Process and Cell for the Production of Chromium of Low Carbon Content by Means of Fused Eelctrolytic Extraction and Chromium and Chromium Alloy Obtained Thereby.

摘要

1,190,679. Producing chromium from fused electrolyte. UNIVERSITE LIBRE DE BRUXELLES. May 15, 1968 [May 19, 1967], No.23150/68. Heading C7B. Chromium metal or alloy (e.g. ferrochrome) with a maximum carbon content of 0À1% is produced by a fused electrolyte process using an electrolyte formed of either a ternary system selected from Cr 3 O 3 and two of CaO, MgO, Al 2 O 3 and SiO 2 or a quaternary system selected from Cr 2 O 3 and three of CaO, MgO, Al 2 O 3 and SiO 2 . Preferably the ratio of CaO + MgO to SiO 2 + Al 2 O 3 is at least 0À75. e.g. a mixture comprising 46% lime, 6À3% magnesia and 47À7% alumina may be used for dissolving up to 30% or more Cr 2 O 3 ; or a mixture comprising 43À5% lime, 10% magnesia, 23À25% each of alumina and silica for dissolving ferrochromite. The electrolyte may contain impurities of other oxides or salts, e.g. BaO, B 2 O 3 , NaF or CaF 2 . As shown, the electrolytic cell comprises a container, e.g. a steel water-cooled casing 1, above which is mounted at least one carbon (e.g. graphite) anode 10, the chromium (alloy) melt forming the cathode 9 in a cavity at the container bottom into which terminates at least one cathodic current lead, e.g. of copper tube 5, cooled, e.g. internally by water circulation through pipes 6, 7, so as to be coated with a solidified layer 17, e.g. above steel component 8 screwed in the top of the tube 5, and the above electrolyte 11 floating above the cathode. The bottom and internal walls 4 of the container may be of calcined dolomite or magnesia and lined with a crust of solid electrolyte 18. Reducing atmosphere is preferably maintained in the cell.