Synthesis of mullite from sillimanite dissociation through transferred arc plasma torch

The transferred arc plasma process is characterized by extremely high temperatures, low environmental impact and short processing time. By virtue of high temperature and power density it paves the way for a high production rate. Hence an experiment was undertaken to synthesize mullite from the dissociation of sillimanite through thermal plasma processing. For this purpose, a transferred arc plasma (TAP) torch was specially designed on laboratory scale level and the operating parameters were optimized in order to achieve a maximum percentage of mullite with time and cost effectiveness. The phase and microstructure formation of the processed samples were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM) images. The obtained results clearly show that the torch input power and processing time strongly influence the mullite microstructure and phase formation. The present TAP torch processing gives maximum percentage of mullite (95%) through sillimanite dissociation at 15 kW power level with 4 min of processing time.

Research highlights
► TAP processing is a fast as well as energy conserving process to obtain mullite.
► Input power and processing time are the key parameters to obtain mullite grains.
► 15 kW power level and 4 min of processing time gives the maximum% of mullite.