ES2321071T3 - PROCEDURE TO STEEL AGITATE. - Google Patents

Abstract

Said invention relates to methods for the out-of-furnace processing of metal for the iron and steel industry. Said invention makes it possible to expand an active zone of coverage of metal volume by gas or a gas-powder mixture, thereby reducing the time required for obtaining a homogenised composition of metal without increasing the quantity of supplied gas, i.e. to solve the problem of the intensified steel feeling by gas or gas-powder bubbling. The inventive method for feeling steel consists in blowing steel from the bottom by gas or a gas-powder mixture through at least two designed blowdown devices diametrically arranged on the opposite sides of a ladle. The bubbling is carried out alternatively through the devices arranged on the opposite sides of the ladle, a pressure for preventing the flowing of metal in the device which is not used at given moment being maintained therein. The alternative operational time of the blowdown devices is increased proportionally to the increase of steel in the ladle, the volume of supplied gas being unchangeable when the gas or gas-powder mixture supply is switched from one blowdown device to another.

Description

Procedure for stirring steel.

The invention relates to methods for liquid metal treatment in a boiler outside the oven in Black malleable metallurgy.

It is known that during steel treatment out of the oven inert gas and technological dust are conducted to the casting or through blow molds submerged in the laundry or through special plugs arranged at the bottom of the boiler.

The intensification of the agitation process of metal, which allows a reduction in processing time of steel, has a great importance in the treatment process Metal out of the oven in a boiler. The homogenization of the casting accelerates the stabilization and elimination processes of nonmetallic inclusions as well as desulfurization and dephosphoryization of steel, which guarantees the achievement of Boiler metallurgy objectives.

A procedure for the intensification of metal stirring in a boiler through the increase in gas flow for blowing. In the procedure known, the gas is fed through a blow mold of the type of "hollow plug bar" and to prevent the injection of metal in the case of high gas feed a front piece (screen) in the form of a disc in the stopper bar (see, for example, Stahl, No. 12, 1999, pages 17-19).

The main drawback of the procedure is the attempt to solve the task of intensifying the metal agitation through the lifting of the feed of gas. In addition, in this case, most of the metal in the boiler it is not affected by the movement of agitation, especially not in Your bottom areas. In general, the foregoing reduces the effectiveness of the known procedure in solving all the task.

In addition, a procedure for the stirring of steel in a boiler, which includes the introduction of a gas soluble in steel, which separates during treatment to vacuum in the form of very small bubbles floating on the surface of the casting bath in steel (as well as in water of soda), (see, for example, "Stahlerzeugung an der Schwelle des Dritten Jahrtausends ", Annex 7 to the magazine" Neuigkeiten der Schwarzmetallurgie im Ausland ", 2000, page 25).

The main drawback of the procedure known lies in its obvious rise, among other things, due to the need to apply a circulation treatment to empty (NK-PERM process of the Firm "Nippon Kokan ").

A procedure for stirring is also known. steel in a boiler through its agitation by means of forces electromagnetic (see, for example, "Injektionsmetallurgie", English translation, published by Sidorenko M. B. Moscow, "Metallurgie", 1986, page 90).

The main drawback of this procedure are the high costs of the equipment used with an effect of relatively reduced agitation.

A procedure for stirring is also known. steel in a boiler, in which the blowing is performed alternate from different blowing devices (JP-A-06-235018).

The essential inconvenience of this procedure It is the irregular agitation of the steel mass.

In addition, a procedure for stirring is known. steel in a boiler, which comprises blowing through the steel from below by means of a gas or a mixture of gas and dust through blowing devices arranged at the bottom of the bathroom laundry, at least one of which is displaced outside the center of the boiler (see, for example, the indicated source "Injektionsmetallurgie", pages 142-143 and figure 12). Although in performing the known procedure, prefers the feed of the gas or the mixture of gas and dust to through special plugs at the bottom of the boiler, your realization does not exclude the feeding of the indicated components through a submerged blow nozzle (nozzles of blown).

This known procedure to stir metal in a boiler through the gas supply or a mixture of Gas and dust is the closest, according to its characteristics essential, to the process according to the invention and, therefore Therefore, it is considered as the closest state of the art.

An essential, peculiar inconvenience of Known procedure is as follows: in the course of blown through the steel by means of the gas or gas mixture and powder the metal is stirred irregularly over the volume of the boiler. Especially the areas of liquid metal, which are in the gas inlet or the mixture of gas and dust in the steel (more active zone), are subjected to a stirring movement intensive As the gas or gas mixture approaches and powder to the surface of the metal in the boiler, these are widened zones, travel (reducing speed) the upper layers of the wash bath and descend from the surface as currents weakened descendants. Obviously, this described image of Agitated metal movement reduces agitation effectiveness of steel, because it affects very slowly the entire volume of metal in the boiler and especially the bottom areas of the steel bath. In general, the proposed task of acceleration is not achieved of the homogenization of the metal composition. The process known requires a high gas application and especially time, which is not available to a sufficient extent in the technological process of current steel manufacturing.

The process according to the invention to stir metal in a boiler does not present the disadvantages mentioned. In this procedure, the area is essentially extended active inclusion of the volume of metal through the gas or the mixture of gas and dust. This leads to time reduction for the achievement of a homogenized metal composition without increase in the amount of gas fed, that is, that solves the technical task of agitation intensification of the steel in a boiler by means of blowing through the steel of a gas or a mixture of gas and dust.

The mentioned technical results are achieved because in the procedure to stir steel in a boiler, which it comprises blowing through the steel from below by means of a gas or a mixture of gas and dust through at least two devices of blowing provided, which are arranged on sides diametrically opposed boiler, according to the invention the blowing is performed alternately firstly through one of the blowing devices, which is arranged on one side of the boiler, and then through the other device of blown, which is located on the other side of the boiler. In this case, in the blowing device, through which it is not blown at that time, a pressure is maintained, which excludes the influx Metal in this device. The period of the change of operation between the blowing devices it increases as it Raise the mass of steel in the boiler. Gas volume supplied remains unchanged after switching the supply of gas or mixture of gas and dust from a device  from blow to the other.

The process according to the invention to stir metal in a boiler by blowing through the Gas steel or a mixture of gas and dust is explained in detail With the help of schematic drawings.

Figure 1 shows a boiler with metal, in which two blowing devices are provided as plugs at the bottom of the boiler. Figure 2 shows a similar boiler with two nozzle-shaped blowing devices of blowing. Figure 3 shows the view in the direction of arrow A according to figure 1. Figure 4 shows the view in the direction of arrow A according to figure 2. In this case, the boiler has at least two blowing devices.

The cast iron boiler 1 is full with liquid steel 2. At the bottom of the boiler (figure 1) are provided at least two blowing devices 3 on sides diametrically opposed boiler 1 (figure 3). The number of These devices may be older, but must be even. In the boiler 1 blow molds 4 can be provided arranged on diametrically opposite sides of the boiler 1. The number of molds Blowing may be higher, but must be even. The gas or the mixture of gas and dust 5 is fed to the boiler in each case to through plugs at the bottom of the boiler (figure 1) or through blow nozzles 4 (figure 2). The gas or the mixture of gas and dust They can be fed separately to the boiler. In this case, it increase the number of devices 3 (blow molds 4) to the next next even number. In figures 1 to 4 it is 6 represent the main currents of the metal with fine lines, that are configured during the feeding of the gas or the mixture of gas and dust on one side of the boiler. Those currents, which are configured during the switching of the blowing devices, they are represented with dotted lines 7. An elevation of the number of the caps 1 (blow nozzles 4) does not modify the essence or the effect achieved from the proposed procedure, but it rises additionally the intensification of the stirring of the steel, is say, that the effectiveness is raised (but at the same time complicates the design).

The procedure for stirring steel in A boiler is made as follows.

Steel 2 is poured into the boiler. necessary elements for the endowment, desulfurization or Dephosphoryization of steel are introduced into the steel through known procedures or as powder through the devices 3 (or 4) described, or through both procedures thereto weather.

The gas supply is switched on (mixture of gas and dust) 5 through plug 3 (blow mold 4), which found, for example, on the left side of figures 1 to 4. Inert gas is used, for example argon. As a result, it set the main streams in the metal casting, which are represent through lines 6. At this time, it remains a gas pressure in the cap 3 (in the blowing nozzle 4) on the opposite side of the boiler, which excludes the influx of steel in this plug. After a certain time (period) is modified the direction of the main currents of the metal in the bath of the boiler through gas supply (gas mixtures and powder) 5 through plug 3 (blow mold 4), which is arranged on the opposite side of the boiler (right on the Figures 1 to 4), in the opposite direction. The main currents of the metal in the casting bath begin to move as it represented through dotted line 7 in figures 1 to 4. A through the periodic change of the direction of movement of the metal streams 6 \ rightarrow 7 \ rightarrow 6 and so successively the agitation process is intensified essentially of metal As a result, in the course of a shorter time a more homogenized composition of the steel is obtained in the boiler, that is, that the proposed task is solved.

The address field period of the Gas supply (mixture of gas and dust) is determined in the practice. However, the periodicity of the indicated change rises with the lifting of the steel mass in the boiler, because only in this case the metal currents 6 and 7 have the form desired (shown in figures 1 and 2) and the change of direction of the gas supply (mixture of gas and dust) has an impact on minimum measure on its damping.

There is a period of change of address, which it is optimal for the predetermined operating conditions of the boiler A reduction in the duration of this is not recommended period, because zones of incomplete homogenization of the casting in the volume of steel. An elevation of the duration of this period and is determined by the rhythm General technological generation of steel.

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Example one

A "cold model" of a boiler 1 would have the dimensions shown in Figure 1. Water from the tap 2 has been filled in the boiler to a height of 430 mm. The boiler has been equipped with three platinum electrodes: one in the lower part of the boiler (water level distance 370 mm), one in the central part of the boiler (water level distance 220 mm) and one in the upper part of the boiler (distance from water level 60 mm), which have been previously calibrated in the tap water intervals - 0.1% by weight aqueous KCl solution. All three electrodes were spaced 55 mm from the inner wall of the boiler model. In addition, a portable electrode was planned, with which the homogenization of the solution in the boiler model centers was further evaluated,
at the bottom of the bottom, on the surface of the water as well as at the bottom joints and the walls of the boiler

A 20% KCl concentrate was prepared and descended on a thin rubber ball against the background of the model of boiler in the area near the wall of the boiler, which was placed at 90º of the devices 3. The ball was cut. In this case a concentration of 0.1% KCl in the water was adjusted through of 20% KCl concentrate after uniform distribution on the mass of water, at whose concentration the electrodes The use of the ball has an impact Minimal disturbing on the water bath.

The gas (air) was fed through the devices in the background in an amount of 6 l / min. In the case of a higher air supply, the formation regime was disturbed of blowing bubbles.

Under the indicated conditions and the blowing of air through a device 3 without change of direction is obtained, after 84 minutes, a homogeneous solution of 0.1% KCl in weigh. In this case, the solution was practically the same in all additional measured places over the entire mass of solution.

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Example 2

Under the conditions indicated in example 1, made an alternate air supply with a period of 30 seconds. In case of change of address, the amount of the air fed in 6 l / min. After 35 minutes it was obtained in the boiler model a homogeneous solution with concentration indicated above, that is, the time of stirring 2.4 times compared to Example 1.

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Example 3

Under the conditions indicated in Examples 1 and 2 an alternate air supply was carried out with a period of 20 seconds. After 60 minutes, a boiler was obtained in the boiler homogeneous solution with the concentration indicated above, is say, the stirring time was reduced 1.4 times compared with Example 1. At the end of the 60 minute stirring, areas with concentrations established in the volume of water greater and less than 0.1% of KCl in the water, which were not recorded by the main electrodes.

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Example 4

Under the conditions indicated in Examples 1 and 2, an alternate air supply was performed with a period of 20 seconds. After 80-87 minutes, a boiler was obtained in the boiler. homogeneous solution with the concentration indicated above, is that is, stirring time was reduced practically by comparison with Example 1. At the end of the stirring, areas with concentrations established in the volume of water greater and less than 0.1% of KCl in the water, which were not recorded by the main electrodes.

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Example 5

Under the conditions indicated in Examples 1 and 2, an alternate air supply was performed with a period of 40 seconds. After 55 minutes, a boiler was obtained in the boiler homogeneous solution with the concentration indicated above, is say, the stirring time was reduced 1.5 times compared with Example 1. The volume of water lacked areas with a KCl concentration, which differed from the concentration of 0.1% by weight of KCl.

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Example 6

Under the conditions indicated in Examples 1 and 2, an alternate air supply was performed with a period of 50 seconds. After 60 minutes, a boiler was obtained in the boiler homogeneous solution with the concentration indicated above, is say, the stirring time was reduced 1.4 times compared with Example 1. The volume of water lacked areas with a KCl concentration, which differed from the concentration of 0.1% by weight of KCl.

The process according to the invention for stirring steel in a boiler allows through a simple conduct of the procedure an essential intensification of the steel stirring process (a reduction in the time of realization) without a reduction in the quality of agitation.

Claims (1)

Method for stirring steel in a boiler, which comprises blowing through the steel from below by means of a gas or a mixture of gas and dust through at least two planned blowing devices, which are arranged on diametrically opposite sides of the boiler, characterized in that the blowing is performed alternately firstly through one of the blowing devices, which is arranged on one side of the boiler, and then through the other blowing device, which is located on the another side of the boiler, so that in the blowing device, through which it is not blown at that time, a pressure is maintained, which excludes the influx of metal into this device, so that the period of the change of operation between the blowing devices it rises as the mass of steel in the boiler increases and the volume of the gas supplied remains unchanged after the switching of the gas supply or of the mixture of gas and dust from one blowing device to the other.