Development of a loose powder sintering method for the preparation of porous ceramic from municipal solid waste incineration fly ash.

Loose powder sintering was used to prepare porous ceramic from municipal solid waste incineration fly ash (MSWI FA) and waste glass (WG). Sintering experiments at various temperatures, holding times, AlO and SiC were conducted to investigate their effect on the ceramic properties and volatile heavy metal removal efficiency. The results show that increasing temperature from 1100 °C to 1250 °C promoted the transition of the mixtures from loose powder to a densified sintered matrix, with a bulk density increase of 31.10% and an open porosity decrease of 70.41%. The bulk density of the ceramic increased to 2.44 g/cm with 3% AlO addition. The removal rates of Pb, Zn, Cu and Cd were higher than 90% at 1200 °C for 90 min, and promoted by the increasing temperature and holding time. Notably, 3% AlO addition inhibited the volatilisation of Zn, Cu and Cd, particularly for Zn, the removal rate of which reduced to 61.66% at 1200 °C. The bulk density of the ceramic decreased to a minimum value of 1.48 g/cm with 4% SiC. The ratio of MSWI FA:WG:AlO:borax of 28.3:56.7:10:5 was proposed to obtain ceramic with a bulk density of 1.54 g/cm and a water absorption rate of 8.59% at 1150 °C. The leaching concentration of the porous ceramic met the Chinese regulatory standard (GB 8978-1996). Preparation of MSWI FA-based porous ceramics using the powder sintering method is a promising route for the harmless utilisation of MSWI FA. The porous ceramic is potentially applicable as a thermal-insulation building material.