Study On The Process Conditions Of The Recovery Of Lithium And Iron From The Cathode Material Of LiFePO₄ Battery

In this dissertation,using cathode materials of spent lithium iron phosphate battery as raw material,inorganic acid as leaching agent,the valuable metallic elements were extracted and lithium carbonate was prepared using sodium carbonate as precipitator.And then the iron oxide yellow obtained in the precipitation of lithium carbonate was calcined to prepare iron oxide red.The main work and the obtained conclusions were as follows:(1)Using nitric acid and hydrochloric acid as leaching agent respectively,the leaching rate of lithium ion in the spent lithium iron phosphate cathode as the main index,the leaching conditions were investigated and optimized through single-factor experiments and orthogonal experiments.The characterization results of lithium carbonate samples obtained under the optimized condition showed:the water content were 0,169%,0.203%,the content of lithium carbonate were 97.46%and 97.44%,the particle size measurement of d10 of lithium carbonate were 3.289?m and 1.734?m,which met the requirements of industry standard of battery grade lithium carbonate.(2)Using the leaching solution by nitric acid under the optimized condition as raw material,sodium carbonate as precipitator,the recovery rate of lithium carbonate as the main index,the preparation and purification conditions of lithium carbonate were investigated and optimized.After purification,the average water content of the sample reduced from 0.169%to 0.167%,the average content of lithium carbonate of the sample increased from 97.46%to 98.66%with more uniform distribution in particle size.(3)The iron oxide yellow obtained in the precipitation of lithium carbonate was modified by sodium dodecyl benzene sulfonate(SDBS)and the modification conditions were investigated and optimized.The above iron oxide yellow was calcined to prepare iron oxide red and the calcination conditions were investigated and optimized.Under the optimized condition,the color of the as-prepared iron oxide red matched the pure sample,the sample particles size performed "normal distribution" in the scope of 1?100?m and the content of Fe2O3 reached 96.48%,which met the requirement of the national standard of iron oxide products(GBT24244-2009,>96%).