空气—双氧水联合氧化工艺选择性浸出废磷酸铁锂材料中的锂OA北大核心CSTPCD

Lithium in the spent lithium iron phosphate material(powder of cathode material from spent lithium iron phosphate battery)was selectively leached by combined oxidation with air and hydrogen peroxide,and then recovered in the form of lithium carbonate after lithium precipitation.The experimental results show that after air aeration for 300 min under the conditions of a liquid-solid ratio of 4 mL/g,a molar ratio of H2SO4 to Li of 0.5,a stirring speed of 250 r/min,and a reaction temperature of 50℃,and then reaction for 120 min with H2O2 dropwise addition(with a molar ratio of H2O2 to Li of 0.29)at the same reaction temperature and stirring speed,the leaching rate of lithium,iron and phosphorus is 93.47%,17.26%and 19.83%,respectively.This process can decrease the amount of hydrogen peroxide by more than 75%compared with the hydrogen peroxide oxidation process alone,significantly reducing recycling costs.Dissolved oxygen concentration has an important influence on the existence mode of Fe3+ in the leaching system:at higher concentrations(with air aeration),iron phosphate is dominant;at lower concentrations(without air aeration but in contact with air),iron hydroxide is dominant.