초록 ▼

A method of preparing primary refractory metals (e.g., primary tantalum metal) by contacting a particulate refractory metal oxide (e.g., tantalum pentoxide) with a heated gas (e.g., a plasma), is described. The heated gas comprises hydrogen gas. The temperature range of the heated gas and the mass r

A method of preparing primary refractory metals (e.g., primary tantalum metal) by contacting a particulate refractory metal oxide (e.g., tantalum pentoxide) with a heated gas (e.g., a plasma), is described. The heated gas comprises hydrogen gas. The temperature range of the heated gas and the mass ratio of hydrogen gas to refractory metal oxide are each selected such that: (i) the heated gas comprises atomic hydrogen; (ii) the refractory metal oxide feed material is substantially thermodynamically stabilized (i.e., the concurrent formation of suboxides that are not reduced by atomic hydrogen is minimized); and (iii) the refractory metal oxide is reduced by contact with the heated gas, thereby forming primary refractory metal (e.g., primary tantalum metal and/or primary niobium metal).

대표청구항 ▼

What is claimed is: 1. A method of preparing a primary refractory metal comprising: (a) heating a gas comprising a reactive gas, said reactive gas comprising hydrogen gas, thereby forming a heated gas having a temperature range; and (b) contacting a particulate refractory metal oxide with said heat

What is claimed is: 1. A method of preparing a primary refractory metal comprising: (a) heating a gas comprising a reactive gas, said reactive gas comprising hydrogen gas, thereby forming a heated gas having a temperature range; and (b) contacting a particulate refractory metal oxide with said heated gas, wherein, (i) said temperature range of said heated gas, and (ii) a weight ratio of the hydrogen gas of said heated gas to said particulate refractory metal oxide, are each selected such that, said heated gas comprises atomic hydrogen, said refractory metal oxide is substantially thermodynamically stabilized, and said refractory metal oxide is reduced by atomic hydrogen in step (b), thereby forming said primary refractory metal, and wherein said refractory metal oxide is tantalum pentoxide or niobium pentoxide and has a carbon content of less than 10 ppm. 2. The method of claim 1 wherein at least 90% by weight of said particulate refractory metal oxide is reduced and formed into primary refractory metal in step (b) and said heated gas is substantially free of ionic hydrogen. 3. The method of claim 1 wherein said heated gas is a plasma, said plasma being formed from a feed gas comprising an inert gas and said reactive gas, and said particulate refractory metal being contacted with said plasma in step (b). 4. The method of claim 3 wherein said inert gas is selected from the group consisting of group VIII noble gasses of the periodic table of the elements, and combinations thereof and said particulate refractory metal oxide is contacted with said plasma by introducing said particulate refractory metal oxide into said plasma. 5. The method of claim 1 wherein the reactive gas comprises substantially 100 percent by weight of hydrogen gas and said particulate refractory metal oxide is contacted with said heated gas in the presence of a catalyst. 6. The method of claim 5, wherein said catalyst is a particulate catalyst comprising a metal selected from the group consisting of palladium, platinum, iridium, ruthenium, rhodium, combinations thereof and alloys thereof. 7. A method of preparing primary tantalum metal comprising: (a) heating a gas comprising a reactive gas, said reactive gas comprising hydrogen gas, thereby forming a heated gas; and (b) contacting particulate tantalum pentoxide with said heated gas at a temperature of 1900 K to 2900 K, thereby reducing said particulate tantalum pentoxide and forming primary tantalum metal; wherein the hydrogen gas of said heated gas and said particulate tantalum pentoxide contacted with said heated gas have a mass ratio of hydrogen gas to particulate tantalum pentoxide of greater than 1.5:1, and wherein said tantalum pentoxide has a carbon content of less than 10 ppm. 8. The method of claim 7 wherein the reactive gas comprises substantially 100 percent by weight of hydrogen gas and said mass ratio of hydrogen gas to particulate tantalum pentoxide is at least 4:1. 9. The method of claim 7 wherein said mass ratio of hydrogen gas to particulate tantalum pentoxide is at least 9:1, and the particulate tantalum pentoxide is contacted with said heated gas at a temperature of 1900 K to 2700 K. 10. The method of claim 7 wherein at least 98% by weight of said particulate tantalum pentoxide is reduced and formed into particulate primary tantalum metal in step(b). 11. The method of claim 7 wherein said heated gas is a plasma, said plasma being formed from a feed gas comprising an inert gas and said reactive gas, and said particulate tantalum pentoxide being contacted with said plasma in step (b) and said inert gas is selected from the group consisting of group VIII noble gasses of the periodic table of the elements, and combinations thereof. 12. The method of claim 11 wherein said particulate tantalum pentoxide is contacted with said plasma by introducing said particulate tantalum pentoxide into said plasma. 13. The method of claim 7 wherein said tantalum pentoxide is substantially pure tantalum pentoxide. 14. The method of claim 7 wherein said process is conducted at substantially atmospheric pressure. 15. A method of preparing primary niobium metal comprising: (a) heating a gas comprising a reactive gas, said reactive gas comprising hydrogen gas, thereby forming a heated gas; and (b) contacting a particulate oxide of niobium comprising niobium pentoxide having a carbon content of less than 10 ppm, with said heated gas at a temperature of 2100 K to 2700 K, thereby reducing said particulate oxide of niobium and forming primary niobium metal; wherein the hydrogen gas of said heated gas and said particulate oxide of niobium contacted with said heated gas have a mass ratio of hydrogen gas to particulate oxide of niobium of at least 9:1. 16. The method of claim 15 wherein at least 90% by weight of said particulate oxide of niobium is reduced and formed into primary niobium metal in step (b). 17. The method of claim 15 wherein the primary niobium metal formed is particulate primary niobium metal. 18. The method of claim 15 wherein said heated gas is a plasma, said plasma being formed from a feed gas comprising an inert gas and said reactive gas, and said particulate oxide of niobium being contacted with said plasma in step (b). 19. The method of claim 18 wherein said inert gas is selected from the is group consisting of group VIII noble gasses of the periodic table of the elements, and combinations thereof. 20. The method of claim 18 wherein said particulate oxide of niobium is contacted with said plasma by introducing said particulate oxide of niobium into said plasma. 21. The method of claim 15 wherein the reactive gas comprises substantially 100 percent by weight of hydrogen gas. 22. The method of claim 15 wherein said process is conducted at substantially atmospheric pressure and said oxide of niobium is substantially pure niobium pentoxide.