| 摘要 |
The present invention relates to a process for the direct reduction of iron ore performed by means of a plant comprising a gravitational furnace (2) having at least one iron ore reduction zone (8) in the upper part thereof, and at least one carbon deposition zone (9) and one reduced metal product cooling zone (10) in the lower part thereof, and means for feeding a reducing gas mixture into the reactor in correspondence with the reduction zone, means for recycle exhaust or reactor off gas from the reactor to syngas and mixing the recycled gas with natural gas to form a reducing gas mixture. According to the invention in first reformation step (5) unreacted carbon monoxide CO and steam present in the reactor off gas is reformed to carbon dioxide and hydrogen following the water gas shift reaction CO+HO=CO+H, in a secondary reformation step the de-watered reactor off gas comprising mainly of carbon dioxide and hydrogen is processed to remove carbon dioxide, and in a third reformation step physical separation of both nitrogen and carbon oxide CO from the reducing syngas is carried out to bring down the levels of CO and any existing other gases in the recycled gas to as low level as possible such that recycled reducing gas is as close to pure hydrogen Has possible. |
