Studies on the kinetics of carbon tetrachloride chlorination of refractory metal oxides

Abstract

Studies on the kinetics of chlorination of the oxides of titanium, zirconium, niobium and tantalum by carbon tetrachloride gas in dilution with nitrogen, at low and moderate temperatures, have been carried out. In each case, the effect of time, temperature, partial pressure of carbon tetrachloride and the particle size, on the chlorination of the oxide, has been studied. The influence of some physico-chemical properties of the oxides and their halides on the kinetics process, has been discussed. The chlorination results below and above the dissociation temperature of carbon tetrachloride (∼773 K) have been examined to find out the difference in the kinetics by CC1₄ and those by elemental carbon and chlorine. From these kinetics results, the mechanism of the chlorination of each of the oxides, has been established and compared. The optimum experimental conditions for preparing the metal chlorides, keeping in view of the maximum utilisation of the carbon tetrachloride, have been established. The merits of carbon tetrachloride as a chlorinating agent, have been highlighted. From these kinetics results, the scope for chlorinating the refractory metal oxides, as well as their mixed oxides, at lower temperatures and lower partial pressures of carbon tetrachloride, with the scope for recycling the reagent, has been briefly discussed. Some preliminary results on the preferential chlorination of these oxides by carbon tetrachloride present in a typical tin slag, have been presented, to further substantiate the merits of carbon tetrachloride as a low temperature chlorinating agent.