| 摘要 |
Iron oxide particles, e.g. ground haematite or magnetite containing 67-69% combined Fe, are reduced to sponge iron in fluidized beds with a counter-current flow of hydrogen-rich gas by partially reducing the iron oxide to iron, e.g. to 60-75% eliminated oxygen, at a maximum temperature of 750 DEG C., cooling the iron oxide-iron mixture to a maximum temperature of 250 DEG C., reheating the mixture e.g. to 380-450 DEG C., and finally reducing the remaining unreduced oxide, e.g. to 90-99% eliminated oxygen, at a maximum temperature of 580 DEG C. Initially the particles may be pre-heated to 900-1000 DEG C. and the reducing gas to 800-850 DEG C. The partial reduction may be carried out in two stages in series with reduction to FeO in upper stage. Preferably, part of the reducing gas from the final reduction is recycled back and part (after water vapour removal) is added to the partial reduction circuit. |
