Abstract
To reutilize molten slag derived from an ash melting process, the lead volatilization mechanism under reducing conditions was investigated. Reducing conditions were established by introducing a CO-CO2-N2 gas mixture to the reactor or by adding graphite to the molten slag prior to the experiments. As samples, two types of simulated molten slag composed of CaO-SiO2-Al2O3 mixed with PbO were used and the lead volatilization behavior was studied at 1773 K. It was found that the lead volatilization rate increased on increasing the amount of reducing agent for both graphite and the CO-CO2 gas mixture. For the CO-CO2 reducing gas mixture, this increase was mainly attributed to PbO conversion to Pb. For the addition of graphite, the increase in lead volatilization ratio was considered to partially result from PbO conversion to Pb and partially from a reaction of graphite with SiO2 yielding volatile SiO. The volatile SiO gas was then emitted from the furnace, which brought about a reduction in the SiO2 content of the slag. As a result, the slag viscosity decreased, which led to an enhancement of the lead volatilization ratio.
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Nakada, H., Mihara, N., Kawaguchi, Y. et al. Volatilization behavior of lead from molten slag under conditions simulating municipal solid waste melting. J Mater Cycles Waste Manag 10, 19–23 (2008). https://doi.org/10.1007/s10163-007-0193-x
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DOI: https://doi.org/10.1007/s10163-007-0193-x