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EP-4741536-A1 - METHOD FOR PRODUCING ALUMINUM

EP4741536A1EP 4741536 A1EP4741536 A1EP 4741536A1EP-4741536-A1

Abstract

This method for producing aluminum is for obtaining, from an aluminum alloy material, aluminum having higher purity than said aluminum material, the method being characterized by: immersing, in an electrolytic solution (11), a cathode electrode (9) ad an anode electrode (7) including an aluminum alloy material containing 0.1 - 24 mass% of Si; causing a current to flow at a current density of 0.1 - 25 mA/cm 2 on the surface of the anode electrode (7) where the electrolytic solution (11) and the aluminum alloy material come in contact with each other; and depositing aluminum on the cathode electrode.

Inventors

  • MATSUDA, JUNICHI
  • KANEHARA, Yuto

Assignees

  • Proterial, Ltd.

Dates

Publication Date
20260513
Application Date
20241217

Claims (10)

  1. A method for producing aluminum from an aluminum raw material, in which aluminum with higher purity than the aluminum raw material can be obtained, the method comprising: immersing an anode electrode, which includes the aluminum raw material containing 0.1 mass% or more and 24 mass% or less of Si, and a cathode electrode in an electrolytic solution; and applying a current to flow at a current density of 0.1 mA/cm 2 or more and 25 mA/cm 2 or less on a surface of the anode electrode where the aluminum raw material comes into contact with the electrolytic solution, thereby depositing aluminum on the cathode electrode.
  2. The method for producing aluminum according to claim 1, wherein the aluminum raw material of the anode electrode further contains 0.1 mass% or more and 5 mass% or less of Cu.
  3. The method for producing aluminum according to claim 1, wherein the aluminum raw material of the anode electrode further contains 0.15 mass% or more and 1.8 mass% or less of Fe.
  4. The method for producing aluminum according to claim 1, wherein the current is applied to the anode electrode while stirring the electrolytic solution around the anode electrode.
  5. The method for producing aluminum according to claim 1, wherein a surface area of a portion of the anode electrode where the aluminum material is in contact with the electrolytic solution is made larger than a surface area of a portion of the cathode electrode that is in contact with the electrolytic solution.
  6. The method for producing aluminum according to claim 1, wherein the electrolytic solution includes dialkyl sulfone and aluminum halide.
  7. The method for producing aluminum according to claim 6, wherein a molar ratio of the dialkyl sulfone to the aluminum halide in the electrolytic solution is 1.5 mol or more and 5 mol or less of the aluminum halide per 10 mol of the dialkyl sulfone.
  8. The method for producing aluminum according to claim 7, wherein the electrolytic solution further includes at least one nitrogen-containing compound selected from a group consisting of ammonium halide, a hydrogen halide salt of primary amine, a hydrogen halide salt of secondary amine, a hydrogen halide salt of tertiary amine, and a quaternary ammonium salt represented by a general formula of R 1 R 2 R 3 R 4 N•X where R 1 to R 4 are the same or different alkyl groups and X is a counter anion for a quaternary ammonium cation.
  9. The method for producing aluminum according to claim 1, wherein while the electric current is flowing through the anode electrode, the aluminum is deposited on the cathode electrode such that an arithmetic mean height Sa of the anode electrode is 2.3 µm or more and 10 µm or less.
  10. The method for producing aluminum according to any one of claims 1 to 9, wherein the current density is 0.1 mA/cm 2 or more and 20 mA/cm 2 or less.

Description

TECHNICAL FIELD The present invention relates to a method for producing aluminum in which aluminum with higher purity can be obtained from, for example, a casting alloy or the like. BACKGROUND OF THE INVENTION Unlike iron and steel materials, widely used aluminum cannot be smelted from raw ore using thermal reduction reaction with carbon, and thus it is generally necessary to use electricity in the smelting processes, such as in Bayer process or Hall-Héroult process. For this reason, production of virgin aluminum metal emits a large amount of carbon dioxide, imposing heavy burden on environment. Thus, it is preferable to reuse used aluminum products through recycling. For example, attempts have been made to easily produce highly purified aluminum material from aluminum alloy scrap (Patent Document 1, for example). PRIOR ART [Patent Document 1] International Patent Publication No. 2020/196013(WO2020/196013) SUMMARY OF THE INVENTION (PROBLEMS TO BE SOLVED BY THE INVENTION) The term "aluminum" includes a wide variety of alloys that are used depending on applications. For example, in a case of aluminum cans, A3000 series (Al-Mn series) wrought materials are used, and there is no problem if such materials are directly recycled back into aluminum cans. However, when converting such materials into other alloys, components thereof may cause a problem. In such the case, it is required to reduce an amount of the recycled alloy and to mix a certain amount of virgin metal. For this reason, recycling into the same alloy series is most efficient. However, although there has been a large amount of scrap of aluminum alloys that have been used for automobile engine parts etc., the amount of reused aluminum alloys is in decline due to widespread use of electric vehicles and the like in the recent years. This makes it difficult to reuse the aluminum alloys within the same field. In particular, metals in the above field are often cast products (castings, die-castings) containing more alloy components than wrought materials, which makes it difficult to be converted into products in other fields. For example, an AC2A alloy (JIS) used as a casting material contains 4.0 mass% or more and 6.0 mass% or less of silicon (Si) and the content of Si and the like is much higher compared to the wrought materials. This makes it extremely difficult to reuse such the alloy for other wrought material applications. The present invention was made in view of such problems. It is an object of the present invention to provide a method for producing aluminum, in which aluminum base metal or a used aluminum alloy, particularly an aluminum alloy with high Si content, is used as aluminum raw material such that aluminum having higher purity than the aluminum raw material can be produced. (MEANS FOR SOLVING PROBLEMS) To achieve the above object, an aspect of the present invention is a method for producing aluminum from an aluminum raw material, in which aluminum with higher purity than the aluminum raw material can be obtained. The method includes immersing an anode electrode, which includes the aluminum raw material containing 0.1 mass% or more and 24 mass% or less of Si, and a cathode electrode in an electrolytic solution, and applying a current to flow at a current density of 0.1 mA/cm2 or more and 25 mA/cm2 or less on a surface of the anode electrode where the aluminum raw material comes into contact with the electrolytic solution, thereby depositing aluminum on the cathode electrode. The aluminum raw material of the anode electrode may further contain 0.1 mass% or more and 5 mass% or more of copper (Cu). The aluminum raw material of the anode electrode may further contain 0.15 mass% or more and 1.8 mass% or less of iron (Fe). It is preferable to apply the current to the anode electrode while stirring the electrolytic solution around the anode electrode. It is preferable to make a surface area of a portion of the anode electrode where the aluminum raw material is in contact with the electrolytic solution larger than a surface area of a portion of the cathode electrode that is in contact with the electrolytic solution. It is preferable that the electrolytic solution includes dialkyl sulfone and aluminum halide. It is preferable that a molar ratio of the dialkyl sulfone to the aluminum halide in the electrolytic solution is 1.5 mol or more and 5 mol or less of the aluminum halide per 10 mol of the dialkyl sulfone. It is preferable that the electrolytic solution further includes at least one nitrogen-containing compound selected from a group consisting of ammonium halide, a hydrogen halide salt of primary amine, a hydrogen halide salt of secondary amine, a hydrogen halide salt of tertiary amine, and a quaternary ammonium salt represented by a general formula of R1R2R3R4N•X where R1 to R4 are the same or different alkyl groups and X is a counter anion for a quaternary ammonium cation. It is preferable that, while the current is flowing through the anode