Present Situation and Problems of Refractories for Waste Melting Furnace

Abstract
A current problem in the incineration of municipal, and industrial waste, is the occurance of environment hormones such as dioxin. In order to solve the problem, melting furnaces in which wastes are melted above about 1,300*C[Celsius degeree] have been developed.
The lining refractories of the furnace are severely attacked by CaO, Na2O, K2O, etc., which are included in waste slag. Cr2O3-containing refractory such as Al2O3-Cr2O3 system is the most often used because of its excellent resistance to corrosion. However, there is a problem that hexa-valent chromium, which is noxious to the human body, is easily formed by reaction between the refractory and the slag.
In this article, the reason why the Cr2O3-containg refractory has excellent corrosion resistance qualities, the conditions under which hexa-valent chromium formed, methods for suppressing generation of hexa-valent chromium and the possibility of refractory components excluding Cr2O3 for the furnace are described as a base of development of further excellent refractories.

Key words: melting furnace, Cr2O3-containing refractory, hexa-valent chromium