Reduction of iron ore with coal by microwave heating

Abstract

Microwave heating was investigated because it would largely solve the problem of slow heat transfer during reduction inherent in conventional reduction processes. Microwave heating and reduction tests were run on composite green balls made from coal and magnetite concentrate. Bench scale tests were run using a 15 KW microwave generator on both powdered and pelletized feeds. A significant increase in the reduction rate was obtained. Over 90% reduction of the iron ore can be achieved in about 10 minutes at temperatures about 1,000 C with 20% excess stoichiometric carbon in the mix. The reduction of iron ore with coal by microwave heating produces a pure, dust-free, and high Btu flue gas that can be used in related thermal operations. Depending upon the purity, the reduced iron product could be fed directly to electric arc furnaces for melting. Removal of a slag phase to remove excess silica and alumina may be required in some cases.