Claims
- 1. A metal reduction process of electrochemically producing electrode product from metal oxide during electrolysis in a molten salt composition, comprising providing an anode having an extended surface area for the selective evolution of gaseous electrode product, the metal oxide having a solubility <1 wt. % in the molten salt composition.
- 2. The process of claim 1 wherein the gaseous product comprises oxygen or carbon oxide.
- 3. The process of claim 1 wherein the anode comprises a plurality of interior holes to increase the surface area of the anode.
- 4. The process of claim 3 wherein the holes create a 15 to 75% void volume in the anode and extend through the anode.
- 5. The process of claim 3 wherein the holes are dimensioned to provide gas-lift pumping of the molten salt composition through the channels.
- 6. The process of claim 1 wherein the extended surface area is at least about 2 times that of the superficial area of the anode.
- 7. The process of claim 1 wherein the extended surface area is at least about 30 times that of the superficial area of the anode.
- 8. The process of claim 1 wherein the salt composition comprises metal chlorides or metal fluorides, or both, in the amount of from about 0 to about 100% metal chlorides, 0 to about 100% metal fluorides, and having a liquidus temperature less than about 900.degree. C., and the electrolysis comprises deposition of molten aluminum and evolution of oxygen or carbon oxide as electrode product.
- 9. The process of claim 1 wherein the salt composition comprises lithium fluoride, magnesium fluoride and calcium fluoride which is molten at less than about 850.degree. C.
- 10. The process of claim 1 wherein the salt composition comprises sodium chloride, potassium chloride, and cryolite.
- 11. The process of claim 1 wherein the salt composition comprises about 42.75% sodium chloride, about 42.75% potassium chloride, and about 12.5% cryolite.
- 12. The process of claim 1 wherein the anode comprises carbon which is consumed during the electrolysis.
- 13. The process of claim 1 wherein the anode faces a cathode comprising molten metal.
- 14. The process of claim 1 wherein the electrode product further comprises a metal or metal alloy.
- 15. The process of claim 1 wherein the anode is consumed during the electrolysis.
- 16. The process of claim 1 wherein the anode is inert during the electrolysis.
- 17. A process as claimed in claim 16 wherein said inert anode comprises a cermet material.
- 18. The process of claim 1 wherein the salt composition contains a fluoride.
- 19. The process of claim 18 wherein the fluoride comprises cryolite, potassium fluoride or calcium fluoride.
- 20. The process of claim 1 wherein temperature at a sidewall-molten salt interface is above the liquidus temperature of the molten salt composition, whereby there is no frozen sidewall.
- 21. The process of claim 1 wherein alumina is present as metal oxide in a concentration range 0.1 to 2%.
- 22. The process of claim 1 wherein the molten salt composition executes a circulation pattern for suspending and circulating undissolved particles of metal oxide.
- 23. The process of claim 1 wherein a molten metal cathode rests on a floor of graphitic carbon and the molten metal cathode contains alkali metal constituents.
- 24. The process of claim 1 wherein superficial anode current density is greater than 1 ampere/square inch.
- 25. The process of claim 24 wherein superficial anode current density is greater than 2 amperes/square inch.
- 26. The process of claim 25 wherein superficial anode current density is greater than 3 amperes/square inch.
- 27. The process of claim 26 wherein superficial anode current density is greater than 4 amperes/square inch.
- 28. The process of claim 27 wherein superficial anode current density is greater than 5 amperes/square inch.
- 29. A metal reduction process of electrochemically producing oxygen or carbon oxide anode product from alumina during electrolysis in a molten salt composition, comprising providing an anode having an extended surface area for the selective evolution of such product, the alumina having a solubility <1 wt. % in the molten salt composition.
- 30. A metal reduction process of electrochemically producing electrode product from metal oxide during electrolysis in a molten salt composition, comprising providing an anode having an extended surface area for the selective evolution of a gaseous electrode product, the anode comprises carbon anode, said metal oxide has a concentrated .ltoreq.2 wt. %.
- 31. A process as claimed in claim 30 wherein said carbon anode is consumed during the electrolysis.
- 32. The process of claim 30 wherein the gaseous product comprises oxygen or carbon oxide.
- 33. The process of claim 30 wherein the anode has a plurality of interior holes to increase the surface area of the anode.
- 34. The process of claim 33 wherein the holes are dimensioned to provide gas-lift pumping of the molten salt composition through the holes.
- 35. The process of claim 33 wherein the holes create a 15 to 75% void volume in the anode and extend through the anode.
- 36. The process of claim 30 wherein the extended surface area is at least about 2 times that of the superficial area of the anode.
- 37. The process of claim 30 wherein the extended surface area is at least about 30 times that of the superficial area of the anode.
- 38. The process of claim 30 wherein the salt composition comprises metal chlorides or metal fluorides, or both, in the amount of from about 0 to about 100% metal chlorides, 0 to about 100% metal fluorides, and having a liquidus temperature less than about 900.degree. C., and the electrolysis comprises deposition of molten aluminum and evolution of oxygen or carbon oxide as electrode products.
- 39. The process of claim 30 wherein the salt composition comprises lithium fluoride, magnesium fluoride and calcium fluoride which is molten at less than about 850.degree. C.
- 40. The process of claim 30 wherein the salt composition comprises sodium chloride, potassium chloride, and cryolite.
- 41. The process of claim 30 wherein the salt composition comprises about 42.75% sodium chloride, about 42.75% potassium chloride, and about 12.5% cryolite.
- 42. The process of claim 30 wherein the anode faces a cathode comprising molten metal.
- 43. The process of claim 30 wherein electrode product further comprises a metal or metal alloy.
- 44. The process of claim 30 wherein the anode is consumed during the electrolysis.
- 45. The process of claim 30 wherein the salt composition contains a fluoride.
- 46. The process of claim 45 wherein the fluoride comprises cryolite, potassium fluoride or calcium fluoride.
- 47. The process of claim 30 wherein temperature at a sidewall-molten salt interface is above the liquidus temperature of the molten salt composition, whereby there is no frozen sidewall.
- 48. The process of claim 30 wherein alumina is present as metal oxide in a concentration range 0.1 to 2%.
- 49. The process of claim 30 wherein the molten salt composition executes a circulation pattern for suspending and circulating undissolved particles of metal oxide.
- 50. The process of claim 30 wherein a molten metal cathode rests on a floor of graphitic carbon and the molten metal cathode contains alkali metal constituents.
- 51. The process of claim 30 wherein superficial anode current density is greater than 1 ampere/square inch.
- 52. The process of claim 51 wherein superficial anode current density is greater than 2 amperes/square inch.
- 53. The process of claim 52 wherein superficial anode current density is greater than 3 amperes/square inch.
- 54. The process of claim 53 wherein superficial anode current density is greater than 4 amperes/square inch.
- 55. The process of claim 54 wherein superficial anode current density is greater than 5 amperes/square inch.
- 56. A metal reduction process of electrochemically producing electrode product from a metal oxide during electrolysis in a molten salt composition, comprising providing a carbon anode spaced in a chloride-containing molten salt from a cathode, said metal oxide having a solubility <1 wt. % in said molten salt composition; the carbon anode having, relative to the cathode, an extended surface area for the evolution of carbon oxide anode product.
CROSS-REFERENCE TO RELATED APPLICATIONS
By way of international application PCT/US88/04565, this is a continuation-in-part of now-abandoned U.S. patent application Nos. 07/138,391 filed Dec. 28, 1987 and 07/197,889 filed May 24, 1988, now abandoned.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
102e Date |
371c Date |
PCT/US88/04565 |
12/19/1988 |
|
|
8/25/1989 |
8/25/1989 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO89/06289 |
7/13/1989 |
|
|
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4504366 |
Jarrett et al. |
Mar 1985 |
|
4681671 |
Duruz |
Jul 1987 |
|
4707239 |
Murphy et al. |
Nov 1987 |
|
Foreign Referenced Citations (3)
Number |
Date |
Country |
0096990 |
Dec 1983 |
EPX |
0711177 |
Jan 1980 |
SUX |
0908959 |
Feb 1982 |
SUX |
Continuation in Parts (2)
|
Number |
Date |
Country |
Parent |
138391 |
Dec 1987 |
|
Parent |
197889 |
May 1988 |
|