CN111278997A

CN111278997A - Method for producing cobalt and related oxides from various feed materials

Info

Publication number: CN111278997A
Application number: CN201880048086.1A
Authority: CN
Inventors: 布莱恩·哈里斯; 卡尔·怀特
Original assignee: Nmr 360 Co Ltd; City Mining Co Ltd
Current assignee: Nmr 360; Nmr 360 Co Ltd; City Mining Co Ltd; Urban Mining Pty Ltd; NMR 360 Inc
Priority date: 2017-06-14
Filing date: 2018-06-08
Publication date: 2020-06-12
Also published as: EP3638819A1; WO2018227237A1; JP2020523482A; AU2018286479A1; US20200109462A1; KR20200059191A; CA3066938A1; EP3638819A4

Abstract

A process for the recovery of cobalt, nickel and manganese in oxidic form from ores, concentrates, tailings, scrap alloys and scrap batteries, which process is particularly suitable for direct use in the manufacture of lithium ion batteries. The process is unique in that it enables the recovery of cobalt, in particular, from concentrated solutions in which the ratio of nickel to cobalt is close to 1, rather than the more common 10: 1 or 1: 100. the process involves selective oxidative precipitation of each metal under conditions of different pH and ORP (oxidation reduction potential). Sodium hypochlorite is a preferred precipitant because it does not produce any acid and is therefore capable of self-buffering at a selected pH. The method is unique in that the use of Mn (VII) affects the precipitation of Mn (II).

Description

Method for producing cobalt and related oxides from various feed materials

Technical Field

The present invention relates to a process for producing cobalt and related oxides from a variety of feed materials containing primarily cobalt.

Background

The use of rechargeable lithium ion batteries has steadily increased and this increase will increase substantially as electric vehicles become more reliable and available, coupled with the increasing demand for off-peak large-scale power storage. According to various estimates, high purity cobalt will be in great shortage, especially as of 2020.

Without major cobalt mining, metals are typically recovered as a by-product of mining copper (african copper belts) or nickel (canada and laterites). In the former, the cobalt to nickel ratio in the cobalt sulphate solution obtained by leaching (leaching) the concentrate is generally about 100:1, and in the latter, the ratio of cobalt to nickel is typically 1: 10. Thus, in conventional processes, it is required to remove either a small amount of nickel from the cobalt solution or a small amount of cobalt from the nickel solution.

In addition, it is expected that the recovery of cobalt and other metals from recycled spent lithium ion batteries, similar batteries, and specialty alloys will become important, particularly for the recovery of cobalt, manganese, and nickel. However, unlike the exploitation of the byproduct sources mentioned above, the ratio of cobalt to nickel (and cobalt to manganese) is typically close to 1 (unity). Thus, each metal reflects not only the purification problem but also the major recovery opportunities, but also the separation problems. Currently, there is no process for separating all of these metals from these feedstocks in a high purity state as a valuable commodity.

Fleite S douglas in the name "hydrometallurgical separation of cobalt and nickel: review "in 2004, published in the journal" sustainable chemistry 12 ", pages 81-91, all methods for separating small amounts of cobalt from nickel or nickel from cobalt are reviewed. He concluded that the precipitation process was replaced by a solvent extraction process to remove cobalt from nickel, and that ion exchange was the only method effective for removing nickel from cobalt in a sulfate medium.

Also reviewed is an oxidative precipitation process for removing cobalt from a nickel solution in connection with the present invention. The situation is very similar for equivalent solvent extraction and ion exchange processes, and it should be noted that all of these important issues are in controlling the pH, especially if significant amounts of cobalt (i.e. close to the above 1:10 ratio) are present. It should also be noted that even strong oxidants, such as Caro's Acid (H)₂SO₅Peroxymonosulfuric acid), sometimes referred to as a super oxidant, is also generally not sufficiently effective in removing cobalt. In addition, all of these reagents generate acids, requiring the simultaneous addition of large amounts of base.

Dunne G · M, schbert · H · W and holliday · H · E describe processes using Caro's Acid and ozone as oxidative precipitation in an article entitled "nickel cobalt separation with super oxidants" (published in 1997 in journal "nickel cobalt 97", volume 1, "hydrometallurgy and refining of nickel and cobalt", edited by cooper · W · C and michilloff · I (CIM, montreal), p. 197-210). As in the flett article, it is noted that pH control is important and cobalt products containing significant amounts of nickel need to be reprocessed. It is of course that, due to the long residence time, a large amount of nickel is co-precipitated (co-precipitated).

By recycling, in particular from lithium ion batteries of various types, more particularly from so-called NMC (nickel-manganese-cobalt) batteries and alloys (such as babbitt), the ratio of cobalt to nickel is much lower than those mentioned above, often close to 1. The above mentioned oxidative precipitation methods are inadequate because they require large amounts of alkali and often co-precipitate large amounts of nickel and cobalt.

Different methods of cobalt recovery are currently being investigated, but none of them can produce a pure cobalt product that is directly suitable for battery manufacture. For example, U.S. patent US8,882,007B1 entitled "method of recovering and regenerating lithium cathode material from lithium ion batteries" filed by Retriev technologies and entitled Novis Smith W and Stevoforskott (published as 2014, 11/11) describes a method of regenerating the original lithium cathode material.

Fundamentally, the process is also a pyrometallurgical process, requiring a "low temperature" (as opposed to smelting) firing step and physical separation. Additional lithium hydroxide is then added to restore the lithium content of the recovered cathode material to its original composition. In practice, this is not a recovery method, but one of the methods to restore the original composition.

A paper entitled "selective recovery of lithium from spent lithium ion battery cathode material", published by zuoli Gutter et al (10/2016, vol 68, 10 th, p 2624-2631, published in JOM) points out a strong need to provide methods that are simpler than current metal recovery methods. A somewhat unexpected approach is to attempt to selectively recover lithium rather than the more valuable cobalt. It is achieved by using sodium persulfate under conditions of high oxidation leaching. A high recovery of lithium is obtained while suppressing the dissolution of other metal components. The high oxidation potential of sodium persulfate effectively prevents cobalt dissolution.

A method for recycling spent batteries is described in the articles Glanz Erichk, Sa Qina, Aperian Dilan and Wang Yan, entitled "closed-loop method for recycling spent lithium-ion batteries" (2014 in journal "Power 262", page 255-262). They are recovered by precipitating the mixed nickel-cobalt-manganese hydroxide and then adjusting its composition to re-produce the original battery material. This recovery has also been reported in many other articles.

A method for recovering cobalt from a leaching solution by precipitation of cobalt oxalate with oxalic acid is described in an article published by meschim parradma, pandai B D and mankand T R under the name "hydrometallurgical treatment of spent lithium ion batteries in the presence of a reducing agent focusing on the leaching kinetics" (published in 2015 in journal "chemical engineering 281", page 418 and 427). However, substantial co-precipitation of nickel oxalate occurred with a cobalt purity of about 95%. Similar methods using oxalic acid have also been reported by many other researchers.

It will be apparent from the foregoing that there is no general method or combination of methods that can be used to efficiently recover cobalt in pure form from a concentrated leach solution. It would be advantageous if such a process were available to enable the efficient recovery of cobalt and cobalt-related metals (i.e., manganese and nickel) from a variety of different feedstocks. This is important because it is expected that the supply of cobalt will be greatly in short supply in the next five years.

Accordingly, it would be desirable to provide a process for improving the recovery of cobalt while avoiding one or more of the problems of the prior art processes.

The reference to any prior art in the specification is not an acknowledgement or suggestion that prior art forms part of the common general knowledge in any jurisdiction or that prior art could reasonably be expected, but rather should be understood and regarded as relevant and/or as would be readily appreciated by a person skilled in the art in conjunction with other prior art.

Disclosure of Invention

In one aspect of the present invention, there is provided a process for recovering cobalt from an aqueous solution containing cobalt and nickel, the process comprising:

providing an aqueous solution comprising cobalt and nickel, the aqueous solution comprising cobalt and nickel having a pH of from about 4.5 to about 6.5 and an oxidation-reduction potential of from about 750 to about 900mV as measured by a Pt-Ag/AgCl electrode;

treating an aqueous solution containing cobalt and nickel with an amount of hypochlorite to oxidize and precipitate a portion of the cobalt to form a CoOOH precipitate and form a cobalt-depleted aqueous nickel solution (Co-lean Ni-aqueous solution); and

the cobalt-depleted nickel-containing aqueous solution is separated from the CoOOH.

In contrast to prior art processes, which typically recover cobalt salts in the divalent state, the above processes advantageously recover cobalt in the trivalent oxidation state. The trivalent cobalt product is of particular economic value because it eliminates further processing steps (e.g., oxidation of divalent cobalt) for applications requiring trivalent cobalt, particularly in electrochemical processes (e.g., battery operation).

In one embodiment, the aqueous solution containing Co and Ni is a chloride solution and/or a sulfate solution.

In one embodiment, Co is Co²⁺In the form of a cation. Ni is Ni²⁺In the form of a cation.

In one embodiment, the amount of hypochlorite is a sub-stoichiometric amount. Preferably, the substoichiometric amount of hypochlorite is sufficient to precipitate up to 90% of the cobalt as CoOOH. Advantageously, the inventors have found that the use of a sub-stoichiometric amount of hypochlorite provides a precipitate that is substantially pure CoOOH and substantially free of other metals. Such high purity is particularly important because many applications (e.g., in electrochemical processes) require high purity to be effective. "substantially free of other metals" is based on a comparative basis where the amount of other metals (e.g., Ni) in the precipitate is 0.5 wt% or less compared to Co (based on elemental Co). The preferred hypochlorite is NaOCl.

In embodiments where a sub-stoichiometric amount of hypochlorite is used, there remains recoverable residual cobalt in the solution. Thus, in one form of this embodiment, the method further comprises:

treating the cobalt-depleted nickel-containing aqueous solution with an amount of hypochlorite to substantially oxidize and precipitate residual cobalt in the cobalt-depleted nickel-containing aqueous solution as CoOOH and form a cobalt-depleted nickel-containing aqueous solution (Co-barren Ni-accompanying aqueous solution); and

In one embodiment, the aqueous solution containing Co and Ni has a pH of about 5.0 to about 5.5.

In one embodiment, the redox potential of the aqueous solution containing Co and Ni is about 800 to 850 mV.

In one embodiment, the step of treating the aqueous solution comprising Co and Ni is performed in less than 2 hours.

In one embodiment, the step of treating the aqueous solution comprising Co and Ni is performed for a time of at least 30 minutes.

In one embodiment, in the solution containing Co and Ni, the ratio of Co: the ratio of Ni is about 100:1 to about 1: 10. Preferably, the ratio of Co: the proportion of Ni is less than or equal to about 5.

In one embodiment, the method further comprises a Ni precipitation step comprising adding a precipitation agent to the cobalt-depleted Ni-containing aqueous solution to precipitate nickel and separating the nickel from the solution.

In one form of this embodiment, the precipitating agent is a carbonate.

In one form of this embodiment, the pH of the Co-lean Ni-containing aqueous solution is adjusted to about 7.5 to 8.5 prior to adding the precipitant.

In one form of this embodiment, the Ni precipitation step is carried out at a temperature of 45 to 80 ℃.

In one embodiment, the Co and Ni containing solution is substantially free of Cu, Fe, and Mn.

In one embodiment, the method comprises:

treating a precursor solution (precipitator solution) containing at least Mn, Co and Ni with a precipitant to selectively form a Mn precipitate; and

the Mn precipitate is separated to form an aqueous solution containing Co and Ni.

In one form of this embodiment, the pH of the precursor solution is adjusted to a value of about 3.5 to about 5.0 prior to treating the precursor solution with the precipitating agent.

In one form of this embodiment, the precipitating agent is a permanganate salt, and the permanganate salt oxidizes Mn to form MnO₂The precipitate of (4). Preferably, sufficient permanganate is added to adjust the redox potential of the precursor solution to about 700 to about 800mV, as measured by a Pt-Ag/AgCl electrode.

In one form of this embodiment, the precursor solution is treated to remove iron and copper prior to treating the precursor solution with the precipitating agent.

Other aspects of the invention and embodiments of the other aspects described in the preceding paragraphs will become apparent from the following description by way of example and with reference to the accompanying drawings.

Drawings

FIG. 1 is a process flow diagram of an embodiment of the present invention.

Figure 2 is an XRD spectrum of a solid produced according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The embodiments described in the illustrations and description are provided by way of explanation of examples of specific implementations of principles and aspects of the invention. These examples are provided to illustrate but not to limit the principles of the invention. In the following description, like parts and/or steps are marked throughout the specification and drawings with the same reference numerals.

Embodiments of the present invention will be more clearly understood with reference to the following description and fig. 1.

FIG. 1 is a schematic diagram of a method for recovering cobalt, manganese and nickel from an aqueous solution containing cobalt, nickel and manganese according to an embodiment of the present invention. Co, Ni and Mn are present in the solution in ionic form. The Co, Ni and Mn containing feed solution may be a sulphate and/or chloride based aqueous solution, in which case Co, Ni and Mn are present in the form of sulphate and/or chloride salts and are in the form of Co (ii), Ni (ii) or Mn (ii), respectively.

In this particular example, the feed solution has been pretreated to remove metal ions that may interfere with the recovery of cobalt from an aqueous solution containing cobalt, nickel and manganese, thereby forming a prepurified feed solution 10. The metal ions include at least Fe and Cu. Fe and Cu can be removed by methods known to those skilled in the art. The method includes precipitation with a base (e.g., lime), electrodeposition, solvent extraction or ion exchange. The aqueous feed solution containing Co, Ni and Mn may be subjected to additional treatment steps to remove other metal ion contaminants, if desired.

In this example, the prepurified feed solution 10 (substantially free of Fe and Cu) additionally contains Mn ions (typically in the form of Mn (ii)). The inventors have found that mn (ii) can be effectively removed in an oxidation/precipitation process involving treatment of the pre-purified feed solution 10 with permanganate.

First, the pre-purified feed solution 10 is adjusted with caustic soda 12 to raise its pH to about 3.5 to about 5.0, preferably about 4.0 to about 4.5, and most preferably about 4.2. Sodium permanganate 14 is then added to preferentially and selectively oxidize the divalent manganese in solution 10 and form a precipitate slurry 15 comprising manganese dioxide precipitate 17. To accomplish this, enough permanganate is added to adjust the oxidation-reduction potential (ORP) of the pre-purified feed solution 10 to about 700 to about 800mV (vs. Pt-Ag/AgCl electrode), preferably about 750 mV. Under these pH and ORP conditions, manganese is selectively and quantitatively recovered while avoiding the precipitation of cobalt or nickel according to the following equation (1) for the sulphate medium:

(1)3MnSO₄+2NaMnO₄→5MnO₂+H₂SO₄+Na₂SO₄

it is important to adjust the concentration of the permanganate solution, which depends on the concentration of manganese in the feed solution (see equation (1)) and to ensure that it is effectively dispersed, as it may form local areas with high ORPs which can promote the formation of cobaltous oxide (cobaltic oxide).

Sodium permanganate 14 is the preferred oxidant because it is sufficiently powerful to affect the oxidation of divalent manganese in solution. For example, hydrogen peroxide (a common oxidizing agent) does not work in this system. Potassium permanganate (a more common chemical than sodium permanganate) may also be used. However, it is more expensive to produce than sodium permanganate.

Then, the precipitate slurry 15 is subjected to solid-liquid separation 16. This may be achieved by any conventional means such as, but not limited to, flocculation (flocculation) and thickening, filter press or vacuum belt filters. The solid 17 is manganese dioxide in pure form, with a portion 19 recycled to make sodium permanganate 14. To regenerate the sodium permanganate, the solid part 19 is first fused 20 with solid caustic soda 21, and then the liquid melt 22 is quenched and cooled in water 23 to dissolve 13 and form a sodium permanganate solution 14. The sodium permanganate solution may be unstable if stored, but in this case, it should be used immediately, and thus such problems do not occur. The remaining manganese dioxide solids 18 form the product for sale.

The treated feed solution 24 from the solid-liquid separation 16 then enters a first stage 25 of cobalt precipitation, which is achieved by the addition of sodium hypochlorite 27. First, the pH of the treated feed solution 24 is adjusted to about 4.5 to about 6.5, preferably about 5.0 to about 5.5, by the addition of an alkali (e.g., caustic soda 26). The ORP is then adjusted to about 750 to about 900mV, preferably about 800 to 850mV (vs. Pt-Ag/AgCl electrode) by the addition of sodium hypochlorite 27. The inventors have found that these pH and ORP values allow for preferential and selective oxidation of cobalt (e.g. from co (ii) to co (iii)) and that cobalt precipitates as hydrocobaltite, hydrated cobaltous oxide, CoOOH. Equation (2) shows the reaction of the chloride medium:

(2)2CoCl₂+3NaOCl+H₂O₂→2CoOOH+3NaCl

sodium hypochlorite is a common chemical, commonly known as household bleach, and is a powerful oxidizing agent. However, it is rarely used in extractive metallurgy because it introduces sodium and chloride into the main sulphate-based treatment scheme. However, it has been determined that its use is particularly suitable for recovering cobalt when both the cobalt and nickel concentrations are high, as described in the present invention, because it does not generate any acid as in the processes described in the prior art and therefore does not require additional alkali, which is a major problem in conventional treatment schemes.

Nickel can also react under these conditions, which is undesirable. In view of this, the reaction with nickel is very slow, and one option to prevent nickel reaction is to limit the residence time. The inventors have found that by limiting the residence time (e.g., to less than 2 hours, preferably from about 30 to about 60 minutes), co-precipitation of nickel can be avoided, resulting in a substantially pure cobalt product (i.e., a cobalt precipitate that does not contain other metal co-precipitates). In addition, the use of a substoichiometric amount of sodium hypochlorite (sub-stoichiometric amount) relative to cobalt can also avoid co-precipitation of nickel. In this regard, a multi-stage cobalt oxidation and precipitation process may be used. For example, as shown in FIG. 1, in the first cobaltIn the precipitation stage 25, sufficient sodium hypochlorite is used to precipitate 80-90% of the cobalt to ensure that no other metals (particularly nickel) co-precipitate. The precipitation slurry 28 undergoes solid-liquid separation 29, which may be achieved by any convenient means, such as, but not limited to, flocculation and thickening, filter press or vacuum belt filter. If desired, the solid 30 may be dried to form cobaltous oxide Co₂O₃。

The solution 31 is then subjected to a second stage 32 of cobalt precipitation by the addition of an excess of sodium hypochlorite 33. This ensures that all cobalt is recovered. This may also lead to co-precipitation of small amounts of nickel. The second cobalt precipitate slurry 34 undergoes a solid-liquid separation 35, which may be achieved by any convenient means, such as but not limited to flocculation and thickening, pressure filtration or vacuum belt filters. The solids 36 are returned to the leaching (leaching) stage of the flowsheet (not shown).

The solution 37 is now substantially free of cobalt and then undergoes nickel precipitation 38. This is accomplished by adding sodium carbonate 39 at a temperature of about 45 c to about 80 c (preferably, about 60 c to about 65 c). The pH of the solution is adjusted and/or controlled to be in the range of about 7.5 to about 8.5, preferably about 8.0 to about 8.2. The precipitation slurry 40 undergoes solid-liquid separation 41, which may be achieved by any convenient means, such as, but not limited to, flocculation and thickening, filter press or vacuum belt filter. Solid 42 is pure nickel carbonate.

If the original solution is a sulfate, the solution 43 containing a mixture of sodium sulfate and sodium chloride may be recovered or simply treated, if desired, or if the original solution is a chloride, the solution 43 containing only sodium chloride may be recovered or simply treated, if desired.

The principles of the present invention are illustrated by the following examples, which are provided by way of example and should not be construed to limit the scope of the invention.

Example 1

The pH of the solution containing 80g/L Co and 20g/L Ni was adjusted to 5.5 with caustic soda, then the ORP was raised to 850mV (vs Pt-Ag/AgCl) by the addition of sodium hypochlorite. A black solid formed immediately, and after filtration, washing and air drying, the black solid was found to contain 59% Co and only 0.2% nickel, with the remainder being primarily oxygen. Fig. 2 shows XRD scans of the solid, which showed that the solid was predominantly hydrocobaltite (CoOOH) with a small amount of mixed cobaltous-nickelous trioxide.

This example demonstrates the ability of the process to recover trivalent cobalt oxide in high purity form from a solution having a high nickel content.

It will be understood that the invention disclosed and defined in the specification extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the present invention.

Claims

1. A method of recovering cobalt from an aqueous solution containing Co and Ni, the method comprising:

providing an aqueous solution comprising Co and Ni, said aqueous solution comprising Co and Ni having a pH of from about 4.5 to about 6.5 and an oxidation-reduction potential of from about 750 to about 900mV as measured with a Pt-Ag/AgCl electrode;

treating the aqueous solution containing Co and Ni with an amount of hypochlorite to oxidize and precipitate a portion of the cobalt as CoOOH and form a Co-depleted Ni aqueous solution; and

the Co-lean Ni-containing aqueous solution is separated from the CoOOH.

2. The method of claim 1, wherein the amount of hypochlorite is a sub-stoichiometric amount.

3. The method of claim 2, wherein the substoichiometric amount of hypochlorite is sufficient to precipitate up to 90% of the cobalt as CoOOH.

4. The method of claim 2, further comprising:

treating the Co-depleted Ni-bearing aqueous solution with an amount of hypochlorite to substantially oxidize and precipitate residual cobalt in the Co-depleted Ni-bearing aqueous solution as CoOOH and form a Co-depleted Ni-bearing aqueous solution; and

separating the Co-depleted Ni-containing aqueous solution from the CoOOH.

5. The method of claim 1, wherein the pH of the Co and Ni-containing aqueous solution is about 5.0 to about 5.5.

6. The method according to claim 1, wherein the redox potential of the aqueous solution containing Co and Ni is about 800-850 mV.

7. The method according to claim 1, characterized in that the step of treating the aqueous solution containing Co and Ni is carried out for a time of less than 2 hours.

8. The method according to claim 1, characterized in that the step of treating the aqueous solution containing Co and Ni is performed for a time of at least 30 minutes.

9. The method according to claim 1, wherein in the aqueous solution containing Co and Ni, Co: the ratio of Ni is about 100:1 to about 1: 10.

10. The method of claim 9, wherein the ratio of Co: the proportion of Ni is about 5 or less.

11. The process of claim 1, further comprising a Ni precipitation step comprising adding a precipitant to the Co-depleted Ni-bearing aqueous solution to precipitate nickel and separating nickel from the solution.

12. The method of claim 11, wherein the precipitant is a carbonate.

13. The method of claim 11, wherein the pH of the Co-depleted Ni-bearing aqueous solution is adjusted to about 7.5 to 8.5 prior to adding the precipitant.

14. The method according to claim 11, wherein the Ni precipitation step is performed at a temperature of 45-80 ℃.

15. The method of claim 1, wherein the aqueous solution comprising Co and Ni is substantially free of Cu, Fe, and Mn.

16. The method according to claim 1, characterized in that it comprises:

treating a precursor solution containing at least Mn, Co and Ni with a precipitant to selectively form a Mn precipitate; and

separating the Mn precipitate to form the aqueous solution containing Co and Ni.

17. The method of claim 16, wherein the pH of the precursor solution is adjusted to a value of about 3.5 to about 5.0 prior to treating the precursor solution with the precipitating agent.

18. The method of claim 16, wherein the precipitant is a permanganate and the permanganate oxidizes Mn to form MnO₂The precipitate of (4).

19. The method of claim 18, wherein sufficient permanganate is added to adjust the oxidation-reduction potential of the precursor solution to about 700 to about 800mV as measured by a Pt-Ag/AgCl electrode.

20. The method of claim 16, wherein the precursor solution is treated to remove iron and copper prior to treating the precursor solution with the precipitating agent.