EVAPORATION FROM SYNTHETIC INCINERATOR ASHES MELTED BY PLASMA-ARC

Synthetic incinerator ashes of 40 mass %SiO2-40Ca0-20Al(2)O(3) (named Glass) and 36 mass %SiO2-36CaO-18Al(2)O(3)-10Fe(2)O(3) (named Fe-Glass ) were melted by argon plasma are, with iron rods used for are ignitio n. A direct current transferred type plasma generator was used with an output power of 6 kW. During are melting, the iron rod was melted and located in the centre of the molten ash. The temperature at the bound ary between the iron and ash melts was 2200 K and that at the edge of the ash 1870 K. X-Ray diffraction showed that the deposit vaporised fr om Glass was composed of Fe, FeSi and amorphous SiO2. The evaporation rates from Glass and Fe-Glass were 3.8 x 10(-4) g/s and 1.4 x 10(-4) g /s, respectively. It has been concluded that the rate of evaporation f rom the molten ash is affected by the vaporisation reaction which dete rmines the oxygen partial pressure in the whole system. (C) 1998 Elsev ier Science S.A.