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.