Process for producing niobium and tantalum compounds
View Patent ↗A process for producing valve metal oxides, such as tantalum pentoxide or niobium pentoxide with a narrow particle size distribution within a desired particle size range, is provided. According to the process of the present invention, the valve metal fraction from digestion of valve metal material containing ore is processed under controlled temperature, pH, and residence time conditions to produce the valve metal pentoxide and pentoxide hydrates. Also, disclosed are new tantalum pentoxide and niobium pentoxide products and new tantalum pentoxide precursors and niobium pentoxide precursors.
1. A calcined tantalum pentoxide powder characterized by having:
a BET surface area of less than or equal to 3 m 2 /g; and
a packed bulk density of greater than 3.0 g/cc.
2. The calcined tantalum pentoxide powder of claim 1 wherein the BET surface area is less than or equal to 0.4 m 2 /g.
3. The calcined tantalum pentoxide powder of claim 1 wherein the packed bulk density is greater than or equal to 4.0 g/cc.
4. The calcined tantalum pentoxide powder of claim 1 , wherein the BET surface area is from 0.3 m 2 /g to 3 m 2 /g.
5. The calcined tantalum pentoxide powder of claim 1 , wherein the BET surface area is less than or equal to 0.75 m 2 /g.
6. The calcined tantalum pentoxide powder of claim 1 , wherein the packed bulk density is from greater than 3.0 g/cc to 4 g/cc.
7. The calcined tantalum pentoxide powder of claim 1 , wherein the packed bulk density is greater than or equal to 3.8 g/cc.
8. The calcined tantalum pentoxide powder of claim 1 , wherein said calcined tantalum pentoxide powder has a size such that 70% or less of said powder has a size less than 1 micrometer.
9. The calcined tantalum pentoxide powder of claim 1 , wherein said calcined tantalum pentoxide powder has a size greater than 1 micrometer.
10. The calcined tantalum pentoxide powder of claim 1 , wherein said calcined tantalum pentoxide powder comprises a fine single crystallite shape.
11. The calcined tantalum pentoxide powder of claim 1 , wherein said calcined tantalum pentoxide powder comprises spherical agglomerates.
12. The calcined tantalum pentoxide powder of claim 1 further comprising a fluoride content of less than or equal to 500 ppm.
13. The calcined tantalum pentoxide powder of claim 1 further comprising a fluoride content of less than or equal to 150 ppm.
14. A calcined tantalum pentoxide powder characterized by having:
a BET surface area of greater than or equal to 3 m 2 /g; and
a packed bulk density of less than or equal to 3.0 g/cc.
15. The calcined tantalum pentoxide powder of claim 14 wherein the BET surface area is greater than or equal to 11 m 2 /g.
16. The calcined tantalum pentoxide powder of claim 14 wherein the packed bulk density is less than or equal to 1.1 g/cc.
17. The calcined tantalum pentoxide powder of claim 14 , wherein the BET surface area is from 3.0 m 2 /g to 11 m 2 /g.
18. The calcined tantalum pentoxide powder of claim 14 , wherein the BET surface area is greater than or equal to 7.0 m 2 /g.
19. The calcined tantalum pentoxide powder of claim 14 , wherein the packed bulk density is from 0.75 g/cc to 3.0 g/cc.
20. The calcined tantalum pentoxide powder of claim 14 , wherein the packed bulk density is from 1.1 g/cc to 3.0 g/cc.
21. The calcined tantalum pentoxide powder of claim 14 , wherein the packed bulk density is less than or equal to 0.75 g/cc.
22. The calcined tantalum pentoxide powder of claim 14 , wherein said calcined tantalum pentoxide powder has a size such that 70% or less of said powder has a size less than 1 micrometer.
23. The calcined tantalum pentoxide powder of claim 14 , wherein said calcined tantalum pentoxide has a size such that greater than 9% of said calcined tantalum pentoxide powder has a size less than 1 micrometer.
24. The calcined tantalum pentoxide powder of claim 14 , wherein said calcined tantalum pentoxide powder comprises a fine single crystallite shape.
25. The calcined tantalum pentoxide powder of claim 14 , wherein said calcined tantalum pentoxide powder comprises spherical agglomerates.
26. The calcined tantalum pentoxide powder of claim 14 , further comprising a fluoride content of less than or equal to 500 ppm.
27. The calcined tantalum pentoxide powder of claim 14 , further comprising a fluoride content of less than or equal to 150 ppm.