KR20120075689A - Deoxidation method of pouring molten metal by electric arc furnace - Google Patents

Abstract

PURPOSE: A deoxidation method of pouring molten metal by an electric arc furnace is provided to prevent a thermal damage of the lower part of an electric arc furnace and a molten steel overflow in a teeming ladle by efficiently inserting a recarburizer and alloy steel. CONSTITUTION: A deoxidation method of pouring molten metal by an electric arc furnace comprises the next step. Lump coal(10) of 50 to 70kg is inserted into on the bottom of a teeming ladle(5) based teeming amount 92±2 ton before tapping molten steel in which an electronic furnace task is completed to the teeming ladle. After inserting the lump coal, the molten steel is tapped to the teeming ladle. A ferro alloy is inserted in the middle of or right after a tapping of the molten steel to the teeming ladle. The lump coal less than 30kg is additionally inserted into the teeming ladle after tapping the molten steel and inserting the alloy steel. In the state that a temperature of the tapped molten steel is 1570°C or greater, the lump coal is additionally inserted.

Description

Deoxidation method of molten steel for electric furnace {DEOXIDATION METHOD OF POURING MOLTEN METAL BY ELECTRIC ARC FURNACE}

The present invention relates to a deoxidation method of molten steel in the electric furnace, more specifically, in removing the dissolved oxygen present in the molten steel in the tapping of the molten steel completed by the electric furnace work, the quality of molten steel by maintaining a constant carbon component in the molten steel Method for deoxidation of electric furnace molten steel that can reduce the production cost of carbon steel products produced by reducing the input of ferroalloy in the LF (ladle furnace) refining process to improve the stability and stability of molten steel. will be.

In general, an electric furnace process is made of molten steel by first charging the scrap metal into an electric furnace and simultaneously using arc heat generated by supplying electric power to electrodes. Then, the molten steel is blown into the slag layer, which is an impurity component in the molten steel, for the purpose of forming carbon and oxygen sources (C + O ₂ ) by using a furnace nance and a burner burner so as to have a desired temperature and component composition. To oxidize the supplied carbon (C) source. Using the heat of oxidation reaction generated during the oxidation reaction, the molten steel is heated up to the target temperature (1600 ± 10 ° C), and the impurities in the molten steel are oxidized and refined, and the tapping is performed on the steel ladle for the next step, LF refining.

When tapping the molten steel after the electric furnace process is completed by tapping the steel ladle, a subsidiary material input chute, which is an auxiliary facility with an electric furnace of ferroalloy and carbonaceous material, is used to control the deoxidation of dissolved oxygen remaining in the molten steel and the composition of carbon steel immediately before or after the tapping. To the molten steel. At the same time, when ferrous alloys and charcoal agents are added at the same time, it may cause severe thermal damage to the lower part of the furnace due to the occurrence of flames and high heat due to rapid chemical reactions, and sometimes overflow of molten steel in the steel ladle due to the inflow of slag. This can lead to an accident in which the process can be stopped due to damage to the equipment.As the dissolved oxygen reacts with the expensive ferroalloy earlier than the low-cost carburizing agent, the recovery rate of ferroalloy is lowered, resulting in an increase in the manufacturing cost of the carbon steel product. There was a following problem.

In order to solve this problem, Patent No. 10-0917471 (Carbon supply method for deoxidation of molten steel into an electric furnace) has been developed. Patent No. 10-0917371 discloses by supplying fine alloyed coal, which is a charcoal agent, by using carbon injection, which is an air injection method, to molten steel in an electric furnace prior to the input of ferroalloy, and then supplying ferroalloy to a steel ladle that is pulled out. We tried to solve the problem.

By the way, the conventional Patent No. 10-0917471 can improve the thermal damage or molten steel overflow phenomenon in the lower part of the furnace, but in order to supply coal powder, carbon injection must be installed in the electric furnace separately, and the carbonaceous agent supplied due to the characteristics of the carbon injection Because of fine powdered coal, the loss rate is high due to frequent clogging and scattering of the inlet, and it is not possible to separately recover the oxide-type ferroalloy component present in the slag layer after the ferroalloy is added. Since the input amount of ferroalloy must be increased to manufacture carbon steel, there is a problem in that the manufacturing cost of the manufactured carbon steel product is high and the manufacturing efficiency is lowered.

Therefore, the technical problem to be solved by the present invention is to solve the above problems by removing the dissolved oxygen remaining in the molten steel during the tapping of the molten steel is completed in the furnace process and without adding additional equipment to adjust the composition of the carbon steel, without adding additional equipment By introducing iron efficiently, it prevents severe thermal damage in the lower part of the furnace and overflow of molten steel in the steel ladle, and increases the recovery of ferroalloy in the slag layer, thereby reducing the amount of ferroalloy in the LF refining process. An object of the present invention is to provide a deoxidation method of molten steel for electric tapping which can lower the manufacturing cost of carbon steel products to be manufactured.

The deoxidation method of the electric furnace tapping molten steel according to the present invention for solving the above problems is 50 to 70 kg based on the amount of 92 ± 2 ton on the bottom of the tapping ladle before tapping the molten steel after the electric furnace work is completed to the tapping ladle The step of injecting the coal briquettes, the step of tapping the molten steel to the steel ladle after the completion of the input of the coal briquettes, and the step of injecting ferroalloy into the steel ladle during or immediately after the tapping of the molten steel.

After completion of the molten steel tapping and the addition of the ferroalloy may further comprise the step of additionally adding less than 30 kg of lump coal to the steel ladle.

In the additional charging step of the coal briquettes, it is preferable that the molten steel is thrown in a state where the temperature of the molten steel is 1570 ° C. or more.

The lump coal has a fixed carbon of 76.8% or more, and the particle size is preferably 30 to 50 mm.

The injection or addition of the coal coal is carried out through a coal coal feeder installed in the vicinity of the electric furnace, and the installation angle of the coal feeder of the coal feeder is 40 to 50 ° horizontally, and the end of the coal feeder chute and the tap The distance between the tops of the fields is preferably 0.8 to 1.2 m.

As described above, according to the deoxidation method of the molten steel tapping furnace according to the present invention, inexpensive charcoal agent without additional equipment to remove dissolved oxygen remaining in the molten steel and adjust the composition of carbon steel when the molten steel is completed. And a small amount of ferroalloy can be injected efficiently to prevent severe thermal damage to the lower part of the furnace and overflow of molten steel in the steel ladle, and to improve the recovery of ferroalloy in the slag layer in the LF refining process There is an advantageous effect that can reduce the manufacturing cost of the carbon steel product produced by reducing the input amount of ferroalloy.

1 to 4 are each a front view sequentially showing a deoxidation method of the molten steel tapping furnace according to an embodiment of the present invention,
1 is a front view showing a process of firstly injecting coal briquettes into the steel ladle before the molten steel furnace;
2 is a front view showing a process of waiting for tapping by moving to a lower part of the tapping ladle in which primary coal briquettes are completed;
3 is a front view showing a step of tapping the molten steel in the tapping ladle moved to the lower part of the electric furnace, and
4 is a front view illustrating a process of moving the tapping ladle after the molten steel tapping into the first lump coal injecting position and then injecting the lump coal in the second order.

Specific details of other embodiments are included in the detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent by reference to the embodiments described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various other forms, and it should be understood that the present embodiment is intended to be illustrative only and is not intended to be exhaustive or to limit the invention to the precise form disclosed, To fully disclose the scope of the invention to a person skilled in the art, and the invention is only defined by the scope of the claims.

Like reference numerals refer to like elements throughout. Embodiments described herein will be described with reference to the ideal front view of the present invention.

Hereinafter, the general operation of the electric furnace 1 and the tapping operation of the tapping ladle 5 of the molten steel of the electric furnace 1 are the same as in the prior art, so the description thereof is omitted, and with reference to the accompanying drawings of the present invention A detailed description will be given with reference to FIGS. 1 to 4 based on a deoxidation method of an electric furnace tapping steel according to one embodiment.

1 is a front view showing a process of first injecting the coal briquettes into the steel ladle before the electric furnace molten steel tap, Figure 2 is a front view showing a process of waiting for the tapping by moving the tapping ladle completed the first injection of the coal briquettes to the bottom of the electric furnace. 3 is a front view showing the process of tapping molten steel on the steel ladle moved to the lower part of the electric furnace, and FIG. 4 is a process of injecting the coal briquettes after the molten steel is moved to the first lump coal injecting position. It is a front view showing.

In the deoxidation method of the electric furnace tapping steel according to an embodiment of the present invention, first, before tapping the molten steel 20 (see FIG. 3) having completed the operation of the electric furnace 1 as shown in FIG. 1 to the tapping ladle 5. 50 to 70 kg of lump coal 10 is first introduced to the bottom of the water ladle 5 based on the amount of water 92 ± 2 ton.

The lump coal 10 is a carbonaceous agent or deoxidizer used to promote deoxidation of molten steel, and has a fixed carbon of 76.8% or more and agglomerate type compared to powdered coal, and thus has a small particle size of 30 to 50 mm. , During the preparation of the tapping time of the molten steel, directly into the bottom of the receiving ladle (5) using the coal briquette injector (2).

The lump coal feeder 2 used in this embodiment for the lump coal 10 feeding is a ladle carbon feeder, which is installed near the exit of the electric furnace 1. The installation angle of the pipe chute 2a of the lump coal feeder 2 is preferably 40 to 50 ° horizontally, more preferably 44 °. On the other hand, the distance between the tip of the closing chute 2a and the upper part of the receiving ladle 5 is preferably 0.8 to 1.2 m, more preferably 1 m. If the installation angle of the feed chute 2a is less than 40 ° or the distance between the upper portion of the water receiving ladle 5 and the tip of the feed chute 2a is shorter than 0.8m, the feed rate of the coal briquettes 10 is lowered to increase the feed time and work efficiency. There is a problem that this is lowered, on the contrary, if the installation angle exceeds 50 ° or the distance between the upper part of the receiving ladle 5 and the end of the feeding chute 2a is longer than 1.2m, the feeding speed of the coal briquettes 10 is excessively increased, thereby introducing the coal briquettes. This is because when the slag layer is scattered or injected directly into the molten steel, the reaction with the slag layer does not occur, and thus the purpose of recovering the ferroalloy of the slag layer cannot be achieved.

On the other hand, the input time of the coal briquette 10 is when the loading ladle 5 enters the EBT eccentric bottom tapping position when the receiving ladle 5 enters the tapping cart, and the input chute 2a of the coal briquette injector 2 and the receiving ladle 5 coincide with each other. It is preferable to inject | pour in time.

In addition, the input amount of the lump coal 10 is preferably 50 to 70 kg based on the amount of tapping out of the molten steel 20 of the electric furnace 1, that is, the tapping amount of 92 t ± 2 ton of the tapping ladle 5. Since the carbon content of the molten steel in the electric furnace is 0.14 ± 0.03%, the carbon increase is approximately 0.042% when 50 kg of coal is injected, and the carbon increase is about 0.058% when 70 kg is injected, so that the carbon composition of the molten steel is required before arriving at the secondary refining process. This is because the composition can be 0.18 to 0.20%.

However, it is a matter of course that the numerical value of the input amount of the coal briquettes can be appropriately added or subtracted according to the present conditions of the electric furnace 1 operation and the composition of the target steel grade.

When the first injection of the coal briquettes is completed, as shown in FIG. 2, the ladle ladle 5 moves to the lower portion of the electric furnace 1 in the direction of the arrow for the tapping of the molten steel and waits for the tapping of the molten steel.

When the waiting for the tapping is completed, the molten steel 20 is tapped into the tapping ladle 5 through the tapping hole by tilting the electric furnace 1 as shown in FIG. 3.

In addition, although not shown in the drawing, alloy iron is added together to the steel ladle 5 during or immediately after the tapping of the molten steel 20. In this embodiment, the ferroalloy is made of silicic manganese (Si-Mn) and silicon iron (Fe-Si), and the dosage is about 400 to 450 kg of silicon and 100 to 140 kg of silicon.

Thus, the problem of occurring when simultaneously supplying the carbonaceous agent and the ferroalloy can be solved by completely separating the gaseous coal and ferroalloy and supplying the molten steel with time difference. In addition, the use of coal briquettes as a catalyst for decay and the maintenance cost of the coal dust, which is a problem in using coal powder, makes it difficult to check the presence or absence of additional equipment in the electric furnace (1). There is an advantageous effect that can be carried out easily and precisely.

Upon completion of the molten steel tapping and ferroalloy, as shown in FIG. 4, the steel ladle 5 is moved back to the arrow direction by the bogie and moved to the LF refining process equipment for the next process. At this time, when the steel ladle 5 is positioned at the point shown in FIG. 1 to recover and recover the expensive ferroalloy oxide contained in the slag layer in molten steel, the slag layer of the slag layer 5 may be 30 kg or less. The coal briquette 10 is further added using the coal briquette injector 2.

At this time, if the input amount of the ingot coal 10 added is excessive, since the molten steel overflow phenomenon may occur due to the rapid chemical reaction of carbon and oxygen, the input amount is set so as not to exceed 30 kg.

On the other hand, the additional injection of the coal briquettes should be carried out in a state that the temperature of the molten steel 20 is 1570 ℃ or more. The reason for this is that when the temperature of the molten steel 20 falls below 1570 ° C., the slag layer is solidified even if the coal is further added, thereby reducing the re-reduction reaction of ferroalloy oxide, thereby rapidly reducing the recovery of ferroalloy.

Therefore, the temperature of the molten steel is 1600 ± 10 ℃ when tapping the molten steel, taking into consideration that it takes about 60 seconds for the molten steel to fall below 1570 ℃ at room temperature. The moving time of 5) should be determined so that the moving ladle 5 is faster than the above time considering the additional injection time of the coal briquettes.

After the molten steel tapping and the addition of ferroalloy is added again, the addition of lump coal can not only solve the problems of the prior art due to the simultaneous addition of ferroalloy and the carbonaceous agent, but also advantageous to re-recover the alloy iron contained in the slag layer into molten steel. It works.

As described above, according to the deoxidation method of the molten steel tapping furnace according to the present invention, after the coal briquette 10 is first introduced into the bottom of the steel ladle 5 before the molten steel tapping, the oxygen of the molten steel and the carbon of the coal briquettes are first reacted through tapping. This is made primarily, followed by the introduction of ferroalloy for carbon steel composition adjustment to the steel ladle (5) that is outgoing to solve the problems of the prior art according to the simultaneous injection of the cast iron and ferroalloy, and again oxidized ferroalloy By recovering through the second lump coal injection, there is an advantageous effect that can reduce the production cost of the carbon steel by reducing the input amount of the ferroalloy and the carbonaceous agent in the LF refining process.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, And falls within the scope of the invention.

1: electric furnace 2: lump coal injector
2a: chute 5: ladle
10: Goetan 20: molten steel

Claims (5)

Injecting 50 to 70 kg of lump coal on the basis of the amount of 92 ± 2 tons of water into the bottom of the water ladle before the molten steel is finished to the water ladle.
Tapping the molten steel on the tapping ladle after the ingot coal loading is completed;
Injecting ferroalloy into the steel ladle during or immediately after tapping of the molten steel
Containing
Deoxidation method of molten steel for electric furnace. In claim 1,
After the molten steel tapping and the addition of the ferro-alloy is completed, further comprising the step of adding a less than 30 kg of lump coal to the steel ladle
Deoxidation method of molten steel for electric furnace. In claim 2,
The additional input step of the coal coal
In the state that the temperature of the molten steel is out 1570 ℃ or more
Deoxidation method of molten steel for electric furnace. In claim 1,
The lump coal has a fixed carbon of at least 76.8%, the particle size is 30 to 50 mm
Deoxidation method of molten steel for electric furnace. The method of claim 1 or 2,
The injection or addition of the lump coal is carried out through the lump coal injector installed in the vicinity of the electric furnace,
The installation angle of the feed chute of the lump coal feeder is 40 to 50 ° horizontally, and the distance between the end of the lump coal feed chute and the top of the receiving ladle is 0.8 to 1.2 m.
Deoxidation method of molten steel for electric furnace.

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