天青石锶废渣氯化钡浸出及其动力学研究

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SrCl₂，制备过程复杂。实验以BaCl₂为浸出剂，浸出酸预处理后的天青石锶废渣中的SrSO₄，通过一步浸出得到SrCl₂。分别考察了浸出时间、浸出温度、BaCl₂/SrSO₄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℃，BaCl₂/SrSO₄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BaSO₄产物层扩散控制，其表观活化能为38.75 kJ/mol。Ba²⁺部分或全部取代SrSO₄中的锶，使得锶废渣中的锶以SrCl₂的形式被浸出。

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

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 SrCl₂ through a two-step method of carbonate conversion and hydrochloric acid leaching, and the preparation process is complicated. In the experiment, BaCl₂ was used as the leaching agent to extract SrSO₄ from the strontium lapis lazuli waste residue after acid pretreatment, and SrCl₂ was obtained by one-step leaching. The effects of leaching time, leaching temperature, BaCl₂/SrSO₄ 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 BaCl₂/SrSO₄ 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 BaSO₄ product layer, and its apparent activation energy is 38.75 kJ/mol. Ba²⁺ partially or completely replaces the strontium in SrSO₄, so that the strontium in the strontium waste residue is leached in the form of SrCl₂.