Processing of Refractory Ores in a Microwave Induced “Cold” Plasma

Abstract

ABSTRACTA Microwave Induced Plasma has been used to investigate the processing of metallurgically significant refractory oxides in a non-equilibrium or “cold” plasma. The main emphasis of this work has centered on the reduction of TiO2 in a hydrogen plasma. The plasma was maintained using microwave energy (2.45 GHz) in a single mode resonant cavity. The reaction was monitored for volatile species with a quadrupole mass spectrometer, while the extent of reaction was determined by an external standard X-Ray diffraction technique. The effect of process variables (absorbed power by the plasma, chamber pressure, and time) on the extent of reaction was investigated. Hydrogen reduction in a plasma has produced up to 60% conversion of TiO2 to Ti2O3 in 11 minutes with the sample on a grounded support rod, while only an 8% conversion is observed for a sample on an insulated support rod. Sample temperatures were below 735 K for most plasma conditions, based upon thermodynamic considerations.