EP1568790A1 - Apparatus for the treatment of liquid metal in a ladle - Google Patents

Abstract

A device for the treatment of molten metal in a ladle comprises a rotary bell equipped with a bearing allowing rotary movement of the bell, the bearing incorporating an upper part integral with the bell and a lower part able to turn freely, a drive system to rotate the bell around a vertical axis and a bell manipulation device. The manipulation device comprises: (A) a first means of blocking the rotary bell able to engage the lower part of the bearing by the arms in a manner to support the weight of the bell; (B) a second system of blocking of the rotary bell able to engage with the lower part of the bearing from the top in a manner to prevent vertical movement towards the top of the bell.

Description

The present invention relates to a device for the treatment of metal liquid, in particular steel in the pocket.

There is currently a series of metal processing processes liquid, in particular pocket steel, according to which a bell or a tube is dipped into the liquid metal contained in a pocket. Such methods of processing are among others so-called CAS, CAS-OB, HALT, etc. processes.

In this type of process, the liquid metal contained in the pocket is subjected to different treatments in a confined area, delimited by the bell diving into the liquid metal. Below the bell, we inject a gas of bubbling into the liquid metal to homogenize during the treatment. He is therefore forms on the surface of the liquid metal turbulences which lead to increased local wear of the bell on its lower edge.

PCT Patent Application WO98 / 31841 describes a method for minimize local wear of a bell during liquid metal processing in the pocket. The bell is rotated around its perpendicular axis in order to minimize local wear of the bell during the treatment of liquid metal in poached. As the bell rotates during the treatment of the liquid metal, a increased wear at a given location due to turbulence in the liquid metal no longer to be feared. The bell wears in effect regularly on all its sound periphery.

• sur un côté "chaud", la cloche ou plus précisément le revêtement réfractaire du bord inférieur de la cloche est attaqué(e) par des chocs thermiques et par corrosion chimique sous l'effet de projections de métal et de laitier . L'usure se fait principalement par écaillage du revêtement réfractaire.
• sur le côté "froid" et éventuellement en utilisation intermittente lorsque le réfractaire s'est refroidi, la cloche "s'engraisse" par solidification de projections de métal et/ou de laitier.

Such rotating bells are particularly useful during the implementation of the method for treating the liquid steel in the pocket described in European Patent EP 0 110 809. In such a process, by which the steel contained in the invention is heated. pouch by aluminothermie and by which a number of alloying elements are added to the steel, the bell is solicited asymmetrically:

• on a "hot" side, the bell or more precisely the refractory lining of the lower edge of the bell is attacked by thermal shocks and chemical corrosion under the effect of splashes of metal and slag. Wear is mainly by peeling off the refractory lining.
• on the "cold" side and possibly in intermittent use when the refractory has cooled, the bell "greases" by solidification of metal splashes and / or slag.

These phenomena of local wear and fattening reduce considerably longer the life of the bell and thus increase the cost of production by the method of addition and heating under bell. Use of a rotating bell prolongs the duration of use of a refractory bell, by minimizing local wear and reducing local fattening.

Normally these rotating bells are suspended in a clamp so as to allow their rotation about their vertical axis and are lowered in the liquid metal bath by means of a suitable device.

It is important for the proper functioning of such power bells guarantee a certain depth of penetration of the lower edge of the bell in the liquid metal. However, it has been surprisingly found that in certain conditions, bells that can weigh several tons, begin to float on the liquid metal in the pocket. In these conditions and given the suspension mechanisms used, it is not possible to guarantee a constant depth of penetration.

The problem underlying the invention therefore consists in proposing a rotary bell for the treatment of liquid metal in a pocket which can be maintained at a certain depth of penetration determined in the metal in all conditions.

Usually the penetration depth of such a bell is approximately 10-50 cm and preferably between 20 and 40 cm, ie the edge The bottom of the bell is immersed over a distance of 10 to 50 cm below the surface of the liquid metal covered if necessary with slag.

• un premier moyen de blocage de la cloche rotative pouvant engager la partie inférieure du palier par le dessous de façon à supporter le poids de la cloche,
• un deuxième moyen de blocage de la cloche rotative pouvant engager la partie inférieure du palier par le dessus de façon à empêcher le mouvement vertical vers le haut de la cloche.

To achieve this objective, the present invention provides a device for treating liquid metal in a bag comprising a rotary bell equipped with a bearing allowing a rotational movement of the bell, the bearing comprising an upper portion secured to the bell and a lower portion. freely rotatable, a drive device for driving the bell in a rotational movement about a vertical axis and a device for handling the bell. Said handling device comprises:

• a first means of locking the rotary bell which can engage the lower part of the bearing from below so as to support the weight of the bell,
• a second locking means of the rotary bell which can engage the lower part of the bearing from above so as to prevent vertical movement up the bell.

Even though slag fattening is formed on the lower edge of the bell that increase buoyancy, the bell may be maintained at a predetermined immersion depth. The device drive of the bell is thus also protected.

According to a first advantageous embodiment, the first means of locking of the rotary bell comprises a first clip that can engage the bell below the lower part of the thrust bearing.

The second locking means of the rotary bell can meanwhile either include one or more jacks bearing on the top of the part lower part of the bearing or a second clamp able to engage the bell above the lower part of the thrust bearing.

According to another embodiment, the first blocking means and the second blocking device are made in one piece comprising a V-shaped notch that can snap into the bottom of the bearing.

The training device may advantageously comprise a toothed ring integral with the bell driven by a motor through a gear wheel.

The rotation speed of the bell is usually between 0.5 and 2 rpm during the treatment of the liquid metal. The rotation speed of the bell can be adapted according to the diameter of the bell, depending on the treatment applied to the liquid metal and / or depending on the composition and viscosity of the slag which covers the liquid metal in the pocket. Of course, the bell may continue to rotate around its axis even when removed bath after the treatment of the liquid metal.

The bell is rotated about a vertical axis, substantially perpendicular to the surface of the liquid metal respectively of the liquid steel.

• la Figure 1 montre une section transversale d'une cloche et une poche remplie au repos;
• la Figure 2 montre un agrandissement en coupe d'un dispositif d'entraínement de la cloche,
• La Figure 3 montre une vue d'ensemble du dispositif de manipulation de la cloche au moment du chargement d'une cloche,
• la Figure 4 montre une séquence de couplage d'une cloche selon un premier mode de réalisation,
• la Figure 5 montre une séquence de couplage d'une cloche selon un deuxième mode de réalisation,
• la Figure 6 montre une séquence de couplage d'une cloche selon un troisième mode de réalisation,
• La Figure 7 montre un agrandissement du dispositif de couplage de la figure 6.

A preferred embodiment of an installation according to the invention is described with the aid of the accompanying drawings, in which:

• Figure 1 shows a cross section of a bell and a filled bag at rest;
• FIG. 2 shows an enlargement in section of a device for driving the bell,
• Figure 3 shows an overview of the device for handling the bell when loading a bell,
• FIG. 4 shows a coupling sequence of a bell according to a first embodiment,
• Figure 5 shows a coupling sequence of a bell according to a second embodiment,
• Figure 6 shows a coupling sequence of a bell according to a third embodiment,
• Figure 7 shows an enlargement of the coupling device of Figure 6.

A pocket 10 (FIG. 1) comprising a refractory lining 15 filled with of liquid steel 20 is placed on a carriage 25 and is brought below a refractory bell 30. In the working position, during the treatment of the metal liquid, the bell 30 is lowered until its lower edge 40 is immersed in liquid steel 20.

The bell 30 is connected to a supply duct 50 (FIG. combustible materials and alloying elements are introduced into the steel 20. It includes a training device 60 that can cause the bell in a rotational movement about a vertical axis.

Inert or reducing sparge gas can be introduced into the steel liquid 20 or by a porous plug (not shown) arranged in the bottom of the pocket 10 is by a lance (not shown) which is introduced into the This splash gas serves to homogenize the liquid steel 20 contained in the pocket 10 during the treatment of steel 20. This bubbling gas creates turbulence on the surface of the steel 20 which causes local wear of the bell 30 and in particular the lower edge 40 of the bell 30.

Figure 2 shows an enlarged view of the training device 60 of the bell 30. The upper end of the bell 30 comprises a ball bearing 70 integral with the bell 30 which allows the bell 30 to make a movement of rotation around its vertical axis. The upper part 75 of the level 70 is attached to the bell 30 while the lower portion 80 of the bearing 70 can rotate freely. When the bearing 70 is not under stress, the lower part 80 leans against an abutment 85 arranged below the landing 70. Of course, this bearing 70 must be protected against the penetration of impurities.

The bell 30 is held in position by means of a locking system taking support from below and from above on the lower part 80 of bearing 70 which pushes the bell 30 against the supply conduit 50. On the upper part 75 of the bearing 70 is fitted with a ring gear 90. The rotation of the bell 30 is carried out using a motor 100 comprising preferably a gearbox 110 for varying the speed of rotation of the bell 30. The motor 100 drives the ring gear 90 via of a gear 120 integral with the motor 100. Of course, there are other means well known to those skilled in the art to impregnate a movement of rotation to such a bell. The sealing of the supply duct 50 with respect at the bell 30 is provided by a baffle 130. The bell 30 and the conduit feed 50 comprise an inner liner of refractory material. This coating is not shown in the figures for the sake of clarity drawing.

In FIG. 3, the pocket 10, placed on a carriage 140, is brought into below a bracket 150 which includes a mobile platform 160, equipped of a bell 10, a mat 170 and a drive device 180 on the part superior of it. The platform 160 is connected to the training device 180 by means of a belt 190 thanks to which the platform can be moved vertically on the mat 170 using the wheels 200 that take support on the mast of the gallows.

Figures 4, 5 and 6 show, in section, sequences interlocking three different locking mechanisms of the bell. To do not overload the drawings, only the lower part 80 of the level 70 has been represented.

The first series of Figures 4a), 4b), 4c) and 4d) show, in section, a first embodiment of the present invention in which the first locking means and the second locking device are made in one piece comprising a V-shaped notch that can engage on the lower part of the landing.

In FIG. 4a), the platform 160 is lowered on the upper part 210 of the bell 10 to below the lower portion 80 of the bearing. The platform 160 is then raised until the blocking device V-shaped 220 is located at the lower portion 80 of the bearing (FIG. 4b).

In Figure 4c), the V-shaped locking device is closed for block the bell 10 thus preventing downward and forward movements 10. The bell is then lifted (Figure 4d) to its top. rest position (see Figure 1)

In the next two series, the blocking devices are made of two separate rooms.

In FIG. 5a), the platform 160 is lowered on the upper part 210 of the bell 10 to below the lower portion 80 of the bearing. The first blocking device 230 in this case a clamp - is then brought to the closed position (FIG. 5b) and the platform 160 is then raised until the first locking device 230 touches the lower part 80 bearing from below (Figure 5c). The second blocking device is then closed and prevents any movement of the bell upwards. The bell is then raised and brought to rest position. In the case of Figure 5, the second locking device comprises four spaced jacks regularly (only two are shown in Fig. 5). They went up on the platform using arms 250. The cylinders 240 are then brought into position. closed position and support from above the lower part of the bearing of the bell (Figure 5d)).

In the case of FIG. 6, the second blocking device is a clamp 260 superimposed on the first clamp 230. The second clamp 260 is closed and thus blocks the bearing to prevent any upward movement.

In Figure 7, the two clamps 230, 260 blocking are shown in more detail in the open position around the upper part of the bell. Table of references 10 poached 15 refractory coating 20 liquid steel 25 trolley for the pocket 30 refractory bell 40 lower edge 50 supply duct 60 drive device 70 ball bearing 75 upper part of the bearing 80 lower part of the bearing 85 stop 90 toothed crown 100 engine 110 reducer 120 gear wheel 130 quibble 140 trolley for the bell 150 gallows 160 platform 170 mast 180 drive device 190 belt 200 wheels 210 upper part of the bell 220 V-shaped locking device 230 first locking device (first clamp) 240 jack 250 arms 260 second blocking device (second clamp)

Claims (6)

Device for treating liquid metal in a pocket comprising a rotary bell equipped with a bearing allowing a rotational movement of the bell, the bearing comprising an upper part integral with the bell and a lower part which can rotate freely, a drive device enabling driving the bell in a rotational movement about a vertical axis and a device for manipulating the bell, said manipulation device comprising: a first means of locking the rotary bell which can engage the lower part of the bearing from the bottom so as to support the weight of the bell a second locking means of the rotary bell which can engage the lower part of the bearing from above to prevent vertical movement up the bell. Device according to claim 1, characterized in that the first locking means of the rotary bell comprises a first clamp which can surround the bell below the lower part of the abutment bearing. Device according to claim 1 or 2, characterized in that the second locking means of the rotary bell comprises one or more jacks bearing on the top of the lower part of the bearing. Device according to claim 1 or 2, characterized in that the second locking means of the rotary bell comprises a second clip which can surround the bell above the ring Device according to claim 1, characterized in that the first locking means and the second locking device are made in one piece comprising a V-shaped notch which can engage on the lower part of the bearing. Device according to any one of the preceding claims characterized in that the drive device comprises a ring gear integral with the bell driven by a motor through a toothed wheel.

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