Preparation of glass-ceramics using gasification residue of sewage sludge

Glass-ceramic was successfully prepared by mixing limestone, dolomite, Cr2O3 and TiO2 with gasification residue of sewage sludge. The parent glass melted at 1450 degrees C for 2 h can be bulk crystallized by two-step heat-treatment, i.e., nucleation at 750 degrees C for I h and crystallization at 1000 degrees C for 1.5 h. The main crystal phase of the glass-ceramics consists of augite as determined by XRD and presents interlocking structure of prismatic crystals under ESEM. Results of leaching experiments (TCLP test) show that heavy metals from the sewage sludge were solidified in the glass-ceramics. Therefore the proposed approach of sewage sludge residue recycling proves to be economically and environmentally viable.