| 摘要 |
The present invention discloses a process for producing iron oxide pellets of low residual sulfur. In the pelletizing of finely divided ore with carbonaceous materials as binder, varying amounts of sulfur are introduced. Green pellets are heated under conditions leading to coking of the binder and recovery of the cracked vapors. The coked pellets are then further heated to achieve the desired degree of reduction and to diminish the residual sulfur content. A sulfur scavenger is initially sprayed on the ore. For pellets that will be reduced 85 percent or less, all necessary reductant is incorporated in the pellet, in the form of the coked binder and, optionally, added carbon. Heating to the reduction and calcining temperature is rapid. For highly reduced pellets (+85 percent), the same procedure may be followed, but heating to reduction and calcining temperature must be slow for good desulfurization. A preferred alternative for highly prereduced pellets involves reduction in two stages: initially a 25-50 percent reduction is carried out with rapid heating and with all reductant in the pellet. Then, the pellets are further reduced with a stoichiometric excess of reductant external to the pellet, with fast heating to reduction temperature. Because of the inherently porous nature of pellets produced with liquid carbonaceous binders, reduction is significantly faster and more complete than with conventional pellets.
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