GB771139A - Improvements in or relating to the manufacture of refractory metals - Google Patents

Abstract

Refractory metals having a melting point higher than 1830 DEG F., e.g. Cr, Ti and Zr, are manufactured by interacting CaC, and a non-volatile oxide, sulphide, or oxidized or sulphurized ore of the metal in the presence of a flux and at a temperature substantially lower than the melting point of the metal, and preferably at a temperature not substantially higher than the melting point of the flux. The latter may be boric anhydride, alkali metal chloride calcium chloride, simple or compound fluorides, borates or fluoborates. The reagents may be intimately mixed, but preferably are disposed in successive layers, the flux being uppermost, and preferably with an excess of CaC2. The reaction mass may be diluted with a substance inert under the operating conditions, e.g. CaO. The reaction may be carried out in a refractory steel retort of tapered shape with removable bottom and cover members, and four suitable retorts are described and illustrated in the Specification. When the reaction is complete lime and flux are removed by washing in water which may be acidified, the carbon is removed by froth flotation, the silica is removed by using a liquid of density between that of the metal and silica, and the last impurities are removed by washing with HNO3, thereby leaving a spongy metal powder. Iron metal by magnetic separation followed by treatment with an acid which does not attack the refractory metal.