Plasma melting and useful application of molten slag

Research was conducted using a plasma ash melting furnace system (actual scale: 24-52 ton per day (t/d) to study the effects of melting incineration ash (removal of hazardous elements) as well as the effective use of slag deriving from the melting process. The system was run for over 28 months, during which tests on heavy metals indicated a Pb content of no more than 0.01 mg/L with no trace of dioxins, thus confirming the effective treatment of hazardous elements contained in the ash. As for the use of water-cooled, granular slag, a mixture of this slag and other materials (such as sand) was found to hold sufficient strength to be used as construction material and such. The flexural strength of interlocking blocks made from this slag mixture was found to be as high as 5.66 N/mm.(2) The handling of the slag during the manufacturing of the interlocking blocks was easy. A pretreatment process, by which ferrous-matter was removed from the incineration ash, was found to be effective for retaining a higher content of non-ferrous metals accumulating in the furnace (e.g. copper: 20-40%). (C) 1997 Elsevier Science Ltd.