| 摘要 |
<p>1,154,746. Fe containing pellets. ARTHUR G. McKEE & CO. 20 May, 1966 [22 June, 1965], No. 22659/66. Heading C1A. Fe-containing pellets are produced by passing green balls of an oxidic Fe material on a moving grate through a first drying zone, and tumbling the balls through a second reducing zone at a higher temperature so that at least some Fe is formed, hot gases being passed through both zones. The starting material may be ores or dust from steel-making furnaces, which is moistened and optionally mixed with 1-5% bentonite, up to 1% aqu. HCl, and up to 8% fine coke. Balls “-1 inch in diam. are formed in a balling disc or drum and undersized balls may be recycled. The balls are then heated at 250-800‹ F. on a moving grate through which hot air is drawn from above, and discharged into an inclined rotary kiln together with particles of coke or coal (50-100% by wt.). Combustion gases from a gas or fuel oil fire burner (containing excess O 2 ) pass in countercurrent and maintain a temperature of 1600- 2500‹ F. As, Zn and Pb impurities are removed. The exhaust gases may be passed through a heat exchanger to heat air (used in the first zone or as combustion air) and thence to dust removers e.g. bag filters. Alternatively, they may be mixed with exhaust air from the first zone, then passed to dust collectors, and then returned to the first zone. The balls are discharged from the kiln to a rotary water jacketed cooler where they are cooled to below 300‹ F. in an atmosphere containing C0 2 , CO, N 2 and inert gases (carried over from the kiln). They are then screened and separated magnetically from coke particles, the undersized balls and coke being recycled. The product is said to have a core of Fe and FeO with 15-30% porosity, and a coating 2-15 Á thick of FeO.</p> |
