A Novel Process for Simultaneous Extraction of Iron, Vanadium, Manganese, Chromium, and Titanium from Vanadium Slag by Molten Salt Electrolysis

Disposal of slags from alloy steelmaking is a serious problem as the toxic metals in the slag such as chromium and vanadium can be leached out. Recovery of the valuable metals needs an effective, economically viable method with a minimum number of unit processes. In the present work, a novel process for simultaneous recovery of iron, vanadium, titanium, chromium, and manganese from vanadium slag is proposed including the chlorination of vanadium slag in molten salt and electrolysis of the salt bath. The optimal conditions for the chlorination are an AlCl3-slag mass ratio of 1.5:1 and a salt bath composition (NaCl-KCl)-AlCl3 mass ratio of 1.66:1, at 900 degrees C for 8 h. The chlorination ratio of iron, vanadium, chromium, and manganese can reach 90.3%, 76.5%, 81.9%, and 97.3%, respectively, and the titanium volatilization ratio was 79.9%. Metal chlorides in molten salts are electrolyzed at 900 degrees C with graphite electrodes. Valuable metals (Fe, V, Cr, Mn) were deposited on the cathode in terms of alloy or metal of granular shape. The possible mechanisms involved in these findings were explored. The main compositions of residue are Al2O3 and SiO2, which has the potential usage for landfilling and or building by mixing with other substances for instance.