Mullite glass ceramics production from coal ash and alumina by high temperature plasma

The waste and highly hazardous coal ash from the power plants is proved to be a potential source for the production of low cost mullite glass ceramics when mixed with alumina at very high temperatures produced by plasma. In this present work, the coal ash and alumina are mixed at different weight percentages and treated with high temperature plasma produced by Transfer Arc Plasma Torch (TAP) of 10 kW power. The XRD patterns confirm that the complete single phase homogeneous mullitization occurs when 50% of coal ash is mixed with 50% of alumina. The SEM results also show that the formation of elongated needle - like mullite glass ceramics at very high temperatures. The TG – DTA analysis reveals that an endothermic phase transition and mullitization temperature occurs at 920°C when equal weight % alumina mixed with equal weight % of coal ash. The sharpened strong endothermic peak at 920°C reflects the homogeneity of formed mullite. The results show that the lowcost single phase mullite is obtained in a very short period of time (5 minutes) is found to be a key factor with required microstructure.