In this article, history of MW heating and its general application are reviewed first. The MW heating started from 60 years ago, and their high temperature application was from about 80s. MW heating application can be classified with respect to the heating temperature. The applications were discussed in relation with their heating mechanisms, taking special account for the magnetic field contribution to the heating.
Researches on MW application to the iron and steel industry field have been conducted, recently. There are active research group members in ISIJ who have been performing both the fundamental and the application researches on the MW heating. Their works are briefly reviewed.
The authors' recent studies on the MW heating of Ti-containing Chinese blast furnace slags, and on the fundamental studies of MW carbo-thermal reduction of NiO for recycling metals from the pickling sludge are briefly presented.