Study on the Roasting Mechanism of Vanadium–Chromium Slag with Sodium Hydroxide

It has been most widely used to extract vanadium and chromium by sodium roasting–water extraction. However, the current researches about this evolution law only stay at the macro-level. Therefore, it is especially important to study the mechanism of oxidation and sodium consumption in the process of sodium roasting. In this study, sodium hydroxide was used as a sodium additive for roasting experiments. The oxidation and sodiumation processes were systematically studied, providing a theoretical basis for industrial extraction of vanadium and chromium. The results show that the oxidation and sodiumation temperature range of V3+ and Cr3+ is from 425.8 to 882.8 °C. The roasting temperature of 800 °C is the optimum conditions. Under this condition, vanadium spinel is converted into NaVO3, while chromium spinel is converted into Na2CrO4 and CaCrO4.