Recycling method of waste lithium iron phosphate battery

Abstract

The invention relates to a waste lithium iron phosphate battery recovery method, which comprises: preparing waste lithium iron phosphate battery into electrode active material powder, carrying out alkali washing, filtering, and drying to obtain a to-be-treated material; leaching the obtained material by adopting dilute acid and an oxidizing agent, and filtering to obtain lithium-rich leachate and filter residues; the obtained lithium-rich leachate is subjected to purification and impurity removal, and lithium precipitation is performed to obtain lithium carbonate; carrying out alkaline leaching on the obtained filter residues, and filtering to obtain a phosphorus-rich leachate and iron-rich residues; the obtained iron-rich slag is subjected to medium-temperature calcination; and evaporating and crystallizing or purifying and removing impurities from the obtained phosphorus-rich leachate, and then adding a solution containing hydrogen peroxide and Fe < 2 + > salt. According to the method, a two-step recycling process is adopted, lithium in the waste iron phosphate is extracted through dilute acid leaching, then the thought that a low-added-value iron open source is adopted for the ferrophosphorus slag is adopted, the leaching solution is purified and subjected to impurity removal, then battery-grade lithium carbonate or iron phosphate or high-purity sodium phosphate is obtained, and low-cost recycling and reusing of valuable metal in the waste lithium ion battery are efficiently achieved.

Description

technical field [0001] The invention relates to the technical field of recycling waste batteries, in particular to a method for recycling waste lithium iron phosphate batteries. Background technique [0002] With the rapid development of modern science and technology, the problem of social energy and environmental ecological pollution has become increasingly prominent, and the environmental and ecological pollution of various waste batteries has become the focus of social attention. Lithium-ion batteries are widely used in power batteries and energy storage batteries due to their high capacity, stable cycle performance, and high working platform voltage. Power and energy storage batteries usually require more battery materials than conventional small batteries. Therefore, in the next 3-5 years, a large number of lithium-ion batteries will be scrapped, and their recycling has high social value. [0003] However, at present, there are still defects in the domestic technical r...

AI Technical Summary

Problems solved by technology

[0003] However, at present, there are still defects in the domestic technical route of recycling waste lithium iron phosphate. The mainstream way to deal with the electrode active materials of waste lithium iron phosphate batteries is acidic reduction leaching to obtain Li + , Fe 2+ 、PO 4 3- , F - 、Al 3+ and Fe 3+ Plasma leaching solution, precipitation to remove aluminum, adsorption to remove fluorine, then adjust the pH value and add oxidant to precipitate to obtain FePO 4 , and finally adjust the pH and add Na 2 CO 3 get Li 2 CO 3

For example, "A Method for Preparing Lithium Iron Phosphate Cathode Material from Waste Lithium Iron Phosphate Batteries" announced by Chinese patent CN111009660B uses acid leaching-precipitation method to recover valuable metals in waste Lithium iron phosphate batteries, and first uses inorganic acid to leach electrode active materials Obtain the leaching solution, iron powder is replaced to remove copper, precipitate and remove aluminum, then add alkali and oxidant to control the pH value to obtain iron phosphate, and finally recover lithium. This method realizes the recovery of waste lithium iron phosphate, but the purity of the recovered product is not high , The problem of low lithium recovery rate

Another example is the "Comprehensive Recovery Method for Waste Lithium Iron Phosphate Battery Positive Electrode Materials" published by Chinese patent CN110459828A. Dilute acid and oxidant are used to leach waste lithium iron phosphate battery pole powder to obtain lithium enrichment solution, which is then purified and removed by precipitation to obtain lithium carbonate. ; FePO is obtained after acid leaching purification and impurity removal on the leaching slag 4 , this method realizes the recycling of waste lithium iron phosphate batteries, but the acid leaching of the pre-extracted lithium leaching residue must strictly control the reduction conditions to prevent Fe 3+ generation, and in Fe 2+ It is difficult to remove impurities from the solution under existing conditions

[0004] There is also a method to peel off the positive electrode sheet to obtain the positive electrode material, and then carry out acid leaching or pre-extraction of lithium to obtain a leaching solution containing Li, Fe and P or to obtain a Li-rich leaching solution and leaching residue, and pre-extract Fe from the leaching solution. , P and then extract Li or directly extract Li, this method has the difficulty of thoroughly removing impurities and purifying the leaching solution, the purity of the recovered product is not ideal, and the Fe and P in the pre-extracted lithium leaching slag all enter the solution, which will lead to purification difficulties

[0005] The existing conventional positive electrode material recovery method is easy to cause lithium loss, and the lithium recovery rate is not high. In addition, it is difficult to remove impurities in the iron-containing leachate during the recovery process, and it is difficult to obtain battery-grade iron phosphate that meets industry standards.

Images