SU905284A1 - Method for stopping blast furnace with gas ignition on the grate - Google Patents

Description

one

The invention relates to ferrous metallurgy, in particular, to methods for stopping and blowing out a blast furnace after an overhaul.

There is a known method for stopping and blowing out a blast furnace after an overhaul of a discharge UI, which includes loading the blowing mixture and charging it with backfill from granulated slag or sinter l.

The disadvantage of the method is that the order and loading time of the charging mixture are ad hoc. This method does not guarantee successful blowing of the furnace. The blown furnace was sometimes complicated due to burnout of air lances.

There is a method of stopping a blast furnace with gas ignition at the top, including loading idle coke feeds, lowering the surface of the charge and loading backfill from small ore on it.

The number of idle coke feeds and the time of their loading into the furnace is calculated

so that at the time of stopping the coke filled the forge and the shoulder pads. The amount of coke charged is determined in order to ensure a good thermal state of the furnace during {blown off Ul. .

The disadvantage of this method is that the filling materials fall into the central part of the embankment surface. Small materials caught in the axial part of the furnace

10 backfilling (ore or granulated slag) impairs gas permeability in the axial part of the charge column; when blowing, respectively, it slows down the process of restoring the normal distribution of the gas flow along the furnace radius, i.e. prevent it from forced blowing.

When loading the backfill on the trimmed surface of the materials of the blowing-off sheets 20, distributed in accordance with the feeds in the form of coke and agglomerate of small thickness and weakly expressed layers, the process of deformation is even

The charge and separate displacement of coke into the axial part of the furnace is poorly developed; as a result, a significant amount of agglomerate and waste materials fall into the axial part of the furnace along with coke.

The disadvantage of this method is the premature consumption of the first idle innings of the charging mixture even when the furnace is stopped.

The purpose of the invention is to increase the gas permeability of the axial zone, saving coke and forcing the blowing.

The goal is achieved by the fact that in the method of stopping a blast furnace with gas ignition at the furnace head, including loading the lightweight charge, idle coke feeds, lowering the charge surface and loading fine ore backfill on it, stopping the feed, blow the layer to the charge surface before loading the backfill coke with a height of 0.4 - 0.9 m, and the flow of blowing is stopped when lowering the first idle feed to the level of a slash.

Iron ore materials (sinter, ore) are used as backfill material. The composition of the secondary charge is calculated taking into account the backfill materials and the coke layer under it.

When charging the coke layer to the coke bed, the coke, as a lighter material, is displaced from the periphery to the central part of the furnace and the bulk of the backfill is located in the peripheral ring.

The coke layer, which is a large and light material, has a slight internal friction and, as a result, is easily transferred to the axial portion of the furnace when a heavy iron ore filling material is struck. The greater the proportion of backfill materials, the greater the strength and, accordingly, the effect of coke displacement. Granulated slag is not very suitable as a backfill material due to its penetration into the axial part of the furnace due to its low bulk density.

It is known that after stopping the furnace, the resulting gases mainly pass along the walls of the masonry. According to the proposed method, the bedding is preferably located near the walls of the masonry so as to maximize the resistance of the passage to gases at the periphery.

The location of the filling in the form of a peripheral ring has a number of advantages over its distribution over the entire surface of the filling, namely

increase in gas permeability in the axial part of the charge column, which accelerates the process of restoring the normal distribution of the gas flow

along the radius of the furnace during its forced blowing and exclusion of the possibility of blocking the hearth due to the absence of ore filling materials in the axial part of the furnace. Lack of materials for-

the bulking in the axial part ensures more favorable conditions for the penetration of the gas flow to the furnace axis and improves the processes of heat exchange and recovery in the axial zone. Such a distribution

5, the division of materials and gas flow makes it possible to force the blowing of the furnace, since in the blowing period the furnace operates at reduced parameters to blow and this creates additional difficulties for gas penetration to the furnace axis and heating of materials in the axial zone.

In the case of the approach of insufficiently prepared backfill materials to the lower part of the furnace, the possibility of blocking the central part of the hearth is eliminated. In addition, if the lateral ring is located in the form of a peripheral ring, its total amount can be reduced without damage, i.e., without increasing gas content and deteriorating conditions for repair work on the top plate. The decrease in the amount of backfill, in turn, is favorably reflected when the furnace is blown.

5 1

The most suitable material for backfilling is an agglomerate having a sufficiently large bulk density, allowing the layer of coke to be mixed in the axial portion of the furnace. The advantages of agglomerate as a backfill material compared to raw ore are more favorable particle size distribution, better recoverability and self-fusibility.

The thickness of the coke layer (0.4 -0.9 m) loaded under the filling is chosen in accordance with the small thickness of the filling.

0 Increasing the height of the coke layer under filling more than 0, 9 m is impractical, since an excessive concentration of an additional cocker in the upper part of the charge column will lead in general to a re-consumption of coke. With a coke layer of less than 0.4 m, inconsistencies between the volumes of coke and backfill, the concentration of backfill in the peripheral ring is less pronounced and the efficiency of the process is reduced. Concentration of the first idle supply of additional coke to the blown charge at the time of stopping the furnace in the steam eliminates the possibility of their premature consumption when the furnace is stopped. the central part of the pair, as it fits into the pair, being displaced to the axial part of the furnace due to the loading on it of the next innings of the intake batch, which include t iron ore materials. The dispersion of the remaining idle feeds of additional coke in the blowing mixture in the lower half of the mine, in turn, improves the gas permeability of the lower part of the charge column and is well reflected in the process of restoring the normal distribution of the gas flow when the furnace is blown. FIG. 1 shows the layout of the idle feeds of coke of the blower charge, the coke layer under the bed and its materials in the stopped furnace; .on FIG. 2 shows the flow of materials and the movement of gases during the blowing of the furnace. The proposed method for stopping a blast furnace for an overhaul with gas ignition at the furnace top and blowing it in is carried out as follows. The furnace is stopped and blown according to a previously developed program that includes calculation and placement of the blowing mixture in the furnace volume at the time of its stopping. 16 to 24 hours before the stoppage, the furnace that smelted pig iron was converted to smelting iron with a high silicon content of 0.8–1.2%. In calculating the charge, the basic slac is slightly reduced against the usual one in order to increase its stability and slow ductility. A diagram of the furnace profile is drawn up with a differentiated indication of the volume every 0.5 or 1, O m of its height (Fig. 1). Using such a scheme, calculations are simplified to select the optimal placement of the intake charge in the furnace volume, and it also achieves more precise control over the actual movement of the intake mixture when the furnace is stopped and blown. The diagram indicates the location. in the volume of the furnace at the time of its shutdown, in tem number and in the case of additional coke, loaded in the form of idle gear (Fig. 1). The first 40 - 50% of cold coke injections of the charge batch are loaded with concentration so that by the time of stopping this coke would find -. in a vapor joint, the rest are dispersed with the calculation of the location of idle feeds in the lower half of the furnace shaft. Following the blower charge, the coke is loaded as a separate layer 0.4–0.9 m thick, onto which, after stopping the furnace, backfill is loaded to create normal conditions for the repair work. The furnace is stopped with the lowering of the level of the charge mix and the ignition of gas at the furnace top. The furnace is blown at 50-7% of open tuyeres. Open and closed tuyeres alternate with a certain concentration of open tuyeres in the area of cast-iron tap-holes. In accordance with the developed technology provide for the forced increase of the parameters of the combined blowing in the process of blowing the furnace. At the initial moment of blowing the periphery of the furnace, the filling is sufficiently tightly closed, and the axial part of the charge column has a permeability of gas that permits activation of processes in. the central part of the hearth from the very beginning of blowing. At the same time, the first idle supply of additional coke of the blower charge, concentrated in the central part of the split, contributes to the activation of the central part of the forge. Favorably reflects on the gas permeability of the axial zone and the placement of a portion of the idle feed of additional blowdown coke in the lower half of the shaft. After the charge is resumed, backfilling while lowering down the presence of inclination of the walls of the mine departs from them, freeing the passage of gases and along the periphery (Fig. 2). The loading of the charge and backfill batch according to the proposed method allows to speed up the recovery of the operating parameters of the blast furnace process and significantly reduce the duration of the blowing period.

Example. According to the proposed method, a furnace with a volume of 2000 m of the Cherepovetsky Metallurgical Plant was stopped and blown out after an overhaul of 3 bits. For stopping and blowing in the furnace, a technological program was developed, including the calculation of the intake charge with idle coke feeds and their placement in the furnace volume.

The furnace produced pig iron with a silicon content of 0.4-0.7% and basicity of slag CaO / 5lOp 0.96 1, O4. 20 h before stopping, the furnace was transferred to smelting iron with a silicon content of 0.8–1.2% with a basicity of slag CaO / SiO 0.92– 0.99. For 4 hours and 20 minutes before the stop, another double feed was loaded with 11.1 tons of coke each. The following 3 blank feeds were dispersed in 5.3 and 7 innings, respectively. Fia intake batch loaded coke in the amount of 32.9t which was placed in a separate layer on top of the charge.

The loading order of the charging mixture is given in the table.

About 2 hours before the shutdown, the supply of natural gas and oxygen to the furnace was stopped and the level of filling started to be lowered. Stopping the stove was forced.

A filling layer consisting of 93 tons of sinter and 10 tons of ore was loaded onto the pubescent surface of the backfill consisting of a layer of coke. The charge level after loading backfill on the right probe 6.5 on the left 6.0 m.

The first two coke feeds of the blower charge are concentrated at the level of the kiln flue; The height of the coke layer, which was loaded after the charging mixture was about 0.6 m (Fig. 1).

When inspecting the backfill surface after stopping the furnace, it was established that the central part of the charge surface almost completely consisted of coke, and the iron ore filling materials were dissolved. in the peripheral ring. The gas burned steadily directly above the surface of the charge, heights

the flame was small, which provided normal conditions for repair work.

The furnace was inflated at 6 closed tuyeres from 2O with simultaneous reloading of the furnace with the charge to the operating level.

After 1, 5 hours after blowing, the first release was opened and 136 tons of pig iron with a silicon content of 1.19% and 1 slag bucket with a CaO / Si On content of 0.87 were produced.

The discharge of charge resumed immediately after blowing. The furnace was blown in force with an even gathering of charge materials; there were no cases of burnout of air tuyeres.

Due to the use of the proposed method, the duration of the blowing period is reduced by 20–24 h, coke saving is obtained, and additional cast iron is melted.

Claims (2)

The advantages of the proposed method for stopping a blast furnace for major repairs with gas ignition at the furnace head and its blowing are shonal separation of the charging mixture with filling in the furnace volume, which ensures an increased gas permeability of the column of charge materials, especially in its axial part, uniform heating of the mixture during blowing and economical fuel consumption. Using the proposed method makes it possible to force the blowing of the furnace, shorten the blowing period, obtain an increase in the production of pig iron, and save coke. Claim method of stopping a blast furnace with gas ignition at a pit head, including loading a lightweight charge, 4 idle feeds of coke, lowering the surface of the charge and loading backfill from shallow ore, stopping the flow of blowing, characterized in that in order to ensure gas flow in the axial zone , saving coke and forcing the blowing, a layer of coke with a height of 0.4-0.9 m is loaded onto the surface of the charge before loading, and the flow of blowing is stopped when lowering the first idle feed to the level of steam. Sources and forms taken into account during the examination 1. Metallurg, 1968, No. 7, p. 7-9. 2.Typova technological instructions for domain production. Dnipropetrovsk, 1977, p. 108-130. Uroven mound (1.75 and Backfilling Ho / 1psty feed coke Cast iron axis / 1etc