Co-disposal of municipal solid waste incineration fly ash and bottom slag: A novel method of low temperature melting treatment

Conventional melting for disposing municipal solid waste incineration (MSWI) fly ash or bottom slag needed high temperature and consumed high energy. High calcium content in fly ash and high silicon content in bottom slag brought them high melting point, respectively. Based on the analysis of chemical composition and phase diagram, suitable contents, namely 30%-40% CaO, 45%-60% SiO2 and 10%-15% Al2O3, were proposed to obtain a lower-melting-point mixture system. When the mass ratio of fly ash to bottom slag was 1:5, lowest melting point can be obtained. It was 1,190 degrees C, lower than that of fly ash (1,448 degrees C) and bottom slag (1,310 degrees C). The toxicity characteristic leaching procedure of slags obtained from low melting treatment met the leaching toxicity of Chinese standard GB 5085.3-2007, and the slags containing about 25 wt% CaO, 10 wt% Al2O3 and 45 wt% SiO2 can be used for preparing CaO-Al2O3-SiO2 glass ceramics. The co-process of fly ash and bottom slag realized the low temperature melting treatment with low energy consumption.