Preparation of crude lithium carbonate from roasting-oxalic acid leach solution of clay-type lithium ores
At present,the lithium extraction by oxalic acid leaching of clay-type lithium ores has only studied the in-fluencing factors in the leaching stage,and lacks a systematic study on the subsequent lithium extraction from the leach solution.The leachate was treated through methods including light to precipitate iron,excess lime method,and calcium removal by the sodium carbonate to precipitate lithium.The effects of light time,calcium oxide dosage,sodium carbonate dosage,reaction temperature and reaction time on the precipitation separation of impurity ions were investigated.The experimental results indicate that under the conditions of 7 h of light exposure,2.5 h of re-action at 75 ℃ with 4 g of calcium oxide(per 30 mL of solution after light exposure),and 20 min of reaction at 75 ℃ with 40 mg of sodium carbonate(per 30 mL of solution after excess quicklime method),the precipitation rate of aluminum reaches 99.91％,while that of iron,magnesium,and calcium reaches 99.99％.Sodium carbonate cal-cium removal solution is concentrated and precipitated at high temperatures to obtain the lithium carbonate.Mecha-nistic analysis shows that iron is mainly precipitated as FeC2O4 after light exposure.The excess quicklime method makes aluminum and magnesium precipitate in the form of hydroxide,which effectively reduces the adsorption of lithium by amorphous aluminum hydroxide.Sodium carbonate,on the other hand,causes calcium to precipitate as the calcium carbonate and lithium to precipitate to give crude lithium carbonate.A method for preparing crude lithium carbonate from roasting-oxalic acid leach solution of clay-type lithium ores is obtained by experimental study.
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