Deep impurity removal and lithium extraction process for ternary lithium battery waste

Abstract

The invention relates to the technical field of battery waste treatment, in particular to a ternary lithium battery waste deep impurity removal and lithium extraction process which comprises the following steps: step 1, carrying out mechanical disassembly and physical separation on ternary lithium battery waste to separate out positive plates, and crushing and screening to obtain lithium-rich positive powder; 2, carrying out sulfuric acid leaching treatment on the positive electrode powder, adding a reducing agent hydrogen peroxide, and controlling the reaction temperature, time and liquid-solid ratio to realize leaching of lithium; 3, performing multi-stage purification treatment on the pickle liquor, and sequentially removing impurities such as iron, aluminum, copper, calcium and magnesium; 4, enriching and purifying lithium in the purified liquid by adopting a solvent extraction or electrodialysis method; 5, sodium carbonate is added into the lithium-rich solution for a precipitation reaction, lithium carbonate is generated, and a product is obtained after washing and drying. According to the process, microwave-assisted acid leaching is adopted, the reaction time is shortened, the energy consumption is greatly reduced, and a carbonate deep impurity removal step is innovatively introduced.

Description

Technical Field

[0001] This invention relates to the field of battery waste treatment, and in particular to a deep purification and lithium extraction process for ternary lithium battery waste. Background Technology

[0002] With the explosive growth of the new energy vehicle market, the consumption and waste of ternary lithium batteries have been increasing year by year. The cathode material of ternary lithium batteries contains a variety of high-value metals such as lithium, nickel, cobalt, and manganese. Efficient recycling of these materials is a key way to alleviate resource shortages, reduce environmental pollution, and achieve sustainable development.

[0003] Currently, the mainstream method for recycling valuable metals from ternary batteries is hydrometallurgical processes, which typically include pretreatment, acid leaching, impurity removal, enrichment, and precipitation. However, traditional acid leaching processes are time-consuming and energy-intensive, and the leaching efficiency of lithium is easily limited in the presence of high concentrations of cobalt and nickel. Lithium carbonate prepared by conventional precipitation methods is mostly industrial grade with poor physical properties (such as morphology and tap density), making it unsuitable for direct use in the preparation of high-performance lithium battery cathode materials, resulting in low added value.

[0004] Therefore, developing a complete recycling process that is highly efficient in leaching, thoroughly removes impurities, can directly produce high-end lithium products, and is environmentally friendly has become an urgent need for the industry. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a deep purification and lithium extraction process for ternary lithium battery waste.

[0006] This invention provides a deep purification and lithium extraction process for ternary lithium battery waste, comprising the following steps:

[0007] Step 1: Mechanically dismantle and physically sort the waste ternary lithium batteries to separate the positive electrode sheets, which are then crushed and sieved to obtain lithium-rich positive electrode powder.

[0008] Step 2: The positive electrode powder is subjected to sulfuric acid leaching treatment, and hydrogen peroxide, a reducing agent, is added. The reaction temperature, time and liquid-solid ratio are controlled to achieve efficient lithium leaching.

[0009] Step 3: The acid leaching solution undergoes multi-stage purification treatment to remove impurities such as iron, aluminum, copper, calcium, and magnesium in sequence;

[0010] Step 4: Enrich and purify lithium in the purified liquid using solvent extraction or electrodialysis.

[0011] Step 5: Add sodium carbonate to the lithium-rich solution to carry out a precipitation reaction to generate lithium carbonate. After washing and drying, battery-grade lithium carbonate product is obtained.

[0012] Preferably, in step two: the sulfuric acid concentration is 2.0–3.0 mol / L, the hydrogen peroxide volume fraction is 2–5%, the reaction temperature is 90–110℃, the time is 2–4 h, the liquid-solid ratio is 4:1–6:1, and the acid excess coefficient is 1.1–1.3.

[0013] Preferably, step three specifically includes:

[0014] First, add calcium hydroxide to adjust the pH to 4.5–5.5 to precipitate iron and aluminum;

[0015] Add sodium hydroxide to adjust the pH to 10–11 to further remove residual impurities.

[0016] Preferably, in step four, the extractant is a tributyl phosphate (TBP) kerosene system, the extraction ratio O / A is 1:1–3:1, and the back-extraction agent is dilute sulfuric acid.

[0017] Preferably, step four includes: when using electrodialysis, using a selective ion exchange membrane, with an operating voltage of 10–30V and a current density of 50–200A / m².

[0018] Preferably, step five specifically includes: controlling the reaction temperature to 80–90℃, the stirring speed to 200–400 rpm, the sedimentation time to 1–2 h, and adding sodium carbonate as the precipitant at 1.05–1.10 times the theoretical amount.

[0019] Preferably, step two further includes alkaline absorption treatment of the acidic waste gas generated during the acid leaching process, wherein the absorption liquid is a sodium hydroxide solution, and sodium sulfate solution is generated after absorption.

[0020] Preferably, step three further includes: using microwave-assisted enhanced leaching, with a microwave power of 500-1000W and a frequency of 2450MHz, and auxiliary heating to 90-110℃, shortening the reaction time to 0.5-1.5 hours.

[0021] Preferably, between step three and step four, the following further step is taken: adding a sodium carbonate solution with a concentration of 0.1-0.5 mol / L to the purification solution, controlling the pH to 10.5-11.5, the reaction temperature to 50-70℃, stirring the reaction for 0.5-1 hour, and deeply precipitating and removing calcium, magnesium, and strontium alkaline earth metal ions from the solution.

[0022] Preferably, step five is performed under the action of an ultrasonic field, with an ultrasonic frequency of 20-40 kHz, a power density of 50-200 W / L, and a reaction time of 20-40 minutes.

[0023] After aging and spray drying, primary lithium carbonate crystals are used to obtain battery-grade lithium carbonate products with high sphericity and tap density greater than 2.2 g / cm³.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Significantly improved efficiency: Microwave-assisted acid leaching shortens reaction time and greatly reduces energy consumption.

[0026] 2. Deep impurity removal for extremely high purity: An innovative deep impurity removal step for carbonate ions is introduced, which effectively removes difficult-to-treat alkaline earth metal impurities, ensuring the preparation of ultra-high purity lithium products.

[0027] 3. Excellent product performance and high value: By combining ultrasonic-assisted precipitation with spray drying post-treatment, battery-grade lithium carbonate products with high sphericity and high tap density are directly obtained, which meets the requirements of high-end lithium battery manufacturing and greatly enhances product value and market competitiveness.

[0028] 4. Green and environmentally friendly: The entire process incorporates the concepts of resource utilization and harmlessness, achieving the coordinated treatment and recycling of waste gas, wastewater, and waste residue, resulting in significant environmental benefits. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0030] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0031] A deep purification and lithium extraction process for ternary lithium battery waste includes the following steps:

[0032] Step 1: Mechanically dismantle and physically sort the waste ternary lithium batteries to separate the positive electrode sheets, which are then crushed and sieved to obtain lithium-rich positive electrode powder.

[0033] Step 2: The positive electrode powder is subjected to sulfuric acid leaching treatment, and hydrogen peroxide, a reducing agent, is added. The reaction temperature, time and liquid-solid ratio are controlled to achieve efficient lithium leaching.

[0034] Step 3: The acid leaching solution undergoes multi-stage purification treatment to remove impurities such as iron, aluminum, copper, calcium, and magnesium in sequence;

[0035] Step 4: Enrich and purify lithium in the purified liquid using solvent extraction or electrodialysis.

[0036] Step 5: Add sodium carbonate to the lithium-rich solution to carry out a precipitation reaction to generate lithium carbonate. After washing and drying, battery-grade lithium carbonate product is obtained.

[0037] As an optional embodiment, in step two: the sulfuric acid concentration is 2.0–3.0 mol / L, the hydrogen peroxide volume fraction is 2–5%, the reaction temperature is 90–110℃, the time is 2–4 h, the liquid-solid ratio is 4:1–6:1, and the acid excess coefficient is 1.1–1.3.

[0038] As an optional embodiment, step three specifically includes:

[0039] First, add calcium hydroxide to adjust the pH to 4.5–5.5 to precipitate iron and aluminum;

[0040] Add sodium hydroxide to adjust the pH to 10–11 to further remove residual impurities.

[0041] As an optional embodiment, in step four, the extractant is a tributyl phosphate (TBP) kerosene system, the extraction ratio O / A is 1:1–3:1, and the back-extraction agent is dilute sulfuric acid.

[0042] As an optional embodiment, step four includes: when using electrodialysis, using a selective ion exchange membrane, with an operating voltage of 10–30V and a current density of 50–200A / m².

[0043] As an optional embodiment, step five specifically includes: controlling the reaction temperature to 80–90℃, the stirring speed to 200–400 rpm, the sedimentation time to 1–2 h, and adding sodium carbonate as the precipitant at 1.05–1.10 times the theoretical amount.

[0044] As an optional embodiment, step two further includes alkaline absorption treatment of the acidic waste gas generated during the acid leaching process. The absorption liquid is a sodium hydroxide solution, which generates a sodium sulfate solution after absorption.

[0045] As an optional embodiment, step three further includes: using microwave-assisted enhanced leaching, with a microwave power of 500-1000W and a frequency of 2450MHz, and auxiliary heating to 90-110℃, shortening the reaction time to 0.5-1.5 hours.

[0046] As an optional embodiment, between step three and step four, the following further step is taken: adding a sodium carbonate solution with a concentration of 0.1-0.5 mol / L to the purification solution, controlling the pH to 10.5-11.5, the reaction temperature to 50-70℃, stirring the reaction for 0.5-1 hour, and deeply precipitating and removing calcium, magnesium, and strontium alkaline earth metal ions from the solution.

[0047] As an optional embodiment, step five is performed under the action of an ultrasonic field, with an ultrasonic frequency of 20-40kHz, a power density of 50-200 W / L, and a reaction time of 20-40 minutes.

[0048] After aging and spray drying, primary lithium carbonate crystals are used to obtain battery-grade lithium carbonate products with high sphericity and tap density greater than 2.2 g / cm³.

[0049] Example 1: Microwave-assisted acid leaching-extraction enrichment route

[0050] Take 1 kg of ternary cathode powder (Li content 3.6%) obtained after pretreatment.

[0051] 1. Acid leaching: The positive electrode powder was placed in a microwave reactor, and 5L of 2.5mol / L sulfuric acid and 3% hydrogen peroxide were added. The microwave was turned on, the power was set to 800W, the temperature was raised to 100℃ and maintained for 1 hour. After the reaction, the mixture was filtered, and the lithium leaching rate was measured to be 98.5%.

[0052] 2. Multi-stage purification: First, add Ca(OH)2 to the leachate to adjust the pH to 5.0, precipitate and filter to remove Fe and Al, then add NaOH to adjust the pH to 10.5, precipitate and filter to remove Cu and other impurities. Subsequently, perform deep purification by adding 0.3 mol / L Na2CO3 solution to the filtrate, controlling the pH to 11.0, stirring and reacting at 60℃ for 0.5 hours, and filtering to remove Ca²⁺ and Mg²⁺.

[0053] 3. Enrichment and purification: Solvent extraction was used with 25% TBP-kerosene as the organic phase. The purified liquid was subjected to three-stage countercurrent extraction at an O / A ratio of 2:1. The liquid was then back-extracted with 0.5 mol / L H2SO4 to obtain a high-purity lithium-rich solution.

[0054] 4. Lithium precipitation: Heat the lithium-rich solution to 85°C, and add 1.08 times the amount of saturated Na2CO3 solution while stirring at 300 rpm. React for 1 hour, filter, wash with hot water, and then send the wet lithium carbonate into a spray drying tower with an inlet temperature of 200°C and an outlet temperature of 90°C to obtain the dried product.

[0055] 5. Treatment of three wastes: absorption of waste gas and alkaline solution, reuse of wastewater, and outsourcing of waste residue treatment;

[0056] Test results: The final product is spherical lithium carbonate with a chemical purity of 99.7%, a tap density of 2.25 g / cm³, and a total lithium recovery rate of 91.2%.

[0057] Example 2: Conventional acid leaching-electrodialysis enrichment route

[0058] Take 1 kg of the same positive electrode powder as in Example 1;

[0059] 1. Acid leaching: Conventional electric heating was used, under the same conditions as in Example 1 (100°C, 3 hours), with a lithium leaching rate of 98.0%;

[0060] 2. Multi-stage purification: First, add Ca(OH)2 to the leachate to adjust the pH to 5.0, precipitate and filter to remove Fe and Al, then add NaOH to adjust the pH to 10.5, precipitate and filter to remove Cu and other impurities. Subsequently, perform deep purification by adding 0.3 mol / L Na2CO3 solution to the filtrate, controlling the pH to 11.0, stirring and reacting at 60℃ for 0.5 hours, and filtering to remove Ca²⁺ and Mg²⁺.

[0061] 3. Enrichment and purification: Electrodialysis is used with a selective ion exchange membrane to enrich the purified liquid under the conditions of operating voltage 20V and current density 150A / m².

[0062] 4. Lithium precipitation: Heat the lithium-rich solution to 85°C, and add 1.08 times the amount of saturated Na2CO3 solution while stirring at 300 rpm. React for 1 hour, filter, wash with hot water, and then send the wet lithium carbonate into a spray drying tower with an inlet temperature of 200°C and an outlet temperature of 90°C to obtain the dried product.

[0063] 5. Treatment of three wastes: absorption of waste gas and alkaline solution, reuse of wastewater, and outsourcing of waste residue treatment;

[0064] Test results: The final product, lithium carbonate, has a chemical purity of 99.5%, a tap density of 1.8 g / cm³ (conventional product form), and a total lithium recovery rate of 89.8%. This example demonstrates that even without the use of ultrasound, deep purification can ensure extremely high chemical purity.

[0065] Example 3: Full-process optimization and integration (microwave + deep impurity removal + ultrasonic lithium deposition)

[0066] Take 2kg of waste ternary lithium batteries;

[0067] 1. Pretreatment and acid leaching: The positive electrode powder was obtained after disassembly and then subjected to microwave-assisted acid leaching (same as in Example 1).

[0068] 2. Multi-stage purification: First, add Ca(OH)2 to the leachate to adjust the pH to 5.0, precipitate and filter to remove Fe and Al, then add NaOH to adjust the pH to 10.5, precipitate and filter to remove Cu and other impurities. Subsequently, perform deep purification by adding 0.3 mol / L Na2CO3 solution to the filtrate, controlling the pH to 11.0, stirring and reacting at 60℃ for 0.5 hours, and filtering to remove Ca²⁺ and Mg²⁺.

[0069] 3. Enrichment and purification: Solvent extraction was used with 25% TBP-kerosene as the organic phase. The purified liquid was subjected to three-stage countercurrent extraction at an O / A ratio of 2:1, and back-extracted with 0.5 mol / L H2SO4 to obtain a high-purity lithium-rich solution.

[0070] 4. Lithium precipitation: In this embodiment, ultrasonic lithium precipitation is used. At the beginning of the lithium precipitation reaction, an ultrasonic probe is inserted into the reactor at a frequency of 28kHz and a power density of 150W / L. The reaction is carried out for 30 minutes. After filtration and washing with hot water, the wet lithium carbonate is sent into a spray drying tower with an inlet temperature of 200℃ and an outlet temperature of 90℃ to obtain the dried product.

[0071] 5. Waste treatment and resource utilization: The Na2SO4 solution produced by acid leaching waste gas absorption is combined with the lithium precipitation mother liquor, and industrial-grade Na2SO4 is produced by evaporation and crystallization. The wastewater is treated and reused, and all waste residues are centrally utilized for resource utilization.

[0072] Test results: The final product is uniform spherical lithium carbonate with a chemical purity of 99.8%, a tap density of up to 2.35 g / cm³, and a total lithium recovery rate of 91.5%. This product fully meets the requirements for high-performance lithium battery manufacturing.

[0073] The above embodiments fully demonstrate the advanced nature, flexibility, and reliability of the process of the present invention, especially the key roles of deep impurity removal in ensuring chemical purity, microwave assistance in improving efficiency, and ultrasonic lithium deposition combined with spray drying in improving the physical properties of the product.

[0074] Microwave-assisted acid leaching shortens reaction time and significantly reduces energy consumption. An innovative deep carbonate removal step is introduced to effectively remove difficult-to-treat alkaline earth metal impurities, ensuring the production of ultra-high purity lithium products. Through ultrasonic-assisted precipitation combined with spray drying, battery-grade lithium carbonate products with high sphericity and high tap density are directly obtained, meeting the requirements of high-end lithium battery manufacturing and greatly enhancing product value and market competitiveness. The entire process incorporates the concepts of resource utilization and harmlessness, achieving the coordinated treatment and recycling of waste gas, wastewater, and waste residue, resulting in significant environmental benefits.

[0075] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A process for deep impurity removal and lithium extraction from ternary lithium battery scrap, characterized by, The method comprises the following steps: Step 1: mechanical disassembly and physical sorting of ternary lithium battery waste, separating the positive plate, and obtaining lithium-rich positive powder after crushing and screening; Step 2: sulfuric acid leaching treatment is performed on the positive powder, and a reducing agent hydrogen peroxide is added to control the reaction temperature, time and liquid-solid ratio, so as to realize efficient leaching of lithium; Step 3: multi-stage purification treatment is performed on the acid leaching solution to remove iron, aluminum, copper, calcium and magnesium impurities in sequence; Step 4: enrichment and purification of lithium in the purified solution is performed by solvent extraction or electrodialysis method; Step 5: sodium carbonate is added to the lithium-rich solution to perform precipitation reaction to generate lithium carbonate, and battery-grade lithium carbonate product is obtained after washing and drying.

2. The process for deep impurity removal and lithium recovery from ternary lithium battery waste according to claim 1, characterized in that, In step 2, the sulfuric acid concentration is 2.0-3.0 mol / L, the volume fraction of hydrogen peroxide is 2-5%, the reaction temperature is 90-110℃, the time is 2-4h, the liquid-solid ratio is 4:1-6:1, and the acid excess coefficient is 1.1-1.

3.

3. The process for deep impurity removal and lithium recovery from ternary lithium battery waste according to claim 1, characterized in that, Step 3 specifically includes: First, add calcium hydroxide to adjust the pH to 4.5-5.5 to precipitate iron and aluminum; Then add sodium hydroxide to adjust the pH to 10-11 to further remove residual impurities.

4. The process for deep impurity removal and lithium recovery from ternary lithium battery waste according to claim 1, characterized in that, In step 4, the extractant is tributyl phosphate (TBP) kerosene system, the extraction phase ratio O / A is 1:1-3:1, and the back extraction agent is dilute sulfuric acid.

5. The process for deep impurity removal and lithium recovery from ternary lithium battery waste according to claim 1, wherein, In step 4, when using electrodialysis method, a selective ion exchange membrane is used, the operating voltage is 10-30V, and the current density is 50-200A / m².

6. The process for deep impurity removal and lithium recovery from ternary lithium battery waste according to claim 1, wherein, Step 5 specifically includes: controlling the reaction temperature to be 80-90℃, the stirring speed to be 200-400rpm, the precipitation time to be 1-2h, and the addition amount of the precipitant sodium carbonate to be 1.05-1.10 times of the theoretical amount.

7. The process for deep impurity removal and lithium recovery from ternary lithium battery waste according to claim 1, wherein, Step 2 also includes alkali absorption treatment of the acid waste gas generated during the acid leaching process, and the absorption liquid is sodium hydroxide solution, and the absorption generates sodium sulfate solution.

8. The process for deep impurity removal and lithium recovery from ternary lithium battery waste according to claim 1, wherein, Step 3 also includes microwave-assisted enhanced leaching, microwave power is 500-1000W, frequency is 2450MHz, auxiliary heating temperature is 90-110℃, and reaction time is shortened to 0.5-1.5h.

9. The process for deep impurity removal and lithium recovery from ternary lithium battery waste according to claim 1, wherein, Between step 3 and step 4, 0.1-0.5 mol / L sodium carbonate solution is added to the purified solution, the pH is controlled to be 10.5-11.5, the reaction temperature is controlled to be 50-70℃, and the stirring reaction is performed for 0.5-1h to deeply precipitate and remove calcium, magnesium and strontium alkaline earth metal ions in the solution.

10. The process for deep impurity removal and lithium recovery from ternary lithium battery waste according to claim 1, wherein, Step 5 is performed under the action of ultrasonic field, the ultrasonic frequency is 20-40kHz, the power density is 50-200 W / L, and the reaction time is 20-40 minutes; The primary lithium carbonate crystals are aged, spray dried to obtain battery-grade lithium carbonate product with high sphericity and tap density greater than 2.2 g / cm³.

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