GB677645A - Improvements in methods for the concentration of iron ore - Google Patents

Abstract

Ferric oxide-containing ores are treated with hydrochloric acid gas up to 400 DEG C to produce ferric chloride, which is separated by volatilization and treated with a small excess of steam at higher temperatures to produce ferric oxide, and hydrochloric acid for treatment of further ore. Hydrated oxidic ores may first be dehydrated at 300-500 DEG C; carbonate and magnetite ores should be roasted at 400-800 DEG C. As shown, the ore is chloridized with two to six times the theoretical amount of hydrochloric acid, preferably first at 100-200 DEG C, and then at 200-400 DEG C in the two-stage fluid bed reactor 6, 7 of Specification 677,690, and the gases pass via cyclones 29, 34 to a brick lined hydrolysis chamber 32 containing tubes 39 heated to 400-800 DEG C by gases from <PICT:0677645/III/1> combustion chamber 37. Superheated steam is injected through pipe 38. Ferric oxide deposited in the tubes passes to hopper 41 and is cooled, if desired, as a fluid bed or beds by air passing to combustion chamber 37. The evaporated gases, say 80 per cent hydrochloric acid and 20 per cent steam, pass via cyclone 43 and heat exchangers 45, 46 to condenser 47, whence the condensed solution passes to the heat exchangers 45, 46 to produce the superheated steam referred to. Steam from an external source may however, be employed. The evolved hydrochloric acid, with additional gas from reservoir 1 as may be required, is pumped to the chloridizing vessel 6, 7, some of it being heated in heat-exchanger 5 by the combustion gases escaping at 53 from the hydrolysis chamber 32. Cyclones 29, 34 and 43 may be disposed inside chambers 6, 7 and 32. The oxide produced may be reduced to iron, or may be mixed with less pure ores, and sintered, briquetted, &c. for use in a blast furnace. Specification 677,691 also is referred to.