Nucleation and growth kinetics of spinel crystals in vanadium slag

Abstract

During its converter extraction process, vanadium is oxidised into vanadium slag and forms spinel crystals. The spinel crystallisation process is one of the most decisive factors in the subsequent extraction and hence is worth exploration and discussion. The classical crystallisation kinetic model presented by Turnbull and Uhlmann was employed to analyse the crystallisation processes of vanadium, chromium and titanium spinel crystals in the vanadium slag. The crystallisation abilities of the three kinds of spinels were quantified and found to follow the order FeCr₂O₄>FeV₂O₄>Fe₂TiO₄. Furthermore, the precipitation sequence of spinels in the vanadium slag during cooling was achieved as FeCr₂O₄→FeV₂O₄→Fe₂TiO₄, and a suitable heat treatment condition on the vanadium slag was proposed. Finally, the optimum temperature range that benefits the precipitation of spinels was obtained as 1507–1557 K by both theoretical calculation and experiment.