Steel mfr. by direct redn. of iron ore dust - using hydrogen contg. small amt. of carbon mon:oxide in vertical redn. shaft leading to arc furnace

摘要

The dust is fed into a gas (17) consisting mainly of H2 and preheated to 400-800 degrees C. The gas carries the dust into a vertical redn. shaft heated internally to 1000-1400 degrees C. to form metallic iron falling into a molten bath of iron which is pref. in an arc furnace. Gas (17), which also contains a monoxide, is pref. preheated via heat exchange with the exhaust gases leaving the redn. shaft via the arc furnace. Fresh redn. gas pref. formed from natural gas and steam is added continuously to gas (17), which pref. also contains recycled gas leaving the furnace and fed through CO2 and CO washers. Gas (17) pref. contains 5-10 vol.% monoxide, and the redn. shaft is pref. heated via electrodes. The number of mfg. steps is reduced; and the high H2 content of gas (17) provides high redn. efficiency, esp. at 1200 degrees C.