A physicochemical model of yttrium behaviour in the weathering profile

Abstract

Introduction: The article presents original and literature data on the standard Gibbs free energy of 35 yttrium ions and complexes in an aqueous solution, as well as its three possible mineral phases. Methodology: The “Selector” program and a method of physicochemical computer modelling were used to analyse yttrium behaviour in the process of phyllitic schist weathering. Results and discussion: The content of Y in schists was similar to its average content in the earth's crust and was equal to 10-3 wt. %. It was established that in the weathering profile yttrium was stored as a solution of the Y(ОH)63- hydroxocomplex. YCO3+ and Y(CO3)2- carbonate ions prevailed in the reduction zone. Conclusions: Unlike most chemical elements, yttrium does not accumulate in bauxites but is removed from them, therefore its concentration ratio is 0.60.