DEVICE FOR MELTING METALS

Abstract

An apparatus for melting metals whose melting temperature is below 1000° C. may have a device for forming a plasma arranged on a melting furnace. The device is connected to an electrical voltage supply and to the device at least one first supply for a plasma gas, with which the plasma can be formed, and is designed, dimensioned, arranged and/or aligned in such a way that the formed plasma is arranged at a distance from the metal as the material to be melted, and in this case a hot gas stream can be formed with the plasma, which hot gas stream is aligned in the direction of the material to be melted, and a melting tank or crucible is arranged in the melting furnace to receive the molten metal.

Claims

1-16. (canceled)

17. An apparatus for melting non-ferrous metals, comprising: a device for forming a plasma is arranged on a melting furnace, the device being connected to an electrical voltage supply and at least one first feed for a plasma gas, with which the plasma can be formed, being connected to the device, and the device being designed, dimensioned, arranged and/or aligned in such a way that the plasma formed is arranged at a distance from the metal as the material to be melted, and in this case a hot gas stream can be formed with the plasma, which hot gas stream is aligned in the direction of the material to be melted, and a melting tank or crucible is arranged in the melting furnace to receive the molten metal.

18. The apparatus according to claim 17, wherein the device is designed in such a way that plasma gas of the plasma and further gas form a free gas torch or plasma torch in the furnace chamber of the melting furnace which can use its hot gases and radiation energy for heat transfer and melting of a respective metal.

19. The apparatus according to claim 17, wherein the device is provided with a microwave generator and resonator connected thereto, which is designed as a waveguide and has at least one reflection plate for generated microwaves.

20. The apparatus according to claim 19, wherein the device is formed with an electrical ignition device, with an ignition electrode electrically insulated from a housing, the plasma being formed in the region of standing microwaves inside the resonator in front of the at least one reflection plate with plasma gas flowing there, and the plasma being formed in the housing.

21. The apparatus according to claim 20, wherein the hot gas flow is directed in the direction of the melt material via at least one flow guide element.

22. The apparatus according to claim 20, wherein the ignition electrode of the electric ignition device for plasma is arranged in a radiation trap.

23. The apparatus according to claim 17, wherein the power, the length, the temperature and/or the length of a free gas flare or a plasma flare can be varied with a controllable microwave generator.

24. The apparatus according to claim 17, wherein the device is formed with two electrodes which are arranged at a distance from one another and between which a plasma gas flows in the direction of the material to be melted and an electric arc discharge takes place.

25. The apparatus according to claim 17, wherein more than one supply for plasma gas or a more than one gas is connected to the housing of the device.

26. The apparatus according to claim 19, wherein electrical power of the microwave generator or an electrical arc discharge of the device, a volumetric flow of the plasma gas and/or a volumetric flow of the further gas can be controlled.

27. The apparatus according to claim 17, wherein at least the plasma gas and/or a further gas flows tangentially into the housing with a swirl.

28. The apparatus according to claim 27, wherein argon is used as the plasma gas and/or further gas.

29. The apparatus according to claim 19, wherein microwaves having a frequency in the range 500 MHz to 5000 MHz, at an electrical power in the range 5 kW to 3000 kW are used.

30. The apparatus according to claim 17, wherein a gas mixture is used as plasma gas and/or a further gas.

31. The apparatus according claim 17, wherein a recirculation system for hot gas withdrawn from the melting furnace is provided, by which a renewed use of this gas as plasma gas and/or further gas in the cycle or another use of the residual heat is achievable.

32. The apparatus according to claim 17, wherein the device is fixed to the furnace body in a pivotable device, so that a targeted and variable guidance of a gas flare, a plasma flare or a hot gas flow in the furnace chamber is made possible.

Description

[0036] In the following, the invention will be explained in more detail by way of example. Features can be combined with each other regardless of the particular example or the corresponding illustration in a figure. The individual features are not limited to the particular example or illustration.

[0037] Shown are:

[0038] FIG. 1 a schematic representation of an example of an apparatus according to the invention and

[0039] FIG. 2 a sectional view through a portion of an example of a device for forming a plasma using microwaves.

[0040] FIG. 1 schematically shows an example of an apparatus according to the invention with a melting furnace 1. On one side of the melting furnace 1 there is a door (not shown) through which it is possible to feed the melting furnace 1 with unmelted melt material 9. The unmelted melt material 9 may be deposited on a melting platform 4 which is inclined at an angle, in the example shown an angle of 10°, so that molten metal can drip off the melting platform 4 into the crucible 5 or a melting tank not shown.

[0041] A device 2 for forming a plasma is flanged to the housing 6 of the melting furnace 1, and at least one flow guide element not shown here for a hot gas flow hot gas stream is guided through the housing wall of the melting furnace 1 into the interior of the melting furnace 1, so that at least one hot gas flow can be directed onto the unmelted melt material 9. The housing is pivotally mounted so that this allows the gas, plasma torch or a hot gas stream formed with the plasma 8 to be tracked during melting.

[0042] By means of a viewing window recessed in the housing wall 6 of the melting furnace 1, it is possible to observe the melting process from the outside or it is also possible to determine the temperature inside the melting furnace 1 from there.

[0043] In FIG. 1, there is also an exhaust 7 for hot exhaust gas on the melting furnace 1, through which hot exhaust gas can be extracted from the melting furnace 1. The hot exhaust gas can be recirculated and recycled, for example as plasma gas or other gas.

[0044] Extracted hot exhaust gas may also be used to keep molten metal warm or for some other use where one can utilize the heat energy.

[0045] Hot exhaust gas can also be passed through a heat exchanger.

[0046] FIG. 2 shows essential elements of a device 2 for forming a plasma. A microwave generator, which may be a commercially available product, has not been shown. It is flanged to the resonator 10.

[0047] The microwaves 11 generated by the microwave generator can be obtained as standing waves in the resonator 10. For this purpose, a reflection plate 10.1 is also arranged in a flange of the housing 13 of the device 2 opposite a second flange 21. The microwave generator is connected to the second flange 21.

[0048] The reflection plate 10.1 may be formed of a glass. In the vicinity of the reflection plate 10.1 for microwaves, a feed 17 for a cooling gas is provided in the housing 13 of the device 2. In addition to its cooling effect, cooling gas can also flow along the surface of the reflection plate 10.1 inside the housing 13 and clean it or keep it free of particles.

[0049] In FIG. 2, an ignition device with a rod-shaped ignition electrode 12 can be seen on the left of the housing 13 of the device 2. The ignition electrode is connected to one pole of an electrical voltage source not shown. If an electrical voltage is applied to this ignition electrode 12 for a short time, an additional increase in the energy of supplied plasma gas can be achieved, which leads to the ignition of a plasma 8 in the area of the resonator 10 and standing microwaves 11 formed there. After the plasma 8 has been ignited, the ignition device can be switched off.

[0050] The housing 13 can be designed in the area of the ignition device with the ignition electrode 12 as a radiation trap, as explained in the general part of the description.

[0051] Plasma gas may enter solely through the radiation trap or solely through inlets 18 distributed around the circumference of the housing 13. However, a combination of these is also possible.

[0052] A swirl effect can be achieved and exploited by a tangential inflow through preferably several inlets 18.

[0053] In the example shown, a further feed for another gas has been omitted. However, at least one additional gas can be introduced into the housing 13 of the device 2, preferably in the area of the formed plasma gas 8. Further gas can then be used at least predominantly for the hot gas stream.

[0054] The hot gas stream leaves the device 2 in the direction of the arrow shown. For this purpose, three tubular flow guide elements 14, 15 and 16 are present in this example. The quartz glass tube 14 with the smallest diameter encloses the formed plasma 8. It is enclosed in its region facing in the direction of the melting furnace 1, which is arranged opposite the ignition device, by a further tubular flow guide element 15, which can simultaneously form a shield against thermal radiation.

[0055] In the area of the flange of the housing 13, which is arranged facing in the direction of the melting furnace 1, a third tubular flow guide element 16, the diameter of which is the largest, is arranged. The third flow guide element 16 may be guided at least as far as the wall of the housing 6 of the melting furnace 1, so that the hot gas stream can be directed through an opening in the wall of the housing 6 onto the melt material 9 arranged in the melting furnace 1. However, its length can also be selected so that it extends into the interior of the melting furnace 1.

[0056] The third tubular flow guide element 16 may be guided and retained in a flange 19 of the housing 13 of the device 2. The flow guide elements 14, 15 and 16 are inserted into each other. However, they should not contact one another.

[0057] In addition to the supply 17 for a cooling gas, other areas of the housing 13 of the device 2 can be designed and used for cooling. For this purpose, a cooling medium (gas or liquid) can flow through these areas. These areas should be arranged at least in the vicinity of the formed plasma 8.

[0058] In the example shown, flanged cooling 20 is provided in a portion of the housing 13 of the device 2.