CN117446769A - A method for recycling waste lithium iron manganese phosphate batteries - Google Patents

Abstract

The invention discloses a method for recycling waste lithium manganese iron phosphate batteries, which can realize full-component recycling of the positive electrode material of the waste lithium manganese iron phosphate batteries through coupling of technologies such as leaching, impurity removal, extraction and the like, and the obtained products of ferric phosphate, lithium carbonate and manganese sulfate have high purity and high recovery rate of metals. The invention has simple process, convenient operation and safe and reliable production process.

Description

A method for recycling waste lithium iron manganese phosphate batteries

Technical field

The invention belongs to the field of lithium-ion battery recycling, and specifically relates to a method for recycling waste lithium iron manganese phosphate batteries.

Background technique

The voltage platform of lithium manganese phosphate is much higher than that of lithium iron phosphate, but it has problems such as extremely low conductivity, poor cycle performance and irreversible damage to the molecular structure, and is rarely used. Adding manganese element to lithium iron phosphate to improve the voltage platform has become a key breakthrough. The ionic radii of manganese ions and iron ions are close and they can be miscible in any proportion. Therefore, by adding manganese element to lithium iron phosphate and adjusting its ratio to iron, a high voltage platform can be achieved while avoiding the inherent defects of lithium manganese phosphate. The product at this time is lithium manganese iron phosphate. Therefore, lithium iron manganese phosphate is a cathode material obtained by adding manganese element to traditional lithium iron phosphate in order to obtain a high-voltage platform for lithium manganese phosphate.

At present, the recycling of used ternary lithium batteries and lithium iron phosphate batteries has been industrialized. Due to the different components, the recycling process of ternary lithium batteries and lithium iron phosphate batteries cannot be directly applied to the recycling process of lithium manganese iron phosphate. However, along with the phosphoric acid With the release of lithium iron manganese production capacity and its gradual use in electric vehicle power batteries, there is an urgent need to develop a process that is low-cost, simple to operate, and easy to realize industrialized recycling of used lithium iron manganese phosphate batteries.

Contents of the invention

The object of the present invention is to overcome the above technical deficiencies and provide a method for recycling waste lithium iron manganese phosphate batteries, which is simple, efficient and easy to industrially recycle waste lithium iron manganese phosphate batteries.

In order to achieve the above technical objectives, the technical solution of the present invention provides a method for recycling waste lithium iron manganese phosphate batteries, which includes the following steps: Step 1: Discharge, dismantle, crush and screen the waste lithium iron manganese phosphate batteries in sequence. , separate to obtain the lithium iron manganese phosphate battery cathode material; Step 2: Mix water and lithium iron manganese phosphate cathode material and stir to slurry to obtain a slurry; heat the slurry and then add acid solution for leaching, and after the leaching is completed, the solid and liquid are separated , obtain leaching residue and leaching liquid A; Step 3: Adjust the pH value of leaching liquid A to 2-3, remove copper and aluminum, and then obtain impurity-removed liquid B through solid-liquid separation; Step 4: Measure impurity-removing liquid B Medium element content, according to the ratio of iron and phosphorus, add ammonium phosphate to the impurity removal liquid B to adjust the iron-phosphorus ratio, add hydrogen peroxide for oxidation, and adjust the pH of the solution to precipitate iron phosphate. After solid-liquid separation, iron phosphate precipitation and lithium-containing iron are obtained. , solution C of manganese; Step 5: Extract the solution C containing lithium and manganese through P204 to obtain the raffinate and loaded organic phase; the loaded organic phase is then washed with acid solution and stripped to obtain the stripped liquid; wherein, the extraction liquid The remaining liquid is lithium-containing solution D, and the stripping liquid is manganese-containing solution E; Step 6: Evaporate and concentrate the lithium-containing solution D, then adjust the pH to 10-11, add ammonium carbonate to precipitate lithium, and solid-liquid separation obtains lithium carbonate precipitation; The manganese-containing solution E is evaporated, concentrated and crystallized to obtain manganese sulfate.

Compared with the existing technology, the beneficial effects of the present invention include:

Through the coupling of leaching, impurity removal, extraction and other technologies, the present invention can realize full-component recovery of waste manganese iron phosphate lithium battery cathode materials. The obtained iron phosphate, lithium carbonate and manganese sulfate products have high product purity and metal recovery. The rate is also high. The invention has simple process, convenient operation and safe and reliable production process.

Description of the drawings

Figure 1 is a process flow diagram of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.

Referring to Figure 1, the present invention provides a method for recycling waste lithium iron manganese phosphate batteries, which includes the following steps:

Step 1: The waste lithium iron manganese phosphate batteries are discharged in salt water, dismantled, crushed and passed through a 200 mesh sieve in order to separate the cathode material of the lithium iron manganese phosphate battery with a copper content of less than 0.4% and an aluminum content of less than 0.3%;

Step 2: Mix water and lithium iron manganese phosphate cathode material according to a certain liquid-to-solid ratio and stir to form a slurry. After the slurry is raised to a certain temperature, sulfuric acid is added for leaching. After the leaching is completed, the solid and liquid are separated to obtain leaching residue and leaching liquid A. The leaching residue is treated as solid waste;

Step 3: Adjust the pH value of leach solution A to 2 to 3, remove copper and aluminum, and then perform solid-liquid separation to obtain impurity-removed solution B;

Step 4: Use ICP to measure the element content in the impurity removal liquid B. Add ammonium phosphate to the impurity removal liquid B according to the ratio of iron and phosphorus to adjust the iron to phosphorus molar ratio to 1:1. Add hydrogen peroxide for oxidation. The molar ratio of hydrogen peroxide to iron is (1 ~ 1.5): 2. During the process, the pH of the solution is adjusted to precipitate iron phosphate. After solid-liquid separation, iron phosphate precipitation and solution C containing lithium and manganese are obtained;

Step 5: Extract manganese from solution C containing lithium and manganese through an extraction agent obtained by diluting P204 (bis(2-ethylhexyl) phosphate ester with solvent oil (sulfonated kerosene, etc.)), where the volume concentration of the extraction agent is 40 % ~ 65% extraction, the volume ratio of solution C and extraction agent can be selected according to the situation, and is not limited here; the lithium-containing raffinate and the loaded manganese organic phase are obtained; the loaded organic phase is then washed and back-extracted with acid solution to obtain Stripping liquid; wherein, the raffinate is lithium-containing solution D, and the stripping liquid is manganese-containing solution E;

Step 6: Evaporate and concentrate the lithium-containing solution D to a lithium content of 9-12g/L, add ammonia water to adjust the pH to 10-11, add ammonium carbonate to precipitate lithium, the molar ratio of lithium to ammonium carbonate is 2:1.1, and solid-liquid separation is performed to obtain carbonic acid. Lithium precipitates; the manganese-containing solution E is evaporated, concentrated and crystallized to obtain manganese sulfate.

Preferably, in step one, the waste lithium iron manganese phosphate battery refers to a waste battery pack or a waste single battery.

Preferably, in step two, the liquid-to-solid ratio of water and the lithium iron manganese phosphate cathode material is 3 to 5L/kg; too low a liquid-to-solid ratio will reduce the ion leaching rate, and too high a ratio will result in low leaching ion concentration, which is not conducive to Subsequent processes.

Preferably, in step two, the slurry is heated to 60-100°C and then sulfuric acid is added; the leaching time after adding sulfuric acid is 2-6 hours. If the reaction temperature is too low and the reaction time is too long, the leaching efficiency will be reduced.

Further preferably, the sulfuric acid concentration is 4-10 mol/L sulfuric acid solution; the acid-material molar ratio is 1.1-1.5, that is, the actual molar amount of sulfuric acid is the amount of metal elements (mainly lithium iron manganese) in the cathode material of the lithium iron manganese phosphate battery. ) is converted into 1.1 to 1.5 of the theoretical molar amount of sulfate.

Preferably, in step three, ammonia water is added to the leach solution to adjust the pH value to 2-3.

Preferably, in step three, iron powder is first added to replace the copper, and then ammonium fluoride is added to perform precipitation and aluminum removal.

Further preferably, the actual added amount of iron powder is 1.05 to 1.3 times the theoretical added amount; the actual added amount of ammonium fluoride is 1.5 to 2 times the theoretical added amount.

Preferably, in step four, ammonia water is used to adjust the pH value of the solution to 2-4 to precipitate iron phosphate.

Preferably, in step 5, through bis(2-ethylhexyl)phosphate extraction, the extraction level is 8 to 15 levels, the washing level is 5 to 10 levels, and the stripping level is 4 to 8 levels.

Preferably, in step five, a 0.2-1 mol/L sulfuric acid solution is used for washing, and a 2-6 mol/L sulfuric acid solution is used for stripping.

The sixth step is to adjust the pH value of the lithium-containing solution to 10-11.

Preferably, the ammonia water refers to an ammonia water solution with a concentration of 18%-32%.

Example 1

A method for recycling waste lithium iron manganese phosphate batteries, the steps are as follows:

Step 1: Separate the lithium iron manganese phosphate cathode material

The waste lithium iron manganese phosphate batteries are discharged, dismantled, crushed and screened in order to separate the cathode materials of lithium iron manganese phosphate batteries with a copper content of less than 0.4% and an aluminum content of less than 0.3%;

Step 2: Leaching of lithium iron manganese phosphate

Mix the lithium iron manganese phosphate cathode material with water and stir to form a slurry. The liquid-to-solid ratio is 4L/kg. After the slurry is raised to 90°C, 6 mol/L sulfuric acid is added for leaching for 4 hours. The acid-to-material ratio is 1.3; after the leaching is completed Solid-liquid separation is performed to obtain leaching residue and leaching liquid A;

Step 3: Remove copper and aluminum impurities

Add ammonia to leach solution A to adjust the pH to 2.5, add 1.1 times the theoretical amount of iron powder to replace the copper, continue to add 1.8 times the theoretical amount of ammonium fluoride to precipitate and remove aluminum, and separate the solid and liquid to obtain impurity-removed liquid B;

Step 4: Precipitate iron phosphate

Use ICP to measure the element content in the impurity removal liquid B. Add ammonium phosphate to the impurity removal liquid B according to the ratio of iron and phosphorus to adjust the iron to phosphorus molar ratio to 1:1. Add hydrogen peroxide for oxidation. The molar ratio of hydrogen peroxide to iron is 1: 2. During the process, use ammonia to adjust the pH value of the solution to 3 to precipitate iron phosphate. After solid-liquid separation, iron phosphate precipitation and solution C containing lithium and manganese are obtained;

Step 5: Bis(2-ethylhexyl)phosphate extraction

Extract solution C containing lithium and manganese through an extractant. The extractant is di(2-ethylhexyl) phosphate diluted with sulfonated kerosene. The volume concentration is 50%. The volume ratio of solution C to the extractant can be 1 :1, the extraction level is 10 levels, the washing level is 8 levels, and the stripping level is 5 levels. 0.4mol/L sulfuric acid is used for washing, 2mol/L sulfuric acid is used for stripping, and the raffinate is lithium-containing solution D. The stripping solution is manganese-containing solution E;

Step 6: Precipitate lithium carbonate and manganese sulfate

Evaporate and concentrate the lithium-containing solution D until the lithium content is 10g/L, add ammonia water to adjust the pH to 10-11, add ammonium carbonate to precipitate lithium, the molar ratio of lithium to ammonium carbonate is 2:1.1, and solid-liquid separation obtains lithium carbonate precipitation; Manganese-containing solution E is evaporated, concentrated and crystallized to obtain manganese sulfate.

The obtained iron phosphate, lithium carbonate, and manganese sulfate products are dried and weighed, and the purity of the products is analyzed; liquid B after impurity removal is taken to analyze the copper and aluminum ion content (measured by ICP).

The analysis results are as follows: the purity of the iron phosphate product reaches 95.52%; the purity of the lithium carbonate product reaches 97.89%; and the purity of the manganese sulfate product reaches 99.70%. Compared with the lithium iron manganese phosphate cathode material, the recovery rate of iron reaches 96.80%; the recovery rate of lithium reaches 94.85%; and the recovery rate of manganese reaches 90.85%. The copper and aluminum contents in liquid B after impurity removal are 3ppm and 5ppm respectively.

Example 2

Step 1: Separate the lithium iron manganese phosphate cathode material

Discharge, dismantle, crush and screen used lithium iron manganese phosphate batteries to separate out the cathode materials of lithium iron manganese phosphate batteries with copper content less than 0.4% and aluminum content less than 0.3%;

Step 2: Leaching of lithium iron manganese phosphate

Mix the lithium iron manganese phosphate cathode material with water and stir to form a slurry. The liquid-to-solid ratio is 5L/kg. After the slurry is raised to 90°C, 6 mol/L sulfuric acid is added for leaching for 4 hours. The acid-to-material ratio is 1.3; after the leaching is completed Solid-liquid separation is performed to obtain leaching residue and leaching liquid A;

Step 3: Remove copper and aluminum impurities

Add ammonia to leach solution A to adjust the pH to 2, add 1.1 times the theoretical amount of iron powder to replace the copper and remove copper, continue to add 1.8 times the theoretical amount of ammonium fluoride to precipitate and remove aluminum, and separate the solid and liquid to obtain impurity-removed liquid B;

Step 4: Precipitate iron phosphate

Use ICP to measure the element content in the impurity removal liquid B. Add ammonium phosphate to the impurity removal liquid B according to the ratio of iron and phosphorus to adjust the iron to phosphorus molar ratio to 1:1. Add hydrogen peroxide for oxidation. The molar ratio of hydrogen peroxide to iron is 1: 2. During the process, use ammonia to adjust the pH value of the solution to 3 to precipitate iron phosphate. After solid-liquid separation, iron phosphate precipitation and solution C containing lithium and manganese are obtained;

Step 5: Bis(2-ethylhexyl)phosphate extraction

Solution C containing lithium and manganese is extracted through an extraction agent. The extraction agent is di(2-ethylhexyl) phosphate diluted with solvent oil. The volume concentration is 50%. The volume ratio of solution C to the extraction agent can be 1: 1. The extraction level is 10, the washing level is 8, and the stripping level is 5. Washing uses 1mol/L sulfuric acid, stripping uses 4mol/L sulfuric acid, and the raffinate is lithium-containing solution D. Stripping The liquid is manganese-containing solution E;

Step 6: Precipitate lithium carbonate and manganese sulfate

Evaporate and concentrate the lithium-containing solution D until the lithium content is 10g/L, add ammonia water to adjust the pH to 10-11, add ammonium carbonate to precipitate lithium, the molar ratio of lithium to ammonium carbonate is 2:1.1, and solid-liquid separation obtains lithium carbonate precipitation; Manganese-containing solution E is evaporated, concentrated and crystallized to obtain manganese sulfate.

The obtained iron phosphate, lithium carbonate, and manganese sulfate products are dried and weighed, and the purity of the products is analyzed; liquid B after impurity removal is taken to analyze the copper and aluminum ion content (measured by ICP).

The analysis results are as follows: the purity of the iron phosphate product reaches 93.42%; the purity of the lithium carbonate product reaches 95.68%; and the purity of the manganese sulfate product reaches 97.80%. The recovery rate of iron reaches 96.55%; the recovery rate of lithium reaches 92.34%; the recovery rate of manganese reaches 92.26%. The copper and aluminum contents in liquid B after impurity removal are 8ppm and 10ppm respectively.

Comparative example 1

Compared with Example 1, the only difference is that the ammonium fluoride aluminum removal step is omitted, and other steps and conditions are the same as Example 1.

It was found that during the extraction process, aluminum and manganese would be extracted together, which ultimately resulted in the resulting manganese sulfate solution containing too high an aluminum impurity content, with the aluminum content rising from 10 ppm to 568 ppm.

Comparative example 2

Compared with Example 2, the only difference is that the liquid-to-solid ratio in step 2 is 2L/kg, and other steps and conditions are the same as in Example 2.

It was found that the recovery rate of metals will be significantly reduced, with the recovery rate of iron being 85.23%; the recovery rate of lithium being 80.45%; and the recovery rate of manganese being 83.56%.

Compared with the existing technology, the present invention can achieve full-component recovery of waste lithium iron manganese phosphate battery cathode materials through the coupling of leaching, impurity removal, extraction and other technologies, and obtain iron phosphate, lithium carbonate, and manganese sulfate products. , the product purity is high and the metal recovery rate is also high. Among them, the purity of iron phosphate product reaches 93.42% ~ 95.52%; the purity of lithium carbonate product reaches 95.68% ~ 97.89%; the purity of manganese sulfate product reaches 97.80% ~ 99.70%. The recovery rate of iron reaches 96.55% ~ 96.80%; the recovery rate of lithium reaches 92.34% ~ 94.85%; the recovery rate of manganese reaches 90.85% ~ 92.26%. The invention has simple process, convenient operation and safe and reliable production process.

The above-described specific embodiments of the present invention do not limit the scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.

Claims (10)

1. The method for recycling the waste lithium iron manganese phosphate battery is characterized by comprising the following steps of:

step one: sequentially discharging, disassembling, crushing and screening the waste lithium manganese iron phosphate batteries, and separating to obtain a lithium manganese iron phosphate battery anode material;

step two: mixing water with a lithium iron manganese phosphate anode material, stirring and pulping to obtain slurry; heating the slurry, adding acid liquor for leaching, and carrying out solid-liquid separation after leaching to obtain leaching slag and leaching liquor A;

step three: regulating the pH value of the leaching solution A to 2-3, removing copper and aluminum, and carrying out solid-liquid separation to obtain a purified solution B;

step four: measuring the element content in the solution B after impurity removal, adding ammonium phosphate into the solution B after impurity removal according to the proportion of iron and phosphorus to adjust the mole ratio of iron to phosphorus, adding hydrogen peroxide to oxidize, adjusting the pH of the solution to precipitate ferric phosphate, and carrying out solid-liquid separation to obtain ferric phosphate precipitate and a solution C containing lithium and manganese;

step five: extracting the solution C containing lithium and manganese by P204 to obtain raffinate and a loaded organic phase; washing and back-extracting the loaded organic phase with acid liquor to obtain back-extraction liquid; wherein the raffinate is lithium-containing solution D, and the strip liquor is manganese-containing solution E;

step six: evaporating and concentrating the lithium-containing solution D, adjusting the pH value to 10-11, adding ammonium carbonate to precipitate lithium, and carrying out solid-liquid separation to obtain lithium carbonate precipitate; and evaporating, concentrating and crystallizing the manganese-containing solution E to obtain manganese sulfate.

2. The method for recycling the waste lithium iron manganese phosphate battery according to claim 1, wherein in the second step, the liquid-solid ratio of water to the lithium iron manganese phosphate positive electrode material is 3-5L/kg.

3. The method for recycling the waste lithium iron manganese phosphate battery according to claim 1, wherein in the second step, the slurry is heated to 60-100 ℃ and then is leached for 2-6 hours by adding acid liquor.

4. The method for recycling the waste lithium iron manganese phosphate battery according to claim 1, wherein in the second step, the acid solution adopted in leaching is sulfuric acid solution with the acid solution mol/L of 4-10 mol/L, and the acid-material ratio is 1.1-1.5.

5. The method for recycling the waste lithium iron manganese phosphate battery according to claim 1, wherein in the third step, iron powder is added for replacing copper removal, and ammonium fluoride is added for precipitation aluminum removal.

6. The method for recycling the waste lithium iron manganese phosphate battery according to claim 5, wherein the actual addition amount of the iron powder is 1.05-1.3 times of the theoretical addition amount; the actual addition amount of the ammonium fluoride is 1.5 to 2 times of the theoretical addition amount.

7. The method for recycling the waste lithium iron manganese phosphate battery according to claim 1, wherein in the fifth step, the extraction level is 8-15, the washing level is 5-10, and the stripping level is 4-8.

8. The method for recycling the waste lithium iron manganese phosphate battery according to claim 1, wherein in the fifth step, P204 is diluted to a volume concentration of 40-65% by solvent oil during extraction; washing adopts 0.2-1 mol/L sulfuric acid solution, and back extraction adopts 2-6 mol/L sulfuric acid solution.

9. The method for recycling the waste lithium iron manganese phosphate battery according to claim 1, wherein the reagents used for adjusting the pH value are ammonia water; and in the fourth step, the pH value of the solution is regulated to 2-4 to precipitate ferric phosphate.

10. The method for recycling the waste lithium iron manganese phosphate battery according to claim 1, wherein in the sixth step, the lithium-containing solution D is evaporated and concentrated until the lithium content is 9-12 g/L, and then the pH value is adjusted; the molar ratio of lithium to ammonium carbonate was 2:1.1.