Volatilization Behaviors of Lead from CaO-SiO2-Al2O3 Molten Slag in an N2-H2S Atmosphere

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The rate of volatilization of a lead compound from CaO-SiO2-Al2O3 molten slag was measured in an N2-H2S atmosphere at temperatures of 1673-1773K. The composition of the slag sample was adjusted to CaO 20-30wt%, SiO2 30-60wt% and Al2O3 20-40wt% with an initial PbO content of 2000mg · kg<SUP>−1</SUP>, which simulated molten slag from the gasification-melting of MSW. The rate of volatilization of lead from the molten slag was determined by the time-change of the content of PbO remaining in the slag.Results showed that the PbO in CaO-SiO2-Al2O3 molten slag volatilized as PbS in the N2-H2S atmosphere and the rate of volatilization of PbS was higher than that of volatilization of PbO in an N2-O2 atmosphere. The apparent rate constant of volatilization of PbS increased with an increase in H2S partial pressure and was higher for molten slag with high-CaO content and low viscosity. Moreover, at the same partial pressure of H2S and HCl, the apparent rate constants of volatilization of PbS and PbCl2 from molten slag were nearly equal and increased with rises in temperature.