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Method for preparing battery-grade lithium carbonate and iron phosphate by recycling lithium iron phosphate anode waste

A technology for lithium iron phosphate and waste recycling, applied in lithium carbonate;/acid carbonate, waste collector recycling, chemical instruments and methods, etc., can solve the problems of lithium recovery rate decline and large consumption, To achieve the effect of good product quality

Active Publication Date: 2020-12-29
UNIV OF SCI & TECH BEIJING +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the above methods all have a large consumption of acid and alkali, and produce a large amount of saline wastewater. A certain amount of lithium will be entrained during iron phosphate precipitation, resulting in a decline in the recovery rate of lithium.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Add the lithium iron phosphate positive electrode waste powder into water to make a slurry, blow in air and stir, and control the oxidation leaching conditions with a solid-liquid ratio of 500g / L, a reaction time of 1 hour, and a reaction temperature of 25°C. Slowly add oxalic acid during the process to maintain The pH is 5.0. After the reaction is completed, filter and separate, adjust the pH of the filtrate to 11 to precipitate and remove impurities, then heat the solution to 95°C, and add saturated sodium carbonate solution to precipitate lithium carbonate at the same time, and the filtered solid product is washed and dried to obtain lithium carbonate product. Add iron powder and a small amount of phosphoric acid to the water leaching slag and put it into a planetary ball mill for ball milling activation. The molar amount of iron powder added is 0.55 times the molar amount of iron in the water leaching slag, and the ball milling time is 1 hour; the product after ball ...

Embodiment 2

[0019] Add the lithium iron phosphate positive electrode waste powder into water to make a slurry, blow in air and stir, control the oxidation leaching condition with a solid-liquid ratio of 350g / L, a reaction time of 3 hours, and a reaction temperature of 50°C. Slowly add acetic acid during the process to maintain The pH is around 3.5. After the reaction is completed, solid-liquid separation is carried out to obtain lithium-containing solution and leaching residue, and the leaching rate of lithium is 98.9%. Adjust the pH of the filtrate to 11 to precipitate and remove impurities, then heat the solution to 95°C, and add saturated sodium carbonate solution to precipitate lithium carbonate at the same time, and the filtered solid product is washed and dried to obtain lithium carbonate product. Add iron powder to the water leaching slag and add a small amount of phosphoric acid into a planetary ball mill for ball milling activation. The molar amount of iron powder added is 0.575 ...

Embodiment 3

[0021] Add the lithium iron phosphate positive electrode waste powder into water to make a slurry, blow in air and stir, control the oxidation leaching condition with a solid-to-liquid ratio of 200g / L, a reaction time of 5 hours, and a reaction temperature of 90°C. Slowly add citric acid during the process Maintain pH around 4.0. After the reaction is completed, solid-liquid separation is carried out to obtain lithium-containing solution and leaching residue, and the leaching rate of lithium is 99.2%. Adjust the pH of the filtrate to 11 to precipitate and remove impurities, then heat the solution to 95°C, and add saturated sodium carbonate solution to precipitate lithium carbonate at the same time, and the filtered solid product is washed and dried to obtain lithium carbonate product. Add iron powder and a small amount of phosphoric acid to the water leaching slag and put it into a planetary ball mill for ball milling activation. The molar amount of iron powder added is 0.6 ti...

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Abstract

The invention relates to a method for preparing battery-grade lithium carbonate and iron phosphate by recycling lithium iron phosphate cathode waste, and belongs to the fields of electronic waste recycling and resourcing. According to the method, air is adopted as an oxidizing agent to oxidize lithium iron phosphate into iron phosphate, so that lithium is removed and enters a solution, and leaching of other impurity elements is little. A lithium solution is neutralized and precipitated to remove impurities, and saturated sodium carbonate is added to obtain a lithium carbonate product; and water leaching residues are mixed with iron powder and a small amount of phosphoric acid, ball-milling is implemented for activation reduction, a solid product obtained after activation is stirred and dissolved out by using a phosphoric acid solution, and an iron and phosphorus solution is obtained by filtering. The characteristic that ferric phosphate is low in solubility at high temperature is utilized, ferric phosphate sediment is obtained through a high-temperature evaporative crystallization method, and the ferric phosphate for the battery is obtained after aging, washing and calcining. The method has the advantages of cheap reagent, low acid consumption, high valuable element recovery rate, environmental friendliness and the like.

Description

technical field [0001] The invention relates to a method for preparing battery-grade lithium carbonate and iron phosphate by recycling lithium iron phosphate positive electrode waste, and belongs to the field of electronic waste recycling and recycling. Background technique [0002] As an energy storage device that converts chemical energy and electrical energy, lithium-ion batteries are the driving core of new energy vehicles. Due to its good safety, good cycle performance, stable voltage, and good rate performance, lithium iron phosphate batteries have been rapidly developed in the fields of power vehicles and energy storage. This means that a large amount of waste lithium iron phosphate batteries will be generated in the future. Harmful substances such as electrolytes contained in waste batteries will cause environmental pollution, and valuable metals such as lithium and iron contained in them will cause waste of resources if they are not recycled. Therefore, the recycl...

Claims

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Application Information

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IPC IPC(8): C01D15/08C01B25/37H01M4/58H01M10/54
CPCC01B25/375C01D15/08H01M4/5825H01M10/54Y02E60/10Y02W30/84
Inventor 张家靓王成彦王朵朵陈永强马保中张文娟金浩
Owner UNIV OF SCI & TECH BEIJING
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