ULTRASONIC DEGASSING OF MOLTEN METALS

• US 20110247456A1
• Filed: 04/08/2011
• Published: 10/13/2011
• Est. Priority Date: 04/09/2010
• Status: Active Grant

• Current Assignee: Southwire Company
• Original Assignee: Southwire Company
• Inventors: Gill, Kevin S., Rundquist, Victor F.
• Granted Patent: US 8,574,336 B2
• Time in Patent Office: Days
• US Class Current: 75/392
• CPC Class Codes: C21C 7/072 Treatment with gases C21C7/06, C21C7/064, C21C7/068 take precedence
• CPC Class Codes: C22B 21/06 refining electrolytic refining C25C; C22B21/0046, C22B21/0061 take precedence
• CPC Class Codes: C22B 21/064 using inert or reactive gases C22B21/066 and C22B21/068 take precedence
• CPC Class Codes: C22B 9/00 General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
• CPC Class Codes: C22B 9/02 Refining by liquating, filtering, centrifuging, distilling, or supersonic wave action including acoustic waves; C22B9/003, C22B9/006, C22B9/05, C22B9/22 take precedence
• CPC Class Codes: C22B 9/026 by acoustic waves, e.g. supersonic waves
• CPC Class Codes: C22B 9/05 Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ
• CPC Class Codes: F27D 2003/166 the fluid being a treatment gas
• CPC Class Codes: F27D 2003/169 Construction of the lance, e.g. lances for injecting particles
• CPC Class Codes: F27D 3/16 Introducing a fluid jet or current into the charge porous elements for gas flushing of molten metals B22D1/005
• CPC Class Codes: Y02P 10/20 Recycling

Abstract

Methods for degassing and for removing impurities from molten metals are disclosed. These methods can include operating an ultrasonic device in a molten metal bath, and adding a purging gas into the molten metal bath in close proximity to the ultrasonic device.

Claims

1. A method for reducing an amount of a dissolved gas in a molten metal bath, the method comprising:

operating an ultrasonic device in the molten metal bath; and

introducing a purging gas into the molten metal bath in close proximity to the ultrasonic device.

2. The method of claim 1, wherein the dissolved gas comprises oxygen, hydrogen, sulfur dioxide, or a combination thereof.

3. The method of claim 1, wherein the molten metal bath comprises aluminum, copper, zinc, steel, magnesium, or a combination thereof.

4. The method of claim 1, wherein the purging gas comprises nitrogen, helium, neon, argon, krypton, xenon, or combinations thereof.

5. The method of claim 1, wherein the purging gas is introduced into the molten metal bath at a rate in a range from about 0.1 to about 150 L/min.

6. The method of claim 1, wherein the purging gas is introduced into the molten metal bath at a rate in a range from about 10 to about 500 mL/hr of purging gas per kg/hr of output from the molten metal bath.

7. The method of claim 1, wherein the method results in a reduction of at least about 10 weight percent in the amount of the dissolved gas in the molten metal bath.

8. The method of claim 1, wherein the method results in a reduction of alkali metal impurities in the molten metal bath.

9. The method of claim 1, wherein the dissolved gas comprises hydrogen, and wherein the method results in a reduction of the amount of hydrogen in the molten metal bath to less than about 4 ppm.

10. The method of claim 1, wherein the method is conducted in the substantial absence of chlorine gas.

11. The method of claim 1, wherein the ultrasonic device comprises:

an ultrasonic transducer, and

an elongated probe comprising a first end and a second end, the first end attached to the ultrasonic transducer and the second end comprising a tip; and

wherein the purging gas is introduced into the molten metal bath within about 25 cm of the tip of the ultrasonic device.

12. The method of claim 11, wherein the purging gas is introduced into the molten metal bath within about 5 cm of the tip of the ultrasonic device.

13. The method of claim 11, wherein the purging gas is introduced into the molten metal bath through the tip of the ultrasonic device.

14. A method for reducing an amount of a dissolved gas in a molten metal bath, the method comprising:

operating an ultrasonic device in the molten metal bath, the ultrasonic device comprising;

an ultrasonic transducer, and

an elongated probe comprising a first end and a second end, the first end attached to the ultrasonic transducer and the second end comprising a tip; and

introducing a purging gas into the molten metal bath at a rate in a range from about 1 to about 50 L/min and within about 15 cm of the tip of the ultrasonic device;

wherein;

the dissolved gas comprises hydrogen;

the molten metal bath comprises aluminum, copper, or a combination thereof; and

the purging gas comprises argon, nitrogen, or a combination thereof.

15. The method of claim 14, wherein the purging gas is introduced into the molten metal bath at a rate in a range from about 30 to about 200 mL/hr of purging gas per kg/hr of output from the molten metal bath.

16. An ultrasonic device comprising:

an ultrasonic transducer,

an elongated probe comprising a first end and a second end, the first end attached to the ultrasonic transducer and the second end comprising a tip; and

a purging gas delivery system, wherein the purging gas delivery system comprises a purging gas inlet and a purging gas outlet.

17. The ultrasonic device of claim 16, wherein the purging gas outlet is within about 5 cm of the tip of the elongated probe.

18. The ultrasonic device of claim 16, wherein the purging gas outlet is at the tip of the elongated probe.

19. The ultrasonic device of claim 16, wherein the elongated probe comprises stainless steel, titanium, niobium, a ceramic, or a combination thereof.

20. The ultrasonic device of claim 16, wherein the tip of the elongated probe comprises stainless steel, titanium, niobium, a ceramic, or a combination thereof.