Intensified decomposition of vanadium slag via aeration in concentrated NaOH solution

A new metallurgical process via aeration for the decomposition of vanadium slag in concentrated NaOH solution was proposed. The improvement of oxygen mass transfer coefficient when using aeration at different NaOH concentration was studied and the effects of critical reaction parameters on vanadium extraction were systematically investigated. The optimal condition was determined to be: alkali concentration of 60%, reaction temperature of 130 degrees C, alkali-to-ore mass ratio of 6:1, stirring speed of 500 rpm. The yield of vanadium could reach to 97.41% after reacting for 6 h under this reaction condition. The reaction temperature in this new method is 50-270 degrees C lower than the current liquid oxidation methods reported in the literatures, and the medium alkaline concentration declined from 85% to 60%, exhibiting significant advantages in energy consumption as well as reactor design. Kinetics study indicated that the extraction of vanadium was governed by internal diffusion, and the apparent activation energy was calculated to be 17.57 kJ/mol. (C) 2017 Elsevier B.V. All rights reserved.