The use of Al 2 O 3 as heat-sink during vanadium extraction by thermite process

Abstract

Vanadium is prepared by aluminothermic reduction of oxides. As the reaction with V₂O₅ is highly vigorous, the reduction is carried out with V₂O₅/V₂O₃ mixture for controlled reaction. Reduction of V₂O₅ alone to vanadium with the addition of Al₂O₃ as heat-sink is proposed in this work. While keeping the heat of process constant at 3680 kJ/kg in laboratory thermite reactors, the slag fluidiser CaO was partially and then fully replaced with Al₂O₃. Use of Al₂O₃ resulted in controlled reaction (with recovery as metal reaching from 50% to 83%), lesser loss in slag (from 10% to 1% vanadium) and lower nitrogen (from 1000 ppm to 130 pm) in metal. MgO of the reactor sometimes participates in the reaction. The loss of vanadium in slag is related to MgAl₂O₄ content of the slag. Molten Al₂O3 appears to scavenge the dissolved nitrogen from molten vanadium. Results have been explained from available thermodynamic data.