CH_4ガスに随伴された微粉鉱石の高速輸送還元(製銑)

概要

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Acceleration of reduction rate and decrease of reaction temperature in ironmaking process are key issues to reduce the CO_2 emission and the energy consumption. To solve the problem, effective use of H_2 gas or CH_4 gas including both reducing agent of carbon and hydrogen is proposed. Therefore, a laboratory scale fine iron ore particles-gas conveyed system was utilized to measure the reduction rates of fine ore by using H_2 and CH_4 gas at high temperature. H_2-N_2 and CH_4-N_2 mixture having various flow rates and compositions were flowed downward with fine iron ore through a cylindrical reactor maintained at a constant temperature of 1373 to 1723K. The reduction process was found to proceed in such manner that the iron ore particles were reduced topochemically under the condition of 1573K. The reduction rate in CH_4 gas became larger than that in H_2 gas with increase in the temperature, because of the contribution of carbon deposited on the surface of iron ore particle. Fractional reduction of ore in CH_4 gas reached over 0.8 at 1573K in 1s. In the reaction rate analysis, it was concluded that the major fraction of overall reaction resistance was attributable to chemical reaction between the iron oxide and the carbon dissolved in metallic iron. The activation energy in CH_4 reduction was evaluated to be 192.5kJ/mol and it was almost same as that in decomposition of CH_4.
社団法人日本鉄鋼協会の論文
2005-06-01