SU1629325A1 - Method of reconditioning of lining during steelmaking converter campaign - Google Patents

Abstract

This invention relates to the steel industry. The purpose of the invention is to increase the durability of the lining by creating an optimal period for carrying out torch gunning with heating of scrap metal and reducing the consumption of iron. Flare gunning (FT) is carried out after wear of the lining at 40-50%. The FT operations of the open areas of the lining are performed with simultaneous heating of the scrap with the FT operations of the bottom part of the lining before loading the scrap metal (m) into the converter without heating it. The ratio of the number of FT5 operations carried out with heating and without heating M is maintained equal to (185-2); 1, 1 silt., 2 tons abl,

Description

The invention relates to ferrous metallurgy, and more specifically to methods for repairing the lining of converters.

The purpose of the invention is to increase the durability of the lining by creating an optimal period for carrying out flare gunning with heating of scrap metal and reducing the consumption of pig iron,

The drawing shows a graph explaining the calculation results.

Flare gunning of the lining of the steelmaking converter is carried out after it is worn by 40-50% s. At the same time, the gunning of open areas of the lining is alternated with simultaneous heating of the scrap with the gunning operations of the bottom part of the lining before loading into the converter of scrap without heating it. The ratio of the number of torch shotcrete operations with simultaneous heating of scrap and without heating of scrap is maintained at (1, 5-2) 1.

The start of the lining recovery period, during which the scrap metal is preheated during the torch shotcrete, is chosen on the basis of the following considerations. Lining wear in the course of a steelmaking converter’s campaign is characterized by a change in the mass of the worked layer in the most wear part of the lining - cylindrical 5 The converter’s operating period ends when 85% of the lining weight in the cylindrical part in the bushing.

changes and takes the current values of g,

In the course of the converter’s campaign, the mass of the lining layer being operated is the same for smelting and depends on the planned number of heats N PL per campaign:, Of 85 tz

(nVPA- - -yyyyy

TCs - lining mass cylindrical

Which part of the converter, the Current radius of the converter is determined by the expression:

AND

r2 + (r-r2) - - r „+ | ira, c r

about a.c o mpl

where gass is the radius of the converter lining to the reinforcing layer, MJ N is the current number of heats in the course of the campaign.

Under accepted assumptions, calculations were performed for a 300-ton converter, characterized by the following parameters

g, 3.25 m; rQ.e Go + 5, 15 m

- the thickness of the working layer fu .-, - 0.9 terovki; ,

±

m

Ty 300000 kg; .

The results of the calculation are shown in a graph (drawing), which shows the change in the initial radius and the relative - 7SH "current lining radius in the course of a campaign with paired periods of liner wear depending on the change in weight of the lining layer to be operated. -Gb | z0%, and (ui) r; -r0 / 20% - change in the initial radius of the lining when the weight of the lining layer is changed by 30 and 20% of the initial mass (TC), respectively.

As can be seen from the graph, an intensive change in the radius of the lining occurs at the beginning of the campaign and stabilizes after the wear of the lining by about 40-50%. Therefore, there is a need to limit the limits of wear of the lining, at which gunning operations begin. The choice of rational values of wear of the lining is given in table. one.

Assuming that uniform lining wear will occur around the circumference of the cylindrical part, other things being equal, an increase in the volume of the cylindrical part can be determined depending on the wear of the working lining layer.

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As can be seen from the table. 1, when the lining is worn by 40% by weight, the volume of the internal cavity in the cylindrical part of the converter increases by almost one and a half times. When the lower limit of the lining wear is reduced to less than 40%, the free volume of the converter decreases, resulting in an increase in the knockout of high-temperature gases through the throat, the amount of heat loss increases, and the heating efficiency of the scrap metal during torch shotcrete decreases.

Increasing the upper boundary value of liner wear by more than 50%, after which scrap metal is preheated during flare gunning, is impractical because it reduces the total number of torch-gunning operations that heat the shotcrete torch to heat scrap, which reduces the amount of savings cast iron for the campaign.

The ratio of the number of torch shotcrete operations carried out with and without heating scrap metal is selected from the following considerations. The area of the surface of the lining covered with scrap during the shotcrete process and inaccessible to the application of the shotcrete is approximately half the area of the remaining repaired areas of the lining. These closed areas of the lining at the end of the gunning process are subject to significant wear due to local melting of the surfaces of the scrap metal and the lining, since for high-temperature products of the gunning torch and the surfaces of scrap metal and lining the first condition is realized:

tn. r «e CH.G tM and t qp temperatures of the combustion products of the shotcrete, scrap metal surfaces and

0

 g-b

Ugg

lining, respectively, 1650-1700 ° C,

Applying more refractory material (shotcrete) to the lining areas of the lining than the other parts of the lining is not rational, since large local burnouts on the applied gunning itself have to result in the gunning operation, which becomes unprofitable economic considerations, as the consumption of gunning mass per campaign increases. Let us call: the technological gunning mass is the gunning mass, which is spent on restoring worn areas of the lining and heating the scrap metal, repair gunning mass is the gunning mass, which is spent on restoring the surface areas of the lining covered with scrap metal. Therefore, it is advisable

After the slag has been drained and the metal has been discharged, the converter is placed in a vertical position, and a shotcrete tuyere is introduced into the cavity, into which the shotcrete mass is supplied, which consists of a mixture of, for example, dolomite and coke powder oxygen. When the shotcrete tuyere jets of shotcrete mass and oxygen outflow from the nozzles, the dolomite shotcrete mass is applied to the lining areas that can be closed to keep the technological and repair shotcrete mass flowed on each one-j5 with the breakthrough during its heating in the flare gunning unit. flare gunning operations. After the end of the gunning process, scrap metal and molten iron are loaded into the converter and converter melting is carried out. Then, after slag discharge and steel production into the converter cavity,

nakov.

We assume that the total consumption of shotcrete for the campaign does not exceed the mass / refractory of the lining, take its consumption for the shotcrete of the 300-ton converter 500 tons and the total number of shot-cutting operations equal to 100, while taking the reduction of the consumption of iron for the shotcrete smelting by 10 tons 25. Let us determine the change in the mass of cast iron consumed for the repair gunning mass, depending on the change in the ratio of the number of operations, torch load the scrap metal into smelting, set the converter to a vertical position and to the surface of the scrap metal. t water gunning lance. The change in height of the shotcrete tuyere when the scrap metal is heated is determined by taking into account its bulk mass and control after the lining wear by 40-50%.

After the slag has been drained and the metal has been discharged, the converter is placed in a vertical position, and a shotcrete tuyere is introduced into the cavity, into which the shotcrete mass is supplied, which consists of a mixture of, for example, dolomite and coke powder oxygen. When the shotcrete tuyere jets of shotcrete mass and oxygen outflow from the nozzles, the dolomite shotcrete mass is applied to the lining areas covered with metal in the process of its heating during the subsequent flare operation, scrap is melted, the converter is placed in a vertical position, and t gunny-tuyere. The change in height of the gunning tuyere when the scrap metal is heated is set taking into account its bulk mass and is controlled by

first shotcrete, carried out with and without heating by the driver of the distributor for scrap metal (tab. 2).

As can be seen from the table. 2, reducing the ratio of the number of torch gunning operations to less than 1.5 is impractical because. the weight of the pig iron is reduced by the gunning mass, resulting in a decrease in the amount of pig iron saved

campaign. As the upper temperature increases, heat transfer slows down. When outwrapping of shotcrete masses and oxygen from the nozzles of the gunning tuyere, the process of applying the gunning mass to the lining sections of the cylindrical and conical (throat) parts of the converter begins. After the gunning process is complete, cast iron is loaded into the converter and the converter melting is carried out . During the lining recovery period, the lining operations alternate the shotcrete operations, maintaining the ratio of the number of flare gunning operations supplied with and without heating the scrap metal to (1.5-2}: b

During the campaign, in steel production, operational situations depending on the characteristics of cast iron, the ratio of torch gunning operations to more than 2.0, dramatically increases the dynamics of cast iron mass by reducing the consumption of repair gunning mass and there is an increase in wear of the lining sections covered with scrap metal, which may lead to premature stopping of the converter for cold repair. The method is carried out as follows.

During the converter’s campaign for steel production, the maintenance personnel controlling lining wear gives the command to pre-heat scrap metal during torch gunning 55

five

blue, located on the central control panel (CPU).

In the initial period of the torch gunning process, it is advisable to move the jets of burning gunning torch to the scrap metal surface no closer than 1.5 m, since gas burning is difficult near the cold scrap metal surface and, therefore, the amount of working converters in the proposed method can be considered portioned. loading scrap into the converter. So, for example, after lining wear by 40%, half the mass of scrap metal for smelting can be heated during flare shotcrete. Reducing the mass of heated scrap metal during shotcrete, corresponding to lining wear of less than 40%, is irrational, as the mass fraction of cold scrap metal for smelting increases, reduces steel production efficiency

Example. The method is carried out during hot repairs during the restoration of the lining of a 300-ton converter for steelmaking. During the campaign, the service personnel found that in the area of trunnion zones, notches and loading of the charge metal, the lining wear is approximately 40%. The monitoring is carried out on the activated lining working layers visually or by a laser interferrometer. The lining recovery period begins . During the recovery period, 100 flare gunning operations are required. Of these, 60 operations with the heating of scrap metal. The consumption of gunning mass per campaign is 500 tons.

The first torch gunning operation without heating the scrap metal is carried out, in which the guncrete coating is applied to areas that are inaccessible for application during scraping with heating of scrap metal. During the converter melting period, the distributor operator commands the operators of the charge yard and the mixing compartment to increase the scrap metal weight and reduce the cast iron mass by 10 tons, respectively. The ordered charge materials are ready after the two converter melts after the first flare shot operation. Flare shotcrete are heated with scrap metal.

During the campaign, during the rebuilding of the lining, torch gunning operations alternate

The mode of operation of the converter during the campaign after wear of the lining is 40-50% from the point of view of carrying out the operation

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ABOUT

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Flare gun mounts can be represented as a scheme:

TV - TH - TV - TH - TH, where TB - TH is shotcrete without heating and with heating of scrap metal, respectively.

When implementing the above scheme, the gunning after each converter melting is not necessary, since the resistance of the applied gunning coating, depending on the mode of gunning, is 3-6 heats. When rebuilding the lining in the course of a steelmaking converter campaign in accordance with the above scheme, the ratio of gunning operations to heating (T) and without heating (T) of scrap metal is 1.5: 1. In the course of a campaign, depending on the operating conditions of the converter shop, the ratio of gunning operations with and without heating of scrap metal should be maintained within (l, 5-2): l. For example, the total number of operations is 100, while we accept a reduction in the consumption of cast iron per gunned melt by 10 tons. According to the proposed ratios (1.5-2): 1, the number of operations with heating of scrap metal and without heating it should be within Lt 60:40 to 67:33 or 66: 34. After the lining is worn by 40-50% from the point of view of carrying out torch gunning operations, the implementation of alternation schemes can be different. It is important that the proposed ratio be maintained in general and within the limits of the resistance of the applied shotcrete.

The applied gunning coating during the lining recovery period according to the proposed method under the conditions of frequent heat shifts undergoes less damage (chipping, cracking) due to more uniform operation and frontal wear, which ensures a long service life and protection from the main lining of the converter ,

Thus, the proposed method of lining recovery allows increasing lining durability by 10-15% by creating an optimal period for conducting torch gunning with heating of scrap metal, which allows to utilize part of the heat of the gunning flare lost with exhaust gases, due to its use heat balance of the converter smelting and reduce the consumption of cast iron for the gunned smelting by 10 tons.

Claims (1)

Invention Formula A method of restoring the lining in the course of a steelmaking converter campaign, including carrying out torch gunning of open areas of the lining after loading the scrap metal into the converter with simultaneous heating of the scrap metal, characterized in that, in order to increase the durability of the lining by creating an optimal period of 11.6 23.3 34.9 46.6 58.2 69.6 The change in mass of iron consumed for repair gunning mass, t / t 932510 flaring gunning with heating of scrap metal and reducing cast iron consumption, flaring gunning is carried out after wear of the lining at 40-50 &, the lower part of the lining is additionally shot before loading into the converter of scrap metal without heating it, alternating with the operation of jigging open areas of the lining with simultaneous heating of scrap with gunning operations of the lower part of the lining, and the ratio of the number of flare gunning operations with simultaneous heating of scrap metal and without heating ma is maintained at (1.5-2): 1 15 Table 1 Table 2 2.0 3.0 3.88 5.14 4-5 but  i thirty 15 60 tsr.,%