ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Influence of Coating Oxide and Sulfur Pressure on Sticking during Fluidized Bed Reduction of Iron Ores
Shoji HayashiSatoshi SawaiYoshiaki Iguchi
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1993 Volume 33 Issue 10 Pages 1078-1087

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Abstract

In order to avoid sticking during a fluidized bed reduction of iron ores and elucidate its mechanism, their reduction tests using two types of easily sticked ores coated by a water-slurry consisting of each submicron reagen of gangue species were carried out at 900°C by N2-H2 mixtures having sulfur activities incapable of forming FeS, where fibrous irons are known to be predominated from the authors' previous researches.
Without coating, ores sticked mostly due to fibrous morphology and/or high surface energy of iron. With coating, ores kept fluidizing mainly due to the physical spacer effect among ore surface. Al2O3 and MgO were effective agents, while CaO was ineffective due to nonuniform coating and preferential upward growth of irons. Particularly, the conditions near as=0.1 in a bed (as: sulfur activity in gas phase relative to Fe/FeS equilibrium) increased fairly the coating amount necessary to improve fluidization, because such conditions promote most fibrous irons. It was found that the coating amounts required to improve fluidization increase with fibrous iron morphology, active iron surface, and less original gangue coverage. Coating traces of ore tail rich in Al2O3 and SiO2 species was also effective for fluidization.

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© The Iron and Steel Institute of Japan
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