Physico-chemical features of acid decomposition of dolomite

Abstract

The results of studies of the physico-chemical regularities of the acid decomposition of magnesium-containing raw materials are presented and the optimal technological mode of the individual stages of obtaining magnesium sulfate is determined. It has been established that the process of obtaining magnesium sulfate based on dolomite includes the following stages: decomposition of magnesium-containing raw materials with sulfuric acid; filtration of the resulting suspension with separation of calcium sulfate and insoluble residue and subsequent washing; crystallization and separation of magnesium sulfate; drying the target product. The main technological parameters that determine the stage of sulfuric acid decomposition are: the rate of sulfuric acid, the duration of decomposition, the method and procedure for introducing reagents, the content of magnesium sulfate in the liquid phase of the suspension. In this case, the concentration of sulfuric acid cannot be considered as the main technological parameter, since its numerical value is selected depending on the value of the final content of magnesium sulfate in the liquid phase, which in turn is determined by its solubility in water. It has been proven that the use of a flocculant at the decomposition stage provides an increased filtration rate, improved filtration performance, as well as keeping the filter cloth uncontaminated. The results of chemical and X-ray phase analyzes confirmed that magnesium sulfate obtained from domestic dolomite raw materials in its composition corresponds to magnesium sulfate obtained from foreign types of magnesium-containing raw materials - magnesite, brucite - and fully complies with the requirements of TU 2141016-32496445-00 “Magnesium sulfate”.