Method for recovering valuable metal elements from waste lithium ion batteries by using mechanical activation method

Abstract

A method for recovering valuable metal elements from a waste lithium ion battery by using a mechanical activation method comprises the following steps: (1) carrying out ball milling on a positive electrode active material of the waste lithium ion battery and a sulfur source to obtain an activated product; and (2) the activated product is subjected to acid leaching, and sulfur-containing filter residues and a solution containing valuable metal are obtained. Through mechanical ball milling, transition metal elements in the waste lithium ion battery positive electrode material can be effectively reduced during ball milling, the use of a reducing agent is reduced, the reaction rate is obviously increased after activation, the valuable metal recovery rate is high, and the use of an acid solution can be reduced.

Description

Technical Field

[0001] The invention relates to resource recycling of waste lithium-ion batteries, and in particular to a method for recycling valuable metal elements from waste lithium-ion batteries by using a mechanical activation method. Background Art

[0002] Lithium-ion batteries have been widely used in new energy vehicles, mobile phones, computers and other fields in recent years due to their high operating voltage, high energy density and no memory effect. The sales of lithium-ion batteries have increased dramatically. When lithium-ion batteries reach the end of their service life, they will be retired explosively. With the coming of the retirement period of power batteries and the constraints of lithium resources, lithium battery recycling is imperative. Under the background of carbon neutrality, the electric vehicle and energy storage markets will grow rapidly. There is a shortage of metal resources such as lithium, nickel, cobalt, and manganese in lithium-ion batteries, and it is also necessary to recycle the valuable metals in waste lithium-ion batteries to alleviate the current situation of resource shortage.

[0003] The current mainstream recycling process is to discharge, disassemble and crush waste lithium-ion batteries to obtain active materials, and then subject the active materials to acid leaching, neutralization and impurity removal, filtration, extraction, lithium precipitation, washing, drying, etc. The process is long and requires the addition of additional reducing agents to increase costs. Currently, mechanochemical methods are used to treat waste lithium-ion battery positive electrode materials. Although the leaching rate of valuable metals is high, a large amount of reducing agents and activating agents need to be added, and the cost is very high. Therefore, it is necessary to develop a recycling method with low cost and fast leaching rate.

[0004] Patent document with publication number CN107275706A discloses a method of activating a lithium cobalt oxide material in a planetary ball mill, leaching the activated lithium cobalt oxide positive electrode material in an ascorbic acid solution at room temperature, and extracting lithium and cobalt by conventional methods such as electrodeposition after solid-liquid separation. This method adds ascorbic acid, which has a high cost of reducing acid, and the cost of treating complex positive electrode materials such as ternary materials is higher than that of treating with cheap acids such as sulfuric acid plus reducing agents.

[0005] A patent document with publication number CN106848469A discloses a method for recovering valuable metals from waste lithium-ion batteries, which comprises mixing and grinding the waste lithium-ion batteries with chloride salts to obtain a mixture, roasting the mixture at a high temperature, and soaking the chlorinated solid product in water to obtain a salt solution containing valuable metals. This method has high energy consumption for recovering valuable metals, and produces chloride-containing gas during the reaction, which has a serious impact on the environment. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings and defects mentioned in the above background technology and provide a method for recovering valuable metal elements from waste lithium-ion batteries using a mechanical activation method.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is: A method for recovering valuable metal elements from waste lithium-ion batteries using a mechanical activation method comprises the following steps: (1) ball milling the waste lithium-ion battery positive electrode active material and the sulfur source to obtain an activated product; (2) The activated product is subjected to acid leaching to obtain a sulfur-containing filter residue and a solution containing valuable metals.

[0008] In the above-mentioned method of recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, preferably, the sulfur source is elemental sulfur, and the sulfur source accounts for 20%-30% of the total mass of the active material and the sulfur source.

[0009] In the above-mentioned method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, preferably, during the ball milling process, the mass ratio of the material to the grinding beads is 1:30-1:40, the ball milling speed is 500-870 rpm / min, and the ball milling time is 60-90 min.

[0010] In the above-mentioned method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, preferably, during the acid leaching process, one or more of sulfuric acid and hydrochloric acid with an acid concentration of 0.5 to 2.5 mol / L is selected, and the acid leaching time is 30 to 60 min.

[0011] In the above-mentioned method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, preferably, the sulfur-containing filter residue is placed in pure water for ultrasonic dispersion, and the supernatant is taken and subjected to solid-liquid separation to obtain elemental sulfur.

[0012] In the above method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, preferably, the ultrasonic dispersion time is 20-40 minutes.

[0013] In the above-mentioned method of recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, preferably, the positive electrode active material of the waste lithium-ion batteries is a powder obtained by discharging, disassembling, roasting and ball milling the positive electrode material of the lithium-ion batteries.

[0014] In the above-mentioned method of recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, preferably, the positive electrode material of the waste lithium-ion batteries is a positive electrode material containing at least one of nickel, cobalt and manganese.

[0015] The present invention mixes the active material of the waste lithium ion battery with the sulfur source, controls the activation degree of the positive electrode material by controlling the addition amount of the sulfur source and the rotation speed of the ball mill, and extrude the positive electrode material and the sulfur source by high-speed collision between balls during ball milling. When the positive electrode active material is ground, the heat generated by the collision and extrusion with the sulfur will also destroy the structure of the positive electrode material. The sulfur will also reduce the high-priced transition metal elements in the positive electrode material during the collision and extrusion process. No additional reducing agent needs to be added in the subsequent acid leaching process, and the sulfur does not participate in the acid leaching process during the acid leaching process. The sulfur can be recovered and reused, thereby realizing the efficient utilization of the valuable metals in the waste lithium ion batteries.

[0016] Compared with the prior art, the advantages of the present invention are: (1) The present invention can effectively reduce the transition metal elements in the positive electrode materials of waste lithium-ion batteries during ball milling through mechanical ball milling, thereby reducing the use of reducing agents. After activation, the reaction rate is significantly accelerated, the recovery rate of valuable metals is high, and the use of acidic solutions can be reduced.

[0017] (2) The present invention introduces elemental sulfur as a reducing agent in the process of recovering valuable metal elements from waste lithium-ion batteries using a mechanical activation method. The elemental sulfur that does not react during the mechanical activation can be recycled, and a small amount of sulfate generated by the elemental sulfur during the activation process can also reduce the loss of subsequent acid leaching.

[0018] (3) The processing process for recovering valuable metals from waste lithium-ion battery positive electrode materials of the present invention is simple to operate, can effectively avoid the generation of secondary pollution, has a short process time, low raw material cost, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a process flow chart for recovering valuable metal elements from waste lithium-ion batteries using a mechanical activation method.

[0020] Figure 2 It is the recovery rate of lithium and cobalt in the waste lithium cobalt oxide positive electrode material in Example 2 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

[0022] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0023] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0024] Embodiment 1: A method for recovering valuable metal elements in waste lithium-ion batteries using a mechanical activation method according to the present invention, the process flow chart of which is as follows Figure 1 As shown, the specific steps are as follows: (1) placing the waste lithium cobalt oxide positive electrode material into a 120 g / L sodium chloride solution for discharge treatment, disassembling the waste lithium ion battery after the discharge is completed to separate the positive electrode sheet, the separator, the negative electrode sheet, the electrolyte, and the shell; placing the positive electrode sheet into a muffle furnace for high-temperature roasting to completely separate the active material from the current collector aluminum foil, and ball-milling the separated active material to obtain lithium cobalt oxide positive electrode active powder; (2) placing lithium cobalt oxide positive electrode active material and elemental sulfur accounting for 20% of the total mass of active material and elemental sulfur into a ball mill, adding ball milling medium, with the mass ratio of material to grinding beads being 1:30, and ball milling for 60 minutes at a speed of 870 rpm for activation to obtain an active product; (3) adding the active product obtained in step (2) into a 2 mol / L sulfuric acid solution, leaching at 80° C. for 60 min, filtering, and obtaining a lithium-cobalt leaching solution and a sulfur-containing filter residue; detecting that the lithium recovery rate in the waste lithium cobalt oxide positive electrode material can reach 99%, and the cobalt recovery rate can reach 83%; (4) Add the sulfur-containing filter residue into pure water and ultrasonicate for 20 minutes. Let it settle for 1 hour. Filter the supernatant on the surface to obtain unreacted elemental sulfur, which can be reused.

[0025] Embodiment 2: A method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation is shown in the process flow chart. Figure 1 As shown, the specific steps are as follows: (1) placing the waste lithium cobalt oxide positive electrode material into a 120 g / L sodium chloride solution for discharge, disassembling the waste lithium ion battery after the discharge is completed to separate the positive electrode sheet, the separator, the negative electrode sheet, the electrolyte, and the shell, placing the positive electrode sheet in a muffle furnace for high-temperature roasting to completely separate the active material from the current collector aluminum foil, and ball-milling the separated waste lithium ion battery positive electrode active material to obtain lithium cobalt oxide active powder; (2) placing lithium cobalt oxide active powder and elemental sulfur accounting for 30% of the total mass of active materials and elemental sulfur into a ball mill, adding ball milling media, with a mass ratio of material to grinding beads of 1:40, and ball milling for 60 minutes at a speed of 870 rpm for activation to obtain an active product; (3) The active product obtained in step (2) was added to a 2 mol / L sulfuric acid solution, leached at 80°C for 60 min, and filtered to obtain a lithium-cobalt leaching solution and a sulfur-containing filter residue; the recovery rates of lithium and cobalt in the waste lithium cobalt oxide positive electrode material were detected. Figure 2 As shown, the lithium recovery rate can reach 99.59% and the cobalt recovery rate can reach 89.6%; (4) Add the sulfur-containing filter residue into pure water and ultrasonicate for 20 minutes. Let it settle for 1 hour. Filter the supernatant on the surface to obtain unreacted sulfur, which can be reused.

[0026] Comparative Example 1: The lithium cobalt oxide active powder prepared in step (1) of Example 2 was directly placed in a ball mill (the amount of lithium cobalt oxide active powder was the same as that in Example 2, and no elemental sulfur was added), and then a ball milling medium was added, with a mass ratio of material to grinding beads of 1:40, and the ball milling was carried out at a speed of 870 rpm for 60 min, and then added to a 2 mol / L sulfuric acid solution, leached at 80° C. for 60 min, and solid-liquid separation was performed to obtain a lithium cobalt leaching solution and a filter residue. The recovery rates of lithium and cobalt in the waste lithium cobalt oxide positive electrode material were detected. Figure 2 As shown, the lithium recovery rate can reach 86% and the cobalt recovery rate can reach 39.8%.

Claims

1. A method for recovering valuable metal elements from waste lithium-ion batteries using a mechanical activation method, characterized in that: The following steps are involved: (1) ball milling the waste lithium-ion battery positive electrode active material and the sulfur source to obtain an activated product; (2) The activated product is subjected to acid leaching to obtain a sulfur-containing filter residue and a solution containing valuable metals.

2. The method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation as claimed in claim 1, characterized in that: The sulfur source is elemental sulfur, and the sulfur source accounts for 20%-30% of the total mass of the active material and the sulfur source.

3. The method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation as claimed in claim 1, characterized in that: During the ball milling process, the mass ratio of the material to the grinding beads is 1:30-1:40, the ball milling speed is 500-870 rpm / min, and the ball milling time is 60-90 min.

4. The method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation as claimed in claim 1, characterized in that: During the acid leaching process, one or more of sulfuric acid and hydrochloric acid with an acid concentration of 0.5-2.5 mol / L are selected, the acid leaching time is 30-60 minutes, and the acid leaching is carried out at room temperature.

5. The method for recovering valuable metal elements from waste lithium-ion batteries using a mechanical activation method as described in any one of claims 1 to 4, characterized in that: The sulfur-containing filter residue is placed in pure water for ultrasonic dispersion, and the supernatant is taken and subjected to solid-liquid separation to obtain elemental sulfur.

6. The method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation as claimed in claim 5, characterized in that: The ultrasonic dispersion time is 20-40 min.

7. The method for recovering valuable metal elements from waste lithium-ion batteries using a mechanical activation method as described in any one of claims 1 to 4, characterized in that: The positive electrode active material of waste lithium ion batteries is a powder obtained by discharging, disassembling, roasting and ball milling the positive electrode material of lithium ion batteries.

8. The method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation as claimed in claim 7, characterized in that: The positive electrode material of the waste lithium-ion battery is a positive electrode material containing at least one of nickel, cobalt and manganese.

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