关键词: 铬酸钾, 甲醇, 乙醇, 溶解度, 溶析结晶, 清洁工艺

Abstract: 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.

Key words: potassium chromate, methanol, ethanol, solubility, solventing-out crystallization, clean process