Method for producing metallic aluminum and polysilicon with high-silicon aluminum-containing resource

Patent metadata

Field	Value
Publication number	US-2024247391-A1
Application number	US-202218289876-A
Country	US
Kind code	A1
Filing date	Apr 21, 2022
Priority date	May 8, 2021
Publication date	Jul 25, 2024
Grant date	—

Abstract

The present application belongs to the technical field of aluminum metallurgy, and specifically relates to a method for producing metallic aluminum and polysilicon with a high-silicon aluminum-containing resource. The method includes: pretreating the high-silicon aluminum-containing resource to obtain an aluminum-silicon oxide material; the aluminum-silicon oxide material is used to produce a metallic aluminum product and a copper-aluminum-silicon alloy with silicon enriched by molten salt electrolysis in a double-chamber electrolytic cell; and the copper-aluminum-silicon alloy is used to produce an aluminum-silicon alloy and/or polysilicon by molten salt electrolysis in a single-chamber electrolytic cell, and further separating the aluminum-silicon alloy by physical methods to obtain polysilicon. The present application has characteristics such as low production cost, continuous electrolysis operations, high product quality, and environmental friendliness.

First claim

1 . A method for producing metallic aluminum and polysilicon with a high-silicon aluminum-containing resource, comprising the following steps:
step (1): pretreating the high-silicon aluminum-containing resource to obtain an aluminum-silicon oxide material; step (2): with the aluminum-silicon oxide material as an electrolysis raw material, conducting molten salt electrolysis in a double-chamber electrolytic cell to prepare metallic aluminum and a copper-aluminum-silicon alloy, wherein the double-chamber electrolytic cell is divided into an anode chamber and a cathode chamber to physically separate an anode electrolyte from a cathode electrolyte; the anode chamber is provided with an anode, and the cathode chamber is provided with a cathode; a copper-aluminum alloy is accommodated at a bottom of the double-chamber electrolytic cell, and the copper-aluminum alloy is in contact with each of the anode electrolyte and the cathode electrolyte; and under energized operation conditions, the aluminum-silicon oxide material is fed into the anode chamber, such that the metallic aluminum is produced in the cathode chamber and the copper-aluminum alloy at the bottom of the double-chamber electrolytic cell is transformed into the copper-aluminum-silicon alloy; and step (3): taking the copper-aluminum-silicon alloy out, placing the copper-aluminum-silicon alloy in a single-chamber electrolytic cell, and conducting molten salt electrolysis to prepare an aluminum-silicon alloy and/or polysilicon, wherein in the single-chamber electrolytic cell, a bottom melt is a copper-aluminum-silicon alloy anode, a middle melt is a refining electrolyte, and an upper melt is an aluminum melt cathode; and under energized operation conditions, Al and Si in the copper-aluminum-silicon alloy are oxidized, enter the refining electrolyte, and then are reduced at the aluminum melt cathode to obtain the aluminum-silicon alloy and/or the polysilicon.

2 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (1), a Al 2 O 3 /SiO 2 mass ratio in the high-silicon aluminum-containing resource is 1:(0.5-7), and the high-silicon aluminum-containing resource comprises one or more selected from the group consisting of high-silicon bauxite, fly ash, coal gangue, kaolin, and alunite.

3 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (2), the anode is a carbon anode or an inert anode.

4 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (2), the anode electrolyte is a fluoride system or a chloride system, and
the fluoride system comprises 60 wt % to 90 wt % of a cryolite, 5 wt % to 25 wt % of AlF 3 , 1 wt % to 5 wt % of Al 2 O 3 , and 0 wt % to 15 wt % of an additive, wherein the cryolite is one or more selected from the group consisting of Na 3 AlF 6 , Li 3 AlF 6 , and K 3 AlF 6 and the additive is one or more selected from the group consisting of LiF, NaF, KF, CaF 2 , MgF 2 , and BaF 2 .

5 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (2), the cathode electrolyte comprises 20 wt % to 70 wt % of a weighting agent, 15 wt % to 50 wt % of AlF 3 , 13 wt % to 40 wt % of NaF, and 20 wt % or less of an additive, wherein the weighting agent is BaCl 2 and/or BaF 2 and the additive is one or more selected from the group consisting of LiF, Li 3 AlF 6 , Na 3 AlF 6 , CaF 2 , MgF 2 , NaCl, LiCl, CaCl 2 , and MgCl 2 .

6 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (2), a Al content in the copper-aluminum alloy is 55 at % to 80 at %.

7 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (3), the refining electrolyte comprises 20 wt % to 40 wt % of BaF 2 , 40 wt % to 70 wt % of cryolite, 5 wt % to 25 wt % of AlF 3 , 0 wt % to 10 wt % of a fluorine-silicon compound, and 0 wt % to 15 wt % of an additive, wherein the cryolite is one or more selected from the group consisting of Na 3 AlF 6 , Li 3 AlF 6 , and K 3 AlF 6 , the fluorine-silicon compound is one or more selected from the group consisting of Na 2 SiF 6 , K 2 SiF 6 , Li 2 SiF 6 , and SiF 4 , and the additive is one or more selected from the group consisting of LiF, NaF, KF, CaF 2 , and MgF 2 .

8 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (3), the aluminum melt cathode is a pure metallic aluminum melt or a silicon-containing metallic aluminum melt.

9 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein
in step (2), when the double-chamber electrolytic cell works normally, an anode current density is 0.1 A/cm 2 to 1.5 A/cm 2 and a temperature is 800° C. to 1,000° C.

10 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (3), the aluminum-silicon alloy is used to produce polysilicon by a physical method and/or a chemical method, wherein the physical method comprises one or more selected from the group consisting of a liquation method, a segregation in solidification process, a vacuum distillation method, and a directional solidification method, and the chemical method comprises an acid pickling method and an electrorefining method.

11 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (1), in the aluminum-silicon oxide material, a total content of Al 2 O 3 and SiO 2 is higher than or equal to 90.0%, a content of Al 2 O 3 is higher than or equal to 40.0%, and a content of SiO 2 is higher than or equal to 0.1%.

12 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (2), the cathode is one or a composite of two or more selected from the group consisting of graphite, aluminum, and TiB 2 /C.

13 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (2), the anode electrolyte is a chloride system, and the chloride system is CaCl 2 or comprises CaCl 2 and one or more selected from the group consisting of NaCl, KCl, BaCl 2 , CaF 2 , LiCl, and CaO.

14 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (2), the cathode electrolyte comprises 20 wt % to 40 wt % of BaF 2 , 15 wt % to 50 wt % of AlF 3 , 20 wt % to 40 wt % of NaF, and 10 wt % to 20 wt % of CaF 2 or the cathode electrolyte comprises 50 wt % to 65 wt % of BaCl 2 , 15 wt % to 30 wt % of AlF 3 , 13 wt % to 30 wt % of NaF, and 0 wt % to 5 wt % of NaCl.

15 . The method for producing the metallic aluminum and polysilicon with the high-silicon aluminum-containing resource according to claim 1 , wherein in step (2), and the copper-aluminum alloy remains a liquid during a normal electrolytic work, and a density of the copper-aluminum alloy is greater

Assignees

• Univ Zhengzhou

Inventors

• Zhao Zhongwei

Classifications

• C25C3/18

  Electrolytes · CPC title

• C25B9/09

  Fused bath cells · CPC title

• C25C7/025

  used in cells for the electrolysis of melts · CPC title

• C25C7/04

  Diaphragms; Spacing elements · CPC title

• C25B1/33

  Silicon · CPC title