首次测定了不同温度下铬酸钾在甲醇-水和乙醇-水混合溶剂中的饱和溶解度,结果表明,在同一温度下,铬酸钾的饱和溶解度随甲醇/水和乙醇/水质量比的增加而显著降低;对相同的甲醇/水或乙醇/水质量比,铬酸钾的饱和溶解度随温度的增加而增加. 提出了以乙醇作为溶析剂、采用溶析结晶法分离铬酸钾的新工艺,并对溶析结晶过程中各相关参数对结晶相分离效率的影响进行了理论分析和实验研究,表明了采用溶析结晶方法从水溶液中分离铬酸钾的可行性,为钾系亚熔盐法铬盐清洁工艺中铬酸钾的高效分离提供了新思路.
The solubilities of potassium chromate in the mixed solvents of methanol and pure water as well as ethanol and pure water were initially determined. The results show that the mass ratio of solvents to water (CH3OH to H2O and/or C2H5OH to H2O) has great influence on the solubility of potassium chromate in the mixed solvents. The solubility of potassium chromate in water decreases remarkably with the increase in the mass ratio of solvents at fixed temperatures, but increases slightly with the increase in temperature for fixed mass ratio of solvents. A new separation process for potassium chromate was proposed by solventing-out crystallization with ethanol as the solventing-out agent. The effects of different operation parameters related to the separation efficiency of the solventing-out crystallization process were theoretically analyzed and experimentally investigated. The results in this work confirmed the feasibility of applying the solventing-out crystallization method to the separation of potassium chromate from its aqueous solution, thereby providing a new approach to achieving the highly efficient separation of potassium chromate in the clean process for producing chromium compounds by the potash sub-molten salt (SMS) method.