HU187104B - Method and apparatus for discharging tiltable metallurgical melting tanks - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a method for emptying tilting metallic melting tanks and to a device implementing the method.

The process is primarily used for emptying steel converters, the tap opening of which is located on the side wall of a tank containing slag floating on top of a molten metal.

During the tapping of metals, particularly steel, there is usually a certain amount of slag entering the melting pot or other transport or processing tank through the opening of the melting vessel. At the start of emptying, when the converter is tilted to the emptying position, slag enters the tapping opening before the molten steel completely covers the tapping opening. In addition, during the tap, a vortex is formed above the tap opening, which also feeds slag into the pouring pan. At the end of the tap, before the converter is reset, a further amount of slag is added to the casting pan. This adversely affects the durability of the refractory lining of the ladle, as fresh slag is chemically very aggressive. When slag is discharged from the melting tank, with or without molten steel, the latter is reduced by the alloying materials used, such as phosphorus. On the one hand, this can increase the number of inclusions remaining in the material, and on the other hand, due to the high activity of oxygen in the slag, metallurgical processing of fully or partially relaxed steel becomes very difficult and even critical to reduce the sulfur content of the steel.

In the field of metallurgy, various devices are used to prevent slag from being introduced into the pouring pan at the beginning and end of the tap. The most well-known of these are the shut-off valve, the shut-off latch and, above all, ceramic balls or plugs floating in the melting vessel, the density of which is between the density of the molten metal and the slag. As most of the steel flows out of the converter and slag is mixed with the steel, ceramic bodies block the drain opening and thus prevent the slag from leaking. Because the outline of the drain hole is constantly changing during use, the above method does not produce a lasting result.

German Patent No. 2 639 712 discloses a device for sealing a spout having a sealing body which can be inserted into the spout and has a high-pressure gas line, which leaves a gap in the circumference of the spout. The outer jacket of the closure body narrows toward the opening of the gas line. The slag is directed back into the container by the flowing gas. According to a modified embodiment (see EP 10,082), this structure, which is subject to very high wear in the case of large converters, has a closure body whose outer shell changes from a spherical bottle to a truncated cone side. In a preferred embodiment, the closure body itself is made of gray cast iron. The disadvantage of both structures is that it requires a large amount of gas to seal the tap opening, and the additional problem is that the gas must be continuously flushed to avoid blocking the outlet opening in the closure body.

It is known to reduce the amount of slag that is formed by the vortex formed at the beginning of the tap through the spout opening to introduce gas bubbles into the molten metal through nozzles located in the immediate vicinity of the spout. The disadvantage of this solution is that large amounts of gas need to be introduced during emptying and during operation to prevent nozzle clogging. This results in massive cooling of the molten metal, and the nozzles inevitably come into contact with the molten metal and the slag, which shortens their life and is thus less than that of the casting coating. This detrimental result can be explained by the fact that the gas bubbles flowing out of the nozzles are not sufficiently dispersed in the vortex, cannot be eliminated and the slag retained.

It is an object of the present invention to overcome these deficiencies and to eliminate slag runoff during emptying.

The invention is based on the recognition that the tap opening of the hanging vessel must be closed with a closure which only opens the tap opening when liquid steel appears, and that the closure body is inserted into the tap opening shortly when the first slag particles appear. The object of the present invention is achieved by a method for emptying tipping metallurgical melting vessels, in particular steel converters, where a tap opening is formed in the sidewall of the converters containing molten metal and floating slag. In accordance with the present invention, the known process has been further improved by sealing the tap opening as soon as possible after completion of the tap using a molten metal-destructive closure, then tilting the melting vessel while bubbling gas through the porous elements located in the immediate vicinity of the tap opening, observe the appearance of the slag pieces, and when the first slag appears, the drain opening is closed with a new closure body, then the tilt tank is tilted to its initial position.

According to a possible embodiment of the process according to the invention, it is expedient to remove the hydraulically actuated closing body directly from the drain opening at the start of the emptying operation.

According to a further preferred embodiment of the process according to the invention, a predetermined amount of gas, preferably 1-3 Nm ³ / h, is continuously bubbled through the porous elements into the melting vessel and this amount of gas is preferably increased to 5-10 Nm ³ / h during the tap.

The process according to the invention is carried out by means of a device in which the porous elements in the melting vessel have at least one elongated segment, preferably rectangular in cross section, which is connected to the gas distribution chamber on the cooler side and is connected to the gas source through the chamber pipeline. releasably secured to the swivel arm.

According to a preferred embodiment of the device implementing the method, the pivoting arm support member is attached to-21

187 104, and a pin formed on the front face of the support member frictionally engages with a bore formed at the rear of the closure body.

According to a further preferred embodiment, the concave rear surface of the support member is connected to the tilt arm via a convex face plate. This allows the closure body to be at an angle to the longitudinal axis of the tap opening and provides a central fit of the closure body to the tap opening with variable outline during wear.

It is also preferred that the closure body be of a truncated cone with a tapered end and a bore at the thicker end. This facilitates unhindered access of the closure body to the drain opening.

It is also desirable to have an embodiment in which the closure body made of wood, preferably pine, is partially covered with a heat-resistant layer. This prevents premature burning of the closure.

According to an improved embodiment of the device for carrying out the method according to the invention, it is advantageous to have a porous element on both sides of the tap opening about the axis of the tap opening. half a meter away. This facilitates the efficient use of the injected gas.

Further, the gas source is preferably a source of argon, nitrogen or carbon dioxide.

The process according to the invention and the structure carrying out the process have the following new advantageous effects:

The perfect separation of the molten metal and the slag floating on top is achieved from the beginning to the end of the tap. In the case of a two-stage operation for the pouring pan, there is no intermediate mixing of metal and removal and separation of the slag layer from the second tap, thus saving time. The harmful phosphorus content of the drained metal has been shown to be significantly reduced, and the consumption of refractory material in the smelting tank has been reduced by about 10%.

The process of the invention and the embodiment thereof will be described in more detail below with reference to the accompanying drawings. In the drawing it is

Fig. 1 is an exemplary embodiment of a device for emptying a tilting metallic melting vessel and a cross-sectional view of a portion of the melting vessel;

Fig. 2 is an enlarged sectional view of the structure of Fig. 1, and a

Figure 3 is a view of the tap opening and its immediate surroundings from the inside of the melting vessel.

As shown in Fig. 1, the opening 2 of the melting vessel 1 is closed by a closing body 3. The closing body 3 is mounted on a pivoting arm 4 pivoting about an axis 5 fixed on the wall of the tapping opening 2, and the pivoting arm 4 is provided with a stop 6. The counter piece 6, not shown in the drawing, is located on the wall of the container 1. The rocker arm 4 is connected via a fork 9 and a bar 8 to a hydraulic cylinder 7 operable in both directions, which is pivotally mounted on the wall of the melting vessel 1. In the present embodiment, the closure body 3 is of a truncated cone, the narrower end of which is slightly bevelled. At the thicker end of the truncated cone a cylindrical bore 14 is formed, in which also a cylindrical pin formed at the end of the pivot arm 4 is fitted (see Fig. 2). The hole 3 of the closure body is pressed against the tap by its bore 14. Preferably, the closure body 3 is made of a cheap, machine-made and relatively soft material such as wood, preferably pine. To make it more resistant to high temperatures, the surface of the barrier body 3 is partially covered with a heat resistant layer. As shown in Figure 3, a porous member 10 is provided on either side of the tap opening 2. The optimum location of these elements should be determined experimentally for each melter. In one embodiment, in which a 150 ton steel converter is used, the above-mentioned beneficial effects are achieved when the porous elements 10 are about a distance from the axis of the tap opening 2. They were placed at 0.5m. The porous elements required for the present invention are known per se, for example from Luxembourg Patent Nos. 82,552, 82,553, 82,554. The elements 10 are composed of adjacent oblong segments of rectangular cross-section surrounded by a metal casing. To the cooler side of the elements 10 is welded a gas distribution chamber 11, which is connected by a pipeline 12 to a gas source Γ3. The gaseous medium is uniformly circulated through the segments of the element 10, causing the gas to be fan-dispersed inside the container.

Instead of rigidly connecting the pin to the rocker arm 4 as shown in Figure 1, the solution shown in Figure 2 may be used. In such a preferred embodiment of the device according to the invention, a base plate 16 with a convex face is welded to the tube 20 attached to the end of the rocker arm 4. The screw 18 extending through the central bore of the base plate 16 engages with a concave back surface support member 15 having a stopper bearing pin formed on its face plate. The support 15 and the base plate 16 are retained by a spring 17 mounted on the screw 18, with one end resting on the rear surface of the base plate 16 and the other end resting on the washer 19 also located on the screw 18. The design of the bracket 15 and the base plate 16 allows an angle to the longitudinal axis of the closure body 3 which ensures a perfect fit between the closure body 3 and the tap hole 2 with variable contour.

The structure of the invention operates as follows:

During the melting process, the cylinder 7 depresses the rod 8 as shown in Fig. 1, thereby closing the mouth of the tap opening 2 with a locking body 3 through a fork 9 and a flap 4. It is advantageous for the drain opening to remain permanently closed except for the tap time, as this reduces heat loss and prevents sparks or slag from leaving the melting tank 1 through the tap opening 2 during the melting period. Prior to tilting the melting vessel 1, the cylinder 7 pulls the rocker arm 4 through the rod 8 through the fork 9 until the stop 6 abuts on the counter piece mounted on the side of the melting vessel 1. The closing body 3 itself remains in the tapping opening 2. The molten metal mass is the bil3 of the melting vessel 1

187 104 enters the tapping opening 2 and comes into contact with the closing body 3, which it burns for a few seconds. By this time, the tank is tilted at an angle so that only the molten metal enters the drain opening 2 and its immediate vicinity. Due to the continuous flow of strong gas bubbles, a vortex-free and slag-free circle is formed above the tap opening, so that only melted pure steel flows out of the tap opening 2. Meanwhile, another closure body 3 is placed on the end of the rocker arm 4 and toward the end of the tap when the first slag is detected - which can be detected by eye or optical detectors, magnetic detectors, etc. This can be done by actuating the cylinder 7 to introduce the new closure body 3 into the mouth of the tap opening 2. Due to the small weight of the closure body 3, the closure is extremely fast and, being made of a relatively soft material, it can take on the shape of the mouth of the tap opening. The hermetic closure of the tap opening 2 is provided by the self-adjusting fastening of the closing body 3 on the swinging lever 4.

The gas blown into the melting vessel is usually an inert gas such as argon, nitrogen or carbon dioxide. During the melting period, a gas supply of 2-3 Nm ³ / h is sufficient to prevent the porous elements from blocking. To eliminate the vortexes during the tap, this amount of gas is increased to 5-10 Nm ³ / hr. It is noted that blowing larger amounts of gas is unnecessary and harmful as it causes the molten metal to mix with the slag and thereby also feed slag into the tap opening 2. When adjusting the amount of gas, it was observed that the yield of ferro-manganese increased by 3-7% in the case of semi-soaked steels, with an average saving of 0.35 kg / tonne in equivalent steels. Similarly, the rejection rate due to the high content of 0.025% P phosphorus decreased to less than half.

The method described and the device implementing it can also be applied to melting tanks which are of non-tilting design and have a tap opening at the bottom of the tank. Similarly, more than two porous elements may be placed, depending on the container and the result achieved, and the bubbled gas may be other than argon, nitrogen, and carbon dioxide.

Claims (10)

A method for emptying tilting metallurgical melting vessels, in particular steel converters, by tilting the melting vessel, tapping the molten metal through a tapping opening formed in the sidewall of the melting vessel, the sealing body is destroyed by means of molten metal and gas is bubbled through the porous elements in the immediate vicinity of the drainage port to observe the appearance of the pieces ⁵ and then, upon the first slag appearance, the drainage vessel is sealed by tilt to its starting position. 2. The method of implementing the method of claim 1, characterized in that the hydraulically actuated locking body is removed from the spout immediately upon commencement of the emptying operation. 3. The method of claim 1 embodiment ¹⁵ mode, wherein said gas is a certain value through the porous member on the inside of the melting tank volume, preferably 1-3 Nm ³ / hour continuously bubbled in the metal melt and this gas quantity tapping ²⁰ over a period of 5 to 10 Nm ³ / h. Structure 1-3. carrying out the method according to the preceding claims, characterized in that the outlet opening with the melting container sidewall (1), (2), at least one porous member (10) and cooperating ²⁵ csapolónyílással (2), said closure body (3), wherein arranged in the furnace container wall (1) porous the element (10) having at least one elongated segment, preferably rectangular in cross section, which is connected to the gas distribution chamber ³⁰ (11) with its cooler side, and the chamber (11) is connected to the gas source (13) by pipeline (12); is mounted releasably on an actuated tilting lever (4). An embodiment of the device according to claim 4, characterized in that a support member (15) is connected to the pivot arm (4), the end of which is provided with a pin formed by a bore (14) at the rear of the closure body (3). An embodiment of the device according to claim 5, characterized in that the concave rear surface of the support member (15) is connected to the tilt arm (4) to allow movement over a convex face plate (16). A rocky configuration according to claim 4 or 5, characterized in that the closure body (3) has a truncated cone with a bevel (14) at its tapered narrow end and a thicker end. An embodiment of the structure according to claim 7, characterized in that the wooden, preferably pine wood, wooden body (3) is partially covered with a heat-resistant layer. An embodiment of the device according to claim 4, characterized in that a porous element (10) is located on both sides of the tap opening (2), preferably half a meter from its axis. 10. The structure of claim 4, wherein the gas source (13) is a source of argon, nitrogen, or carbon dioxide. 3 pieces of figure