Continuous steel mfr. from iron ore - using brown coal to reduce the ore to sponge iron

摘要

Steel is continuously made by (a) direct redn. of iron ore with a solid redn. agent, pref. brown coal, in a rotary drum furnace (1) to obtain sponge iron; (b) Scrap and possibly the sponge iron are melted down in a shaft furnace (2); (c) Molten steel from (2) is fed into an electric furnace (3) to make steel with the required compsn. possibly by adding the sponge iron; (d) The exhaust gases from (1) are fed into (2) above the molten sump, for heating scrap and sponge iron. The exhaust gases from (1) are pref. fed via hot gas ducts to (2), possibly after removing coarse dust and/or leaving the fine redn. agent dust in the gas to provide a neutral atmos. in (2). Part of the exhaust gas from (1) is pref. fed through a recuperator used to pre-heat air of combustion fed into (2); the exhaust gas from (1) may also be freed from dust, cooled and scrubbed in a washer to remove CO2, then used to replace part of the fuel in (2). Brown coal is inexpensive and permits a lower redn. temp. in (1). The invention is designed to obtain max. thermal efficiency from the brown coal.