Modeling the Kinetics of Saline Minerals Dissolution in Dombrovsky Quarry at the Kalush-Golinsky Potassium Salts Deposit

Abstract

The article deals with the peculiarities of the chemical composition formation of brines in the Dombrovsky quarry, primarily due to the dissolution of potash ore minerals and host rocks in water coming from the pebble horizon and atmospheric precipitation. The solubility of the ore body minerals has been studied, and it ranges from 333 to 502 g∙dm–3. The boundary conditions for the formation of a saturated salt solution were determined. The estimated concentration of saturated potash ore solution under normal conditions is 426 g∙dm–3. The mechanism of dissolution is considered from the standpoint of D.I. Mendeleev's chemical theory of solutions. The temporary dynamics of minerals dissolution of the ore body is studied experimentally. The parameters of kinetic-diffusion process are calculated. The rate of the dissolution process, which occurs in the kinetic region, significantly exceeds the rate of concentration diffusion of hydrated ions: from 5 to 400 times depending on the mineral composition of salts. Theoretically from the point of view of multistage process kinetics and experimentally in laboratory conditions it is proved that the process that determines the formation of the chemical composition of brines (the slowest stage) is the concentration diffusion of hydrated ions Na+, K+, Cl–. They enter the liquid phase due to the minerals dissolution of the ore body and host rocks of soil and sides of the quarry, in the direction of overcoming the concentration difference - from the lower layers of the brine to its surface. This conclusion is confirmed by the ratio of weight coefficients а1 and а2. The contribution of the process of the main minerals dissolution of the ore body to the chemical composition formation of the solution is significantly less than the concentration diffusion process.