Research of the process of obtaining potassium fertilizers from carnallite ore

Abstract

To provide domestic and foreign markets with potash fertilizers Kazakhstan has begun to create own production of these products. But at the moment enterprises engaged in mining potash salts did not reach a practical stage. The Chelkarcarnallite ore deposit is a unique one in solving these urgent problems. The article presents results of the study of processing Chelkar potash ore washed from sodium chloride to obtain a potassium fertilizer containing potassium and magnesium sulfates. The kinetics of nitric acid decomposition of carnallite ore has been investigated. The calculated value of reaction activation energy of potassium sulfate and nitric acid interaction characterizes the kinetic region of the process behavior. Optimal conditions for decomposition of washed calcined ore with 30 % nitric acid solution at 50 °C were determined. It has been found that to ensure better filtration properties and high rate of suspension separation, washed non-calcined ore should be used to exclude gypsum dehydration, which causes its phase conversion into anhydrite. The double salt of potassium-magnesium sulfate was separated by crystallization from nitric acid extract and an ammoniated mother liquor drying allowed to obtain a salt, which is ballast-free chlorine-free complex nitrogen-potassium-magnesium fertilizer.