Effect of SiO_2 Mixing Ratio on Solid Solubility of Heavy Metal in MSWI Fly Ashes in Ecological Cement

Cement solidifications test for fly ashes from MSW incinerator,which mixing SiO2 in different ratios,were carried out.Effects of SiO2 mixing ratios on heavy metals distribution and leaching toxicity in clinkers were studied.Experimental results indicate that increasing SiO2 mixing ratio would be beneficial to make more Cr,Ni,Cu and As stabilizing in clinker when mixing SiO2 below 16%.Whereas the solid solubility of Cr,Ni,Cu and As would decrease with the mixing ratio of SiO2 increases(above 16%).For Cd,Pb and Zn,the amounts of evaporation reduce with the mixing ratio of SiO2 increases.Adding SiO2 mixing ratio would validly restrain the evaporation quantity of Zn,but the volatilization amount of Hg would be immune from it.With the increase of mixing SiO2,the clinker samples become much compact in microstructure,and the leaching amounts of heavy metals decrease distinctly.