| 摘要 |
<p>1,245,991. Iron oxide film. ESSO RESEARCH & ENG. CO. 31 Oct., 1968 [10 Jan., 1968], No. 51610/68. Heading C1A. [Also in Division C7] Highly reactive reduced iron ore from a direct iron ore reduction process is provided with a passivating oxide film by exposing the reduced ore at a temperature above 1058‹ F. to an atmosphere having an oxidation potential sufficient to form a thin wustite coating on the surface thereof and then quenching and maintaining it in an inert atmosphere at 400‹ to 1100‹ F. for a time sufficient to disproportionate said wustite coating, whereby a protective film of the inverse spinel form of magnetite is formed. Particulate iron produced by fluidized bed reduction of powdered iron ore may be oxidized in H 2 /steam at 1200-1600‹ F. to give a wustite film 20-10,000 Š thick, and quenched in nitrogen for ¢-15 minutes so that the wustite disproportionates to iron and magnetite.</p> |
