Method and apparatus for melting iron and steel scrap

摘要

A method for melting iron and steel scrap wherein scrap is fed through a shaft furnace countercurrent to a reducing gas. The reducing gas is formed by passing air through a plasma generator and injecting coal and/or hydrocarbon into the hot air so that the ratio (CO2+H2O)/(CO2+H2O+CO+H2) of the resulting gas becomes less than 0.2. The energy needed for melting is supplied as sensible heat of the reducing gas. The energy for preheating the scrap is supplied by introducing oxygen containing gas into the preheating zone at a plurality of positions along the flow path of the reducing gas to provide stepwise combustion of the reducing gas. The introduction of the oxygen containing gas at said plurality of positions is balanced to keep the gas reducing to the metal scrap at scrap temperatures above 1000 DEG C., and preferably even above 800 DEG C. The invention also comprises an apparatus for carrying the method into effect, and the apparatus comprises means corresponding to the various method features above.