GB658200A - Improvements in or relating to the reduction of ferruginous ores - Google Patents

Abstract

<PICT:0658200/III/1> Ferruginous ores &c. are treated for the conversion of their iron oxide content into magnetite by causing the comminuted ore to descend chambers in series, passing upwardly through the upper chamber a mixture of carbon dioxide, carbon monoxide and hydrogen at an elevated temperature below the liquidus temperature of the non-magnetic iron oxide compound in the ore, the volume and composition of the gas being such that at the temperature of operation, it is oxidizing with respect to FeO and Fe, is reducing with respect to Fe2O3 and is in equilibrium with Fe3O4, passing the treated ore material down the lower chamber in counter-current to a stream of reactive gas of such composition that after heating it is the same as the initial reactive gas, withdrawing the gas from the second chamber, heating it and using the heated gas for treatment of further ore material in the upper chamber. As shown, the ore is fed from a gas-seal hopper 22 into chamber 16, passing through it against a stream of reactive gas fed through bustle 12, and through a restricted conduit 7 into the second chamber 5 through which it passes to star-gate 40 against a stream of reactive gas entering from bustle 3. The "spent" gas from chamber 16 is circulated by blower 1 through a dust collector 26, cooler or scrubber 28 and, maybe, an electrostatic precipitator to the bustle 3, a certain amount of gas being bled through line 30 and fresh reducing gas being added through conduit 31. After traversing chamber 5, the gas passes through conduit 9 to a combustion chamber 10 wherein its temperature is raised to below 1300 DEG C. (at which the ore melts) by the combustion of fuel, e.g. oil, gas, powdered coke, &c. supplied to water-cooled burner 35 in just sufficient air supplied through bustle 33. The heated gas thereupon passes through conduit 11 to bustle 12. The volume of reactive gas may be 10 cu.ft. per lb. iron in the ore, and of the reducing component 1-1.37 cu.ft. per lb. iron. To ensure uniformity of the gas flow, gas-collecting pockets 4, 6, 14, 19 are provided within the chambers. Uniformity of solids flow within chamber 5 is ensured by conical baffles 45. The chambers 5, 16 may, if desired, be placed side by side, at any convenient levels, transfer of material being effected by bucket conveyers, &c. Prior to treatment, the ore material may be dried, using, for example, the equipment disclosed in Specification 647,490. The process is applicable to ores containing iron either as ferrous oxide or carbonate, or ferric oxide, and to blast furnace dust, which may be agglomerated prior to roasting. Specification 658,199 also is referred to.