Ultrasonic degassing of molten metals
View Patent ↗Ultrasonic devices having an integrated purging gas delivery system are described, and such devices can be used to remove dissolved gasses and impurities from molten metals.
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, the 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, the purging gas delivery system comprising a purging gas inlet and a purging gas outlet,
wherein the elongated probe comprises a ceramic, and the purging gas outlet is at the tip of the elongated probe; and
introducing a purging gas into the molten metal bath through the purging gas outlet at the tip of the elongated probe.
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 purging gas is introduced into the molten metal bath at a rate in a range from about 1 to about 50 L/min;
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.
12. The method of claim 11 , 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.
13. The method of claim 1 , wherein the elongated probe comprises Sialon.
14. The method of claim 1 , wherein the ultrasonic device further comprises a cooling system surrounding at least a portion of the elongated probe.
15. The method of claim 14 , wherein the cooling system comprises at least one channel surrounding at least a portion of the elongated probe.
16. The method of claim 15 , wherein the channel comprises a fluid.
17. The method of claim 16 , wherein the fluid is argon.