| Lithium is the lightest metal and the most active alkali metal element in the world.Its atomic number is 3,atomic weight is 6.941,silver white,density is 0.534 g/cm3.It has unique physical and chemical properties such as high specific heat,conductivity and strong chemical activity.It has been widely used.In nature,spodumene,lepidolite,bauxite,seawater and underground brine are the main minerals.Lithium is widely used in battery industry,aluminium industry,lubricant,ceramics industry,refrigerant,nuclear industry,glass industry and optoelectronic industry.Its application in traditional industry continues to grow,and its application in civil industry,high-tech and military industry continues to expand rapidly.Lithium carbonate is not only a key product for the production of metallic lithium and secondary lithium salts,but also an indispensable raw material in some fields such as batteries,glass,ceramics,lubricants,energy,medicine,and petrochemicals.In recent years,with the development of low-carbon economy and clean energy industry,especially the lithium battery industry,the demand for Li2CO3 is increasing.In this paper,the extraction of lithium from the underground brine of Jiangling was used as raw material.The variation of lithium ion concentration in the process of evaporation and concentration of underground brine in Jiangling,Hubei Province was studied.The process of extracting lithium in high concentration sodium chloride solution and the process parameters of lithium carbonate crystallization process were studied.The additives were also studied.The influence of factors on the purity,crystal form,etc.during the crystallization of lithium carbonate.(1)The study of the salt precipitation law and the change of lithium ion concentration in the underground brine concentration process showed that:when the initial concentration of NaCl was 269.35 g/L,the concentration of NaCl first increased then decreased with the increasing of evaporation rate.And the concentration of KC1 increased as the evaporation rate increased.When the evaporation rate was 34.80%,NaCl started precipitating;KCl started precipitating when the evaporation rate was 66.10%.The concentration of Li-increased as the evaporation rate increased.Determined the potassium precipitation point and the content of each ion in the mother liquor.Through the study of the salt-dissolving potassium law,the change rate of lithium element and the change of lithium ion concentration during the evaporation and concentration crystallization process were determined.Basic data was provided for the extraction of lithium from underground brines.(2)This paper mainly studied on the crystallization problem of lithium-containing brine in the process of preparing high-purity lithium carbonate by reaction with sodium carbonate.By investigated the effects of initial reaction crystallization concentration,reaction temperature,feed rate,seed dosage,stirring rate,feed concentration and additived on the average particle size and crystal morphology of lithium carbonate products,the preparation of lithium carbonate by reaction crystallization was optimized.Process parameters.The research shows that under the action of different optimization conditions and additives,the morphology,particle size and solid-liquid separation effect of lithium carbonate crystal can be changed by regulating the reaction crystallization process of lithium carbonate.The purity of the crude lithium carbonate obtained under such parameters was 94.86%.(3)Purification of the extracted crude lithium carbonate by carbonization decomposition method,The experiment mainly studied on the process of purifying Li2CO3 by carbonization decomposition method,and the carbonization temperature and solid-liquid ratio respectively(refers to the mass of solid Li2CO3 and deionized water the effect of factors such as volume ratio,unit g/mL),the same as below,carbonization time on the purity and recovery of Li2CO3,the optimum process conditions were:carbonization temperature of 28? solid-liquid ratio of 1/40,carbonization time For 2.0 h,the carbonization stirring rate is 30 r/min.Under this condition,the purity of Li2CO3 purified by the purification is about 99.45%,and the recovery rate is about 70.0%,which meets the requirements of battery-grade lithium carbonate. |
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