The mechanism of structural and chemical transformations of tantalite, columbite, and zircon surfaces in the process of acid and electrochemical treatment of mineral suspensions

Abstract

The results of experimental studies and scientific substantiation of an effect of directional change in the chemical and phase composition of the surface and increase in the contrast of physicochemical and electrical properties of tantalite, columbite, and zircon in the course of treatment with anolyte (pH < 5) and a hydrochloric acid solution (HCl, pH 3–3.5) are reported. The mechanism of structural and chemical transformations of the mineral surface in the process of leaching with acid solutions are studied. This mechanism includes the activation of oxidation of iron atoms in the surface layer of tantalite and columbite with the transition from Fe(II) to Fe(III), destruction of the zircon surface with the formation of oxygen–vacancy defects of the SiO₃^2-- and SiO₂⁰-types, and intense dissolution of iron- and silicate-bearing films from the surface of rare-metal minerals.