PURIFICATION OF ALUMINUM WITH TURBINE BLADE AGITATION

• US 3,839,019 A
• Filed: 08/16/1973
• Issued: 10/01/1974
• Est. Priority Date: 09/18/1972
• Status: Expired due to Term

• Current Assignee: Burl L. Slaugenhaupt, Marshall J. Bruno, Noel Jarrett, Robert E. Graziano
• Original Assignee: Burl L. Slaugenhaupt, Marshall J. Bruno, Noel Jarrett, Robert E. Graziano
• Inventors: Bruno, Marshall J., Jarrett, Noel, Slaugenhaupt, Burl L., Graziano, Robert E.
• Primary Examiner(s): Rutledge, L. Dewayne
• Assistant Examiner(s): Andrews, M. J.
• Application Number:
  US05/388,806
• Time in Patent Office: 411 Days
• Field of Search: 75/68R 266/34A
• US Class Current: 75/681
• CPC Class Codes: C22B 21/064 using inert or reactive gases C22B21/066 and C22B21/068 take precedence
• CPC Class Codes: C22B 21/066 Treatment of circulating aluminium, e.g. by filtration C22B21/068 takes precedence

Abstract

Aluminum is purified by chloridizing a molten body of aluminum in a highly efficient manner. High metal chloridization rates are achieved in a system wherein chlorine utilization efficiency is 100 percent or very closely approaches this level. The system includes a chlorine-metal contacting technique which includes an agitator and which controls and maintains contacting conditions to optimize efficiency.

Claims

1. CONTACTING WITHIN A CHLORIDIZATION CHAMBER SAID MOLTEN ALUMINUM WITH A GAS COMPRISING A REACTIVE CHLORINACEOUS GAS INTRODUCED AT A SITE SUBSTANTIALLY 10 INCHES OR MORE BELOW THE UPPER SURFACE OF THE MOLTEN ALUMINUM BEING TREATED TO REACT CHLORINE WITH METALLIC IMPURITIES IN SAID ALUMINUM AND PRODUCED THE CHLORINE SALTS OF SAID IMPURITY METALS,

2. maintaining at the region of said chlorinaceous gas introduction agitation conditions which produce in the melt a substantially uniform distribution of small gas bubbles which prevails substantially throughout the molten aluminum in said chloridization chamber while substantially avoiding any fragmentation or shattering of the molten metal so as to substantially avoid emulsification of molten aluminum and chloride salt phases.

3. The process according to claim 1 wherein said chlorinaceous gas is chlorine.

4. The process according to claim 3 wherein the agitation means is a turbine impeller and the chlorine is introduced at the center of rotation of said turbine which turbine is positioned within 2 inches of the bottom of said chloridization chamber.

5. The method according to claim 1 wherein the molten metal is passed through multiple chloridization chambers followed by at least one settling chamber to facilitate separation of molten metal from any occluded salt.

6. The continuous method of treating molten aluminum containing at least one metallic impurity selected from the group consisting of magnesium, sodium and calcium, comprising the steps:

7. The method according to claim 1 wherein impurity metal chloride salt reaction product is removed from said chloridization chamber to prevent an excessive build-up of salt so as to maintain said 10 inch minimum metal depth above said chlorinaceous gas introduction site.

8. The methOd according to claim 1 wherein said chlorinaceous gas is provided in an amount stoichiometrically related to the amount of said impurities to be removed.

9. The method according to claim 1 wherein said gas also comprises a non-reactive gas in addition to said chlorinaceous gas.

10. The method according to claim 9 wherein said amount of gas introduced is at least 0.005 SCF per pound of molten aluminum treated.

11. The method according to claim 9 wherein the relative amount of chlorinaceous gas is small in comparison to the non-reactive gas.

12. The method according to claim 9 wherein the chlorinaceous gas is chlorine and the non-reactive gas is selected from argon or nitrogen or mixtures thereof and the amount of chlorine is relatively small in comparison with the non-reactive gas.

13. The process of purifying molten aluminum comprising:

14. A method according to claim 13 wherein said agitation conditions maintained are such as are derivable from a turbine blade 12 inches in outside diameter having 12 paddles of about 2 inches by 2 inches and rotating at a speed of from 150 to 400 rpm.

15. The method according to claim 14 wherein the rotation speed of said turbine blade is from 150 to 275 rpm.

16. The method according to claim 13 wherein the agitation conditions are produced by a multiple bladed impeller rotating at a peripheral speed of 8 to 20 feet per second.

17. The method according to claim 16 wherein the said gas flux is introduced to the central portions of the agitation zone of said impeller.

18. The method according to claim 13 wherein the agitation conditions are produced by a multiple bladed impeller rotating at a peripheral speed of 8 to 14 feet per second.

19. The method according to claim 14 wherein the ratio of the smaller dimension across the body of the molten metal in inches to the diameter of impeller in inches is between 1.5 and 2:

1.

20. The method according to claim 13 wherein said agitation conditions are effected by a rotating vaned impeller operated so as to be equivalent to a turbine blade 12 inches in outside diameter having 12 paddles of about 2 inches by 2 inches and rotating at a speed of from 150 to 400 rpm and the ratio of the smaller dimension across the body of the molten metal in inches to the diameter of impeller in inches is between 1.5 and 2:

1.

21. The method according to claim 13 wherein said gas also comprises a non-reactive gas in addition to said chlorinaceous gas.

22. The method according to claim 13 wherein said amount of gas introduced is at least 0.005 SCF per pound of molten aluminum treated.

23. The method according to claim 21 wherein the relative amount of chlorinaceous gas is small in comparison to the non-reactive gas.

24. The method according to claim 13 wherein the chlorinaceous gas is chlorine and the non-reactive gas is selected from argon or nitrogen or mixtures thereof and the amount of chlorine is relatively small in comparison with the non-reactive gas.

25. In the process of purifying molten aluminum the steps comprising:

26. The process according to claim 25 wherein the agitation conditions maintained are such as are derivable by a turbine blade 12 inches in outside diameter having 12 paddles of about 2 inches by 2 inches and rotating at a speed of from 150 to 400 rpm.

27. The process according to claim 26 wherein the rotation speed of said turbine blade is from 150 to 275 rpm.

28. The process according to claim 25 wherein the agitation conditions are produced by a multiple bladed impeller rotating at a peripheral speed of 8 to 20 feet per second.

29. The process according to claim 28 wherein the said gas flux is introduced to the central portions of the agitation zone of said impeller.

30. The process according to claim 25 wherein the agitation conditions are produced by a multiple bladed impeller rotating at a peripheral speed of 8 to 14 feet per second.

31. The process according to claim 26 wherein the ratio of the smaller dimension across the body of the molten metal in inches to the diameter of impeller in inches is between 1.5 and 2:

1.

32. The process according to claim 25 wherein said agitation conditions are effected by a rotating vaned impeller operated so as to be equivalent to a turbine blade 12 inches in outside diameter having 12 paddles of about 2 inches by 2 inches and rotating at a speed of from 150 to 400 rpm and the ratio of the smaller dimension across the body of the molten metal in inches to the diameter of impeller in inches is between 1.5 and 2:

1.

33. The process according to claim 25 wherein said gas also comprises a non-reactive gas in addition to said chlorinaceous gas.

34. The process according to claim 25 wherein said amount of gas introduced is at least 0.005 SCF per pound of molten aluminum treated.

35. The process according to claim 33 wherein the relative amount of chlorinaceous gas is small in comparison to the non-reactive gas.

36. The process according to claim 25 wherein the chlorinaceous gas is chlorine and the non-reactive gas is selected from argon or nitrogen or mixtures thereof and the amount of chlorine is relatively small in comparison with the non-reactive gas.

37. The process according to claim 25 wherein the agitation conditions maintained are such as are derivable by a turbine blade 12 inches in outside diameter having 12 paddles of about 2 inches by 2 inches and rotating at a speed of from 150 to 400 rpm.

38. The process according to claim 25 wherein the chlorinaceous gas is chlorine.

39. The process according to claim 25 wherein impurity metal chloride salt reaction product is removed from said chloridization chamber to prevent an excessive build-up of salt so as to maintain said substantially 10 inch or more metal depth above said chlorinaceous gas introduction site.

40. The process according to claim 25 wherein said chlorinaceous gas is provided in an amount stoichiometrically related to a preselected portion of said impurities to be removed.