GB870930A - Improvements in and relating to the production of columbium and tantalum - Google Patents

Abstract

Tantalum or niobium is produced by (a) preparing a powdered mixture (1-40 m particle size) of carbonaceous reducing agent and an oxide of the required metal, the oxide being present in an excess up to 15% of the stoichiometric proportion, (b) heating the mixture, under reduced pressure and at such a rate that the formation of fused suboxidic compounds is avoided, to a temperature between 2000 DEG C. and the melting point of required metal until substantial evolution of gas ceases and (c) cooling the resultant metal under noncontaminating conditions. The metal oxide is preferably niobium or tantalum pentoxide and the reducing agent graphite, lampblack, acetylene black or thermatomic carbon. The mixture may be heated in an induction furnace and the preferred rate of temperature increase is 150-300 DEG C. per hour. The metal is cooled in the furnace, initially under vacuum and finally under an inert gas e.g. helium or argon. Oxides of readily volatilized metals e.g. calcium, barium, strontium and aluminium may be added to the reaction mixture and the mixture may be compacted at 1500lbs. per square inch before heating to provide a massive product.