Refractory lining for melting furnaces

Until the 1970s, the cold blast cupola furnace was the traditional method of melting cast iron. It was a polluting, energy-inefficient process that consumed large quantities of refractory materials (over 30 kg/ton of cast iron). Developed after the Second World War, the hot-wind cupola furnace increased hourly output and allowed operation in campaigns lasting several successive days. The 1973 oil crisis forced smelters to reconsider their melting and holding equipment, particularly for cast-iron production. From then on, energy had to be saved.

In foundries, this necessary modernization only became apparent from 1975 onwards. Until the 1990s, equipment using electricity and natural gas was gradually developed, notably electric induction furnaces and gas rotary furnaces.

The emergence of these new melting processes and their technical nature have forced refractory manufacturers to develop new processing concepts and adapt materials to these new applications, which are more demanding in terms of thermal performance, specific consumption and service life.

This article describes these new techniques for producing, operating and maintaining refractory linings for both electric crucible induction furnaces and rotary gas furnaces. The choice of these linings in relation to the melting bed and the metallurgy are also discussed in detail.