GB677904A - Improvements in separation of iron from its ores - Google Patents

Abstract

In obtaining iron by treating a ferric acid to form ferric chloride and then reducing this with hydrogen, an excess of the reacting gas is supplied to each reaction vessel as part of a mixture of the two gases, the mixture leaving the chloridizing vessel flowing in a circulation system back <PICT:0677904/III/1> to the chloridizing vessel, and part at least of it, whilst so flowing, being enriched in hydrogen and then used as the mixture introduced into the reducing vessel. As shown, iron ore, roasted at 300-500 DEG C to remove water or to decompose carbonates, is fed to the upper chamber 6 of a vessel 4 wherein it is partially chloridized at 100-200 DEG C with a 50-66 per cent HCE-50-34 per cent H2 mixture. The steam produced, excess hydrochloric acid, hydrogen and a small amount of volatilized ferric chloride pass to cyclone 29 and condenser 36, wherein a dilute hydrochloric acid collects, the gas remaining passing to gasholder 38. The partially chloridized ore passes to a lower chamber 7 wherein chloridization is completed at 250-400 DEG C. Specifications 677,690 and 677,691 are referred to in connection with the chloridization. The gases are cooled to 150-200 DEG C in chamber 40, the distilled ferric chloride being deposited as almost dry crystals, and being passed therefrom to reduction chamber 42. The gases pass to water-cooled condenser 44, wherein aqueous hydrochloric acid collects, the gases passing to a second gas holder 46 wherein they are enriched by hydrogen chloride obtained by treating with sulphuric acid, in vessel 69, the aqueous hydrochloric acid from condensers 36, 44. The hydrochloric acid-rich gas from holder 46 is mixed at 1 with gases from the reduction of the ferric chloride, and is pumped to the chloridizing vessel 4, the part of the gas passing to the lower chamber 47 being preheated to about 300 DEG C in heat exchanger 5. The hydrogen-rich gas from holder 38 is pumped to vessel 42 wherein the ferric chloride is reduced to sponge iron, being joined at point 56 by hydrogen which is preheated by passage over the iron discharged in hopper 50. The reduction vessel comprises an upper chamber 47 and lower 48, the gas passing via heat exchanger 54 to the former wherein reduction is effected at 300-500 DEG C and then via heat exchanger 60 to the latter wherein reduction is effected at 500-800 DEG C. Heat exchanger 60 is supplied with gases from combustion chamber 63, which then pass to preheater 5.