Study Of Sintering Process From MSW Fly Ash And Sewage Sludge For Lightweight Aggregate

Municipal solid waste incineration (MSWI) fly ash was defined as a special hazardous waste world-widely, because of high leaching concentration of the heavy metals and high toxicity equivalent of dioxin-like compounds. Moreover, the mixed MSWI fly ash collected from semi-dry scrubber and fabric bag-house has a high content of chlorides, high ratio of CaO to SiO₂, and strong alkalinity, which increased the difficulty for its disposal. And swage sludge needs to be well treated too, because its containing of heavy metal and organic matter. Thermal treatment has the advantages of good treating effect and reducing the amount of fly ash and it becomes a tendency treating in the world. So, this paper is about the sintered process of the MSW fly ash and sewage sludge. The sintering treatment of fly ash and sludge were performed on orbicular specimens and at different operating conditions (include additive, sintering times, temperature, and component ratio). In order to determine the best sintering condition of which sintering process from MSW fly ash and sewage sludge were investigated the influence of various factors on characteristics of sintered product(compression strength, density fluctuations ratio, volume change ratio and ignition loss ratio). Results indicate that sintering product can be as lightweight aggregate reused for construction concrete under the best work condition (addition 1% borax, sintered time at 90min, sintering temperature at 1080℃, content ratio at 7:3.The process of sinter MSW fly ash and swage sludge can engender heavy metals migration. The migration characteristics of during sinter MSW fly ash and swage sludge was studied in the paper. The tube furnace was used in the experiment of sintering and the atomic-absorption spectrophotometer was used to determine the contents of heavy metals in the samples. This study investigated the migration characteristics of 5 heavy metals(Cd, Pb, Cu, Zn and Ni) in the sintering process of MSWI fly ash and swage sludge, and analyzed the influence of temperature and residence time onto the migration characteristics of heavy metals.