高钙锶比卤水体系中分离提取氯化锶的相化学与热力学研究

Oil-field water, gas-field water and other brine mineral resources in Qinghai Nanyi Mountain are rich in potassium, boron, lithium, strontium, bromine, iodine and other high value-added elements. Brine included strontium is rich in resources, but also has the advantages of simple processing technology, so the development prospect is very considerable. The oil-field brine contains a lot of calcium chloride, strontium products difficult to isolate, unable to obtain high purity strontium products. In order to solve the problem of separation of high calcium strontium ratio of strontium chloride oilfield brines, this study intends to add potassium chloride in the ternary system CaCl2−SrCl2−H2O, potassium chloride and calcium chloride can form double salt, strontium chloride and potassium chloride cannot form double salt, and the double salt break down easily, potassium chloride is easy recycling and reusing, adding potassium chloride to progressively reduce the ratio of calcium and strontium, in order to achieve separation and extraction strontium chloride from high calcium and strontium ratio brines.

青海南翼山油田水、气田水等卤水矿产资源富含钾、硼、锂、锶、溴、碘等高附加值元素。卤水锶矿不仅资源丰富，而且加工工艺简单，因此开发前景十分可观。但是油田卤水中含有大量的氯化钙，钙锶比极高，锶产品很难分离，无法获得高纯锶产品。为了解决高钙锶比油田卤水中氯化锶的分离难题，本项目拟通过在CaCl2-SrCl2-H2O体系中引入氯化钾，利用氯化钾与氯化钙形成复盐而不与氯化锶形成复盐特点，并且钾钙复盐能够分解分离，这样氯化钾可以再回收、重复使用，从而实现加入氯化钾来多级逐次降低钙锶比，进而达到分离提取氯化锶的目的。

本项目针对高钙锶比油田水中提取氯化锶分离困难的问题开展基础研究，通过对钙锶氯化物相关体系的水活度、溶解度等热力学性质进行实验测定和相平衡热力学模拟，从相图基础及固液相转化规律的角度提出了高钙锶比卤水分离提取氯化锶的有效方法和途径，为高钙锶比卤水体系提取氯化锶的工艺设计提供了技术支撑。取得的主要研究结果为：（1）建立了钙锶共存氯化物体系重量分析方法。（2）获得了钙锶氯化物相关体系323.15 K时的水活度和溶解度等热力学数据。（3）构建了包含固溶体的钙锶氯化物体系相平衡热力学模型。（4）提出了高钙锶比卤水体系分离提取氯化锶的有效方法和途径。