Study On Preparation Process Of Battery Grade Lithium Carbonate And Lithium Hydroxide

As the demand for lithium battery increases,the demand for lithium carbonate and lithium hydroxide as raw materials for synthesis of lithium battery materials increases sharply,and production enterprises have put forward innovative demands for their preparation methods.The microreactor has the characteristics of continuous operation and high efficiency of mass and heat transfer.Spray drying can realize efficient mass and heat transfer and simplify drying,crushing and other processes in production.In this paper,the preparation of lithium carbonate by microreactor and batch method and the preparation of lithium hydroxide by spray drying were studied.The main research contents are as follows:(1)Lithium carbonate was prepared by microreactor and batch method respectively by single factor experiment.The influences of lithium chloride concentration,molar ratio of sodium to lithium,reaction temperature and feed flow rate on the purity,yield,particle size and morphology of lithium carbonate were investigated.The experimental results show that the purity of the product decreases with the increase of the concentration of lithium chloride and the molar ratio of sodium lithium,and increases with the increase of temperature,and the feed flow has little effect on the purity.The yield increases with the increase of lithium chloride concentration,molar ratio of sodium to lithium and temperature,and has a weak correlation with feed flow.Among the influencing factors explored in the experiment,the concentration of lithium chloride has the greatest influence on the particle size and morphology of the products.At low concentration,lithium carbonate presents a flake agglomeration,while at high concentration,it presents a rod-like agglomeration.The optimum conditions for the preparation of lithium carbonate in a microreactor are: Ethanol was used as the solvent,lithium chloride concentration was 1 mol/L,molar ratio of sodium to lithium was 1.1,reaction temperature was 50℃,feed flow was 15 m L/min.Under these conditions,the purity of lithium carbonate was 99.81%,reaching the battery grade standard,the yield was 76.96%,and the average particle size was 21.92μm.The optimum conditions for the batch preparation of lithium carbonate are as follows: forward feeding,lithium chloride concentration of 1 mol/L,molar ratio of sodium to lithium of 1.1,reaction temperature of 50℃,feeding rate of2 m L/min.Under these conditions,the purity of lithium carbonate is 99.62%,reaching the battery grade standard,yield of 75.13%,average particle size of6.728 μm.(2)In spray drying experiment,single factor method was used to explore the influence of slurry concentration,feed flow rate and air inlet temperature on particle size,morphology and yield of lithium hydroxide products.The experimental results show that particle size increases with the increase of slurry concentration and feed flow rate,and decreases first and then increases with the increase of temperature.Among the three influencing factors,the slurry concentration has the greatest influence on the morphology of the product,and the product morphology is poor when the concentration is higher.The yield decreases with the increase of slurry concentration and feed flow,and increases first and then decreases with the increase of temperature.The optimal processing conditions were as follows: slurry concentration of 3.2wt.%,the inlet air temperature was 150℃,and the feed flow rate was 4m L/min.Under these conditions,the particle size distribution of lithium hydroxide was uniform,the average particle size was 3.03 μm,and the yield was 61.29%.The preparation of lithium hydroxide by spray drying is simple and has low energy consumption,which can effectively improve the production efficiency.The small particles of lithium hydroxide can be directly used in the cathode material industry of lithium batteries,and have certain industrial application value.