电石渣合成高纯碳酸钙的研究

采用氯化铵水溶液浸出电石渣中的钙,并对溶液进行净化,通入二氧化碳制备高纯的碳酸钙。考察了氯化铵水溶液浓度、过量程度和反应温度等对钙提取和净化的影响规律。在氯化铵溶液浓度为3%~27.11%(质量分数)和过量程度为0~25%时,杂质镁的去除率随氯化铵溶液浓度的增加而增加,随过量程度的增加而稍有增加,对钙的提取率影响不大。在15~70℃,浸出温度对钙的提取率影响不大,但镁的去除率随温度的升高略有下降。浸出和净化电石渣中钙的适宜工艺条件为:氯化铵溶液浓度为10%(质量分数),氯化铵过量10%,室温下反应60 m in。用浓氨水调节氯化钙溶液的pH至12.0,与二氧化碳反应制备碳酸钙的纯度为99.44%,白度为97.8%,杂质镁质量分数为0.015%,颗粒粒度为500 nm。

Studies on synthesis of high purity calcium carbonate with calcium carbide residue

Calcium in waste calcium carbide residue was extracted with aqueous NH4Cl solution,the obtained solution was purified simultaneously and high purity calcium carbonate was prepared by introducing CO2.Effects of aqueous NH4Cl solution concentration,excessive extent,and reaction temperature etc.on Ca extraction and purification were investigated.When aqueous NH4Cl solution concentration was at 3%~27.11% and NH4Cl excessive extent was at 0~25%,the removal rate of impurity Mg was increased with the increasing of aqueous NH4Cl solution concentration,and was slightly increased with increasing of excessive extent;and the extraction rate of Ca was hardly affected.At 15~70 ℃,the leaching temperature hardly improved the extraction rate of Ca,but Mg removal rate was slightly lowered with the temperature rising.Optimum operation conditions to extract and purify Ca were as follows:aqueous NH4Cl solution concentration was 10%(mass fraction),NH4Cl excessive extent 10%,room temperature,and reaction time was 60 min.Adjust pH of CaCl2 solution to 12.00 with aqueous ammonia solution,and react with CO2,the purity of the obtained CaCO3 was 99.44%,white content was 97.8%,impurity Mg content was 0.015%,and particle size was 500 nm.