Reduction of CO{sub}2 emissions as a result of using hydrogen-rich reduction gases for producing direct reduced iron

摘要

The use of hydrogen-rich gases such as natural gas or coke oven gas as a reduction agent for the production of direct reduced iron (DRI) as well as its processing to steel in an electric arc furnace, will open up new possibilities to lower the CO{sub}2 emission per t of steel to results which will be substantially below those achieved in conventional crude steel production via the blast furnace/BOF route. While the conventional way in spite of optimally adjusted process conditions (<300 kg coke/t of hot metal) will result in a CO{sub}2 emission of about 1 600 kg CO{sub}2/t of crude steel, direct reduction on natural gas basis with the electric arc furnace will enable a reduction of emissions between 29 and 39 % down to 1135 - 962 kg CO{sub}2/t of crude steel. The use of hydrogen being processed by coke oven gas will lead to results of about 780 kg CO{sub}2/t of crude steel. Considering that coke oven gas is only available in integrated iron and steel plants (blast furnace/ coke oven plant), the integration of a DR plant into an existing iron and steel plant with a coke oven plant, with the direct use of the (partly cleaned) coke oven gas without separating the hydrogen, will achieve results of 1 230 kg CO{sub}2/t of crude steel, with the DRI being melted in an electric arc furnace. The production of hydrogen from coal or heavy fuel oil for later use as a reduction agent in the production of DRI leads only to a minimal reduction of the specific CO{sub}2 emission.