Systems and methods for purifying aluminum

Patent metadata

Field	Value
Publication number	US-10407786-B2
Application number	US-201615041899-A
Country	US
Kind code	B2
Filing date	Feb 11, 2016
Priority date	Feb 11, 2015
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

The application is directed towards methods for purifying an aluminum feedstock material. A method provides: (a) feeding an aluminum feedstock into a cell (b) directing an electric current into an anode through an electrolyte and into a cathode, wherein the anode comprises an elongate vertical anode, and wherein the cathode comprises an elongate vertical cathode, wherein the anode and cathode are configured to extend into the electrolyte zone, such that within the electrolyte zone the anode and cathode are configured with an anode-cathode overlap and an anode-cathode distance; and producing some purified aluminum product from the aluminum feedstock.

First claim

What is claimed is:

1. A method comprising:
(a) feeding an aluminum feedstock into a cell access channel of an aluminum electrolysis cell, wherein the aluminum electrolysis cell comprises a molten metal pad zone and an electrolyte zone, and wherein the feeding comprises providing the aluminum feedstock to the molten metal pad zone;
(b) directing an electric current into an anode through an electrolyte and into a cathode, wherein the anode comprises a solid elongate vertical anode, and wherein the cathode comprises an elongate vertical cathode, wherein both the anode and the cathode are in fluid communication with the electrolyte zone, wherein the anode and cathode extend into the electrolyte zone such that, within the electrolyte zone, the anode and cathode realize an anode-cathode overlap and an anode-cathode distance;
(c) wetting at least a portion of a surface of the solid elongate vertical anode with a molten material from the molten metal pad zone, wherein the molten material comprises aluminum metal;
(d) concomitant with directing the electric current, producing at least some aluminum ions in the electrolyte zone via the aluminum metal on the surface of the solid elongate vertical anode; and
(e) concomitant with directing the electric current step, reducing at least some of the aluminum ions in the electrolyte zone at a surface of the elongate vertical cathode, thereby producing a purified aluminum product;

wherein the solid elongate vertical anode is in direct fluid communication with the electrolyte zone via a thin layer of the aluminum metal located on at least a portion of the surface of the solid elongate vertical anode.

2. The method of claim 1 , comprising:
prior to feeding the aluminum feedstock, melting the feedstock material.

3. The method of claim 1 , comprising:
collecting at least some of the purified aluminum product.

4. The method of claim 1 , comprising:
removing the purified aluminum product from the aluminum electrolysis cell.

5. The method of claim 4 , wherein removing the purified aluminum product comprises tapping the aluminum electrolysis cell.

6. The method of claim 4 , wherein the removing step comprises:
casting the purified aluminum product into an ingot, wherein the ingot comprises an aluminum product having an aluminum purity of at least 99.5 wt. %.

7. The method of claim 1 , wherein the method comprises: removing at least one of: sludge and raffinate from the molten metal pad zone via the cell access channel.

8. The method of claim 1 , wherein both the anode and the cathode comprise an aluminum-wettable material.

9. The method of claim 1 , wherein directing the electric current comprises supplying the electric current to the solid elongate vertical anode.

10. The method of claim 1 , wherein both the anode and the cathode are submerged in the electrolyte.

11. The method of claim 1 , wherein the purified aluminum product comprises an aluminum purity of from 99.5 wt. % to 99.999 wt. % Al.

12. The method of claim 1 , wherein the purified aluminum product comprises an aluminum purity of from 99.8 wt. % to 99.999 wt. % Al.

13. The method of claim 1 , wherein the purified aluminum product comprises an aluminum purity of from 99.9 wt. % to 99.999 wt. % Al.

14. The method of claim 1 , wherein the purified aluminum product comprises an aluminum purity of from 99.98 wt. % to 99.999 wt. % Al.

15. The method of claim 1 , comprising:
forming a third zone, wherein the third zone comprises a purified aluminum product, wherein the third zone is located above the electrolyte zone.

16. The method of claim 15 , wherein the third zone is a top layer.

17. The method of claim 1 , comprising:
casting the purified aluminum product into a cast form.

18. The method of claim 1 , wherein the purified aluminum product is produced via the aluminum electrolysis cell at an energy efficiency of from 12 to 15 kWh/kg of purified aluminum product.

19. The method of claim 1 , wherein the purified aluminum is produced via the aluminum electrolysis cell at an energy efficiency of from 2 to 10 kWh/kg of purified aluminum product.

20. The method of claim 1 , wherein the purified aluminum product is produced via the aluminum electrolysis cell at an energy efficiency of from 2 to 6 kWh/kg of purified aluminum.

21. The method of claim 1 , wherein the aluminum electrolysis cell comprises a cell chamber, the method comprising: purging a cell chamber with an inert gas.

22. The method of claim 1 , comprising:
producing an inert headspace within the aluminum electrolysis cell, wherein the producing comprises flowing an inert gas into the aluminum electrolysis cell via an inert gas inlet, wherein the inert gas inlet is located in a refractory top cover of the aluminum electrolysis cell.

23. The method of claim 1 , comprising:
adding bath components to the aluminum electrolysis cell via the cell access channel.

24. The method of claim 1 , comprising:
adding bath components to the aluminum electrolysis cell via the cell access channel.

25. The method of claim 24 , wherein the bath components supplement the electrolyte and promote producing at least some aluminum ions in the electrolyte zone and promote reducing at least some of the aluminum ions in the electrolyte zone.

26. The method of claim 1 , wherein the solid elongate vertical anode comprises at least one of TiB 2 , ZrB 2 , HfB 2 , SrB 2 , carbonaceous material, W, Mo, steel and combinations thereof; and wherein the elongate vertical cathode comprises at least one of TiB 2 , ZrB 2 , HfB 2 , SrB 2 , carbonaceous material, and combinations thereof.

Assignees

• Alcoa Usa Corp

Inventors

• Deyoung David H
• Liu Xinghua
• Mydland Brent L
• Wiswall James

Classifications

• C25C3/08 Primary

  Cell construction, e.g. bottoms, walls, cathodes · CPC title

• C25C3/18

  Electrolytes · CPC title

• C25C3/125

  based on carbon · CPC title

• C25C3/24 Primary

  Refining · CPC title

• C25C3/14

  Devices for feeding or crust breaking · CPC title