Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/10—Supplying or treating molten metal
  • B22D11/11—Treating the molten metal
  • B22D11/113—Treating the molten metal by vacuum treating
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
  • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
  • C21C7/10—Handling in a vacuum
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
  • C22B9/04—Refining by applying a vacuum

Definitions

• the invention relates to a process for the continuous degassing of molten metals, preferably molten copper, and subsequently casting the degassed metal, the molten metal being passed into a vacuum atmosphere for degassing and being transferred to a casting chamber after degassing.
• the invention further relates to a device for the continuous degassing of molten metals, preferably molten copper, and subsequent casting of the degassed metal, with a container holding the supplied molten metals, a riser pipe projecting into this chamber, the upper end of which opens into a degassing chamber, and with a drain for the molten metal.
• the degassing of molten metals is basically known under the keyword vacuum treatment. This is understood to mean post-treatment of molten metal under greatly reduced pressure, which is based on the knowledge that the gases dissolved in the molten metal, in particular hydrogen, escape when the external pressure is reduced.
• partial quantity degassing that is considered here in general, only a part of the liquid melt is exposed to the vacuum, either by means of a vacuum circulating degassing or a vacuum lifter degassing.
• the nozzle-shaped end is immersed in the melt by lifting and lowering the vacuum vessel.
• the vacuum vessel is lowered, part of the melt rises into the vacuum vessel with vigorous movement. If the vacuum vessel is then raised, the steel flows back into the pan due to its own weight. Through repeated use, partial quantities can thus gradually get into the degassing room, so that after a treatment period of around 15 minutes, the pan contents are pushed through and degassed several times.
• a preferred area of application of the methods presented is the production of oxygen-free copper (OF copper), in which, in addition to low oxygen contents of the order of 1 to 3 ppm, low hydrogen contents of typically less than 1 ppm must also be achieved.
• OF copper oxygen-free copper
• the object related to the method is achieved by the measures according to claim 1, wherein according to the invention the metal melt is transferred from a first chamber via a riser pipe with an inlet opening below the bath level to a vacuum chamber serving as a degassing chamber and from there due to gravity into a down pipe with a lower one Outlet opening, which is preferably located below the bath level in the casting chamber, is discharged into the casting chamber.
• This process technology has the advantage that the molten metal which is transferred to the casting chamber has been completely degassed beforehand during the previous passage through the vacuum chamber. Mixing of already degassed molten metal with an untreated molten metal is thus avoided. Furthermore, only one vacuum chamber is required, into which the molten metal is transferred using only the lifting force resulting from the pressure differences between the vacuum chamber and the first vessel and with the exclusion of further conveying means, and is removed from there. In contrast to the method described in the prior art, continuous operation is possible according to the invention.
• the bath levels in the first chamber and the casting chamber are adjusted to different height levels by regulating the supply of molten metal into the first chamber and draining the molten metal from the casting chamber.
• a connection is created between the two chambers, which works in the manner of the communicating tubes, a metal melt flow being maintained in accordance with the height difference between the higher bath level in the first chamber and the bath level in the casting chamber.
• the molten metal can be discharged continuously or discontinuously from the casting chamber.
• the first and the second chamber are spatially connected to one another and divided into two bath chambers by a dam in the lower region.
• the bath levels in the first and the second chamber are below the upper edge of the dam, the molten metal is led out of the first chamber via the riser pipe into the vacuum chamber and from there via the down pipe into the casting chamber.
• the bath level is adjusted so that it lies above the edge of the said dam, so that there is a common one in the first and the second chamber continuous bath level and that molten metal gets directly into the casting chamber bypassing the vacuum chamber.
• the riser pipe and the downpipe are heated.
• the heating is carried out with burners.
• the degassing kinetics depend very much on the temperature, which is why, according to a further embodiment of the invention, the molten metal is heated inductively, making it possible to control the degassing.
• the duration of stay of the molten metal in the vacuum chamber is regulated by the pressure in this vacuum chamber.
• the object on which the present invention is based is achieved by the device according to claim 7, which is characterized in that the riser projects into a first chamber which has an inflow for the molten metals and that a vacuum chamber is provided for degassing. hen, in the bottom of which the upper end of the riser pipe opens, that the bottom has a drain opening which is connected to a downpipe, the lower end of which forms an outlet opening and opens into a second chamber formed as a casting chamber with an outlet nozzle.
• the first and the second chamber are preferably spatially connected to one another and have a dam which divides the chambers in the lower region into two bath chambers, the riser pipe and the down pipe opening into different regions below the upper dam edge.
• the molten metal present in the first chamber can only get into the casting container via the riser pipe, the vacuum chamber and the down pipe, as long as the bath levels on both sides of the dam lie below the upper dam edge. This must be taken into account by regulating the flow of molten metal into the first chamber and by removing the treated molten metal from the casting chamber. If the vacuum chamber fails, the "dam is flooded" so that the casting process does not have to be interrupted even if no degassing is desired or if the vacuum chamber fails.
• the riser pipe and the down pipe are preferably arranged vertically parallel to one another.
• the riser pipe and the down pipe are heated, in particular with at least one burner.
• Appropriate regulations or controls ensure that the bath levels are adjustable below or above the upper edge of the dam. It is also preferred to control the temperature of the molten metal in the inlet area Inductor arranged, via which a heating of the molten metal to the desired temperatures for controlling the degassing can be ensured during continuous operation.
• it is sealed off from the outside by a weir that ends below the level of the bath.
• 1 and 2 are cross sections through a device according to the invention.
• the system shown has a pouring chamber 10, into which the liquid metal is continuously filled from an upstream storage furnace. From this pouring chamber 10, the molten metal runs through an inductor channel or channels 11 into the first chamber 20, into which a vertically arranged riser pipe 15 projects, so that the riser pipe with its lower opening lies below the bath level.
• the riser pipe 15 and the down pipe 16, which protrudes into a casting chamber 13 and whose lower opening is also below the bath level there, are designed in the form of connecting pieces of the bottom of the vacuum chamber 17, which can be evacuated via a connecting piece 18 by means of a pump.
• the casting chamber 13 and the first chamber 20 are separated from one another by a dam 12.
• the molten metal can, as shown in FIG. 1, only from the first chamber 20 via the riser pipe, the vacuum chamber 17 and the down pipe in reach the casting chamber 13.
• burners 19 are provided which heat the riser pipe 15 and the down pipe 16. Compared to inductive heating, this burner heating has the advantage that it allows the entire chamber, including the risers, to be preheated.
• the casting chamber 13 also has a nozzle 14, through which the molten metal can be drained.
• the casting chamber 13 is separated from the rest of the furnace atmosphere by a weir 24, so that the casting chamber is hermetically sealed from the outside. The weir ends with its lower edge below the bath level in the casting chamber.
• the device according to the invention works as follows:
• the pouring chamber 10 is continuously filled with molten metal via an inlet, the bath level lying between the boundary lines 21 and 22.
• a vacuum is set in the vacuum chamber 17, which causes the molten metal to rise above the riser pipe 15 and is degassed in the vacuum chamber 17.
• the molten metal flows through the downpipe 16 beyond the dam 12 into the casting chamber 13 as long as the bath level there is below the level of the bath level of the pouring chamber.
• the burners 19 are operated, which ensure adequate temperature control.
• the level of the bath level 27 in the container 22 corresponds in each case to the static pressure in the vacuum chamber 17.
• the bath level in the first chamber 20 is adjusted so that the dam 12 is flooded so that the molten metal can get directly into the casting chamber 13.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Continuous Casting (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Furnace Details (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=7874091

Family Applications (1)

Country Status (5)

Cited By (1)

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Citations (7)

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• 1999
  • 1999-07-01 DE DE59901564T patent/DE59901564D1/de not_active Expired - Lifetime
  • 1999-07-01 JP JP2000559951A patent/JP2002520162A/ja active Pending
  • 1999-07-01 WO PCT/DE1999/002028 patent/WO2000003821A1/de not_active Ceased
  • 1999-07-01 US US09/719,819 patent/US6454829B1/en not_active Expired - Fee Related
  • 1999-07-01 EP EP99944261A patent/EP1105234B1/de not_active Expired - Lifetime

Patent Citations (7)

Non-Patent Citations (5)

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