| 摘要 |
<PICT:0949766/C3/1> Iron oxide is directly reduced to an iron-iron oxide product containing 70-100% metallic iron in an elongated, rotatable kiln 12 having a preheating zone 18, a reaction zone 21 and a discharging zone 25, by feeding a mixture of iron oxide pellets, e.g. of diameter 3-15 mm. and preferbly hard burned in an oxidizing atmosphere at 1000-1500 DEG C., solid carbonaceous material, such as high or low volatile coal, lignite, anthracite or coke fine, e.g. of particle size up to 12 mm., with or without a sulphur-binding flux, such as limestone or dolomite of grain size 1 -6 mm., into the preheating zone to heat it, e.g. by counterflowing hot exhaust gases from the reaction zone, advancing the mixture to the reaction zone wherein the temperature is 650-1200 DEG C. but below the incipient fusion temperature of the mixture and preferably wherein the partial pressure of CO is maintained in excess of that of CO2, supplying from 10-50% of the reducing reaction heat at spaced intervals along the length of the reaction zone 21 such as by using peripheral burners 19 fed with fuel and air and bent to point their nozzles 41 towards the discharging zone 25 so that the flames point countercurrent to the gas flow through the kiln, advancing the mixture to the discharging zone to discharge it prior to separating the iron-iron oxide pellets from the reaction mixture. Prior to separation, the discharged material, preferably containing between 0.1 and 0.15 Kg. of unburnt carbon for each Kg. of iron oxide pellets in the mixture, may be transferred to a rotary cooler 31 in which is maintained a reducing atmosphere such as CO fed from pipe 42 and discharged back into the discharging zone 25. The solid carbon content in the initial mixture is 120-150% of the theoretical amount required for complete reduction. |
