φ-pH diagram of V-Ti-H 2O system during pressure acid leaching of converter slag containing vanadium and titanium

Abstract

To analyze the thermodynamic characteristics of leaching process of converter slag, φ-pH diagram of V-Ti-H 2O system at oxygen partial pressure of 0.5 MPa, ionic mass concentration of 0.1 mol/kg and temperatures ranging from 60 to 200 °C was obtained by recently published critically assessed standard Gibbs energies and activity coefficients of various species. When pH<2, stable regions of V 3+, VO 2+ and VO 2 + exist in the stable region of TiO 2. The pH values of stable regions of vanadium and titanium decrease and redox potentials become more positive with the temperature increasing. Vanadium and titanium could be separated by one-step leaching based on thermodynamics. The experiment results of pressure acid leaching of converter slag show that leaching rates of vanadium and titanium are 96.87% and 8.76% respectively, at 140 °C of temperature, 0.5 MPa of oxygen partial pressure, 0.055-0.075mm of particle size, 15:1 of liquid to solid ratio, 120 min of leaching time, 500 r/min of stirring speed and 200 g/L of initial acid concentration. Vanadium and titanium could be selectively separated in the pressure acid leaching process, and the experiment result is in agreement with thermodynamic calculation result.