111111111111111111111111111111111111111111111111111111111111111111111111111
US008003064B2
(12) United States Patent
Savage et al.
(10) Patent No.:
(45) Date of Patent:
US 8,003,064 B2
Aug. 23, 2011
( *) Notice:
(54) CONTROLLED COPPER LEACH RECOVERY
CIRCUIT
(75) Inventors: Barbara J. Savage, Silver City, NM
(US); David G. Meadows, Phoenix, AZ
(US); Wayne W. Hazen, Lakewood, CO
(US)
(73) Assignee: Freeport-McMoran Corporation,
Phoenix, AZ (US)
Subject to any disclaimer, the term ofthis
patent is extended or adjusted under 35
U.S.c. 154(b) by 936 days.
(21) Appl. No.: 11/856,605
6,107,523 A
6,177,055 Bl
6,242,625 Bl
6,350,354 Bl
6,395,062 B2
6,432,167 Bl
6,596,053 B2
6,599,414 Bl
6,702,872 Bl
6,726,887 Bl
6,733,688 Bl
7,166,144 B2
7,169,371 B2
7,214,256 B2
7,309,474 B2
7,390,468 B2
2005/0031512 Al
2006/0088458 Al
2006/0117908 Al
8/2000 Virnig et al.
112001 Virnig et al.
6/2001 Kordosky
2/2002 Neuman et al.
5/2002 Olafson et al.
8/2002 Virnig et al.
7/2003 Virnig et al.
7/2003 Virnig et al.
3/2004 Virnig et al.
4/2004 Sugarman
5/2004 Sugarman et al.
112007 Hein et al.
112007 Jones
5/2007 Kordosky et al.
12/2007 Soderstrom
6/2008 Pekkala et al.
2/2005 Kordosky et al.
4/2006 Kordosky et al.
6/2006 Virnig et al.
US 2009/0074639 Al
(22) Filed:
(65)
Sep. 17, 2007
Prior Publication Data
Mar. 19,2009
WO
WO
FOREIGN PATENT DOCUMENTS
W00015857 3/2000
WO 2006/041695 4/2006
OTHER PUBLICATIONS
Primary Examiner - Steven Bos
(74) Attorney, Agent, or Firm - Snell & Wilmer L.L.P.
International Search Report and Written Opinion from corresponding
PCT Application No. PCTIUS2008/075037 dated Dec. 10,2008.
International Preliminary Report on Patentability for corresponding
Int'I Application No. PCTIUS08/075037 dated Apr. 1,2010.
(51) Int. Cl.
C21B 15/00 (2006.01)
(52) U.S. Cl. 423/24; 205/560; 205/568; 205/580;
205/589; 205/604; 75/722
(58) Field of Classification Search 423/24;
205/560,568,580, 589, 604; 75/722
See application file for complete search history.
(57) ABSTRACT
(56) References Cited
U.S. PATENT DOCUMENTS
1,841,437 A 111932 Greenawalt
4,582,689 A 4/1986 Kordosky
4,666,512 A 5/1987 Hansen et al.
4,957,714 A 9/1990 Olafson et al.
5,470,552 A 1111995 Kordosky et al.
5,632,963 A 5/1997 Schwab et aI.
5,908,605 A 6/1999 Virnig et aI.
5,919,674 A 7/1999 Tunley
5,976,218 A 1111999 Virnig et aI.
The present invention relates generally to a process for controlled
leaching and sequential recovery oftwo or more metals
from metal-bearing materials. In one exemplary embodiment,
recovery of metals from a leached metal-bearing
material is controlled and improved by providing a high grade
pregnant leach solution ("HGPLS") and a low grade pregnant
leach solution ("LGPLS") to a single solution extraction plant
comprising at least two solution extractor units, at least two
stripping units, and, optionally, at least one wash stage.
25 Claims, 4 Drawing Sheets
u.s. Patent Aug. 23, 2011 Sheet 1 of 4
100
US 8,003,064 B2
PREPARATION OF METAL 250
BEARING MATERIAL
REACTIVE PROCESSING STEP
CONDITIONING STEP
202
203
104 ~105
SOLUTION EXTRACTION STEP 252
PRIMARY METAL RECOVERY
106 107
SECONDARY METAL RECOVERY
207
FIG. 1
u.s. Patent Aug. 23, 2011 Sheet 2 of 4 US 8,003,064 B2
305
304
SOLUTION EXTRACTION PLANT
300
100
CONTROLLED GRINDING
(OPTIONAL)
101 302
LEACHING
102
FLASHING (OPTIONAL)
103
200
285
202
3031---------"---~f_---.L!~
204
307
ADDITIONAL EXEMPLARY
LEACHING PROCESSES
FIG.2A
276
205
ELECTROLYTE RECYCLE TANK
108
253
ELECTROWINNING
208
Cu
FIG. 28
402
~
7Jl
•
~
~
~
~=~
104
High grade
Pregnant Leach I )
Solution . I HIGH GRADE SOLUTION I ) •
FIG. 3
rFJ =('
D
(..'D...
(.H
o....
,j;o,.
~
~
N
(.H
~
No
........
d
rJl
QO -==w -=0'1
~=N
401
210
--.2. 277
1-----·------------, )
STRIPPING UNIT (OPTIONAL): Rich •
I I
L. - - - - - - - - - - - - - - - - - - - Electrolyte
400
306
306
105 305
Wash water
Lean
Electrolyte
Low grade
Pregnant Leach I )~
Solution . I LOW GRADE SOLUTION I. •
EXTRACTION UNIT
STRIPPING UNIT
Rich
Electrolyte
212
r------------------~,
I .1 ORGANIC WASH (OPTIONAL) : •
~ - - - - - - - - - - - - - - - - - - - I Reject Water
High grade
Pregnant Leach
Solution
High grade
raffinate
Low grade
Pregnant Leach
Solution
Low grade
raffinate
Lean
Electrolyte
Rich
Electrolyte
~
7J).
•
~
~
~
~=~
V 104 --./304 --./105 --../282 V 306 --./277
......,...209 Additional ......,...213 V 211 Additional '-./214 '-./210 V210
High Grade Serial Low Grade Serial
Solution Solution Solution Solution Stripping Unit Stripping Unit
~
Extractor Unit Extractor Unit ~ Extractor Unit ~O Extractor Unit (High Grade) (Low Grade) ~1
402
~ Loaded Organic
FIG. 4
~
~
N
(.H
~
No
........
rFJ =('
D
(..'D...
,j;o,.
o....
,j;o,.
d
rJl
QO -==w -=0'1
~=N
US 8,003,064 B2
2
SUMMARY OF THE INVENTION
However, under these current leaching and solution extraction
processes, large concentrations of soluble metal and
metal precipitate can be lost in the metal-depleted, acidcontaining
aqueous phase raffinate solutions. These losses
lead to inefficiencies and low overall process yields. Additionally,
these high metal concentrations in the raffinate make
recovery ofsecondary metals costly and possibly impractical.
Accordingly, a process circuit for controlling the concentration
of metal, especially copper, in the raffinate solution
10 which is the feed for the subsequent recovery of secondary
metals without negatively affecting the primary metal recovery
circuit would be advantageous.
FIELD OF INVENTION
1
CONTROLLED COPPER LEACH RECOVERY
CIRCUIT
The present invention relates generally to a process for
controlled leaching and sequential recovery of two or more
metals from metal-bearing materials. In one exemplary
embodiment, recovery of metals from a leached metal-bearing
material is controlled and improved by providing a high
grade pregnant leach solution ("HGPLS") and a low grade
pregnant leach solution ("LGPLS") to a single solution
extraction plant comprising at least two solution extractor
units, at least two stripping units, and, optionally, at least one 15
wash stage.
BRIEF DESCRIPTION OF THE DRAWING
A more complete understanding of the present invention,
however, may best be obtained by referring to the detailed
description when considered in counection with the drawing
figures, wherein like numerals denote like elements and
wherein:
FIG. 1 illustrates a flow diagram of a general metal recovery
process in accordance with the present invention;
FIG. 2A illustrates a flow diagram of an alternate preparation
process in accordance with the present invention;
FIG. 2B illustrates a flow diagram of an exemplary
embodiment of a metal recovery process in accordance with
the present invention;
FIG. 3 illustrates a solution extraction process in accordance
with the present invention; and
The present invention relates generally to a process for
controlled leaching and sequential recovery of two or more
metals from metal-bearing materials. In one exemplary
20 embodiment, recovery of metals from a leached metal-bearing
material is controlled and improved by providing a high
grade pregnant leach solution ("HGPLS") and a low grade
pregnant leach solution ("LGPLS") to a single solution
extraction plant comprising at least two solution extractor
25 units, at least two stripping units, and, optionally, at least one
wash stage.
For example, in accordance with the various exemplary
embodiments of the present invention, the present process
comprises (a) providing a HGPLS to a solution extractor unit
30 within a single solution extraction plant, (b) producing a high
grade raffinate and a metal-loaded organic solution by contacting
the HGPLS with a partially loaded organic solution in
the solution extractor, (c) providing a LGPLS to a different
solution extractor unit within the same solution extraction
35 plant, and (d) producing a low grade raffinate and the partially
loaded organic solution by contacting the LGPLS with a
barren organic flow containing a metal-specific extraction
reagent. Furthermore, in accordance with the various
embodiments of the present invention, the flow rate and
40 reagent concentration ofthe barren organic flow containing a
metal-specific extraction reagent can be altered based on the
incoming metal material quality to maintain a constant concentration
of metal in the low grade raffinate, allowing for
efficient secondary metal recovery, including but not limited
45 to cobalt recovery. In accordance with an exemplary embodiment
of the present invention, the concentration of metal in
the LGPLS may be adjusted by blending a portion of the
LGPLS with the high grade pregnant leach solution so that the
quantity of metal entering the low grade extraction circuit
50 remains substantially constant.
BACKGROUND OF THE INVENTION
Hydrometallurgical treatment of metal-bearing materials,
such as metal ores, metal-bearing concentrates, and other
metal-bearing substances, has been well established for many
years. Moreover, leaching of metal-bearing materials is a
fundamental process utilized to extract metals from metalbearing
materials. In general, the first step in this process is
contacting the metal-bearing material with an aqueous solution
containing a leaching agent or agents which extracts the
metal or metals from the metal-bearing material into solution.
For example, in copper leaching operations, especially copper
from copper minerals, such as chalcopyrite, chalcocite,
covellite, malachite, pseudomalachite, azurite, chrysocolla,
and cuprite, sulfuric acid in an aqueous solution is contacted
with copper-bearing ore. During the leaching process, acid in
the leach solution may be consumed and various soluble
components are dissolved thereby increasing the metal content
of the aqueous solution. Other ions, such as iron may
participate in the leaching of various minerals as these ions
participate in dissolution reactions.
The aqueous leach solution containing the leached metal
can then be treated via a known process referred to as solution
extraction wherein the aqueous leach solution is contacted
with an organic solution comprising a metal-specific extraction
reagent, for example, an aldoxime and/or ketoxime or a
mixture thereof. The metal-specific extraction reagent
extracts the metal from the aqueous phase into the organic
phase. Moreover, during the solution extraction process for
copper and certain other metals, a leaching agent may be
regenerated in the aqueous phase. In the case where sulfuric
acid is the leaching agent, sulfuric acid is regenerated in the
aqueous phase when copper is extracted into the organic
phase by the extraction reagent. Iron ions, which should not
be extracted by the metal-specific extraction reagent, should
be recycled to the leaching step to the maximum extent possible.
In a standard agitation leaching process for copper, fol- 55
lowed by solution extraction, the leach solution is diluted to a
lesser or greater extent with acidified water in conjunction
with the solid-liquid separation process needed to provide a
clarified leach liquor and solid discharge. The diluted clarified
leach solution then undergoes solution extraction 60
wherein copper is removed from, and the sulfuric acid concentration
is increased in, the aqueous phase.A portion ofthis
copper-depleted, acid-containing aqueous phase, now called
the raffinate, may be recycled back to the leaching process,
recycled to the front of the solid-liquid separation process, 65
and/or forwarded to secondary metal extraction processes,
including but not limited to cobalt recovery.
US 8,003,064 B2
3 4
mation, as well as chemical and/or physical conditioning in
preparation step 250 before metal extraction.
Referring again to FIG. 1, in an exemplary embodiment of
the present invention, after metal-bearing material 100 has
been suitably prepared in preparation step 250 for metal
recovery processing, it may be forwarded to a reactive processing
step 202, for example, metal extraction. The reactive
processing step 202 may be any suitable process or reaction
that puts a metal in the metal-bearing material 100 in a con-
10 dition such that it may be subjected to later metal recovery
processing. For example, exemplary suitable processes
include reactive processes that tend to liberate the desired
metal value or values in the metal bearing material 100 from
the metal-bearing material 100. In accordance with a pre-
IS ferred embodiment of the present invention, as described in
greater detail below, reactive processing step 202 may comprise
a leaching process.
In one aspect of an exemplary embodiment of the present
invention, conditioning ofa metal-bearing solution after reac-
20 tive process step 202 begins by adjusting certain physical
parameters in conditioning step 203. For example, as discussed
in some detail herein below, after reactive processing
202 metal-bearing material 100 may undergo reagent additions,
flashing processes, one ormore solid-liquid phase sepa-
25 ration steps including use of filtration systems, counter-current
decantation (CCD) circuits, thickeners, clarifiers, or any
other suitable device for solid-liquid separation, in conditioning
step 203 to prepare the metal solubilized therein for recovery.
Further, referring again to FIG. 1, in an exemplary embodiment
of the present invention, after metal-bearing material
100 has been suitably conditioned in conditioning step(s) 203
it may be forwarded to solution extraction step 252. In accordance
with further aspects ofthis exemplary embodiment, the
35 conditioning step(s) 203 produces a high grade pregnant
leach solution ("HGPLS") 104, comprising high concentrations
of dissolved metal values, and a low grade pregnant
leach solution ("LGPLS") 105, comprising a lower concentration
of dissolved metal values than found in the HGPLS
40 104. In another exemplary embodiment, as discussed in some
detail herein below, the HGPLS 104 and LGPLS 105 may be
produced by separate reactive processing steps and/or separate
conditioning steps.
Regardless ofthe reactive step which produces the HGPLS
45 104 and LGPLS 105, in an exemplary embodiment of the
present invention, at least one HGPLS 104 stream and at least
one LGPLS 105 stream is forwarded to solution extraction
step 252. In accordance with an exemplary embodiment of
the present invention, solution extraction step 204 comprises
50 only one solution extraction plant. For example, in accordance
with an exemplary embodiment of the present invention,
solution extraction plant 204 may comprise multiple
interconnected solution extraction trains within a single solution
extraction plant 204. Generally, in accordance with the
55 various embodiments of the present invention, the single
solution extraction plant 204 is housed in one facility. It
should be understood that this disclosure teaches, inter alia,
efficient and controllable metal solution extraction from more
than two separate pregnant leach solution ("PLS") feed
60 streams containing two or more recoverable metal values in a
single solution extraction plant and that any number of PLS
streams are contemplated herein.
In contrast, the prior art teaches only multiple plant solution
extraction for more than one PLS feed stream. It should
65 be understood that any multiple plant solution extraction
design requires roughly twice the equipment and capital cost
in reference to a single solution extraction plant.
DETAILED DESCRIPTION OF EXEMPLARY
EMBODIMENTS
FIG. 4 illustrates one solution extraction plant for processing
multiple leach solution streams in accordance with an
exemplary embodiment of the present invention.
The detailed description ofexemplary embodiments ofthe
invention herein shows various exemplary embodiments and
the best modes, known to the inventors at this time. These
exemplary embodiments and modes are described in sufficient
detail to enable those skilled in the art to practice the
invention and are not intended to limit the scope, applicability,
or configuration of the invention in any way. Rather, the
following disclosure is intended to teach both the implementation
of the exemplary embodiments and modes and any
equivalent modes or embodiments that are known or obvious
to those of reasonable skill in the art. Additionally, all
included figures are non-limiting illustrations of the exemplary
embodiments and modes, which similarly avail themselves
to any equivalent modes or embodiments that are
known or obvious to those of reasonable skill in the art.
Various embodiments ofthe present invention exhibit significant
advancements over prior art processes, particularly
with regard to metal recovery and process efficiency. Moreover,
existing copper recovery processes that utilize a reactive
process for metal recovery/solution extraction/electrowinning
process sequence may, in many instances, be easily
retrofitted to exploit the many commercial benefits the 30
present invention provides.
Referring to FIG. 1, in accordance with various aspects of
the present invention, a metal-bearing material 100 is provided
for processing. Metal-bearing material 100 may be an
ore, a concentrate, or any other material from which copper
and/or other metal values may be recovered. Metal values
such as, for example, copper, gold, silver, zinc, platinum
group metals, nickel, cobalt, molybdenum, rhenium, uranium,
rare earth metals, and the like, may be recovered from
metal-bearing materials in accordance with various embodiments
of the present invention. The various aspects and
embodiments of the present invention, however, prove especially
advantageous in connection with the recovery of copper
from copper-bearing materials, such as, for example, ores
and/or concentrates containing chalcopyrite (CuFeS2), chalcocite
(Cu2S), bornite (CusFeS4), and covellite (CuS), malachite
(CU2C03 (OH)2)' pseudomalachite (CuS[(OH)2P04]2)'
azurite (CU3(C03MOH)2), chrysocolla ((Cu,Al)2H2Si20s
(OH)4.nH20), cuprite (Cu20), brochanite (CuS04.3Cu
(OH)2), atacamite (Cu2[OH3 Cl]) and other copper-bearing
minerals or materials and mixtures thereof. Thus, metal-bearing
material 100 preferably is a copper ore or concentrate
containing at least one other metal value.
Metal-bearing material 100 may be prepared in preparation
step 250 for metal recovery processing in any manner that
enables the conditions ofmetal-bearing material 100 -such
as, for example, composition and component concentration
-to be suitable for the chosen reactive processing method, as
such conditions may affect the overall effectiveness and efficiency
of metal recovery operations. Desired composition
and component concentration parameters can be achieved
through a variety of chemical and/or physical processing
stages, the choice of which will depend upon the operating
parameters ofthe chosen processing scheme, equipment cost
and material specifications. For example, as discussed in
some detail herein below, metal-bearing material 100 may
undergo combination, flotation, blending, and/or slurry forUS
8,003,064 B2
5 6
(2)
(1)
4CuFeS2+1702+4H20~2Fe203+4Cu2++8H++
8soi-
Thus, in accordance with one aspect of the present invention,
in order to maintain preferable leaching temperature, a
cooling liquid 301 may be introduced into the leaching vessel
At lower temperatures, acid is generally consumed and
elemental sulfur is fonned according to the following reaction:
plated herein and the subject matter of that patent is hereby
incorporated by reference. Preferably, a uniform particle size
distribution is achieved. Additionally, process water 300 is
preferably added to metal-bearing material stream 100 to
bring the percent solids to the optimal pulp density specified
for the controlled grinding unit 200. It should be understood
that a variety ofacceptable techniques and devices for reducing
the particle size of the copper-bearing material are currently
available, such as ball mills, tower mills, grinding
10 mills, attrition mills, stirred mills, horizontal mills and the
like, and additional techniques may later be developed that
may achieve the desired result ofreducing the particle size of
the copper-bearing material to be transported.
Referring again to both FIG. 1 and FIG. 2B, in an exem-
15 plary embodiment ofthe present invention, after metal-bearing
material 100 has been suitably prepared for metal recovery
processing, optionally by controlled grinding 200, and
other physical and/or chemical conditioning processes,
including but not limited to a thickening process, it may be
20 combined with any number ofliquid feed stream, represented
by numerical reference 307, to fonn a metal-bearing inlet
stream 101. Preferably, in an exemplary embodiment of the
present invention, the liquid feed stream 307 comprises process
water, but any suitable liquid may be employed, such as,
25 for example, recycled raffinate, pregnant leach solution, lean
electrolyte, and/or other recycled streams from the metal
recovery processes, including but not limited to secondary
metal, such as cobalt or iron, recovery process streams.
Further, in an exemplary embodiment ofthe present inven-
30 tion, metal-bearing inlet stream 101 is subjected to a reactive
processing step 202 (FIG. 1), for example, metal extraction.
The reactive processing step 202 (FIG. 1) may be any suitable
process or reaction that puts a metal in metal-bearing material
100 in a condition such that it may be subjected to later metal
35 recovery processing. In accordance with one embodiment of
the present invention, reactive processing step 202 (FIG. 1)
comprises a leaching step 201 (FIG. 2B). Furthennore, in an
exemplary embodiment ofthe present invention, the leaching
process may comprise any leaching process suitable for
40 extracting the metal in metal-bearing material 100 into an
aqueous leach solution 102. In accordance with one aspect of
the present invention, the leach step 201 comprises atmospheric
leaching, pressure leaching, whole ore leaching, agitation
leaching, heap leaching, stockpile leaching, pad leach-
45 ing, thin-layer leaching and/or vat leaching, at either ambient
or elevated temperatures. Preferably, pressure leaching 201 is
a pressure leaching process operating at a temperature in the
range of about 1400 C. to about 2500 C. and more preferably
in the range of about 1500 C. to about 2200 C.
In accordance with an aspect of the present invention, the
optimum temperature range selected for operation will tend
to maximize the extraction of copper and other metals, minimize
acid consumption, and thereby minimize make-up acid
requirements. That is, at higher temperatures, sulfide sulfur
55 generally is converted to sulfate according to the following
reaction:
Moreover, in accordance with an exemplary embodiment
of the present invention, single solution extraction plant 204
comprises at least two solution extractor units, at least two
stripping units, and, optionally, at least one wash stage, which
are housed in the same facility. It should be understood that
this disclosure teaches, inter alia, any number of solution
extractor units, any number ofstripping units, and, optionally,
any number ofwash stages for processing any number ofPLS
streams are contemplated herein.
Generally, as will be described in greater detail below, in
accordance with an exemplary embodiment of the present
invention, LGPLS 105 is subjected to a solution extractor
unit, wherein a barren organic flow containing a metal-specific
extraction reagent extracts at least one metal value from
the LGPLS 105 into the organic phase to fonn a partially
loaded organic solution and a low grade raffinate 107. Additionally,
in accordance with an exemplary embodiment ofthe
present invention, HGPLS 104 is subjected to a different
solution extractor unit within the same solution extraction
plant 204, wherein the partially loaded organic solution further
extracts at least one metal value from the HGPLS 104
into the organic phase to form a metal-loaded organic solution,
rich electrolyte, 106, preferably containing a high concentration
ofprimary metal values, and a high grade raffinate.
Further, referring again to FIG. 1, in an exemplary embodiment
of the present invention, after solution extraction step
252, the resulting metal-loaded solution 106 may be forwarded
to primary metal recovery, illustrated as step 206. In
accordance with various aspects ofthe present invention primary
metal recovery step 206 may be any metal recovery
process, for example, electrowinning, sulphidation, precipitation,
ion exchange or any other process suitable for recovery
of metals, may be utilized. In an exemplary embodiment of
the present invention metals to be recovered in primary metal
recovery step 206 may include copper, silver, platinum group
metals, molybdenum, zinc, nickel, cobalt, uranium, rhenium,
rare earth metals, and the like. In a preferred exemplary
embodiment of the present invention, primary recovery step
preferably comprises an electrowinning circuit suitably
designed to carry out any electrowinning process capable of
producing a metal cathode product 208.
Similarly, referring again to FIG. 1, in an exemplary
embodiment ofthe present invention, after solution extraction
step 252, the resulting low grade raffinate 107 may be forwarded
to one or more secondary metal recovery steps 207. In
an exemplary embodiment of the present invention, additional
electrowinning circuits may be employed in the secondary
metal recovery step 207. Moreover, in an exemplary
embodiment of the present invention, the secondary metal
recovery step 207 may comprise any metal recovery process, 50
for example, electrowinning, sulphidation, precipitation, ion
exchange, cyanidation, or any other process suitable for
recovery of secondary metals. Preferably, as discussed in
some detail herein below, in an exemplary embodiment ofthe
present invention, precipitation processes are used, thus making
it advantageous to have low concentrations of primary
metals in the low grade raffinate. Additionally, in an exemplary
embodiment ofthe present invention, secondary metals
to be recovered in secondary metal recovery step 207 may
include, silver, platinum group metals, molybdenum, zinc, 60
nickel, cobalt, uranium, rhenium, rare earth metals, and the
like.
Now with reference to FIG. 1 and FIG. 2B, in accordance
with one aspect ofthe present invention, metal-bearing material
100 may optionally be prepared in a preparation step 250 65
comprising controlled grinding 200. More precisely, U.S. Pat.
No. 6,676,909 describing controlled grinding is contemUS
8,003,064 B2
7 8
concentrations, solids content, volume, temperature, pressure,
and/or other physical and/or chemical parameters to
desired values and thus to form a suitable metal-bearing solution.
Generally, a properly conditioned metal-bearing solution
will contain a relatively high concentration of soluble
metal, for example, copper sulfate, in an acid solution and
preferably will contain few impurities. Moreover, the conditions
of the metal-bearing solution preferably are kept substantially
constant to enhance the quality and uniformity of
the copper product ultimately recovered. conditioning steps
203 (FIG. 1). In one exemplary embodiment, the product
stream 102 from leaching step 201 may be conditioned to
adjust the composition, component concentrations, solids
content, volume, temperature, pressure, and/or other physical
and/or chemical parameters to desired values and thus to form
a suitable metal-bearing solution. Generally, a properly conditioned
metal-bearing solution will contain a relatively high
concentration of soluble metal, for example, copper sulfate,
in an acid solution and preferably will contain few impurities.
20 Moreover, the conditions of the metal-bearing solution preferably
are kept substantially constant to enhance the quality
and uniformity of the copper product ultimately recovered.
In one aspect of an exemplary embodiment of the present
invention, conditioning of a metal-bearing solution for metal
recovery begins by adjusting certain physical parameters of
the product slurry 102 from the leaching step 201. Optionally,
in an exemplary aspect of this embodiment of the invention,
wherein the leaching step 201 is pressure leaching, it is desirable
to reduce the temperature and pressure of the product
slurry, in some instances to approximately ambient conditions.
An exemplary method of so adjusting the temperature
and pressure characteristics of the product slurry is flashing
251 (FIG. 2B). In one aspect ofan exemplary embodiment of
the present invention, flashing step 251 (FIG. 2B) comprises
atmospheric flashing. Further, flashed gases, solids, solutions,
and steam may optionally be suitably treated, for
example, by use of a Venturi scrubber wherein water may be
recovered and hazardous materials may be prevented from
entering the environment.
In accordance with further aspects of this exemplary
embodiment, either the slurry product 102 directly from the
leach process 201 or the flashed product slurry 103, if subjected
to a flashing step 202 (FIG. 2B), may be further conditioned
in preparation for later metal-value recovery steps.
For example, one or more solid-liquid phase separation steps
285 (FIG. 2B) may be used to separate solubilized metal
solution from solid particles. This may be accomplished in
any conventional manner, including use of filtration systems,
counter-current decantation (CCD) circuits, thickeners, clarifiers,
and the like. A variety of factors, such as the process
material balance, environmental regulations, residue composition,
economic considerations, and the like, may affect the
decision whether to employ a CCD circuit, a thickener, a
filter, a clarifier, or any other suitable device in a solid-liquid
separation apparatus. In one aspect ofan exemplary embodiment
of the invention, one or more solid-liquid phase separation
steps 285 (FIG. 2B) may be carried out with a conventional
CCD utilizing conventional countercurrent washing of
the residue stream to recover leached metal values to one or
more solution products and to minimize the amount of
soluble metal values advancing with the solid residue to further
metal recovery processes or storage.
In accordance with further aspects of this exemplary
embodiment, as exemplified in FIG. 2B, the solid-liquid
phase separation step 285 produces a high grade pregnant
leach solution ("HGPLS") 104, comprising high concentrations
of dissolved metal values, and a low grade pregnant
201 during leaching. In accordance with one aspect of this
embodiment ofthe present invention, a cooling liquid 301 is
preferably contacted with the feed stream in leaching vessel
201 during leaching. Cooling liquid 301 may comprise makeup
water, but can be any suitable cooling fluid from within the
process or from an outside source, such as recycled liquid
phase from the product slurry or a mixture of cooling fluids.
Cooling liquid may be introduced into leaching vessel 201
through the same inlet as metal-bearing inlet stream 101, or in
any manner that effectuates cooling of metal-bearing inlet 10
stream 101. The amount ofcooling liquid added during leaching
may vary according to the pulp density of the metalbearing
inlet stream 101, as well as other parameters of the
leaching process. In an exemplary aspect ofthis embodiment
of the invention, a sufficient amount of cooling liquid 301 is 15
added to leaching vessel 201 to yield a solids content in
product slurry 102 on the order ofless than about 50% solids
by weight, more preferably ranging from about 3 to about
35% solids by weight, and most preferably ranging from
about 10% to about 20% solids by weight.
Moreover, in accordance with one aspect of the present
invention, leaching step 201 may occur in any pressure leaching
vessel suitably designed to contain the pressure leaching
mixture at the desired temperature and pressure conditions
for the requisite pressure leaching residence time. In accor- 25
dance with one aspect of an exemplary embodiment of the
invention, the pressure leaching vessel used in leaching step
201 is an agitated, multi-compartment pressure leaching vessel.
However, it should be appreciated that any pressure leaching
vessel that suitably permits metal-bearing material 100 to 30
be prepared for metal recovery may be utilized within the
scope of the present invention.
During leaching step 201, copper and/or other metal values
may be solubilized or otherwise liberated in preparation for
later recovery processes. Any substance that assists in solu- 35
bilizing the metal value, and thus releasing the metal value
from a metal-bearing material, may be used. For example,
where copper is the metal being recovered, an acid, such as
sulfuric acid, may be contacted with the copper-bearing material
such that the copper may be solubilized for later recovery 40
steps. However, it should be appreciated that any suitable
method of solubilizing metal values in preparation for later
metal recovery steps may be utilized within the scope ofthis
invention.
In accordance with one aspect of the present invention, 45
during pressure leaching in leaching vessel 201, sufficient
oxygen 302 is injected into the vessel to maintain an oxygen
partial pressure from about 50 to about 200 psi, preferably
from about 75 to about 750 psi and most preferably from
about 100 to about 400 psi Furthermore, due to the nature of 50
medium temperature pressure leaching, the total operating
pressure in leaching vessel 201 is generally superatmospheric.
The residence time for the pressure leaching process can
vary, depending on factors such as, for example, the charac- 55
teristics of the copper-bearing material and the operating
pressure and temperature of the pressure leaching vessel. In
one aspect ofan exemplary embodiment ofthe invention, the
residence time for the pressure leaching ranges from about 30
to about 180 minutes, more preferably from about 60 to about 60
120 minutes.
Subsequent to metal-bearing material 100 undergoing
leaching step 201, the metal values that have been made
available by the leaching process undergo one or more of
various conditioning steps 203 (FIG. 1). In one exemplary 65
embodiment, the product stream 102 from leaching step 201
may be conditioned to adjust the composition, component
US 8,003,064 B2
9
leach solution ("LGPLS") 105, comprising a lower concentration
of dissolved metal values than found in the HGPLS
104. Preferably, in accordance with further aspects of this
exemplary embodiment, large wash ratios are utilized in the
solid-liquid phase separation steps 285-that is, relatively
large amounts of wash water are added to either the slurry
product 102 or, if after the product slurry has been subjected
to a flashing step 202, the flashed product slurry 103. This
wash water collects the remaining dissolved metal values and
thus becomes the LGPLS 105.
As further discussed herein below, the separated solids
may further be subjected to later processing steps, including
other metal recovery, such as, for example, recovery of gold,
silver, platinum group metals, molybdenum, zinc, nickel,
cobalt, uranium, rhenium, rare earth metals, and the like, by
sulphidation, cyanidation, or other techniques. Alternatively,
the separated solids may be subject to impoundment or disposal.
The liquid separated from a solid-liquid phase separation
step 285 may also undergo a series of conditioning steps to
prepare the metal solubilized therein for recovery. For
example, the separated liquid may undergo various reagent
additions to put the metal in a state such that the metal is
susceptible to conventional metal recovery techniques. Further,
subsequent conditioning and/or processing steps may be
undertaken such that recovery rates are as efficient as possible.
Referring to FIG. 1 and FIG. 2B, in accordance with an
exemplary embodiment of the present invention, after any
desired conditioning steps 203 (FIG. 1), for example, addition
of diluting solution 303, the HGPLS 104 and LGPLS 105
may be forwarded to the desired metal recovery step. The
copper recovery step may include any suitable conditioning
and/or copper recovery method or methods, for example,
electrowinning, precipitation, solution extraction (sometimes
referred to as solvent extraction or liquid ion exchange), ion
exchange, and/or ion flotation, and preferably results in a
relatively pure copper product. Additionally, in accordance
with an exemplary embodiment of the present invention,
diluting solution 303 may be any suitable liquid, for example,
water or atmospheric leach effluent solution, that sufficiently
reduces the copper and acid concentrations to desired levels
to provide desirable equilibrium conditions for solution
extraction 252. In accordance with an exemplary embodiment
of the present invention, sufficient amount of diluting
solution 303 is added to yield an acid concentration ranging
from about 2 to about 25 grams/liter, and more preferably
from about 4 to about 7 grams/liter and a pH preferably
ranging from about pH 1.5 to about pH 2.5 and more preferably
from about pH 1.8 to about pH 2.2, and optimally in the
range ofabout pH 2.0. TheHGPLS 104 andLGPLS 105 may
thereafter be processed, such as for example in accordance
with metal extraction by solution extraction 204.
In many instances, due to variation in incoming metal tenor
in the metal-bearing material 100, it is advantageous to mix
one or more leach solutions prior to solution extraction. As
discussed briefly above, it is sometimes necessary to process
two or more separate leach solution streams from multiple
leach processes at one time. For example, ifan operation has
both a heap leach operation and a pressure or agitated leach
operation, then the heap leach solution, equivalent to the
LGPLS 105, may need to be processed with a more concentrated
pregnant leach solution, HGPLS 104. In this instance,
with reference to FIG. 2A and FIG. 2B and in accordance with
an exemplary embodiment of the present invention, it is not
required that the HGPLS 104 and LGPLS 105 are produced
from the same leaching step 201, flashing step 202, and/or
10
solid-liquid phase separation step 285. Stated another way,
with reference to FIG. 2A and FIG. 2B and in accordance with
an exemplary embodiment ofthe present invention, either the
HGPLS 104 or the LGPLS 105 can be produced by one or
more reactive processing steps 202. Additionally, with reference
to FIG. 2A and FIG. 2B and in accordance with an
exemplary embodiment of the present invention, multiple
controlled grinding steps 200, flashing steps 202, and/or
solid-liquid phase separation steps 285 can be utilized to
10 produce either the HGPLS 104 or the LGPLS 105.
As mentioned above, the metal tenor in the metal-bearing
material 100 can vary greatly over the course of operating a
metal recovery plant. Due to this variation, both primary and
secondary metal recovery processes can evidence losses in
15 efficiency and overall processing yields. One reason for these
losses is the inability to control and tune the metal tenor in the
raffinate from solution extraction of the LGPLS extraction,
low grade raffinate. For example, low grade raffinate is preferably
subjected to a selective precipitation process wherein
20 all metal ions except for those of the secondary metal to be
recovered, for example cobalt, are eliminated from the process
stream by precipitating them as solids. The precipitated
primary metal solids may be recycled to the reactive step.
These precipitated solids may have a high probability of
25 being rendered unrecoverable depending on the precipitating
mechanism employed. In the instance where there is high
primary metal tenor in the low grade raffinate, the amount of
precipitated primary metal solids recycled to the reactive step
may increase. This increase in precipitated metal solids may
30 lead to process inefficiencies due to high circulating loads in
process steps 202 and 204 (FIG. 2B).
Similarly, the inability to control and tune the metal tenor
in the low grade raffinate directly affects the costs associated
with the secondary metal recovery processes. For instance,
35 low metal tenors in the low grade raffinate require less reagent
to effect precipitation (operating cost savings), thus smaller
equipment can be used to recycle the copper precipitate (capital
cost savings).
The present metal recovery process with single extraction
40 plant advantageously allows for control and tuning ofthe low
grade raffinate. Moreover, the solution extraction process
204, described in detail below, preferably, allows for control
and tuning of the low grade raffinate by adjustment of the
barren organic flow rate and/or adjustment of the reagent
45 content and/or adjustment of the flow of the feed material
and/or adjusting the metal content by blending or dilution,
and/or any combinations thereof. It should be understood that
any of these parameters or others may be advantageously
adjusted or controlled as may be desired to suitably adjust the
50 copper flux to the reactive process. Additionally, in accordance
with an exemplary embodiment, the overall efficiency
of the reactive process may be influenced by blending the
primary metal solids precipitated from the low grade raffinate
with high grade raffinate prior to recycling to the reactive
55 process step.
By making any ofthese adjustments to control and tune the
metal tenor in the low grade raffinate, the low grade raffinate
should preferably contain very limited amounts of the primary
metal and allows for efficient secondary metal process-
60 ing. Additionally, the metal recovery process and solution
extraction plant described below, allows plant operators to
maintain a substantially controlled metal concentration in
both the LGPLS stream and the low grade raffinate stream.
Generally, in accordance with exemplary embodiments of
65 the present invention, the controllable process within solution
extraction plant 204 comprises (a) providing a HGPLS to a
solution extractor unit within a single solution extraction
US 8,003,064 B2
11
plant, (b) producing high grade raffinate and a metal-loaded
organic solution by contacting the high grade leach solution
with a partially loaded organic solution in the solution extractor,
(c) providing a LGPLS to a different solution extractor
unit within the same solution extraction plant, and (d) producing
a low grade raffinate and the partially loaded organic
solution by contacting the LGPLS with a barren organic flow
containing a metal-specific extraction reagent.
As discussed above, in accordance with the various
embodiments ofthe present invention, the flow rate and concentration
of the barren organic flow containing a metalspecific
extraction reagent can be altered based on the incoming
metal ore quality to maintain a constant concentration of
metal in the low grade raffinate, allowing for efficient secondary
processing of other metals, including but not limited to
cobalt recovery. Because both the HGPLS and LGPLS
streams are treated in one facility, the metal content of the
LGPLS may be controlled and held constant by adjusting
LGPLS rate according to grade, with the excess being
blended with the HGPLS.
In this regard, solution extraction plant 204 of FIG. 2 is
described in greater detail in FIG. 3. In accordance with an
exemplary embodiment of the present invention, with reference
to FIG. 3, the HGPLS 104 is provided to a high grade
solution extractor unit 209 and the LGPLS 105 is provided to
a low grade solution extractor unit 211. In accordance with
this exemplary embodiment ofthe present invention, HGPLS
104 has a greater concentration ofmetal than the LGPLS 105.
In accordance with this exemplary embodiment ofthe present
invention, the LGPLS 105 has a concentration of metal
greater than about 20% of the concentration of metal in the
HGPLS 104. Preferably, in accordance with this exemplary
embodiment of the present invention, the LGPLS 105 has a
concentration ofmetal greater than about 40% ofthe concentration
ofmetal in the HGPLS 104. Most preferably, in accordance
with this exemplary embodiment ofthe present invention,
the LGPLS 105 has a concentration ofmetal greater than
about 50% of the concentration of metal in the HGPLS 104.
As discussed briefly above, in accordance with exemplary
embodiments of the present invention, the LGPLS 105 is
contacted with a barren organic flow containing a metalspecific
extraction reagent 401, for example, an aldoxime
and/or ketoxime. The barren organic flow containing a metalspecific
extraction reagent 401 extracts at least one primary
metal value from the aqueous phase of the LGPLS 105 into
the organic phase. In accordance with exemplary embodiments
of the present invention, the metal-specific extraction
reagent is supplied by external feed 305. More specifically, in
accordance with another exemplary embodiment of the
present invention, the LGPLS 105 is contacted with the barren
organic flow 401 in low grade solution extractor unit 211.
It should be understood that the solution extractor unit 211 is
only an exemplary reference andmay comprise multiple solution
extractor units.
Further, in accordance with this exemplary embodiment of
the present invention, upon extraction of the at least one
primary metal value from the aqueous phase of the LGPLS
105, a low grade raffinate 281 and a partially loaded organic
solution 400 are produced. In accordance with this exemplary
embodiment ofthe present invention, low grade raffinate 281
is an aqueous stream containing at least one secondary metal
values and containing very low primary metal tenor, thus the
low grade raffinate is suitable for secondary metal recovery
207 as discussed above with reference to FIG. 1 and further
exemplified in FIG. 2B.
Secondly, in accordance with this exemplary embodiment
ofthe present invention, the partially loaded organic solution
12
400 may be contacted with the HGPLS 104 to produce a
metal-loaded organic solution 402 and a high grade raffinate
304. Similarly, with reference to FIG. 3 and in accordance
with exemplary embodiments of the present invention, the
HGPLS 104 is contacted with the partially loaded organic
solution 400 in high grade solution extractor unit 209. As will
be discussed in detail below, in accordance with exemplary
embodiments of the present invention, metal-loaded organic
solution 402 is forwarded to at least one stripping unit 210 for
10 recovery of at least one metal value. It should be understood
that the solution extractor unit 209 is only an exemplary
reference and may comprise multiple solution extractor units.
As discussed previously, it is desirable to produce a metalloaded
organic solution 402 with high metal tenor, which is
15 suitably conditioned for metal recovery by stripping and electrowinning.
Additionally, it is desirable to produce a low
grade raffinate 281, which contains very low primary metal
tenor and is suitable for secondary metal extraction. In order
to accomplish this, with reference to FIG. 3 and in accordance
20 with exemplary embodiments of the present invention, the
barren organic flow rate may be varied in correlation to the
grade of the incoming metal-bearing material and may be
produced in one or more stripping units 210. Additionally, in
accordance with exemplary embodiments of the present
25 invention, any metal-specific extraction reagent may be supplied
by external feed 305 to the stripping units 210 or any
time prior to contacting the LGPLS 105. In accordance with
exemplary embodiments ofthe present invention, the concentration
of the metal-specific extraction reagent 305 may be
30 varied in correlation to the grade of the incoming metalbearing
material.
With reference to FIG. 3 and in accordance with exemplary
embodiments of the present invention, the partially loaded
organic solution 400 may be subjected to an optional strip-
35 ping unit 210 prior to contacting the HGPLS 104. This intermediate
optional stripping unit 210 may increase the extraction
effectiveness of the organic solution 400, thereby
allowing for a lower reagent concentration without sacrificing
metal extraction efficiency. It should be understood that this
40 disclosure teaches, inter alia, any number of solution extractor
units and any number of stripping units in any configuration.
As mentioned above, in accordance with exemplary
embodiments of the present invention, the metal-loaded
45 organic solution 402, preferably containing a high metal
tenor, is subjected to stripping unit 210 and at least one metal
value is stripped from the metal-loaded organic solution 402.
In accordance with exemplary embodiments of the present
invention, at least one metal value is stripped from the metal-
50 loaded organic solution 402 by using any fluid suitable for
stripping metal values from a metal-loaded organic solution,
preferably lean electrolyte 306 recycled from an electrowinning
circuit 216 (FIG. 2B). Optionally, in accordance with
exemplary embodiments ofthe present invention, the metal-
55 loaded organic solution 402 is subjected to a wash stage 212
prior to being stripped in stripping unit 210.
High grade raffinate 304 from solution extraction plant 204
(FIG. 2B) may be used beneficially in a number of ways. For
example, all or a portion of high grade raffinate 304 maybe
60 recycled to any leaching step 201 for temperature control or
may be used in atmospheric leaching, pressure leaching,
whole ore leaching, agitation leaching, heap leaching, stockpile
leaching, pad leaching, thin-layer leaching, vat leaching,
and/or may be used for a combination thereof at either ambi-
65 ent or elevated temperatures. The use of high grade raffinate
304 in heap leaching operations may be beneficial because
the acid and ferric iron values contained in raffinate 304 can
US 8,003,064 B2
13 14
depicted in FIG. 4, low grade solution extractor unit 211 is
separated from the high grade solution series solution extractor
unit 209 by at least one serial solution extractor unit 213.
Additionally, the low grade solution extractor unit 211 is
separated from the stripping unit 210 by at least on serial
solution extractor unit 204.
More precisely, with reference to FIG. 4 and the exemplary
embodiment, the low grade solution extractor unit 211 and
solution extractor unit 214 are in a series configuration. Addi-
10 tionally, the high grade solution extractor unit 209 and solution
extractor unit 213 are in a series configuration. Moreover,
it should be understood that it is not the number of solution
extraction units employed, but the sequence in which they are
configured, thus any number of solution extraction units can
15 be employed and are contemplated herein. Further, as illustrated
by FIG. 3, the high grade extractor units may optionally
be separated from the low grade extractor units by an intermediate
strip unit 210 (FIG. 3), if solution chemistry and
process kinetics make it advantageous to do so. Additionally,
20 an organic wash stage 212 (FIG. 3) may be added prior to
stripping if necessitated by solution chemistry.
Returning to FIG. 2B, in accordance with the various
embodiments ofthe present invention, metal-bearing solution
stream, or rich electrolyte, 276 from solution extraction plant
25 204 may be sent to an electrolyte recycle tank 205. The
electrolyte recycle tank may suitably facilitate process control
for an electrowinning circuit 216, as will be discussed in
greater detail below. Metal-bearing solution stream 276,
which can contain from about 25 to about 75 grams/liter of
30 copper and from about 145 to about 180 grams/liter acid, is
preferably blended with a lean electrolyte 306 (i.e., electrolyte
that has already been through the metal recovery phase
and has had a portion of its dissolved copper removed) and
makeup fluid 215, such as, for example, water, in the electro-
35 Iyte recycle tank 205 at a ratio suitable to yield a product
stream 108, the conditions of which may be chosen to optimize
the resultant product of electrowinning step 216.
In accordance with the various embodiments ofthe present
invention, the metal composition of product stream 108 is
40 maintained substantially constant at a value from about 20 to
about 60 grams/liter, more preferably at a value from about 30
to about 50 grams/liter. Metal values from the product stream
108 are removed during electrowinning circuit 216 to yield a
pure, cathode metal product 217. As mentioned above, in
45 accordance with the various embodiments of the present
invention, electrowinning circuit 216 produces pure, cathode
metal product 217 and lean electrolyte 306, which can be
recycled to the electrolyte recycle tank 205, the solution
extraction plant 204, and/or the leaching step 201.
It should be appreciated that in accordance with the various
aspects of the invention, a process wherein, upon proper
conditioning of the copper-bearing solution, a high quality,
uniformly-plated cathode copper product may be realized
without subjecting the copper-bearing solution to solution
55 extraction prior to entering the electrowinning circuit is
within the scope of the present invention. As previously
noted, careful control ofthe conditions ofthe copper-bearing
solution entering an electrowinning circuit-especially
maintenance of a substantially constant copper composition
60 in the stream---can enhance the quality of the electrowon
copper by, among other things, enabling even plating of copper
on the cathode and avoidance of surface porosity in the
cathode copper, which degrades the copper product and thus
diminishes its economic value. In accordance with this aspect
65 of the invention, such process control can be accomplished
using any of a variety of techniques and equipment configurations,
so long as the chosen system and/or method maintain
act to optimize the potential for leaching oxide and/or sulfide
ores that commonly dominate agitation leaching, heap leaching,
stockpile leaching, pad leaching, thin-layer leaching and/
or vat leaching operations. That is, the ferric and acid concentrations
of raffinate 304 may be used to optimize the Eh
and pH ofheap leaching operations. It should be appreciated
that the properties of high grade raffinate 304, such as component
concentrations, may be adjusted in accordance with
the desired use ofhigh grade raffinate 304.
Additionally, in accordance with the various embodiments
ofthe present invention, low grade raffinate 107 from solution
extraction plant 204 (FIG. 2B) may be sent to secondary
metal processing 207 (FIG. 1) for other secondary metals,
including, but not limited to silver, platinum group metals,
molybdenum, zinc, nickel, cobalt, uranium, rhenium, rare
earth and actinide metals. As mentioned above, preferred
embodiments of the present invention advantageously provide
for maintenance of a constant metal tenor in both the
high grade and low grade raffinate. This direct control facilitates
a known and substantially controlled metal precipitate
recycle, increasing operating efficiency, potential limiting
metal losses, and reducing recycle equipment size and subsequent
capital costs. Therefore, in accordance with the various
embodiments of the present invention, the flow rate and
concentration of the organic flow containing a metal-specific
extraction reagent 401 can be altered based on the incoming
metal-bearing ore quality to maintain a constant concentration
(tenor) ofmetal in the low grade raffinate 281. To effectuate
such direct control either the metal concentration and/or
flow rate of any organic and/or aqueous flow in the process
may be controlled, thus enabling extraction to take place
under tightly controlled conditions. Specifically, the amount
of high grade raffinate which is recycled to a leach step may
be controlled. This ability to maintain the metal tenor of the
low grade raffinate 107 allows for the efficient recovery of
cobalt or other secondary metal values at any given metallic
ore quality by removing a majority of primary metals, which
would interfere with the recovery of other secondary metal,
from the low grade raffinate 107.
With reference to FIG. 3, the present invention allows the
extraction circuit for the primary metal value to be tuned and
optimized, both in terms of metallurgical performance and
capital and operating costs. There is a trade off between
achieving optimum metallurgical performance and minimizing
the capital costs of the operating facility. The decisions
made regarding this trade off are based on the performance
and cost ofthe metal-specific extraction reagent employed as
well as the chemistry ofthe pregnant leach solution streams to
be treated. For example, the use ofa metal-specific extraction
reagent with exhibits rapid extraction kinetics may minimize 50
the number of sequential extractors needed to achieve a satisfactory
level of metal recovery. The presence of iron, manganese,
or chloride in the pregnant leach solution streams
may require the use of a wash stage prior to stripping. The
number and placement of stripping units is decided based on
the stripping kinetics of the extraction reagent as well as its
maximum metal loading capacity. Accordingly, various configurations
are within the scope of the present invention.
Moreover, in accordance with this exemplary embodiment
ofthe present invention, multiple solution extractor units can
be utilized in any configuration, preferably series or parallel
configurations, within the same solution extraction plant 204.
More specifically, the high grade solution extractor unit 209 is
suitably connected in parallel to the low grade solution
extractor unit 211 by a common organic flow containing a
metal-specific extraction reagent. For example, in accordance
with an exemplary embodiment of the present invention, as
US 8,003,064 B2
15 16
8. The process of claim 1, wherein said low grade raffinate
is subjected to secondary extraction processing.
9. The process of claim 8, wherein the low grade raffinate
comprises a secondary metal selected from the group consisting
ofgold, silver, platinum group metals, molybdenum, zinc,
nickel, cobalt, uranium, rhenium, rare earth metals, and
actinide metals.
10. A controlled copper leach and recovery process comprising:
providing a high grade pregnant leach solution to a first
solution extractor unit;
producing a high grade raffinate and a metal-loaded
organic solution by contacting said high grade pregnant
leach solution with a partially loaded organic solution;
providing a low grade pregnant leach solution to a second
solution extractor unit,
wherein said high grade pregnant leach solution has a
greater concentration ofmetal than said low grade pregnant
leach solution and wherein said first solution
extractor unit and said second solution extractor unit are
in the same solution extraction plant;
producing a low grade raffinate and said partially loaded
organic solution by contacting said low grade pregnant
leach solution with a barren organic flow; and
producing said barren organic flow by stripping at least one
metal value from said metal-loaded organic solution in
at least one stripping unit within said solution extraction
plant.
11. The process of claim 10, further comprising adding a
metal-specific extraction reagent to said barren organic flow
35 prior to contacting with said low grade pregnant leach solution.
50
12. The process ofclaim 10, wherein said high grade pregnant
leach solution is generated from at least one of an atmospheric
leaching process, a pressure leaching process, an
agitation leaching process, a heap leaching process, a stockpile
leaching process, a pad leaching process, a thin-layer
leaching process, and a vat leaching process.
13. The process of claim 10, wherein said high grade raffinate
is recycled to at least one of a atmospheric leaching
process, a pressure leaching process, an agitation leaching
process, a heap leaching process, a stockpile leaching process,
a pad leaching process, a thin-layer leaching process,
and a vat leaching process.
14. The process of claim 10, wherein said low grade raffinate
is subjected to secondary extraction processing.
15. The process of claim 14, wherein the low grade raffinate
comprises a secondary metal selected from the group
consisting of silver, platinum group metals, molybdenum,
55 zinc, nickel, cobalt, uranium, rhenium, rare earth metals, and
actinide metals.
16. The process ofclaim 10, wherein said concentration of
metal in said high grade pregnant leach solution is greater
than about 20% of the concentration of metal in said low
grade pregnant leach solution.
17. The process of claim 10, wherein said first solution
extraction unit is connected to said second solution extraction
unit in parallel.
18. The process ofclaim 10, wherein at least one stripping
unit is positioned between said first solution extractor unit and
said second solution extractor unit.
What is claimed is:
1. A controlled copper leach and recovery process com- 25
prising:
subjecting a metal-bearing material to a reactive process to
liberate at least one metal value from said metal-bearing
material;
obtaining a product slurry from said reactive process, 30
wherein at least two metal values are present in said
product slurry;
producing a high grade pregnant leach solution and a low
grade pregnant leach solution by subjecting said product
slurry to a solid-liquid separation process;
providing said high grade pregnant leach solution to a
solution extraction plant comprising at least two solution
extractors and at least two stripping units;
producing a high grade raffinate and a metal-loaded solution
by contacting said high grade pregnant leach solu- 40
tion with a partially loaded organic solution in said solution
extraction plant;
providing said low grade pregnant leach solution to said
solution extraction plant, wherein said low grade pregnant
leach solution comprises a lower metal concentra- 45
tion than said high grade pregnant leach solution; and
producing a low grade raffinate and said partially loaded
organic solution by contacting said low grade pregnant
leach solution with a barren organic flow for extracting
said at least one metal value.
2. The process of claim 1, wherein said reactive process
comprises a leaching process.
3. The process ofclaim 1, wherein at least one metal value
is stripped from said metal-loaded solution in at least one
stripping unit.
4. The process ofclaim 3, wherein said barren organic flow
is produced by stripping said at least one metal value in at
least one stripping unit.
5. The process of claim 4, wherein said partially loaded
organic solution is subjected to at least one stripping unit prior 60
to contacting said high grade pregnant leach solution.
6. The process ofclaim 2, wherein said high grade raffinate
is recycled to a leaching process.
7. The process of claim 1, wherein the concentration of
metal in low grade raffinate is held substantially constant by 65
varying the flow rate of said barren organic flow or reagent
concentration.
a sufficiently constant feed stream to the electrowinning circuit.
As those skilled in the art are aware, a variety ofmethods
and apparatus are available for the electrowinning of copper
and other metal values, any ofwhich may be suitable for use
in accordance with the present invention, provided the requisite
process parameters for the chosen method or apparatus
are satisfied.
It is believed that the disclosure set forth above encompasses
at least one distinct invention with independent utility.
While the invention has been disclosed in the exemplary 10
forms, the specific embodiments thereof as disclosed and
illustrated herein are not to be considered in a limiting sense
as numerous variations are possible. The subject matter ofthe
inventions includes all novel and non-obvious combinations 15
and sub combinations ofthe various elements, features, functions
and/or properties disclosed herein.
The method and system described herein may be implemented
to recover copper and other metals in a controlled
manner. Other advantages and features ofthe present systems 20
and methods may be appreciated from the disclosure herein
and the implementation ofthe method and system.
17
US 8,003,064 B2
18
19. The process of claim 10, wherein at least one solution
extractor unit separates said first solution extractor unit from
said second solution extractor unit.
20. The process of claim 10, further comprising stripping
said metal-loaded organic solution in at least one stripping
unit to produce a metal-rich solution and a barren organic
solution.
21. The process of claim 20, further comprising sending
said metal-rich solution to an electrowinning process.
22. The process of claim 20, further comprising washing
said metal-loaded organic solution in at least one wash stage
prior to said stripping step.
23. The process of claim 10, wherein the concentration of
metal in low grade raffinate is held substantially constant by
varying the flow rate of said barren organic flow.
24. The process of claim 10, wherein the concentration of
metal in said low grade raffinate is controlled by altering the
flow rate of at least one of said high grade pregnant leach
solution and said low grade pregnant leach solution.
25. The process ofclaim 10, wherein said at least one metal
value is stripped from metal-loaded solution by at least one of
10 a lean electrolyte from an electrowinning process and a sulfuric
acid solution.
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