Process for producing tantalum and columbium powder

The process of producing a metal powder of the group consisting of tantalum and columbium powders which comprises maintaining a liquid bath of a double salt of the formula

• R.sub.2 MX.sub.7
• wherein R is an alkali metal, M is a metal of the group consisting of tantalum or columbium and X is a halogen atom of the group consisting of fluorine, chlorine, or bromine, and a diluent comprising an alkali metal halide at a temperature above the liquidus temperature of said salt mixture but not exceeding 760.degree. C. in a closed reaction vessel, adding a molten alkali metal to said bath at a rate of at least 0.2 kg per kg of said double salt per hour during a nucleation period until a desired reaction temperature between 760.degree. C. and 1000.degree. C. is reached, the temperature rise during said nucleation period being at a rate of at least 10.degree. C. per minute, thereafter adding additional molten alkali metal to said bath at a rate of at least 0.1 kg per kg of said double salt per hour during a growth period while providing forced cooling to said bath at a rate of at least 10 kilocalories per minute per kilogram of said double salt, continuously agitating said liquid bath, continuously producing crystals of said metal M and collecting said crystals in a lower portion of said reaction vessel, said rate of alkali metal addition and said rate of forced cooling being balanced to maintain the reaction temperature in said growth period within 50.degree. C. of said desired reaction temperature but in excess of 760.degree. C.