Porous materials produced from incineration ash using thermal plasma technology

• Municipal solid waste incinerator (MSWI) ashes were treated and neutralized by thermal plasma technique.
• Water-quenched vitrified slag derived from melting MSWI ashes was applied to manufacture porous materials.
• Porous materials are lightweight and thermal insulators having considerable potential for building applications.

This study presents a novel thermal plasma melting technique for neutralizing and recycling municipal solid waste incinerator (MSWI) ash residues. MSWI ash residues were converted into water-quenched vitrified slag using plasma vitrification, which is environmentally benign. Slag is adopted as a raw material in producing porous materials for architectural and decorative applications, eliminating the problem of its disposal. Porous materials are produced using water-quenched vitrified slag with Portland cement and foaming agent. The true density, bulk density, porosity and water absorption ratio of the foamed specimens are studied here by varying the size of the slag particles, the water-to-solid ratio, and the ratio of the weights of the core materials, including the water-quenched vitrified slag and cement. The thermal conductivity and flexural strength of porous panels are also determined. The experimental results show the bulk density and the porosity of the porous materials are 0.9–1.2 g cm−3 and 50–60%, respectively, and the pore structure has a closed form. The thermal conductivity of the porous material is 0.1946 W m−1 K−1. Therefore, the slag composite materials are lightweight and thermal insulators having considerable potential for building applications.