Dissolution Behaviour of Chromium Substituted Haematites in an Oxidative/Reductive-Complexing Agent Environment

The dissolution behaviour of 3.5-12.5 at% Cr substituted haematites in a citric acid-EDTA-ascorbic acid (CEA) reductive-complexing formulation with and without alkaline permanganate (AP) oxidative pre-treatment is presented. In the direct treatment, with increasing Cr content of the oxide, employing CEA formulations containing increased concentrations of ascorbic acid could either completely or significantly solubilise the oxide. In the 3.5-10 at% Cr in the oxide, the concentrations of reducing agent employed in the CEA formulation to achieve a solubility of >40% in iron have been demarcated. The AP pre-treatment resulted in a release of only