Method for producing metal aluminum by molten salt electrolysis of aluminum oxide

Patent metadata

Field	Value
Publication number	US-2024141529-A1
Application number	US-202218288406-A
Country	US
Kind code	A1
Filing date	Apr 25, 2022
Priority date	May 8, 2021
Publication date	May 2, 2024
Grant date	—

Abstract

A method for producing metal aluminum by molten salt electrolysis of aluminum oxide is provided. The method for producing metal aluminum by molten salt electrolysis of aluminum oxide uses an electrolytic cell. The electrolytic cell is divided into an anode chamber and a cathode chamber, and is filled with melts such as anolyte, catholyte and an alloy medium. The electrolytic cell is powered on to operate and an aluminum oxide raw material is added to the anode chamber to obtain high-purity metal aluminum in the cathode chamber. The disclosure provides an aluminum electrolysis method having the advantages of strong electrolysis operation adaptability, large selectivity of electrolysis materials and raw materials, being energy saving and environmentally friendly, and being capable of directly producing refined aluminum or high-purity aluminum.

First claim

What is claimed is:

1 . A method for producing metal aluminum by a molten salt electrolysis of aluminum oxide, comprising:
using an electrolytic cell divided into an anode chamber and a cathode chamber, after the electrolytic cell is powered on to operate, adding an aluminum oxide raw material to the anode chamber to obtain a metal aluminum product in the cathode chamber, wherein the anode chamber and the cathode chamber are configured to physically separate an anolyte from a catholyte, the anode chamber is provided with an anode, and the cathode chamber is provided with a cathode; and a bottom of the electrolytic cell is filled with an alloy medium, and the alloy medium respectively contacts the anolyte and the catholyte and is configured to form electrochemical reaction interfaces of aluminum ions/aluminum atoms and serve as a transfer medium of the aluminum atoms.

2 . (canceled)

3 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 1 , wherein the anolyte is a fluoride system containing 60 to 90 wt % of cryolite, 5 to 30 wt % of AlF 3 , 1 to 10 wt % of Al 2 O 3 , and 0 to 15 wt % of an additive; and the cryolite is one or more of Na 3 AlF 6 , Li 3 AlF 6 , and K 3 AlF 6 , and the additive is one or more of LiF, NaF, KF, CaF 2 , MgF 2 , BaF 2 , and NaCl.

4 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 1 , wherein the anolyte is a chloride system; and the chloride system is CaCl 2 ), or the chloride system comprises CaCl 2 ) and one or more of NaCl, KCl, BaCl 2 , CaF 2 , LiCl, and CaO and a mole percentage of the CaCl 2 ) in the chloride system is not lower than 50%.

5 . (canceled)

6 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 1 , wherein the catholyte is a pure fluoride system containing 20 to 40 wt % of BaF 2 , 30 to 50 wt % of AlF 3 , 15 to 40 wt % of NaF, and 0 to 20 wt % of an additive; and the additive is one or more of CaF 2 , LiF, Li 3 AlF 6 , and MgF 2 .

7 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 1 , wherein the catholyte is a fluoride-chloride system containing 50 to 70 wt % of BaCl 2 , 15 to 30 wt % of AlF 3 , 10 to 30 wt % of NaF, and 0 to 15 wt % of an additive; and the additive is one or more of LiF, Li 3 AlF 6 , CaF 2 , MgF 2 , NaCl, LiCl, CaCl 2 , and MgCl 2 .

8 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 1 , wherein the anode is a carbon anode or an inert anode.

9 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 1 , wherein the cathode is one or a composite of graphite, aluminum, and an inert wettable cathode material.

10 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 1 , wherein the alloy medium is an alloy formed by Al and one or more of Cu, Sn, Zn, Ga, In, Bi, and Sb; and
the alloy medium remains a liquid state during a normal electrolysis and has a density greater than a density of the anolyte or a density of the catholyte.

11 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 10 , wherein the alloy medium is an Al—Cu alloy, and an Al content in the alloy medium is 40 to 75 wt %.

12 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 3 , wherein the alloy medium is an alloy formed by Al and one or more of Cu, Sn, Zn, Ga, In, Bi, and Sb; and
the alloy medium remains a liquid state during a normal electrolysis and has a density greater than a density of the anolyte or a density of the catholyte.

13 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 4 , wherein the alloy medium is an alloy formed by Al and one or more of Cu, Sn, Zn, Ga, In, Bi, and Sb; and
the alloy medium remains a liquid state during a normal electrolysis and has a density greater than a density of the anolyte or a density of the catholyte.

14 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 6 , and the alloy medium is an alloy formed by Al and one or more of Cu, Sn, Zn, Ga, In, Bi, and Sb; and
the alloy medium remains a liquid state during a normal electrolysis and has a density greater than a density of the anolyte or a density of the catholyte.

15 . The method for producing the metal aluminum by the molten salt electrolysis of the aluminum oxide according to claim 7 , and the alloy medium is an alloy formed by Al and one or more of Cu, Sn, Zn, Ga, In, Bi, and Sb; and
the alloy medium remains a liquid state during a normal electrolysis and has a density greater than a density of the anolyte or a density of the catholyte.

Assignees

• Univ Central South

Inventors

• Zhao Zhongwei
• Sun Fenglong
• Lei Yuntao

Classifications

• C25C3/18 Primary

  Electrolytes · CPC title

• C22C9/01

  with aluminium as the next major constituent · CPC title

• C22C13/00

  Alloys based on tin · CPC title

• C22C21/12

  with copper as the next major constituent · CPC title

• C22C21/18

  with zinc · CPC title