Method for producing tantalum powder and tantalum powder obtained by the method
A method produces tantalum powder. The method includes: (1) uniformly mixing a tantalum powder raw material, metal magnesium and at least one alkali metal and/or alkaline earth metal halide, loading the mixture into a container, and putting the container in a furnace; (2) raising the temperature of the furnace to 600-1200° C. in the presence of inert gas, and soaking; (3) at the end of soaking, lowering the temperature of the furnace to 600-800° C., vacuumizing the interior of the furnace to 10 Pa or less, soaking under the negative pressure so that the excessive metal is separated; (4) thereafter, raising the temperature of the furnace to 750-1200° C. in the presence of inert gas, and soaking so that the tantalum powder is sintered in the molten salt after oxygen reduction; (5) then cooling to room temperature and passivating to obtain a mixed material containing halide and tantalum powder; and (6) separating the tantalum powder from the resulting mixture.
1 . A method for producing tantalum powder, the method comprising the steps of:
(1) uniformly mixing a tantalum powder raw material, metal magnesium and at least one alkali metal halide and/or alkaline earth metal halide, loading the mixture into a container, and putting the container in a heating furnace;
(2) raising the temperature of the heating furnace to 600-1200° C. in the presence of an inert gas, and soaking the mixture;
(3) at the end of soaking, lowering the temperature of the heating furnace to 600-800° C., vacuumizing an interior of the heating furnace to 10 Pa or less, and soaking under a negative pressure so that unreacted metal magnesium is separated;
(4) thereafter, raising the temperature of the heating furnace to 750-1200° C. in the presence of an inert gas, and soaking to melt the alkali metal halide and/or alkaline earth metal halide and obtain a molten salt, so that the tantalum powder is sintered in the molten salt after oxygen reduction, wherein the inert gas in step (4) is the same as or different from the inert gas in step (2);
(5) then cooling to room temperature and passivating to obtain a mixed material containing the alkali metal halide and/or alkaline earth metal halide and the tantalum powder; and
(6) separating the tantalum powder from the resulting mixture.
2 . The method according to claim 1 , characterized in that: a mass ratio of the tantalum powder to the alkali metal halide and/or alkaline earth metal halide in step (1) is 1:0.5-10.0, and/or the metal magnesium is added in an amount of 1-5% by weight of the tantalum powder.
3 . The method according to claim 2 , characterized in that: the alkali metal halide or alkaline earth metal halide in step (1) is one or more of NaCl, KCl, KF, KI and MgCl 2 .
4 . The method according to claim 1 , characterized in that: the alkali metal halide or alkaline earth metal halide in step (1) is one or more of NaCl, KCl, KF, KI and MgCl 2 .
5 . The method according to claim 1 , characterized in that: one or more compounds containing B, P and/or N elements are added as additive(s) in step (1) to dope the tantalum powder.
6 . The method according to claim 5 , characterized in that: the B element is added in an amount of 1-100 ppm; and/or the P element is added in an amount of 10-200 ppm; and/or the N element is added in an amount of 300-2500 ppm, with each ppm based on the weight of tantalum powder.
7 . The method according to claim 5 , characterized in that: the B element is added in an amount of 20-60 ppm; and/or the P element is added in an amount of 30-90 ppm; and/or the N element is added in an amount of 500-1200 ppm, with each ppm based on the weight of the tantalum powder.
8 . The method according to claim 1 , characterized in that: the inert gas in step (4) is the same as the inert gas in step (2).
9 . The method according to claim 1 , further comprising, after step (6), at least one of the following steps of high-temperature high-vacuum heat treatment and separating by acid washing, filtration and drying.
10 . The method according to claim 1 , characterized in that: the alkali metal halide or alkaline earth metal halide in step (1) is mixture of NaCl and KCl.
11 . The method according to claim 1 , characterized in that: in step (2), the temperature of the heating furnace is raised to 750-1000° C. and the mixture is soaked for 1-4 h.
12 . The method according to claim 11 , characterized in that: in step (3), the temperature of the heating furnace is lowered to 650-800° C., the interior of the heating furnace is vacuumized to 5 Pa or less, and the soaking under the negative pressure is conducted for 1-10 h.
13 . The method according to claim 12 , characterized in that: in step (4), the temperature of the heating furnace is raised to 900-1050° C. and the soaking is conducted for 1-10 h.
14 . The method according to claim 1 , characterized in that: the mass ratio of the tantalum powder to the alkali metal halide and/or alkaline earth metal halide in step (1) is 1:0.5-3.0, and/or the metal magnesium is added in an amount of 1.5-3% by weight of the tantalum powder.