天青石锶废渣氯化钡浸出及其动力学研究

Study on the leaching and kinetics of strontium celestite residue with barium chloride

天青石生产碳酸锶后剩下的锶废渣,因含有大量的锶资源,属于一种二次资源。目前天青石锶废渣主要通过碳酸盐转化-盐酸浸出两步法来制备SrCl_(2),制备过程复杂。实验以BaCl_(2)为浸出剂,浸出酸预处理后的天青石锶废渣中的SrSO_(4),通过一步浸出得到SrCl_(2)。分别考察了浸出时间、浸出温度、BaCl_(2)/SrSO_(4)摩尔比、液固比对锶浸出率的影响。结果表明:浸出时间120 min,浸出温度90℃,BaCl_(2)/SrSO_(4)摩尔比2.0,初始液固比10 ml/g时的锶浸出率达到了68.79%。该浸出过程符合未反应核缩模型,且主要受BaSO_(4)产物层扩散控制,其表观活化能为38.75 kJ/mol。Ba^(2+)部分或全部取代SrSO_(4)中的锶,使得锶废渣中的锶以SrCl_(2)的形式被浸出。

The strontium waste residue left after the production of strontium carbonate from celestite is a secondary resource because it contains a large amount of strontium resources.At present,strontium celestite waste residue is mainly used to prepare SrCl_(2) through a two-step method of carbonate conversion and hydrochloric acid leaching,and the preparation process is complicated.In the experiment,BaCl_(2) was used as the leaching agent to extract SrSO_(4) from the strontium lapis lazuli waste residue after acid pretreatment,and SrCl_(2) was obtained by one-step leaching.The effects of leaching time,leaching temperature,BaCl_(2)/SrSO_(4) molar ratio,and liquid-solid ratio on the leaching rate of strontium were investigated respectively.The results showed that when the leaching time was 120 min,the leaching temperature was 90℃,the molar ratio of BaCl_(2)/SrSO_(4) was 2.0,and the initial liquid-to-solid ratio was 10 ml/g,the strontium leaching rate reached 68.79%.The leaching process conforms to the unreacted nuclear shrinkage model and is mainly controlled by the diffusion of the BaSO_(4) product layer,and its apparent activation energy is 38.75 kJ/mol.Ba^(2+)partially or completely replaces the strontium in SrSO_(4),so that the strontium in the strontium waste residue is leached in the form of SrCl_(2).