Stable inert anodes including an oxide of nickel, iron and aluminum
View Patent ↗Ceramic inert anodes useful for the electrolytic production of aluminum are disclosed. The inert anodes comprise oxides of Ni, Fe and Al. The Ni—Fe—Al oxide inert anode materials have sufficient electrical conductivity at operation temperatures of aluminum production cells, and also possess good mechanical stability. The Ni—Fe—Al oxide inert anodes may be used to produce commercial purity aluminum.
1. An inert anode for use in an electrolytic aluminum production cell, the inert anode comprising an electrically conductive oxide of nickel, iron and aluminum having an aluminum mole ratio Al/(Ni+Fe+Al) of up to about 0.76.
2. The inert anode of claim 1 , wherein the aluminum mole ratio Al/(Ni+Fe+Al) is from about 0.001 to about 0.713.
3. The inert anode of claim 1 , wherein the aluminum mole ratio Al/(Ni+Fe+Al) is from about 0.005 to about 0.684.
4. The inert anode of claim 1 , wherein the oxide of nickel, iron and aluminum has a nickel mole ratio Ni/(Ni+Fc+Al) of from about 0.2 to about 0.6.
5. The inert anode of claim 4 , wherein the nickel mole ratio Ni/(Ni+Fe+Al) is from about 0.25 to about 0.35.
6. The inert anode of claim 4 , wherein the nickel mole ratio Ni/(Ni+Fe+Al) is from about 0.28 to about 0.33.
7. The inert anode of claim 1 , wherein the oxide of nickel, iron and aluminum has an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.02 to about 0.8.
8. The inert anode of claim 7 , wherein the iron mole ratio Fe/(Ni+Fe+Al) is from about 0.032 to about 0.75.
9. The inert anode of claim 7 , wherein the iron mole ratio Fe/(Ni+Fe+Al) is from about 0.033 to about 0.72.
10. The inert anode of claim 1 , wherein the oxide of nickel, iron and aluminum has an aluminum mole ratio Al/(Ni+Fe+Al) of up to about 0.76, a nickel mole ratio Ni/(Ni+Fe+Al) of from about 0.2 to about 0.6, and an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.02 to about 0.8.
11. The inert anode of claim 1 , wherein the oxide of nickel, iron and aluminum has an aluminum mole ratio Al/(Ni+Fe+Al) of from about 0.001 to about 0.713, a nickel mole ratio Ni/(Ni+Fe+Al) of from about 0.25 to about 0.35, and an iron niole ratio Fef(Ni+Fe+Al) of from about 0.032 to about 0.75.
12. The inert anode of claim 1 , wherein the oxide of nickel, iron and aluminum has an aluminum mole ratio Al/(Ni+Fe+Al) of from about 0.005 to about 0.684, a nickel mole ratio Ni/(Ni+Fe+Al) of from about 0.28 to about 0.33, and an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.033 to about 0.72.
13. The inert anode of claim 1 , wherein the oxide of nickel, iron and aluminum has an electrical conductivity of at least 0.25 S/cm at a temperature between 900° C. and 1,000° C.
14. The inert anode of claim 1 , wherein the oxide of nickel, iron and aluminum has an electrical conductivity of at least 0.5 S/cm at a temperature between 900° C. and 1,000° C.
15. The inert anode of claim 1 , wherein the oxide of nickel, iron and aluminum has an electrical conductivity of at least 1 S/cm at a temperature between 900° C. and 1,000° C.
16. The inert anode of claim 1 , wherein the oxide of nickel, iron and aluminum has an electrical conductivity of at least 2 S/cm at a temperature between 900° C. and 1,000° C.
17. The inert anode of claim 1 , wherein the oxide of nickel, iron and aluminum is substantially single-phase at an operation temperature of the cell.
18. The inert anode of claim 17 , wherein the oxide of nickel, iron and aluminum is also substantially single-phase at a sintering temperature of the oxide.
19. The inert anode of claim 18 , wherein the sintering leniperature is from about 1,200 to about 1,650° C.
20. The inert anode of claim 1 , wherein the ceramic material is sintered in air.
21. The inert anode of claim 1 , wherein the oxide of nickel, iron and aluminum further includes up to about 90 weight percent of an additive.
22. The inert anode of claim 21 , wherein the additive comprises at least one material selected from Al, Co, Cr, Ga, Ge, Hf, In, Ir, Mo, Mn, Nb, Os, Re, Rh, Ru, Se, Si, Sn, Ti, V, W, Zr, Li, Ca, Ce, Y and F, and oxides thereof.
23. The inert anode of claim 1 , wherein the inert anode comprises a monolithic body of the oxide of nickel, iron and aluminum.
24. The inert anode of claim 1 , wherein the inert anode comprises a surface coated with the oxide of nickel, iron and aluminum.
25. An electrolytic aluminum production cell comprising:
a molten salt bath comprising an electrolyte and aluminum oxide;
a cathode; and
an inert anode comprising an electrically conductive oxide of nickel, iron and aluminum having an electrical conductivity of at least 0.25 S/cm at a temperature between 900° C. and 1,000° C.
26. The electrolytic aluminum production cell of claim 25 , wherein the oxide of nickel, iron and aluminum has an aluminum mole ratio Al/(Ni+Fe+Al) of up to about 0.76, a nickel mole ratio Ni/(Ni+Fe+Al) of from about 0.2 to about 0.6, and an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.02 to about 0.8.
27. The electrolytic aluminum production cell of claim 25 , wherein the oxide of nickel, iron and aluminum has an aluminum mole ratio Al/(Ni+Fe+Al) of from about 0.001 to about 0.713, a nickel mole ratio Ni/(Ni+Fe+Al) of from about 0.25 to about 0.35, and an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.032 to about 0.75.
28. The electrolytic aluminum production cell of claim 25 , wherein the oxide of nickel, iron and aluminum has an aluminum mole ratio Al/(Ni+Fe+Al) of from about 0.005 to about 0.684, a nickel mole ratio Ni/(Ni+Fe+Al) of from about 0.28 to about 0.33, and an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.033 to about 0.72.
29. The electrolytic aluminum production cell of claim 25 , wherein the oxide of nickel, iron and aluminum has at electrical conductivity of at least 0.5 S/cm at a temperature between 900° C. and 1,000° C.
30. The electrolytic aluminum production cell of claim 25 , wherein the oxide of nickel, iron and aluminum has an electrical conductivity of at least 1 S/cm at a temperature between 900° C. and 1,000° C.
31. The electrolytic aluminum production cell of claim 25 , wherein the oxide of nickel, iron and aluminum has an electrical conductivity of at least 2 S/cm at a temperature between 900° C. and 1,000° C.
32. The electrolytic aluminum production cell of claim 25 , wherein the oxide of nickel, iron and aluminum is substantially single-phase at an operation temperature of the cell.
33. The electrolytic aluniinurn production cell of claim 25 , wherein the oxide of nickel, iron and aluminum further includes up to about 90 weight percent of an additive.
34. The electrolytic aluminum production cell of claim 33 , wherein the additive comprises at least one material selected from Al, Co, Cr, Ga, Ge, Hf, In, Ir, Mo, Mn, Nb, Os, Re, Rh, Ru, Se, Si, Sn, Ti, V, W, Zr, Li, Ca, Ce, Y and F, and oxides thereof.
35. The electrolytic aluminum production cell of claim 25 , wherein the inert anode comprises a monolithic body of the oxide of nickel, iron and aluminum.
36. The electrolytic aluminum production cell of claim 25 , wherein the inert anode comprises a surface coated with the oxide of nickel, iron and aluminum.
37. A method of making an inert anode, comprising:
mixing nickel oxide, iron oxide and aluminum oxide; and
consolidating the mixture to form an electrically conductive oxide of nickel, iron and aluminum having an aluminum mole ratio Al/(Ni+Fe+Al) of up to about 0.76, a nickel mole ratio Ni/(Ni+Fe+Al) of from about 0.2 to about 0.6, and an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.02 to about 0.8.
38. The method of claim 37 , wherein the consolidating step comprises pressing the mixture and sintering the mixture.
39. The method of claim 38 , wherein the mixture is sintered at a temperature of from about 1,200 to about 1,650° C.
40. The method of claim 38 , wherein the mixture is sintered in an oxygen-containing atmosphere.
41. The method of claim 38 , wherein the mixture is sintered in air.
42. The method of claim 37 , wherein the oxide of nickel, iron and aluminum has an aluminum mole ratio Al/(Ni+Fe+Al) of from about 0.001 to about 0.713, a nickel mole ratio Ni/(Ni+Fe+Al) of front about 0.25 to about 0.35, and an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.032 to about 0.75.
43. The method of claim 37 , wherein the oxide of nickel, iron and aluminum has an aluminum mole ratio Al/(Ni+Fe+Al) of from about 0.005 to about 0.684, a nickel mole ratio Ni/(Ni+Fe+Al) of from about 0.28 to about 0.33, and an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.033 to about 0.72.
44. The method of claim 37 , wherein the oxide of nickel, iron and aluminum further includes up to about 90 weight percent of an additive.
45. The method of claim 44 , wherein the additive comprises at least one material selected from Al, Co, Cr, Ga, Ge, Hf, In, Ir, Mo, Mn, Nb, Os, Re, Rh, Ru, Se, Si, Sn, Ti, V, W, Zr, Li, Ca, Ce, Y and F, and oxides thereof.
46. The method of claim 37 , wherein the inert anode comprises a monolithic body of the oxide of nickel, iron and aluminum.
47. The method of claim 37 , wherein the inert anode comprises a surface coated with the oxide of nickel, iron and aluminum.
48. A method of producing commercial purity aluminum comprising:
passing current between an inert anode and a cathode through a bath comprising an electrolyte and aluminum oxide, wherein the inert anode comprises an oxide of nickel, iron and aluminum having an electrical conductivity of at least 0.25 S/cm at a temperature between 900° C. and 1,000° C.; and
recovering aluminum comprising a maximum of 0.2 weight percent Fe.
49. The method of claim 48 , wherein the recovered aluminum comprises loss than 0.18 weight percent Fe.
50. The method of claim 48 , wherein the recovered aluminum comprises a maximum of 0.034 weight percent Ni.
51. The method of claim 48 , wherein the recovered aluminum comprises less than 0.15 weight percent Fe, 0.034 weight percent Cu, and 0.03 weight percent Ni.
52. The method of claim 48 , wherein the recovered aluminum comprises a maximum of 0.13 weight percent Fe, 0.03 weight percent Cu, and 0.03 weight percent Ni.
53. The method of claim 48 , wherein the oxide of nickel, iron and aluminum has an aluminum mole ratio Al/(Ni+Fe+Al) of up to about 0.76, a nickel mole ratio Ni/(Ni+Fe+Al) of from about 0.2 to about 0.6, and an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.02 to about 0.8.
54. The method of claim 48 , wherein the oxide of nickel, iron and aluminum has an aluminum mole ratio Al/(Ni+Fe+Al) of from about 0.001 to about 0.713, a nickel mole ratio Ni/(Ni+Fe+Al) of from about 0.25 to about 0.35, and an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.032 to about 0.75.
55. The method of claim 48 , wherein the oxide of nickel, iron and aluminum has an aluminum mole ratio Al/(Ni+Fe+Al) of from about 0.005 to about 0.684, a nickel mole ratio Ni/(Ni+Fe+Al) of from about 0.28 to about 0.33, and an iron mole ratio Fe/(Ni+Fe+Al) of from about 0.033 to about 0.72.
56. The method of claim 48 , wherein the oxide of nickel, iron and aluminum further includes up to about 90 weight percent of an additive.
57. The method of claim 56 , wherein the additive comprises at least one material selected from Al, Co, Cr, Ga, Ge, Hf, In, Ir, Mo, Mn, Nb, Os, Re, Rh, Ru, Se, Si, Sn, Ti, V, W, Zr, Li, Ca, Ce, Y and F, and oxides thereof.
58. The method of claim 48 , wherein the inert anode comprises a monolithic body of the oxide of nickel, iron and aluminum.
59. The method of claim 48 , wherein the inert anode comprises a surface coated wit the oxide of nickel, iron and aluminum.