Preparation of Ceramsite from heavy metal contained municipal solid waste incineration fly ash synergistically with Silicon/Aluminum-containing waste

The harmless treatment and recycling of municipal solid waste incineration fly ash (MSWI FA) is a hot research concern in recent years. MSWI FA with high chlorine content, could be significantly reduced by washing treatment in water. MSWI FA after water de-chlorination is called water-washed fly ash (WFA). WFA is rich in calcium, up to 35 %-40 %, may be used to produce lightweight aggregate products by high-temperature sintering. However, silicon/aluminum content of the WFA is insufficient. Therefore, the silicon/aluminum-containing materials have to be blended. Construction waste – sand-washing mud (SM), which is rich in silicon and aluminum, and is also inherently non-toxic. The wastes were mixed and complementary to each other enabling synergistic co-disposal. The materials’ mass ratios were studied. Sintering temperature (850 °C, 950 °C, 1050 °C, 1150 °C), sintering time (30 min) on the physical and chemical properties of ceramic granules (CGs) were also investigated. The experimental results showed that under the optimized ratio (Ca: Si: Al=1.8:3:1), the best prevailing condition (calcined at 1150 °C for 30 min). The numerical tube pressure of CGs was 4.23 MPa, water absorption at one hour was 3.01 %, bulk density was 690kg/m³, and the leaching toxicity was significantly lower than the Chinese national standard (GB 5085.3–2007). It accorded with the high strength lightweight aggregate for building materials, the strength grade was 25 (GB/T 17,431.1–2010). This study provided a theoretical basis and practical experience for the harmless treatment and recycling of MSWI FA.