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Method for Preparing Ferrochromium Alloys by Vacuum Reduction and Simple Melting of Reduced Products.
Pahlman-JE; Boucher-ML; Payne-SL; Khalafalla-SE
MISSING :22 pages
As part of its effort to reduce the need for strategic minerals through conservation and to reduce the capital and energy requirements of mineral processing, the Bureau of Mines has investigated a method for preparing ferrochromium alloys containing less than 2 percent carbon. This method will conserve chromium and should reduce the capital and energy requirements for chromite reduction. Reduced products containing less than 2 wt-pct c and as low as 0.01 wt-pct c were obtained by reacting pellets of chromite and carbonaceous reductant mixtures at pressures of 0.1 to 1 torr and temperatures of 1,230 deg. to 1,320 deg. C. The extent of reduction increased with increased temperature and decreased pressure; however, operating conditions were limited due to the onset of significant chromium vaporization at higher temperatures and lower pressures. Foundry coke, anthracite, and carbon black were found to be superior to graphite as reductants. The reduction of chromite to metallics was found to proceed via the carbide intermediates (fe,cr)7c3 and (fe,cr)23c6. No evidence of carbide intermediates fe3c or cr3c2 was found. Buttons of ferrochrome alloys were made by melting a mixture of reduced products with cao and sio2 at 1,700 deg. C for 20 minutes in an induction furnace.
IH; Report of Investigations
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division