Optimization of Experimental Conditions in Single-Stage Process for Preparation of Potassium Sulphate from Magnesium Sulfate and Potassium Chloride

A method and a system for Single-Stage conversion of magnesium sulphate and potassium chloride to potassium sulphate in aqueous alcoholic solution at 50-85°C were developed. Raw magnesium chloride was a by-product formed in the process. The effects of reaction molar ratio, methanol volume, evaporation, and magnesium chloride content on the purity and the conversion rate of potassium sulphate were studied. The product and by-product were purified and the metal ions contents were determined by Atomic absorption spectroscopy. Results showed that the washing with methanol had a certain impact on the purity and the conversion rate of potassium sulphate. The potassium sulphate reached to the qualified standard, when the molar ratio of 2KCl and MgSO4 was 1:1. The recoveries of potassium sulphate (as final product) and potassium chloride (as raw material)in an aqueous alcoholic solution compound fertilizer were approximately 80% and 12.76%, respectively. Magnesium chloride had a significant influence on the purity and the conversion rate of potassium sulphate. Purities of products throughout can be controlled by using slight circuit adjustments and/or by additional water washes.