Abstract
With the huge explored reserves of potash salts in Kazakhstan, there is still no production of potash fertilizers, the demand for which is constantly growing. In this regard, research of processing of the largest Chelkar deposit ore into potash fertilizers and salts is an urgent problem. The article presents the research results of washed potash ore decomposition with nitric acid and nitric acid suspension filtration. The filtering properties and granulometric composition of the insoluble residue were studied, on what basis the decomposition mode with precipitate double washing was determined. To ensure good suspension filterability, washed, uncalcined ore should be used. Tests of a by-product, gypsum, as a gypsum binder were carried out, which confirmed its compliance with the normally hardening gypsum binder of the G-2 B grade. Advantage of the obtained gypsum is its environmental friendliness. Salts, which are chlorine-free water-soluble potassium-magnesium fertilizers have been obtained by crystallization from nitric acid solution. On the basis of results of experimental-and-laboratory tests, a basic flow scheme has been developed for obtaining potash and complex potassium-nitrogen-magnesium fertilizers from the Chelkar deposit ore.