Utilization of Glass Cutting Sludge and Sanitary Ware Sludge in Ceramic Pressed Bodies

Abstract

Ceramic manufacturers are finding the way to decrease firing temperature and recover their wastes in order to keep production costs down. In this study earthenware ceramic bodies were prepared by adding a soda-lime glass grinding effluent powder (dried sludge) as a fluxing agent at 0–50 wt.% into either sanitary ware sludge powder (from a sanitary ware manufacturing process) or fresh pottery clay from Ang-thong, Thailand. The dried and pressed mixtures were fired at 1100, 1125 and 1150 °C and tested for the firing shrinkage, modulus of rupture, water absorption and bulk density. The formed product microstructure was observed by the scanning electron microscopy, and the phase composition was characterized by X-ray diffractometer. The results revealed that the best condition for adding the glass powder in Ang-thong pottery clay was the inclusion of 10 wt.% soda-lime glass effluent powder in the pottery clay. Its flexural strength increased from 51.25 MPa to 93.40 MPa after firing at 1125 °C with the water absorption of 0.42 wt.% and the firing shrinkage of 10.25 %. The optimum firing temperature and soda-lime glass content in sanitary ware sludge were 1150 °C and 20 wt.%, respectively. Its flexural strength increased from 103.16 MPa to 118.16 MPa with the water absorption of 0.52 wt.% and the firing shrinkage of 13.67 %. The results illustrated the potential to use soda-lime glass cutting sludge and sanitary ware sludge as raw materials for earthenware ceramic body.