A method for efficient water immersion of waste ternary lithium battery powder

Abstract

This invention discloses a method for efficient water leaching of waste ternary lithium battery powder. It includes a pure water carbonation stage and a water leaching stage. Excess carbon dioxide and oxygen convert metal ions such as manganese, iron, and aluminum into hydroxide salt precipitates, which are then filtered out. The method of this application has a high water leaching rate and produces a single composition of the water-leached substances.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization, specifically to a method for efficient water leaching of waste ternary lithium battery powder. Background Technology

[0002] With the rapid development of the lithium battery industry, a large number of new energy batteries have been put into use in recent years. Ternary batteries, due to their high energy density, are widely used in automobiles, mobile phones, and energy storage facilities, while lithium batteries have an average lifespan of 6 years. Therefore, in the next few years, lithium batteries will enter a period of large-scale scrapping.

[0003] Currently, mainstream lithium battery recycling processes are divided into two types: wet and pyrometallurgical. The wet process mainly dissolves the metal components in ternary lithium batteries using acid and alkali solutions and then extracts them. However, this method generates a large amount of wastewater, easily causing secondary pollution. The pyrometallurgical process uses high-temperature calcination to cause oxidation-reduction reactions in the battery compounds, allowing for recycling. However, this method is still immature. For example, patent CN112374511A describes a method for preparing lithium carbonate and ternary precursors from recycled waste ternary lithium batteries. This method uses graphite and binders naturally present after battery pretreatment as reducing agents, and employs a carbonation-water leaching method to convert lithium carbonate into lithium bicarbonate, achieving preferential lithium leaching. However, this method suffers from low leaching rates in a single leaching cycle and complex composition of the leached substances, affecting equipment lifespan and the purity of the lithium carbonate product, thus making practical production difficult. In conclusion, there is an urgent need to develop an efficient, economical, and low-pollution method for preparing lithium carbonate from recycled waste ternary lithium batteries. Summary of the Invention

[0004] The problem to be solved by this invention is to address the shortcomings of the prior art by proposing a method for the efficient recycling and preparation of lithium carbonate from waste ternary lithium batteries. This method can be applied to the recycling and disposal of waste ternary lithium batteries and solves the problems of low leaching rate and complex composition of water-leached substances in traditional water leaching recycling technology.

[0005] To solve the above problems, the present invention adopts the following solution: a method for efficient water immersion of waste ternary lithium battery powder, characterized in that the method for efficient water immersion of waste ternary lithium battery powder includes a pure water carbonation stage and a water immersion stage.

[0006] In the pure water carbonation section, carbon dioxide is introduced into pure water for carbonation pretreatment to obtain a carbonated solution with a pH between 4 and 5.

[0007] The water immersion section includes: a multi-stage water immersion dissolution section, an oxidation precipitation section, a primary filtration and impurity removal section, a concentration section, and an evaporation section.

[0008] Multi-stage water leaching stage: The carbonation solution is mixed with the battery powder, and excess carbon dioxide is introduced and stirred to ensure that the carbonation solution and battery powder are fully mixed, so that the metal ions in the battery powder are converted into bicarbonate and dissolved in water. After water leaching, the water and powder are separated into solid and liquid. The residue after separation can be repeated for multi-stage water leaching treatment, and the separated water leaching solution is collected.

[0009] Oxidation precipitation section: Oxygen is introduced into the water-leached solution to precipitate manganese and iron in the solution. Simultaneously, aluminum in the solution undergoes hydrolysis, forming aluminum hydroxide which then settles. The reaction equations are as follows:

[0010] 4Mn(HCO3)2+O2+2H2O→4Mn(OH)3↓+8CO2;

[0011] 4Fe(HCO3)2+O2+2H2O→4Fe(OH)3↓+8CO2;

[0012] Al(HCO3)3+3H2O→Al(OH)3↓+3CO2+3H2O.

[0013] First filtration to remove impurities: After the reaction is complete, perform a first filtration to remove precipitated manganese hydroxide, iron hydroxide, and aluminum hydroxide, and obtain a first filtrate.

[0014] Concentration section: The filtrate after the first filtration to remove impurities is sent to the reverse osmosis membrane for concentration to obtain concentrated water and purified water.

[0015] Evaporation section: The concentrated water is sent to the evaporation equipment for evaporation to obtain lithium carbonate powder.

[0016] Furthermore, the method for efficient water immersion of waste ternary lithium battery powder is characterized in that the water immersion section further includes a water dissolution section and a secondary filtration and impurity removal section.

[0017] Furthermore, the method for efficient water leaching of waste ternary lithium battery powder is characterized in that the multi-stage water leaching dissolution stage has a water leaching time of 30 to 60 minutes for each stage, the solution pH should be between 5 and 8, and the powder-to-water ratio should be between 1:8 and 1:40.

[0018] Furthermore, the method for efficient water immersion of waste ternary lithium battery powder is characterized in that the battery powder needs to be pretreated before being mixed with the carbonation solution for water immersion. The pretreatment of the battery powder includes electromagnetic discharge, crushing, sieving and oxygen-free roasting.

[0019] Furthermore, the method for efficient water leaching of waste ternary lithium battery powder is characterized in that the medium through which oxygen is introduced in the oxidation precipitation section is pure oxygen or air, and the aeration rate needs to meet 6-8 (molO2) / (m³). 3(solution), the aeration time shall not be less than 30 min; the reaction temperature of the oxidation precipitation section shall be 5-25℃.

[0020] Furthermore, the method for efficient water leaching of waste ternary lithium battery powder is characterized in that the multi-stage water leaching dissolution stage and the oxidation precipitation stage can be carried out simultaneously, that is, oxygen is introduced at the same time as carbon dioxide.

[0021] Furthermore, the method for efficient water leaching of waste ternary lithium battery powder is characterized in that the lithium carbonate powder obtained by evaporation is dissolved in the purified water obtained in the concentration section at a temperature of 5-20°C, and after complete dissolution, a pure lithium carbonate solution is obtained by secondary filtration using an ultrafiltration device to remove impurities.

[0022] The oxidation precipitation stage can be carried out simultaneously with the water leaching stage to improve the dissolution efficiency of battery powder in the solution. Alternatively, it can be carried out separately to remove Mn from the solution. + Al 3+ The purpose is to remove impurities.

[0023] After being crushed and calcined in an oxygen-free environment, the main components of a ternary lithium battery are lithium carbonate and a small amount of lithium fluoride. In the multi-stage water leaching stage, excess carbon dioxide is introduced, converting lithium carbonate into lithium bicarbonate, which dissolves in water. In the oxidation precipitation stage, oxygen is introduced, causing lithium bicarbonate to form lithium hydroxide, which dissolves in water. The reaction temperature in the oxidation precipitation stage should be 5–25°C. At low temperatures, the solubility of manganese hydroxide and aluminum hydroxide further decreases, while the solubility of lithium bicarbonate increases with decreasing temperature. Therefore, at low temperatures, the levels of Mn and Al ions in water will further decrease. The solubility product constant of lithium carbonate can be simplified as follows:

[0024] K s =c(Li + )×c(HCO3 - )

[0025] Therefore, during the dissolution process, the continuous introduction of carbon dioxide and oxygen can cause bicarbonates such as Mn(HCO3)2, Fe(HCO3)2, and Al(HCO3)3 in the solution to react and precipitate, thereby reducing the concentration of bicarbonate ions in the solution, further promoting the reaction and dissolution of lithium bicarbonate in the battery powder, and improving the solution dissolution efficiency.

[0026] The solution used in the water dissolution stage is the purified water produced in the concentration stage. The purpose of water dissolution is to remove insoluble impurities from the oxidized and evaporated lithium carbonate powder in a secondary purification process. The dissolution temperature is controlled between 5 and 20°C. Lithium carbonate has a solubility of 13g / 100g in water at 25°C; by controlling the temperature, the lithium carbonate in the battery powder can be dissolved in water. Insoluble impurities are filtered through a filter press. Attached Figure Description

[0027] Figure 1Flowchart of efficient water immersion process for waste ternary lithium battery powder. Detailed Implementation

[0028] Example 1:

[0029] The battery powder obtained from the recycled ternary lithium batteries after discharge, crushing, screening, and calcination pretreatment was mixed with a solution pre-carbonated with pure water at a powder-to-water ratio of 1:28 at 20°C. Simultaneously, two Roots blowers were used to introduce air and carbon dioxide into the solution through aeration discs, with an aeration rate of 2 m³ / s. 3 air / m 3 The solution was aerated for 1 hour. Continuous oxygen flow suppressed the dissolution of Mn and Al ions, while bicarbonate ions reacted with Li, increasing Li solubility. The resulting solution was filtered using a plate and frame filter press and then concentrated via reverse osmosis. The concentrated solution was then evaporated at 80°C using an MVR evaporator to obtain lithium carbonate powder. The lithium carbonate powder was then dissolved a second time with reverse osmosis purified water at 10°C for 1 hour. The resulting solution was filtered through an ultrafiltration system to obtain a pure lithium carbonate solution.

[0030] Example 2:

[0031] The battery powder obtained from the recycled ternary lithium batteries after discharge, crushing, screening, and calcination pretreatment was mixed with a solution pre-carbonated with pure water at a powder-to-water ratio of 1:28 at 20°C. Simultaneously, a Roots blower introduced carbon dioxide into the solution through an aeration disc at a flow rate of 2 m³ / s. 3 air / m 3 The solution was aerated for 1 hour. Due to the continuous introduction of carbon dioxide into the water, metallic substances such as Li, Mn, and Al in the solution continuously dissolved into bicarbonates. After the reaction, the solution was filtered using a plate and frame filter press. The residue after filtration under the same leaching conditions under multiple stages of water leaching was then subjected to the same process. The filtered solution was then fed into an aeration tank for aeration treatment using pure oxygen at an aeration rate of 0.15 m³ / h. 3 O2 / m 3 The solution was reacted for 1 hour to form hydroxide ions as precipitates. The solution was then filtered through an ultrafiltration system to remove the precipitates. The ultrafiltration solution was then concentrated using a reverse osmosis system. The concentrated solution was then evaporated at 80°C using an MVR evaporator to obtain lithium carbonate powder. The lithium carbonate powder was then dissolved a second time with reverse osmosis purified water at 10°C for 1 hour. The resulting solution was then filtered through an ultrafiltration system to obtain a pure lithium carbonate solution.

Claims

1. A method for efficient water immersion of waste ternary lithium battery powder, characterized in that, The method for efficient water immersion of waste ternary lithium battery powder includes a pure water carbonation stage and a water immersion stage. In the pure water carbonation section, carbon dioxide is introduced into pure water for carbonation pretreatment to obtain a carbonated solution with a pH between 4 and 5. The water leaching section includes: a multi-stage water leaching dissolution section, an oxidation precipitation section, a primary filtration and impurity removal section, a concentration section, and an evaporation section; Multi-stage water leaching stage: Carbonated solution is mixed with battery powder, and excess carbon dioxide is introduced while stirring to ensure thorough mixing. This allows metal ions in the battery powder to dissolve in water as bicarbonates. After leaching, the water and powder undergo solid-liquid separation. The residue can be repeated through the multi-stage water leaching process, and the separated water leaching solution is collected. Oxidation precipitation stage: Oxygen is introduced into the water leaching solution to precipitate manganese and iron. Simultaneously, aluminum in the solution undergoes hydrolysis to form aluminum hydroxide, which then settles. The reaction equation is as follows: 4Mn(HCO3)2+O2+2H2O→4Mn(OH)3↓+8CO2; 4Fe(HCO3)2+O2+2H2O→4Fe(OH)3↓+8CO2; Al(HCO3)3+3H2O→Al(OH)3↓+3CO2+3H2O; First filtration to remove impurities: After the reaction is complete, perform a first filtration to remove the precipitated manganese hydroxide, iron hydroxide, and aluminum hydroxide, and obtain the first filtrate; Concentration section: The filtrate after the first filtration to remove impurities is sent to the reverse osmosis membrane for concentration to obtain concentrated water and purified water; Evaporation section: The concentrated water is sent to the evaporation equipment for evaporation to obtain lithium carbonate powder.

2. The method for efficient water immersion of waste ternary lithium battery powder according to claim 1, characterized in that, The water immersion section also includes a water dissolution section and a secondary filtration and impurity removal section.

3. The method for efficient water immersion of waste ternary lithium battery powder according to claim 1, characterized in that, The multi-stage water leaching stage has a leaching time of 30-60 minutes for each stage, the solution pH should be between 5 and 8, and the powder-to-water ratio should be between 1:8 and 1:

40.

4. The method for efficient water immersion of waste ternary lithium battery powder according to claim 1, characterized in that, The battery powder needs to be pretreated before being mixed with the carbonation solution and immersed in water. The pretreatment of the battery powder includes electromagnetic discharge, crushing, sieving and oxygen-free roasting.

5. The method for efficient water immersion of waste ternary lithium battery powder according to claim 1, characterized in that, The medium through which oxygen is introduced in the oxidation precipitation section is pure oxygen or air, and the aeration rate needs to meet 6-8 (molO2) / (m³). 3 (solution), the aeration time shall not be less than 30 min; the reaction temperature of the oxidation precipitation section shall be 5-25℃.

6. The method for efficient water immersion of waste ternary lithium battery powder according to claim 1, characterized in that, The multi-stage water leaching and oxidation precipitation stages can be carried out simultaneously, that is, oxygen is introduced at the same time as carbon dioxide.

7. The method for efficient water immersion of waste ternary lithium battery powder according to claim 2, characterized in that, The lithium carbonate powder obtained by evaporation is dissolved in the purified water obtained in the concentration section at 5-20℃. After complete dissolution, a pure lithium carbonate solution is obtained by secondary filtration using an ultrafiltration device to remove impurities.

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