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⁻¹, 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.

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