毒重石尾矿钡渣制取高纯氯化钡的研究

通过改进的两次盐酸浸取法将毒重石尾矿钡渣中的钡转化为氯化钡实现二次回收，考察了包括液固比、盐酸浓度、浸取时间、浸取温度等因素对除杂提钡效果的影响。实验结果表明，第一步盐酸洗渣能将铁、钙、锶等杂质酸化为相应的氯盐，并将其大部分转入液相，所得含钡滤渣进行第二步盐酸浸取，得氯化钡溶液。实验优化工艺条件：第一步盐酸洗渣，液固质量比为1∶2，盐酸浓度为1 mol/L；第二步盐酸浸取，液固质量比为7∶1，盐酸浓度为2 mol/L，浸取时间为2 h，浸取温度为70 ℃，钡的回收率可达95%；第三步氯化钡粗品精制，用草酸进一步沉淀钙、锶，调节滤液pH为3，滤液蒸发浓缩结晶，晶体经无水乙醇洗涤后烘干，所得氯化钡产品纯度可达99.9%。

Research on preparation of high pure barium chloride from barium dregs of witherite tailings

The recovery of barium from the barium dregs of witherite tailings was studied by using an improved two-step HCl leaching method.The effects of several factors，including liquid-solid ratio，concentration of HCl，leaching time，and leaching temperature etc. on the leaching and purification of barium were investigated.The results showed that the first HCl leaching step could convert the impurities of iron，calcium，and strontium etc. into their chlorides respectively，and could dissolve most of them in the water phase；the second one could convert the residue barium of last step into liquid barium chloride.The optimal conditions were as follow：liquid-solid ratio was 1∶2 and HCl concentration was 1 mol/L in the first step； while 7∶1 of liquid-solid ratio，2 mol/L of HCl concentration，2 h of leaching time，and 70 ℃ of leaching temperature in the second step.The recovery of barium reached 95% under those conditions.By adding oxalic acid，the Ca²⁺ and Sr²⁺ could be removed by precipitation in the third step，at the pH of 3，BaCl₂ crystal was separated by evaporating concentration.The barium chloride with the purity of 99.9% was prepared after ethyl alcohol washing and drying.