Beneficiation of low grade iron ores

摘要

1,219,980. Facilitating magnetic separation. HYDROCARBON RESEARCH Inc. 17 June, 1968 [16 June, 1967], No. 28814/68. Heading C1A. [Also in Division C7] Low grade iron ore such as limonite or siderite is contacted, possibly in several stages, with reducing gas, preferably containing at least 50% by volume of hydrogen with or without carbon monoxide, at 850-1700‹ F. and is then heated at 1800-2200‹ F. for 10 minutes to 2 hours in a non-oxidizing gas, after which the reduced ore is ground and submitted to magnetic separation. Sintering during the second heating step may be prevented by the addition of up to 1% of carbon. Reduction may be effected in a fixed or fluidized bed, and typical conditions are a gas pressure of 200-400 p.s.i. with a flow rate of 5 to 15 feet. per second.