Selective precipitation of cobalt and nickel salts from NMC feedstocks

Abstract

The disclosure relates to a method for selectively precipitating Ni and / or Co from amongst an aqueous stream of Ni, Co and Mn sulphate in solution. The method comprises a series of pH adjustment steps optionally comprising dilution, wherein the pH adjustment and / or dilution is carried out using the liquid product of a downstream precipitation step.

Description

[0001] SELECTIVE PRECIPITATION OF COBALT AND NICKEL SALTS FROM NMC FEEDSTOCKS

[0002] TECHNICAL FIELD

[0003] The disclosure relates to a method comprising selective precipitation of Ni and / or Co from amongst Ni, Co and Mn in a feedstock. The method comprises a series of pH adjustment and dilution steps, to precipitate an Ni, Co and / or Mn oxy precipitate. At least part of a dilution step is carried out using a liquid product formed in a downstream precipitation step.

[0004] BACKGROUND

[0005] With the increasing demand for Lithium-Ion Batteries (LIBs), there is a corresponding rise in the need for the chemicals used in their production, particularly battery-grade metals such as Nickel (Ni) and Cobalt (Co). In the LIBs manufacturing and recycling processes, these metals are primarily used in the form of sulphate salts, such as in the production of Precursor Cathode Active Material (pCAM).

[0006] When obtained from primary sources, nickel and cobalt are typically firstly recovered from the ores and concentrates in form of pure metals through a series of pyro- electrometallurgical refining operations. These metals are then used to produce nickel and cobalt sulphate salts by dissolving in sulfuric acid. A similar concept is followed when producing nickel and cobalt sulphate salts from the secondary sources; black mass (mixture of the anode and cathode active material obtained after mechanical processing), is leached by sulfuric acid converting the nickel and cobalt from their respective oxides into the sulphate solution.

[0007] However, during the leaching process, other metals are transferred into the pregnant leaching solution (PLS) as well. Typical impurities introduced into the system include manganese (Mn), magnesium (Mg) and iron (Fe), and other minor metals such as aluminium (Al), calcium (Ca), zinc (Zn), and copper (Cu). To ensure the purity of the final nickel and cobalt sulphate salts, the leaching process is followed by a series of purification steps before they are crystallized into battery-grade sulphates. The purification step typically comprises specific pH levels to selectively remove impurities and precipitate Ni and Co metal salts.

[0008] However, known methods of precipitating nickel and cobalt sulphates from purified PLS, typically leaves a significant amount of nickel and cobalt in solution. As a result, downstream operations are again required to recover these metals by reaction with a basifying agent.

[0009] Commonly used basifying agents for effective pH control include sodium or calcium hydroxide, or magnesium oxide. However, these basifying agents have drawbacks. Calcium hydroxide can lead to the formation of insoluble calcium sulphate precipitates, contaminating the nickel and cobalt. Sodium hydroxide results in the production of sodium sulphate, which is of low value and poses environmental risks. Magnesium oxide, while effective, is costly and may contaminate the final precipitate with undissolved magnesium.

[0010] Accordingly, there is a need for an alternative basifying agents and methods of recovering nickel and cobalt from a PLS.

[0011] SUMMARY

[0012] The object of the present disclosure is to a method that is resource-efficient, environmentally-friendly, provides a high selective recovery rate, a low wt% of impurities in the recovered metals and has a low OPEX.

[0013] In a first aspect, the disclosure provides a method of selectively recovering Ni and / or Co from a feedstock comprising Ni, Co and Mn sulphate in solution comprising; providing a feedstock comprising Ni, Co, and Mn sulphate in solution as an aqueous stream; performing a first precipitation step by diluting the stream and increasing the pH of the stream by at least 0.1 pH units to a first pH of from 7.5 to 9.0 to form an Ni and / or Co oxy-rich precipitate and a liquor; optionally removing the Ni and / or Co oxy-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the pH by at least 0.1 pH units to a second pH of above 8.5 to form an Mn oxy-rich precipitate and a liquor; wherein at least part of a dilution is carried out using a liquid product of a precipitation step carried out at a pH higher than the pH of the feedstock.

[0014] While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example and will be described in detail. It should be understood, however, that other embodiments, beyond the particular embodiments described, are possible as well. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are covered as well.

[0015] The above discussion is not intended to represent every example embodiment or every implementation within the scope of the current or future Claim sets. The figures and Detailed Description that follow also exemplify various example embodiments. Various example embodiments may be more completely understood in consideration of the following Detailed Description.

[0016] BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 shows a flow diagram of steps of the method of the disclosure, with examples of the pH ranges used in each step.

[0018] Figure 2 shows an example of a recycling loop wherein the liquid products of the second precipitation step are used in dilution of a pre and / or first precipitation step, with examples of the pH ranges used in each step.

[0019] Figure 3 shows an example of a recycling loop wherein a liquid product of a bulk precipitation step is used in dilution of a pre-, first and / or second precipitation step, with examples of the pH ranges used in each step.

[0020] Figure 4 shows an example of a recycling loop wherein the liquid product of a first precipitation step is used in dilution adjustment of the first precipitation, with examples of the pH ranges used in each step.

[0021] Figure 5 shows the flow diagram of the method used in Example 1.

[0022] Figure 6 shows the difference in Ni, Co and Mn precipitation as a function of pH and dilution for the method depicted in Figure 5.

[0023] Figure 7 shows the flow diagram of the method used in Example 2.1

[0024] Figure 8 shows the difference in Ni, Co and Mn precipitation as a function of pH for the method depicted in Figure 7.

[0025] Figure 9 shows the flow diagram of the method used in Example 2.2. Figure 10 shows the difference in Ni, Co and Mn precipitation as a function of pH for the method depicted in Figure 9.

[0026] Figure 11 shows a flow diagram of the method used in Example 2.3.

[0027] Figure 12 shows the difference in Ni, Co and Mn precipitation as a function of pH for the method depicted in Figure 11.

[0028] DETAILED DESCRIPTION

[0029] The disclosure relates to a method of selectively precipitating Ni and / Co from amongst Ni, Co and Mn in a feedstock.

[0030] Selective precipitation

[0031] The method of the disclosure provides selective recovery of transition metals by precipitating the transition metals in the form of an "oxy" precipitate (i.e. a transition metal oxy precipitate). In the context of the disclosure a transition metal oxy precipitate encompasses oxides, hydroxides and oxyhydroxides.

[0032] In the context of the disclosure, selective precipitation does not mean that complete precipitation of the desired metal(s) is achieved, nor does it mean that no precipitation of undesired metal(s) is achieved.

[0033] Instead, selective recovery refers to a process in which selected metal(s) are precipitated to a higher degree than undesired metal(s) thereby altering the ratio of the transition metals in a feedstock or liquor.

[0034] Specifically, the method of the disclosure provides selective recovery of Ni and / Co from a feedstock comprising Ni, Co and Mn. Accordingly, the precipitates of the disclosure are Ni oxy precipitates, Co oxy precipitates and Mn oxy precipitates. That is, the Ni / Co / Mn oxy precipitates may be Ni hydroxide (Ni(OH)2), Ni oxyhydroxide (NiOOH) and Ni oxide; Co hydroxide (Co(OH)2), Co oxyhydroxide (CoOOH) and Co oxide; and Mn hydroxide (Mn(OH)2), Mn oxyhydroxide (MnOOH) and Mn oxide.

[0035] Typically, the metals will precipitate in the hydroxide form, however they may oxidize to the oxyhydroxide or oxide form during the course of a precipitation step, or in a subsequent precipitation step. Accordingly, longer processing times or processes comprising multiple cycles may result in a higher concentration of oxyhydroxide and oxide precipitates.

[0036] Typically, the precipitates are crystalline.

[0037] The method of the disclosure provides selective precipitation by a series of dilution and pH adjustment steps. In particular, the method of the disclosure provides selective precipitation by a series of pH increase steps. These steps are a first and second precipitation step, and an optional pre-precipitation and bulk precipitation step, wherein the bulk precipitation is performed on a diverted stream.

[0038] An embodiment of the disclosure relates to a method wherein the second pH is at least 0.1 pH unit higher than the first pH. For instance, the second pH is at least 0.2, 0.3, 0.4 or 0.5 pH units higher than the first step.

[0039] An embodiment of the disclosure relates to a method wherein the first pH is at least 0.1 pH unit higher than the pre-precipitation pH. For instance, the first pH is at least 0.2, 0.3, 0.4 or 0.5 pH units higher than the pre-precipitation step.

[0040] An embodiment of the disclosure relates to a method wherein the bulk pH is at least 0.1 pH units higher than the pH of the diverted stream. For instance, the bulk pH is at least 0.2, 0.3, 0.4 or 0.5 pH units higher than the pH of the diverted stream.

[0041] Feedstock

[0042] The method of the disclosure comprises selectively recovering Ni and / or Co from a feedstock. In the context of the disclosure, a feedstock is a composition comprising NiSCk, CoSO4 and MnSCk wherein the Ni, Co and Mn sulphates are in solution, typically directly obtained from a source containing a mixture of these metals for instance by leaching in sulphuric acid. By "directly obtained" in this context is meant that no precipitation steps for the precipitating Ni, Co and / or Mn have been performed following the solubilisation of the Ni, Co, and Mn sulphates. That is, no precipitation steps according to the disclosure have been performed.

[0043] Typically a feedstock according to the disclosure has a pH of 7.0 or below, for instance an acidic pH such as 6.0 or below or 5.0 or below. To form the feedstock, a composition comprising Ni, Co and Mn may be leached in sulphuric acid. The composition comprising Ni, Co and Mn may be a primary source (e.g. a lateritic ore) or secondary source (a cathode, black mass or mixed hydroxide precipitates).

[0044] The feedstock is treated as an aqueous stream wherein Ni, Co and Mn sulphates are in solution.

[0045] Preferably the composition comprising Ni, Co and Mn is a secondary source. In such embodiments, the composition and subsequent feedstock will typically comprise lithium. For example, the composition comprises a lithium intercalation material comprising Ni, Co and Mn, also known as an 'NMC' material.

[0046] Preferably, the stream comprising Ni, Co and Mn sulphate in solution is obtained from a process for recycling a cathode active material.

[0047] Accordingly, the feedstock may additionally comprise Li sulphate in solution.

[0048] The feedstock may also comprise other impurities such an alkali metal and / or alkaline earth metals, particularly when the Ni, Co and Mn is from a secondary source. These metal impurities will typically be in the form of sulphates in solution.

[0049] An embodiment of the disclosure relates to a method wherein the stream comprising Ni, Co and Mn sulphate in solution further comprises Li and / or alkali metal or alkaline earth metal sulphate in solution. This may be a stream of the feedstock, or it may be a stream of the liquor from the first, second, pre- or bulk precipitation steps.

[0050] Liquid product

[0051] The method of the disclosure provides selective recovery by carrying out a series of pH adjustment and dilution steps wherein at least part of one dilution is carried out using the liquid product of a precipitation step carried out at a pH higher than the pH of the feedstock.

[0052] The method of the disclosure comprises a first precipitation step and a second precipitation step in that order wherein; the second precipitation step is carried out at a pH higher than the first precipitation step, for instance at least 0.1 pH unit higher. An embodiment of the disclosure relates to a method comprising a pre-precipitation step, a first precipitation step and a second precipitation in that order step wherein; the first precipitation step is carried out at a pH higher than the pH of the preprecipitation step, for instance at least 0.1 pH unit higher; and the second precipitation step is carried out at a pH higher than the first precipitation step, for instance at least 0.1 pH unit higher.

[0053] An embodiment of the disclosure relates to a method comprising a bulk precipitation step wherein; the bulk precipitation step comprises diverting part of an aqueous stream comprising Ni, Co and Mn sulphate in solution; and increasing the pH of the stream by at least 0.1 pH unit.

[0054] In some embodiments, the pH adjustment and dilution are carried out simultaneously e.g. by adding a basic liquid. In other embodiments, the dilution and pH adjustment are carried out stepwise. The order of the dilution and pH adjustment is not important, what is important is that each precipitation step results in a diluted stream at the specified pH in order to precipitate the desired metal.

[0055] The liquid product may be the liquor formed in a precipitation step, or it may be a slurry comprising the liquor and precipitates. The liquid products according to the disclosure typically comprise metal sulphates in solution. The metal sulphate may be NiSCk, CoSO4, MnSC , IJ2SO4 and / or NaSCk, and combinations thereof.

[0056] In the method of the disclosure, a dilution is carried out using a liquid product.

[0057] Surprisingly, it has been found that diluting an aqueous stream comprising Ni, Co and Mn sulphate in solution as part of a precipitation step provides improved precipitation selectivity. In particular, the degree of Mn precipitation is greatly reduced with increasing dilution, whilst the degree of Ni and Co dilution is not as affected.

[0058] In an aqueous stream comprising Ni, Co and Mn sulphate in solution, the ion interactions between the transition metals prevent selective precipitation, and the metals are likely to precipitate together. Conversely, when the concentration of the ions is reduced, the interactions between the ions is reduced and selective precipitation becomes possible.

[0059] Figure 6 shows the effect on dilution on the amount of metal precipitated and the selectivity amongst Ni, Co and Mn. Figure 6 a) shows that when NaOH is used to adjust the pH, without any additional dilution, Ni and Co precipitation at pH 7.0 is at around 80%. In contrast, less than 10% Mn is precipitated at the pH. The increase in Mn precipitation gradually increases with increasing pH until a pH of 8.5 whilst the Ni and Co precipitation remains relatively constant above this value. At pH above 8.5, Mn precipitation is also above 80%.

[0060] Figure 6 b)-d) show how different degrees of mass dilution affect the precipitation profiles of Ni, Co and Mn. Figure 6 b) includes a mass dilution of around 33 wt%, c) around 50 wt% and d) around 67 wt%.

[0061] As can be seen, the Ni and Co precipitation as a function of pH is relatively similar to the undiluted sample with around 80% precipitation achieved at a pH of around 7.5. In contrast, the Mn precipitation for all of samples b)-d) remains below 20% until a pH of around 8.2.

[0062] Accordingly, diluting the stream in addition to adjusting the pH increases the selectivity of the method and allows for the recovery of the majority of Ni and Co from a sample comprising Ni, Co and Mn.

[0063] A dilution according to the disclosure is a mass dilution. That is, the diluent may comprise liquids and solids, for example precipitates.

[0064] Preferably, a dilution according to the disclosure comprises adding 20-80wt% of a liquid product to a stream comprising Ni, Co and / or Mn sulphate in solution. For instance, a dilution may comprise adding 30-70wt%, 20-50wt%, 40-60wt% or 60-70wt% liquid product to a stream comprising Ni, Co and / or Mn sulphate in solution.

[0065] The degree of dilution may be determined by the mass flow rate of the two streams combined. For example, if the stream comprising Ni, Co and / or Mn sulphate in solution has a mass flow rate of 5m3 / min before dilution, and a diluent stream with a lm3 / min mass flow rate is added, 20wt% of the diluent was added to the stream in the dilution process.

[0066] In processes wherein a slurry liquid product is used as the diluent, the equipment will need to be suitable for processing said slurry.

[0067] The degree of dilution may be selected according to the desired recovery rate and selectivity of the recovery. For instance, if recovery rate of Ni and / or Co is a priority, a smaller dilution may be beneficial. Conversely, when a high selectivity is a priority, a larger dilution may be beneficial.

[0068] In some instances, using a higher degree of dilution means that a low pH may be used to obtain the same selectivity of recovery. Accordingly, a higher degree of dilution may be beneficial when the Ni, Co and / or Mn source is highly contaminated, with contaminants that precipitate at lower pH ranges.

[0069] By using a liquid product to perform the dilution, the environmental impact of the process is improved as it reduces the need for virgin material. This is in addition to reducing OpEX by recycling material previously deemed waste.

[0070] In some embodiments, the liquid product is the liquor formed in a precipitation step carried out at a higher pH than the pH of the feedstock wherein any precipitates have been removed. Precipitates can be removed using any suitable method, for instance filtration.

[0071] For example, the liquid product is the liquor formed in the second precipitation step wherein the Mn oxy-rich precipitates have been removed by filtration.

[0072] The liquor of the second precipitation will typically comprise residual amounts of Ni, Co and Mn sulphate in solution as well as other metal sulphates, for example Li sulphate when the feedstock comprises lithium. The liquor of downstream precipitation steps will additionally comprise a sulphate of any alkali metal or alkaline earth metal used as a basifying agent e.g. Na sulphate when NaOH is used in an upstream pH adjustment.

[0073] In some embodiments, the liquid product is a slurry comprising the liquor and metal oxy precipitates formed in a precipitation step carried out at a higher pH that the pH of the feedstock.

[0074] In some embodiments, a dilution is carried out using a liquid product that is a slurry. Such a liquid products may comprise transition metal oxy precipitates and transition, alkali or alkaline earth metal sulphates. For example, the metal oxy precipitate may be a hydroxide such as Ni(OH)?, Co(OH)2, or Mn(OH)2, and combinations thereof.

[0075] Examples of liquid products that are slurries include a slurry comprising the liquor and Ni, Co and Mn oxy precipitates formed in the bulk precipitates step, and a slurry comprising the liquor and Mn oxy rich precipitate formed in the second precipitation step. The precipitate formed in the bulk precipitation comprises Ni, Co, and / or Mn oxy precipitates. That is, the bulk precipitate Ni, Co, and / or Mn oxy precipitates, the composition of which may changed depending on the input stream and the bulk pH.

[0076] The precipitate formed in the second precipitation will also comprise Ni, Co, and Mn oxy precipitates, however it will be Mn-rich compared to the feedstock and / or precipitates of upstream precipitation steps.

[0077] Accordingly, liquids products that are slurries will typically have a high pH. When used for dilution, these slurries also typically contribute to the pH adjustment. Accordingly, in some embodiments, at least part of a pH adjustment is carried out using a liquid product, wherein the liquid product is a slurry (for example, comprising Ni(OH)?, Co(OH)2, and Mn(OH)? precipitates).

[0078] Conventional processes for precipitating transition metals rely on alkali metal and alkaline earth metal hydroxides as basifying agents. By using a liquid product for at least part of a pH adjustment, the amount of alkali metal and alkaline earth metal in the process is reduced. Accordingly, the drawbacks associated with common alkali metal and alkaline earth metals are also reduced. When the liquid product is slurry, a more efficient process, a recovered product with fewer impurities and a reduced environmental impact is obtained.

[0079] In addition, using a slurry as the liquid product provides a more resource-efficient process.

[0080] For example, when the liquid product used dilution is a slurry comprising the liquor and Ni, Co, and Mn oxy precipitates formed in bulk precipitation, a portion of the conventional basifying agent e.g. NaOH may be replaced as the liquid product has a basifying effect. This again increases the process efficiency, reduces OPEX and reduces the environmental impact.

[0081] Alkali metal and alkaline earth metal

[0082] In some embodiments, the pH adjustment comprises adding an alkali metal or an alkaline earth metal hydroxide or oxide. This addition may be instead of, or in addition to, a liquid product.

[0083] Examples of suitable alkali metal or alkaline earth metal hydroxide or oxide comprise LiOH, NaOH, Ca(OH)2, or MgO. Preferably, the pH adjustment comprises adding an alkali metal hydroxide, wherein the alkali metal hydroxide is NaOH. The alkali metal or alkaline earth metal hydroxide or oxide may be in the form of a solid or a liquid. For example, the dilution and pH adjustment may be carried out by diluting the stream and then adding solid alkali or alkaline earth hydroxide or oxide (e.g. NaOH), or conversely the dilution and pH adjustment may be carried out simultaneously by adding aqueous alkali or alkaline earth metal hydroxide or oxide (e.g. aqueous NaOH) to the stream.

[0084] First precipitation

[0085] The method of the disclosure comprises a first precipitation comprising a diluting and increasing the pH of a stream comprising Ni, Co and Mn sulphate in solution by at least 0.1 pH unit to a first pH of 7.5-9.0. The stream may be a feedstock stream, or it may be a stream of the liquor formed in an upstream precipitation step.

[0086] In some embodiments, the first precipitation comprises diluting and adjusting the pH of the feedstock to a first pH of 7.5-9.0.

[0087] In an alternative embodiment, the first precipitation comprises diluting and adjusting the pH of the liquor from a pre-precipitation step to a first pH of 7.5-9.0.

[0088] Preferably, the first pH is 7.5-8.5, for instance 7.6-8.8, 7.7-8.5, 7.8-8.2, or 7.8-8.0.

[0089] As demonstrated by Figure 6, the amount of metal precipitated and the selectivity of the precipitation is highly dependent on the pH and the dilution.

[0090] The amount of metal precipitated will also be dependent on the temperature at which the precipitation is carried out. Typically, a higher temperature will require harsher conditions to force precipitation e.g. higher pH or longer time. The selectivity of the precipitation step may also depend on the temperature, however Ni and Co will always precipitate at a lower pH than Mn regardless of the temperature.

[0091] Adjusting the pH to 7.5-9.0 (Figure 6) causes selective precipitation of Ni and Co from amongst Ni, Co and Mn, regardless of the dilution factor. For example, adjusting to the pH to 7.8-8.0 in the first precipitation step causes precipitation of around 98% of the Ni and Co from solution, whilst maintaining the Mn precipitation level at below 20%. The first precipitation step is therefore a selective recovery of Ni and Co. The liquor formed in the first precipitation step is therefore Mn-rich compared to the feedstock or liquor from pre-precipitation on which the first precipitation is carried out. Conversely, the liquor formed in the first precipitation step is depleted of Ni and / or Co.

[0092] The dilution of the first precipitation may be carried out using a liquid product.

[0093] The liquid product may also be partly responsible for the pH adjustment.

[0094] The pH adjustment of the first precipitation step may also be carried out by using an alkali metal or alkaline earth metal oxide or hydroxide.

[0095] Preferably, the first precipitation step is carried out using a liquid product and an alkali metal or alkaline earth metal oxide or hydroxide.

[0096] For example, the first precipitation step may be carried out using NaOH and a liquid product.

[0097] An embodiment of the disclosure relates to a method wherein the dilution of the first precipitation step is carried out using a slurry comprising the liquor and precipitates formed in the second precipitation step. In such embodiments, the slurry may be used for both dilution and at least part of the pH adjustment.

[0098] In an embodiment, the disclosure relates to a method wherein the dilution is carried out using the liquor of the second precipitation step wherein the precipitates have been removed. In such cases, the liquor is used in dilution, and a basifying agent such as an alkali metal or alkaline earth metal oxide or hydroxide is used for pH adjustment. In such embodiments, NaOH is preferably used for pH adjustment.

[0099] An embodiment of the disclosure relates to a method wherein the pH adjustment of the first precipitation step is carried out using NaOH and a slurry comprising the precipitate formed in the second precipitation step.

[0100] An embodiment of the disclosure relates to a method wherein the dilution of the first precipitation step is carried out using slurry comprising the liquor and precipitates formed in an upstream first precipitation step. The slurry may also contribute to the pH adjustment. Second precipitation

[0101] The method of the disclosure comprises a second precipitation comprising dilution and increasing the pH of the liquor of the first precipitation step by at least 0.1 pH units to a second pH of above 8.5.

[0102] The second precipitation step is carried out on the liquor of the first precipitation step. The Ni and / or Co-rich precipitate formed in the first precipitation step is optionally removed before the second precipitation step is carried out.

[0103] Whether or not the Ni and / or Co-rich precipitate is removed will depend on the reactor line set up. For instance, in a continuous or semi-continuous reactor line, the liquor from the first precipitation step may be downstream from the precipitate formed in the first precipitation, such that the pH adjustment and ensuant second precipitation step may take place without the need to physically separate the Ni and / or Co-rich precipitate from the liquor.

[0104] All that is required is that the precipitate formed in the second precipitation may be collected separately from the precipitate formed in the first precipitation step. This may be achieved in a number of ways with the appropriate set up of the production line.

[0105] Preferably, the method comprises the step of removing the Ni and / or Co oxy-rich precipitate prior to performing the second precipitation step.

[0106] By adjusting the pH to above 8.5, Ni, Co and Mn oxy compounds are precipitated. The liquor formed in the first precipitation step is Mn-rich and therefore the precipitate formed in the second precipitation is an Mn-hydroxide rich precipitate.

[0107] Preferably, the second pH is 9.0-11, such as 9.0-10.5, 9.0-10, or 9.0-9.5.

[0108] The dilution of the second precipitation may be carried out using a liquid product.

[0109] The liquid product may also be partly responsible for the pH adjustment.

[0110] The pH adjustment of the second precipitation step may also be carried out by using an alkali metal or alkaline earth metal oxide or hydroxide.

[0111] Preferably, the second precipitation step is carried out using a liquid product and an alkali metal or alkaline earth metal oxide or hydroxide. For example, the second precipitation step may be carried out using NaOH and a liquid product.

[0112] An embodiment of the disclosure relates to a method wherein the dilution of the second precipitation step is carried out using a slurry comprising the liquor and precipitates formed in an upstream second precipitation step. In such embodiments, the slurry may be used for both dilution and at least part of the pH adjustment.

[0113] An embodiment of the disclosure relates to a method wherein the dilution is carried out using the liquor of an upstream second precipitation step wherein the precipitates have been removed. In such cases, the liquor is used in dilution, and a basifying agent such as an alkali metal or alkaline earth metal oxide or hydroxide may be used for pH adjustment. In such embodiments, NaOH is preferably used for pH adjustment.

[0114] An embodiment of the disclosure relates to a method wherein the pH adjustment of the second precipitation step is carried out using NaOH and a slurry comprising the precipitates formed in an upstream second precipitation step.

[0115] In some embodiments, the pH adjustment of the second precipitation step is carried out using only NaOH.

[0116] In embodiment wherein the slurry comprising liquor and Mn oxy-rich precipitates formed in the second precipitation step is the liquid product, the second pH is 9.0-9.5.

[0117] By keeping the pH of the second precipitation step at 9.5 or below, a higher quality liquid product is obtained. At a pH of above 9.5, alkali metal and alkaline earth metals begin to precipitate for example calcium, magnesium or sodium. Accordingly, the liquid product will also comprise said alkali metal and alkaline earth metal precipitates. This leads to the downstream formation of insoluble sulphates, for example calcium or magnesium sulphate precipitates, or the formation of low value and environmentally damaging precipitates such as sodium sulphate.

[0118] Accordingly, avoiding the precipitation of alkali and alkaline earth metals in the second precipitation step is advantageous when a slurry comprising the liquor and precipitates formed in the second precipitation step are to be used as a liquid product. An embodiment of the disclosure relates to a method wherein the liquor formed in the second precipitation step comprises Li and / or an alkali metal or alkaline earth metal sulphate in solution.

[0119] Pre-precipitation

[0120] The method of the disclosure optionally comprises a pre-precipitation step. The preprecipitation step comprises diluting and increasing the pH of the feedstock stream comprising Ni, Co and Mn sulphate by at least 0.1 pH unit to a pre-precipitation pH of 7.0- 7.7.

[0121] As shown in Figure 6, increasing the pH to 7.0-7.7 causes selective precipitation of Ni and Co from amongst Ni, Co and Mn. For example, when the pre-precipitation pH is 7.2-7.4, it causes precipitation of around 40-50wt% of the Ni and Co from solution, whilst maintaining the Mn precipitation level at below 2%. The pre-precipitation step is therefore highly a selective recovery of Ni and Co.

[0122] The pre-precipitation step therefore provides a lower recovery rate of Ni and Co compared to the first precipitation step, however the selectivity of the recovery is improved. A pre- precipitation step may therefore be beneficial when the feedstock comprises a high wt% Mn, or when a high purity Ni and / or Co precipitate is desired.

[0123] As with the first precipitation step, the liquor formed in the pre-precipitation step is Mn- rich compared to the feedstock. The liquor formed in the first precipitation step is depleted of Ni and / or Co.

[0124] Preferably, the pre-precipitation pH is 7.0-7.4, such as 7.1-7.4 or 7.2-7.4.

[0125] The dilution of the pre-precipitation may be carried out using a liquid product.

[0126] The liquid product may also be partly responsible for the pH adjustment.

[0127] The pH adjustment of the pre-precipitation step may also be carried out by using an alkali metal or alkaline earth metal oxide or hydroxide.

[0128] An embodiment of the disclosure relates to a method wherein the dilution of the pre- precipitation step is carried out using a slurry comprising the liquor and precipitates formed in an upstream second precipitation step or bulk precipitation step. In such embodiments, the slurry may be used for both dilution and at least part of the pH adjustment. Preferably, the dilution and pH adjustment of the pre-precipitation step is carried out using the liquid product.

[0129] An embodiment of the disclosure relates to a method wherein the dilution is carried out using the liquor of an upstream second precipitation step wherein the precipitates have been removed. In such cases, the liquor is used in dilution, and a basifying agent such as an alkali metal or alkaline earth metal oxide or hydroxide may be used for pH adjustment. In such embodiments, NaOH is preferably used for pH adjustment.

[0130] The liquid product may be a product of the second precipitation step or the bulk precipitation step.

[0131] An embodiment of the disclosure relates to a method wherein the dilution of the preprecipitation step is carried out a slurry comprising the liquor and Mn oxy-rich precipitates formed in the second precipitation step.

[0132] An embodiment of the disclosure relates to a method wherein the dilution of the preprecipitation step is carried out using only a slurry comprising the liquor and Mn oxy-rich precipitates formed in the second precipitation.

[0133] An embodiment of the disclosure relates to a method wherein the dilution of the preprecipitation step is carried out using a slurry comprising the liquor and Ni, Co and Mn oxy precipitates formed in the bulk precipitation step.

[0134] An embodiment of the disclosure relates to a method wherein the pH adjustment of the pre-precipitation step is carried out using a liquid product only e.g. a slurry comprising the liquor and precipitates formed in the second or bulk precipitation steps.

[0135] Bulk precipitation

[0136] The method of the disclosure may comprise a bulk precipitation step. The bulk precipitation step comprises diverting at least part of a stream comprising Ni, Co and Mn sulphate in solution, and diluting and increasing the pH of the stream by at least 0.1 pH units to a bulk pH of 7.5 or above. The stream for bulk precipitation may be feedstock, or it may be a stream of the liquor formed in the pre-, first or second precipitation steps.

[0137] Preferably, the bulk precipitation is performed on a diverted stream of the feedstock. Increasing the pH of an aqueous stream comprising Ni, Co and Mn to 7.5 or above causes precipitation of Ni, Co and Mn.

[0138] Preferably, the bulk pH is 7.8 or above, 8.0 or above or 8.5 or above.

[0139] For instance, the bulk pH may be 7.5-10.0, for instance, 8.0-9.5, or 8.5-9.0.

[0140] Increasing the pH of an aqueous stream comprising Ni, Co and Mn to above 9.0 causes significant precipitation of Ni, Co and Mn. By keeping the pH at 9.0 or below, Mn precipitation is substantially avoided, which is preferred in some embodiments.

[0141] That is, preferably the bulk precipitation pH is 7.5-9.0, 7.8-9.0, 8.0-9.0 or 8.5-9.0.

[0142] The purpose of the bulk precipitation step is to provide a liquid product. In particular, the purpose of the bulk precipitation step is to the provide a liquid product that is a slurry comprising liquor and Ni, Co and / or Mn oxy precipitates. The composition of the precipitates will depend on the composition of the feedstock and the pH / dilution of the bulk precipitation step. That is, the liquid product may comprise an Ni / Co oxy rich precipitate, an Mn oxy rich precipitate or an Ni, Co and Mn oxy precipitate. The precipitates of the bulk precipitation step may be referred to as "bulk precipitates".

[0143] Preferably a slurry comprising the liquor and bulk precipitates is used to adjust the pH of a stream comprising Ni, Co and Mn sulphate in solution. An example is provided below for when the bulk precipitates are hydroxide precipitates. The example is also applicable for embodiments wherein a slurry comprising the liquor and precipitates formed in the second precipitation step is used to carry out the dilution, as it will also comprises Mn oxy precipitates.

[0144] When a slurry formed in the bulk precipitation step is combined with an aqueous stream comprising Ni, Co and Mn sulphates in solution, an exchange reaction takes place due to the relative higher solubility of MnSCk compared to Ni / CoSCk:

[0145] Ni / Co SO4 (aq) + Mn (OH)2 (s)- > Ni / Co(OH)2 (s) + Mn (SC>4) (aq)

[0146] The result is selective precipitation of Ni and Co over Mn, and also an accumulation of Mn in the solution stream. This has the knock-on effect that as the Mn-rich aqueous stream proceeds through the process, the subsequent steps also have improved separation of Ni and Co from the aqueous stream.

[0147] In addition, using a liquid product that is a slurry of the liquor and bulk precipitates also contributes to pH adjustment thereby avoiding or partially replacing the need to add a basifying agent such as an alkali metal or alkaline earth metal hydroxide. As previously discussed, sulphates of alkali metal and alkaline earth metals are undesirable and additional downstream purification steps are required. Methods wherein a liquid product of the bulk precipitation step used for dilution therefore provides an advantage over known methods.

[0148] Preferably, a slurry comprising the liquor and bulk precipitates formed in the bulk precipitation step is used to carry out the dilution of the pre- and / or first precipitation steps.

[0149] The amount of the stream diverted is preferably sufficient to produce an amount of liquid product required to carry out the pre-, first and / or second precipitation.

[0150] Preferably, the pH adjustment of the bulk precipitation step is carried out using an alkali metal or alkaline earth metal oxide or hydroxide. Preferably, the pH adjustment of the bulk precipitation step is carried out using NaOH. Even more preferably, the pH adjustment of the first precipitation step is carried out using NaOH only.

[0151] Figure 1 shows a flow diagram of the potential method pathways.

[0152] The method begins with an aqueous solution comprising Ni, Co and Mn sulphate in solution.

[0153] One embodiment relates to a method wherein a first precipitation step is performed on the aqueous solution by diluting and adjusting the pH to a first pH of 7.5-8.5. In an alternative embodiment, a pre-precipitation step is performed on the aqueous solution before performing the first precipitation step on the liquor formed in the pre-precipitation step. The two alternatives are depicted with dashed arrows.

[0154] Regardless of whether a pre-precipitation step is performed, the liquor of the first precipitation step is followed by a second precipitation by diluting and adjusting the pH of the liquor from the first precipitation step to a second pH of above 8.5, wherein the second pH is at least 0.1 pH units higher than the first pH.

[0155] In some embodiments, part of the stream of the aqueous solution is diverted for the purpose of bulk precipitation. The stream may be diverted at any point in the process. This is depicted with a dotted line.

[0156] Figure 2 shows an example of a recycling loop for the method of the disclosure.

[0157] The method comprises a first and second precipitation step along with an optional pre- precipitation step in line with the flow diagram of Figure 1. The pathway of bulk precipitation has been omitted for simplicity but may still be part of the process of Figure 2. Grey arrows depict recycling loops wherein the liquid products of the second precipitation step are used to carry out the dilution of the pre- and / or first precipitation. The dashed grey line depicts an embodiment wherein a slurry comprising the liquor and precipitates formed in the second precipitation is used as the liquid product. The solid grey line depicts an embodiment wherein the liquid product the liquor formed in the second precipitation step, wherein the precipitates have been removed. The recycling loops of the dashed and the solid grey arrows may be used individually, or they may be used in combination.

[0158] Figure 3 shows another example of a recycling loop for the method of the disclosure.

[0159] The method comprises a first and second precipitation step, along with an optional preprecipitation step in line with the flow diagram of Figure 1. The method of Figure 3 further comprises a bulk precipitation step wherein the stream is diverted at any point in order to perform a bulk precipitation of Ni, Co and Mn oxy. The solid grey arrows depict recycling loops for the liquid product of the bulk precipitation step, wherein the liquid product is a slurry comprising the liquor and precipitates formed in the bulk precipitation steps. The slurry may be used in carrying out the dilution of the pre-, first and / or second precipitation steps. The three recycling loops may be used individually, or they may be used in combination.

[0160] Figure 4 shows another example of a recycling loop for the method of the disclosure. The method comprises a first and second precipitation step, along with an optional preprecipitation step in line with the flow diagram of Figure 1. The method of Figure 4 further comprises recycling a slurry of the liquor and precipitates formed in the first precipitation step, which is used in dilution of a downstream first precipitation step or pre-precipitation step. These are represented by the dashed grey arrows. The slurry of the first precipitation step is rich in Ni / Co oxy precipitates and has a small amount of Mn oxy precipitates. When added to the aqueous stream comprising Ni, Co and Mn in solution, the Mn oxy precipitates are drawn back into solution and Ni / Co is precipitated in an exchange reaction thereby recovering more Ni / Co.

[0161] The methods of Figures 1-4 are compatible, and any combination of process steps and / or recycling loops may be used. The methods have only been separated in the flow diagram for simplicity.

[0162] In addition, each of the pathways may comprise additional dilution and / or pH adjustment steps before, between or after the pre-, first and / or second precipitation steps. For example, multiple precipitations steps at pH 7.5-8.5 may be carried out before the second precipitation step is initiated.

[0163] An embodiment of the disclosure relates to a method comprising: providing an aqueous stream comprising Ni, Co and Mn sulphate in solution; performing a first precipitation step by diluting the stream and increasing the pH of the stream by at least 0.1 pH unit to a first pH of 7.5-9.0 to form an Ni and / or Co oxy-rich precipitate and a liquor; optionally removing the Ni and / or Co oxy-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the pH of the liquor formed in the first precipitation step by at least 0.1 pH unit to a second pH of above 8.5 to form an Mn-oxy rich precipitate and a liquor; removing the Mn hydroxide-rich precipitate; wherein the dilution of the first precipitation step is carried out using the liquor formed in the second precipitation step.

[0164] In embodiments such as the foregoing, the pH adjustment of the first and second precipitation are preferably carried out using NaOH.

[0165] An embodiment of the disclosure relates to a method comprising: providing an aqueous stream comprising Ni, Co and Mn sulphate in solution; performing a first precipitation step by diluting the stream and increasing the pH of the stream by at least 0.1 pH unit to a first pH of7.5-9.0 to form an Ni and / or Co oxy-rich precipitate and a liquor; optionally removing the Ni and / or Co oxy-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the pH of the liquor formed in the first precipitation step by at least 0.1 pH unit to a second pH of above 8.5 to form an Mn-oxy rich precipitate and a liquor; removing the Mn oxy-rich precipitate; wherein the dilution of the first precipitation step is carried out using a slurry of the liquor and precipitates formed in an upstream first precipitation step. In embodiments such as the foregoing, the pH adjustment of the first and second precipitation are preferably carried out using NaOH.

[0166] An embodiment of the disclosure relates to a method comprising: providing an aqueous stream comprising Ni, Co and Mn sulphate in solution; performing a first precipitation step by diluting the stream and increasing the pH of the stream by at least 0.1 pH unit to a first pH of 7.5-9.0 to form an Ni and / or Co oxy-rich precipitate and a liquor; optionally removing the Ni and / or Co oxy-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the of the liquor formed in the first precipitation step by at least 0.1 pH unit to a second pH of above 8.5 to form an Mn-oxy rich precipitate and a liquor; removing the Mn oxy-rich precipitate; and wherein the dilution of the first precipitation step is carried out using the liquor formed in the second precipitation step, wherein the dilution is a mass dilution comprises adding 20-80 wt%, for instance 30-70wt%, of the liquor formed in the second precipitation step to the stream comprising Ni, Co and / or Mn sulphate in solution in the first precipitation step.

[0167] In embodiments such as the foregoing, the pH adjustment of the first and second precipitation are preferably carried out using NaOH.

[0168] An embodiment of the disclosure relates to a method comprising a bulk precipitation step comprising; diverting at least part of any stream comprising Ni, Co and Mn sulphate in solution; and performing a bulk precipitation step on the diverted part of the stream by diluting the stream and increasing the pH of the stream by a least 0.1 pH unit to 7.5 or above to form a bulk precipitate.

[0169] In a preferred embodiment, the disclosure relates to a method comprising a bulk precipitation step comprising; diverting at least part of any stream comprising Ni, Co and Mn sulphate in solution; and performing a bulk precipitation step on the diverted part of the stream by diluting the stream and increasing the pH of the stream by a least 0.1 pH unit to 7.5-9.0 to form a bulk precipitate.

[0170] An embodiment of the disclosure relates to a method comprising: providing an aqueous stream comprising Ni, Co and Mn sulphate in solution; performing a pre-precipitation step by diluting the stream and adjusting the pH to 7.0-7.7 to form an Ni and / or Co oxy-rich precipitate and a liquor; performing a first precipitation step by diluting a stream of the liquor formed in the pre-precipitation step and increasing the pH of the liquor formed in the preprecipitation step at least 0.1 pH unit to form an Ni and / or Co oxy-rich precipitate and a liquor, wherein the first precipitation step is carried out at a pH of 7.5-9.0; optionally removing the Ni and / or Co oxy-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the pH of the liquor formed in the first precipitation step by at least 0.1 pH unit to a second pH of above 8.5 to form an Mn-oxy rich precipitate and a liquor; wherein the method further comprises a bulk precipitation step, the bulk precipitation step comprising diverting at least part of any of the streams comprising Ni, Co and Mn sulphate in solution; and performing a bulk precipitation step on the diverted part of the stream by diluting the stream and increasing the pH of the stream by a least 0.1 pH unit to 7.5 or above to form a bulk precipitate, wherein the dilution of the pre-precipitation step is carried out using a slurry comprising the liquor and precipitates formed in the bulk precipitation step.

[0171] In embodiments such as the foregoing, preferably the stream that is diverted in the bulk precipitation step is a feedstock stream.

[0172] An embodiment of the disclosure relates to a method comprising: providing an aqueous stream comprising Ni, Co and Mn sulphate in solution; performing a pre-precipitation step by diluting the stream and increasing the pH of the stream by at least 0.1 pH unit to a pre-precipitation pH of 7.0-7.7, to form an Ni and / or Co oxy-rich precipitate and a liquor; performing a first precipitation step by diluting a stream of the liquor formed in the pre-precipitation step and increasing the pH of the liquor formed in the preprecipitation step at least 0.1 pH unit to a first pH of 7.5-9.0 to form an Ni and / or Co oxy-rich precipitate and a liquor; optionally removing the Ni and / or Co hydroxide-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the pH of the liquor formed in the first precipitation step by at least 0.1 pH unit to a second pH of above 8.5 to form an Mn-oxy rich precipitate and a liquor wherein the dilution of the pre-precipitation step is carried out using a slurry comprising the liquor and Mn oxy-rich precipitates formed in the second precipitation step.

[0173] In embodiments such as the foregoing, the pH adjustment of the first and second precipitation are preferably carried out using NaOH.

[0174] An embodiment of the disclosure relates to a comprising: providing an aqueous stream comprising Ni, Co and Mn sulphate in solution; performing a pre-precipitation step by diluting the stream and adjusting the pH to 7.0-7.7 to form an Ni and / or Co oxy-rich precipitate and a liquor; performing a first precipitation step by diluting a stream of the liquor formed in the pre-precipitation step and increasing the pH of the liquor formed in the pre- precipitation step at least 0.1 pH units to a first pH of 7.5-9.0 to form an Ni and / or Co oxy-rich precipitate and a liquor; optionally removing the Ni and / or Co oxy-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the pH of the liquor formed in the first precipitation step to a pH at least 0.1 pH units to a second pH of 9.0-9.5 to form an Mn-oxy rich precipitate and a liquor; wherein at least part of the dilution of pre-precipitation step is carried out using the liquor formed in the second precipitation step.

[0175] In embodiments such as the foregoing, the pH adjustment of the first and second precipitation are preferably carried out using NaOH. Figure 11 depicts an exemplary embodiment of the disclosure that provides optimum selectivity and resource efficiency. The dotted line represents an optional bulk precipitation step wherein the stream that is diverted in the bulk precipitation step is a stream of the liquor formed in the first precipitation step.

[0176] An embodiment of the disclosure relates to a comprising: providing an aqueous stream comprising Ni, Co and Mn sulphate in solution; performing a pre-precipitation step by diluting the stream and increasing the pH of the stream by at least 0.1 pH units to a pre-precipitation pH of 7.0-7.4 to form an Ni and / or Co oxy-rich precipitate and a liquor; performing a first precipitation step by diluting a stream of the liquor formed in the pre-precipitation step and increasing the pH of the liquor by at least 0.1 pH units to a first pH of 7.5-9.0 to form an Ni and / or Co oxy-rich precipitate and a liquor; optionally removing the Ni and / or Co oxy-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the pH of the liquor by at least 0.1 pH units to a second pH of above 8.5 to form an Mn oxy-rich precipitate and a liquor wherein the method further comprises a bulk precipitation step, the bulk precipitation step comprising diverting at least part of any of the streams comprising Ni, Co and Mn sulphate in solution; and performing a bulk precipitation step on the diverted part of the stream by diluting the stream and increasing the pH of the stream by at least 0.1 pH units to a bulk pH of above 7.5 to form a precipitate comprising Ni, Co and / or Mn oxy precipitates, wherein the dilution of the pre-precipitation step is carried out using a slurry comprising the liquor and precipitates formed in the bulk precipitation step.

[0177] An embodiment of the disclosure relates to a method comprising: providing an aqueous stream comprising Ni, Co and Mn sulphate in solution; performing a pre-precipitation step by diluting the stream and increasing the pH of the stream by at least 0.1 pH units to a pre-precipitation pH of 7.0-7.7 to form an Ni and / or Co oxy-rich precipitate and a liquor; performing a first precipitation step by diluting a stream of the liquor formed in the pre-precipitation step and increasing the pH of the liquor formed in the preprecipitation step by at least 0.1 pH units to a first pH of 7.5-9.0 to form an Ni and / or Co oxy-rich precipitate and a liquor; optionally removing the Ni and / or Co oxy-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the pH of the liquor formed in the first precipitation step by at least 0.1 pH units to a second pH of above 8.5 to form an Mn oxy-rich precipitate and a liquor wherein the dilution of the pre-precipitation step is carried out using a slurry comprising the liquor and Ni and / or Co oxy-rich precipitates formed in the first precipitation step.

[0178] In embodiments such as the foregoing, the pH adjustment of the first and second precipitation are preferably carried out using NaOH.

[0179] An embodiment of the disclosure relates to a method comprising: providing an aqueous stream comprising Ni, Co and Mn sulphate in solution; performing a pre-precipitation step by diluting the stream and increasing the pH by at least 0.1 pH units to a pre-precipitation pH of 7.0-7.7 to form an Ni and / or Co oxy-rich precipitate and a liquor; performing a first precipitation step by diluting a stream of the liquor formed in the pre-precipitation step and increasing the pH of the liquor formed in the pre- precipitation step by at least 0.1 pH units to a first pH of 7.5-9.0 to form an Ni and / or Co oxy-rich precipitate and a liquor; optionally removing the Ni and / or Co oxy-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the pH of the liquor formed in the first precipitation step by at least 0.1 pH units to a second pH of above 8.5 to form an Mn oxy-rich precipitate and a liquor wherein the method further comprises a bulk precipitation step, the bulk precipitation step comprising diverting at least part of any of the streams comprising Ni, Co and Mn sulphate in solution; and performing a bulk precipitation step on the diverted part of the stream by diluting the stream and increasing the pH of the stream by at least 0.1 pH units to a bulk pH of above 8.5 to form a precipitate comprising Ni, Co and / or Mn oxy precipitates, wherein the dilution of the pre-precipitation step is carried out using; the liquor formed in the second precipitation step, a slurry comprising the liquor and Ni and / or Co oxy-rich precipitates formed in the first precipitation step and optionally a slurry comprising the liquor and precipitates of the bulk precipitation step.

[0180] In embodiments such as the foregoing, preferably the stream that is diverted in the bulk precipitation step is a stream of the liquor formed in the first precipitation step.

[0181] In embodiments such as the foregoing, the pH adjustment of the second precipitation is preferably carried out using NaOH.

[0182] Examples

[0183] Precipitation tests were carried out to determine the effect of using a liquid product for dilution (Example 1), and pH adjustment (Example 2.1-2.2).

[0184] In the precipitation tests, the process parameters were as follows:

[0185] Temperature 55°C

[0186] Mixing speed 400-500 rpm

[0187] Time 30 min upon reaching pH set point basifying agent (Li / Na rich filtrate (Example 1), NMC oxy slurry (Examples 2.1) and Mn oxy-rich slurry (Examples 2.2) was added continuously to reach set point.

[0188] Flow diagrams of the processes are shown in Figures 5, 7 and 9 respectively. The Ni / Co / Mn oxy precipitates mainly consist of hydroxides for these examples, however other oxy precipitates may also be present.

[0189] Example 1 - dilution using liquor formed in second precipitation

[0190] Various dilutions of an aqueous stream comprising Ni, Co and Mn sulphate in solution were achieved by recirculating the liquor of a downstream second precipitation step. Precipitates of were removed from the second precipitation step before its use in dilution. The tests aimed to explore how altering the concentration of Ni, Co, and Mn in the solution, while keeping their relative ratios constant, influences the selective precipitation of Ni & Co versus Mn. In this example, NaOH was used to adjust the pH.

[0191] A flow diagram of the process is shown in Figure 5.

[0192] Compositions of the feed streams in respect to the dilution factors are presented in Table 1

[0193] Table 1. Composition of the feed streams and the dilution factors

[0194] Recycle

[0195] Test # stream Ni(+2) Co( + 2) Mn( + 2) Li( + 1) Na( + 1) mass mass % mass % mass % % mass %

[0196] 1 0.00 2.47 2.53 2.00 1.84 0.00

[0197] 2 0.33 1.60 1.64 1.36 1.79 1.76

[0198] 3 0.50 1.19 1.22 1.05 1.77 2.61

[0199] 4 0.67 0.78 0.80 0.75 1.75 3.44

[0200] The precipitation efficiencies, as a function of the solution pH for various dilution factors, are depicted in Figure 6a)-d), illustrating a decrease in the degree of precipitated manganese with an increase in the dilution factor.

[0201] Example 2 - dilution using liquid product comprising liquor and Ni / Co / Mn oxy precipitate

[0202] Three cases were investigated, differing in the choice of metal hydroxide used for the precipitation of nickel and cobalt:

[0203] 2.1 Liquor comprising Ni, Co, Mn oxy precipitate is used in dilution (liquid product of bulk precipitation)

[0204] 2.2 Liquor comprising Mn oxy-rich precipitate is used in dilution (liquid product of second precipitation)

[0205] 2.3 Liquor comprising Ni, Co oxy-rich precipitate is used in dilution (liquid product of first / second / bulk precipitation)

[0206] In all cases composition of the aqueous stream comprising Ni, Co and Mn sulphate in solution has the following composition : Ni(3.54%), Co(1.21%), Mn(1.66%), Li(1.56%), Na(1.46%). A flow diagram for the process of Example 2.1 is shown in Figure 7. A flow diagram of the process for Example 2.2 is shown in Figure 9. A flow diagram for the process of Example 2.3 is shown in Figure 11.

[0207] For all three samples, the liquid product comprises a slurry of precipitates and is therefore basic. The recycled liquid product is therefore used as both a diluent and a pH modifier for the pre-precipitation step.

[0208] Figures 8, 10 and 12 shows the Ni, Co and Mn recovery rates as a function of pH for the methods of Examples 2.1, 2.2 and 2.3 respectively.

[0209] As can be seen in all cases, the using a liquid product comprising metal precipitates is suitable for diluting and adjusting the pH of the pre-precipitation step. In all cases, the pre-precipitation step is carried out at a pH of 7.2, which is just before the point at which Mn precipitation sharply increases. The pre-precipitation step is therefore highly selective for Ni and Co.

[0210] The following first precipitation step is carried out using NaOH as a pH modifier, and in line with Example 1, shows that precipitation of Ni and Co is around 80wt% at a pH of 7.5, with precipitation Mn at less than 20wt%. The precipitation of Mn does not increase to a significant level until a pH of around 8.5 or above in both cases, which is when the second precipitation step is carried out.

Claims

1. Claims1. A method of selectively recovering Ni and / or Co from a feedstock comprising Ni, Co and Mn sulphate in solution comprising; providing a feedstock comprising Ni, Co, and Mn sulphate in solution as an aqueous stream; performing a first precipitation step by diluting the stream and increasing the pH of the stream by at least 0.1 pH units to a first pH of from 7.5 to 9.0 to form an Ni and / or Co oxy-rich precipitate and a liquor; optionally removing the Ni and / or Co oxy-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the pH by at least 0.1 pH units to a second pH of above 8.5 to form an Mn oxy-rich precipitate and a liquor; wherein at least part of a dilution is carried out using a liquid product of a precipitation step carried out at a pH higher than the pH of the feedstock.

2. A method of selectively recovering Ni and / or Co from a feedstock comprising Ni, Co and Mn sulphate in solution comprising : providing an aqueous stream comprising Ni, Co and Mn sulphate in solution; performing a pre-precipitation step by diluting the stream and increasing the pH of the stream by at least 0.1 pH units to a pre-precipitation pH of 7.0-7.7 to form an Ni and / or Co oxy-rich precipitate and a liquor; performing a first precipitation step by diluting a stream of the liquor formed in the pre-precipitation step and increasing the pH of the liquor formed in the pre- precipitation step by at least 0.1 pH units to a first pH of 7.5-9.0 to form an Ni and / or Co oxy-rich precipitate and a liquor; optionally removing the Ni and / or Co oxy-rich precipitate; and performing a second precipitation step by diluting a stream of the liquor formed in the first precipitation step and increasing the pH of the liquor formed in the first precipitation step by at least 0.1 pH units to a second pH of above 8.5 to form an Mn oxy-rich precipitate and a liquor wherein the method further comprises a bulk precipitation step, the bulk precipitation step comprising diverting at least part of any of the streams comprising Ni, Co and Mn sulphate in solution; and performing a bulk precipitation step on the diverted part of the stream by diluting the stream and increasing the pH of the diverted part of the stream byat least 0.1 pH units to a bulk pH of 7.5-9.0 to form a bulk precipitate comprising Ni, Co and / or Mn oxy precipitates, wherein the dilution of the pre-precipitation step is carried out using; the liquor formed in the second precipitation step and / or a slurry comprising the liquor and Ni and / or Co oxy-rich precipitates formed in the first precipitation step and optionally a slurry comprising the liquor and precipitates of the bulk precipitation step.

3. The method of claim 2 wherein the stream that is diverted in the bulk precipitation step is a stream of the liquor formed in the first precipitation step.

4. The method of claim 2 or 3 wherein the pH adjustment of the second precipitation is carried out using NaOH.

5. The method of any one of claims 1-4 comprising a pre-precipitation performed before the first precipitation step comprising : performing a pre-precipitation step by diluting the stream and increasing the pH of the stream by at least 0.1 pH units to a pre-precipitation pH of 7.0-7.7 to form an Ni and / or Co oxy-rich precipitate and a liquor; wherein the first precipitation step comprises diluting and increasing the pH of a stream of liquor formed in the pre-precipitation step by at least 0.1 pH units to a first pH of 7.5-9.0; and wherein the Ni and / or Co oxy-rich precipitate is optionally removed from the liquor formed in the pre-precipitation step before performing the first precipitation step.

6. The method of any one of claims 1-5 comprising a bulk precipitation step comprising: diverting at least part of any of the streams comprising Ni, Co and Mn sulphate in solution; and performing a bulk precipitation step on the diverted part of the stream by diluting the stream and increasing the pH of the stream by at least 0.1 pH units to a bulk pH of above 7.5 to form a bulk precipitate comprising Ni, Co and / or Mn oxy precipitates, preferably wherein the bulk pH is 7.5-9.0.

7. The method of claim 6 wherein the stream that is diverted is the feedstock stream or a stream of the liquor formed in a precipitation step, for instance the liquor formed in a first, second or pre-precipitation steps.

8. The method of any one of claims 1-7 wherein a dilution is carried out using the liquor of the second precipitation step wherein the method further comprises: removing the Mn oxy-rich precipitate from the liquor formed in the second precipitation step before its use in dilution.

9. The method of any one of claims 1-8 wherein the dilution of the pre- and / or first precipitation step is carried out using the liquor of a second precipitation step.

10. The method of any one of claims 1-9 wherein the dilution is a mass dilution comprising adding 20-80wt%, preferably 30-70wt%, of a liquid product to a stream comprising Ni, Co and / or Mn sulphate in solution.

11. The method of any one of claims 1-10 wherein the liquid product is a slurry comprising a liquor and Ni, Co and / or Mn oxy precipitates.

12. The method of claim 11 wherein the dilution of the pre- and / or first precipitation step is carried out using a slurry comprising the liquor and Mn oxy-rich precipitates formed in a second precipitation step.

13. The method of claim 12 wherein the second pH is 9.0 to 9.5.

14. The method of any one of claims 11-13 wherein the dilution of the pre- and / or first precipitation step is carried out using a slurry comprising the liquor and Ni, Co and Mn oxy precipitates formed in the bulk precipitation step.

15. The method of any one of claims 1-14 wherein a pH adjustment comprises adding an alkali metal or alkaline earth metal hydroxide or oxide, preferably NaOH, LiOH, (Ca(OH)2, or MgO.

16. The method of claim 15 wherein a pH adjustment comprises adding an alkali metal hydroxide, wherein the alkali metal hydroxide is NaOH.

17. The method of claim 15 or claim 16 wherein the pH adjustment of the first precipitation step, second precipitation step and / or bulk precipitation step is carried out using only an alkali metal or alkaline earth metal hydroxide or oxide.

8. The method of any one of claims 1-17 wherein the pH adjustment of the pre and / or first precipitation step is carried out using a liquid product and an alkali metal or alkaline earth metal hydroxide or oxide, wherein the liquid product is a slurry comprising a liquor and Ni, Co and / or Mn oxy precipitates.

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