STUDY OF THE CHEMICAL PROCESS OF FIXING SALT WASTE IN THE MINING COMPLEX OF THE DEHKANABAD POTASH FERTILIZER PLANT

Abstract

A detailed study of the essence, features and practical possibilities of existing modes and methods for fixing salt
waste that differ in chemical composition, physical and mechanical as well as geotechnological characteristics
has established, that the most suitable method for fixing salt waste from the Tyubegatan potash deposit is a
chemical method – the method of silicatization by a single solution method with additives of hardeners similar
in nature and origin to the processed salt waste substances. Based on the analytical, computational and experimental
studies of the processes of fixing salt waste, a sodium silicate solution with initial data ρ=1.45 – 1.50 g/cm3, a
silicate module of 3.0 – 3.5 and hardeners – bentonite and low grade phosphorite (P2O5 < 9,0 %) of fine grinding was selected as a fixative. The optimal parameters of the proposed fixing mixtures are: sodium silicate solution ρ=1.2 g/cm3, η=3 – 5 MPa·s, silicate modulus 2.5 – 2.8, temperature from 5 to 30 оC. Content of additives selected in the first recipe of 1.0 – 1.2 % bentonite, and the second from 2 to 5 % of low-grade phosphate (P2O5 ≤ 9 %).
On the base of mathematical expressions and given geotechnical and physical and chemical characteristics of the fixed layer of the salt waste, we have determined volumes and the solution flow rate-fixer for fixing 1 m3 of sand. We estimated the speed, the scheme of 1 + 3 → 2 +4 injection of the fixing solution: four-point-paired, diagonal-sequential. Based on the results of theoretical, laboratory and pilot studies of the process of salt waste fixing, we developed the method, the recipe, the project and the action plan for checking the quality of work and safety of implementing a chemical method for fixing salt waste of the Tyubegatan potash deposit.