84 g/L Na, 0.09 mg/L Au, 0.65 mg/L Pt and 2.0 mg/L Pd. [0038]
(b) 700 mL of wash solution containing 3.95 g/L Ni and 1.99 g/L Cu
[0039] (c) 196 g of leach residue containing 0.12% Ni, 0.027% Cu,
30.1% Fe, 0.04% Zn, <0.002% Co, 0.73% Mg, 3.39% Al, 0.14 g/t Au,
0.13 g/t Pt and 0.47 g/t Pd. Based on these values, the extraction
of various elements was calculated to be 97.5% Ni, 99.5% Cu, 99.2%
Co, 80.7% Au, 96.9% Pt and 96.3% Pd. The calculation was based on a
comparison of concentrate feed to residue analysis.
[0040] A copper concentrate obtained from a copper-nickel bulk
cleaner flotation circuit with a copper/nickel separation process
was contacted with a portion of the PLATSOL.TM. leach extraction
produced by the method above. The copper concentrate had the
analysis shown in the table below.
TABLE-US-00004 TABLE 4 Copper Concentrate Analysis with Precious
Metals Values Analysis (% or g/t) Cu Ni Co Fe S Au Pt Pd Copper
Concentrate 22.8 0.47 0.035 31.9 28.7 2.0 1.6 6.0
[0041] 108 g of copper concentrate (dry basis) were contacted with
780 mL of PLATSOL.TM. leach solution. Contact was performed in a
stirred reactor for 8 hours at 100 C. The solution was sampled
during the course of the test and after 8 hours the remaining
solids were filtered and washed.
TABLE-US-00005 TABLE 5 Copper Concentrate Enrichment Test Results
with Precious Metals in Solution Amount H.sub.2SO.sub.4 Assay (g/L
or % or g/t for solids) Product (mL, g) (g/L) Cu Ni Fe Co S Au Pt
Pd 0.5 h soln 29 65 13.8 21.6 16.6 0.44 1 h soln 23 65 13.2 21.0
16.4 0.42 2 h soln 29 65 11.7 21.0 17.5 0.44 4 hr soln 29 65 5.67
21.7 22.3 0.45 8 hr soln 594 66 0.001 21.8 27.2 0.45 <0.01
<0.01 <0.01 Wash soln 970 0.012 0.87 1.08 0.019 Enriched
Concentrate 98 32.3 0.45 23.3 0.037 30.8 2.84 6.36 22.8
[0042] The copper concentrate was enriched from 22.8 to 32.3% Cu
whilst the Ni and Fe were reduced to 0.45 and 23.3% respectively.
The enriched copper concentrate was regarded as highly saleable due
to the +25% Cu content and reduced nickel contamination. The
precious metal grade was enriched from 2.0 to 2.84 g/t Au, 1.2 to
6.36 g/t Pt and 6.0 to 22.8 g/t Pd.
Example 3
Copper Concentrate Enrichment with a Precious Metal Free Solution
Derived from Hydrometallurgical Treatment of a Nickel-Copper
Concentrate Obtained Via Combination of a Copper Rougher Tail and a
Copper Cleaner Tail Concentrate Product
[0043] A sample of nickel-copper concentrate derived from a bulk
cleaner flowsheet with combination of copper rougher tails and
copper cleaner scavenger tails was subjected to a continuous leach
process under PLATSOL.TM. process conditions. The continuous leach
process was conducted in a 6 compartment titanium autoclave with an
average temperature of 224 C, 100 psig of oxygen, 8.5 g/L Cl, 64
minutes of average retention time with 96% recycling of autoclave
residue solids to the feed. The composition of the concentrate is
shown below.
TABLE-US-00006 TABLE 6 Nickel-Copper Flotation Concentrate Assay
Analysis (% or g/t) Cu Ni Co Fe S S.sup.2- Mg Pt Pd Au
Nickel-Copper Concentrate 5.66 3.44 0.18 34.7 24.4 23.3 1.91 3.35
10.3 0.9
[0044] The nickel-copper flotation concentrate was formed into a
slurry with water to approximately 57% solids on a weight basis.
During the continuous PLATSOL.TM. testing, the solid content was
further modified with an autoclave dilution solution of the
composition shown in Table 7. The final feed solids content was
approximately 9.5% weight. The diluted slurry was formulated to
approximate the required solid-liquid composition required to
provide autothermal operation of the PLATSOL.TM. process under
commercial autoclave conditions. Oxygen was added continuously and
in excess during the continuous PLATSOL.TM. testing with excess
oxygen removed by venting of the autoclave.
TABLE-US-00007 TABLE 7 Dilution Solution Composition for forming
the Autoclave Feed Slurry Ni Cu Fe Co Mg Au Pt Pd (g/L) (g/L) (g/L)
(g/L) (g/L) (mg/L) (mg/L) (mg/L) 20.6 0.001 0.002 0.88 4.0 <0.01
<0.01 <0.01
[0045] During the course of a 10 hour period, the discharge slurry
from the autoclave was sampled every two hours in order to observe
the progress of the PLATSOL.TM. process. The solid and liquid
analyses are shown in Tables 8 and 9 below.
TABLE-US-00008 TABLE 8 Autoclave Discharge Residue Sample Analyses
Analysis (% or g/t) Cu Ni Co Fe S.sup.2- Mg Pt Pd Au 0 h 0.06 0.40
0.01 2.33 sample 2 h 0.06 0.21 0.006 43.4 1.50 1.50 1.75 3.40 0.33
sample 4 h 0.069 0.12 0.005 40.9 1.29 1.48 0.84 1.52 0.10 sample 6
h 0.056 0.13 0.004 41.6 1.19 1.45 0.67 1.45 0.11 sample 8 h 0.059
0.12 0.004 42.0 1.22 1.64 0.42 0.77 0.09 sample 10 h 0.064 0.12
0.004 41.0 1.34 1.43 0.40 0.74 0.09 sample
TABLE-US-00009 TABLE 9 Autoclave Discharge Solution Sample Analyses
Analysis (g/L or mg/L) H.sub.2SO.sub.4 Cu Ni Co Fe Mg Pt Pd Au 0 h
43 5.09 16.1 0.72 0.46 3.00 0.07 0.32 0.04 sample 2 h 53 7.22 22.6
0.98 1.48 4.00 0.12 0.67 0.07 sample 4 h 56 7.58 23.1 1.10 1.51
4.60 0.22 0.94 0.09 sample 6 h 59 8.27 24.9 1.10 2.09 5.50 0.24
1.02 0.08 sample 8 h 59 8.26 24.3 1.10 1.51 5.50 0.33 1.26 0.09
sample 10 h 49 6.44 25.5 1.20 0.85 5.80 0.27 0.93 0.07 sample
[0046] Metal extractions through the PLATSOL.TM. Process were
calculated based on feed and residue analyses with an adjustment
for mass loss or gain. The extractions are reported in Table
10.
TABLE-US-00010 TABLE 10 PLATSOL .TM. Metal Extraction Extraction
(%) Ni Cu Fe Co Mg Au Pt Pd 97.0 99.1 -0.4 98.1 33.8 91.0 87.6
92.0
[0047] The product solution from the PLATSOL.TM. process was
recovered by filtration and washing of the solids. The solution was
then forwarded to iron reduction with sulfur dioxide gas injection
and precious metal precipitation with a precipitate of CuS.
[0048] The precious metal precipitation circuit consisted of a
preheat tank, an SO.sub.2 reduction tank (PGM1) and 2 PGM
precipitation tanks (PGM2 and PGM3). The PGM preheat tank was used
to preheat PLATSOL.TM. solution to 95.degree. C. In PGM1 ferric
iron was reduced by addition of sufficient SO2 gas to form ferrous
iron. In tank PGM2 synthetically produced CuS solids were pumped in
to maintain a target 10 g/L CuS concentration. Dissolved PGMs
precipitated onto the CuS in tanks PGM2 and PGM3 and were filtered
straight onto Buchner filters. Filtered PGM3 solids were repulped
in PGM3 filtrate and recycled to PGM2 to reduce the flow of fresh
CuS into the circuit. The target level of 10 g/L CuS was maintained
throughout, of which 90% was recycled CuS.
[0049] The analysis of combined PLATSOL.TM. solution used for this
test is summarized in Table 11 while the synthetic CuS analysis is
shown in Table 12.
TABLE-US-00011 TABLE 11 Combined PLATSOL .TM. solution for Precious
Metal Removal Analysis (g/L or mg/L) Cu Ni Co Fe Mg Pt Pd Au 7.50
23.0 1.10 1.97 4.80 0.18 0.72 0.05
TABLE-US-00012 TABLE 12 Synthetic CuS Composition Analysis (% or
g/t) Cu Ni Co Fe S.sup.2- Mg Pt Pd Au 63.2 0.004 <0.002 0.01
29.9 <0.003 <0.02 0.4 0.07
[0050] Table 13 summarizes the analysis of the product solutions
from the precious metals precipitation circuit. Table 14 shows the
analysis of the solids formed with the precipitation of precious
metals.
TABLE-US-00013 TABLE 13 Solution Samples from Precious Metal
Removal Analysis (g/L or mg/L) Sample Cu Ni Co Fe Mg Pt Pd Au
Sample 1 6.10 18.0 0.88 2.40 3.90 0.01 <0.01 <0.01 Sample 2
6.70 20.0 0.92 2.00 4.30 <0.01 <0.01 <0.01
TABLE-US-00014 TABLE 14 Solid Samples from Precious Metal Removal
Analysis (% or g/t) Sample Cu Ni Co Fe S.sup.2- Mg Pt Pd Au Sample
1 61.2 0.0 <0.002 0.10 30.9 0.01 25 4 67 Sample 2 NA NA NA NA NA
NA 28 5 85 NA--Not Analyzed
[0051] In the copper enrichment stage, copper concentrate was mixed
with PGM3 filtrate. The amount of copper concentrate added was
calculated based on the relative amounts of copper and
nickel-copper concentrates from flotation. A ratio of 0.8 copper
concentrate to 1.0 nickel-copper concentrate was established. This
ratio was further used to specify a solution volume addition per
mass of copper concentrate based on the solution volumes produced
in PLATSOL.TM. and Precious Metal removal testing. A recycle
corresponding to 0.5 to 0.7 t of enriched copper concentrate per t
of fresh copper concentrate was established to maximize the
kinetics and extent of the copper concentrate enrichment process. A
total of 3 continuous tanks with a combined retention time of 7.2 h
were used in this circuit. The copper concentrate analysis is shown
in Table 15. Table 16 and 17 show the results for copper
concentrate enrichment and copper in solution depletion. Table 16
indicates that the copper content of the solids is enriched while
the iron content in particular is decreased (compare Table 15 and
16 values). The copper in solution has decreased to as low as 0.29
g/L in the second sample (Table 17) compared with +6 g/L Cu in
Table 13 which conforms to +95% removal of copper from solution as
the copper concentrate is enriched. These results all support the
development of the copper concentrate enrichment process.
TABLE-US-00015 TABLE 15 Copper Concentrate Analysis with Precious
Metals Values Analysis (% or g/t) Cu Ni Co Fe S Au Pt Pd Copper
30.5 0.38 0.018 33.5 32.7 1.32 1.13 5.76 Concentrate
TABLE-US-00016 TABLE 16 Copper Concentrate Enrichment Test Results
for Solids Analysis (% or g/t) Cu Ni Co Fe S Au Pt Pd Sample 1 31.2
0.31 0.02 24.3 31.0 1.3 1.1 5.2 Sample 2 30.7 0.39 0.02 30.3 31.6
1.7 1.5 6.4
TABLE-US-00017 TABLE 17 Solution Analyses from Copper Concentrate
Enrichment Analysis (g/L or mg/L) Sample H.sub.2SO.sub.4 Cu Ni Co
Fe Mg Pt Pd Au Sample 1 38 1.60 17.0 0.89 8.80 4.50 <0.01
<0.01 <0.01 Sample 2 41 0.290 17.0 0.86 8.90 4.10 <0.01
<0.01 <0.01
Example 4
Copper Concentrate Enrichment with a Precious Metal Free Solution
Derived from Hydrometallurgical Treatment of a Nickel-Copper
Concentrate Corresponding to a Scavenger Concentrate Obtained from
a Split Cleaner Flowsheet
[0052] A sample of nickel-copper concentrate derived from a split
cleaner flowsheet (the scavenger concentrate) was subjected to a
continuous leach process under PLATSOL.TM. process conditions. The
continuous leach process was conducted in a 6 compartment titanium
autoclave with an average temperature of 225 C, 100 psig of oxygen,
9.6 g/L Cl, 119 minutes of average retention time with 111%
recycling of autoclave residue solids to the feed. The composition
of the concentrate is shown below.
TABLE-US-00018 TABLE 18 Nickel-Copper Flotation Concentrate Assay
Analysis (% or g/t) Cu Ni Co Fe S S.sup.2- Mg Pt Pd Au Scavenger
Concentrate 2.17 0.80 0.04 32.4 25.3 23.2 2.07 0.97 3.32 0.62
[0053] The nickel-copper flotation concentrate was formed into a
slurry with water to approximately 51% solids on a weight basis.
During the continuous PLATSOL.TM. testing, the solid content was
further modified with an autoclave dilution solution of the
composition shown in Table 19. The final feed solids content was
approximately 9.2% weight. The diluted slurry was formulated to
approximate the required solid-liquid composition required to
provide autothermal operation of the PLATSOL.TM. process under
commercial autoclave conditions. Oxygen was added continuously and
in excess during the continuous PLATSOL.TM. testing with excess
oxygen removed by venting of the autoclave.
TABLE-US-00019 TABLE 19 Dilution Solution Composition for forming
the Autoclave Feed Slurry Ni Cu Fe Co Mg Au Pt Pd (g/L) (g/L) (g/L)
(g/L) (g/L) (mg/L) (mg/L) (mg/L) 5.29 0.0003 0.003 0.210 4.0
<0.01 <0.01 <0.01
[0054] During the course of a 14 hour period, the discharge slurry
from the autoclave was sampled every two hours in order to observe
the progress of the PLATSOL.TM. process.
[0055] The solid and liquid analyses are shown in Tables 20 and 21
below.
TABLE-US-00020 TABLE 20 Autoclave Discharge Residue Sample Analyses
Analysis (% or g/t) Cu Ni Co Fe S.sup.2- Mg Pt Pd Au 0 h sample
0.063 0.12 0.004 43.8 1.32 1.41 0.38 0.67 0.10 2 h sample 0.053
0.11 0.004 43.3 1.28 1.32 0.18 0.35 0.14 4 h sample 0.037 0.083
0.003 44.8 1.23 1.19 0.11 0.21 0.13 6 h sample 0.031 0.065 0.003
44.3 1.09 1.19 0.10 0.20 0.15 8 h sample 0.027 0.055 0.002 44.9
1.02 1.19 0.09 0.21 0.15 10 h sample 0.027 0.058 0.002 45.6 0.85
1.17 0.09 0.20 0.16 12 h sample 0.028 0.051 0.002 45.7 0.80 1.18
0.07 0.20 0.14 14 h sample 0.041 0.046 0.002 46.2 0.91 1.13 0.08
0.18 0.13
TABLE-US-00021 TABLE 21 Autoclave Discharge Solution Sample
Analyses Analysis (g/L or mg/L) H.sub.2SO.sub.4 Cu Ni Co Fe Mg Pt
Pd Au 0 h sample 50 7.09 24.5 1.20 1.49 5.10 0.30 1.08 0.08 2 h
sample 56 6.66 21.5 0.94 1.43 5.30 0.28 0.96 0.06 4 h sample 59
5.30 15.6 0.71 2.81 5.60 0.25 0.89 0.06 6 h sample 63 4.88 12.8
0.56 4.74 6.20 0.23 0.81 0.06 8 h sample 73 5.11 11.5 0.50 6.66
7.10 0.20 0.72 0.07 10 h sample 70 4.81 9.45 0.43 7.24 7.00 0.17
0.62 0.06 12 h sample 71 4.74 8.59 0.40 6.91 6.90 0.16 0.60 0.07 14
h sample 67 4.45 7.74 0.36 5.52 6.40 0.17 0.64 0.08
[0056] Metal extractions through the PLATSOL.TM. Process were
calculated based on feed and residue analyses with an adjustment
for mass loss or gain. The extractions are reported in Table
22.
TABLE-US-00022 TABLE 22 PLATSOL .TM. Metal Extraction Extraction
(%) Ni Cu Fe Co Mg Au Pt Pd 95.5 99.0 3.7 96.7 61.4 84.0 94.2
95.9
[0057] The product solution from the PLATSOL.TM. process was
recovered by filtration and washing of the solids. The solution was
then forwarded to iron reduction with sulfur dioxide gas injection
and precious metal precipitation with a precipitate of CuS.
[0058] The precious metal precipitation circuit consisted of a
preheat tank, an SO.sub.2 reduction tank (PGM1) and 2 PGM
precipitation tanks (PGM2 and PGM3).
[0059] The PGM preheat tank was used to preheat PLATSOL.TM.
solution to 95.degree. C. In PGM1 ferric iron was reduced by
addition of sufficient SO2 gas to form ferrous iron. In tank PGM2
synthetically produced CuS solids were pumped in to maintain a
target 10 g/L CuS concentration. Dissolved PGMs precipitated onto
the CuS in tanks PGM2 and PGM3 and were filtered straight onto
Buchner filters. Filtered PGM3 solids were repulped in PGM3
filtrate and recycled to PGM2 to reduce the flow of fresh CuS into
the circuit. The target level of 10 g/L CuS was maintained
throughout, of which .about.90% was recycled CuS.
[0060] The analysis of combined PLATSOL.TM. solution used for this
test is summarized in Table 23 while the synthetic CuS analysis is
shown in Table 24.
TABLE-US-00023 TABLE 23 Combined PLATSOL .TM. solution for Precious
Metal Removal Analysis (g/L or mg/L) Cu Ni Co Fe Mg Pt Pd Au 4.80
11.0 0.54 5.50 6.60 0.20 0.63 0.04
TABLE-US-00024 TABLE 24 Synthetic CuS Composition Analysis (% or
g/t) Cu Ni Co Fe S.sup.2- Mg Pt Pd Au 63.2 0.004 <0.002 0.01
29.9 <0.003 <0.02 0.4 0.07
[0061] Table 25 summarizes the analysis of the product solutions
from the precious metals precipitation circuit. Table 26 shows the
analysis of the solids formed with the precipitation of precious
metals.
TABLE-US-00025 TABLE 25 Solution Samples from Precious Metal
Removal Analysis (g/L or mg/L) Sample Cu Ni Co Fe Mg Pt Pd Au
Sample 1 6.50 18.0 0.84 3.10 5.40 <0.01 0.01 <0.01 Sample 2
5.30 13.0 0.58 4.90 6.10 <0.01 <0.01 <0.01 Sample 3 4.80
12.0 0.55 5.30 6.40 0.01 0.01 0.01
TABLE-US-00026 TABLE 26 Solid Samples from Precious Metal Removal
Analysis (% or g/t) Sample Cu Ni Co Fe S.sup.2- Mg Pt Pd Au Sample
1 42.7 0.10 0.004 0.20 20.3 0.02 66 170 11 Sample 2 59.6 0.0
<0.002 0.60 28.1 0.01 90 244 16
[0062] In the copper enrichment stage, copper concentrate was mixed
with PGM3 filtrate. The amount of copper concentrate added was
calculated based on the relative amounts of copper and
nickel-copper concentrates from flotation. A ratio of 1.0 copper
concentrate to 1.0 nickel-copper concentrate was established. This
ratio was further used to specify a solution volume addition per
mass of copper concentrate based on the solution volumes produced
in PLATSOL.TM. and Precious Metal removal testing. A recycle
corresponding to 0.5 to 0.7 t of enriched copper concentrate per t
of fresh copper concentrate was established to maximize the
kinetics and extent of the copper concentrate enrichment process. A
total of 3 continuous tanks with a combined retention time of 7.2 h
were used in this circuit. The copper concentrate analysis is shown
in Table 27. Table 28 and 29 show the results for copper
concentrate enrichment and copper in solution depletion. Table 28
indicates that the copper content of the solids is enriched while
the iron content in particular is decreased (compare Table 27 and
28 values). The copper in solution has decreased to as low as 0.24
g/L in the second sample (Table 29) compared with +4.8 g/L Cu in
Table 25 which conforms to +95% removal of copper from solution as
the copper concentrate is enriched. These results all support the
development of the copper concentrate enrichment process.
TABLE-US-00027 TABLE 27 Copper Concentrate Analysis with Precious
Metals Values Analysis (% or g/t) Cu Ni Co Fe S Au Pt Pd Copper
30.5 0.64 0.025 31.5 31.1 1.60 1.44 9.24 Concentrate
TABLE-US-00028 TABLE 28 Copper Concentrate Enrichment Test Results
for Solids Analysis (% or g/t) Cu Ni Co Fe S Au Pt Pd Sample 1 30.7
0.39 0.02 30.3 31.6 1.70 1.50 6.40 Sample 2 30.5 0.52 0.02 28.5 32
1.60 1.30 7.70 Sample 3 29.7 0.55 0.03 29.4 32.7 1.60 1.30 8.5
TABLE-US-00029 TABLE 29 Solution Analyses from Copper Concentrate
Enrichment Analysis (g/L or mg/L) Sample H.sub.2SO.sub.4 Cu Ni Co
Fe Mg Pt Pd Au Sample 1 41 0.29 17.0 0.86 8.90 4.10 <0.01
<0.01 <0.01 Sample 2 50 0.24 15.0 0.67 9.30 4.90 <0.01
<0.01 <0.01 Sample 3 50 0.25 11.0 0.48 9.80 5.80 <0.01
<0.01 <0.01
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* * * * *