Arc-plasma reduction of vanadium oxide with carbon

The reduction of vanadium pentoxide by carbon has been investigated in an argon plasma-arc furnace. Briquettes of vanadium pentoxide and carbon mixtures have been examined and the results are as follows: 1) The optimum mixing ratio of carbon and vanadium pentoxide, C/V2O5, is approximately 4.5 and is smaller than the stoichiometric ratio of 5. When the mixing ratio is less than 4.5, the oxygen remaining in the product increases, while the vanadium carbide content increases when the ratio is greater than 5. 2) The sample is fused within 45 seconds by the plasma-arc and the reduction of vanadium oxide proceeds rapidly to nearly 90% vanadium content in the melt. Subsequent reduction in the molten state is slow. Within 10 minutes the vanadium content reaches a maximum of 96%. 3) Preliminary sintering of the briquette results in good recovery of vanadium due to the diminished loss of the sample under the plasma flame. 4) An increase of the vanadium content is not observed as temperature is increased from 2100 to 28000C. 5) The hardness of the product with the highest vanadium content is about H sub( v) 290 and is much larger than that of vanadium metal due to the small amount of remaining oxygen and/or carbon. 6) By means of EPMA, it is observed that the well developed, dendritic, primary crystals contain a small amount of carbon and oxygen in solid solution is observed. In this study, a vanadium metal of 96% purity has been produced within 10 minutes in spite of the strong affinity of vanadium for carbon or oxygen. (author)