CN114086003A

CN114086003A - Method for recovering nickel and cobalt from nickel and cobalt slag charge

Info

Publication number: CN114086003A
Application number: CN202111403256.3A
Authority: CN
Inventors: 班政; 唐新村; 肖莉
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2021-11-24
Filing date: 2021-11-24
Publication date: 2022-02-25

Abstract

The invention provides a method for recovering nickel and cobalt from nickel and cobalt slag, which relates to the technical field of metal recovery and mainly comprises the following steps: taking the nickel-cobalt slag obtained in the cobalt removal link in the electrolytic nickel process, and carrying out primary leaching on the nickel-cobalt slag by using an acid leaching method to obtain a primary leaching solution and a primary leaching residue; the first-stage leachate mainly contains nickel and a large amount of impurities and can be returned to the original electrolytic nickel system for uniform treatment; carrying out second-stage leaching on the first-stage leaching residue by a reduction acid leaching method to obtain a second-stage leaching solution; the secondary leaching solution mainly contains nickel and cobalt, deep impurity removal is carried out through an extraction method and the like, the content of harmful impurities is low, the recovery rate of nickel and cobalt is more than 95%, and the nickel salt, the cobalt salt and the manganese salt are correspondingly added according to the proportioning requirement of the nickel-cobalt-manganese ternary cathode material and can be used for preparing the cathode material. The invention realizes the integrated preparation from resources to materials by regulating and controlling the components of nickel and cobalt and differentially purifying impurities, simplifies the prior process flow and has higher environmental protection and economic value.

Description

Method for recovering nickel and cobalt from nickel and cobalt slag charge

Technical Field

The invention relates to the technical field of metal recovery, in particular to a method for recovering nickel and cobalt in nickel and cobalt slag.

Background

Sinkiang has abundant non-ferrous metal mineral resources, but surface water resources are deficient, the problems of land salinization and desertification are obvious, the ecological environment is very weak, the high dependence of the traditional resource utilization mode on water resources and the self-repairing capability of the environment cannot be borne on a large scale, most mineral resources are sold in the form of raw materials with low added values such as concentrate, and the resource advantages of Sinkiang are hardly brought into full play.

The traditional metallurgical technology usually separates each component in mineral resources to obtain pure chemical and metallurgical raw materials, and then recombines each component through a material preparation technology to obtain a material with high added value. The 'resource and material integration' ideal mode is provided based on the system optimization principle by Qiu crown academy of China, southern university and the like, namely, the metal or inorganic non-metal material is directly prepared from the source processing link of mineral resource mining, dressing and metallurgy, so that the aims of maximum utilization rate of mineral resources, minimum energy consumption and minimum environmental burden are fulfilled.

Taking copper-nickel ore in Xinjiang as an example, cobalt in the leachate of the copper-nickel ore generates about 2000 tons of nickel-cobalt slag every year after being oxidized and precipitated by NiOOH (black nickel). In order to recover nickel and cobalt in nickel-cobalt slag, a cobalt workshop is arranged in a certain smelting group in Xinjiang to process the slag, and the slag is subjected to a series of complicated deep impurity removal processes such as copper removal, iron removal, zinc removal, lead removal and the like and a series of complicated and high-energy-consumption processes such as repeated pH value adjustment, nickel-cobalt extraction separation, electrolysis and the like, so that electrolytic cobalt and electrolytic nickel products are finally obtained. Meanwhile, the group is also provided with a production line of the nickel-cobalt-manganese ternary cathode material for the lithium ion battery, and the required nickel salt, cobalt salt and manganese salt are purchased according to market price. The group uses the cost consumption of a whole cobalt workshop to realize the separation of nickel and cobalt to obtain electrolytic nickel and electrolytic cobalt products, however, the preparation production line of the nickel-cobalt-manganese ternary cathode material for the lithium ion battery needs to mix the separated nickel and cobalt. Obviously, the space for system optimization over the overall configuration of the process is very large.

In view of the above problems, there is a need to provide a method for recovering nickel and cobalt from nickel and cobalt slag, so that nickel and cobalt can be efficiently recovered and directly used for preparing a nickel-cobalt-manganese ternary cathode material, thereby achieving the purpose of realizing clean and high-value utilization of nickel and cobalt resources in Xinjiang.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a method for recovering nickel and cobalt from nickel and cobalt slag, and aims to solve the problems that the impurity removal process in the nickel and cobalt recovery process is complex and tedious, the energy consumption is high, and the nickel and cobalt recovery process and the nickel and cobalt manganese ternary cathode material preparation process are disjointed.

In order to achieve the aim, the invention provides a method for recovering nickel and cobalt from nickel and cobalt slag, which adopts the technical scheme that the method comprises the following steps:

(1) taking the nickel-cobalt slag obtained in the cobalt removal link in the electrolytic nickel process flow, carrying out primary leaching on the nickel-cobalt slag by using an acid leaching method, controlling the pH value of the acid leaching end point to be 2-4, and stirring and filtering to obtain a primary leaching solution and a primary leaching residue;

(2) returning the first-stage leaching solution obtained in the step (1) to an original electrolytic nickel system, and uniformly treating the first-stage leaching solution and an original nickel solution;

(3) and (2) carrying out secondary leaching on the primary leaching residue obtained in the step (1) by using a reduction acid leaching method, and completely dissolving the primary leaching residue after reacting for 1-3h to obtain a secondary leaching solution.

(4) And (4) deeply removing impurities from the second-stage leaching solution obtained in the step (3) by using extraction method and other methods to obtain nickel-cobalt purified solution with low impurity content.

Further, the nickel-cobalt slag in the step (1) refers to slag obtained by removing cobalt from black Nickel (NiOOH) in an electrolytic nickel process flow; wherein the nickel coexists in divalent and trivalent forms, the content is 38-44%, the cobalt exists mainly in trivalent form, the content is 6-8%, and the content ratio of nickel to cobalt is 6:1-7: 1.

Further, the acid leaching method in the step (1) specifically comprises the steps of placing the nickel cobalt slag material in a beaker, adding pure water and sulfuric acid, and stirring and leaching; wherein the sulfuric acid is 98 wt% concentrated sulfuric acid, the reaction temperature is normal temperature, and the reaction time is 0.5-2h until the pH value of the feed liquid reaches the required value.

Further, the first-stage leachate in the step (1) is a leachate with high nickel, low cobalt and high impurity content, and the obtained first-stage leachate enters the step (2).

Further, the first-stage leaching slag in the step (1) is specifically nickel-cobalt leaching slag with low impurity content; wherein, both nickel and cobalt exist mainly in trivalent form, and the content ratio of nickel to cobalt is 1:1-2: 1; and (4) feeding the obtained first-stage leaching residue into the step (3).

And (3) further, returning the acid leaching solution in the step (2) to the original electrolytic nickel system, and performing unified processes of impurity removal, purification and the like to produce and prepare electrolytic nickel.

Further, the reduction leaching method in the step (3) is specifically to put the first-stage acid leaching residue into a flask, add a reducing agent and a sulfuric acid solution, and stir-leach; wherein the reducing agent is 30 wt% of hydrogen peroxide, the sulfuric acid is 98 wt% of concentrated sulfuric acid, and the obtained two-stage leaching solution enters the step (4).

Further, in the step (3), the reaction temperature is 50-80 ℃, the concentration of sulfuric acid is 1-2mol/L, the dosage of a reducing agent is 1-2mL/g, and the liquid-solid ratio is 5:1-10:1 until the first-stage leaching residue is completely dissolved.

Further, the extraction method in the step (4) is specifically to separate and recycle impurities from the secondary leaching solution by using an extractant to obtain nickel-cobalt purification solution with low impurity content; wherein the extractant is P204.

Further, in the step (4), the concentration of the extracting agent is 10-20%, the saponification rate is 20-60%, the pH value of the water phase is 3-4, and the ratio of O/A is 1-1.5.

Further, the nickel-cobalt purification solution with low impurity content in the step (4) can be added with nickel salt, cobalt salt and manganese salt according to the proportioning requirement of the nickel-cobalt-manganese ternary cathode material, and the nickel-cobalt purification solution is used for preparing and producing the nickel-cobalt-manganese ternary cathode material after the proportioning is balanced.

Aiming at the efficient recycling of nickel-cobalt slag generated in the impurity removal process of an electrolytic nickel system, the slag mainly contains nickel, cobalt, copper, magnesium and other impurity ions, wherein the content of nickel is 38-44%, and the content of cobalt is 6-8%.

Compared with the prior art, the scheme of the invention has the following beneficial effects:

(1) the invention creatively uses a two-stage leaching method based on the performance difference of nickel and cobalt ions under different valence states to obtain leaching solution with high nickel content, low cobalt content and high impurity content and nickel-cobalt solution with low impurity content. The leaching solution in the first section can be directly returned to the original electrolytic nickel system for uniform treatment due to higher nickel content and relatively more impurity content, an additional impurity removal procedure is not required, and the recycling of nickel can be realized without greatly improving the recycling cost due to the fact that the solution amount is far less than the nickel solution amount of the electrolytic nickel system. After the first-stage leaching, the impurity content in the second-stage nickel-cobalt solution is relatively low, and the impurity is simply removed or not removed according to the actual content of impurity ions, so that the nickel-cobalt-manganese ternary cathode material can be used for preparation and production of the nickel-cobalt-manganese ternary cathode material, the impurity removal process is simplified, and the cost is greatly reduced.

(2) The nickel-cobalt content ratio of the nickel-cobalt slag used in the invention is 6:1-7:1, and in the first-stage leaching process, a large amount of nickel is leached out, while cobalt is not leached out basically, so that the nickel-cobalt content ratio in the second-stage leaching solution is reduced to 1:1-2: 1. Because the content ratio of nickel and cobalt in the nickel-cobalt-manganese ternary cathode material in the market is mainly 1:1, the requirement for preparing the nickel-cobalt-manganese ternary cathode material can be met by only adding a small amount of cobalt salt into the second-stage leaching solution. Considering that the market price of cobalt salt is expensive, the invention not only saves the cost, but also solves the important problem of nickel-cobalt mixture ratio balance in the process flow.

(3) The invention adopts the idea of 'integration of resources and materials', and nickel and cobalt are not separated in the nickel-cobalt recovery process, but coexist in the solution and are directly used for preparing the nickel-cobalt-manganese ternary cathode material. Meanwhile, relevant researches show that proper amount of metal ions (such as aluminum, magnesium and the like) doped in the nickel-cobalt-manganese ternary cathode material is beneficial to the electrochemical performance of the lithium ion battery. Therefore, in the impurity removal process, not all impurity elements need to be deeply purified by a complicated separation and purification process, only harmful impurities need to be deeply removed, and beneficial impurities can be retained in the solution together with nickel and cobalt after being reasonably purified for the subsequent preparation of the nickel-cobalt-manganese ternary cathode material. The differential purification not only simplifies the separation and purification process, but also has beneficial effects on the structure and the performance of the subsequent preparation of the anode material.

Drawings

Fig. 1 is a schematic flow chart of a method for recycling nickel and cobalt from nickel and cobalt slag in an embodiment of the invention.

Detailed description of the invention

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following detailed description is made with reference to specific drawings and embodiments. The description is to be regarded as illustrative and explanatory only and should not be taken as limiting the scope of the invention in any way. Furthermore, those skilled in the art can combine features from the embodiments of this document and from different embodiments accordingly based on the description of this document.

Examples

A method for recovering nickel and cobalt in nickel and cobalt slag comprises the following steps:

(1) taking a nickel-cobalt slag material obtained in a cobalt removal link in a nickel electrolysis process flow of a certain smelting group in Xinjiang, adding a sulfuric acid solution at normal temperature to carry out primary leaching on the nickel-cobalt slag material, controlling the pH value of an acid leaching end point to be 2.5, reacting for 1h, stirring and filtering for a while to obtain a primary leaching solution and a primary leaching residue; the contents of elements in the nickel-cobalt slag material, the first-stage leaching slag and the first-stage leaching liquid sample are detected by adopting an Inductively Coupled Plasma (ICP) spectrometer, and the obtained results are shown in the following table:

as can be seen from the table, most of nickel and a large amount of impurities in the nickel-cobalt slag are dissolved and leached in the first-stage leaching solution, while the cobalt is hardly dissolved and remains in the first-stage leaching residue; the content ratio of nickel and cobalt in the nickel and cobalt slag is about 6:1, and the content ratio of nickel and cobalt in the first-stage leached slag is reduced to 1.5: 1. The experimental result shows that the proportion of nickel and cobalt is close to balance, and the primary separation of impurities is realized.

(2) And (2) adding a sulfuric acid solution and a hydrogen peroxide solution into the first-stage leaching residue obtained in the step (1) for second-stage leaching, wherein the sulfuric acid concentration is 1.5mol/L, the hydrogen peroxide concentration is 2.0mL/g, the liquid-solid ratio is 10:1, reacting for 2 hours at 60 ℃, and dissolving the first-stage leaching residue to obtain a second-stage leaching solution. The ICP (inductively coupled plasma spectrometer) is adopted to detect the element content in the two-stage leaching solution sample, and the obtained results are shown in the following table:

it can be seen from the table that the leaching rates of nickel and cobalt in the two-stage leachate are 99.56% and 99.40%, respectively, and are almost completely dissolved, the content ratio of nickel and cobalt is about 1.5:1, and the content of impurity ions in the two-stage leachate is obviously reduced compared with that in the first-stage leachate.

(3) And (3) adding the second-stage leachate obtained in the step (2) into a P204 organic phase for deep impurity removal, wherein the concentration of an extracting agent is 10%, the saponification rate is 50%, the pH value of a water phase is 3.5, and the ratio of O/A to O/A is 1.2, so that the nickel-cobalt purification solution with low impurity content is obtained. The ICP (inductively coupled plasma spectrometer) is adopted to detect the element content in the nickel cobalt purification liquid, and the obtained results are shown in the following table:

as can be seen from the table, the direct recovery rates of nickel and cobalt in the nickel and cobalt purification solution are 95.04% and 94.22%, and meanwhile, the impurity content is further reduced compared with the second-stage leachate, and only magnesium ions in the impurities have relatively high content, so that considering that the doping of a small amount of magnesium ions has beneficial effects on the structure and performance of the nickel and cobalt manganese ternary cathode material, continuous impurity removal is not needed, the solution meets the requirements for preparing the nickel and cobalt manganese ternary cathode material, and the nickel and cobalt manganese ternary cathode material can be prepared by a method of adding nickel salt, cobalt salt and manganese salt.

The experimental result shows that after the steps, the nickel-cobalt solution is deeply purified, the content of impurity ions is lower, the content of nickel and cobalt is closer to the requirement of preparing the nickel-cobalt-manganese ternary cathode material than the content of the original nickel-cobalt slag material, only a small amount of cobalt salt and manganese salt needs to be added, the proportion of the content of nickel, cobalt and manganese in the solution can meet the requirement, and the solution is directly used for preparing the nickel-cobalt-manganese ternary cathode material.

The invention greatly simplifies and improves the recycling mode of nickel cobalt resources, and has very obvious environmental protection benefit and economic benefit.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for recovering nickel and cobalt in nickel and cobalt slag is characterized by comprising the following steps:

(4) And (4) deeply removing impurities from the second-stage leaching solution obtained in the step (3) by using methods such as an extraction method and the like to obtain the nickel-cobalt purifying solution with low impurity content.

2. The recycling method according to claim 1, wherein the nickel cobalt slag in step (1) is slag obtained by removing cobalt from black Nickel (NiOOH) in an electrolytic nickel process flow; wherein the nickel coexists in divalent and trivalent forms, the content is 38-44%, the cobalt exists mainly in trivalent form, the content is 6-8%, and the content ratio of nickel to cobalt is 6:1-7: 1.

3. The recycling method according to claim 1, wherein the acid leaching method in the step (1) is specifically to put the nickel cobalt slag charge into a beaker, add pure water and sulfuric acid for agitation leaching; wherein the sulfuric acid is 98 wt% concentrated sulfuric acid, the reaction temperature is normal temperature, and the reaction time is 0.5-2h until the pH value of the feed liquid reaches the required value.

4. A recovery process according to claim 1, wherein the first leach solution from step (1) is a high nickel, low cobalt, high impurity leach solution, and the first leach solution is passed to step (2).

5. The recycling method according to claim 1, wherein the first stage leached slag in the step (1) is nickel cobalt leached slag with low impurity content; wherein, both nickel and cobalt exist mainly in trivalent form, and the content ratio of nickel to cobalt is 1:1-2: 1; and (4) feeding the obtained first-stage leaching residue into the step (3).

6. The recovery method according to claim 1, wherein the pickle liquor in the first stage in the step (2) is returned to the original electrolytic nickel system, and is used for producing and preparing electrolytic nickel through processes of unified impurity removal, purification and the like.

7. The recovery method according to claim 1, characterized in that the reduction leaching method in the step (3) is specifically to put a section of acid leaching residue into a flask, add a reducing agent and a sulfuric acid solution, and stir-leach; wherein the reducing agent is 30 wt% of hydrogen peroxide, the sulfuric acid is 98 wt% of concentrated sulfuric acid, and the obtained two-stage leaching solution enters the step (4).

8. The recycling method according to claim 1, wherein in the step (3), the reaction temperature is 50-80 ℃, the sulfuric acid concentration is 1-2mol/L, the dosage of the reducing agent is 1-2mL/g, and the liquid-solid ratio is 5:1-10:1 until the first-stage leaching residue is completely dissolved.

9. The recovery method according to claim 1, wherein the extraction method in the step (4) is specifically to separate and recover impurities from the secondary leaching solution by using an extractant, so as to obtain a nickel-cobalt purification solution with low impurity content; wherein the extractant is P204.

10. The recovery method according to claim 1, wherein the concentration of the extractant in the step (4) is 10% to 20%, the saponification rate is 40% to 60%, the pH of the aqueous phase is 3 to 4, and the phase ratio O/A is 1 to 1.5.

11. The recycling method according to claim 1, wherein the nickel cobalt purified liquid with low impurity content in the step (4) can be added with nickel salt, cobalt salt and manganese salt according to the proportioning requirement of the nickel cobalt manganese ternary cathode material, and the mixture is used for preparing the nickel cobalt manganese ternary cathode material after the proportioning is balanced.