WO2019161448A1

WO2019161448A1 - Method for the selective separation and recovery of nickel, copper and cobalt

Info

Publication number: WO2019161448A1
Application number: PCT/AU2019/050145
Authority: WO
Inventors: Bryn Harris; Carl White
Original assignee: Nmr 360 Inc; Urban Mining Pty Ltd
Priority date: 2018-02-22
Filing date: 2019-02-22
Publication date: 2019-08-29

Abstract

A method is disclosed for the recovery of nickel, copper and cobalt as pure salts from mixtures of these metals, and especially when the ratio of the individual metals to each other in the feed solution is less than five (5), and close to unity. Such feed solutions may originate from the leaching of recycled lithium ion batteries, or other similar materials such as alliages blancs. Normally, such separations are very difficult to carry put due to the similar nature of the chemistry of these three metals. The process comprises, after purification to remove iron and aluminium, a primary crystallisation, wherein an impure form of cobalt sulphate is generated. This is a preliminary separation. Thereafter, a series of selective ion exchange processes is employed for the separation and purification of the three metals, generating pure sulphate salts of nickel, copper and cobalt.

Description

METHOD FOR THE SELECTIVE SEPARATION AND RECOVERY OF

NICKEL, COPPER AND COBALT

FIELD OF THE INVENTION

0001 The present invention relates generally to methods for the selective separation and recovery of pure salts of nickel, copper and cobalt from feedstocks containing economically practicable amounts of each metal. More specifically, it discloses a method for the recovery from, and the production of high-purity salts of nickel, copper and cobalt suitable for the cathode material of lithium ion batteries.

BACKGROUND OF THE INVENTION

0002 The use of rechargeable Li-ion batteries has been growing steadily, and this growth will increase considerably as electric cars become more reliable and available, coupled with the increasing demand for off-peak mass electric power storage. It is variously estimated that there will be a significant shortfall of high-purity cobalt feedstocks, in particular, by the year 2020.

0003 With the exception of the Bou Azzer deposit in Morocco, which accounts for about 0.3% of world production, there are no primary cobalt mines operating, with the metal generally being recovered as the by-product of copper (predominantly the Central African Copperbelt) or nickel (Canada, Western Australia, Russia and laterites) mining. With the former, the cobalt to nickel ratio is generally of the order of 100: 1 in the cobalt sulphate solution derived from the leaching of concentrates, whereas in the latter, it is typically 1 : 10. Thus, in conventional processing, the requirement is either to remove a small amount of nickel from cobalt solutions, or a small amount of cobalt from nickel solutions.

0004 It can also be expected that the recovery of especially cobalt, but also nickel and copper from the recycling of spent Li-ion and similar batteries, and specialty alloys, will become increasingly significant. However, unlike the mining of primary sources referred to above, the ratio of cobalt to nickel (and to manganese) can often be close to unity, as well as there being appreciable copper values. Thus, rather than just a purification problem, each of the metals represents a major recovery opportunity, but at the same time, also a separation problem. There are presently no operations that are separating all of these metals in a state of high-purity as valuable commodities from such feedstocks.

0005 Current commercial practice, as practiced on the African Copperbelt at the plants of Chambishi, Nkana and Luilu, for example, where there is significant copper, but relatively little nickel, is to first recover an impure copper product by electrowinning. This still leaves some copper in solution (0.5- 1.0 g/L), which is subsequently removed by neutralisation with lime, and, hence is lost.

0006 Small amounts of nickel are removed, but not recovered in a useful product, via precipitation with or with lime, or more recently via ion exchange. C. Bailey, G.B. Harris, R. Kuyvenhoven and J. du Plessis, in a paper entitled Removal of Nickel from Cobalt Sulphate Electrolyte using ISEP® Continuous Ion Exchange, published in Proceedings of Copper, Cobalt, Nickel and Zinc Recovery, International Conference, Victoria Falls, Zimbabwe, 16-18 July, 2001, SAIMM, Johannesburg described such a process in commercial operation at the Chambishi Cobalt Plant in Zambia.

0007 Douglas S. Flett, in an article entitled Cobalt-Nickel Separation in Hydrometallurgy: a Review, and published in Chemistry for Sustainable Development 12(2004), pages 81-91, reviewed all of the processes that have been used to effect separation of small amounts of cobalt from nickel and vice versa. He concluded that solvent extraction processes were superseding precipitation processes for removing cobalt from nickel, and that ion exchange, such as described in the preceding article, was the only method to effectively remove nickel from cobalt in a sulphate medium.

0008 Oxidative precipitation processes for cobalt removal from nickel solutions, which have relevance to the current invention, were also reviewed. Much like is the case for the equivalent solvent extraction and ion exchange processes, it was noted that the issue with all of them was pH control, especially if significant amounts of cobalt were present, i.e. close to the 1 : 10 ratio referred to above. It was further noted that even strong oxidants such as Caro’s Acid (H2SO5, peroxy monosulphuric acid), sometimes referred to as a superoxidant, were generally inadequate for effective and efficient cobalt removal. Additionally, all such reagents generate acid, requiring substantial amounts of base to be added at the same time. 0009 G.M. Dunn, H.W. Schubert and H.E. Holliday, in an article entitled Nickel Cobalt Separation with Superoxidants, published in Hydrometallurgy and Refining of Nickel and Cobalt, Volume 1 of Nickel Cobalt 97, Edited by W.C. Cooper and I. Mihaylov, CIM, Montreal, 1997, pages 197-210, describe the use of Caro’s Acid and ozone as methods of oxidative precipitation. As with the article by Flett, it was noted that pH control is important, and also that the cobalt products contained significant amounts of nickel, requiring their re -processing. The large amounts of nickel co-precipitated were undoubtedly due to the long residence times employed.

0010 With recycling, especially from the various types of lithium-ion batteries, more particularly from the so-called NMC (nickel-manganese-cobalt) batteries, and alloys such as alliages blancs, the ratios of cobalt to nickel are very much lower than those referred to above, often close to unity. The oxidative precipitative processes referred to above are inadequate, since they require large amounts of base, and generally co-precipitate large amounts of nickel along with the cobalt.

0011 Eric Gratz, Qina Sa, Diran Apelian and Yan Wang, in an article entitled A Closed Loop Process for Recycling Spent Lithium Ion Batteries, published in Journal of Power Sources 262 (2014), pages 255-262, describe a process for recycling spent batteries. Their mode of recovery is to precipitate a combined nickel-cobalt-manganese hydroxide, the composition of which is then adjusted to re-create the original battery material. This mode of recycling is also reported in a number of other articles.

0012 Pratima Meshram, B.D. Pandey and T.R. Mankand, in an article entitled Hydrometallurgical Processing of Spent Lithium Ion Batteries (LIBs) in the Presence of a Reducing Agent with Emphasis on Kinetics of Leaching, published in Chemical Engineering Journal 281 (2015), pages 418-427, describe a method of recovering cobalt from the leach solutions by precipitation of cobalt oxalate with oxalic acid. However, the considerable co precipitation of nickel oxalate occurred, giving a cobalt purity of -95%. A number of other researchers have reported similar processes using oxalic acid.

0013 It is apparent from the foregoing that there is not yet any universal process, or combination of processes, for the high recovery of a pure form of cobalt from concentrated leach solutions where the Co/Ni ratio is <5. It would be beneficial if there were such a process, enabling high recoveries of cobalt, and the metals usually associated with cobalt, namely manganese and nickel, from a variety of different feedstocks. Such is important, since there is projected to be a significant shortfall in cobalt availability in the next half-decade.

0014 It is also apparent that there is no universal process wherein all of the copper, cobalt and nickel are first selectively separated and then recovered in a pure form when there are substantial amounts of all the metals present. Of particular importance is the purity of the recovered material, because electrochemical processes, such as those fundamental to battery operation, demand high levels of purity if they are to be efficient.

0015 An object of the invention is to address at least one of the problems of prior art processes, and/or to provide modified or alternative processes.

SUMMARY OF THE INVENTION

0016 In accordance with a broad aspect of the present invention, a process is described for the recovery of nickel, copper and cobalt from various feed materials, including, but not limited to, base metal mining ores, concentrates and tailings, scrap alloys such as alliages blancs, and from spent lithium-based batteries. Specifically, methods for the recovery of nickel, copper and cobalt in a pure form are described when all of the components are present in a high concentration.

0017 In a first aspect of the invention, there is provided a process including: contacting a liquor containing Co, Cu, Ni, and one or more metal impurities with ammonia while maintaining a pH of the liquor in the range of pH 2 to pH 4 to precipitate one or more metal impurities from the liquor; and separating the precipitate including the one or more metal impurities from the liquor.

0018 In an embodiment, prior to the step of contacting the liquor with ammonia, the method includes: subjecting the liquor to a crystallisation process to crystallise a portion of the Co in the liquor; and separating the crystallised portion of the Co from the liquor to form Co-containing crystals. 0019 In one form of this embodiment, prior to subjecting the liquor to the crystallisation process, the liquor has a Co/Ni ratio of <5.

0020 In an embodiment, the step of contacting the liquor with ammonia is conducted at a temperature of from ambient up to 100 °C. Preferably, the temperature is from 50 °C. More preferably, the temperature is from 60 °C. Even more preferably, the temperature is from about 70 °C. Most preferably, the temperature is from about 80 °C. Alternatively, or additionally, it is preferred that the temperature is up to 95 °C. More preferably, the temperature is up to 90 °C.

0021 The skilled addressee will appreciate that the type of Co-containing crystals that are formed will depend on the nature of the liquor. It is preferred that the liquor is sulphate, chloride, or nitrate liquor, in which case the Co-containing crystals are hydrates of: C0SO4, C0CI2, or C0NO3 with various degrees of hydration respectively.

0022 In one form of this embodiment, from 10-40% of the cobalt in the liquor is crystallised.

0023 In one form of this embodiment, the cobalt crystals contain <2% Ni and <2% Cu + Mn.

0024 In an embodiment, after the step of separating the precipitate, the process further includes contacting the liquor with a Cu ion exchange resin to form a Cu-loaded resin and a Cu-lean liquor. It is preferred that the Cu ion exchange resin includes an iminodiacetate functionality. It is preferred that the step of contacting the liquor with a Cu ion exchange resin includes maintaining the pH of the liquor at a pH of pH 4 or less. Preferably the pH is from pH 1 up to pH 4. More preferably, the pH is from pH 1 up to pH 3. Most preferably, the pH is about pH 2.

0025 In one form of the above embodiment, the process further includes contacting the Cu- loaded resin with an eluant to form a Cu-rich eluate substantially free of Ni and Co. Preferably, the eluant is a sulfuric acid solution, having a sulfuric acid concentration of from 2% and up to 10%. More preferably, the sulfuric acid concentration is from 4%. Even more preferably, the sulfuric acid concentration is from 6%. Most preferably, the sulfuric acid concentration is from 8%. Alternatively, or additionally, it is preferred that the sulfuric acid concentration is sufficient to provide a Cu-rich eluate with a sulfuric acid concentration of 1M. 0026 In a further form, the process further includes contacting the Cu-lean liquor with a Ni ion exchange resin to form a Ni-loaded resin and a Cu-, Ni-lean liquor. It is preferred that the Ni ion exchange resin includes a bis-picolylamine functionality. It is preferred that the step of contacting the Cu-lean liquor with a Ni ion exchange resin includes maintaining the pH of the Cu-lean liquor at a pH of pH 4 or less. Preferably the pH is from pH 1 up to pH 4. More preferably, the pH is from pH 1 up to pH 3. Most preferably, the pH is about pH 2.

0027 In one form of the above embodiment, the process further includes contacting the Ni- loaded resin with an eluant to form a Ni-rich eluate substantially free of Cu and Co. Preferably, the eluant is a sulfuric acid solution, having a sulfuric acid concentration of from 2% and up to 10%. More preferably, the sulfuric acid concentration is from 4%. Even more preferably, the sulfuric acid concentration is from 6%. Most preferably, the sulfuric acid concentration is from 8%. Alternatively, or additionally, it is preferred that the sulfuric acid concentration is sufficient to provide a Ni-rich eluate with a sulfuric acid concentration of 1M.

0028 In one form of the above embodiment, the process additionally includes contacting the Cu- , Ni-lean liquor with a Co ion exchange resin to form a Co-loaded resin and a Cu-, Ni-, and Co lean liquor. It is preferred that the Co ion exchange resin includes a bis-picolylamine functionality or the Co ion exchange resin is a weak-base anion exchange resin including a complex amine functionality. It is preferred that the step of contacting the Cu-, Ni-lean liquor with the Co ion exchange resin includes maintaining the pH of the Cu, Ni-lean liquor at a pH of from about pH 2 up to about pH 6. More preferably, at a pH of from about 3. Even more preferably, at a pH of up to about 5. Most preferably, at a pH of about pH 4.

0029 In another form, the process further includes contacting the Co-loaded resin with an eluant to form a Co-rich eluate substantially free of Cu and Ni. Preferably, the eluant is a sulfuric acid solution, having a sulfuric acid concentration of from 2% and up to 10%. More preferably, the sulfuric acid concentration is from 4%. Even more preferably, the sulfuric acid concentration is from 6%. Most preferably, the sulfuric acid concentration is from 8%. Alternatively, or additionally, it is preferred that the sulfuric acid concentration is sufficient to provide a Co-rich eluate with a sulfuric acid concentration of 1M. 0030 In one or more forms,“substantially free of’ refers to an amount of less than 0.1 wt% of those components, preferably less than 0.0lwt%, most preferably less than 0.00 lwt%. In one or more forms the term“substantially free of’ defines that the concentration of those components is below a detectable threshold.

0031 In an embodiment, the one or more metal impurities is selected from the group consisting of: iron, aluminium, or combinations thereof.

0032 In an embodiment, the liquor is a sulphate, nitrate, or chloride liquor.

0033 In a second aspect of the invention, there is provided a process for recovering Cu, Ni, and Co from a liquor containing Co, Cu, Ni, and one or more metal impurities, the process including: subjecting the liquor to a crystallisation process to crystallise a portion of the Co in the liquor; separating the crystallised portion of the Co from the liquor to form a mother liquor; contacting the mother liquor with a precipitant to selectively precipitate one or more metal impurities from the liquor; separating the precipitate including the one or more metal impurities from the mother liquor; contacting the mother liquor with a Cu ion exchange resin to form a Cu-loaded resin and a Cu-lean liquor; stripping Cu from the Cu ion exchange resin with an eluant to form a Cu-rich eluate substantially free of Ni and Co; contacting the Cu-lean liquor with a Ni ion exchange resin to form a Ni-loaded resin and a Cu-, Ni-lean liquor; stripping Ni from the Ni ion exchange resin with an eluant to form a Ni-rich eluate substantially free of Cu and Co; contacting the Cu-, Ni-lean liquor with a Co ion exchange resin to form a Co-loaded resin and a Cu-, Ni-, and Co-lean liquor; and stripping Co from the Co ion exchange resin with an eluant to form a Co-rich eluate substantially free of Cu and Ni.

0034 In an embodiment, prior to the crystallisation process, the liquor has a Co/Ni ratio of <8. Preferably, the liquor has a Co/Ni ratio of <7. More preferably, the liquor has a Co/Ni ratio of <6. Most preferably, the liquor has a Co/Ni ratio of <5.

0035 In an embodiment of the second aspect, the precipitant is ammonia gas.

0036 In an embodiment of the second aspect, the step of contacting the liquor with a precipitant is conducted at a temperature of from ambient up to 100 °C. Preferably, the temperature is from 50 °C. More preferably, the temperature is from 60 °C. Even more preferably, the temperature is from about 70 °C. Most preferably, the temperature is from about 80 °C. Alternatively, or additionally, it is preferred that the temperature is up to 95 °C. More preferably, the temperature is up to 90 °C.

0037 In an embodiment, the Cu ion exchange resin includes an iminodiacetate functionality. It is preferred that the step of contacting the liquor with a Cu ion exchange resin includes maintaining the pH of the liquor at a pH of pH 4 or less. Preferably the pH is from pH 1 up to pH 4. More preferably, the pH is from pH 1 up to pH 3. Most preferably, the pH is about pH 2.

0038 In an embodiment, the Ni ion exchange resin includes a bis-picolylamine functionality. It is preferred that the step of contacting the Cu-lean liquor with a Ni ion exchange resin includes maintaining the pH of the Cu-lean liquor at a pH of pH 4 or less. Preferably the pH is from pH 1 up to pH 4. More preferably, the pH is from pH 1 up to pH 3. Most preferably, the pH is about pH

2.

0039 In an embodiment, the Co ion exchange resin includes a bis-picolylamine functionality or the Co ion exchange resin is a weak-base anion exchange resin including a complex amine functionality. It is preferred that the step of contacting the Cu-, Ni-lean liquor with the Co ion exchange resin includes maintaining the pH of the Cu, Ni-lean liquor at a pH of from about pH 2 up to about pH 6. More preferably, at a pH of from about 3. Even more preferably, at a pH of up to about 5. Most preferably, at a pH of about pH 4.

0040 In an embodiment, the eluant is a sulfuric acid solution, having a sulfuric acid concentration of from 2% and up to 10%. More preferably, the sulfuric acid concentration is from 4%. Even more preferably, the sulfuric acid concentration is from 6%. Most preferably, the sulfuric acid concentration is from 8%. Alternatively, or additionally, it is preferred that the sulfuric acid concentration is sufficient to provide a Cu-rich eluate with a sulfuric acid concentration of 1M.

0041 In an embodiment of the first and second aspects of the invention, the crystallised portion of the Co additionally includes Cu and Ni, and the process further includes: dissolving the crystallised portion of the Co in a solvent to form a Cu-, Ni-, and Co containing solution; contacting the Cu-, Ni-, and Co- containing solution with a Cu ion exchange resin to form a Cu-loaded resin and a Ni-, and Co-containing solution; stripping Cu from the Cu ion exchange resin with an eluant to form a Cu-rich solution substantially free of Ni and Co; contacting the Ni-, and Co-containing solution with a Ni ion exchange resin to form a Ni- loaded resin and a Co-containing solution substantially free of Cu and Ni; and stripping Ni from the Ni ion exchange resin with an eluant to form a Ni-rich solution substantially free of Cu and Co.

0042 In a form of the above embodiment, the step of dissolving the crystallised portion of the Co in a solvent includes dissolving the crystallised portion of the Co in water to form a Co containing aqueous solution having a Co concentration of from 0.5M to 2M. Preferably, the Co concentration is about 1M.

0043 In an embodiment, 10-40% of the cobalt in the liquor is crystallised.

0044 In an embodiment, the cobalt crystals contain <2% Ni and <2% Cu + Mn. 0045 In an embodiment, the process further includes: combining the Cu-rich eluant with the Cu-, Ni-, and Co- containing solution prior to the step of contacting the Cu-, Ni-, and Co- containing solution with the Cu ion exchange resin; and/or combining the Ni-rich eluant with the Ni-, and Co-containing solution prior to the step of contacting the Ni-, and Co-containing solution with the Ni ion exchange resin.

0046 In an embodiment, the one or more metal impurities is selected from the group consisting of: iron, aluminium, or combinations thereof.

0047 In an embodiment, the liquor is a sulphate, nitrate, or chloride liquor.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

0048 The embodiments of the present invention shall be more clearly understood with reference to the following detailed descriptions taken in conjunction with the accompanying drawing, Figure 1.

0049 The description, and the embodiments described therein, are provided by way of illustration of examples of particular embodiments of principles and aspects of the present invention. These examples are provided for the purposes of explanation and not of limitation, of those principles of the invention. In the description that follows, like parts and/or steps are marked throughout the specification and the drawing with the same respective reference numerals.

0050 Referring to Figure 1, there is shown a schematic representation of a method for the recovery of nickel, copper and cobalt and from a sulphate-based feed solution 10, which may have been derived from the leaching in a sulphuric acid medium of, for instance, but not limited to, recycled lithium ion batteries, alliages blancs, or base metal concentrates. The process has been conceived primarily for sulphate -bearing liquors, but it will be understood that the principles and techniques herein described apply equally to chloride and nitrate liquors.

0051 The first step in the process is crystallisation 11, wherein a substantial portion, up to 40% of the contained cobalt, is crystallised and recovered predominantly as an impure heptahydrate, COS0_4*7H₂0, although there may also be some hexahydrate, CoSO FFO, present. This step performs a primary separation of cobalt. Depending on the concentration of the feed liquor, the crystals may contain up to 2% of Ni, and 1% of Cu and Mn.

0052 The crystal slurry undergoes solid-liquid separation 12, which may be effected by any convenient means, such as, but not limited to, flocculation and thickening, filter press or vacuum belt filter. The solids 13 are the impure cobalt sulphate crystals referenced above.

0053 The filtrate 14 then undergoes a purification step 16, wherein ammonia gas is sparged into the solution in order to effect the precipitation of any iron and aluminium. It has been found that ammonia gas is the preferred reagent for this reaction, being far more effective than either caustic soda or caustic potash. Lime cannot be used as it results in the formation of a calcium-saturated solution, which causes both subsequent purity and scaling problems.

0054 Ammonia is not normally used in this way, but it has been found that the reaction is easier to control and that the solids so-formed filter much better than with more conventional neutralising agents. The reaction may be conducted at any temperature, but is most conveniently carried out at 60-l00°C, more preferably at 80-90°C. The pH of the reaction is controlled at 2.5-3.5, more preferably at 3.0-3.2, and most preferably at 3.2. It has been found that this value of pH gives good-filtering solids, removes essentially all of the iron and aluminium, with virtually no loss of cobalt, copper or nickel. At lower pH values (<l.8), both lithium and ammonium jarosites will form, but these leave a substantial heel of iron remaining in solution. By raising the pH to the above values, all of the iron (and aluminium) is essentially removed.

0055 The purification slurry 17 undergoes solid-liquid separation 18, which may be effected by any convenient means, such as, but not limited to, flocculation and thickening, filter press or vacuum belt filter. The solids 19, being a mixture of iron and aluminium hydroxides, are sent for disposal.

0056 The filtrate 20 is essentially a solution of copper, nickel and cobalt sulphates. Other ions, such as lithium or manganese may also be present. Optionally (not shown in Figure 1), the latter may be removed by oxidative precipitation, but its presence has no impact on the following recovery and purification steps. Likewise for lithium. 0057 The filtrate 20 next undergoes copper ion exchange 21, wherein copper is selectively recovered. It has been found that a resin with iminodiacetate functionality is very effective for selectively recovering copper. It has also been found that feed solution pH is very important. At pH 2.0, copper is selectively loaded, whereas if the pH of the feed is at 4.0, especially when there are high concentrations of cobalt present, the copper loads first, but the cobalt will then crowd the copper off the resin. Thus, a feed pH of 2.0 is preferred, and with the resin in its hydrogen form.

0058 The copper-loaded resin, after backwashing, is stripped with sulphuric acid 22. Ideally, acid of 5-10% strength is used, wherein strip solutions 23 of 60-65 g/L Cu (1M) can be achieved.

0059 The copper-barren solution 24 then undergoes nickel ion exchange 25, wherein nickel is selectively recovered. It has been found that a resin with bis-picolylamine functionality is very effective for selectively recovering nickel. More especially, it has further been shown that separation and recovery is more effective when resin with a uniform particle size (UPS) is used. The pH of the copper-barren solution (2.0) is ideal for effecting this separation.

0060 A small amount of cobalt also loads onto this resin, which is easily removed by a dilute acid wash (not shown). The concentration of the acid wash is 1-5% H2SO4, ideally 3-4%, and the wash solution is returned to the feed solution.

0061 The nickel-loaded resin, after backwashing, is stripped with sulphuric acid 26. Ideally, acid of 10% strength is used, wherein strip solutions 27 of 60-65 g/L Ni (1M) can be achieved.

0062 The nickel-barren solution 28 then proceeds to cobalt mop-up recovery 29, which is conveniently effected by a weak base complex amine resin. In this case, a higher pH is required, ideally 4.0-5.0, and preferably 4.5. The cobalt barren solution 32 is either recycled to the leaching stage of the circuit 33, or if valuable metals such as lithium are present, to a metal recovery circuit 34.

0063 The cobalt-loaded resin is stripped with 5-10% sulphuric acid 30, preferably 8-10% to generate a cobalt strip solution 31 containing 60-65 g/L Co (1M).

0064 Impure cobalt sulphate 13 from the crystallisation step is re-dissolved 35 in water to give a solution of approximately 1M. This solution 36 contains minor amounts of impurities, such as copper and nickel, which co-crystallised with the cobalt. This then undergoes a second stage of copper ion exchange 37 with the same iminodiacetate resin as described in paragraph 57. Optionally, the strip solution from the first copper ion exchange 23 may also be passed through this resin as a final purification stage, or it may be combined directly with the strip solution 39.

0065 The copper-loaded resin is again stripped with sulphuric acid 38 as described previously, the resulting strip solution being pure copper sulphate, which may be used as-is, or crystallised to its pentahydrate, CuS0_4*5H₂0.

0066 As in the main circuit, the copper-barren solution 40 then undergoes a second stage of nickel ion exchange 41, wherein nickel is again selectively recovered using the same bis- picolylamine resin as previously. As for the copper resin, optionally, the strip solution from the first nickel ion exchange 27 may also be passed through this resin as a final purification stage, or it may be combined directly with the strip solution 43.

0067 The nickel-loaded resin is again stripped with sulphuric acid 42 as described previously, the resulting strip solution 43 being pure nickel sulphate, which may be used as-is, or crystallised to its hexahydrate, NiSCU^ehbO.

0068 The nickel-barren solution 44 is pure cobalt sulphate, which may be combined with the cobalt strip solution 31 from the ion exchange circuit 29, to a pure, concentrated cobalt sulphate solution, which may be used as-is or crystallised to its heptahydrate, CoSO TbO.

0069 The principles of the present invention are illustrated by the following examples, which are provided by way of illustration, but should not be taken as limiting the scope of the invention.

Example 1

0070 A solution analysing 4 g/L Cu, 345 mg/L Co and 222 mg/L at pH 2.0 was passed downflow at 2 BV/hour through a 25mL of an iminodiacetate resin. The composite barren solution analysed 304 mg/L Co and 198 mg/L Ni, with copper being undetectable. After backwashing with water, the resin was stripped with 5% sulphuric acid. The first BV of stripped solution analysed 30.8 g/L Cu, 29 mg/L Co and 97 mg/L Ni, and the second BV of stripped solution analysed 39.9 g/L Cu, 3 mg/L and 15 mg/L Ni.

0071 This example shows that copper can be recovered from solutions containing both cobalt and nickel, and concentrated significantly, with almost no cobalt or nickel present (second stripping BV).

Example 2

0072 A solution analysing 40 g/L Co, 2.5 g/L Cu and 1.5 g/L Ni at pH 2.0 was passed downflow through a 25-mL bed of an iminodiacetate resin at a flowrate of 5 BV/hour. After the passage of 16 BV, there was no detectable copper in the solution exiting the column. The resin was not stripped, as it had not been fully loaded.

Example 3

0073 A copper-free solution, analysing 25.9 g/L Co and 2.10 g/L (Co/Ni ratio of 12.3) was passed downflow through a 25-mL bed of a bis-picolylamine resin at 3 BV/hour. Loading was continued until the nickel concentration of the exit solution equalled that of the feed solution. The ratio of C/Ni on the loaded resin was found to 0.26, demonstrating that nickel can be selectively recovered from solutions containing high concentrations of cobalt.

Example 4

0074 The loaded resin from Example 3 was stripped with both 25 g/L and 100 g/L sulphuric acid. It was found that the dilute acid removed 80% of the loaded cobalt and <10% of the loaded nickel, whereas the strong acid completely stripped the resin of both metals. Subsequently, stripping a fully-loaded resin with first dilute acid removed the cobalt and secondly recovered the nickel. The analysis of the Ni-strip solution was 16 g/L Ni and 0.2 g/L Co.

Claims

CLAIMS What is claimed is:

1. A process including: contacting a liquor containing Co, Cu, Ni, and one or more metal impurities with ammonia while maintaining a pH of the liquor in the range of pH 2 to pH 4 to precipitate one or more metal impurities from the liquor; and separating the precipitate including the one or more metal impurities from the liquor.

2. The process of claim 1 , wherein, prior to the step of contacting the liquor with ammonia, the method includes: subjecting the liquor to a crystallisation process to crystallise a portion of the Co in the liquor; and separating the crystallised portion of the Co from the liquor.

3. The process of claim 1 or 2, wherein, after the step of separating the precipitate, the process further includes contacting the liquor with a Cu ion exchange resin to form a Cu-loaded resin and a Cu-lean liquor.

4. The process of claim 3, wherein the process further includes contacting the Cu-loaded resin with an eluant to form a Cu-rich eluate substantially free of Ni and Co.

5. The process of claim 3 or 4, wherein the process further includes contacting the Cu-lean liquor with a Ni ion exchange resin to form a Ni-loaded resin and a Cu-, Ni-lean liquor.

6. The process of claim 5, wherein the process further includes contacting the Ni-loaded resin with an eluant to form a Ni-rich eluate substantially free of Cu and Co.

7. The process of claim 5 or 6, wherein the process further includes contacting the Cu-, Ni- lean liquor with a Co ion exchange resin to form a Co-loaded resin and a Cu-, Ni-, and Co-lean liquor.

8. The process of claim 7, wherein the process further includes contacting the Co-loaded resin with an eluant to form a Co-rich eluate substantially free of Cu and Ni.

9. A process for recovering Cu, Ni, and Co from a liquor containing Co, Cu, Ni, and one or more metal impurities, the process including: subjecting the liquor to a crystallisation process to crystallise a portion of the Co in the liquor; separating the crystallised portion of the Co from the liquor to form a mother liquor; contacting the mother liquor with a precipitant to selectively precipitate one or more metal impurities from the liquor; separating the precipitate including the one or more metal impurities from the mother liquor; contacting the mother liquor with a Cu ion exchange resin to form a Cu-loaded resin and a Cu-lean liquor; stripping Cu from the Cu ion exchange resin with an eluant to form a Cu-rich eluate substantially free of Ni and Co; contacting the Cu-lean liquor with a Ni ion exchange resin to form a Ni-loaded resin and a Cu-, Ni-lean liquor; stripping Ni from the Ni ion exchange resin with an eluant to form a Ni-rich eluate substantially free of Cu and Co; contacting the Cu-, Ni-lean liquor with a Co ion exchange resin to form a Co-loaded resin and a Cu-, Ni-, and Co-lean liquor; and stripping Co from the Co ion exchange resin with an eluant to form a Co-rich eluate substantially free of Cu and Ni.

10. The process of claim 9, wherein the precipitant is ammonia gas.

11. The process of any one of claims 3 to 10, wherein the Cu ion exchange resin includes an iminodiacetate functionality, and the step of contacting the liquor with a Cu ion exchange resin includes maintaining the pH of the liquor at a pH of less than pH 4.

12. The process of any one of claims 5 to 10, wherein the Ni ion exchange resin includes a bis- picolylamine functionality, and the step of contacting the liquor with a Ni ion exchange resin includes maintaining the pH of the Cu-lean liquor at a pH of less than pH 4.

13. The process of any one of claims 7 to 10, wherein the Co ion exchange resin includes a bis-picolylamine functionality or the Co ion exchange resin is a weak-base anion exchange resin including a complex amine functionality, and the step of contacting the Cu-, Ni-lean liquor with the Co ion exchange resin includes maintaining the pH of the Cu, Ni-lean liquor at a pH of from about pH 2 to about pH 6.

14. The process of claim 2 or 9, wherein the crystallised portion of the Co additionally includes Cu and Ni, and the process further includes: dissolving the crystallised portion of the Co in a solvent to form a Cu-, Ni-, and Co containing solution; contacting the Cu-, Ni-, and Co- containing solution with a Cu ion exchange resin to form a Cu-loaded resin and a Ni-, and Co-containing solution; stripping Cu from the Cu ion exchange resin with an eluant to form a Cu-rich solution substantially free of Ni and Co; contacting the Ni-, and Co-containing solution with a Ni ion exchange resin to form a Ni- loaded resin and a Co-containing solution substantially free of Cu and Ni; and stripping Ni from the Ni ion exchange resin with an eluant to form a Ni-rich solution substantially free of Cu and Co.

15. The process of any one of claims 2, 9, or 14, wherein from 10-40% of the cobalt in the liquor is crystallised.

16. The process of any one of claims 2, 9, 14, or 15, wherein the cobalt crystals contain <2% Ni and <2% Cu + Mn.

17. The process of claim 14, wherein the process further includes: combining the Cu-rich eluate with the Cu-, Ni-, and Co- containing solution prior to the step of contacting the Cu-, Ni-, and Co- containing solution with the Cu ion exchange resin; and/or combining the Ni-rich eluate with the Cu-lean, Ni-, and Co-containing solution prior to the step of contacting the Ni-, and Co-containing solution with the Ni ion exchange resin.

18. The process of any one of claims 4, 6, 8, 9, or 14 wherein the or each eluant is a sulfuric acid solution, having a sulfuric acid concentration of from 2% and up to 10%.

19. The process of any one of the preceding claims, wherein the one or more metal impurities is selected from the group consisting of: iron, aluminium, or combinations thereof.

20. The process of any one of the preceding claims, wherein the liquor is a sulphate, nitrate, or chloride liquor.