Study On Preparation Of Alinite Clinker With Municipal Solid Waste Incineration Fly Ash

The market of municipal solid waste incineration(MSWI) fly ash is very large for widely using of municipal solid waste incineration technologies and then production of MSWI fly ash increasing year by year. MSWI fly ash has a high heavy metal leaching toxicity and contains persistent organic pollutants like dioxin,so how to realize non-hazardous treatment, quantitative reduction and resource recovery of MSWI fly ash become a hot research issue. Preparation of Alinite clinker with MSWI fly ash has been researched for its advantages of good solidifying effect to heavy metal and low energy consumption of clinker production.Preparation of pure Alinite and C11A7·Ca Cl2, micro-structures of Alinite,preparation of Alinite clinker with MSWI fly ash, appropriately sintering temperature and suitable additive amount of MSWI fly ash in raw meal, volatilization and solidification of heavy metals in the process of clinker calcining, heavy metals leaching in cement mortar have been studied, through chemical analysis, X-ray diffraction, petrography analysis, scanning electron microscopy, X-ray energy spectrum analysis, atomic absorption spectrum analysis and other analytic testing methods.Alinite mineral is loose and lacunaris continuous solid solution, which is blue-black etched by 1% nitric acid alcohol solution. With the rise of sintering temperature, the size of Alinite solid solution increase. Alinite begins to decomposition and C2 S formed when the burning temperature exceed 1350℃,and C3 S formed for C2 S absorbing f-Ca O. Decompostion and volatilization of Ca Cl2 affecting the formation of Alinite and C11A7·Ca Cl2, therefore amount of Ca Cl2 addition should be fully considered to reduce the impact to the formation of Alinite clinker.Study on the preparation of Alinite clinker, “4 modulus” methodology is suitable way for preparation of raw meal as it takes consideration of effect of Ca Cl2 decomposition on clinker burning. The optimum temperature for burning Alinite clinker prepared with MSWI fly ash is 1200 ℃. Adding MSWI fly ash in raw meal promotes formation of Alinite clinker, suitable addition amount of MSWI fly ash is5% to 15%. When the addition amount of MSWI fly ash exceed 15%, less Alinite mineral was formed, and the clinker strength greatly reduced.Between 800℃ to 950℃, volatile rate of heavy metals are higher; increasing the temperature, volatile rate of heavy metals become lower; volatile rate of heavy metalsreach the minimum for a great amount of Alinite mineral formed and heavy metals incorporated in clinker.With the increase of addition amount of MSWI fly ash,solidification rate of heavy metals decrease. The amounts of leaching heavy metals of Alinite cement mortar is small which meets the national standards.