SOLUBILITY OF MAGNETITE IN HIGH-TEMPERATURE WATER AND AN APPROACH TO GENERALIZED SOLUBILITY COMPUTATIONS

Magnetite solubility in pure water was measured at 423 K in a fully teflon-covered autoclave system. A fairly good agreement was found to exist between the experimental data and calculation results obtained from the thermodynamical model, based on the assumption of Fe3O4 dissolution and Fe2O3 deposition reactions. A generalized thermodynamical approach to the solubility computations under complex conditions on the basis of minimization of the total system Gibbs free energy was proposed. The forms of the chemical equilibria were obtained for various systems initially defined and successfully justified by the subsequent computations. A [Fe3+](T)-[Fe2+](T) phase diagram was introduced as a tool for systematic understanding of the magnetite dissolution phenomena in pure water and under oxidizing and reducing conditions.