| The oxides of tungsten, iron, chromium are very strong carbide forming elements, therefore, it is a very useful method that their oxides are reduced by carbothermic In- Flight Plasma reduction. The experimental apparatus in the present study used a secondary nozzle and an electromagnet so that the plasma flame could rotate in the secondary nozzle. The variables of experiment were the amount and the sort of the reductants, size of feeding materials and the powder feeding rate. The reduced particles were collected in water cooled pipe and paper filter. By increasing the reductant ratio and the reduction ratio the fixed carbon content and free carbon content were increased. By increasing the powder feeding rate and the size of feeding material the reduction rates were decreased. The reduction rate of WO_(2.9) Fe₂O₃and Cr₂O₃were 80%, 90% and 20%, respectively, by the in-flight plasma process. The reduced particle size were below 0.03㎛ ; therefore, an ultra-fine powder could be obtained by the present in-flight plasma process. |
|
