An electrochemical study of the reduction and dissolution of ilmenite in sulfuric acid solutions

Electrochemical techniques have been used to investigate the reduction and dissolution of two different ilmenite samples in 450 g L− 1 sulfuric acid solutions at elevated temperatures. The results have shown that the dissolution rate of ilmenite (FeTiO3) is low at potentials above about 0.3 V at which potentials the dissolution of ilmenite and the reduction of hematite (if present in the ilmenite sample) are the main reactions. At more negative potentials the dissolution of ilmenite increases simultaneously with reduction of ilmenite to trivalent titanium. These observations are consistent with those predicted from thermodynamic data. Hematite has a higher dissolution rate under reductive conditions than ilmenite. Studies of the effect of temperature on the dissolution of ilmenite at low potentials such as 0 V have shown that in the temperature range of 65–95 °C, the activation energy is about 50 kJ mol− 1 and this together with the high ratio of the charge passed to metals dissolved suggests that the rate of the non-reductive dissolution reaction is not significant under these conditions.