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US 4,306,905 AGranted
Production of ferrochromium alloys
AssigneeThe United States of America as represented by the Secretary of the Interior
InventorsJohn E. Pahlman, Sanaa E. Khalafalla
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Abstract
Ferrochromium alloys are prepared by vacuum reduction of chromite concentrate by means of a carbonaceous reductant, followed by melting in the presence of slag-forming materials to produce the alloy and a separate slag phase. Preferably, CaO is employed as an ingredient in both the reduction step and the melting step.
Claims9
A process for production of ferrochromium alloys from chromite concentrate comprising:
- (a) admixing and blending the concentrate, in finely divided form, with a finely divided carbonaceous reductant and a finely divided binder consisting essentially of chromic acid,
- (b) pelletizing the blended mixture to form porous pellets suitable for reaction in a vacuum furnace,
- (c) heating the pellets in said furnace at elevated temperature and reduced pressure for a time sufficient to effect reduction of the chromite with minimum vaporization of chromium,
- (d) admixing the reduced product from step (c) with slag composition-adjusting additives in amounts sufficient to lower the fusion temperature of gangue material in the reduced product, and
- (e) heating the admixture from step (d) at a temperature and for a time sufficient to melt the components thereof and form separate ferrochromium alloys and slag phases.
2 more elements
Dependencies are inferred from the claim text.