SU1346938A1 - Method of removing slag from slag chamber in liquid state from steel-melting furnace and device for effecting same - Google Patents

Abstract

The invention relates to ferrous metallurgy, and more specifically to the liquid slag removal of a steel-smelting hearth furnace. The purpose of the invention is to increase the durability of the slag and increase the productivity of the furnace. The horizontal hearth 7 and the slopes 8 of the slag are made of small-sized limestone and iron oxide. The loading window 12 is made in the side wall 3 of the slag along the axis of the vertical channel 5. In the end wall 1 is placed, there are additional working taps 11 at different levels vertically. The lower working port 11 is 1 / 10-1 / 15 of the slope height from the bottom. Through the window 12 load concentrated on the slopes 8 and the hearth 7 flux mixture 13 in the amount of 1.5-5.0 kg per 1 kg of melted dust collected. A mixture of iron ore, lime and combustible material is used as a fluxing mixture. Combustible material is introduced in the amount of 0.5-5.0% of the total amount of the mixture. The slag level in the slag is varied in steps, partially discharging the slag through the workers' tracks. 11. The invention will improve the dust-collecting capacity of the slag, which will increase the durability of the regenerative nozzles and increase the productivity of the furnace. In addition, due to the protective action of the slopes and bottom, the durability of the slag will increase, and the flow of refractories will decrease. 2 sec. item f-ly, 1 ill. "Cl with 4 about: WITH with 00

Description

The invention relates to ferrous metallurgy, in particular to the production of steel in open-hearth and double-bath steel-smelting furnaces, and is intended to remove slag from sludge-making furnaces of steel-smelting furnaces formed from trapped smelting dust.

The purpose of the invention is to increase the durability of the slag and increase the productivity of the furnace.

The drawing shows a device that implements the proposed method, a longitudinal section.

The slag has face 1, a saddle 2 and side 3 walls and a bottom 4, made of the main refractory brick. A vertical channel 5 fits to the slag, and in the lower part of the slag it is made of fine limestone bath 6, consisting of bottom 7 and slopes 8. Slopes 8 and bottom 7 are covered with a cladding layer 9 of iron oxides. In the end wall 1, at the bottom 4 itself, there is one slag tap repair 10 and several slag tapes 11 located at different levels. - The lowest working bay 11 itself is located from the top of the bottom 4 at a distance of 1 / 10-1 / 15 of the slope height, 0.25-0.30 m, and all other working branches 11 - with a step of 0.065-0.195 m vertically in 2-3 p yes. In the side wall 3 of the slag is made along the axis of the vertical channel 5 loading window 12. On the side slope and bottom of the vertical channel concentrate flux mixture 13 in the form of a half truncated cone made of iron ore, limestone and combustible material in the amount required by 5- 15 heats. All this is done during the cold repair of the furnace.

Such a device of a slag and installation at the charging port of the charging mechanism, and for slag tap holes - bowls, allows the method of slag removal in the liquid state to be carried out. During the period of heating of the furnace and the first swimming trunks, the following processes take place in the slag. The limestone of the hearth 4 and the slopes 8 is fired and its surface layer is slagged with monolithic iron to form the inner surface of the bath due to the saturation of the iron oxides from the cladding layer 9. In addition, on the inclined surface of the truncated cone of the fluxing mixture 13, the low-melting slag melts and flows into the slag bath 6. The low-melting liquid slag film on the surface of the fluxing mixture 13 and the liquid slag mirror in the slag bath intensively absorb the refractory melting dust, deeply cleaning the high-temperature gases coming from the furnace working space to the regenerative nozzles, providing a high dust-collecting capacity of the slag. At the same time, the slag melting point in the slag is gradually increased. At the beginning of the furnace company, when temperatures

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slag mode is lower than usual, the total consumption of the flux mixture should be at least 2.5 kg per 1 kg of melting dust. In order for such an amount of flux mixture to melt in the slag, the content of combustible material in it must be at least 2.5%. As the slag is heated, the specific total consumption of the flux-containing mixture and the content of combustible material in it are reduced. The criterion for the correctness of the specific consumption of the flux mixture and the ratio of non-combustible components is to obtain the desired melting point of the slag in the slag, comparable to the average or minimum temperature of the slag. The criterion for the correct choice of the content of combustible material in the fluxing mixture is its almost complete melting in the slag-stone by the time of the next slag production and the loading of the next portion of the fluxing mixture. Starting from 6-16 heats from the beginning of the company, the furnace starts to systematically load the flux mixture after 1-6 heats. After approaching the level of liquid slag in the slag, to the highest slag pit begin proceeding to the systematic release of slag from the slag after 1-6 heats. As the upper part of the slopes 8 of the slag bath is worn out, it is successively transferred to the release of slag through working slag tap holes 11 located at a lower level. The kiln campaign is completed with the full release of slag from the slag through a repair tap located at the hearth itself.

According to the invention, in the end wall of the slag should be several tap holes located at different levels in height. At the beginning of the campaign, with a large amount of flux in the slag, the bath level of the molten slag is high. As slag accumulates, its descent takes place through the upper tap-hole. As a part of the flux located in the upper part of the slopes of the slag operates, the level of the slag bath decreases and the slag is released from the slag through the tap below. Such a transition from one notch to another is carried out throughout the whole company, every 3-4 tens heats. Workers in the end wall of the slag should be placed at different levels with a pitch in height that is a multiple of the thickness of a normal refractory brick (65 ml). The bottom hole of the slope is located at a height of 1 / 10-1 / 15 of the height of the slopes, so that a layer of liquid slag 250 mm deep and more needed to dissolve the refractory melting dust in it always remains below this tap hole.

If the lower melting workplace is at a distance less than 1/5 of the height of the slopes, it may be corroded; slag of the main slab of the hearth, as a result of which the amount of work during the repair of slag pottery may increase. With the position of the lower working notch in accordance with the specified limits, the walls and bottom of the slag will be practically “eternal, and the productivity of the furnace will be maximum. If the lower work tap is placed at a level higher than 1/10 of the slopes, the top layer of slag will be placed above the slopes made of the flux, while the slag wall material may dissolve in the slag, which will also cause an increase in the amount of work during the repair and consequently, a decrease in furnace performance. The mass of the slopes and, therefore, the height of the slopes in the slag is set such that they were enough for the whole campaign of the furnace. A letka, located at the bottom level of the slag, is used to discharge all the slag from the slag before stopping the furnace for cold repairs.

Concentrated loading of the flux mixture to the slope and hearth below the vertical channel, namely, to the zone of maximum sedimentation of melting dust and maximum temperatures in the slag, improves the dust collecting capacity of the slag and completely dissolves the melted dust due to the formation and continuous updating of the liquid slag layer on the inclined surface flux. The use of a fluxed mixture of ns iron ore and limestone provides it. Mp. from 1050 to 1150 ° C, and the introduction of a mixture of combustible material to the composition of the flux from 0.5 to 5% makes it possible to maintain the optimal rate of its melting under the most varied process conditions.

Thus, the minimum content of combustible material in the fluxing mixture should be at the minimum specific consumption of it and the maximum temperature regime of the slag, and the maximum content should be at diametrically opposite conditions. The expenditure of the flux mixture in the amount of 1.5 kg per I kg of trapped melting dust ensures the production of slag in the slag-stone with m. Pl. no more than 1300-1350 ° C, which is comparable with the average temperature in the slag. With a further increase in the consumption of the fluxing mixture to 5.0 kg per I kg of melting dust, the slag melting temperature in the slag is lowered to 1100-1150 ° C, which is lower than the minimum temperature in the slag during normal operation of the furnace. A further increase in the consumption of the fluxing mixture has virtually no effect on the melting point of the slag in the slagberry.

Partial production of liquid slag from the slag, usually in the amount of 20-80% of the liquid slag present in the slag, ensures a high dust-collecting capacity of the slag due to the constant preservation of the larger surface of the liquid slag. The change in the level of the liquid slag in the slag gradually increases the resistance of the refractory walls of the slag wall by

sequential operation of slopes of limestone slag bath. If such a quantity of limestone is laid in the slopes of a bath of sufficient height that is enough for the entire campaign of the furnace, the refractory side walls of the slag at the level of the bath will remain unchanged. Coal, coking or any other reducing agent may be used as a combustible material, but using coal is most preferable for economic reasons. It is possible that the use of fuel oil as a combustible material will lead to the suppression of dust formation when the flux is loaded into the slag.

5 Execution of the slopes and bottom of the slag bath from limestone increases the resistance of the refractory walls and bottom of the slag and reduces the consumption of the flux mixture to produce low-melting slag. Known to in the slopes of the slag performs a dual role:

First, it works as a refractory, and as it dissolves in the slag, it acts as a flux. A section on the slopes and bottom of the iron oxide layer during cold repair of the furnace provides an increase in their resistance due to

5 slagging, monolithing their surface layer in the first melts. The load on the slope and hearth below the vertical channel of the portion of the fluxing mixture of iron ore, limestone and combustible material during the cold repair of the furnace contributes to the formation of low-melting slag by the end of the heating of the furnace in such quantity that ensures complete dissolution of the refractory melting melted dust, starting from the first heat. Loading flux mixture at the rate of 5

5 heats provides for the formation of a protective, “dead” layer at the bottom of the bath, and loading it on the basis of 15 first heats provides for raising the liquid slag in the bath to the maximum level, up to the level of the upper working slag tap. Execution of the loading window in the side wall of the slag along the axis of the vertical channel provides loading of the fluxing mixture to the slope under the vertical channel, as provided for by the proposed method, with minimal dust emission. The location of several workers' branches at different levels from the bottom will allow the level of liquid slag in the slag-stone to change in a stepwise manner during the campaign and produce only part of the liquid slag.

d Using the proposed method of slag removal from the slag of the hearth furnace in the liquid state as compared with the known method provides an improvement in the slag slag's dust-collecting capacity and a reduction, and possibly even complete suppression

5 dust emission when loading the fluxing mixture, maintaining the regenerative nozzles in good condition until the end of the kiln campaign, which leads to high-performance furnace operation and fuel economy.

Increasing the durability of slag refractories due to the protective effect of slopes and bottom filling and the reduction or complete suppression of dust emission when loading the flux mixture allows reducing the refractory consumption.

Simplification of the slag removal technology from the slag by creating conditions for the complete dissolution of the refractory melting dust in the slag and obtaining liquid slag without burning additional fuel in the slag, while ensuring the increased durability of the slag, solves the problem of liquid slag removal from the slag of the hearth furnaces.

The slag produced by the proposed method mainly consists of oxides of iron and calcium and can be used in metallurgy.

Claims (2)

1. A method of removing slag from a slag of a steel-smelting hearth furnace in a liquid state, including trapping melting dust in a slag, periodically feeding the flux mixture to a slag, and periodically releasing slag from a slag, characterized in that in order to increase the durability of the slag and increase productivity furnace, the composition of flux the mixture is injected limestone, iron ore and combustible material, the flux mixture is loaded in a concentrated manner on the hearth and slag ditch in an amount of 1.5-5.0 kg per kg of collected dust, while the combustible material is fed in an amount of 0.5-5 % of the total amount of the fluxing mixture, and the level of slag in the slag is changed stepwise by partial release of slag. 0 2. A device for removing slag from the slag of a steel-smelting hearth furnace in the liquid state, comprising a vertical channel, a slag including a front, a pass and side walls, a bottom with slopes, a tap located in the front 5 a slag wall at the bottom and a boot window located in the wall of the slag, characterized in that, in order to increase the durability of the slag and increase the productivity of the furnace, it is equipped with additional working tap holes located in the end wall of the slag wall at different levels vertically, and the working notch is 1 / 10-1 / 15 slope height from the bottom, while the bottom and the slopes are made of small-sized limestone and 5 iron oxides, the hearth is horizontal, and the loading window is located in the side wall of the slag along the axis of the vertical channel.