Study On The Reactive Crystallization Of Lithium Carbonate

A wide range of lithium carbonate are indispensable materials which can be used in glass,energy,metallurgy,batteries,medicine and other important industrial fields.Because of the global rise and development of new energy,momentum and energy storage with lithium ion batteries,as a core raw material of lithium carbonate,its market prospect is very broad.The average particle size of current industrial lithium carbonate is too small,distribution is uneven,morphology of crystal products is acicular.With the high moisture content and high content of impurities it is difficult to filter recovery and it lead to subsequent large energy consumption of drying and low purity.The key to solve the above problem is to improve the product particle size and morphology.Based on the problem of production process,in this paper,the reaction process of lithium carbonate crystallization was systematic studied.In this work,the solid-liquid phase equilibria of Li+,Na+/Cl+,CO32--H2O quaternary system at 363.15 K was studied experimentally via the classical isothermal solubility equilibrium method.According to Li+,Na+/Cl-,CO32--H2O quaternary system study,the phase diagram was plotted and it contents four single solid phase crystallization area,two invariant points and five univariant curves.Due to the solubility of lithium carbonate is low,it occupies the largest solid field,it is easy to precipitate crystal,it has guiding effect to the follow-up process optimization.A novel size and morphology controlling technology of Lithium carbonate in Reactive crystallization process were proposed.The effects of reactive crystallization temperature,rate of feed of sodium carbonate,seeding and stirring rate on the particle size and the effect of additive on the morphology were studied.By study of orthogonal experiments,the optimal experimental conditions for the reactive crystallization of lithium carbonate were concluded by:the sodium carbonate feeding rate was 0.5 ml·min-1,seeding was 2%,stirring rate was 400 r·min-1,reactive temperature was 353.15 K and additive was 2%sodium hexametaphosphate.The average size of particles is 132 ?m with the coefficient of variation of 51.53%.As a result,a optimized crystallization technology which products lithium carbonate crystal with uniform size and preferred morphology was proposed.In continuous operation the orthogonal L9(34)experiment was designed to examine the influence of four factors like reaction temperature,concentration of reactants,residence time and stirring speed on the product particle size.The optimal process parameters are:temperature was 363.15 K,the residence time was 200 min,sodium carbonate mass fraction was 22.0%,stirring speed was 600 r·min-1.With adding 2%sodium hexametaphosphate good spherical lithium carbonate products were gotten,the particle size of lithium carbonate products were greatly improved(the product whose average particle size is larger than 220 microns accounted for 67%),the purity was 99.12%,moisture content reduced to 0.82%.