Reduction of iron ore with coal by microwave heating

Microwave heating of iron ore was investigated as an alternative to conventional reduction processes to solve the problem of slow heat transfer. Microwave heating and reduction tests were run on composite green balls made from coal and magnetite concentrate. Bench-scale tests were run on both powdered and pelletized feeds using a 15 kW microwave generator. A significant increase in the reduction rate was obtained. With 20% excess stoichiometric carbon in the mix, more than 90% reduction of the iron ore can be achieved in about 10 min at temperatures of around 1,000 degrees C. The reduction of iron ore with coal by microwave heating produces a pure, dust-free, high-Btu flue gas that can be used in related thermal operations. Depending on the parity, the reduced iron product could be fed directly to an electric arc furnace for melting. In some cases, the removal of a slag phase may be required to eliminate excess silica and alumina.