U.S. patent application number 12/921020 was filed with the patent office on 2011-02-10 for process for metal seperation using resin-in-pulp or resin-in-solution processes.
This patent application is currently assigned to Fenix Hydromet Australasia Pty.Ltd.. Invention is credited to David Bruce Dreisinger, Charles Alexander MacDonald, David Richard Shaw.
Application Number | 20110030508 12/921020 |
Document ID | / |
Family ID | 41055472 |
Filed Date | 2011-02-10 |
United States Patent
Application |
20110030508 |
Kind Code |
A1 |
Dreisinger; David Bruce ; et
al. |
February 10, 2011 |
Process for Metal Seperation Using Resin-in-Pulp or
Resin-in-Solution Processes
Abstract
A process for the treatment of solutions or slurries containing
dissolved metals comprises the steps of (a) contacting the solution
or slurry with an ion exchange resin that selectively removes one
or more dissolved metals from the solution or slurry wherein the
solution or slurry and the resin are introduced into a vessel or
column via sub-surface means, (b) separating loaded resin from the
solution or slurry, (c) eluting the one or more metals from the
loaded resin with an eluting agent, (d) separating the eluting
solution containing eluted metal ions from the resin; and (e)
transferring regenerated resin from step (d) back to step (a).
Inventors: |
Dreisinger; David Bruce;
(Ladner, CA) ; MacDonald; Charles Alexander;
(Samsonvale, AU) ; Shaw; David Richard; (Benalla,
AU) |
Correspondence
Address: |
MARSHALL, GERSTEIN & BORUN LLP
233 SOUTH WACKER DRIVE, 6300 WILLIS TOWER
CHICAGO
IL
60606-6357
US
|
Assignee: |
Fenix Hydromet Australasia
Pty.Ltd.
Benalla, Victoria
AU
|
Family ID: |
41055472 |
Appl. No.: |
12/921020 |
Filed: |
February 26, 2009 |
PCT Filed: |
February 26, 2009 |
PCT NO: |
PCT/AU09/00221 |
371 Date: |
October 25, 2010 |
Current U.S.
Class: |
75/724 |
Current CPC
Class: |
C22B 3/44 20130101; B01J
47/15 20170101; B01J 41/04 20130101; C22B 3/42 20130101; C22B
15/0089 20130101; Y02P 10/234 20151101; C22B 3/24 20130101; C22B
23/0461 20130101; B01J 39/04 20130101; Y02P 10/236 20151101; Y02P
10/20 20151101; B01J 49/05 20170101; C22B 3/02 20130101 |
Class at
Publication: |
75/724 |
International
Class: |
C22B 3/24 20060101
C22B003/24 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 3, 2008 |
AU |
2008901030 |
Claims
1. A process for the treatment of solutions or slurries containing
dissolved metals comprising the steps of: a) contacting the
solution or slurry with an ion exchange resin that selectively
removes one or more dissolved metals from the solution or slurry,
said contacting comprising introducing the solution or slurry and
the resin into a vessel or column, wherein the resin is introduced
into the vessel or column via sub-surface means, b) separating
loaded resin from the solution or slurry; c) eluting the one or
more metals from the loaded resin with an eluting agent; d)
separating the eluting solution containing eluted metal ions from
the resin; and e) transferring regenerated resin from step (d) back
to step (a).
2. A process as claimed in claim 1 further comprising washing the
loaded resin to remove entrained solids, solution or slurry prior
to step (c);
3. A process as claimed in claim 1 wherein the slurry or solution
is subjected to a pre-treatment that removes oversize particles and
other contaminants therefrom prior to contacting or mixing the
slurry or solution with the resin.
4. A process as claimed in claim 3 wherein the pre-treatment step
comprises screening, settling, sedimentation, clarification,
separation using hydrocyclones, or centrifuging.
5. A process as claimed in claim 1 wherein a low speed or a low
shear mechanical mixer is used to mix the resin with the solution
or slurry.
6. A process as claimed in claim 5 wherein the low speed mechanical
mixer has an agitator operated such that a tip speed of the
agitator is less than 4.0 m/sec.
7. A process as claimed in claim 6 wherein the tip speed of the
agitator is less than 3.8 m/sec.
8. A process as claimed in claim 1 wherein the solutions or
slurries are treated by addition of one or more reagents to adjust
pH of the solutions or slurries to ensure that the target metal(s)
remain in solution while at the same time ensuring that the ion
exchange resin is operating within its optimal pH range for metal
uptake and to remove potentially interfering non-target soluble
metal ions by in-situ precipitation, wherein precipitation of the
non-target soluble metal ions occurs in a vessel in which step (a)
takes place.
9. A process as claimed in claim 8 wherein the non-target soluble
metal comprises ferric ions and the process comprises adjusting the
pH in step (a) to a value in the range of about 2.8 to 3.8.
10. A process as claimed in claim 8 wherein pH adjustment is
achieved by adding a solid neutralising agent to the solution or
slurry and the solid neutralising agent is screened to remove
oversize particles having a particle size greater than a
predetermined size prior to mixing with the ion exchange resin.
11. A process as claimed in claim 8 wherein pH adjustment is
achieved by adding a solid neutralising agent to the solution or
slurry and the solid neutralising agent is treated to remove
oversize particles having a particle size greater than a
predetermined size prior to mixing with the solution or slurry.
12. A process as claimed in claim 1 wherein the particle size of
the resin has a narrow size range.
13. A process as claimed in claim 1 wherein soluble iron removal
from the solution or slurry is required and is achieved by pH
adjustment and ferrous iron is oxidised to the ferric state in
order to induce precipitation of the soluble iron, wherein an
air/slurry contactor system is provided to facilitate oxidation of
ferrous iron to the ferric state.
14. A process as claimed in claim 1 wherein subsequent to resin
contact with the solution and/or slurry, the loaded resin is
separated from the treated solution and/or pulp in step (b) by use
of one or more screens.
15. A process as claimed in claim 1 wherein transfer of the resin
is achieved using dense phase hydraulic conveying.
16. A process as claimed in claim 1 wherein transfer of the resin
is achieved using water eduction, low shear recessed impellers, or
peristaltic pumps.
17. A process as claimed in claim 1 wherein the percentage of resin
solids in the solution or slurry is below 50%.
18. A process as claimed in claim 17 wherein the percentage of
resin solids in the solution or slurry is below 40%.
19. A process as claimed in claim 1 wherein the resin is
transferred in water and the process further comprises recovering
or recycling the water in a closed or partially closed loop.
20. A process as claimed in claim 1 wherein washing and/or elution
is conducted such that there is an upflow of water or solution
which causes fluidisation or entrainment of the resin in the
upflowing liquid.
21. A process as claimed in claim 20 wherein the resin overflows
from a process vessel over a screen to effect separation of the
resin from the liquid.
22. A process as claimed in claim 20 wherein transfer of the resin
to a next stage in the process occurs without passing the resin
through a pump or pumps.
Description
BACKGROUND TO THE INVENTION
[0001] The present invention relates to a process for metal
separation using resin-in-pulp (RIP) or resin-in-solution (RIS)
processes.
BACKGROUND TO THE INVENTION
[0002] A number of mining and downstream processing technologies
applied to run of mine ores result in the formation of soluble
metal containing solutions and pulps (slurries). Some of these
solutions or pulps arise from intentional processes (such as
leaching and other mineral processing and hydrometallurgical
processing technologies) while others may arise from water run-off
from tailings dams, waste rock dumps and the like, and may
accumulate in abandoned mining pits or be discharged into the
surrounding environment.
[0003] Solutions and slurries produced by leaching or other
hydrometallurgical processes typically contain one or more soluble
valuable metals (in the form of dissolved metal ions), together
with one or more soluble impurity components. A number of processes
are available to separate and recover the valuable metals. These
include precipitation, solvent extraction, adsorption and use of
ion exchange resins. In the case of ion exchange resins, it is
possible to use clarified solutions (known as resin-in-solution) or
to directly treat the pulp or slurry (known as resin-in-pulp).
[0004] Other solutions containing dissolved metal ions may be
formed due to acid mine drainage or acid rock drainage. These
solutions represent a significant source of environmental damage
and degradation.
[0005] In general, ion exchange processes (such as resin-in-pulp
and resin-in-solution processes) are best applied to solutions and
slurries that have relatively low soluble metal concentrations
and/or contain soluble metals that have a high intrinsic value.
Examples of such metals having a high intrinsic value include gold,
uranium and platinum group metals. For example, resin-in-pulp and
resin-in-solution processes are frequently used in the processing
of gold ores and uranium ores.
[0006] Resin-in-pulp and resin-in-solution processes are not
normally used for the treatment or recovery of base metals. In the
recovery of base metals, the concentration of the dissolved metal
is normally much higher than would be experienced in the recovery
of gold or uranium. Due to the high concentration of dissolved
valuable metal, the ion exchange resin has to undergo much more
frequent cycling through loading with the desired metal ions and
regeneration by removing or stripping the metal ions from the
resin. More frequent cycling of the resin normally results in more
rapid attrition or breakdown of the resin. This, in turn, leads to
increased costs for fresh or replacement resin.
[0007] It will be appreciated that there are a number of processing
challenges in a commercial application of ion exchange technology.
First and foremost, the solid resin needs to be physically
transferred in a manner that optimises its efficiency and
selectivity for metal removal/recovery and in a manner that
minimises the physical and chemical degradation of the solid ion
exchange resin through various means such as attrition and/or
osmotic shock. This applies to each of the three major steps
involved in ion exchange processes, namely loading (in which the
resin becomes loaded with the valuable metal by contacting fresh or
regenerated resin with the solution or pulp containing the
dissolved valuable metal), washing (in which excess or adherent
solution or slurry is washed from the resin) and elution (in which
the resin is contacted with a solution that removes the valuable
metal from the resin to thereby regenerate the resin and recover
the valuable metal into a more concentrated stream that contains
less impurities).
[0008] Excessive resin attrition can represent a significant
operating cost through the need to regularly replace the resin. In
addition, metal losses are associated with broken resin beads that
are subsequently lost from the processing circuit.
[0009] Throughout the specification, the term "comprising" and its
grammatical equivalents should be taken to have an inclusive
meaning unless the context of use indicates otherwise.
[0010] The applicant does not concede that the prior art discussed
in the specification forms part of the common general knowledge in
Australia or elsewhere.
BRIEF DESCRIPTION OF THE INVENTION
[0011] In a first aspect, the present invention provides a process
for the treatment of solutions or slurries containing dissolved
metals comprising the steps of:
[0012] a) contacting the solution or slurry with an ion exchange
resin that selectively removes one or more dissolved metals from
the solution or slurry, said contacting comprising introducing the
solution or slurry and the resin into a vessel or column, wherein
the resin is introduced into the vessel or column via sub-surface
means,
[0013] b) separating loaded resin from the solution or slurry;
[0014] c) eluting the one or more metals from the loaded resin with
an eluting agent;
[0015] d) separating the eluting solution containing eluted metal
ions from the resin; and
[0016] e) transferring regenerated resin from step (d) back to step
(a).
[0017] In some embodiments, the process further comprises washing
the loaded resin to remove entrained solids, solution or slurry
prior to step (c);
[0018] In the process of the present invention, step (a) results in
the resin being introduced into the vessel or column below the
surface of the solution or slurry in the vessel or column. This is
advantageous in that it assists in mixing and contacting the resin
with the solution or slurry. Further, the amount of agitation
required to mix the resin with the solution or slurry is minimised
which, in turn, minimises attrition of the resin caused by such
mixing.
[0019] When working with slurries having a high solids content or
working with slurries or solutions having a high viscosity, there
is a tendency for resins to float on the surface of the slurry or
solution. Utilising sub-surface introduction of the resin also
tends to overcome this problem, which again minimises the amount of
agitation required to mix the resin with the slurry or
solution.
[0020] In some embodiments of the present invention, the slurry or
solution may be subjected to a pre-treatment that removes oversize
particles and other contaminants therefrom prior to contacting or
mixing the slurry or solution with the resin. The pre-treatment
step may comprise any known treatment step that can remove
oversized particles from slurries or solutions. Examples include
screening, settling, sedimentation, clarification, hydrocyclones,
centrifuging and the like. It is envisaged that pre-screening is
the likely treatment to be used in commercial applications of such
embodiments of the present invention, but other pre-treatment steps
also fall within the scope of the present invention.
[0021] The pre-treatment step to remove any oversized particles and
other contaminants stops oversize particles and other contaminants
from accumulating in the process circuit. Furthermore, oversize
particles and other contaminants tend to increase the attrition of
resin particles as the oversize particles may act like grinding
media. Therefore, removal of oversize particles and other
contaminants will act to minimise attrition of the resin
particles.
[0022] The mixing of resins with pulps has historically been
achieved by means of air mixers, such as air mixed pachucas. Whilst
physical attrition of the resin beads may generally be at an
acceptably low level, the operating costs associated with provision
of the air supply are often unsustainable in economic terms. The
present inventors have found that mechanically agitated mixers may
be used in embodiments of the present invention. However, it is
preferred that particular attention be paid to the design of the
agitators and in particular, it is desired that the maximum tip
speed of the mixing blades be sufficiently low that physical
attrition of the resin beads is minimised. Accordingly, in
embodiments of the present invention, it is preferred that low
speed and/or low shear mechanical mixers be used to mix the resin
with the solution or slurry. The desired tip speed of the agitators
will depend somewhat on the strength and attrition resistance of
the resin being used. The agitator design and tip speed are
desirably controlled such that a balance between avoidance of
"sanding out" (which results in the heavier particles in the pulp
settling out) and excessive agitation of the resin is achieved. In
some embodiments, with the tip speed of the agitator may be less
than 4.0 m/sec, more preferably less than 3.8 m/sec.
[0023] In some embodiments of the present invention, pulps and
solutions to be treated may require the addition of specific
reagents to adjust the pH of the solution/pulp to ensure that the
target metal(s) remain in solution while at the same time ensuring
that the ion exchange resin is operating within its optimal pH
range for metal uptake. In addition, it may be appropriate to
adjust the operating pH to remove potentially interfering
non-target soluble metal ions by in-situ precipitation. A typical
example is the removal of soluble ferric ions by increasing the pH
of the solution/pulp to a value typically in the range of about 2.8
to 3.8.
[0024] In those cases where efficient separation and recovery of
valuable metals requires oxidation of ferrous iron and subsequent
precipitation of ferric iron by adjustment (neutralisation) of the
pH, the normal practice has been for this step to be carried out
prior to introduction of the solution and/or slurry to the ion
exchange circuit. The present inventors have discovered, however,
that this overall step can be conducted within the ion exchange
circuit itself in embodiments of the present invention. In other
words, in these embodiments, the inventors have found it
unnecessary to incorporate a separate oxidation/precipitation step
ahead of the ion exchange circuit. This results in considerable
capital and operating cost benefits.
[0025] In embodiments which require the addition of reagents to
modify the pH to the optimum range, which typically involves
addition of a neutralising agent, addition of the neutralising
agent generally causes solids to form in the solution and/or
increase the percentage of solids when using the RIP mode of
operation. Where limestone or other solid neutralising agent is
used as the acid neutralising agent, it is preferable to screen out
any oversize particles before the pH adjusted solution or pulp is
forwarded to the ion exchange circuit. If this oversize material is
not removed by this pre-screening step then there may be problems
encountered with the resin screening process itself.
[0026] Indeed, embodiments of the present invention that include
the addition of solid reagents or solid reactants to the process
may further include a step of treating, such as screening, the
solid reagent or solid reactants to remove oversized material
therefrom prior to mixing the reagents or reactants with the
solution or slurry.
[0027] The present invention encompasses the use of a wide variety
of resins. As will be appreciated by the person skilled in the art,
selection of resins takes into account both the chemical and
physical performance of the resin. The resin will typically show
selectivity for removing the desired metal ion from solution. The
resin will also desirably have mechanical properties that limit or
minimise attrition of the resin. In some instances, the mechanical
strength of the resin may be increased during manufacture of the
resin. In some instances, this may adversely impact on the chemical
performance or selectivity of the resin.
[0028] The selectivity, loading capacity and elution
characteristics of the resin may be tailored to the type and
concentration of both the soluble value and the soluble non-value
constituents of the solution and/or slurry being processed. In some
instances the selectivity of the resin is simply controlled by the
operating pH so that it is possible to separate out the desired
metal(s) by a relatively simple pH control procedure. In some
instances it may be preferable to use a resin that selectively and
irreversibly loads a non-value impurity component ahead of the main
ion exchange circuit where the soluble value metals are separated
and ultimately recovered.
[0029] The particle size of the resin may suitably have a narrow
size range. This is desirable as it allows for efficient separation
of the resin from the solution or pulp or slurry.
[0030] In embodiments where soluble iron removal is required and
achieved by pH adjustment it may be necessary to oxidise any
ferrous iron to the ferric state in order to induce precipitation
of the soluble iron. In such cases, mechanically agitated mixers
may be supplemented with a suitable air/slurry contactor system to
facilitate the oxidation of ferrous iron to the ferric state.
[0031] Subsequent to resin contact with the screened solution
and/or pulp that represents the metal loading stage, in some
embodiments, the loaded resin is separated from the treated
solution and/or pulp by use of one or more screens. The selection
of the optimum resin sizing and resin particle size distribution
may be such as to maximise recovery of the loaded resin while at
the same time minimising the energy and water washing requirements.
If the resin screen size is too large, excessive amounts of loaded
resin are lost out of the circuit. If the resin screen size is too
small, excessive amount of solids will be recovered along with the
loaded resin, leading to a much high level of water washing being
required.
[0032] In embodiments of the present invention, transfer of the
resin may be achieved using dense phase hydraulic conveying. One
example of a suitable dense phase hydraulic conveying process is
described in European patent number 0129999, the entire contents of
which are here incorporated by cross reference.
[0033] In other embodiments, transfer of the resin may be achieved
using water eduction, low shear recessed impellers, or peristaltic
pumps.
[0034] The selection of the transfer method may depend upon the
volume of resin required to be transferred. It may be desirable to
keep the percentage of resin solids in the solution or pulp below
50%, or even below 40%, in order to minimise attrition during
transfer. However, many resin in pulp systems face water balance
issues and consequently resin transfer using large volumes of water
is undesirable. However, transferring the resins using large
volumes of water and recovering or recycling the water in a closed
or partially closed loop enables the resin to be transferred as a
relatively low percentage solids slurry without impacting on the
water balance of the main processing plant.
[0035] In some embodiments of the present invention, various steps
in the process, such as washing and/or elution, may be conducted
such that there is an upflow of water or solution which causes
fluidisation or entrainment of the resin in the upflowing liquid.
This allows the resin to overflow from a process vessel over a
screen to effect separation of the resin from the liquid. This also
allows transfer of the resin to the next stage in the process
without necessarily having to pass through a pump or pumps, which
further minimises attrition of the resin. However, in some
embodiments, it may be necessary to use pumps to transfer the
resin. Alternatively, water eduction may be used to transfer the
resin.
BRIEF DESCRIPTION OF THE DRAWING
[0036] FIG. 1 shows a process flow sheet of an embodiment of the
present invention;
[0037] FIG. 2 shows a flow sheet of a single resin type, split
elution circuit in accordance with an embodiment of the present
invention; and
[0038] FIG. 3 shows a flow sheet of a two resins, split elution
circuit in accordance with an embodiment of the present
invention.
DETAILED DESCRIPTION OF THE DRAWING
[0039] The following description of a presently preferred but
non-limiting embodiment of the invention refers to the overall
process outlined in FIG. 1. For convenience, this Figure is of a
generic nature and all those skilled in the art will understand and
acknowledge that there are a number of variations possible that
comply with the overall concept of the invention. For example and
for convenience purposes only, FIG. 1 is limited to the treatment
and recovery of a single target metal by means of a single resin
and a single elution stage with a single eluant.
[0040] The metal-bearing solution or slurry [1] is pumped by
conventional means [2] to a pre-screening stage [3] where any
oversize material is removed as waste [4]. Optionally, a suitable
neutralising/pH control reagent [5] which may or may not be
supplemented by air sparging to induce oxidation of ferrous iron to
the ferric state, may be added directly to the metal-bearing
solution or slurry [1] and/or as the metal-bearing solution or
slurry is pumped to the pre-screening stage [2] and/or at the
pre-screening stage [3] and/or as the pre-screened metal bearing
solution or slurry is conveyed to the RIS/RIP circuit [10] and/or
at the RIS/RIP circuit [7].
[0041] Recycled resin [6] is added to the RIS/RIP circuit [7] by
means of a wet dense phase conveying system [8] together with any
resin make-up requirement [9], the pre-screened and optionally pH
adjusted feed solution or slurry [10], and any neutralising/pH
control reagent [5] required to maximise loading of the target
metal onto the selected resin. Mixing of the resin with the
incoming solution or slurry and any neutralising/pH control reagent
is achieved via mechanical methods supplemented by air sparging for
oxidation of ferrous iron to the ferrous state if required.
[0042] The RIS/RIP circuit [7] may be designed and operated in
conventional sequential column, fluidised bed or carousel modes,
the choice depending to a large extent on volume flows, loading and
eluting kinetics, and solids densities.
[0043] Following completion of the loading cycle, the metal-loaded
resin and the depleted solution or pulp [11] are transferred to the
loaded resin screening stage [12]. The screened loaded resin [13]
is transferred by means of the wet dense phase conveying system [8]
to the resin washing stage [14] and then to the resin elution stage
[13] where the loaded, washed resin is contacted with the
appropriate eluent [15]. The metal-rich eluate [16] is forwarded to
the metal recovery circuit [17].
[0044] The eluted, metal-free resin [18] is transferred by means of
wet dense phase conveyance system [8] to the resin transfer system
[6] for ultimate transfer to the RIS/RIP circuit [7].
[0045] The metal-depleted solution or pulp [19] exiting the loaded
resin screening stage [12] is treated by a combination of steps
[20] for the safe disposal of all solids and solutions and
comprises of appropriate neutralisation and solid/liquid separation
stages.
[0046] FIG. 2 shows a flow sheet of a single resin type, split
elution circuit in accordance with an embodiment of the present
invention. In the embodiment shown in FIG. 2, a leach liquor
containing dissolved metals (for example, containing dissolved
copper, nickel and cobalt) is fed via line 100 to the first of a
series of contacting vessels in which the leach liquor is contacted
with a resin. These contacting vessels are denoted by reference
numerals 102, 104, 106, 108, 110 and 112. The resin and liquor are
contacted with each other in counter current flow.
[0047] In the embodiments shown in FIG. 2, the contacting circuit
is effectively divided into two stages. The first stage includes
vessels 102, 104 and 106. Regenerated resin from first elution
column 114 is fed to contacting vessel 106 via line 116. The resin
is transferred from the vessel 106 to vessel 104 via dense phase
hydraulic conveying apparatus 118. Similarly, the resin is
transferred from vessel 104 to vessel 102 by dense phase hydraulic
conveying apparatus 120. Further, the resin from vessel 102 is
transferred to the elution column 114 via dense phase hydraulic
conveying apparatus 122. Use of dense phase hydraulic conveying
apparatus to transfer the resin assists in minimising attrition of
the resin.
[0048] The leach liquor 100 is initially fed to vessel 102. Liquor
overflow from vessel 102 is transferred to vessel 104. Similarly,
liquor overflow from vessel 104 is transferred to vessel 106.
[0049] A neutralising agent, such as a limestone slurry, is fed to
respective vessels 102, 104, 106 by respective lines 124, 126, 128.
Each vessel 102, 104, 106 is also provided with a low speed and/or
low shear agitator 130, 132, 134, respectively. The agitators
ensure good mixing and contact between the liquor and the resin
whilst also maintaining the pulp in suspension. At the same time,
due to the design and speed of the agitators, attrition of the
resin is minimised.
[0050] The loaded resin leaving vessel 102 is transferred via line
103 to the first elution column 114. In this column, acid 136 is
mixed with the resin to selectively elute the metal loaded onto the
resin. In the example given in FIG. 2, copper is loaded onto the
resin in vessels 102, 104, 106 by controlling the pH to between 2.5
and 3.5 and utilising a resin that selectively takes up copper from
solution in that pH range.
[0051] By virtue of the operating conditions in vessels 102, 104,
106, the liquor 138 leaving vessel 106 is depleted in copper but
still contains nickel and cobalt. Liquor 138 is fed to vessel 108
and thereafter to vessels 110 and 112. Resin (either regenerated or
fresh resin) is fed via line 140 to vessel 112 and thereafter by
respective dense phase hydraulic conveying apparatus 144, 146
(respectively) to vessel 110 and then to vessel 108. Loaded resin
is transferred via dense phase conveying apparatus 148 to second
elution column 150.
[0052] A neutralising agent, such as a limestone slurry, is fed via
respective lines 152, 154, 156 to each of the vessels 108, 110,
112, respectively. The pH conditions in vessels 108, 110, 112 are
such that nickel and cobalt are selectively taken up by the resin.
For example, the pH may be controlled to fall within the range of
3.5 to 4.5. Thus, the loaded resin that is fed via line 158 to
second elution column 150 is loaded with copper and nickel. The
elution conditions in elution column 150 are such that nickel and
cobalt are edited from the resin.
[0053] FIG. 3 shows a flow sheet of a two resins--split elution
circuit. In FIG. 3, an acidic leach liquor 200 containing dissolved
copper, nickel and cobalt is fed to the first stage of a metals
recovery circuit. The first stage comprises contacting vessels 202,
204, 206 and 208. In each of these vessels, a first resin is
contacted in counter current fashion using similar dense phase
hydraulic conveying apparatus as described with reference to FIG.
2. For brevity of description, this need not be described further.
Similarly, the liquor overflows each upstream vessel into a
downstream vessel in a manner similar to that described with
reference to FIG. 2. Again, for brevity of description, this need
not be described further. Low speed agitators are provided in each
vessel to maintain the slurry in suspension and to minimise
attrition. A neutralising agent is fed to each vessel via
respective lines 210, 212, 214, 216.
[0054] In the first stage, a resin that selectively removes one of
the metals in solution is used. For example, iminodiacetic resin,
which shows a good uptake of copper, a reasonable uptake of nickel
and a poor uptake of cobalt may be used, with the pH conditions in
the first stage being such that copper is selectively taken up by
the resin. Thus, the loaded resin provided via line 218 to elution
column 220 is loaded with copper. Acid supplied via line 222 is
used to elute the copper from the resin and to regenerate the
resin.
[0055] The liquor 224, that is depleted in copper, is fed to the
second part of the process, which comprises contacting vessels 230,
232. In the second part, a resin that shows a good uptake of nickel
and copper is used to remove the nickel and copper from the
liquor.
[0056] Again, dense phase hydraulic conveying is used to transfer
the resin. Again, low speed agitators that minimise attrition of
the resin are used. Again, a neutralising agent is fed to the
respective vessels in the second part via lines 226, 228.
[0057] The resin that is used in the second stage of the process
may comprise bospicolyamine resin. This resin exhibits a very
strong uptake of copper (indeed, so strong that copper is difficult
to remove from this resin). However, in the process shown in FIG.
3, copper has been removed in the first stage of the process. This
resin also shows a good uptake of nickel and cobalt, thus making it
suitable for use in removing those metals from solution in the
second stage. This resin is an expensive resin. Therefore, it is
used for residual nickel and cobalt recovery after copper has been
selectively removed from the liquor in the first stage of the
process.
[0058] The loaded resin from vessel 230 is fed via line 234 to
elution column 236. In elution column 236, the loaded resin is
contacted with acid 238 to cause elution of the nickel and cobalt
from the resin and to form a regenerated resin. The regenerated
resin is transferred via line 240 back to vessel 232.
[0059] Although not shown in either FIG. 2 or FIG. 3, makeup resin
may be provided in order to maintain resin balance in light of
losses of resin.
[0060] The eluted metal streams may be treated to recover metal
therefrom using any process is known to be suitable for that
use.
[0061] In some embodiments of the present invention, the following
advantages may arise: [0062] enhanced efficiency of the RIP and RIS
processes by means of improved design and operating procedures
involved in the contacting, transfer, handling and elution of the
resins. [0063] enhanced efficiency of the RIP and RIS processes by
means of the use of specific designs and types of pump suitable for
resin transfer to minimise resin attrition, as described herein
above. [0064] enhanced efficiency of the RIP and RIS processes by
means of the use of specific designs, types and speed of
agitators/mixers required for efficient mixing and suspension of
the resin while minimising resin attrition, as described herein
above. [0065] enhanced efficiency of the RIP and RIS processes by
means of the use of specific designs of air mixing of the resin
with the pulp or solution that also assists in the oxidation of
ferrous iron to the ferric state where it is required or desirable
to remove iron in conjunction with pH control. For example, many
processing circuits, such as base metals tails neutralisation,
contain residual metal values. In the case of acidic pulp tails, a
significant portion of iron is also typically present. Iron can be
precipitated from solution as either ferric (Fe.sup.3+) or ferrous
(Fe.sup.2+) hydroxide. Ferrous hydroxide does not form a dense,
easy to settle/dewater solid precipitate and therefore acidic tail
solutions being neutralised are frequently aerated using air or
oxygen sparging to convert ferrous to ferric and preferentially
precipitate ferric hydroxides. pH control is also used to assist in
achieving precipitation of ferric hydroxides. Air mixing resin in
circuits causes less attrition compared with mechanical agitation
but air mixing is an expensive operating cost and most plants now
use mechanical mixing rather than air mixing. However, in
embodiments of the present invention where it is designed to
convert ferrous to ferric as part of the process, the present
invention envisages that the air sparging and design of the
contactor can be modified to achieve both duties, i.e. ferrous to
ferric conversion and air mixing of the resin with the pulp. [0066]
enhanced efficiency of the RIP and RIS processes by means of
improved design and operating procedures involved in the screening
processes to remove any oversize material in the original feed pulp
and/or feed solution and/or any solid neutralising agent used for
pH control purposes. [0067] enhanced efficiency of the RIP and RIS
processes by means of pH control prior to and during the processes
to maximise the loading capacity and/or the selectivity and/or
elution of the resin. [0068] enhanced efficiency of the RIP and RIS
processes by means of pH control prior to and during the processes
to eliminate non-target metals through precipitation mechanisms.
[0069] enhanced efficiency of the RIP process by means of improved
methods of introduction of resin to viscous RIP circuits to ensure
adequate resin mixing within the pulp and avoid resin floating
and/or short circuiting. [0070] enhanced efficiency of the RIP and
RIS processes by means of an improved resin transfer system which
allows water to be used to fluidise the resin enabling its
efficient transfer while minimising resin losses through attrition
while at the same time ensuring that resin transfer can be
accomplished with minimal effect on circuit water balance. [0071]
enhanced efficiency of the RIP and RIS processes when used to treat
complex feed pulps and solutions containing two or more soluble
target metals by means of using a single resin in the circuit but
changing the pH across different stages of the circuit to optimise
the uptake/removal and recovery of different target metals. [0072]
enhanced efficiency of the RIP and RIS processes when used to treat
complex feed pulps and solutions containing two or more soluble
target metals by means of using more than one type of resin to
separate and remove each of the soluble target metals independently
of the other soluble target metals. In one preferred embodiment the
two or more types of resin may be contained within separate
columns. In another preferred embodiment the two or more types of
resin may be mixed together and contained within the same column or
columns [0073] enhanced efficiency of the RIP and RIS processes by
means of appropriate temperature control of the incoming feed pulps
or solutions and/or of the resin columns in their loading and/or
washing and/or eluting duties.
[0074] In the preceding description of the invention and in the
claims which follow, except where the context requires otherwise
due to express language or necessary implication, the words
"comprise" or variations such as "comprises" or "comprising" are
used in an inclusive sense, i.e., specify the presence of stated
features, but not preclude the presence or addition of further
features in various embodiments of the invention.
[0075] It is to be understood that in this invention the preferred
embodiments are not limited to those particular materials
described, as these may vary. It is also to be understood that the
terminology used herein is for the purpose of describing particular
embodiments only, and is not intended to limit the scope of the
present invention in any way.
[0076] It is to be noted that, as used herein, the singular forms
of "a", "an" and "the" include the plural unless the context
clearly requires otherwise. Unless defined otherwise, all technical
and scientific terms herein have the same meanings as commonly
understood by one of ordinary skill in the art to which the
invention belongs.
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