U.S. patent application number 13/024801 was filed with the patent office on 2011-08-11 for ion exchange cobalt recovery.
Invention is credited to Charles Marston, Neil Nebeker, Matthew Rodgers.
Application Number | 20110195000 13/024801 |
Document ID | / |
Family ID | 44353883 |
Filed Date | 2011-08-11 |
United States Patent
Application |
20110195000 |
Kind Code |
A1 |
Nebeker; Neil ; et
al. |
August 11, 2011 |
ION EXCHANGE COBALT RECOVERY
Abstract
Method of ion exchange cobalt recovery. Raffinate including
cobalt, zinc, copper, nickel and ferric iron is produced. In the
raffinate, the pH is raised, the solids are removed and ferric iron
is reduced. A copper recovery ion exchange unit is loaded with ion
exchange resin selective for copper. Raffinate is fed into the
copper recovery ion exchange unit which is regenerated to recover
substantially all copper. A cobalt/nickel/zinc recovery ion
exchange unit is loaded with another ion exchange resin selective
for cobalt. Raffinate is fed into the cobalt/nickel/zinc recovery
ion exchange unit, the ion exchange resin holding cobalt, zinc and
nickel, and then displaced. Cobalt/zinc eluent is fed into the
cobalt/zinc/nickel recovery ion exchange unit to elute the cobalt
and zinc in a cobalt/zinc solution, and then displaced. Nickel
eluent is fed into the cobalt/zinc/nickel recovery ion exchange
unit to elute the nickel.
Inventors: |
Nebeker; Neil; (Hayden,
AZ) ; Rodgers; Matthew; (Midland, MI) ;
Marston; Charles; (Midland, MI) |
Family ID: |
44353883 |
Appl. No.: |
13/024801 |
Filed: |
February 10, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61303022 |
Feb 10, 2010 |
|
|
|
Current U.S.
Class: |
423/139 |
Current CPC
Class: |
C22B 23/0484 20130101;
Y02P 10/234 20151101; C01G 51/003 20130101; C22B 3/42 20130101;
Y02P 10/20 20151101; C01P 2006/80 20130101 |
Class at
Publication: |
423/139 |
International
Class: |
C01G 51/00 20060101
C01G051/00 |
Claims
1. A method of ion exchange cobalt recovery from raffinate,
comprising: producing raffinate, the raffinate including at least
cobalt, zinc, copper, nickel and ferric iron; raising a pH of the
raffinate; removing solids from the raffinate; reducing ferric iron
to ferrous iron; loading a copper recovery ion exchange unit with
an ion exchange resin selective for copper; feeding the raffinate
into the copper recovery ion exchange unit in a first direction;
regenerating the copper recovery ion exchange unit to recover
substantially all the copper from the ion exchange resin selective
for copper; loading a cobalt/nickel/zinc recovery ion exchange unit
with a second ion exchange resin selective at least for cobalt;
feeding the raffinate into the cobalt/nickel/zinc recovery ion
exchange unit in the first direction, the second ion exchange resin
holding cobalt, zinc and nickel; displacing the raffinate from the
cobalt/nickel/zinc recovery ion exchange unit; feeding cobalt/zinc
eluent into the cobalt/zinc/nickel recovery ion exchange unit to
elute the cobalt and zinc in a cobalt/zinc solution; displacing the
cobalt/zinc eluent in the cobalt/zinc/nickel recovery ion exchange
unit; and feeding nickel eluent into the cobalt/zinc/nickel
recovery ion exchange unit to elute the nickel.
2. The method of claim 1, wherein the regenerating comprises
feeding a strong acid into the copper recovery ion exchange unit in
a second direction, the second direction being countercurrent to
the first direction.
3. The method of claim 1, wherein the feeding the raffinate into
the copper removal ion exchange unit comprises feeding at a first
rate and wherein the regenerating comprises regenerating at a
second rate, the second rate being slower than the first rate.
4. The method of claim 1, wherein the ion exchange resin selective
for copper is a hydroxypropylpicolylamine resin.
5. The method of claim 1, further comprising displacing the nickel
eluent.
6. The method of claim 5, wherein the displacing the nickel eluent
comprises one selected from the group consisting of displacing with
water, displacing with nickel eluent, and displacing with recycled
nickel eluent/eluate.
7. The method of claim 1, wherein the second ion exchange resin is
a bispicolylamine functionalized resin.
8. The method of claim 1, wherein the feeding cobalt/zinc eluent
comprises feeding cobalt/zinc eluent in a second direction, the
second direction being countercurrent to the first direction.
9. The method of claim 1, further comprising separating the zinc
from the cobalt in the cobalt/zinc solution.
10. The method of claim 9, wherein the separating comprises using a
basic anion exchange to remove anionic zinc.
11. The method of claim 10, wherein the separating comprises adding
a salt to the cobalt/zinc solution.
12. The method of claim 1, wherein the raising the pH of the
raffinate comprises raising the pH to between about 3.0 and about
3.5.
13. The method of claim 1, wherein the removing solids from the
raffinate comprises filtering the raffinate.
14. The method of claim 1, wherein the raising the pH of the
raffinate comprises adding calcium oxide or calcium carbonate to
the raffinate.
15. The method of claim 1, wherein the reducing ferric iron
comprises adding sodium sulfite to the raffinate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to provisional U.S. Patent
application Ser. No. 61/303,022, filed Feb. 10, 2010, which is
incorporated by reference as though fully set forth herein.
FIELD OF INVENTION
[0002] This invention relates to methods for extracting metals from
raw ore generally and more specifically to processes for recovering
cobalt from copper solvent extraction raffinate with ion exchange
technology.
BACKGROUND OF THE INVENTION
[0003] In mining operations, raw ore contains metals of value that
are recoverable. Several known techniques, including solvent
extraction ("SX") are used to chemically separate metals from raw
ore. In SX, metal ions, for example, copper ions, are leached or
otherwise extracted from raw copper ore using chemical agents, such
as strong acid. The copper is then plated out of solution onto
stainless steel sheets using electrowinning ("EW") processes.
Cobalt, a naturally occurring valuable metal, is added to many
copper EW tankhouses to reduce not only corrosion of insoluble lead
anodes but also the overvoltage of the oxygen evolution from the
anodes. The byproduct of SX is raffinate in which certain metals,
including cobalt, may remain after the metal of primary interest,
e.g., copper, is extracted from the pregnant leach solution
("PLS").
BRIEF SUMMARY OF THE INVENTION
[0004] The following summary is provided as a brief overview of the
claimed method and apparatus. It should not limit the invention in
any respect, with a detailed and fully-enabling disclosure being
set forth in the Detailed Description of the Invention section.
Likewise, the invention shall not be restricted to any numerical
parameters, processing equipment, chemical reagents, operational
conditions, and other variables unless otherwise stated herein.
[0005] According to one embodiment of the present invention, a
method of ion exchange cobalt recovery from raffinate, comprises:
producing raffinate that includes at least cobalt, zinc, copper,
nickel and ferric iron; raising a pH of the raffinate; removing
solids from the raffinate; reducing ferric iron to ferrous iron;
loading a copper recovery ion exchange unit with an ion exchange
resin selective for copper; feeding the raffinate into the copper
recovery ion exchange unit in a first direction; regenerating the
copper recovery ion exchange unit to recover substantially all the
copper from the ion exchange resin selective for copper; loading a
cobalt/nickel/zinc recovery ion exchange unit with a second ion
exchange resin selective at least for cobalt; feeding the raffinate
into the cobalt/nickel/zinc recovery ion exchange unit in the first
direction, the second ion exchange resin holding cobalt, zinc and
nickel; displacing the raffinate from the cobalt/nickel/zinc
recovery ion exchange unit; feeding cobalt/zinc eluent into the
cobalt/zinc/nickel recovery ion exchange unit to elute the cobalt
and zinc in a cobalt/zinc solution; displacing the cobalt/zinc
eluent in the cobalt/zinc/nickel recovery ion exchange unit; and
feeding nickel eluent into the cobalt/zinc/nickel recovery ion
exchange unit to elute the nickel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The accompanying figures, which are incorporated herein and
form a part of the specification, illustrate various embodiments of
the present invention and, together with the description, serve to
explain the invention. In the figures:
[0007] FIG. 1 is a flow sheet illustrating apparatus of the present
invention for recovering cobalt and nickel from raffinate;
[0008] FIG. 2 is a flow sheet illustrating apparatus of the present
invention for recovering cobalt, zinc and nickel from
raffinate;
[0009] FIG. 3 is a flow sheet illustrating apparatus of the present
invention for recovering cobalt, zinc and nickel from
raffinate;
[0010] FIG. 4 is a flow sheet illustrating apparatus of the present
invention for recovering cobalt, zinc and nickel from
raffinate;
[0011] FIG. 5 illustrates an embodiment of a method for recovering
copper, nickel and cobalt from raffinate;
[0012] FIG. 6 illustrates an embodiment of a method for recovering
copper, nickel, cobalt and zinc from raffinate;
[0013] FIG. 7 is a graph showing affinities of bispicolylamine
resin for various metals at different pH levels;
[0014] FIG. 8 is a graph showing copper recovery according to one
embodiment of the invention;
[0015] FIG. 9 shows graphs of the loading and elution of metals
from Example 1 according to an embodiment of the present
invention;
[0016] FIG. 10 shows graphs of the loading and elution of metals
from Example 3 according to an embodiment of the present
invention;
[0017] FIG. 11 shows graphs of the loading and elution of metals
from Example 4 according to an embodiment of the present
invention;
[0018] FIG. 12 is a of the elution of metals from Example 5
according to an embodiment of the present invention;
[0019] FIG. 13 shows graphs of the loading and elution of metals
from Example 6 according to an embodiment of the present
invention;
[0020] FIG. 14 shows graphs of the loading and elution of metals
from Example 10 according to an embodiment of the present
invention;
[0021] FIG. 15 is a graph showing loading and elution of metals
from Example 11 according to an embodiment of the present
invention;
[0022] FIG. 16 is a graph showing copper loading in Example 12
according to an embodiment of the present invention;
[0023] FIG. 17 is a graph showing copper elution in Example 12
according to an embodiment of the present invention;
[0024] FIG. 18 is a graph showing copper elution in Example 12
according to an embodiment of the present invention; and
[0025] FIG. 19 is a graph showing copper elution in Example 12
according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Although SX performs well in extracting copper from PLS, it
is not an efficient or economical method for recovering cobalt from
mine leach or raffinate 13 streams. Cobalt concentration in
raffinate 13 is so dilute that the SX method cannot be used for
extraction. Also, aluminum interferes with SX by generating a large
amount of crud in the extraction stages.
[0027] The present invention provides a means for recovering cobalt
and other metals using a combination of SX and ion exchange
methods, which may yield significant operational metal. By
recovering cobalt and other metals, these metals may be recycled
into the SX process. Therefore, it may be desirable to remove
cobalt and other metals from raffinate 13 using the apparatus 10
and method 100 of the present invention.
[0028] The present invention comprises apparatus 10 and method 100
for extracting cobalt from raffinate 13 using ion exchange and
elution processes as are described more fully below. Apparatus 10
and method 100 of the present invention may be a function of the
various constituents of raffinate 13, which may depend not only on
the constituents of the metal ore, but also on the reagents used
during SX. In one embodiment, raffinate 13 comprises at least
copper, cobalt, nickel, iron (ferrous and ferric). In other
embodiments, raffinate 13 may also comprise any or all of ferrous
iron, magnesium or zinc.
[0029] Various embodiments of apparatus 10 will now be described
with reference to the drawing figures. In an embodiment shown in
FIG. 1 in which the raffinate 13 comprises at least copper, cobalt,
nickel, magnesium and iron, apparatus 10 comprises pretreatment
system 11, ion exchange system 19, and eluate system 23.
[0030] Pretreatment system 11 allows raffinate 13 to be pretreated
by adjusting the pH level and reducing iron, to prepare raffinate
13 for the ion exchange processes. As shown in FIG. 1, pretreatment
system 11 comprises raffinate tank 12, process tank 14 and drum
filter 16. In another embodiment, in which raffinate 13 comprises
organic, pretreatment 11 may also include vessel(s) (not shown) for
organic removal using adsorbent resins or chelating resins or a
combination as may be appropriate given the total organic carbon
composition of raffinate 13.
[0031] Raffinate tank 12 is sized to receive raffinate 13 generated
through copper SX. Raffinate tank 12 is fluidically connected to
process tank 14. As used herein, "fluidically connected" means
connected using pipes, conduits, valves, pumps and other similar
apparatus that provide for the movement of fluid in systems of this
type. Once raffinate 13 leaves raffinate tank 12, raffinate 13
enters process tank 14, which is sized to receive, not only
raffinate 13, but also other reagents to aid in the processes to be
performed in process tank 14. As mentioned above, in process tank
14, the pH of raffinate 13 may be adjusted and iron may be reduced.
In the embodiment shown in FIG. 1, in process tank 14, the pH of
raffinate 13 may be raised from between about 1.45 to about 1.8 to
about 3.0 to about 3.5, preferably about 3.0 to about 3.2, in
process tank 14, by adding calcium oxide (CaO), calcium carbonate
(CaCO.sub.3) or other similar reagents contained in a vessel (not
shown) connected to process tank 14. Depending on the composition
of raffinate 13 involved, in other embodiments, pH may be adjusted
up or down to obtain the desired pH, as would be familiar to one of
ordinary skill in the art after becoming familiar with the
teachings of this invention; in other embodiments, the pH may not
need to be adjusted at all. In the embodiments disclosed herein,
the desired pH is in the range of about 3.0 to about 3.5,
preferably between about 3.0 and about 3.2; based on the ion
exchange resins used, a different pH may be preferred.
[0032] In the embodiment shown in FIG. 1, raising the pH by adding
addition of CaO produces solids requiring removal to minimize
clogging of ion exchange system 19. These solids may be removed
using a variety of commercially available coagulants and
flocculents, such as Nalco N8850 coagulant and N7871 flocculent,
which may be added to process tank 14 following pH adjustment. The
coagulant and flocculent are commercially available from Nalco
Company, Tempe Ariz. The coagulants and flocculents may be
contained in a vessel (not shown) connected to process tank 14. The
coagulated solids may then be removed by filtering, such as by
running raffinate 13 through drum filter 16 which is fluidically
connected to process tank 14 to receive the solids removed from
process tank 14. Other known mechanical separation processes may be
used to separate the coagulated solids from raffinate 13. In
another embodiment, an additional filter (e.g., inline cartridge
filter (not shown)) may be added to apparatus 10 immediately
upstream of copper removal ion exchange unit 18.
[0033] In addition to pH level adjustment, iron reduction may also
take place in the process tank 14, as in the embodiment illustrated
in FIG. 1. As explained more fully below, iron reduction may be
beneficial given the affinities for ferric iron or ferrous iron of
the various ion exchange resins selected for the process. See FIG.
7. In the embodiment shown in FIG. 1, iron reduction from ferric
iron to ferrous iron is achieved by addition of sodium sulfite
(Na.sub.2SO.sub.3) or other similar reagents, which may be
contained in a vessel (not shown) connected to process tank 14.
Alternatively, an intermediate tank for iron reduction or other
processes may be provided before raffinate 13 enters ion exchange
system 19. Of course, if the raffinate 13 contains only ferrous
iron, no reduction is necessary.
[0034] Once raffinate 13 has been pretreated 105 according to
embodiments of the present invention, pretreated raffinate 13
enters ion exchange system 19 which is fluidically connected to
process tank 14. In the embodiment shown in FIG. 1, ion exchange
system 19 comprises copper removal ion exchange unit 18 and
cobalt/nickel removal ion exchange unit 22, both of which comprise
multiple resin columns which may be arranged in fixed beds of
lead-lag configuration or in carousel or other configurations as
would be familiar to one of ordinary skill in the art after
becoming familiar with the teachings of the present invention.
[0035] In another embodiment, ion exchange system 19 may comprise
cobalt/nickel/zinc removal ion exchange unit 15. See FIGS. 2-4. In
embodiments described herein, copper removal precedes cobalt/nickel
removal from raffinate 13 because the bispicolylamine
functionalized ion exchange resin that has a high affinity for
cobalt and nickel also has a high affinity for copper. See FIG. 8.
Copper can contaminate the bispicolylamine resin, a chelating
resin, by loading the resin preferentially, requiring ammonia
solutions (as opposed to strong acid solution) to strip out the
copper. Therefore, as shown in FIG. 1, copper removal ion exchange
unit 18 is upstream of cobalt/nickel ion exchange unit 22 in
apparatus 10.
[0036] Copper removal ion exchange unit 18 may be a fixed bed
system loaded with an ion exchange resin with a high affinity for
copper, such as a hydroxypropylpicolylamine functionalized resin, a
chelating resin with high affinity for copper at low pH (e.g.,
between about 3.0 to about 3.5) that can be stripped using strong
acid solutions; it is commercially available as XUS-43605 from The
Dow Chemical Company; however, other similar resins could also be
used. The fixed bed system may be comprise multiple beds in a
lead-lag configuration, as shown in FIG. 1, comprising lead (first)
column 21 and lag (second) column 25 (although the designation of
lead and lag may change during processing depending on which column
is primarily loaded with copper). In various embodiments, copper
removal ion exchange unit 18 may comprise two, three, four or more
beds. Process tank 14 is fluidically connected to the top of the
lead column 21, so that raffinate 13 may be pumped into the top of
lead column 21, exiting the bottom of lead column 21 and entering
the top of lag column 25. Copper removal ion exchange unit 18
loaded with ion exchange resin selective for copper removes
substantially all copper in raffinate 13. "Substantially all" means
from about 95% to about 100% of the copper in raffinate 13.
Preferably, all copper is removed, so that the raffinate 13 exiting
the bottom of the lag column 25 is copper-free. As is explained in
more detail below, copper may be stripped and the beds (e.g., lead
column 21 and lag column 25) regenerated using copper eluent
comprising sulfuric acid (H.sub.2SO.sub.4) or a lean electroyte
(containing copper and strong acid, such as H.sub.2SO.sub.4). In an
embodiment comprising lead column 21 and lag column 25,
regeneration may be accomplished countercurrent to the direction of
loading with a 20% H.sub.2SO.sub.4 solution. See FIG. 1. Copper
eluent may be contained in copper eluent tank 17, which is part of
eluent system 23 and is fluidically connected to copper removal ion
exchange unit 18. The copper is recovered as copper sulfate
(CuSO.sub.4) in solution which is removed to copper recovery
vessel. Copper recovery vessel 20 is fluidically connected to
copper removal ion exchange unit 18. Copper recovery vessel 20 may
comprise an intermediate tank or the actual copper EW
tankhouse.
[0037] Raffinate 13 is then conveyed to cobalt/nickel removal ion
exchange unit 22 which is fluidically connected to copper removal
ion exchange unit 18. Cobalt/nickel removal ion exchange unit 22
may be a fixed bed system comprising multiple columns loaded with
an ion exchange resin with a high affinity for both cobalt and
nickel, such as bispicolylamine functionalized ion exchange resin
which is commercially available as XUS-43578 from The Dow Chemical
Company, although other similar resins may also be used.
[0038] After full loading of the columns with nickel and cobalt,
nickel and cobalt are stripped by means of eluate system 23. In
addition to copper eluent tank 17, eluate system 23 comprises
cobalt eluent tank 24 and nickel eluent tank 26. Cobalt eluent tank
31 and nickel eluent tank 29 are fluidically connected to
cobalt/nickel removal ion exchange unit 22 so that, at the
appropriate point, either cobalt eluent or nickel eluent can be
added to the cobalt/nickel removal ion exchange unit 22 to strip
either cobalt or nickel from the loaded resin. Since cobalt does
not adhere as strongly to the resin as nickel, cobalt may be
considered easier to remove than nickel, using an acid
concentration weaker than that required to strip the nickel.
Therefore in the embodiment shown in FIGS. 1-4, cobalt is removed
first. Cobalt eluent tank 31 is sized for holding cobalt eluent
which comprises H.sub.2SO.sub.4 in concentration of about 2% to
about 4%, preferably between 2.5% to 3.85%, although weak
concentrations of other strong acids may also be used. As used
herein "strong acid" means hydrochloric acid (HCl), nitric acid
(HNO.sub.3) and perchloric acid (HClO.sub.4), as well as
H.sub.2SO.sub.4. With the addition of cobalt eluent from cobalt
eluent tank 31 to the cobalt/nickel removal ion exchange unit 22,
cobalt is stripped from the resin and conveyed in solution to
cobalt eluate tank 24.
[0039] In an embodiment wherein raffinate 13 comprises zinc, eluate
system 23 further comprises cobalt/zinc eluent tank 27, as shown in
FIGS. 2 and 3. Cobalt/zinc eluent tank 27 is fluidically connected
to cobalt/nickel removal ion exchange unit 22, which in the
embodiment being described also removes zinc using the second ion
exchange resin (e.g., bispicolylamine functionalized ion exchange
resin). Cobalt/zinc eluent tank 27 is sized for holding cobalt/zinc
eluent comprising H.sub.2SO.sub.4 in concentration of about 2% to
about 4% by volume, preferably between 2.5% to 3.85% by volume,
although weak concentrations of other strong acids could be used.
Cobalt/zinc eluent may be the same substance as cobalt eluent
described above. Cobalt and zinc are stripped out together using
cobalt/zinc eluent and are conveyed in solution to cobalt/zinc
eluate tank 28. From there, cobalt may be stripped using various
methods as are described below.
[0040] Nickel is next removed. Nickel eluent tank 29 is sized for
holding nickel eluent which comprises H.sub.2SO.sub.4 in
concentration of about 20% by volume or 200 g/L, although other
high concentrations of strong acid could also be used. With the
addition of nickel eluent from nickel eluent tank 31 to the
cobalt/nickel removal ion exchange unit 22, nickel is stripped from
the resin and conveyed in solution to nickel eluate tank 26.
[0041] Depending on the metals to be recovered from raffinate 13,
in another embodiment of the invention, eluate system 23 may also
comprise additional eluent and eluate tanks fluidically connected
to ion exchange system 19. Additional eluent tanks, such as
cobalt/zinc eluent tank 27, may hold eluent for stripping desired
metals from ion exchange resin. Additional eluate tanks, such as
cobalt/zinc eluate tank 28, may be provided to recover such metals
in solution. Similarly, depending on the particular embodiment of
method 100 carried out, apparatus 10 may also comprise additional
vessels, including rinse, barren, feed, eluent and eluate tanks,
including barren tank 30, nickel eluent rinse water tank 36 and
mass balance tank 34.
[0042] With reference to FIGS. 2 and 3, other embodiments of
apparatus 10 will now be described. Although apparatus 10 comprises
process tank 14, drum filter 16, copper ion exchange unit 18,
copper eluent tank 17 and copper removal vessel 20, FIGS. 2 and 3
focus on ion exchange system 19 and eluate system 23. See also FIG.
4. In the embodiments shown, apparatus 10 comprises raffinate tank
12 which is sized for holding raffinate 13 (e.g., 400 gallons).
Raffinate 13 in this embodiment comprises zinc or zinc and
magnesium, as well as cobalt, nickel and ferrous iron, the copper
having already been removed and the iron having already been
reduced. As shown in FIGS. 2-4, mass balance tank 34' is
fluidically connected to raffinate tank 12 so that raffinate 13 may
be analyzed prior to the point at which raffinate 13 enters
cobalt/nickel/zinc removal ion exchange unit 15; however, mass
balance tank 34' is not required. Raffinate tank 12 is also
fluidically connected to cobalt/nickel/zinc removal ion exchange
unit 15, specifically a first set of five columns 151 that is a
part of the cobalt/nickel/zinc removal ion exchange unit 15. In
another embodiment of the invention, cobalt/nickel/zinc removal ion
exchange unit 15 may be fluidically connected to and receive
raffinate 13 from copper removal ion exchange unit 18.
[0043] As shown in FIG. 2-4, raffinate 13 is then conveyed (e.g.,
pumped) from raffinate tank 12 to cobalt/nickel/zinc removal ion
exchange unit 15, which comprises a carousel equipped with 24
columns 151-159 loaded with an ion exchange resin with a high
affinity for both cobalt and nickel, such as bispicolylamine
functionalized ion exchange resin. The carousel is also connected
to a multiple port valve (not shown), which enables the carousel to
be fluidically connected to other systems, making it part of eluate
system 23, as well. The carousel configuration therefore permits
loading, rinsing and eluting without changing vessels. The multiple
port valve may also be operatively associated with a timer, so that
apparatus 10 can be operated automatically. Other configurations
for the cobalt/nickel/zinc ion exchange unit 15 are also
possible.
[0044] Since raffinate tank 12 is fluidically connected to the
first set of five columns 151, raffinate 13 is pumped through each
column in the first set of five columns 151 in the down-flow
direction. The first set of five columns 151 is arranged in
parallel so that raffinate 13 enters each column at the top,
flowing through to the bottom. As shown in FIGS. 2-4, the
discharged raffinate 13 from the first set of five columns 151 is
collected together and then conveyed (e.g., pumped) through a
second set of five columns 152 arranged in a similar manner to the
first set of five columns 151 so that the raffinate 13 enters each
column at the top, flowing through to the bottom. As shown in FIGS.
2-4, the columns of the cobalt/nickel/zinc removal ion exchange
unit 15 are moving in a first direction (e.g., from right to left
direction as indicated by arrows 38); however, the raffinate 13 is
being fed into the first and second sets of columns 151, 152 in a
second direction countercurrent to the direction of arrows 38
(e.g., left to right as shown on FIGS. 2-4). It is believed that
feeding the raffinate 13 in the second direction countercurrent to
the first direction increases the efficiency of the ion exchange
resin with which the columns 151-159 are loaded.
[0045] Raffinate 13 discharged from the second set of columns 152
is collected and conveyed to barren tank 30, which is fluidically
connected to receive outflow from the second set of columns 152.
Barren tank 30 is fluidically connected to mass balance tank 34''
which is provided so that the composition of the discharged
raffinate 13 can be determined; however, mass balance tank 34'' is
not required. In one embodiment, there were no detectable amounts
of cobalt and nickel in the discharged raffinate 13 contained in
barren tank 30; however, small amounts of zinc were detected (e.g.
from about 78 ppm to about 163 ppm). In another embodiment shown in
FIG. 3, zinc levels may be reduced by sending the discharged
raffinate 13 for a third pass, in a down-flow direction through two
columns 158 which are arranged in parallel instead of sending the
discharged raffinate 13 directly to barren tank 30, a shown in FIG.
3 Two columns 158 are fluidically to the second set of columns 152
from which they receive an intake flow of the discharged raffinate
13; the two columns 158 are also fluidically connected to barren
tank 30 which receives the outflow of raffinate 13 from the two
columns 158.
[0046] As the ion exchange resin moves through the first and second
sets of columns 151, 152, it becomes more fully loaded with cobalt,
nickel and zinc to the point of equilibrium between the ion
exchange resin and raffinate 13, such that raffinate 13 is at full
strength (i.e., cobalt, nickel and zinc have not been removed).
Raffinate 13 at full strength needs to be displaced from the
cobalt/nickel/zinc removal ion exchange unit 15 to the first set of
columns 151. Two columns 153 may be used to achieve the
displacement. See FIGS. 2 and 3. The two columns 153 are
fluidically connected to cobalt/zinc eluate tank 28 to receive
cobalt/zinc eluate as an intake flow. Using cobalt/zinc eluate for
displacement, as opposed to water, for example, may result in
better cobalt recovery. Since the two columns 153 are loaded with
cobalt/zinc eluate when the eluting 113 of cobalt and zinc takes
place, without dilution from water, cobalt concentration is higher.
In addition, two columns 153 are fluidically connected to an inlet
end of the first set of columns 151 so that displaced raffinate 13
mixes with raffinate 13 from raffinate tank 12
[0047] After full loading of the columns with nickel, zinc and
cobalt, those metals are stripped by means of eluate system 23. In
addition to copper eluent tank 17, eluate system 23 comprises
cobalt/zinc eluent tank 27 and nickel eluent tank 26. Cobalt/zinc
eluent tank 28 and nickel eluent tank 29 are fluidically connected
to cobalt/nickel/zinc removal ion exchange unit 15 so that, at the
appropriate point, either cobalt/zinc eluent or nickel eluent can
be added to the cobalt/nickel/zinc removal ion exchange unit 15 to
strip either nickel or cobalt and zinc from the loaded resin. Since
cobalt does not adhere as strongly to the resin as nickel, cobalt
may be considered easier to remove than nickel, using an acid
concentration weaker than that required to strip the nickel.
Therefore, in the embodiments shown in FIGS. 2-4, cobalt and zinc
are removed first. Cobalt/zinc eluent tank 27 is sized for holding
cobalt/zinc eluent which comprises H.sub.2SO.sub.4 in concentration
of about 2% to about 4%, preferably between 2.5% to 3.85% ("weak
H.sub.2SO.sub.4"), although weak concentrations of other strong
acids may also be used. In the embodiment shown in FIGS. 2-4,
cobalt/zinc eluent comprises H.sub.2SO.sub.4 in concentration of
about 2% to about 3.5%. Cobalt/zinc eluent tank 27 is fluidically
connected to four columns 154 connected in series so that the
cobalt/zinc eluent enters each column within the four columns 154
at the bottom and exits at the top, as shown in FIGS. 2 and 3.
Cobalt and zinc are therefore eluted 113 (e.g., stripped) from the
bispicolylamine functionalized ion exchange resin in solution as
copper/zinc eluate. Cobalt/zinc eluate is conveyed to cobalt/zinc
eluate tank 28 which is fluidically connected with the last column
in the four columns 154 the last column in the four columns 154 is
also fluidically connected to mass balance tank 34''''. Mass
balance tank 34'''' allows cobalt/zinc eluate to be analyzed to
determine its composition; however, mass balance tank 34'''' is not
required.
[0048] Nickel is the next metal to be eluted 116; however, nickel
is to be eluted 116 with nickel eluent which is about 10 times
stronger than cobalt/zinc eluent (.about.20% v. .about.2%).
Therefore, just as the raffinate 13 at full strength needed to be
displaced from the cobalt/nickel/zinc removal ion exchange unit, so
does the cobalt/zinc eluent (weak H.sub.2SO.sub.4) need to be
displaced. Two columns 155 may be used to achieve the displacement.
See FIGS. 2 and 3. The two columns 155 are fluidically connected to
nickel eluate tank 28 in series to receive nickel eluate as an
intake flow. Using nickel eluate for displacement, as opposed to
water, for example, may result in better nickel recovery. Since the
two columns 155 are loaded with nickel eluate when the eluting 116
of nickel takes place, without dilution, nickel concentration may
be higher.
[0049] Nickel is next removed. Nickel eluent tank 26 is sized for
holding nickel eluent which comprises H.sub.2SO.sub.4 in
concentration of about 20% or 200 g/L, although other high
concentrations of strong acid could also be used. Nickel eluent
tank 26 is fluidically connected to three columns 156 connected in
series so that the nickel eluent enters each column within the
three columns 156 at the bottom and exits at the top, as shown in
FIGS. 2 and 3. Nickel is therefore eluted 116 (e.g., stripped) from
the bispicolylamine functionalized ion exchange resin in solution
as nickel eluate. Nickel eluate is conveyed to nickel eluate tank
29 which is fluidically connected with the last column in the three
columns 154; the last column in the three columns 154 is also
fluidically connected to mass balance tank 34''''. Mass balance
tank 34''' allows nickel eluate to be analyzed to determine its
composition; however, mass balance tank 34''' is not required.
[0050] After nickel is eluted 116, the nickel eluent in the three
columns 154 is displaced using nickel eluent rinse water. Nickel
eluent rinse water tank 36 is sized to hold nickel eluent rinse
water and is fluidically connected to three columns 157 in series
as shown in FIG. 2. Once the nickel eluent rinse water has
displaced the nickel eluent, the nickel eluent in recycled into the
eluate system 23. In another embodiment as shown in FIG. 4,
displacement of nickel eluent may be achieved by using discharged
raffinate 13 from barren tank 30. In that embodiment, nickel eluent
rinse water tank 36 is eliminated and the three columns 157 in
series are instead fluidically connected to barren tank 30.
[0051] In yet another embodiment of apparatus 10, the system for
eluting 116 nickel is a recycled system in which a single vessel
holds nickel eluent and nickel eluate. Nickel eluent/eluate tank 32
is sized to hold both nickel eluent and the nickel eluate produced
through the elution 116 of nickel in four columns 159. Nickel
eluent/eluate tank 32 is fluidically connected to the four columns
as shown in FIG. 3. Recirculation of the nickel eluate permits the
concentration of nickel to build up in the nickel eluate before
recovering the nickel or replacing the combined nickel
eluent/eluate solution.
[0052] Referring to FIGS. 5 and 6, method 100 for extracting cobalt
from raffinate 13 will now be described. Method 100 comprises
providing 101 a supply of raffinate 13. Providing 101 the supply of
raffinate may comprise adding raffinate 13 to process tank 14.
Since the embodiments of method 100 may depend on the constituents
in the raffinate 13, method 100 comprises analyzing 102 raffinate
13 to determine the composition of raffinate 13, including
identification of the metals and other elements present. In one
embodiment, raffinate 13 comprises cobalt, copper, iron and nickel.
Raffinate 13 also may include other metals, such as magnesium and
zinc. Variously, raffinate 13 analyzed 102 in accordance with
method 100 was determined to contain combinations of copper (about
125 to about 150 parts per million (ppm)), cobalt (about 50 to
about 55 ppm), nickel (about 40 to about 45 ppm), iron (about 500
to about 600 ppm total for ferric, ferrous or combined), magnesium
(about 7700 ppm) and zinc (about 300 ppm) at pH range from about
1.45 to about 1.8. See FIG. 4.
[0053] Method 100 further comprises selecting 103 at least one ion
exchange resin to separate out metals from raffinate 13. In an
embodiment of method 100, selecting 103 at least one ion exchange
resin comprises choosing a resin with high affinity for nickel and
cobalt, such as bispicolylamine. Given that bispicolylamine also
has high affinity for copper such that copper may load
preferentially, another ion exchange resin with high affinity for
copper, such as hydroxypropylpicolylamine functionalized resin, may
also be selected 103 so that copper can be removed from raffinate
13 before the raffinate 13 comes in contact with bispicolylamine
functionalized resin.
[0054] Method 100 may further comprise pretreating 105 raffinate
13. Selection 103 of various resins may have an effect on what kind
of pretreatment 105 steps may be necessary or advantageous, if any,
because the selected resins may perform more advantageously under
certain conditions. As discussed above, pretreating 105 raffinate
13 may comprise any or all of the steps of adjusting 104 (e.g.,
raising) the pH of raffinate 13, removing 106 any solids produced
as a result of the adjusting 104 process, or reducing 108 iron from
ferric iron to ferrous iron. In embodiments of method 100,
adjusting 104 (e.g., raising) the pH and reducing 108 ferric iron
are preferably undertaken prior to removing 100 substantially all
the copper in the ion exchange system 19, because copper catalyzes
iron reduction; therefore, it is more likely that iron would
reoxidize if the pH were adjusted 104 after removing 100
substantially all the copper. Pretreating 105 the raffinate may be
performed in process tank 14 or in other similar vessels.
[0055] Adjusting 104 the pH of raffinate 13 in embodiments of
method 100 comprises raising the pH of raffinate 13 to between
about 3.0 and about 3.7, preferably between about 3.0 and 3.5.
Depending on the metals present in the raffinate 13, as well as the
parameters of the ion exchange resin selected 103, other pH levels
may be preferred. In the embodiments described herein, raising the
pH level of raffinate 13 comprises adding CaO, CaCO.sub.3 or other
similar compound to raffinate 13 in process tank 14 in amounts
effective to raise the pH to between about 3.0 and about 3.7,
preferably between about 3.0 and 3.5; however, other chemical
reagents could also be used as would be familiar to one of ordinary
skill in the art after becoming familiar with the teachings of the
present invention. More specifically, in embodiments of the
invention, CaO may be added to raffinate 13 at a rate of about 2
grams per liter (g/L) to about 4 g/L; these amounts may vary
depending on whether a continuous feed process or batch process is
employed. Adjusting 104 the pH of raffinate 13 may further comprise
stirring raffinate 13 during and after addition of CaO, especially
where batch processes are employed.
[0056] Since raising the pH as just described tends to produce
solids (e.g., gypsum) that may clog ion exchange system 19, method
100 may further comprise removing 106 solids from raffinate 13.
Removing 106 solids may comprise using a variety of commercially
available coagulants and flocculents, such as Nalco N8850 coagulant
and N7871, which are added to process tank 14 following pH
adjustment, causing solids to form coagulated solids. Removing 106
solids may therefore further comprise filtering raffinate 13 to
remove coagulated and other solids, such as through drum filter 16
or other filtering or known physical separation methods. Removing
106 solids may further comprise additional filtering (e.g., with an
inline cartridge filter) prior to removing 110 substantially all
copper in the ion exchange system 19, as explained in more detail
below.
[0057] Given the varying affinities of bispicolylamine for ferric
iron (Fe III) and ferrous iron (Fe II) at low pH as shown in FIG.
8, pretreating 105 raffinate 13 according to method 100 further
comprises reducing 108 ferric iron to ferrous iron so that cobalt
will load the resin preferentially instead of iron. Reducing 108
ferric iron to ferrous iron comprises adding sodium sulfite
(Na.sub.2SO.sub.3) to raffinate 13 in an amount effective to reduce
all of the ferric iron to ferrous iron. Na.sub.2SO.sub.3 may be
added at a rate of 1 g/L of raffinate 13 in one embodiment. Of
course, if raffinate 13 contains only ferrous iron, no reducing 108
is necessary.
[0058] FIG. 7 also illustrates the high affinity that
bispicolylamine functionalized resin has for copper; thus, method
100 further comprises removing 110 substantially all copper from
raffinate 13. Removing 110 substantially all copper from raffinate
13 comprises using a first ion exchange resin selective to
copper.
[0059] The first ion exchange resin may comprise
hydroxypropylpicolylamine functionalized resin. Using the first ion
exchange resin preferably occurs prior to absorbing 112 cobalt and
nickel using a second ion exchange, such as bispicolylamine
functionalized resin. Otherwise, the second ion exchange resin will
bind preferentially to the copper, leaving no room for cobalt (and
nickel) to bind. Removing 110 substantially all copper from
raffinate 13 comprises feeding raffinate 13 (that has been
pretreated 105) through copper removal ion exchange unit 18 as
described herein in a manner that permits substantially all copper
to load the first ion exchange resin (e.g.,
hydroxypropylpicolylamine functionalized resin) contained in the
copper removal ion exchange unit 18. In an embodiment in which
copper removal ion exchange unit 18 comprises the fixed bed system
of multiple columns in lead lag configuration, raffinate 13 is
pumped into the top of the lead column 21 where it exits through
the bottom of the lead column 21 and is pumped into the top of lag
column 25, exiting lag column 25 free of substantially all copper.
Removing 110 substantially all copper from raffinate 13 comprises
stripping or eluting the copper from the first ion exchange resin
and regenerating the beds with copper eluent. Copper eluent may
comprise H.sub.2SO.sub.4 or lean electrolyte (containing copper and
strong acid, such as H.sub.2SO.sub.4). In one embodiment, copper
eluent is fed through the copper removal ion exchange system 18
countercurrent to the feed direction of raffinate 13. For example,
where raffinate 13 is fed in a down-flow direction, copper eluent
is fed in an up-flow direction. In one embodiment wherein copper
eluent comprises either H.sub.2SO.sub.4 or lean electrolyte,
raffinate 13 is displaced using 20% H.sub.2SO.sub.4 to regenerate
the beds; displacement may be done at a slower flow rate than the
rate used to load the beds with raffinate 13. In yet another
embodiment in which copper eluent comprises lean electrolyte, 20%
H.sub.2SO.sub.4 may be used to displace the lean electrolyte and
water may be used to displace the 20% H.sub.2SO.sub.4 prior to
loading the beds again with raffinate 13. In another embodiment,
water displacement may be employed before using copper eluent to
strip the copper.
[0060] The copper is recovered as CuSO.sub.4 and is of high purity
as shown in FIG. 8; thus, recovering 110 substantially all copper
in raffinate 13 further comprises conveying the copper in solution
to the EW tankhouse.
[0061] Once substantially all copper has been removed 110,
raffinate 13, minus the copper, is subjected to additional ion
exchange processes. Thus, method 100 comprises absorbing 112 cobalt
and nickel from raffinate 13 using the second ion exchange resin,
e.g. bispicolylamine functionalized resin. In an embodiment in
which raffinate 13 further comprises zinc, method 100 comprises
absorbing 111 cobalt, zinc and nickel using the second ion exchange
resin, e.g. bispicolylamine functionalized resin. Absorbing 111
cobalt, zinc and nickel may comprise supplying the columns with
raffinate 13 in a countercurrent direction, as described above.
[0062] Once the second ion exchange resin is fully loaded or
substantially fully loaded, method 100 may comprise eluting 114 the
cobalt from the second ion exchange resin, e.g., bispicolylamine
functionalized resin. Since cobalt does not adhere as strongly to
the second ion exchange resin as does nickel, cobalt may be
considered easier to remove than nickel, using an acid
concentration weaker than that required to strip nickel. Therefore,
in embodiments of method 100, eluting 114 the cobalt from the
second ion exchange resin comprises using cobalt eluent to strip
the cobalt from the second ion exchange resin. In one embodiment,
cobalt eluent comprises weak H.sub.2SO.sub.4 in concentration of
about 2% to about 4% by volume, preferably between 2.5% to 3.85% by
volume; however, other weak concentrations of other strong acid may
also be used. Eluting 114 cobalt further comprises removing cobalt
in solution after cobalt has been stripped from the second ion
exchange resin. Eluting cobalt 114 may further comprise displacing
120 cobalt eluent so that the second ion exchange resin may be
regenerated. Displacing 120 cobalt eluent may comprise using cobalt
eluate.
[0063] In another embodiment in which raffinate 13 further
comprises zinc, eluting 114 cobalt comprises co-eluting 113 cobalt
and zinc from the second ion exchange resin. Co-eluting 113 the
cobalt and zinc from the second ion exchange resin comprises using
cobalt/zinc eluent to strip the cobalt and zinc from the second ion
exchange resin. In one embodiment, cobalt/zinc eluent comprises
weak H.sub.2SO.sub.4 in concentration of about 2% to about 4%,
preferably between 2.5% to 3.85%; however, other weak
concentrations of strong acid may also be used. Cobalt/zinc eluent
may be the same substance as cobalt eluent. In an embodiment of
method 100, cobalt and zinc may remain combined in solution without
need for further separation. Co-eluting 113 cobalt and zinc may
further comprise displacing 122 cobalt/zinc eluent so that the
second ion exchange resin may be regenerated. Displacing 122
cobalt/zinc eluent may comprise using cobalt/zinc eluate.
[0064] In another embodiment, co-eluting 113 cobalt and zinc may
further comprise eluting cobalt 114 and eluting 118 zinc from the
copper/zinc eluate. In an embodiment, cobalt and zinc may be
separated by means of additional ion exchange processes using an
ion exchange resin that is more selective for zinc than for cobalt,
such as a resin containing aminophosphonic acid (APA) functional
groups as may be found in AMBERLITE IRC747 commercially available
from The Dow Chemical Company. APA-containing resins are selective
for zinc over cobalt.
[0065] In another embodiment, cobalt and zinc may be separated by
means of an anionic exchange resin, such a DOWEX 21K XLT. In that
embodiment, cobalt/zinc eluate may be treated with a salt, such as
sodium chloride (NaCl), although other salts could also be used.
Addition of a strong base anionic exchange resin may extract zinc
in its anionic form, leaving cobalt in solution.
[0066] After the cobalt has been eluted 114 or after the cobalt and
zinc have been co-eluted 113, method 100 comprises eluting 116
nickel using nickel eluent which comprises H.sub.2SO.sub.4 in
concentration of about 20% or 200 g/L; however, high concentrations
of other strong acids could also be used. Eluting 116 nickel may
further comprise displacing 124 nickel eluent so that the second
ion exchange resin may be regenerated. Displacing 124 nickel eluent
may comprise using nickel eluate. In another embodiment, eluting
116 nickel may comprise recycling nickel eluent so that the nickel
eluent becomes combined with the nickel eluate. The longer the
recycling continues, the higher the concentration of nickel eluate,
and therefore, the concentration of nickel in solution, than the
concentration of nickel eluent.
[0067] In order to provide further information regarding the
invention, the following examples are provided. The examples
presented below are representative only and are not intended to
limit the invention in any respect.
Examples 1-3
[0068] Examples 1-3 involved testing of laboratory samples of
raffinate 13.
[0069] In Example 1, raffinate 13 was made in the lab to test
copper recovery; the raffinate 13 comprised copper, ferric iron,
nickel, and magnesium sulfate at a pH of 1.72 to enhance copper
loading on the hydroxypropylpicolylamine resin. A column was
supplied with 20 milliliters (mL) resin and heated to approximately
50.degree. C. The raffinate was pumped through the column at 20 bed
volumes per hour (BV/hr). See FIG. 9. Iron and cobalt quickly broke
through the bottom of the column in concentrations higher than
their starting concentrations, indicating that the metals were
displaced from the resin by the more strongly held copper. Copper
eluted out of the resin between approximately 50 and 80 BV and
completed loading by 100 BV. The resin was regenerated and copper
eluted by rinsing the raffinate out of the resin in the column with
water and then pumping 20% H.sub.2SO.sub.4 through the column at 5
BV/hr. Copper was successfully eluted and was loaded to 16.3 g/L
resin. See FIG. 16.
[0070] In Example 2, raffinate 13 comprising ferric iron, nickel,
and magnesium sulfate, and no copper, was prepared in the lab in
order to test the recovery of cobalt and separation of cobalt from
iron. It was assumed that raffinate 13 had already had
substantially all copper removed 110. In Example 2, the pH of the
raffinate was adjusted to a level of 2.8 for the highest potential
of cobalt affinity for bispicolylamine resin. See FIG. 7. However,
iron precipitated at 2.8 pH and plugged the column so the testing
was stopped.
[0071] Example 3, raffinate 13 had the same composition as
raffinate 13 in Example 2. Na.sub.2SO.sub.3 was added to raffinate
13 to reduce ferric iron to ferrous iron. Following reduction,
raffinate 13 was pumped through a column of bispicolylamine
functionalized resin heated to 50.degree. C. at 20 BV/hr. Samples
were taken. Cobalt broke through the column at between about 120
and about 140 BV with full breakthrough by 180 BV. Nickel (green
band) and cobalt (red/pink band) could be seen as having loaded
onto the resin together, with nickel being bound more strongly to
the resin than cobalt. Cobalt and nickel were eluted in a two
stages to separate them. Since cobalt is not held to the resin as
firmly as nickel, cobalt can be removed with a weaker acid
solution; therefore, cobalt was eluted from the resin with 2%
H.sub.2SO.sub.4. Nickel was removed using 20% H.sub.2SO.sub.4. Some
iron eluted with the cobalt which may have resulted form possible
re-oxidation of iron, causing iron to reload on the column as
ferric iron. Example 3 showed 5.5 g/L of cobalt loading, 6.1 g/L of
nickel loading and 1.7 g/L of iron loading. See FIG. 10.
Examples 4-5
[0072] In Examples 4-5, raffinate 13 generated from copper SX at
ASARCO's Ray Mine, Hayden, Ariz. was used for testing copper and
cobalt removal.
[0073] In Examples 4-5, raffinate 13 was tested using the same
procedure for copper removal as in Example 1 for copper removal;
however, since the iron was ferrous iron, no reduction was
necessary. Multiple columns of bispicolylamine resin were placed in
series to utilize copper capacity on the lead column without having
copper breakthrough the bottom of the final column. In Example 4,
copper loading occurred at a pH of 1.87 and raffinate 13 was fed
through the columns at 20 BV/hr. Copper was stripped from the resin
using 20% H.sub.2SO.sub.4 at the slower flow rate of 5 BV/hr. See
FIG. 11.
[0074] In Example 5, the copper-free raffinate generated during
Example 4 was tested for cobalt removal using the same procedure
employed in Example 3. CaO was added to the copper-free raffinate
to achieve a pH of 3.39. Raffinate 13 was filtered to remove solids
(e.g., gypsum) and pumped through the resin to recover both cobalt
and nickel. Raffinate 13 was pumped through the columns for 90
BV/hr. Raffinate was removed from the columns with water. Cobalt
and nickel were selectively eluted using 2% H.sub.2SO.sub.4 to
strip the cobalt and 20% H.sub.2SO.sub.4 to strip the nickel. The
elution curve showed significant presence of zinc. See FIG. 12.
Example 6
[0075] In Example 6, cobalt removal was tested with lab-prepared
raffinate 13 comprising zinc, nickel, cobalt, ferrous iron and
magnesium sulfate, minus copper and ferric iron, assuming that the
steps of removing 110 substantially all copper and adjusting 104
the pH of raffinate 13 had already been completed. Raffinate 13 was
loaded on bispicolylamine resin. Raffinate 13 was rinsed from the
resin with water. A method for eluting cobalt, iron and nickel was
tested. A solution half saturated with sodium chloride (NaCl) was
passed through the resin to convert zinc to its anionic chloride
form. Hydrochloric acid (HCl) (1%) in half-saturated NaCl was used
to elute cobalt and iron (and some nickel) while keeping the
anionic zinc loaded on the resin. The resin, which has weak base
functionality, protonated in the strong acid solution, holding the
anionic zinc while eluting the cationic cobalt, nickel and iron.
Excess chloride was rinsed out of the resin with water, causing
zinc to convert back to its cationic form that was then absorbed
again by the chelating groups. 20% H.sub.2SO.sub.4 was used to
strip the zinc as well as the residual nickel that was not removed
with HCl. See FIG. 13.
Example 7
[0076] Example 7 concerned methods for pH adjustment and iron
reduction using raffinate 13 from the Ray Mine. Based on the
results in FIG. 8, it was determined that determined that both
steps may occur simultaneously prior to copper removal since copper
catalyzes the reduction of iron with sulfite.
Example 9
[0077] Cobalt was recovered using bispicolylamine resin at a pH of
2.8. These results demonstrated that cobalt will load on the resin
at a pH in a range of about 2.7 to about 3.5.
Example 10
[0078] In Example 10, raffinate 13 was pretreated with CaCO.sub.3
to adjust pH to 2.75 and with Na.sub.2SO.sub.3 to reduce iron and
was filtered. The resin was loaded with cobalt, nickel and zinc
from the pretreated raffinate at 20 BV/hr. Elution was done in two
steps. Cobalt and zinc were eluted first with 2% H.sub.2SO.sub.4;
nickel, with 20% H.sub.2SO.sub.4. The cobalt/zinc eluate had a
cobalt concentration of 1-2 g/L; zinc, a concentration of 2-5 g/L.
As a smaller stream, the raffinate 13 had a higher concentration of
both cobalt and zinc than previously observed. FIG. 14.
Example 11
[0079] The cobalt/zinc eluate (200 mL) from Example 10 was treated
with 1 molar (M) NaCl and passed through 25 mL of a strong base
anion exchange resin (e.g. DOWEX 21K XLT) to remove the anionic
zinc. Due to the small amounts involved, zinc was removed, but in
small quantities. It may be advantageous to use multiple and deeper
beds of resin in a series to obtain complete zinc removal. See FIG.
15.
Example 12
[0080] In Example 12, testing was done on raffinate from the Ray
Mine. A variety of tests were performed.
[0081] First, raffinate 13 was tested for organic removal. Because
raffinate 13 had a pH of 1.75 as shipped, and a pH of 3.0-3.5 after
pH adjustment as described herein, organic removal testing was
conducted at these two pH levels. Solids were present when pH was
adjusted to 3.4. Testing was performed with and without the solids
filtered out. An equilibrium isotherm test, or "bottle shake" test,
was performed to determine if organics could be removed from
pretreated raffinate. Adsorbent resin DOWEX OPIPORE L493 was used,
along with hydroxypropylpicolylamine resin and bispicolylamine
resin. The testing was performed at ambient temperature with 100 mL
of raffinate and 1 mL of resin with overnight shaking. Testing for
total organic carbon revealed that all three resins remove some
total organic carbon from raffinate 13 with better removal at lower
pH.
[0082] In a batch process using 400 gallon process tanks containing
raffinate 13, raffinate underwent pH adjustment 104 by adding 3 g/L
CaO; iron reduction 108, by adding 10 g/L Na.sub.2SO.sub.3; and
solid removal 106, by adding 5 ppm coagulant (N8850). The solution
was stirred overnight with a submersible circulation pump. Although
the target pH was 3.0 to 3.5, the next day, the pH measured 2.7.
The pH was adjusted with 1 g/L CaO and stirred for another day,
achieving a final pH or 3.7. With the pump on, flocculant (N7871)
was added, raffinate 13 was stirred, and then the pump was turned
off to settle overnight. Raffinate 13 was then pumped off the top
of the tank into a clean tote; the feed at the bottom of the tank
with the solids was pumped into a separate tote. The pH level was
adjusted further with 3.5 g/L CaO to within the desired range and
measured 3.4.
[0083] Prior to copper removal, an inline cartridge filter was used
to filter out any solids to minimized clogging of the resin beds.
Copper removal was tested with two fixed beds of
hydroxypropylpicolylamine resin. Each bed was 2 inches in diameter
and about 4.5 feet deep with about 3 L of resin in each in a
lead-lag configuration of columns. Raffinate was pumped into the
top of a first column, out the bottom of the first column, and
directly into the top of a second column from which it exited
copper free. Sample ports were used to collect samples of raffinate
coming out the bottom of each column. The lead (first) column 21
may then be regenerated with acid.
[0084] Breakthrough testing for copper removal using a freshly
regenerated lag bed and a partially copper loaded lead bed; it
showed that copper loaded well on the hydroxypropylpicolylamine
resin using two passes. When the lead bed was nearly completely
loaded with copper (100 BV), no copper could be detected breaking
through the lag bed; however, a light blue color through the column
indicated a small amount of copper breakthrough. See FIG. 16.
[0085] Regeneration of the lead bed with 20% H.sub.2SO.sub.4 was
done in a direction countercurrent to copper loading with raffinate
13 at a flow rate of 8 BV/hr. Raffinate 13 was loaded in a
down-flow direction and regeneration was performed in an up-flow
direction so that the resin was almost completely regenerated when
it was being fed with raffinate 13. Regeneration of the resin was
performed at a slower rate than the copper loading with raffinate
13 to maximize copper concentration. The majority of the copper
came off the resin in a single bed volume with a maximum
concentration of 25 g/L. The copper loading capacity on the resin
was determined to be about 12 g/L. This amount was lower than the
total capacity of the resin and very selective for the copper over
the other metals in the raffinate as shown in Table 1 below.
TABLE-US-00001 TABLE 1 Cu Fe Ni Co Zn Mn Loading 11.99 0.18 0.14
0.01 0.07 0.25 g/L Loading 94.86 1.42 1.11 0.08 0.55 1.98 Metal
%
The regeneration showed that 95% of the metal on the resin was
copper. In other embodiments, there may be more optimization with
feed displacement with water between the loading and the stripping
with acid, such as water displacement with 1 BV/hr. There were no
peaks noted for iron, cobalt, zinc or manganese; however, a small
amount of nickel was stripped, as shown in FIG. 17-18.
[0086] In one embodiment, copper eluent may comprise lean
electrolyte rather than clean acid. See, e.g., FIG. 19. Raffinate
13 in the column would need to be displaced with about 1 BV water
back to starting point to keep undesirable metals from
contaminating the copper. Copper would then be stripped from the
column with lean electrolyte and transported to the EW tankhouse.
Remaining lean electrolyte would strip a small amount of copper,
which can be held until the next regeneration and used as the first
amount of copper eluent. Fresh acid may be used to displace the
lean electrolyte and water may be used to displace the acid before
switching back to feed.
Example 13
[0087] In Example 13, cobalt/zinc removal and nickel removal
testing were done on raffinate 13 from the Ray Mine, using
apparatus 10 as shown in FIGS. 2-4.
[0088] Raffinate 13 that was pretreated 105 with pH adjustment 104,
iron reduction 108 and filtering, as well having substantially all
copper removed 110, was subjected to cobalt removal processes using
apparatus 10 previously described with reference to FIGS. 2-4. With
specific reference to FIG. 2, pretreated raffinate 13, with copper
removed, was conveyed from raffinate tank 12 (which, as shown, was
a 400-gallon tank) to cobalt/nickel/zinc ion exchange unit 15,
comprising a carousel equipped with 24 columns 151-159 loaded with
bispicolylamine functionalized resin, such as that which has
previously been described. The carousel was connected to a multiple
port valve and was set on a timer so that the column index rotated
regularly around the multiple port valve. Switchboards along the
side of the cobalt/nickel/zinc ion exchange unit 15 (e.g.,
carousel) allowed access to the top and bottom of each column and
allowed for the various solutions used during method 100 to be
supplied to the particular groups of columns at the appropriate
times. In one full rotation of the carousel, the bispicolylamine
functionalized resin was subjected to loading with raffinate 13,
rinsing, and eluting 113, 116. Raffinate 13 was pumped from the
raffinate tank 12 through the first set of columns 151, each in a
down-flow direction. The first set of columns 151 was arranged in
parallel so that raffinate 13 entered each column at the top
flowing through to the bottom. As shown in FIG. 2, the discharged
raffinate 13 from each of the first set of columns 151 was
collected and then pumped through the second set of five columns
152 arranged in a manner similar to the first set of five columns
151 so that the raffinate 13 entered each column at the top,
flowing to the bottom of each column in a down-flow direction. As
shown in FIGS. 2-4, the columns of the carousel moved in the first
direction (e.g., in a direction from right to left as indicated by
arrows 38); however, the raffinate 13 was fed into the first and
second sets of columns 151, 152 in the second direction
countercurrent to the direction of arrows 38 (e.g., left to right
as shown in FIGS. 2-4). It is believed that feeding raffinate 13 in
the second direction countercurrent to the first direction
increased efficiency of the bispicolylamine functionalized resin
with which the columns 151-159 were loaded.
[0089] Raffinate 13 discharged from the second set of columns 152
was collected and conveyed to barren tank 30. Some of the
discharged raffinate 13 was collected in mass balance tank 34'' so
that its composition could be analyzed. Mass balance analyses from
the several runs tested are listed below. In this test, it was
determined that since cobalt concentration limits were near the
detection limit of the x-ray fluorescence detector (XRF), loading
was optimized on the more concentrated zinc. Timing of the test was
based on the point at which the resin was fully loaded. For this
test, the timing between indexes was 21 minutes.
[0090] Moving through the first and second sets of columns 151,
152, the bispicolylamine functionalized resin became more fully
loaded with cobalt, nickel and zinc to the point of equilibrium
between the ion exchange resin and raffinate 13, such that
raffinate 13 was at full strength (e.g., cobalt, nickel and zinc
have not been removed). Raffinate 13 at full strength therefore
needed to be displaced back to the first set of columns 151. This
was accomplished using two columns 153 connected in series, as
shown in FIGS. 2-4. Cobalt/zinc eluate, which is this example
comprised 2% H.sub.2SO.sub.4, as well as already stripped cobalt
and zinc. The two columns 153 were connected to cobalt/zinc eluate
tank 28 so that the two columns 153 received cobalt/zinc eluate in
an up-flow direction from left to right countercurrent to the
direction of arrows 38, which is the direction in which the ion
exchange resin indexes, as shown in FIGS. 2-4. Cobalt/zinc eluate
was chosen to use for displacement rather than water to avoid
dilution so as to keep the cobalt concentration higher, because the
cobalt/zinc are already in the cobalt/zinc eluate. Again, it is
believed that the countercurrent relationship between the resin
indexing and the cobalt/zinc eluate flow increased the efficiency
of the process, reducing the amount of weak H.sub.2SO.sub.4
required.
[0091] The bispicolylamine functionalized resin was then stripped
with cobalt/zinc eluent comprising weak H.sub.2SO.sub.4.
Cobalt/zinc eluent was contained in cobalt/zinc eluent tank 27 that
was fluidically connected to the four columns 154 connected in
series so that the cobalt/zinc eluent entered the four columns 154
at the bottom and exited at the top, as shown in FIGS. 2-4. After
stripping in the four columns 154, cobalt and zinc were co-eluted
113 in cobalt/zinc eluate which was conveyed from the last column
of the four columns 154 to cobalt/zinc eluate tank 28. Mass balance
tank 34'''' allowed for the cobalt/zinc eluate to be analyzed.
[0092] Next, to prepare the system for eluting 116 nickel, the
cobalt/zinc eluent had to be displaced. Displacement was done with
nickel eluate comprising 20% H.sub.2SO.sub.4 plus stripped nickel
for the same reasons that cobalt/zinc eluate were used for
displacement as explained above. Nickel eluate was supplied from
nickel eluate tank 28 to two columns 155 connected in series, as
shown in FIGS. 2-4.
[0093] Nickel was eluted 116 next using nickel eluent, which was a
strong acid, 20% H.sub.2SO.sub.4. Nickel eluent, from nickel eluent
tank 26, was supplied to three columns 156 connected in series so
that the nickel eluent entered each column at the bottom and exited
at the top as shown in FIG. 2. After stripping in the three columns
156, nickel was eluted 116 in nickel eluate which was conveyed from
the last column of the three columns 156 to nickel eluate tank 29.
Mass balance tank 34''' allowed for the nickel eluate.
[0094] After the nickel was eluted 116, the nickel eluent in the
three columns 157 was displaced using nickel eluent rinse water
contained in nickel eluent rinse tank 36. Nickel eluent rinse tank
36 was connected to the three columns 156 arranged in series so
that the nickel eluent rinse water entered each column at the
bottom and exited at the top as shown in FIG. 2. The displaced
nickel eluent was fed back into the elution circuit to minimize
waste.
[0095] The system of Example 13 was run several times before
collecting composition data. After that several mass balance runs
were performed to analyze the composition of raffinate 13 entering
the system, and raffinate, as well as cobalt/zinc eluate and nickel
eluate, exiting at each point in the system. With additional
testing, cobalt concentration in the cobalt/zinc eluate continued
to increase, while nickel and iron concentrations were low. Nickel
stripped with the cobalt appeared to be related to the acid
strength of the cobalt/zinc eluent stripping acid strength, which
seemed to be best balanced under the operating conditions tested
where cobalt/zinc eluent comprised about 3.5% H.sub.2SO.sub.4.
[0096] Mass Balance 1
[0097] Upon start-up, cobalt/zinc eluate began traveling to the
left on the switchboard. Therefore, the flow rate of the
cobalt/zinc eluent was increased several times. The acid
concentration of the cobalt/zinc eluent was also checked and
increased. While the original concentration was 2.5%, this was
increased to 3.85% by adding more acid. The increase in
concentration provided better results. The iron loading was low;
however, iron re-oxidization may have occurred due to a
several-week interval between copper removal and this mass balance
test. In an embodiment, low iron loading may be remedied by further
lowering the pH of the raffinate 13 level to obtain better reducing
action from Na.sub.2SO.sub.3.
[0098] Results [0099] Mass Balance Tank 34'': Discharged
raffinate/barren looked good (XRF data) [0100] Co=0 ppm [0101] Ni=0
ppm [0102] Zn=22 ppm [0103] Fe=497 ppm (raffinate was 506 ppm)
[0104] Mass Balance Tank 34'''': Co/Zn eluate was slightly
contaminated [0105] Co=633 ppm [0106] Ni=396 ppm [0107] Zn=3378 ppm
[0108] Fe=531 ppm (raffinate was 506 ppm) [0109] Mass Balance Tank
34'''': Ni eluate contained only Ni (352 ppm) [0110] Overall metal
loading on the resin was lower than expected [0111] Co=1.91 g/L
[0112] Ni=1.72 g/L [0113] Zn=10.19 g/L [0114] Fe=1.60 g/L [0115]
Total=15.42 g/L [0116] Expected.about.20 g/L
[0117] Mass Balance 2
[0118] Following the Mass Balance 1 test, changes were made to
apparatus 10, as well as method 100. As shown in FIG. 4, nickel
eluent rinse water tank 36 was removed. Instead, a pump was added
so that displaced raffinate 13 from barren tank 30 could be used
for displacement. As shown in FIG. 4, barren tank 30 was then
connected to three columns 157 in series so that displaced
raffinate 13 from barren tank 30 could be pumped into each column
so that it entered at the bottom and exited at the top. After one
pass, it appeared that the resin was not fully loaded by the time
the resin exited the loading zone in the first and second set of
columns 151, 152. Therefore, three passes were used before moving
the columns to try to get the loading higher.
[0119] Results [0120] Mass Balance Tank 34'': Discharged
raffinate/barren contained more Zn after running loading zone
without indexing (XRF data) [0121] Co=0 ppm [0122] Ni=0 ppm [0123]
Zn=78 ppm [0124] Fe=544 ppm [0125] Mass Balance Tank 34'''': Co/Zn
eluate was cleaner [0126] Co=703 ppm [0127] Ni=353 ppm [0128]
Zn=2827 ppm [0129] Fe=350 ppm [0130] Mass Balance Tank 34''': Ni
Eluate contained Ni and Fe [0131] Ni=352 ppm [0132] Fe=31 ppm
[0133] Overall metal loading on the resin was lower than Mass
Balance 1, but cobalt loading was slightly higher [0134] Co=2.03
g/L [0135] Ni=1.47 g/L [0136] Zn=8.16 g/L [0137] Fe=1.05 g/L [0138]
Total=12.71 g/L
[0139] Mass Balance 3
[0140] Following Mass Balance 2, two changes were made to apparatus
10 and method 100 for Mass Balance 3. Because nickel concentration
in the nickel eluate was low with a lot of 20% H.sub.2SO.sub.4
containing a few ppm of nickel, nickel elution 116 was converted to
a re-circulation system to allow nickel concentration to build up
over time. When nickel concentration reaches a high level, the
entire nickel eluent/eluate could be replaced with fresh acid, or
some nickel eluent/eluate could be removed and replenished with
fresh acid to allow nickel to continue to be stripped. Thus, as
shown in FIG. 3, nickel eluent tank 26 and nickel eluate tank 29
were removed. In the spot previously occupied by nickel eluate tank
29, nickel eluent/eluate tank 32 was inserted to hold both the
nickel eluent and the nickel eluate which were recycled. However,
nickel eluent/eluate tank 32 was connected to four columns 159 as
shown in FIG. 3. Another change was made, this time to the loading
section. From previous tests, it appeared that metal was getting
through the loading section as evidenced by high zinc which may be
correlated with the presence of cobalt. As shown in FIG. 3, two
columns 158 were added to accommodate the discharged raffinate 13
from the second set of columns 152. The entire flow of discharged
raffinate 13 was fed through the two columns in parallel as shown
in FIG. 3. The result was not only to collect trace metal left in
the discharged raffinate 13, but also to displace any nickel
eluent/eluate left in the column. The same pump added in FIG. 4 to
pull discharged raffinate 13 from barren tank 30 for rinsing was
also used to balance the re-circulated regeneration of the nickel,
as well as weak acid displacement from the cobalt/zinc co-eluting
113 process.
[0141] Results [0142] Mass Balance Tank 34'': Discharged
raffinate/barren contained more Zn after running loading zone
without indexing (XRF data) [0143] Co=0 ppm [0144] Ni=0 ppm [0145]
Zn=107 ppm [0146] Fe=652 ppm [0147] Mass Balance Tank 34'''': Co/Zn
Eluate had higher Co [0148] Co=898 ppm [0149] Ni=530 ppm [0150]
Zn=3622 ppm [0151] Fe=362 ppm [0152] Mass Balance Tank 34''': Ni
eluate contained Ni and Fe [0153] Ni=468 ppm [0154] Fe=120 ppm
[0155] Overall metal loading on the resin was lower, but mostly due
to less Fe and Zn [0156] Co=1.76 g/L [0157] Ni=1.16 g/L [0158]
Zn=7.10 g/L [0159] Fe=0.69 g/L [0160] Total=10.72 g/L
[0161] Mass Balance 4
[0162] Mass balance 4 was conducted using apparatus 10 as shown in
FIG. 3. In previous tests, more iron appeared in the cobalt eluate
than expected. It was believed that iron may have resulted from
failure to displace all raffmate 13 in the column. Since manganese
does not load on the resin and was present in fairly high
concentration in raffinate 13, it was believed that manganese would
be a good marker for raffinate 13 in the cobalt eluate. To control
this, the pumps for the cobalt elution 114 and raffinate 13
recovery were better balanced. The raffmate recovery pump was
turned up to ensure no raffinate 13 made it into the cobalt eluate.
No raffinate 13 showed up in the cobalt eluate since manganese and
iron concentrations were 0 ppm. Since nickel appeared in the cobalt
eluate, the cobalt/zinc eluent was slightly diluted in an attempt
to strip less nickel at this step. The cobalt/zinc eluent acid
concentration was dropped from 3.85% to 3.37% H.sub.2SO.sub.4.
[0163] Results [0164] Mass Balance Tank 34'': Discharged
raffinate/barren (XRF data) [0165] Co=0 ppm [0166] Ni=0 ppm [0167]
Zn=96 ppm [0168] Fe=628 ppm [0169] Mn=836 ppm (838 ppm in the feed)
[0170] Mass Balance Tank 34'''': Co/Zn eluate had much higher Co
and no entrained raffinate [0171] Co=1616 ppm [0172] Ni=524 ppm
[0173] Zn=6640 ppm [0174] Fe=0 ppm [0175] Mn=0 ppm [0176] Mass
Balance Tank 34''': Ni eluate continued to increase in
concentration; Fe is near the detection limit [0177] Ni=932 ppm
[0178] Fe=0 ppm [0179] Overall metal loading on the resin was
similar [0180] Co=1.99 g/L [0181] Ni=0.93 g/L [0182] Zn=8.17 g/L
[0183] Fe=0 g/L [0184] Total=11.09 g/L
[0185] Mass Balance 5
[0186] In mass balance 5, cobalt concentration continued to
increase in the cobalt eluate, and the nickel concentration was
lower which may have been due to the lower acid concentration of
the cobalt/zinc eluent. Iron did load on the resin although there
was no raffinate entrained as shown by lack of manganese in the
cobalt eluate. Likely, this may have resulted from reoxidization of
the iron during intervals between tests.
[0187] Results [0188] Mass Balance Tank 34'': Discharged
raffinate/barren (XRF data unless noted) [0189] Co=6.42 ppm
(Raffinate Co=47.57; both numbers by AA) [0190] Ni=0 ppm [0191]
Zn=163 ppm [0192] Fe=596 ppm [0193] Mn=853 ppm [0194] Mass Balance
Tank 34'''': Co/Zn eluate had higher Co, but some Fe [0195] Co=2076
ppm [0196] Ni=216 ppm [0197] Zn=7373 ppm [0198] Fe=552 ppm [0199]
Mn=0 ppm [0200] Mass Balance Tank 34''': Ni Eluate continued to
increase in concentration; Fe is near the detection limit [0201]
Ni=1144 ppm [0202] Fe=38 ppm [0203] Overall metal loading on the
resin was lower [0204] Co=1.85 g/L [0205] Ni=0.23 g/L [0206]
Zn=6.53 g/L [0207] Fe=0.52 g/L [0208] Total=9.12 g/L
[0209] While only selected embodiments have been chosen to
illustrate the present invention, it will be apparent to those of
ordinary skill in the art from this disclosure that various changes
and modifications can be made herein without departing from the
scope of the invention as defined in the appended claims. For
example, the size, shape, location or orientation of the various
components disclosed herein can be changed as needed or desired.
Components that are directly connected may have intermediate
structures between them. The functions of two or more elements or
units may be performed by one and vice versa. The structures,
steps, and functions of one embodiment may be adopted in another
embodiment. It is not necessary for all advantages to be present in
a particular embodiment at the same time. In addition, terms of
degree such as "substantially," "about," and "approximate" as used
herein mean a reasonable amount of deviation of the modified term
such that the result would not be changed. For example, these terms
can be construed as including a deviation of at least .+-.5% of the
modified term if this deviation would not negate the meaning of the
term it modifies. Thus, it is contemplated that the inventive
concepts herein described may be variously otherwise embodied and
it is intended that the appended claims be construed to include
alternative embodiments of the invention, except insofar as limited
by the prior art.
* * * * *