Agglomeration phenomenon and regulation method of lithium carbonate crystal
Reaction crystallization using lithium chloride and sodium carbonate as raw materials is the main method for preparing lithium carbonate.To improve the yield of lithium carbonate,reduce its sodium content and obtain a narrow particle size distribution,a single-factor method was used to obtain a range of optimal experimental conditions.The experimental results showed that when the reaction crystallization temperature was 80℃,the stirrer speed was 600r/min,the lithium chloride concentration was 3.20mol/L,the positive feeding method was used,the seed crystal addition amount was 2.00g/L,the seed crystal particle size was controlled to be less than 54μm and the ultrasonic power was 100W,the obtained lithium carbonate had high yield,low Na content and narrow particle size distribution.In order to further optimize the experimental conditions to improve the lithium carbonate yield and reduce the sodium content in lithium carbonate,the Design Expert 13.0 software was used to select the reaction temperature,seed addition amount and ultrasonic power for a 3-factor 3-level by response surface analysis.The fitted yield equation was with a fitted correlation coefficient R2=0.9784.The fitted equation for the sodium content in lithium carbonate was with a correlation coefficient R2=0.9588.The correlation between the predicted value and the measured value was good.The conditions obtained after optimization could be verified to obtain a lithium carbonate yield of greater than 85%with sodium content controlled below 0.30mg/g Li2CO3.The lithium carbonate crystal agglomeration within the experimental particle size range was in agreement with the Thompson model,which could provide assistance for the design of the crystallizer.The experimental conditions obtained through research could provide a basis for adjusting process parameters for lithium carbonate production and guidance for improving product quality.
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