Leaching method of waste ternary lithium battery positive electrode material

Abstract

The invention discloses a leaching method of a waste ternary lithium battery positive electrode material, and relates to the field of hydrometallurgy, the leaching method comprises the following steps: taking the positive electrode material, carrying out first pulpifying, then carrying out acid leaching, and carrying out solid-liquid separation to obtain primary leaching residues and a lithium-containing ternary leaching solution; the primary leaching residues are subjected to secondary pulpifying and then mixed with alkali liquor to neutralize residual acid on the surfaces of the primary leaching residues, and secondary leaching residues and neutralized liquid are obtained through solid-liquid separation; and carrying out reduction roasting on the secondary leaching residues, mixing the secondary leaching residues with the neutralized liquid, carrying out third-time slurrying to obtain a slurrying material, carrying out reduction acid leaching on the slurrying material to obtain a leaching solution, repeating the steps on a subsequent batch of positive electrode materials, and recycling the subsequent batch of lithium-containing ternary leaching solution. According to the application, through a combined process of wet leaching, pyrogenic reduction and wet leaching, the volume of a required hearth furnace and the dosage of a reducing agent are reduced under the condition that the occupied space of wet leaching is not increased.

Description

Technical Field

[0001] The present application relates to the field of hydrometallurgy, and in particular to a method for leaching waste ternary lithium battery positive electrode materials. Background Art

[0002] In the current leaching process of positive electrode materials for ternary lithium batteries, there are two routes: full leaching and selective leaching. The full leaching scheme is further divided into two leaching schemes: full wet leaching and a combination of pyrometallurgy and wet leaching. Among them, the full wet leaching has problems such as large amount of reducing agent used and low reduction efficiency. The pyrometallurgy-wet leaching scheme currently all involves first placing the waste positive electrode material in a chamber furnace for pyrometallurgical reduction, and then performing wet leaching to remove impurities to obtain the required material.

[0003] In the current pyrolysis reduction followed by wet leaching route, since all materials need to be reduced and roasted, the required furnace volume is large. The larger the furnace, the more difficult it is to seal, which poses a safety hazard. At the same time, the amount of reducing agent used will also increase accordingly. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned related technologies, the present application provides a method for leaching the positive electrode material of waste ternary lithium batteries. The present application uses a combined process of wet leaching-pyrometallurgical reduction-wet leaching to firstly leach the positive divalent nickel ions that are easily acid-leached, thereby reducing the volume of the waste ternary lithium battery positive electrode material that needs to be pyrometallurgically reduced, thereby reducing the volume of the required chamber furnace and saving the reducing agent.

[0005] The present application provides a method for leaching anode materials of waste ternary lithium batteries using the following technical solution: A method for leaching waste ternary lithium battery positive electrode materials comprises the following steps: taking the positive electrode material for the first slurrying and then acid leaching, solid-liquid separation to obtain primary leaching residue and lithium-containing ternary leaching solution; slurrying the primary leaching residue for the second time and mixing with alkali solution to neutralize the residual acid on the surface of the primary leaching residue, solid-liquid separation to obtain secondary leaching residue and neutralized liquid; reducing roasting the secondary leaching residue to obtain roasted material, mixing the roasted material with the neutralized liquid for the third slurrying to obtain a third slurry material, reducing acid leaching the third slurry to obtain a leaching solution, repeating the above steps for subsequent batches of positive electrode materials, wherein the leaching solution is used for slurrying in the processing process of the next batch of positive electrode materials, and the subsequent batches of lithium-containing ternary leaching solution are recycled.

[0006] Preferably, the solid-liquid ratio of the first slurrying is 1:3-5.

[0007] Preferably, the acid leaching is controlled at a pH of 1.0-2.0, a temperature of 50-60° C., and a reaction time of 2-3 h.

[0008] Preferably, the solid-to-liquid ratio of the second slurrying is 1:1-2.

[0009] Preferably, the reduction roasting comprises the following steps: mixing the secondary leaching slag with the first reducing agent, placing the mixture in an inert gas atmosphere, heating the mixture to 550-650° C., roasting the mixture at a constant temperature for 2-4 hours, and then naturally cooling the mixture to room temperature.

[0010] Preferably, the weight ratio of the first reducing agent to the secondary leaching residue is 1-2:100.

[0011] Preferably, the first reducing agent includes one or more of carbon powder, carbon monoxide and hydrogen.

[0012] Preferably, the first reducing agent is carbon powder.

[0013] In the present application, carbon powder is used as the first reducing agent because carbon powder is the safest compared to carbon monoxide and hydrogen.

[0014] Preferably, the reducing acid leaching comprises the following steps: adding acid to the slurry to control the acidity to 0.8-1.2 mol / L, and then adding a second reducing agent until the slurry is clear.

[0015] Preferably, the second reducing agent includes one or more of hydrogen peroxide, sodium pyrosulfite and sodium sulfite.

[0016] Preferably, the second reducing agent is hydrogen peroxide.

[0017] Preferably, the alkali solution comprises 20%-50% by mass of sodium hydroxide solution.

[0018] Preferably, the alkali solution comprises 32% by mass of sodium hydroxide solution.

[0019] In summary, the present application includes at least one of the following beneficial technical effects: 1. This application adopts a combined process of wet leaching-fire reduction-wet leaching. Since the ternary positive electrode material can be LiMeO2, where Me is Ni x Co y Mn （1-x-y） Among them, Ni is mainly in +2 valence, Co and Mn are in +3 / +4 valence, Ni is mainly low valence, most of it can be leached in the conventional leaching process, Co and Mn need to be leached in the presence of a reducing agent, so the divalent nickel ions that are easy to acid-leach are leached, which reduces the volume of the waste ternary lithium battery positive electrode material that needs to be reduced by pyrolysis, thereby reducing the volume of the required hearth furnace. Compared with the process of reduction roasting and then acid leaching, the required volume of the hearth furnace is reduced by 70%, saving more than half of the hearth furnace volume and hearth furnace investment, and also reducing safety hazards.

[0020] 2. The present application adopts a combined process of wet leaching-fire reduction-wet leaching. Since some negative electrode powder, namely carbon powder, will be entrained in the positive electrode material of the waste ternary lithium battery, and the carbon powder does not react in the wet leaching, it will enter the primary leaching residue and can act as a reducing agent in the fire reduction, thereby saving the amount of reducing agent and reducing the cost of the reducing agent.

[0021] 3. In the present application, the neutralized liquid is used for the slurrying of the secondary leaching residue, and the leaching liquid is used for the first slurrying of the next batch of positive electrode materials. The leaching liquid is acidic, which can further save the amount of acid used for acid leaching in the next batch of positive electrode materials, save water resources, and help improve the recovery and utilization rate of lithium, cobalt, nickel, and manganese elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the process flow chart of this application. DETAILED DESCRIPTION

[0023] The present application is further described in detail below in conjunction with examples. The following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. In the following examples, if specific conditions are not specified, they are carried out according to normal conditions or conditions recommended by the manufacturer. The methods used are conventional methods known in the art unless otherwise specified, and the consumables and reagents used are commercially available unless otherwise specified. Unless otherwise specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the recorded content may also be applied to the present invention.

[0024] The embodiment of the present application provides a method for leaching positive electrode materials of waste ternary lithium batteries.

[0025] A method for leaching the positive electrode material of waste ternary lithium battery, referring to Figure 1 , the specific steps are as follows: Slurrying of waste ternary lithium battery positive electrode materials (black powder materials): adding tap water and the leaching solution obtained from the previous batch into the waste ternary lithium battery positive electrode materials in a solid-liquid ratio of 1:4 to perform the first slurrying of the waste ternary lithium battery positive electrode materials to obtain the first slurry material.

[0026] Leaching of waste ternary lithium battery positive electrode materials: Add 98% sulfuric acid to the first slurry, adjust the pH to 1.0-2.0, control the temperature to 55°C, and react for 2.5 hours. Leaching the divalent nickel ions that are easily acid-leached reduces the volume of waste ternary lithium battery positive electrode materials that need to be pyrolyzed, thereby reducing the volume of the required chamber furnace.

[0027] Primary filtration: Use a filter press to filter the leached material to obtain a ternary leaching solution containing lithium, cobalt, nickel and manganese and a primary leaching residue.

[0028] Slurrying the primary leaching residue: adding tap water to the primary leaching residue in a solid-liquid ratio of 1:1.5 to slurry the primary leaching residue to obtain a second slurry.

[0029] Neutralization of primary leaching residue: Add 32% liquid alkali (32% by mass sodium hydroxide solution) to the second slurry to pH = 6-7, so as to neutralize the residual acid carried on the surface of the primary leaching residue.

[0030] Secondary filtration: Use a filter press to filter the neutralized primary leaching residue to obtain secondary leaching residue and neutralized liquid.

[0031] Reduction roasting: Add carbon powder equivalent to 1.5% of its own weight as the first reducing agent to the secondary leaching slag for reduction roasting in a hearth furnace. The roasting is carried out in a nitrogen atmosphere. The roasting temperature program is 5℃ / min to 600℃, then the temperature is kept constant for 3h, and then naturally cooled to room temperature to obtain the roasted material. The positive electrode material of the waste ternary lithium battery will contain some negative electrode powder, namely carbon powder, which does not react in the previous step and acts as a reducing agent in this step, thereby saving the amount of reducing agent and reducing the cost of reducing agent.

[0032] Slurrying the calcined material: adding the neutralized liquid to the calcined material. In this process, the slurry ratio is not controlled to obtain the third slurry.

[0033] Leaching of the calcined material: adding 98% sulfuric acid to the third slurry to control the acidity to 1 mol / L, and then adding hydrogen peroxide as a second reducing agent until the third slurry is clear and bright, to obtain a leachate, which is used for slurrying the waste ternary lithium battery positive electrode material in the first slurrying process of the next batch of waste ternary lithium battery positive electrode material, thereby further saving the amount of acid used for acid leaching in the next batch of waste ternary lithium battery positive electrode material.

[0034] The implementation principle of a leaching method for positive electrode materials of waste ternary lithium batteries in an embodiment of the present application is as follows: neutralize the positive electrode materials of waste ternary lithium batteries after acid leaching, add carbon powder as the first reducing agent to the obtained secondary leaching slag and perform reduction roasting in a hearth furnace, and finally perform reduction acid leaching on the roasted material. The combined process of wet leaching-fire reduction-wet leaching can leach divalent nickel ions that are easily leached by acid, thereby reducing the volume of the positive electrode materials of waste ternary lithium batteries that need to be reduced by fire, thereby reducing the volume of the required hearth furnace. Since some negative electrode powder, namely carbon powder, will be entrained in the positive electrode materials of waste ternary lithium batteries, and the carbon powder does not react in wet leaching, it will enter the primary leaching slag and can act as a reducing agent in fire reduction, thereby saving the amount of reducing agent and reducing the cost of reducing agent.

[0035] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for leaching waste ternary lithium battery positive electrode materials, characterized in that: The following steps are involved: The positive electrode material is pulped for the first time and then acid leached, and solid-liquid separation is performed to obtain a primary leaching residue and a lithium-containing ternary leaching solution; the primary leaching residue is pulped for the second time and mixed with an alkali solution to neutralize the residual acid on the surface of the primary leaching residue, and solid-liquid separation is performed to obtain a secondary leaching residue and a neutralized liquid; the secondary leaching residue is reduction roasted to obtain a roasted material, the roasted material is mixed with the neutralized liquid and pulped for the third time to obtain a third pulped material, and the third pulped material is subjected to reduction acid leaching to obtain a leachate, and the above steps are repeated for subsequent batches of positive electrode materials, wherein the leachate is used for pulping in the processing process of the next batch of positive electrode materials, and the subsequent batches of lithium-containing ternary leaching solutions are recycled.

2. The method for leaching anode materials of waste ternary lithium batteries according to claim 1, characterized in that: The solid-liquid ratio of the first slurrying is 1:3-5.

3. The leaching method of a waste ternary lithium battery positive electrode material according to claim 1, characterized in that: The acid leaching is controlled at a pH of 1.0-2.0, a temperature of 50-60° C., and a reaction time of 2-3 hours.

4. The method for leaching anode materials of waste ternary lithium batteries according to claim 1, characterized in that: The solid-liquid ratio of the second slurrying is 1:1-2.

5. The method for leaching anode materials of waste ternary lithium batteries according to claim 1, characterized in that: The reduction roasting comprises the following steps: mixing the secondary leaching slag with the first reducing agent, placing the mixture in an inert gas atmosphere, heating the mixture to 550-650° C., roasting the mixture at a constant temperature for 2-4 hours, and then naturally cooling the mixture to room temperature.

6. The method for leaching the positive electrode material of waste ternary lithium batteries according to claim 5, characterized in that: The weight ratio of the first reducing agent to the secondary leaching residue is 1-2:

100.

7. The method for leaching the positive electrode material of waste ternary lithium batteries according to claim 5, characterized in that: The first reducing agent includes one or more of carbon powder, carbon monoxide and hydrogen.

8. The method for leaching anode materials of waste ternary lithium batteries according to claim 1, characterized in that: The reducing acid leaching comprises the following steps: adding acid to the slurry to control the acidity to 0.8-1.2 mol / L, and then adding a second reducing agent until the slurry is clear.

9. The method for leaching the positive electrode material of waste ternary lithium batteries according to claim 8, characterized in that: The second reducing agent includes one or more of hydrogen peroxide, sodium pyrosulfite and sodium sulfite.

10. The method for leaching the positive electrode material of waste ternary lithium batteries according to claim 1, characterized in that: The alkali solution comprises 20%-50% by mass of sodium hydroxide solution.

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