METHOD FOR MAKING POWDER OF VALVE METAL Russian patent published in 2002 - IPC

FIELD: non-ferrous metallurgy, possibly manufacture of highly purified powders of tantalum and niobium with large specific surface areas for making capacitors. SUBSTANCE: method comprises steps of realizing interaction in reaction vessel in inert-gas atmosphere of valve metal compound, alkali metal halide and melt alkali metal at elevated temperature; agitating them at reducing valve metal; cooling erection mass; disintegrating it and washing out powder of valve metal by removing respective salts out of it. According to invention method comprises steps of preliminarily mixing valve metal compound with alkali metal halide at molar ratio of components respectively (0.2-4) : 1 and feeding in powdered state; reducing valve metal at temperature no more than 850 C; obtaining mixture of valve metal and alkali metal halide by one or several batches continuously added to melt of alkali metal; before feeding mixture of valve metal and alkali metal halide, additionally providing under melt of alkali metal melt of alkali metal halide in quantity no more than 40% of mass of valve metal compound; using tantalum or niobium as valve metal; using as compound of valve metal potassium fluorotantalate or potassium fluoroniobate; using as alkali metal sodium, potassium or their mixture; using as alkali metal halide sodium chloride and/or potassium chloride. Such method provides increase of specific surface area by 1.4-3.7 times, increase of charge by 1.3-1.9 times. EFFECT: enhanced quality of powder. 8 cl, 1 tbl, 5 ex