Study On Applications And Phase Diagram Of Potassium Sulfate Prepared By Calcium Sulfate Method

This paper presents the investigation of applications and phase diagram of potassium sulfate prepared by calcium sulfate method in isopropanol-ammonia solvents. The influences of types of organic solvents on the yield of potassium oxide in the reaction of potassium sulfate preparation by calcium sulfate are studied, which indicates that isopropanol can be prefer selected as the additive. The phase diagram of the system K⁺, Ca²⁺//Cl^- , SO₄^2- in isopropanol-ammonia solvents at 25℃ is determined. Based on the phase diagram, the proper technology conditions of the production process are investigated by the single-factor and orthogonal experiments with the result of the reaction time of 60 min, reaction temperature of 20 ℃, isopropanol concentration of 7%, ammonia concentration of 28%, the solid/liquid ratio of 5.5/1.0, feed ratio of CaSO₄ and 2KC1 of 1.05:1.00mol/mol. The yield of potassium oxide under this condition is around 95% and the quality of the potassium sulfate can come up to the first rank standard of agricultural potassium sulfate. The new technology of potassium sulfate by potassium chloride and phosphoric gypsum with the existing condition of isopropanol-ammonia solvents is discussed. It is simple and of high yield of potassium oxide and superior quality of production. Isopropanol and ammonia can be reused by distillation in two sectors.