PURIFICATION OF ALUMINIUM

• US 3,650,730 A
• Filed: 03/21/1969
• Issued: 03/21/1972
• Est. Priority Date: 03/21/1968
• Status: Expired due to Term

• Current Assignee: Administrator Derham, Deceased Derham
• Original Assignee: Administrator Derham, Deceased Derham
• Inventors: Derham, deceased, Derham, administrator
• Primary Examiner(s): Rutledge, L. Dewayne
• Assistant Examiner(s): White, G. K.
• Application Number:
  US04/810,086
• Time in Patent Office: 1,096 Days
• Field of Search: 75/68,93,94
• US Class Current: 75/678
• CPC Class Codes: C22B 21/064 using inert or reactive gases C22B21/066 and C22B21/068 take precedence

Abstract

A process for removing impurities from aluminum or aluminum alloys comprising treating the molten metal with a chloridizing agent while the metal is covered with a layer of molten flux, so as to suppress the emission of fumes from the molten metal. An improved aspect of such process wherein the flux contains at least part of the chloridizing agent.

Claims

2. The process as set forth in claim 1 wherein the molten aluminum is initially covered with a molten flux layer of sodium chloride.

3. The process as set forth in claim 1 wherein the molten aluminum is initially covered with a molten flux layer of potassium chloride.

4. The process as set forth in claim 1 wherein the molten aluminum is initially covered with a molten flux layer of a mixture of sodium chloride and potassium chloride.

5. The process as set forth in claim 1 in which said aluminum contains magnesium as an impurity and wherein the feed rate of the chlorine containing vapor is maintained to react with the magnesium and form magnesium chloride and wherein the resulting magnesium chloride is absorbed by said flux layer.

6. In a process for removing impurities from molten aluminum by treatment with a chloridizing agent wherEin the improvement comprises a. forming a flux by fusing at least one salt selected from the group consisting of alkali metal chlorides, alkaline-earth metal chlorides, ammonium chloride, alkali metal fluorides, alkaline-earth metal fluorides and ammonium fluoride, with at least one salt selected from the group consisting of aluminum chloride and aluminum fluoride to form an aluminum halide double salt and including in said flux at least one single salt selected from the group consisting of alkali metal chlorides, alkaline-earth metal chlorides, ammonium chloride, alkali metal fluorides, alkaline-earth metal fluorides and ammonium fluoride, b. covering said molten aluminum with said flux as a molten layer, and c. utilizing the double halide salt portion of said molten flux layer as the chloridizing agent in said process.

7. The process as set forth in claim 6 wherein the molten aluminum is covered with a molten flux layer containing sodium aluminum chloride and a single salt selected from the group consisting of sodium chloride and potassium chloride.

8. The process as set forth in claim 6 wherein the molten aluminum is covered with a molten flux layer containing potassium aluminum chloride and a single salt selected from the group of sodium chloride and potassium chloride.

9. The process as set forth in claim 6 including the additional step of providing at least a portion of the quantity of chloridizing agent required to remove said impurities from said aluminum by introducing a chlorine containing vapor into the molten aluminum.

10. In a process for removing impurities from molten aluminum by treatment with a chloridizing agent wherein the improvement comprises covering the molten aluminum with a molten flux layer comprising an aluminum chloride double salt and at least one single salt selected from the group consisting of alkali metal chlorides, alkaline-earth metal chlorides, ammonium chloride, alkali metal fluorides, alkaline-earth metal fluorides and ammonium fluoride to suppress the emission of fumes caused by the treatment with said chloridizing agent.

11. A process as defined in claim 10 wherein said flux contains at least a portion of the quantity of chloridizing agent required to remove said impurities from said aluminum.

12. A process as defined in claim 11 further comprising providing at least a portion of the quantity of chloridizing agent required to remove said impurities from said aluminum by introducing a reactive chlorine-containing vapor into the molten aluminum.

13. A process as defined in claim 12 in which the molten aluminum contains magnesium as an impurity.

14. A process as defined in claim 10 in which the double salt portion of said flux is a double salt of AlCl3 and a member selected from the group consisting of alkali metal chlorides, alkaline-earth metal chlorides and ammonium chloride.

15. A process as defined in claim 10 wherein said double salt portion of said flux is selected from a member of the group consisting of Na3AlCl6, NaAlCl4, KAlCL4, LiAlCl4, MgCl2.2AlCl3 and NH4AlCl4.