CN-121976045-A - Low-cost green efficient lithium extraction method for waste lithium iron phosphate anode material

Abstract

The invention belongs to the technical field of lithium battery recovery, and in particular relates to a low-cost, green and efficient lithium extraction method for a waste lithium iron phosphate anode material, which comprises the steps of mixing waste lithium iron phosphate anode powder with water, adding an oxidant, stirring to obtain a leaching system, dropwise adding acid liquor to maintain the pH value of the leaching system within 2.6-4.5, and simultaneously introducing oxidizing gas into the leaching system; after leaching, carrying out solid-liquid separation to obtain the lithium-rich leaching solution. The invention can realize the high-efficiency selective leaching of lithium by only a small amount of acid and oxidant, the leaching rate of lithium can reach 99.5%, the reagent cost is greatly reduced, and the lithium can be preferentially extracted even at normal temperature and low temperature, and the invention has the advantages of short process flow, low cost, strong adaptability, greenness and high efficiency and large industrialized application potential.

Inventors

• WANG QIANG
• LONG CHENG
• ZOU QIAN
• ZHANG DONGMEI
• XU ZHIGANG
• LV WENQIANG
• LIU GUANGLIANG
• CAI WEISONG
• WANG TIANWEI
• LI RENPENG
• Luo Tingmei
• YU JING
• YE PEILIN

Assignees

• 重庆康普化学工业股份有限公司

Dates

Publication Date

20260505

Application Date

20260107

Claims (9)

1. 1. A low-cost, green and efficient lithium extraction method for a waste lithium iron phosphate anode material is characterized by comprising the following steps of: Mixing waste lithium iron phosphate anode powder with water, adding an oxidant, stirring to obtain a leaching system, dropwise adding acid liquor to maintain the pH value of the leaching system within 2.6-4.5, simultaneously introducing oxidizing gas into the leaching system, and carrying out solid-liquid separation after leaching to obtain the lithium-rich leaching solution.
2. 2. The method for extracting lithium from the waste lithium iron phosphate anode material with low cost, green and high efficiency according to claim 1, wherein the oxidant is one or more of sodium percarbonate, sodium perborate, hydrogen peroxide, sodium hypochlorite, sodium perchlorate, sodium chlorate, sodium chlorite, ammonium peroxodisulfate, sodium peroxodisulfate and potassium peroxodisulfate.
3. 3. The method for extracting lithium from the waste lithium iron phosphate anode material with low cost, green and high efficiency of claim 1, wherein the oxidizing gas comprises one or more of air, oxygen and ozone.
4. 4. The method for extracting lithium from the waste lithium iron phosphate anode material with low cost, green and high efficiency according to claim 1, wherein the acid solution is one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid and acetic acid.
5. 5. The method for extracting lithium from the waste lithium iron phosphate anode material with low cost, green and high efficiency is characterized in that the dosage ratio of the waste lithium iron phosphate anode powder to water is 20-300 g/L.
6. 6. The low-cost, green and efficient lithium extraction method for the waste lithium iron phosphate anode material is characterized in that the mass ratio of the waste lithium iron phosphate anode powder to the oxidant is 1:0.1-3.
7. 7. The method for extracting lithium from the waste lithium iron phosphate anode material with low cost, green and high efficiency is characterized in that the flow rate of the oxidizing gas is 0.5-10L/min.
8. 8. The method for extracting lithium from the waste lithium iron phosphate anode material with low cost, green and high efficiency is characterized in that the particle size of the waste lithium iron phosphate anode powder is 10-200 mu m.
9. 9. The low-cost, green and efficient lithium extraction method for the waste lithium iron phosphate anode material is characterized in that the leaching time is 60-180 min, the leaching temperature is 1-50 ℃, and the leaching stirring speed is 100-400 rpm.

Description

Low-cost green efficient lithium extraction method for waste lithium iron phosphate anode material Technical Field The invention belongs to the technical field of lithium battery recovery, and particularly relates to a low-cost, green and efficient lithium extraction method for a waste lithium iron phosphate anode material. Background Along with global energy transformation acceleration, lithium ion batteries are in explosive growth in the fields of electric automobiles and energy storage. Among them, lithium iron phosphate batteries (LiFePO 4, LFP) have been used in the market of power batteries in a proportion of 72% or more because of their advantages of high safety, long cycle life, low cost, and the like. However, the lithium iron phosphate battery generally has a service period of only 5-8 years, and how to efficiently recycle strategic metal resources in the waste batteries has become a core proposition. The current waste LFP recovery still faces serious challenges in terms of technology and cost, and the traditional hydrometallurgical process consumes a large amount of strong acid and oxidant, so that a large amount of iron, aluminum, phosphorus and the like are co-dissolved, and the subsequent lithium passivation step is complex, high in cost and high in yield loss. The invention discloses a method for recycling all elements of a waste lithium iron phosphate battery anode material, which comprises the steps of mixing lithium iron phosphate powder with hydrogen peroxide solution, adding dilute hydrochloric acid for leaching, adjusting the pH value to 3.5-4, and obtaining a liquid which is a lithium-rich solution through solid-liquid separation. The method has the advantages that lithium, iron and phosphorus are leached, the pH value of the leaching end point is low, the selective extraction effect of lithium is poor, alkali is added to adjust the pH value to precipitate and remove impurities, the reagent cost is increased, and the wastewater is large. The invention of China with publication number CN120573660A discloses a method for treating waste ferric phosphate anode materials by a phosphoric acid-hydrogen peroxide method and a specific complexing agent, according to the treatment method, lithium, iron and phosphorus are leached, the pH value of the leaching end point is low, alkali is required to be added to adjust the pH value to 2.5-3.5, and a complexing agent is required to be added, so that the reagent cost is increased. The Chinese patent with publication number CN120505515A discloses a method for recovering aluminum, iron and lithium from waste lithium iron phosphate batteries, which utilizes sulfuric acid and hydrogen peroxide to fully dissolve lithium iron phosphate at 50-60 ℃ for separation, and has the advantages of complex flow and high cost. The Chinese patent with publication number CN120423511A discloses a method for recycling waste lithium iron phosphate anode materials, which is characterized in that acid and lithium iron phosphate are mixed to maintain pH value of 2-5, an iron source is added, then hydrogen peroxide and acid are added, and solid-liquid separation is carried out to obtain lithium leaching solution and iron phosphorus slag. Therefore, although the existing waste lithium iron phosphate battery recycling method is more, most of the existing waste lithium iron phosphate battery recycling method has the problems of complex flow, low lithium selectivity, high cost and the like, and is difficult to popularize and use in industry. Disclosure of Invention The invention aims to provide a low-cost, green and efficient lithium extraction method for a waste lithium iron phosphate anode material, which aims to solve the problems of low lithium leaching selectivity, complex process flow and high cost in the waste lithium iron phosphate anode material in the prior art. The method for extracting lithium from the waste lithium iron phosphate anode material in a low-cost green and efficient mode comprises the following steps of mixing waste lithium iron phosphate anode powder with water, adding an oxidant, stirring to obtain a leaching system, dropwise adding acid liquor to maintain the pH value of the leaching system within 2.6-4.5, simultaneously introducing oxidizing gas into the leaching system, and carrying out solid-liquid separation after leaching to obtain a lithium-rich leaching solution. The working principle and the beneficial effects of the scheme are that the scheme adopts a weak acidification-gas auxiliary oxidation mode to selectively extract lithium from the waste lithium iron phosphate anode material, the efficient selective leaching of lithium can be realized only by a small amount of acid and oxidant, the leaching rate of lithium can reach 99.5% at most, and the reagent cost is greatly reduced. In addition, the main material is basically not dissolved, the lithium-rich leaching solution is purer, and the lithium carbonate can be prepared without impurity removal