GB762652A - Metallurgy - Google Patents

Abstract

Carbides of Cr, Mn, Ti, Mo, W, V, Zr or Hf or mixtures thereof or products containing one or more of these metals and not less than 2 per cent of C such as high-carbon ferro alloys or products containing one or more of these metals partially in the form of carbides are reacted in finely divided form with a finely divided oxide of another metal whose boiling point is lower than that of the metal of the carbide, the oxide being present in amount at least 1.33 times that theoretically required to react with the carbon, the reaction being carried out in vacuo at a temperature sufficient to cause reduction of the oxide and vaporisation of the metal thereof, e.g. under a pressure lower than 1 mm. of mercury and a temperature of 1760-2000 DEG F. The oxide used may be of Cd, Zn, Mg, Tl, Bi, or Pb, In examples given high-carbon ferro chromium and high-carbon ferro manganese are used as the other constituent of the reaction mixture. The mixture, which may be used in the form of briquettes, may contain also an oxidation promoter selected from the group consisting of halogen acids, boric acid, boric anhydride, sodium borates and sodium hydroxide. The residue in the retort contains the metal of the carbon-containing constituent partly in the form of oxide and partly in the form of a metal products low in carbon.