焼成法による溶融飛灰の無害化機構 [in Japanese] Detoxification Mechanism of Molten Fly Ash in Sintering Process [in Japanese]
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A Molten fly ash generated by direct melting process used in treating municipal solid waste (MSW) is designated as a specially-controlled waste in Japan due to the harmful heavy metals it contains. Proper detoxification before disposal in landfills is legally required, as in the case of fly ash produced by conventional MSW incinerators. As part of research and development of an incinerator fly ash treatment process using the sintering method, to date, the authors have clarified the removal mechanism of heavy metals such as lead (Pb) and cadmium (Cd), which are the main harmful heavy metals found in fly ash, and optimized the removal conditions based on thermodynamic and metallurgical approaches.<BR>Molten fly ash is more difficult to treat than incinerator fly ash. For research and development of a treatment process, a new pilot plant with a design capacity of 45kg/h was constructed in March 2004. Using this facility, we demonstrated that harmful heavy metals such as Pb in molten fly ash can be safely removed to trace levels which satisfy the Japanese environmental standard for soil, and the pellets obtained in the process can be recycled, for example, as artificial lightweight aggregate. And basic tests using the small-scale electric furnace were also carried out to collect data for elucidation of roasting mechanism. As the result, we confirmed that the influence of the hematite and lime concentration on pellet crush strength was very large and when the lime concentration was high, a lower hematite concentration was desirable.
Shigen-to-Sozai 123(1), 50-55, 2007-01-25
The Mining and Materials Processing Institute of Japan