Quiescent transfer of melts

• US 20080202644A1
• Filed: 02/23/2007
• Published: 08/28/2008
• Est. Priority Date: 02/23/2007
• Status: Abandoned Application

• Current Assignee: Alotech, Ltd.
• Original Assignee: Alotech, Ltd.
• Inventors: Campbell, John, Grassi, John R.
• Application Number:
  US11/710,452
• Publication Number:
  US 20080202644A1
• Time in Patent Office: Days
• US Class Current: 148/538
• CPC Class Codes: C22B 9/006 with use of an inert protective material including the use of an inert gas
• CPC Class Codes: C22B 9/023 By filtering filtration of aluminium C22B21/066
• CPC Class Codes: F27B 3/045 Multiple chambers, e.g. one of which is used for charging
• CPC Class Codes: F27D 3/145 Runners therefor
• CPC Class Codes: Y02P 10/20 Recycling

Abstract

A quiescent melt handling system includes a holding furnace (2, 120, 320-720) for a molten metal melt. The holding furnace has a relatively large surface area and a relatively shallow depth, having a width to depth ratio in the range of 4-100 to 1. Also provided is structure (650-680) in the holding furnace for separating inclusions from the melt in the holding furnace. A quiescent transfer casting method includes melting a metal to form a melt and transferring the melt into a holding furnace. A hydrogen content in the melt is passively equilibrated with a dry atmosphere maintained in the holding furnace. Subsequently, the melt is withdrawn from the holding furnace.

Claims

1. A quiescent melt handling system comprising:

a holding furnace for a molten metal melt, wherein said holding furnace comprises a relatively large surface area and a relatively shallow depth having a width to depth ratio in the range of 4-100 to 1; and

a means for separating inclusions from the melt in said holding furnace.

2. The system of claim 1 further comprising:

a melting furnace; and

,

a conduit communicating said melting furnace with said holding furnace such that a level of the molten metal melt in said melting furnace and said holding furnace is substantially equal.

3. The system of claim 2 wherein said melting furnace comprises a dry hearth furnace, including a sloping hearth.

4. The system of claim 1 further comprising a means for replenishing a dry atmosphere in said holding furnace, wherein said holding furnace allows hydrogen in the melt to equilibrate with the dry atmosphere being replenished into said holding furnace.

5. The system of claim 4 wherein the means for replenishing comprises a gas inlet located adjacent an outlet of said holding furnace so that a counter current flow of the dry atmosphere takes place.

6. The system of claim 3 wherein said holding furnace further comprises a dry heating means.

7. The system of claim 3 wherein said holding furnace has a length in the range of 1 to 200 meters and wherein a length to width ratio is in the range of 1-100 to 1.

8. The system of claim 1 wherein said means for separating inclusions comprises at least one of a filter and a flow obstructing device.

9. The system of claim 1 further comprising a pump furnace positioned downstream from said holding furnace and communicating therewith at the same melt level wherein said pump furnace comprises:

a well; and

,

a pump mounted in said well.

10. The system of claim 1 further comprising a snorkel ladle which selectively withdraws melt from said holding furnace and transfers it to an associated casting station.

11. A quiescent transfer casting method comprising:

melting a metal to form a melt;

transferring the melt into a holding furnace;

passively equilibrating a hydrogen content in the melt with a dry atmosphere maintained in the holding furnace; and

,

subsequently withdrawing the melt from the holding furnace.

12. The method of claim 11 further comprising maintaining a substantially fixed horizontal level of a melt surface in the holding furnace.

13. The method of claim 12 further comprising avoiding a disturbance of the melt surface and of melt below the surface in the holding furnace.

14. The method of claim 11 further comprising separating inclusions from the melt in the holding furnace.

15. The method of claim 11 further comprising filtering the melt during its stay in the holding furnace.

16. The method of claim 11 further comprising flowing the dry atmosphere in a counter current manner in the holding furnace.

17. The method of claim 11 further comprising passively allowing the melt to flow in the holding furnace.

18. The method of claim 11 wherein said step of withdrawing the melt from the holding furnace includes pressurizing the melt in a pump well furnace, communicating with the holding furnace, with a pump.

19. The method of claim 11 wherein said step of withdrawing the melt from the holding furnace includes employing a snorkel ladle to transfer melt from the holding furnace to a casting station.

20. A quiescent melt handling system comprising:

a melting furnace which transforms solid metal into a melt;

a holding furnace for the melt, wherein said holding furnace comprises a relatively shallow bath having a relatively large surface area and a heater located above a surface of the melt, wherein said holding furnace has a width to depth ratio on the order of at least approximately 4-100 to 1 and a length to width ratio on the order of at least approximately 1-100 to 1;

a first channel communicating said holding furnace with said melting furnace such that a level of the melt in both furnaces is substantially equal; and

,

a means for withdrawing the melt from said holding furnace.

21. The system of claim 20 further comprising a filter located in or adjacent to said holding furnace for filtering the melt flowing into said holding furnace.

22. The system of claim 20 further comprising a means for replenishing a dry atmosphere in said holding furnace, wherein said holding furnace allows hydrogen in the melt to equilibrate with the dry atmosphere being replenished into said holding furnace.

23. The system of claim 22 wherein said holding furnace further comprises a dry-heating means.

24. The system of claim 20 wherein said means for withdrawing the melt comprises a pump furnace including:

a well; and

,

a pump mounted in said well.

25. The system of claim 24 wherein said pump furnace further comprises a crucible mounted in said well, in which crucible said pump and said second filter are located.

26. The system of claim 20 wherein said means for withdrawing the melt comprises a snorkel ladle which selectively withdraws melt from said holding furnace and transfers it to a casting station.

27. The system of claim 20 further comprising a means for separating inclusions from said holding furnace, said means comprising at least one of a filter and a flow obstructing block of material.

28. The system of claim 20 further comprising a gas inlet located adjacent an outlet of said holding furnace so that a counter current flow of a gas takes place in said holding furnace.