FR2629102A1 - DEVICE FOR INTRODUCING A PROCESSING GAS INTO MOLTEN METAL OF A METALLURGICAL FUSION CRUCIBLE - Google Patents

Abstract

The device for introducing a process gas into molten metal of a metallurgical melting crucible comprising a refractory ceramic gas scavenging brick, and a gas distribution compartment, arranged at its lower end, with a possibility of connecting a gas supply duct 50, is characterized in that the gas distribution compartment 16 has an opening 24, from which a tubular passage channel 26, directed upwards, passes through the sweeping brick 10 up to its upper end face, facing the metal bath, and in that another opening 34 is provided in the gas distribution compartment 16, through which an alloy wire or filler wire 52, or a tube can be introduced into the distribution compartment 16 and the passage channel 26.

Description

The invention relates to a device for the introduction of a gas

  treatment in molten metal contained in a metallurgical melting crucible, comprising a gas sweeping brick, in refractory ceramic and a gas distribution compartment arranged at its lower end with a possibility of connection of a conduit

gas supply.

  A device of this type is known, for example

  by document DE-OS-35 03 222 and document EP-

0242 155.

  In document DE-OS-35.03 222, the sweeping brick is made of a porous refractory ceramic material, through which only gas can pass. The sweeping brick described in document EP-0242 155 certainly has an oriented porosity, but it is also only intended for gas sweeping. The gas distribution compartment is used to standardize its pressure in the brick

scanning.

  Now, there is a need to treat the metallurgical baths not only with gases, in particular inert gases such as argon, but to add alloying substances or additives in solid form to the molten metal. These alloy products, SiMn or CaSi, for example, include additives such as pulverized lime or mixtures of pulverized lime and soda, but also calcium carbide (CaC2) and nitrogenous lime

(CaCN2).

  It is known to introduce these alloying substances or additives in the form of a wire into a metallurgical bath. For this, the wire is led by a guide tube, on the surface of the molten metal and introduced into it, through the surface of the bath. It is important that the constituents of the solid or filling wire are completely dissolved, as they become ineffective as soon as they rise to the surface of the bath or in the layer of slag which floats above this surface. This is the reason why the known solutions have drawbacks, because the distribution and the duration of

  reaction of additives are limited.

  Document DE OS-35 20 207 describes a sweeping brick which is intended to inject gases or solid materials into a ladle containing molten metal. The sweeping brick has a large central passage channel through which gases or solids can be blown. The embodiment described, with a particularly large passage channel, cannot however be used in practice, because with this dimension of the passage channel, the molten metal would certainly penetrate into the sweeping brick and destroy the device. In addition, considerable amounts of gas would be required to maintain an approximately constant gas pressure, and even then it could not be prevented that the molten metal entered

the sweeping brick.

  The object of the invention is therefore to propose a device of the aforementioned type which is suitable not only for gas sweeping, but also for the introduction of solid additives, in particular alloy and filling wires, but also of desulfurization. For this, the device should preferably be designed so that it can also be used exclusively as a sweeping brick. The invention also aims to shape the device so as to improve the possibility of dosing the additives in the metal bath, and also to improve their reactivity and their distribution. The invention is based on the observation that in principle, the devices of the aforementioned type also make it possible, in addition to carrying out a gas sweep, to introduce alloying substances or solid additives, when they are suitably modified. . In particular, with a device comprising a gas sweeping brick with oriented porosity, the refractory material of the matrix comprised between the different channels, can be used to form a passage channel through which an alloy wire will be introduced, for example in molten metal. If this channel leaves the gas distribution compartment, it is at the same time crossed by the gas. In the area of the sweeping brick, therefore, deposits of molten wire cannot form, and the molten metal cannot penetrate into a slot formed between the wire and

the feed tube.

  The object of the invention is to provide a device of the aforementioned type, in which the gas distribution compartment has an opening, from which a tubular passage channel, directed upwards, crosses the sweeping brick up to its front face. upper, facing the metal bath, and another opening is provided in the gas distribution compartment, through which an alloy wire or filler wire, or a tube can be introduced into the distribution compartment and the channel of passage. It is particularly advantageous in this case that the area of the opening through which the wire or the tube is introduced into the compartment.

  gas distribution, is gas tight.

  For this, the skilled person has different means of construction. A particularly advantageous embodiment consists in providing a seal by cable gland, in particular when the latter is placed directly below the corresponding opening of the gas distribution compartment, because then it

  can be operated from the outside.

  In addition to the advantages already mentioned, this device is characterized in particular in that the wire is engaged only in the part of the bath which is in any case the most strongly agitated by the treatment with inert gas of the sweeping brick. Thanks to the agitation of the bath, the products in reaction can be distributed in a particularly homogeneous manner. Finally, it is ensured that the alloying substances will be distributed over the entire height of the molten bath, and that thus their

efficiency will be optimized.

  The device can be further improved by different means of construction. It is proposed to conform the zone surrounding the opening for introducing the wire, in the upper section of the gas distribution compartment, towards the sweeping brick, in the shape of a cone, in the direction of arrival of the wire. In particular, with a new spool of thread, this guarantees that the thread is directly introduced

  in the passage channel, without getting caught.

  The passage channel can either be simply drilled or consist of a steel or refractory ceramic tube which is then preferably sealed with mortar in the matrix material suitably drilled in the injection brick. As the steel grade, an alloy of the X5 type can be used, for example. 6 CuNi 18/9. The ceramic tube can for example be made of aluminum oxide or zirconium dioxide. It can be manufactured in the form of a part obtained by isostatic compression. As has already been said before, the diameter of the tube is preferably a little larger than that of the wire to be introduced; we have optimal dimensions when the inside diameter of the tube is about 1 or

  2 mm more than the diameter of the wire.

  Although the device can be equipped with any type of sweeping bricue (joint sweepers, sweepers with oriented porosity, sweepers with non-oriented porosity), however, a sweeping brick with oriented porosity is preferred, because the wire introduction tube can then be placed between the different channels of the scanning brick. Preferably, the passage channel is placed in the middle and the gas inlet channels are uniformly distributed around the passage channel; the scanning effect and the distribution of the molten alloy wire

is thus favorably influenced.

  If another tube is slidably arranged, but without play in the passage channel or in the fixed tube, the passage channel or the tube can also be used to inject pulverulent solids; in this case, the tube preferably comes out at the bottom of the gas distribution compartment. By means of suitable connection conduits, the powder additives can be injected through the tube, preferably with a stream of inert gas, in the same manner as described for the passage of an alloy wire. By sliding the tube, it is possible to compensate for deposits of molten substances in the zone of contact with the molten metal. Between the different charges, we

6 2 62629102

  can clamp other portions of tube to the lower end of the tube introduced last, or fix them for example by screwing, via corresponding threaded sections, so that one can introduce a tube practically "without end ". An exemplary embodiment of the invention is described below in more detail with reference to the accompanying drawing. The single figure is a very cut

  schematic of a device according to the invention.

  In the figure, the reference 10 designates a gas sweeping brick, which comprises a collection of fine channels 12 with a diameter of approximately 1 mm. We

  sees a total of four channels 12. The channels repo-

  feels in a waterproof refractory matrix which is made of a ceramic material, in this case based on corundum with an A1203 content greater than 97% by weight. But, we can also use other

known types of refractories.

  The sweeping brick 10 rests on a metal box 14 which encloses a compartment for

gas distribution 16.

  The metal box 14 has a circular cross section and its peripheral wall 18 projects upwardly over a cover 20. A volume 21 is thus formed in which the sweeping brick is placed 10. In the cover 20 are made openings 22 which correspond by their number, their dimensions and their location in the channels 12, so that the openings 22 are in the extension of the channels 12 and provide a connection between the channels 12 and the gas distribution compartment 16. In addition to the openings 22, the box metallic 14 has in its cover 20 another central opening 24 of cross section

26 2 9 1 0 2

  round. The opening 24 is larger than the

openings 22.

  Above the opening 24, a passage channel 26, the cross section of which roughly corresponds to the opening 24, passes through the sweeping brick 10. The periphery of the passage channel 26 is limited by a tube 28 zirconium dioxide refractory ceramic, which is embedded in the matrix material of the sweeping brick 10. The tube 28 ends directly on the upper face of the cover 20, while a portion of tube 30, flared towards the bottom cone-shaped, is welded into the opening 24, so that it is practically in the extension of the tube 28, and enters the gas distribution compartment 16. Facing the opening 24, another opening 34 is formed in the bottom 32 of the metal box 14, and a sealing by "stuffing box" 36 is provided below the opening 34. The sealing by stuffing box 36 consists of a press body - cable gland "38 which is screwed against a cable gland flange '40, by sections corresponding threaded rod ions 42, which has the effect of compressing between the two elements 38, 40, a sealing material placed in the packing volume 44. The desired seal is thus obtained. As shown in the figure, a flange 40 is welded to the underside of the bottom 32 of the metal box 14. The figure also shows that the sealing by “cable gland” surrounds a channel of

passage 46.

  Besides the opening 34, a third opening 48 is made in the bottom 32 of the metal box 14. From this, a gas daL'eatian tube 50

extends down.

  Before describing in detail the operation of the device, it should also be noted that the device or the gas sweeping brick 10, is placed in a known manner, in the perforated brick, at the bottom of a

metallurgical melting crucible.

  For commissioning; gas, in particular an inert gas, such as argon, is injected through the supply tube at 50, into the gas distribution compartment 16, from which it is sent, through the channels 12, into the metal in fusion, by the sweeping brick 10. Previously, an alloy wire 52 was introduced into the tube 28, through the cable gland, the gas distribution compartment 16, the portion of tube 30. Gas also reaches the annular gap between the wire 52 and the tube 28, through the gas distribution compartment 16. While the wire is pushed up and it is melted by the molten metal, when it reaches the front face of the sweeping brick 10, it is constantly swept by a stream of inert gas, which prevents deposits of molten wire in the area of the sweeping brick, as well as infiltration of molten metal, in

  this gap, between the wire 52 and the tube 28.

  Depending on the proportion of alloying elements which must be brought in, - the introduction of the

  wire for a specific period of time, while maintaining

  changed the scan by channels 12.

  The gas is prevented from escaping through the opening 34 by choosing as diameter of the passage channel 46 in the region of the seal by the cable gland 36, a diameter equal to that of the outside diameter of the wire, and in this that moreover, the sealing device by cable gland ensures a

additional sealing.

  This arrangement makes it possible to thread the thread from the bottom, which is particularly simple and practical. It is also possible, without problems, to interrupt the supply of wire, because in the passage channel 28, a certain gas pressure is always maintained which prevents infiltration of molten metal or

a fusion of the wire.

  While the portion of tube 30 flared downwards facilitates the initial threading of the wire 52, the device can also be used exclusively for gas sweeping. To this end, a sealed cylindrical plug, preferably made of a refractory ceramic material, such as aluminum oxide, is preferably introduced in a fixed manner, at least in the upper section 28 ′ of the tube 28. The tube 28 is thus closed, while gas may continue to

  flow into the molten metal, through channels 12.

  The channels 12 being arranged around the tube 28, cndotb ue: particularly favorable distribution of the molten particles of alloy in the metal bath, when a wire passes through it. But other arrangements of the channels 12 relative to the tube 28 are naturally

  possible, depending on the area of application.

  Instead of wire 52, it is also possible to introduce a tube into the passage channel, in the same way as for wire 52. Through this sliding tube, it is especially possible to introduce pulverulent substances, in particular at the same time as a flow of inert gas (eg argon) through the tube, through corresponding connection conduits. This tube preferably has a filter at its end protruding downwards from the sealing device 36, which makes it possible to fix another tube, having a corresponding end thread required, it is thus possible to practically push the tube upwards (through the passage channel 28), if cuts by fusion in the region of the front face 54 make this operation necessary. Another tube is preferably connected between the different loads, for this - the supply of gas / solid substances is interrupted, the fittings of the first tube are removed to place them on the next tube. This embodiment also has the same advantages as those mentioned above.

from the introduction of the wire.

Claims (12)

  1. Device for introducing a treatment gas into molten metal contained in a metallurgical melting crucible, comprising a gas sweeping brick (10), made of refractory ceramic and a gas distribution compartment (16) arranged at its lower end with a possibility of connection of a gas supply duct (50), characterized in that the gas distribution compartment (16) has an opening (24), from which a passage channel (26) tubular, directed upwards, passes through the sweeping brick (10) up to its upper front face, facing the metal bath, and in that another opening (34) is provided in the compartment. gas distribution (16), by which an alloy wire or filler wire (52), or a tube can be introduced into the distribution compartment (16) and the passage channel (26).   2. Device according to claim 1 wherein the area of the opening (34) through which the wire (52) or the tube is introduced into the compartment   gas distribution, is made gas tight.   3. Device according to claim 2, in which a seal by cable gland (36) is   provided in the area of the opening (34).   4. Device according to claim 3, in which the sealing by cable gland (36) is   placed directly below the opening (34).   5. Device according to one of claims 1 to   4 in which the area surrounding the opening (24) is   narrows in the direction of arrival of the thread (52).   6. Device according to one of claims 1 to   , in which the passage channel (26) consists of a steel or ceramic tube (28) inserted in the   matrix material of the sweeping brick (10).   7. Device according to claim 5 or 6, wherein the tube (28) or a separate tube portion (30) penetrates down into the gas distribution compartment (16), to flare therein in the form of a cone .   8. Device according to one of claims 1 to   7 in which the internal diameter of the passage channel (26) or of the tube (28) is slightly larger or as large as the external diameter of the wire (52) or of the tube passing through it.   9. Device according to claim 8, in which the internal diameter of the passage channel (26) or of the tube (28) is one or two millimeters more than   the outside diameter of the wire (52).   10. Device according to one of claims 1   to 9, in which the sweeping brick (10) is a brick with oriented porosity.   11. Device according to one of claims 1   to 10 in which the channels (12) are approximately uniformly distributed around the passage channel or of the tube (28).   12. Device according to one of claims 1   to 11 in which the upper section (28 ') of the passage channel or of the tube (28) can be closed by a   refractory ceramic plug, waterproof.