CN116814984A - A method for extracting lithium from waste lithium iron phosphate batteries - Google Patents

Abstract

The invention discloses a method for extracting lithium from waste lithium iron phosphate batteries. The specific steps are as follows: 1) Crushing: the positive electrode materials recovered from the waste lithium iron phosphate batteries are crushed and screened to obtain fine lithium iron phosphate waste materials. Powder; 2) Roasting: Roast the lithium iron phosphate waste fine powder at high temperature in a rotary kiln, and then perform mechanical crushing and ball milling after roasting to obtain roasted and crushed fine powder; 3) Leaching back to remove impurities: Combine the roasted and crushed fine powder clinker with The acid solution is fully stirred for leaching, and the pH is adjusted back to solid-liquid separation to obtain a lithium-containing solution and leaching residue; 4) Purification solution: Add sodium hydroxide and sodium carbonate to the lithium-containing solution to remove impurities, and then use sodium carbonate to precipitate lithium to prepare battery grade Lithium carbonate. The method of the invention does not require the use of oxidant reagents, and has the advantages of low roasting temperature, low cost, simple process operation, etc. The rotary kiln can be used to process iron lithium powder on a large scale, and is suitable for industrial recycling of waste lithium iron phosphate batteries for lithium extraction, leaching and Impurities are removed at the same time, which simplifies the process flow, operating steps and saves equipment investment.

Description

A method for extracting lithium from waste lithium iron phosphate batteries

Technical field

The invention belongs to the technical field of lithium ion recovery, and specifically relates to a method for extracting lithium from waste lithium iron phosphate batteries.

Background technique

With the rapid development of the economy, the new energy vehicle industry has developed rapidly. As the main power source of new energy vehicles, lithium iron phosphate batteries have been produced and applied in large quantities. Because of its high safety factor, long cycle life and other excellent properties, it is widely used in starting power supply, energy storage market, military industry, navigation beacon and other fields. The widespread use of lithium iron phosphate batteries has led to an increase in scrapping year by year, causing serious problems such as wasting resources, polluting the environment, and endangering human health. Waste lithium iron phosphate batteries have low content of valuable metal lithium and poor recycling economics. Low-cost recycling has become a research hotspot. Although some results and applications have been achieved, there are still problems such as low recovery rate of valuable elements and high cost. Therefore, high-value all-element recycling of used lithium iron phosphate batteries has become the key and difficulty to solve the above problems.

In the prior art, CN106505225A discloses a method for recovering lithium from used lithium batteries to prepare battery-grade lithium carbonate. The main steps of the method include battery disassembly, acidification leaching, iron removal, aluminum, lithium fluoride precipitation, and magnesium salt transformation. , alkalization and impurity removal, soda ash lithium precipitation, etc. The core point is to add inorganic acid and hydrogen peroxide to the slurry, control the molar ratio of H ⁺ to Li ⁺ to 3:1~4:1, and control the molar ratio of hydrogen peroxide to Li ⁺ The ratio is 1:2~1:1, and then leached for 30-60 minutes at normal temperature to recover lithium; CN109534372A discloses a method for preparing lithium carbonate from lithium iron phosphate waste. Under normal temperature conditions, a certain mass of lithium iron phosphate waste is put into In the reaction vessel, a certain mass of sodium hypochlorite solution is added while stirring, and the molar ratio of Li and ^ClO is controlled to be 2:1.05-2:1.20 to obtain a mixed solution; the resulting mixed solution is slowly added while stirring, and the purity is 31-35%. Hydrochloric acid, the addition speed of hydrochloric acid is controlled at 5-10ml/min, adjust the pH of the solution to 1-2, after obtaining the acidic solution, stir the reaction at 80-90°C for 0.5-2h; then filter, rinse, concentrate and remove impurities , alkalization and impurity removal, soda ash lithium precipitation to recover lithium from lithium iron phosphate waste. It can be seen that the existing wet recovery method of lithium in waste lithium iron phosphate batteries uses an oxidant to oxidize Fe ²⁺ into Fe ³⁺ , and then adjusts the pH to co-precipitate with phosphate or hydroxide; and then in the filtrate A precipitant is added to precipitate Li ⁺ to achieve recovery of Li ⁺ . This method has good stability and high recovery rate, but it requires a large amount of oxidant to be consumed during the leaching process, resulting in high production costs and complicated processes.

Contents of the invention

In view of the shortcomings of the existing technology, the present invention provides a method for extracting lithium from waste lithium iron phosphate batteries. No additional oxidant is required during the leaching process. The recovery rate of lithium is ≥96.5%. It has large processing scale and simple process operation. , low cost, easy to achieve industrial production and other advantages.

A method for extracting lithium from waste lithium iron phosphate batteries. The specific steps are as follows:

1) Crushing: The cathode materials recovered by dismantling and recycling waste lithium iron phosphate batteries are crushed and then sieved to obtain fine powder of lithium iron phosphate scrap;

2) Roasting: Roast the lithium iron phosphate scrap fine powder at high temperature in a rotary kiln, and then perform mechanical crushing and ball milling after roasting to obtain roasted and crushed fine powder;

3) Leaching callback and impurity removal: fully stir the roasted and crushed fine clinker and the acid solution for leaching, call back the pH and separate the solid and liquid to obtain the lithium-containing solution and leaching residue;

4) Purify the solution: Add sodium hydroxide and sodium carbonate to the lithium-containing solution to remove impurities, and then use sodium carbonate to precipitate lithium to prepare battery-grade lithium carbonate.

Preferably, the lithium content of the lithium iron phosphate waste fine powder in step 1) is 2.5-4.4%, and the fineness is ≤60 mesh:

Preferably, in step 2), the roasting temperature of the rotary kiln is 400-800°C, and the roasting time is 0.5-4h.

Preferably, the fineness of the roasted and crushed fine powder in step 2) is 60-200 mesh.

Preferably, the acid solution in step 3) is at least one of sulfuric acid, hydrochloric acid, and acetic acid.

Preferably, the leaching temperature in step 3) is 30-80°C, the leaching time is 0.5-6.0h, the stirring intensity is 100-600rpm, and the pH of the solution after leaching is completed is 2-3.

Preferably, at least one of caustic soda and hydrated lime is used to adjust the pH in step 3), and the pH after the adjustment is 4-5.5.

Preferably, the impurity removal method in step 4) is to adjust the pH to 11-13 with sodium hydroxide and then add sodium carbonate to remove impurities according to the calcium and magnesium content in the solution and an excess of 5%.

Preferably, the temperature during the lithium precipitation process in step 4) is ≥85°C, and the sodium carbonate concentration is 180-300g/L.

Compared with the prior art, the present invention has the following advantages:

The invention provides a method for extracting lithium from waste lithium iron phosphate batteries. By roasting at medium temperature in a rotary kiln, the divalent iron in the lithium iron phosphate is oxidized into trivalent iron to destroy its stable structure, and then leached. The process does not require the use of oxidant reagents, and has the advantages of low roasting temperature, low cost, and simple process operation. The rotary kiln can process lithium iron powder on a large scale and is suitable for industrial recycling of waste lithium iron phosphate batteries to extract lithium. The method of the present invention leaches and removes lithium. The process is carried out simultaneously, which simplifies the process flow, operating steps and saves equipment investment. The recovery rate of lithium through the method of the present invention is ≥96.5%.

Implementation

The present invention will be further described in detail below in conjunction with specific embodiments.

Example 1

The cathode material recovered from the disassembly and recycling of waste lithium iron phosphate batteries is crushed and passed through a 60-mesh screen. The material under the screen is taken to obtain ≤60-mesh lithium iron phosphate waste fine powder, and then the lithium iron phosphate waste fine powder is processed in a rotary kiln. Roast at 600°C for 1.0h, cool to below 60°C and perform mechanical crushing and ball milling to 80 mesh. Then roast and crush the fine powder clinker and dilute sulfuric acid and stir and leach at 60°C for 1.0h. The stirring intensity is 400rpm, and the liquid-to-solid ratio is 3:1, the pH of the post-leaching liquid is controlled between 2-3. When the pH is high, add acid and continue the reaction until the pH stabilizes at 2-3 and there is no change within half an hour. The leaching reaction is completed. After the leaching reaction is completed, use caustic soda to adjust the reaction. After the pH is between 4 and 5.5, a plate and frame filter press is used to separate solid and liquid to obtain a lithium-containing solution and leaching residue; after washing the leaching residue, the lithium ion concentration in the residue is 0.03wt%, and the recovery rate of lithium is 97.2%; lithium-containing solution After adjusting the pH of the solution to 12 with sodium hydroxide, add sodium carbonate to remove calcium and magnesium ions according to the calcium and magnesium content in the solution and an excess of 5% to obtain a lithium-containing purification solution, and then use 260g/L sodium carbonate solution to precipitate lithium at 95°C. Obtain battery grade lithium carbonate.

Example

The cathode material recovered from the disassembly and recycling of waste lithium iron phosphate batteries is crushed and passed through a 60-mesh screen. The material under the screen is taken to obtain ≤60-mesh lithium iron phosphate waste fine powder, and then the lithium iron phosphate waste fine powder is processed in a rotary kiln. Roast at 400°C for 4.0h, cool to below 60°C and then perform mechanical crushing and ball milling to 100 mesh, then roast and crush the fine powder clinker and hydrochloric acid, stir and leaching at 60°C for 2.0h, the stirring intensity is 600rpm, and the liquid-to-solid ratio is 4 :1. The pH of the liquid after leaching is controlled between 2-3. When the pH is high, add acid and continue the reaction until the pH stabilizes at 2-3 and there is no change within half an hour. The leaching reaction is completed. After the leaching reaction is completed, use caustic soda to adjust the pH. After solid-liquid separation using a plate and frame filter press between 4 and 5.5, the lithium-containing solution and leaching residue are obtained; the lithium ion concentration in the leaching residue after washing is 0.05wt%, and the lithium recovery rate is 96.5%; the lithium-containing solution Use sodium hydroxide to adjust the pH to 13, then add sodium carbonate to remove calcium and magnesium ions according to the calcium and magnesium content in the solution and an excess of 5% to obtain a lithium-containing purification solution, and then use 280g/L sodium carbonate solution to precipitate lithium at 90°C to obtain Battery grade lithium carbonate.

Example

The cathode material recovered from the disassembly and recycling of waste lithium iron phosphate batteries is crushed and passed through a 60-mesh screen. The material under the screen is taken to obtain ≤60-mesh lithium iron phosphate waste fine powder, and then the lithium iron phosphate waste fine powder is processed in a rotary kiln. Roast at 700°C for 1.5h, cool to below 60°C and then perform mechanical crushing and ball milling to 150 mesh. Then roast and crush the fine powder clinker and dilute sulfuric acid and stir and leaching at 60°C for 2.0h. The stirring intensity is 600rpm, and the liquid-to-solid ratio is 5:1, the pH of the post-leaching liquid is controlled between 2-3. When the pH is high, add acid and continue the reaction until the pH stabilizes at 2-3 and there is no change within half an hour. The leaching reaction is completed. After the leaching reaction is completed, use caustic soda to adjust the reaction. After the pH is between 4 and 5.5, use a plate and frame filter press to separate the solid and liquid to obtain a lithium-containing solution and leaching residue; after washing the leaching residue, the lithium ion concentration in the residue is 0.02wt%, and the recovery rate of lithium is 98.6%; lithium-containing solution After adjusting the pH of the solution to 13 with sodium hydroxide, add sodium carbonate to remove calcium and magnesium ions according to the calcium and magnesium content in the solution and an excess of 5% to obtain a lithium-containing purification solution, and then use 275g/L sodium carbonate solution to precipitate lithium at 95°C. Obtain battery grade lithium carbonate.

The cathode material recovered from the disassembly and recycling of waste lithium iron phosphate batteries is crushed and passed through a 100-mesh screen. The material under the screen is taken to obtain ≤100-mesh lithium iron phosphate waste fine powder, and then the lithium iron phosphate waste fine powder and dilute sulfuric acid, The hydrogen peroxide is stirred and leached at 80°C for 10 hours. The dosage of 35% hydrogen peroxide is 1 ton of lithium iron phosphate waste fine powder plus 0.45 ton of hydrogen peroxide. The stirring intensity is 600 rpm, the liquid-to-solid ratio is 4:1, and the pH of the liquid after leaching is controlled at 2 -3. When the pH is high, add acid and continue the reaction until the pH stabilizes at 2-3 and there is no change within half an hour. The leaching reaction is completed. After the leaching reaction is completed, use caustic soda to adjust the pH to 4-5.5 and then use a plate and frame. After solid-liquid separation in the filter press, the lithium-containing solution and leaching residue are obtained; after washing, the lithium ion concentration in the leaching residue is 0.08wt%, and the lithium recovery rate is 91.4%; the lithium-containing solution is adjusted to pH 13 with sodium hydroxide. According to the calcium and magnesium content in the solution and an excess of 5%, sodium carbonate is added to remove calcium and magnesium ions to obtain a lithium-containing purification solution, and then lithium is precipitated with 280g/L sodium carbonate solution at 90°C to obtain battery-grade lithium carbonate.

The cathode material recovered from the disassembly and recycling of waste lithium iron phosphate batteries is crushed and passed through a 100-mesh screen. The material under the screen is taken to obtain ≤100-mesh lithium iron phosphate waste fine powder, and then the lithium iron phosphate waste fine powder and dilute sulfuric acid, Sodium chlorate is stirred and leached at 60°C for 4 hours. The dosage of sodium chlorate is 1 ton of lithium iron phosphate waste fine powder plus 0.12 ton of sodium chlorate. The stirring intensity is 600rpm, and the liquid-to-solid ratio is 4:1. After leaching, the liquid The pH is controlled between 2-3. When the pH is high, acid supplementation continues to react until the pH stabilizes at 2-3 and there is no change within half an hour before the leaching reaction is completed. After the leaching reaction is completed, use caustic soda to adjust the pH to between 4-5.5. After solid-liquid separation using a plate and frame filter press, the lithium-containing solution and leaching residue are obtained; the lithium ion concentration in the leaching residue after washing is 0.07wt%, and the lithium recovery rate is 95.6%; the pH of the lithium-containing solution is adjusted with sodium hydroxide. After 13 days, sodium carbonate is added to remove calcium and magnesium ions according to the calcium and magnesium content in the solution and an excess of 5% to obtain a lithium-containing purification solution, and then lithium is precipitated with 280g/L sodium carbonate solution at 90°C to obtain battery-grade lithium carbonate.

The above are only embodiments of the present invention. It should be noted that those of ordinary skill in the art can make various changes, modifications, replacements and modifications to these embodiments without departing from the technical principles of the present invention. Variations, these changes, modifications, replacements and modifications should also be regarded as the protection scope of the present invention.

Claims (9)

1. The method for extracting lithium from the waste lithium iron phosphate battery is characterized by comprising the following specific steps:

1) Crushing: crushing and sieving the positive electrode material recovered by disassembling the waste lithium iron phosphate battery to obtain lithium iron phosphate waste fine powder;

2) Roasting: roasting the lithium iron phosphate waste fine powder at a high temperature by a rotary kiln, and mechanically crushing and ball milling after roasting to obtain roasting and crushing fine powder;

3) Leaching callback impurity removal: fully stirring the roasting and crushing fine powder clinker and an acid solution to leach, adjusting the pH value, and then carrying out solid-liquid separation to obtain a lithium-containing solution and leaching residues;

4) Purifying solution: adding sodium hydroxide and sodium carbonate into the lithium-containing solution to remove impurities, and then precipitating lithium with sodium carbonate to prepare the battery grade lithium carbonate.

2. The method for extracting lithium from waste lithium iron phosphate batteries according to claim 1, wherein the lithium content of the lithium iron phosphate waste fine powder in the step 1) is 2.5-4.4%, and the fineness is less than or equal to 60 meshes.

3. The method for extracting lithium from waste lithium iron phosphate batteries according to claim 1, wherein the roasting temperature of the rotary kiln in the step 2) is 400-800 ℃ and the roasting time is 0.5-4h.

4. The method for extracting lithium from waste lithium iron phosphate batteries according to claim 1, wherein the fineness of the roasting and crushing fine powder in the step 2) is 60-200 meshes.

5. The method for extracting lithium from waste lithium iron phosphate batteries according to claim 1, wherein the acid solution in the step 3) is at least one of sulfuric acid, hydrochloric acid and acetic acid.

6. The method for extracting lithium from waste lithium iron phosphate battery according to claim 1, wherein the leaching temperature in the step 3) is 30-80 ℃, the leaching time is 0.5-6.0h, the stirring intensity is 100-600rpm, and the pH of the solution after leaching is 2-3.

7. The method for extracting lithium from the waste lithium iron phosphate battery according to claim 1, wherein the step 3) is performed with at least one of caustic soda and slaked lime, and the pH after the callback is 4-5.5.

8. The method for extracting lithium from waste lithium iron phosphate batteries according to claim 1, wherein the impurity removal method in the step 4) is to remove impurities by adjusting the pH to 11-13 with sodium hydroxide and adding sodium carbonate according to the content of calcium and magnesium in the solution and 5% excess.

9. The method for extracting lithium from waste lithium iron phosphate batteries according to claim 1, wherein the temperature in the lithium precipitation process in the step 4) is not less than 85 ℃, and the concentration of sodium carbonate is 180-300g/L.