A method for extracting lithium from waste ternary lithium-ion battery cathode materials and preparing Li4SiO4 adsorbent.

Abstract

This invention relates to a method for extracting lithium from waste ternary lithium-ion battery cathode materials and preparing Li4SiO4 adsorbent, belonging to the field of resource recycling technology. Under oxygen-free conditions, the waste ternary battery cathode materials are uniformly heated to 400-600℃, and then reduced with hydrogen gas for 60-120 minutes under constant temperature conditions to obtain reduced waste. Based on the Li content in the reduced waste, silicon cutting waste is added to the reduced waste and ground and mixed to obtain a mixture. The molar ratio of Li to Si in the mixture is 4.0-4.4:1. Under a protective atmosphere, the mixture is uniformly heated to 1300-1500℃ and reduced and smelted at a constant temperature for 60-90 minutes. The mixture is then cooled to room temperature in the furnace, and the alloy phase and slag are separated. The slag is then ground to obtain the Li4SiO4 adsorbent. This invention employs a two-step thermal reduction process using hydrogen and waste silicon to simultaneously prepare Li4SiO4 material and separate Ni, Co, and Mn alloys, thereby reducing the preparation cost of Li4SiO4, minimizing environmental pollution, and improving the comprehensive utilization of non-ferrous metal resources.

Description

Technical Field

[0001] This invention relates to a method for extracting lithium from waste ternary lithium-ion battery cathode materials and preparing Li4SiO4 adsorbent, belonging to the field of resource recycling technology. Background Technology

[0002] The extensive use of fossil fuels in industrial production has led to a sharp increase in atmospheric CO2 levels, making efficient CO2 capture and storage a research hotspot. Li4SiO4 materials are considered the most promising high-temperature solid adsorbents for CO2 due to their excellent high-temperature CO2 adsorption performance. However, preparing Li4SiO4 materials using pure reagents as raw materials is costly and results in poor adsorption performance. Currently, many researchers use natural silicon sources and silicon-containing waste as raw materials to prepare Li4SiO4 materials. These raw materials are abundant and readily available, and using solid waste as raw materials has a positive effect on environmental protection to some extent. These silicon-containing substances can reduce preparation costs, and the impurity elements can act as dopant elements, affecting the normal growth of lithium silicate particles, increasing their specific surface area, and further improving the adsorption performance of Li4SiO4 materials. However, excessive impurities can lead to low Si content, affecting the purity of the Li4SiO4 material and resulting in poor adsorption performance of lithium silicate. Therefore, selecting suitable raw materials is crucial for the preparation of lithium silicate adsorbents. However, using silicon-containing materials as raw materials has a limited impact on the production cost of lithium silicate. Lithium resources are expensive, and the Li in the cathode materials of spent batteries... + As a lithium source, it greatly reduces the production cost of lithium silicate. Summary of the Invention

[0003] To address the problems of high production costs and complex pretreatment processes for inexpensive raw materials in existing lithium silicate production methods, this invention proposes a method for extracting lithium from waste ternary lithium-ion battery cathode materials and preparing Li4SiO4 adsorbent. Specifically, using hydrogen and silicon waste as reducing agents, a two-step thermal reduction process is performed at low and high temperatures respectively. This process recovers Ni, Co, and Mn from the waste ternary lithium battery cathode material in an alloy form, while Li is enriched in the slag to form Li4SiO4. This simultaneously achieves the separation of Li4SiO4 material preparation from the Ni, Co, and Mn alloy, reducing the production cost of Li4SiO4, minimizing environmental pollution, and improving the comprehensive utilization of non-ferrous metal resources.

[0004] A method for extracting lithium from waste ternary lithium-ion battery cathode materials and preparing Li4SiO4 adsorbent, the specific steps of which are as follows:

[0005] (1) Under oxygen-free conditions, the ternary battery cathode waste is heated at a constant rate to a temperature of 400-600℃, and hydrogen is introduced for reduction for 60-120 minutes under constant temperature conditions to obtain reduced waste.

[0006] (2) Based on the Li content in the reduction waste, silicon cutting waste is added to the reduction waste and ground and mixed to obtain a mixture. The molar ratio of Li to Si in the mixture is 4.0 to 4.4:1.

[0007] (3) Under a protective atmosphere, the mixture is heated at a constant rate to 1300-1500℃ and then reduced and smelted at a constant temperature for 60-90 minutes. The mixture is then cooled to room temperature in the furnace, and the alloy phase and smelting slag are separated. The smelting slag is then ground to obtain the Li4SiO4 adsorbent.

[0008] The uniform heating rate in step (1) is 5-10℃ / min.

[0009] In step (1), the hydrogen gas introduction rate is 1500-250 mL / min.

[0010] The protective atmosphere in step (3) is nitrogen or argon, and the uniform heating rate is 5-10℃ / min.

[0011] The beneficial effects of this invention are:

[0012] (1) This invention uses hydrogen-silicon synergistic treatment of ternary lithium battery waste to prepare Li4SiO4 material, and uses two kinds of solid waste, lithium battery cathode waste and silicon cutting waste, to prepare carbon dioxide adsorbent-doped Li4SiO4, while recovering valuable metals Ni, Co and Mn in lithium-ion battery cathode.

[0013] (2) Hydrogen is used to convert Ni, Co and Mn oxides in ternary lithium battery waste into metallic elements, which reduces the amount of silicon waste used in the thermal reduction process. Only the molar ratio of Li to Si in the mixture needs to be 4-4.4:1 to meet the preparation conditions of Li4SiO4. This process does not require the addition of Li2CO3 reagent. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of the present invention;

[0015] Figure 2 The adsorption curve of CO2 by lithium silicate adsorbent in Example 1 is shown. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0017] Example 1: A method for extracting lithium from waste ternary lithium-ion battery cathode material and preparing Li4SiO4 adsorbent (see Example 2). Figure 1 The specific steps are as follows:

[0018] (1) The ternary battery positive electrode waste was loaded into an alumina crucible and placed in a resistance furnace. Under an argon atmosphere, the ternary battery positive electrode waste was heated to 500℃ at a constant heating rate of 10℃ / min. Under a constant temperature of 500℃, hydrogen was introduced at a rate of 200mL / min for 90min to reduce the waste and obtain the reduced waste. The reduced waste contained LiOH, Ni, Co and MnO.

[0019] (2) Based on the Li content in the reduction waste, silicon cutting waste is added to the reduction waste and ground and mixed to obtain a mixture. The molar ratio of Li to Si in the mixture is 4.4:1.

[0020] (3) Under an argon atmosphere, the mixture is heated at a rate of 10℃ / min to 1300℃, 1400℃ and 1500℃ respectively and then reduced and smelted at a constant temperature for 60 min. The mixture is then cooled to room temperature in the furnace, and the alloy phase and smelting slag are separated. The smelting slag is then ground to obtain Li4SiO4 adsorbent.

[0021] Tests showed that, by mass percentage, at 1300℃, the Li4SiO4 adsorbent contained 99.4% Li4SiO4, 0.5% Li2SiO3, and 0.1% MnO; at 1400℃, it contained 98.2% Li4SiO4, 1.7% Li2SiO3, and 0.1% MnO; and at 1500℃, it contained 95.7% Li4SiO4, 4.1% Li2SiO3, and 0.2% MnO.

[0022] The Li4SiO4 adsorbent was subjected to CO2 adsorption tests. Isothermal adsorption thermogravimetric analysis was performed at 700℃ under a 100% CO2 atmosphere, and the isothermal carbon dioxide adsorption lasted for 120 min (see...). Figure 2 In this embodiment, the saturated adsorption capacity of the 1300℃-Li4SiO4 adsorbent is 0.38 g / g, which is better than the other two groups. From the perspective of adsorbent composition, the main substance of the adsorbent is Li4SiO4, accounting for 99.4%. Under high temperature conditions, Li4SiO4 will partially decompose. At the same time, the preparation temperature also affects the adsorption capacity of Li4SiO4. The increase of temperature will reduce the specific surface area of ​​lithium silicate particles, thereby reducing the CO2 contact area during adsorption and reducing its adsorption capacity.

[0023] Example 2: A method for extracting lithium from waste ternary lithium-ion battery cathode material and preparing Li4SiO4 adsorbent (see Example 2). Figure 1 The specific steps are as follows:

[0024] (1) The ternary battery positive electrode waste was loaded into an alumina crucible and placed in a resistance furnace. Under an argon atmosphere, the ternary battery positive electrode waste was heated to 400℃ at a constant heating rate of 8℃ / min. Under a constant temperature of 400℃, hydrogen was introduced at a rate of 250mL / min for 120min to reduce the waste to obtain reduced waste. The reduced waste contained LiOH, Ni, Co and MnO.

[0025] (2) Based on the Li content in the reduction waste, silicon cutting waste is added to the reduction waste and ground and mixed to obtain a mixture. The molar ratio of Li to Si in the mixture is 4.2:1.

[0026] (3) Under an argon atmosphere, the mixture is heated to 1350°C at a heating rate of 8°C / min and then reduced and smelted at a constant temperature for 90 min. It is then cooled to room temperature in the furnace, and the alloy phase and smelting slag are separated. The smelting slag is then ground to obtain Li4SiO4 adsorbent.

[0027] According to the test, the Li4SiO4 adsorbent contains 99.0% Li4SiO4, 0.9% Li2SiO3, and 0.1% MnO by mass percentage.

[0028] The Li4SiO4 adsorbent was subjected to CO2 adsorption tests. Under a 100% CO2 atmosphere, isothermal adsorption thermogravimetric analysis was performed at 700°C for 120 min. The saturated adsorption capacity of the Li4SiO4 adsorbent in this example was 0.39 g / g. Due to its preparation at a relatively low temperature and high Li4SiO4 content, it exhibited relatively good adsorption capacity in the five sets of tests.

[0029] Example 3: A method for extracting lithium from waste ternary lithium-ion battery cathode material and preparing Li4SiO4 adsorbent (see Example 3). Figure 1 The specific steps are as follows:

[0030] (1) The ternary battery positive electrode waste was loaded into an alumina crucible and placed in a resistance furnace. Under an argon atmosphere, the ternary battery positive electrode waste was heated to 600℃ at a constant heating rate of 5℃ / min. Under a constant temperature of 600℃, hydrogen was introduced at a rate of 150mL / min for 90min to reduce the waste and obtain the reduced waste. The reduced waste contained LiOH, Ni, Co and MnO.

[0031] (2) Based on the Li content in the reduction waste, silicon cutting waste is added to the reduction waste and ground and mixed to obtain a mixture. The molar ratio of Li to Si in the mixture is 4:1.

[0032] (3) Under an argon atmosphere, the mixture is heated to 1450°C at a heating rate of 5°C / min and then reduced and smelted at a constant temperature for 80 min. The mixture is then cooled to room temperature in the furnace, and the alloy phase and smelting slag are separated. The smelting slag is then ground to obtain the Li4SiO4 adsorbent.

[0033] According to the test results, the Li4SiO4 adsorbent contains 97.5% Li4SiO4, 2.3% Li2SiO3, and 0.2% MnO by mass percentage.

[0034] The Li4SiO4 adsorbent was subjected to CO2 adsorption tests. The isothermal adsorption thermogravimetric analysis was performed at 700°C under a 100% CO2 atmosphere. The isothermal carbon dioxide adsorption lasted for 120 minutes. In this example, the Li4SiO4 adsorbent was prepared at a relatively high temperature of 1450°C, which resulted in an increased loss of Li4SiO4. The reaction Li4SiO4→Li2SiO3+Li2O affected its adsorption capacity.

[0035] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for extracting lithium from waste ternary lithium-ion battery cathode material and preparing Li4SiO4 adsorbent, characterized in that, The specific steps are as follows: (1) Under oxygen-free conditions, the ternary battery cathode waste is heated at a constant rate to a temperature of 400-600℃, and hydrogen is introduced for reduction for 60-120 minutes under constant temperature conditions to obtain reduced waste. (2) Based on the Li content in the reduction waste, silicon cutting waste is added to the reduction waste and ground and mixed to obtain a mixture. The molar ratio of Li to Si in the mixture is 4.0 to 4.4:

1. (3) Under a protective atmosphere, the mixture is heated at a constant rate to 1300-1500℃ and then reduced and smelted at a constant temperature for 60-90 minutes. The mixture is then cooled to room temperature in the furnace, and the alloy phase and smelting slag are separated. The smelting slag is then ground to obtain the Li4SiO4 adsorbent.

2. The method for extracting lithium from waste ternary lithium-ion battery cathode material and preparing Li4SiO4 adsorbent according to claim 1, characterized in that: Step (1) The heating rate is 5-10℃ / min.

3. The method for extracting lithium from waste ternary lithium-ion battery cathode material and preparing Li4SiO4 adsorbent according to claim 1, characterized in that: Step (1) The hydrogen gas introduction rate is 150-250 mL / min.

4. The method for extracting lithium from waste ternary lithium-ion battery cathode material and preparing Li4SiO4 adsorbent according to claim 1, characterized in that: Step (3) The protective atmosphere is nitrogen or argon, and the uniform heating rate is 5-10℃ / min.

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