| 摘要 |
<p><PICT:0980425/C1/1> Ferrous oxide is prepared from ores of higher oxides of iron by reacting a methane-rich gas (i.e. containing at least 25% methane) in a combustion zone with air in proportions for incomplete combustion to form a reducing gas stream, passing the reducing gas stream countercurrent to and in contact with an ore of higher oxides of iron in a reducing zone thereby reducing the ore to ferrous oxide, withdrawing the gaseous effluent from the reducing zone, dividing it into two approximately equal portions, burning one of the portions completely with air in recuperative heat exchange with the other portion and recycling and mixing the thus heated second portion with the reducing gas stream and/or with the methane-rich gas stream, so that the temperature within the combustion zone is approximately 1000 DEG C. As shown in Fig. 3, the iron is charged by a screw 2 from a hopper 3, to a gas-tight rotary furnace 1 having an axial burner supplied with a methane rich gas and air through tubes 10 and 11 respectively. The reduced ore is poured into a tank 4, containing hot water, through a submerged shoot 5, and a chain of buckets 7 or an endless apron removes the oxide and discharges it to a rotary screen 8 in which it dries instantaneously. The gas escaping from the furnace is divided into two substantially equal portions by valves 18 and 19. Air, supplied by fan 20 is added to one of the portions and the mixture burnt in the hearth of heat recuperator 21, the flames passing along tubes 26. The second portion is drawn in by fan 25 and forced through tubes 26 and thus heated to about 760 DEG C. This-hot gas is then sent into the peripheral sheath 12 of the burner.</p> |
