KR102115886B1 - Method for refining molten steel and refining equipment using converter - Google Patents

Abstract

In the converter refining method according to the present invention, oxygen is blown into the converter, the molten iron in the converter is blown, the process of manufacturing molten steel, the end point nitrogen concentration (N _e ) during the blowing is predicted, and carbon is contained in the converter according to the predicted results depending on whether or not the determining of input if the raw material, after blowing, satisfies the end point the molten steel temperature (T _em) process, a reference tapping temperature (T _et) the measured end point molten steel temperature (T _em) for measuring, by a converter And determining whether to input the carbon-containing raw material, depending on whether or not to input the carbon-containing raw material, determining whether to enter ferro silicon into the converter before the steel is discharged, and to discharge the molten steel from the converter.
Therefore, according to the embodiment of the present invention, even if the volume of the slag is expanded by injecting the carbon-containing raw material during the refining of the converter, it is possible to effectively reduce the slag volume by introducing ferro silicon (FeSi) before exiting. Therefore, as in the prior art, after the slag is pre-excluded with the slag port before the steel is discharged, the molten steel can be immediately discharged without going into the molten steel.

Description

 Method for refining molten steel and refining equipment using converter}

The present invention relates to a converter refining method and a converter refining device, and more particularly, to a converter refining method and a converter refining device that facilitates exit and exit.

The general steelmaking process includes a refining process in which oxygen and oxides are removed from molten steel by a refining operation that blows oxygen during refining.

The oxygen blown into the converter reacts with carbon (C) in the molten steel, whereby carbon in the molten steel is removed in the form of carbon monoxide (CO), and nitrogen is removed by the carbon monoxide.

However, as the oxygen concentration in the molten steel increases, the carbon concentration in the molten steel is, for example, up to a level of 0.05%, but nitrogen is present at 20 ppm or less, but as the carbon concentration in the molten steel decreases at the end of the blow, there is insufficient carbon to react with oxygen. Is mainly reacted with iron (Fe) in molten steel.

In addition, exhaust gas such as CO is generated by the reaction between oxygen and carbon. At the end of the blow, carbon in the molten steel is insufficient, and thus the amount of exhaust gas is reduced. As a result, negative pressure is generated inside the converter. Through the furnace. In this way, the nitrogen concentration in the molten steel rises to 30 ppm to 40 ppm by the air flowing into the converter, and the oxygen concentration also increases.

Nitrogen in molten steel forms precipitates such as AlN, VCN, and NbCN inside the slab during continuous casting, and during rolling, the precipitates increase the local brittleness inside the slab.

In order to solve the problem of high nitrogen concentration in molten steel, carbon-containing raw materials were conventionally introduced during refining. By the way, when the carbon-containing raw material is input, the converter slag and the carbon-containing raw material continuously react, and the slag overflows into the furnace during the course of the steelmaking. Due to this, it becomes difficult to tilt the converter for attendance. Accordingly, a slag port is disposed on the outside of the converter, and a certain amount of slag is tilted to the charging side to be discharged, and then a lifting operation is performed.

However, when using the slag port as described above, the following problems occur. First, as the temperature of the molten steel decreases by 20 ° C to 30 ° C when it is excluded through the slag port slag, the worker considers this, and the temperature of the molten steel is 20 ° C to 30 ° C higher than the temperature at the time of inputting the carbon-containing raw material Control, but there is a problem that oxygen must be supplied for this. Second, as the molten steel is discharged after slag exclusion, the residence time of the molten steel in the converter becomes longer, and there is a problem that the erosion of the furnace body is increased due to the reaction between oxygen in the molten steel and the lead of the converter. Third, since the slag exclusion work takes 3 to 4 minutes, there is a problem in that the casting time is delayed or the continuous casting (casting) connection time is insufficient, so that the casting cannot be performed and the short circuit cannot be performed.

Korea Patent Publication 10-2012-0023401

The present invention provides a converter refining method and a converter refining device capable of shortening the residence time of molten steel in a converter.

The present invention provides a converter refining method and a converter refining device that do not require slag exclusion before exiting.

The converter refining method according to an embodiment of the present invention includes a process of preparing oxygen by blowing oxygen into the converter and then blowing the molten iron in the converter; Predicting the end point nitrogen concentration (N _e ) during the blow and determining whether to input the carbon-containing raw material into the converter according to the predicted result; Measuring the end point temperature (T _em ) of the molten steel after the blowing; Determining whether to input the carbon-containing raw material into the converter according to whether the measured end temperature (T _em ) of the molten steel satisfies a reference exit temperature (T _et ); Determining whether ferro silicon is injected into the converter before the steel is discharged according to whether the carbon-containing raw material is injected; It includes; the process of elevating the molten steel from the converter.

The process of predicting the end point nitrogen concentration (N _e ) during the blow includes measuring the temperature and carbon concentration of the molten iron during the blow; And predicting the end point nitrogen concentration (N _e ) using the measured temperature, carbon concentration, end point target carbon concentration (C _et ), and the reference exit temperature (T _et ).

The process of determining whether to input the carbon-containing raw material into the converter according to the prediction result includes: determining whether the predicted end point nitrogen concentration (N _e ) is less than a reference nitrogen concentration (N _t ); And when the predicted end point nitrogen concentration (N _e ) is greater than or equal to the reference nitrogen concentration (N _t ), introducing a carbon-containing raw material into the converter.

After the start of the blow, when the time at which the blow ends is 100%, the time at which the blow is started is 70 to 80% from the start of the blow is called a dynamic time, and the temperature and carbon concentration of the molten iron during the blow are measured. In the above, the temperature and the carbon concentration of the molten iron measured during the blow are measured at the dynamic time point, respectively, are referred to as dynamic temperature (T _D ) and dynamic carbon concentration (C _D ), and the predicted end point nitrogen concentration (N _e ). The process of determining whether or not is less than the reference nitrogen concentration (N _t ), by using the dynamic temperature (T _D ), in order to achieve the reference exit temperature (T _et ), from the dynamic time point to the end of the blow Calculating a first required oxygen amount (0 ₁ ) that is an oxygen amount; Calculating a second required oxygen amount (O ₂ ), which is the amount of oxygen required from the dynamic time point to the end of the blow, to achieve the end target carbon concentration (C _et ) using the dynamic carbon concentration (C _D ); Any one of the first required amount of oxygen (O ₁ ) and the second required amount of oxygen (O ₂ ) is added to the amount of oxygen blown from the start of the blow to the dynamic time, and the amount of oxygen ( _D ) is blown from the start of blow A process of calculating the end oxygen amount (O _e ), which is the amount of oxygen to be blown up to the end point; a process of setting a reference oxygen amount (O _t ) by adding the second required oxygen amount (O ₂ ) and 400 Nm ³ ; It is determined whether the value obtained by subtracting the dynamic oxygen amount O _D from the end oxygen amount O _e is equal to or less than the reference oxygen amount O _t , and the predicted end point nitrogen concentration N _e is the reference nitrogen concentration ( N _t ).

In determining whether the end point nitrogen concentration N _e is less than the reference nitrogen concentration N _t , a value obtained by subtracting the end point oxygen amount O _e from the dynamic oxygen amount O _D is the reference oxygen amount O _{When t} ) or less, it is determined that the end point nitrogen concentration (N _e ) is less than the reference nitrogen concentration (N _t ), and the value obtained by subtracting the amount of dynamic oxygen (O _D ) from the end point oxygen amount (O _e ) is the reference oxygen amount ( When it exceeds O _t ), it is determined that the end point nitrogen concentration (N _e ) is equal to or greater than the reference nitrogen concentration (N _t ).

Whether the value obtained by subtracting the dynamic oxygen amount O _D from the end oxygen amount O _e is equal to or less than the reference oxygen amount O _t , and subtracting the dynamic oxygen amount O _D from the end oxygen amount O _e The end point nitrogen concentration (N _e ) is predicted according to a deviation between a value and the reference oxygen amount (O _t ).

The input amount of the carbon-containing raw material is determined according to a deviation between the end point oxygen amount O _e and the value of the dynamic oxygen amount O _D and the reference oxygen amount O _t .

According to whether the measured end temperature (T _em ) of the molten steel satisfies the reference exit temperature (T _et ), in determining whether to input the carbon-containing raw material into the converter, the measured end temperature (T _em) of the molten steel ) Is less than the reference exit temperature (T _et ), the carbon-containing raw material is introduced into the converter.

In the introduction of the ferro silicon, the ferro silicon is introduced at 0.03% to 0.07% of the molten iron amount in the converter.

A converter having an interior space; A main lance capable of blowing oxygen into the converter so as to blow the molten iron in the converter; During the blow, a prediction unit for predicting the end point nitrogen concentration (N _e ); A precipitation determination unit that compares the measured end temperature of the molten steel (T _em ) with the reference exit temperature (T _et ) and determines whether the molten steel is available or not; And an input control unit that determines whether ferro silicon is injected into the converter according to the predicted end point nitrogen concentration (N _e ) predicted by the prediction unit and whether or not precipitation is possible in the precipitation determination unit.

A first hopper in which carbon-containing raw materials to be introduced into the converter are stored, according to the predicted end point nitrogen concentration (N _e ) predicted by the predicting unit and a result of determining whether or not it is possible to exit the determining unit; And a second hopper in which the ferro silicon is stored, wherein the input control unit is configured to determine the end point nitrogen concentration (N _e ) predicted by the predicting unit and whether or not it is possible to exit from the precipitation determining unit, before the precipitation of the molten steel. The operation of the second hopper is controlled so that ferro silicon is introduced into the converter.

In the input control unit, when the end point nitrogen concentration N _e predicted by the prediction unit is determined to be equal to or higher than the reference nitrogen concentration N _t , and the end point temperature T _em of the molten steel is determined by the exit determination unit, the reference exit temperature T _et ), the operation of the second hopper is controlled such that ferro silicon is introduced into the converter before at least one of the cases determined to be less than that.

In the input control unit, when the end point nitrogen concentration N _e predicted by the prediction unit is determined to be equal to or higher than the reference nitrogen concentration N _t , and the end point temperature T _em of the molten steel is determined by the exit determination unit, the reference exit temperature T _et ), the operation of the first hopper is controlled so that the carbon-containing raw material is introduced into the converter.

In the prediction unit, in predicting the end point nitrogen concentration (N _e ), the temperature, carbon concentration, end point target carbon concentration (C _et ), and the reference exit temperature (T _et ) measured during the blow are used. Then, the end point nitrogen concentration (N _e ) is predicted.

The input control unit controls the operation of the second hopper to inject the ferro silicon into the converter in an amount of 0.03% to 0.07% of the molten iron dose.

According to the embodiment of the present invention, even if the volume of the slag is expanded by injecting the carbon-containing raw material during the refining of the converter, it is possible to effectively reduce the slag volume by introducing ferro silicon (FeSi) before exiting. Therefore, as in the prior art, after the slag is pre-excluded with the slag port before the steel is discharged, the molten steel can be immediately discharged without going into the molten steel.

Therefore, when the slag pot is used as in the prior art, there is no problem that the temperature of the molten steel decreases, so it is not necessary to adjust the temperature of the molten steel to a temperature of 20 ° C. to 30 ° C. higher than the standard exit temperature when the carbon raw material is introduced. In addition, since the slag pre-working material is omitted, there is no problem that the continuous casting time is delayed.

In addition, since no slag pre-coating using a slag port is performed, the time for the molten steel to stay in the converter can be shortened. Therefore, erosion in the converter can be reduced as compared to the prior art.

1 is a schematic view showing a converter refining apparatus according to an embodiment of the present invention
Figure 2 is a flow chart showing a converter refining method according to an embodiment of the present invention

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and the scope of the invention to those skilled in the art. It is provided to inform you completely.

1 is a schematic view showing a converter refining apparatus according to an embodiment of the present invention. 2 is a flow chart showing a converter refining method according to an embodiment of the present invention.

Referring to FIG. 1, the converter refining apparatus according to the embodiment of the present invention includes a converter 100 in which an internal space in which refining is performed is provided, and a main lance 200 positioned above the converter 100 to intake oxygen. , The driving unit 700 for raising and lowering the main lance 200, and a prediction unit 410 for predicting the nitrogen concentration at the end of the blow or at the end of the blow, according to the measured temperature and carbon concentration (or carbon content) of the molten iron. Wow, the first hopper 600a for receiving and weighing the carbon-containing raw material to be input to the converter 100 according to the prediction result from the prediction unit 410, the end point molten steel temperature (T _em ) and the reference exit temperature (T _et ), And a second determining unit for receiving and weighing ferro silicon (FeSi) to be fed into a converter before the departure, if it is determined that the attendance determination unit 420 determines whether or not it is possible to exit and if the exit determination unit 420 determines that it is possible to exit. The hopper 600b, the prediction unit 410, the departure determination unit 420, and the first and second hoppers 600a and 600b are signally connected to the prediction unit 410 and the departure determination unit 420 It includes an input control unit 430 for controlling the operation of the first and second hoppers (600a, 600b) according to the prediction and determination results in.

In addition, the converter refining apparatus according to an embodiment of the present invention is charged into the oxygen supply unit 500, the converter 100 storing the oxygen to be supplied to the main lance 200, the raw material, that is, melt sampled, the temperature thereof, Probe 310 for measuring the component content, etc., the sub lance 300 provided at the tip, the oxygen supply line 500 connecting the oxygen supply unit 500 and the main lance 200, 510, oxygen supply line 510 It is installed on the extended path of the main lance 200 includes a valve (V) for controlling the flow of oxygen and the supply flow rate.

The converter 100 is a container having an internal space, and the upper side is open (nozzle 120, and a discharge port 130 through which molten steel is discharged is provided on the side. The converter 100 is made of iron and refractory materials. More specifically, the converter 100 constitutes the outermost wall or the outer wall, and is constructed on an inner wall surface of an iron shell and an iron shell made of a metal material, and includes a lead wire made of a refractory material. Permanently-constructed confectionery built on and may include a refractory condensed on the inner wall surface of the permanently refurbished.

In addition, a lower odor nozzle 110 in which an inert gas for stirring the molten steel is blown is provided at a lower portion of the converter 100. The deodorizing nozzle 110 provided at the lower portion of the converter 100 blows an inert gas, such as Ar gas, into the converter 100, thereby improving agitation and reactivity of the raw materials introduced into the converter 100 during blowing.

The main lance 200 is a means for injecting oxygen into the converter 100, and can be moved up and down by the driving unit 700, and may be installed through the furnace port 120 of the converter 100. The main lance 200 includes a body having an inner space formed extending in the vertical direction and a nozzle which is a hole provided at the bottom of the body so that the inner space communicates with the outside of the body. According to the main lance 200, oxygen moved along the inner space of the body is blown out through the nozzle.

The sub lance 300 may include a main body extending in the vertical direction and a probe 310 connected to the bottom of the main body. The sub lance 300 may be moved up and down by the driving unit 700.

Each of the first hopper 600a and the second hopper 600b may include a storage portion in which raw materials to be loaded into the converter 100 are stored, and a chute extending from the storage unit toward the furnace port 120 of the converter.

The predicting unit 410 predicts the nitrogen concentration in the molten steel at the blowing end point. A method of predicting the end point nitrogen concentration (N _e ) by the prediction unit 410 will be described in detail later.

The precipitation determination unit 420 compares the end point molten steel temperature (T _em ) with the reference exit temperature (T _et ), and determines whether or not the molten steel in the converter 100 has been blown or refined, that is, whether molten steel can be started.

The converter 100 is a facility for refining molten iron to produce molten steel, and the molten iron that has been blown out is usually referred to as molten steel. Accordingly, the end point molten steel temperature T _em may be referred to as the end point molten iron temperature T _em .

In addition, after the blowing is completed, the temperature of the molten iron or molten steel (that is, the end point temperature) should be the target reference temperature, and the molten steel can be discharged from the converter.

Here, the reference tapping temperature (T _et) is a temperature serving as a reference of the molten iron that is, molten steel tapping the blowing is finished, based on tapping temperature (T _et) may be designated as the end point target temperature of the molten steel or molten iron (T _et) .

The input control unit 430 operates the first hopper 600a when the end point nitrogen concentration N _e predicted by the prediction unit 410 is not less than the reference nitrogen concentration N _t (that is, abnormal). Carbon-containing raw materials are introduced into the converter 100. In addition, when it is determined that the exit control unit 430 is capable of exiting, the input control unit 430 operates the second hopper 600b before exiting to input ferro silicon (FeSi) into the converter 100.

Hereinafter, a converter refining method using a converter refining apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

Referring to Figure 2, the converter refining method using a converter refining apparatus according to an embodiment of the present invention is a process for preparing the converter refining of the molten iron by charging scrap metal and molten iron into the converter 100 (S100), main lance ( 200) the process of initiating a blow by injecting oxygen into the molten iron charged in the converter 100 (S200), the temperature of the molten iron at a point where it is 70 to 80% (aka dynamic) from the time when the first blow is started. And the process of measuring the carbon concentration in the molten iron (S300), using the measured temperature and carbon concentration of the molten iron, to predict the nitrogen concentration at the blown end point, the predicted end point nitrogen concentration (N _e ) is the reference nitrogen concentration (N _t ) determining whether it is less than (S400), when the predicted end point nitrogen concentration (N _e ) is greater than or equal to the reference nitrogen concentration (N _t ), the step of introducing a carbon-containing raw material (S410), the predicted end point nitrogen concentration (N) _e ) is less than the reference nitrogen concentration (N _t ), or the process of terminating the blow-in after the carbon-containing raw material is input (S500), after the blow-out is completed, the end point molten steel temperature (T _em ) and the end point oxygen concentration (O _em ) are measured. Process (S600), the process of determining whether the measured end point molten steel temperature (T _em ) satisfies the reference exit temperature (T _et ) (S710), the measured end point molten steel temperature (T _em ) is the reference exit temperature (T _et ) If satisfactory, the process of determining whether the carbon-containing raw material is injected into the converter during blow (S730), if the carbon-containing raw material is injected into the converter during blow, after introducing ferro silicon (FeSi) into the converter 100 (S810) , is less than that tapping the refined molten iron that is, the molten steel process (S820), the measured end point molten steel temperature (T _em) is based on tapping temperature (T _et), carbon in a converter to be raised to a standard tapping the molten steel temperature (T _et) Heating process (S720) including the process of introducing the containing raw material (S721), the process of determining whether the carbon-containing raw material is injected during tempering or for raising the temperature (S730), if the carbon-containing raw material is added to the converter, before going to class After introducing ferro silicon (FeSi) into the converter 100 (S810), a process of stepping the molten steel (S820) is included.

Here, the process of ending the blow (S500) means that once the predicted nitrogen concentration (N _e ) becomes less than the reference nitrogen concentration (N _t ), regardless of the subsequent re-blowing, the blow is terminated once. do.

The converter refining preparation process (S100) is a process of ending the charging of the former charge (S110), a primary exclusion process (S120) to partially exclude the remaining slag in the converter 100 (S120), and coating the inner wall of the converter 100 Process (S130), secondary exclusion process to exclude residual slag after primary excavation (S140), process of performing passionate acid in converter 100 (S150), and after loading scrap metal into converter 100 ( S160), the process of charging the molten iron (S170).

When scrap metal and molten iron are charged (160, 170) into the converter, the scrap metal is melted into a hot molten iron. In addition, scrapping melts scrap metal by the reaction heat.

Hereinafter, the raw material accommodated in the converter after scrap and molten iron are charged into the converter is referred to as a 'melting chart'. In addition, the amount of raw material contained in the converter after the loading of scrap metal and molten iron into the converter is the amount of molten iron in the converter.

Here, the process of coating the inner wall of the converter 100 (S130) will be described in more detail. First, after the primary slag exclusion is completed, the converter 100 is established, and then a coating agent is introduced, and nitrogen spray coating is performed. At this time, a raw material containing MgO may be used as a coating agent. When the nitrogen injection coating is finished, the converter 100 is tilted to the charging side, that is, the exit side, so that the slag remaining after the primary exhaust is coated on the inner wall of the converter 100. Thereafter, the slag remaining after coating the converter 100 is excluded (secondary exclusion).

In the process of performing the enthusiasm (S150), in order to set the target molten iron end temperature, that is, the end temperature of the molten steel (T _em ), or the end temperature of the molten steel (T _em ) or the reference exit temperature (T _et ), the molten steel When the heavy element reacts with oxygen, heat of reaction, heat required to melt scrap metal, and heat required to melt auxiliary materials input during converter refining, etc. are calculated to calculate heat input, sensible heat, heat storage, etc., and perform passion acid.

Subsequently, scrap metal and molten iron are charged in the converter 100 (S160, 170), the main lance 200 is lowered using the driving unit 700, and the molten iron accommodated in the converter 100 through the main lance 200. Oxygen (O ₂ ) is blown in from the upper side to start blowing (S20). When oxygen is blown in, it reacts with carbon (C) in the molten iron to become carbon monoxide (CO), and decarburization reaction in which carbon (C) in the molten iron is removed proceeds. At this time, nitrogen (N) is also generated by bubbles of carbon monoxide (CO). Is removed.

Next, during the converter refining, the temperature and carbon concentration of the molten iron are measured (S300), and it is measured at the time when the decarburization reaction is slowed. More specifically, when 100% of the time from the start of blow-start (or the first blow-start) to the end of blow-start for refining the converter is 100%, the decarburization reaction is slowed from 70% to 80% from the start of blow-start. This is due to the low concentration of carbon in the molten iron at this time. Accordingly, the temperature of the molten iron and the concentration of carbon in the molten steel are measured at a time of 70% to 80% after the start of blowing oxygen into the molten iron, which is called dynamic. The method of measuring the temperature and carbon concentration of the molten iron is a general method in the operation of the converter, and the probe 310 is mounted on the sub lance 300, and a method for measuring it is used.

How to measure the temperature and carbon of the molten iron during refining of the furnace to adjust the temperature and carbon of the current molten iron in order to have the target temperature (or reference exit temperature (T _et )) and dissolved oxygen concentration after refining the converter 100 To know if you should.

Hereinafter, for convenience of explanation, the temperature of the molten iron measured at the time of 70% to 80% from the start of the blow is the dynamic temperature (T _D ), the carbon concentration in the molten iron is the dynamic carbon concentration (C _D ), and the oxygen concentration in the molten iron is dynamic. The oxygen concentration, the amount of oxygen blown from the start time of the blow to the 70% to 80% time point is called a dynamic oxygen amount (O _D ).

The predicting unit 410 uses the reference exit temperature (T _et ), the dynamic temperature (T _D ), the end point target carbon concentration (C _et ), and the dynamic oxygen content (O _D ), and then the reference exit temperature (T _et ) after dynamics. Or the amount of oxygen required to achieve the end point target temperature (T _et ) (hereinafter referred to as the first required oxygen amount (O ₁ )), the amount of oxygen required to achieve the end point target carbon concentration (C _et ) after dynamics (hereinafter referred to as the second required) The amount of oxygen (O ₂ )) is calculated, and the amount of oxygen (O _e ) at the end point is calculated.

The first required oxygen amount (O ₁ ) is the theoretical amount of oxygen to be injected from the dynamics to the end point in order to meet the end point target temperature (reference exit temperature (T _et )) according to the dynamic temperature (T _D ), as described above. . The first required oxygen amount (O ₁ ) can be calculated by the following [Equation 1] using, for example, an end point target temperature (T _et ), a dynamic temperature (T _D ), and a temperature increase coefficient.

[Equation 1]

The heating temperature coefficient (Nm ³ / ℃) is the flow rate (Nm ³ ) required to raise the molten steel by 1 ° C, which is the amount of slag or residual slag in actual operation, the amount of raw materials such as quicklime and light dolomite, Si, Mn in molten steel , P may vary depending on the concentration of the component composition. And the temperature rise coefficient may be applied to a value within a predetermined numerical range by repeated operation, for example, may be 20 to 28Nm ³ / ℃.

Hereinafter, a method of calculating the first required oxygen amount O ₁ will be described as a specific example. For example, the end point target temperature (T _et) is 1640 ℃, and a dynamic temperature (T _D) 1540 ℃, the dynamic quantity of oxygen (O _D) the flow rate required for the temperature increase ^{10,000Nm 3, 1 ℃ (Nm 3} ) 25Nm 3, That is, suppose the temperature increase coefficient is 25 Nm ³ .

At this time, it can be seen that, by subtracting the dynamic temperature T _D from the end point target temperature (that is, the reference exit temperature T _et ), it is necessary to increase the temperature of 100 ° C. after the dynamic. And, because it is 1 ℃ the oxygen flow rate (Nm ³⁾ required for temperature increase 25Nm ^3, may have a 2500Nm ³ is required since the dynamic to the end point (Formula 1 used). Here, the calculated 2500 Nm ³ is the first required oxygen amount (O ₁ ).

The second required oxygen amount (O ₂ ) is the amount of oxygen to be injected from the dynamic point to the end point to meet the target carbon concentration (C _et ) according to the dynamic carbon concentration (C _D ), the total amount of molten steel, and the dynamic carbon concentration (C) _D ), the end point target carbon concentration (C _et ) can be calculated by Equation 2 below.

[Equation 2]

Hereinafter, a method of calculating the second required amount of oxygen (O ₂ ) will be described as a specific example. Normally, when removing 0.01 wt% of carbon, 38 Nm ³ is removed, and when the dynamic carbon is 0.4 wt%, the second required oxygen amount (O ₂ ) is 1520 Nm ³ by Equation 2. At this time, the blown oxygen may not remove 100% of the carbon in the molten steel, but when oxygen is blown over the calculated second required oxygen amount (O ₂ ), the end point carbon concentration becomes 0.02wt% to 0.04wt%.

The end point oxygen amount (O _e ) is calculated by summing the amount of oxygen injected up to the dynamic time point and the amount of oxygen to be injected from the dynamic time point to the end point. At this time, the amount of oxygen to be blown after the dynamic time point is an amount of oxygen having a larger value among the first required oxygen amount O ₁ and the second required oxygen amount O ₂ .

For example, when the dynamic oxygen amount O _D is 10,000 Nm ³ , the first required oxygen amount O ₁ is 2500 Nm ³ , and the first required oxygen amount O ₁ is 1520 Nm ³ , the dynamic oxygen amount O _D is 10,000 Nm ³ And 2500 Nm ³ , which is the first required oxygen amount (O ₁ ), is calculated to yield 12500 Nm ³ , which is the end point oxygen amount (O _e ).

When the first and second required oxygen amounts O ₁ and O ₂ and the end oxygen amount O _e are calculated in the prediction unit 410, the end nitrogen concentration N _e is predicted, and the predicted end nitrogen concentration N _e ) Is determined to be less than the reference nitrogen concentration (N _t ) (S400).

More specifically, in the prediction unit 410, the value obtained by subtracting the dynamic oxygen amount O _D from the end oxygen amount O _e is the amount of oxygen (hereinafter referred to as the reference oxygen amount) obtained by adding 400 Nm ³ to the second required oxygen amount O ₂ . (O _t )) It is predicted whether or not the predicted end point nitrogen concentration (N _e ) is less than the reference nitrogen concentration (N _t ), depending on whether or not.

For example, when the value obtained by subtracting the dynamic oxygen amount O _D from the end oxygen amount O _e is equal to or less than the reference oxygen amount O _t , it is determined that the predicted end point nitrogen concentration N _e is less than the reference nitrogen concentration N _t . Conversely, when the value obtained by subtracting the dynamic oxygen amount (O _D ) from the end oxygen amount (O _e ) exceeds the reference oxygen amount (O _t ), it is determined that the predicted end point nitrogen concentration (N _e ) is greater than or equal to the reference nitrogen concentration (N _t ). do.

On the other hand, the carbon concentration in the molten iron is low from the end of the blow, more specifically, after the dynamic point of view, and the decarburization reaction is slowed down. Therefore, since the oxygen blown at the end of the blowing has no carbon to react or has a small amount, it is mainly used to heat the molten iron by reacting with Fe in the molten iron. Therefore, at the end of the blowing, the amount of exhaust gas generated by the reaction between oxygen and carbon may or may not be generated.

Accordingly, the oxygen amount obtained by subtracting the dynamic oxygen amount O _D from the end oxygen amount O _e is, in other words, the amount of oxygen to be blown to the end point after the dynamic, so if the oxygen amount exceeds the second required oxygen amount O ₂ , the negative pressure This happens. This is because the amount of oxygen injected after dynamics is greater than the amount of oxygen required for decarburization (second required oxygen amount (O ₂ )), and oxygen injected after dynamics cannot be used for the decarburization reaction, or the amount of reaction is small, so that no exhaust gas is generated. Or it is because the generation amount is small.

Further, in the condition that (a quantity of oxygen subtracting the dynamic quantity of oxygen (O _D) at the end the amount of oxygen (O _e)) Dynamic quantity of oxygen to be blown from the end point after time exceeds the second required amount of oxygen (O _2), after the dynamic time When the amount of oxygen injected to the end point exceeds the amount of oxygen that is obtained by adding 400 Nm ³ to the second required amount of oxygen (O ₂ ), that is, the reference oxygen amount (O _t ), the actual nitrogen concentration in the molten iron (ie, the end point nitrogen concentration (N) _e )) becomes 30ppm or more.

On the other hand, nitrogen in molten steel forms precipitates such as AlN, VCN, and NbCN inside the slab during continuous casting, and the precipitates increase local brittleness inside the slab during rolling. However, when the nitrogen concentration in the molten steel is 30 ppm or more, the amount of precipitates such as AlN, VCN, and NbCN is large, and a defective slab is produced.

Therefore, in the example, the reference nitrogen concentration (N _t ) is 30 ppm.

In addition, the amount of oxygen which is blown after the dynamic time point to the end point the second required amount of oxygen (O ₂₎ of this, the amount of oxygen which is blown after the dynamic time point to the end point to exceed the second required amount of oxygen (O ₂₎ a sum of 400Nm ³ on the amount of oxygen In case of exceeding, since the end point nitrogen concentration (N _e ) becomes 30 ppm or more, the second required oxygen amount (O ₂ ) in determining whether the predicted end point nitrogen concentration (N _e ) is less than the reference nitrogen concentration (N _t ) ) Is determined based on the reference oxygen amount (O _t ), which is the sum of 400 Nm ³ .

Then, the amount of oxygen which is blown after the dynamic time point to the end point based on the amount of oxygen (O _t) for when it exceeds, according to the difference value of the dynamic quantity of oxygen to the reference amount of oxygen (O _t) is blown to the end point after point in time, to estimate the nitrogen concentration have. Then, the nitrogen concentration increases as the difference between the oxygen amount and the reference oxygen amount (O _t ) injected from the dynamic time point to the end point increases, and as the difference decreases, the nitrogen concentration decreases.

Therefore, the nitrogen concentration prediction according to the difference value can be performed by measuring the nitrogen concentration according to the difference value between the amount of oxygen and the reference oxygen amount (O _t ) injected from the dynamic time point to the end point through several experiments.

In addition, when the predicted nitrogen concentration is greater than or equal to the reference nitrogen concentration (N _t ), the endpoint oxygen concentration is greater than or equal to the reference oxygen concentration.

Accordingly, by determining whether the predicted end point nitrogen concentration N _e is less than the reference nitrogen concentration N _t , it is possible to determine whether the end point is overdose. That is, when the predicted end point nitrogen concentration (N _e ) is less than the reference nitrogen concentration (N _t ), it is predicted that the end point oxygen concentration will be less than the reference oxygen concentration and no odor will be generated. Conversely, when the predicted end point nitrogen concentration (N _e ) is greater than or equal to the reference nitrogen concentration (N _t ), it is predicted that the end point oxygen concentration will be greater than or equal to the reference oxygen concentration to generate odor.

If the prediction unit 410 predicts that the end point nitrogen concentration (N _e ) is greater than or equal to the reference nitrogen concentration (N _t ), the input control unit 430 is the first hopper 600a to adjust the inside of the converter 100 to positive pressure. By controlling the operation of the carbon-containing raw material to the converter (100). When the carbon-containing raw material is introduced into the converter 100, a flue gas is generated by a reaction between oxygen and carbon, and the converter 100 may be positive pressure depending on the amount of flue gas.

In order to generate flue gas so that the inside of the converter 100 becomes positive pressure, a carbon-containing raw material must be input. In the input control unit 430, the difference value between the oxygen amount and the reference oxygen amount O _t taken from the dynamic point to the end point, that is, The input amount of the carbon-containing raw material is determined according to the variation. Then, the first hopper controls the operation according to the input amount of the carbon-containing raw material determined by the input control unit 430 to input the carbon-containing raw material at the determined input amount.

On the other hand, oxygen in the converter 100 is reacted with a carbon-containing raw material to be removed by CO (carbon monoxide), etc. In theory, 93 kg of carbon per 100 Nm ³ of oxygen is required. However, in order to prevent the negative pressure from being generated inside the converter 100, the oxygen in the converter 100 reacts with the carbon-containing raw material and is removed with carbon monoxide or the like, and empirically, 180 kg of carbon per 100 Nm ³ of oxygen is required.

Here, the carbon-containing raw material may be, for example, a pellet embedded with carbon, and the carbon-containing raw material contains other components in addition to carbon. For example, when the carbon content of the carbon-containing raw material is 90 wt%, 200 kg of carbon-containing raw material per 100 Nm ^{3 of} oxygen is required.

For example, if the deviation between the reference oxygen amount (O _t ) from the amount of oxygen injected from the dynamic time point to the end point is 500 Nm ³ , the input control unit 430 calculates the input amount of the carbon-containing raw material as 1000 kg, and the first hopper 600a ) Controls the operation to input 1000kg of carbon-containing raw material. In this way, the input amount of the carbon-containing raw material is determined, and the inside of the converter can be positively pressured by inputting the determined amount, preventing or blocking outside air, that is, air being sucked into the converter.

On the other hand, when the carbon-containing raw material is introduced into the converter 100, oxygen and carbon react to generate CO, and 1 kg of carbon reacts with oxygen to generate 1.84 Nm ³ of gas, for example, CO gas. And, according to the law of thermodynamics, when the temperature in the converter is 1600 ℃, 2944Nm ³ of exhaust gas per 1kg of carbon-containing raw material is generated. Accordingly, when 1000 kg of carbon-containing raw material is introduced into the converter, 2,944,000 Nm ³ of exhaust gas is generated. Due to the generation of such flue gas, the converter becomes positive pressure, and outside air, that is, air is prevented or blocked from being sucked into the converter.

As the carbon-containing raw material is added as much as the above-mentioned input amount, the end point nitrogen concentration (N _e ) becomes less than the reference nitrogen concentration (N _t ). Thus, after the oxygen-containing raw material is introduced, the blowing is terminated (S500).

When the blow is finished, the temperature and oxygen concentration of the end point molten iron are measured using the sub lance 300 (S600).

Then, it is determined whether the measured end point molten steel temperature T _em satisfies the end point target temperature T _et , that is, the reference exit temperature T _et (S710). For example, when the measured end point molten steel temperature (T _em ) is less than the reference exit temperature (T _et ), the molten steel is heated (S720). In more detail, if it is determined that the measured end point molten steel temperature T _em is less than the reference exit temperature T _et , the input control unit 430 operates the first hopper 600a to carbon into the converter 100. The containing raw material is introduced (S721), and oxygen is again blown using the main lance 200, that is, re-strained (S722). At this time, the input amount of the carbon-containing raw material is determined according to the deviation between the end point molten steel temperature (T _em ) and the reference exit temperature (T _et ).

In this way, when the carbon-containing raw material is introduced into the converter 100, and re-straining is completed, the molten steel temperature becomes the reference temperature (T _et ), and thereafter comes out (S820).

On the other hand, if the predicted end point nitrogen concentration (N _e ) is higher than the reference nitrogen concentration (N _t ), or it is expected to overrun, the raw material containing carbon is converted into the converter, or the end point molten steel temperature (T _em ) is the reference exit temperature (T _et ). If less than, when the carbon-containing raw material is added, as described above, oxygen and carbon react to generate CO gas in the form of a bubble. The volume of the slag above the molten iron expands by the CO gas.

And, in order to exit to the exit 130 of the converter 100, the converter should be inclined at least 60 °. When the volume of the slag is expanded by CO gas, even if the converter is inclined by 30 ° to 40 °, 130) there is a problem that the slag comes out.

Therefore, in the embodiment of the present invention, whether or not ferro silicon is injected into the converter is determined according to whether the carbon-containing raw material is introduced into the converter (S730).

In other words, after the end of the blow, the end point molten steel temperature (T _em ) satisfies the reference exit temperature (T _et ) and is determined to be possible to exit, or the end point molten steel temperature (T _em ) is less than the reference exit temperature (T _et ). After the determination is made, the carbon-containing raw material is input (S721) and re-strained (722) for heating, and it is determined whether the carbon-containing raw material is input to the converter (S730).

When the carbon-containing raw material is input in the operation step before the steelmaking, the predicted nitrogen concentration (N _e ) becomes equal to or higher than the reference nitrogen concentration (N _t ), or when the carbon-containing raw material is input during the blow, or the end point molten steel temperature ( When T _em ) is less than the standard exit temperature (T _et ), it is the case that the carbon-containing raw material is added for heating.

Accordingly, if the predicted nitrogen concentration (N _e ) during the blow was higher than the reference nitrogen concentration (N _t ) or less than the exit temperature (T _et ) based on the end molten steel temperature (T _em ), it is determined that the carbon-containing raw material was added. In this case, the input control unit 430 operates the second hopper 600b to inject ferro silicon into the converter before going out (S820), and thereafter descends the molten steel.

Conversely, when the predicted nitrogen concentration (N _e ) during blow was less than the reference nitrogen concentration (N _t ), and the end point molten steel temperature (T _em ) satisfies the reference exit temperature (T _et ), carbon-containing raw materials were not added. I judge it. In this case, the input control unit 430 does not operate the second hopper 600b, and immediately lifts the molten steel.

When ferro silicon (FeSi) is added, oxygen and Si in CO of the slag react to become SiO ₂ , and oxygen and Si in CO of the slag react, thereby bursting the CO bubble. Accordingly, the volume of the slag decreases, and the slag that has been expanded to near the furnace port 120 descends to the lower portion of the exit port 130.

In the introduction of ferrosilicon (FeSi) into the converter before exiting, it is preferable to inject ferrosilicon (FeSi) from 0.03% to 0.07% of the amount of molten iron in the converter. For example, when the molten iron content in the converter is 280 tons (tons), it is preferable to add ferro silicon at 100 kg to 200 kg.

When the ferro silicon (FeSi) is input to less than 0.03% of the molten metal in the converter, the volume of the slag is not sufficiently reduced, so that the slag may not go down to the lower portion of the outlet 130. Accordingly, when the converter is inclined by 60 ° or more for exiting, a problem in which slag comes out of the exiting port 130 may occur. Conversely, when ferro silicon (FeSi) is added to exceed 0.07% of the dissolved amount in the converter, the basicity of the slag is lowered, and as the slag is deoxidized, P ₂ O ₅ in the slag is reduced to P and recovered into molten steel. May occur.

Therefore, in the embodiment, ferro silicon (FeSi) is added in an amount of 0.03% to 0.07% of the molten iron in the converter. Thus, it is possible to sufficiently reduce the volume of the expanded slag before going out. Therefore, even if the converter is inclined by 60 ° or more for exiting, the slag does not escape to the exiting port 130.

Hereinafter, with reference to Table 1, a description will be given of the residence time of molten steel in the converter and whether or not the component is separated in the converter refining method according to Comparative Examples and Examples.

The molten iron doses of the first to ninth comparative examples and the first to third examples are the same at 280 t.

In the first to third comparative examples, a sedative agent, which is a raw material of mixed waste pulp sludge, limestone, etc., is added to the converter prior to the river, and a slag port is disposed outside the converter to remove the slag before the river.

In addition, the fourth to ninth comparative examples and the first to third examples are cases in which ferro silicon was introduced into a converter before going out.

Here, the fourth to sixth comparative examples are cases in which the amount of ferrosilicon injected is less than 0.03% of the molten metal in the converter, that is, less than 100 kg, and double-casting and exclusion using slag ports are used. In the double elevating, when the converter is tilted for the molten steel, the slag comes out through the furnace port 120, and after re-establishing the converter, the slag port is partially excluded, and then the converter is tilted again for the molten steel Means

In addition, the seventh to ninth comparative examples are cases where the amount of ferrosilicon exceeded 0.07% of the molten iron in the converter, that is, exceeded 200 kg. In the first to third embodiments, the amount of ferro silicon injected is 0.03% to 0.07% of the molten iron in the converter, that is, 100 kg to 200 kg.

In the case of the third comparative example, the sixth comparative example, the ninth comparative example and the third example, re-straining was performed.

division Before class
Input raw material Before class
Input amount of input raw material (kg) Retake
Whether Residence time of molten steel in converter Remark Comparative Example 1 sedative 500 No odor 5 minute, 32 seconds Slag pot exclusion Comparative Example 2 sedative 1000 No odor 6 minute, 12 seconds Slag pot exclusion Comparative Example 3 sedative 1500 Retake 8 minute, 32 seconds Slag pot exclusion Comparative Example 4 FeSi 55 No odor 6 minute, 48 seconds Double entry and slag port exclusion Comparative Example 5 FeSi 77 No odor 6 minute, 58 seconds Double entry and slag port exclusion Comparative Example 6 FeSi 84 Retake 8 minute, 56 seconds Double entry and slag port exclusion Comparative Example 7 FeSi 235 No odor 1 minute, 38 seconds P off Comparative Example 8 FeSi 315 No odor 1 minute, 42 seconds P off Comparative Example 9 FeSi 357 Retake 3 minute, 12 seconds P off Embodiment 1 FeSi 134 No odor 1 minute, 39 seconds - Example 2 FeSi 156 No odor 1 minute, 28 seconds - Third embodiment FeSi 187 Retake 3 minute, 24 seconds -

Referring to Table 1, in the case of the first to third comparative examples, as described above, sedatives were added to the converter before going out. However, the slag volume could not be sufficiently reduced, and the soothing effect was weak, and an operation in which some slag was first excluded using a slag pot had to be performed. Therefore, in the case of the first to third comparative examples, the residence time in molten steel in the converter was longer than 5 minutes.

In addition, in the case of Comparative Examples 4 to 6, ferro silicon was added to the converter prior to the steelmaking, but the amount of the input was small to less than 0.03% (ie, less than 100 kg) of the molten metal in the converter, so that the slag volume could not be sufficiently reduced. Therefore, the double tapping was forced to be carried out, and at this time, the operation of excluding some slag first using the slag port had to be carried out. Accordingly, in the case of Comparative Examples 4 to 6, the residence time of molten steel in the converter was longer than 5 minutes.

On the other hand, in the case of the 7th to 9th comparative examples, ferro silicon was introduced into the converter before steeling, so that the slag volume could be sufficiently reduced, and accordingly, the molten steel residence time in the converter could be reduced compared to the 1st to 6th comparative examples. However, the amount of ferro silicon

As the amount exceeded 0.03% to 0.07% (ie, exceeding 200 kg) of the dissolved dose, a problem occurred in which slag was deoxidized and P ₂ O ₅ in the slag was reduced to P to be replaced with molten steel. Accordingly, a problem occurs in which P in the molten steel deviates from the target phosphorus concentration (that is, out of P).

However, 0.03% to 0.07% of the molten iron dose, that is, in the case of the first to third examples in which 100 kg to 200 kg of ferro silicon is added, the slag volume can be sufficiently reduced, so there is no need for exclusion using the slag port, and the residence time of molten steel is reduced. It could be reduced compared to the first to sixth comparative examples, and P separation was not generated as in the seventh to ninth comparative examples.

Thus, according to the embodiment of the present invention, even if the volume of the slag is expanded by injecting the carbon-containing raw material during the refining of the converter 100, it is possible to effectively reduce the slag volume by introducing ferro silicon (FeSi) before steeling. Therefore, as in the prior art, after the slag is pre-excluded with the slag port before the steel is discharged, the molten steel can be immediately discharged without going into the molten steel.

Therefore, when using the slag pot as in the prior art, there is no problem that the temperature of the molten steel decreases, so it is necessary to adjust the temperature of the molten steel to a temperature of 20 ° C to 30 ° C higher than the standard exit temperature (T _et ) when the carbon raw material is introduced. There is no In addition, since the slag pre-working material is omitted, there is no problem that the continuous casting time is delayed.

In addition, since no slag pre-column using a slag port is used, the time for the molten steel to stay in the converter 100 can be shortened. Therefore, erosion in the converter can be reduced as compared to the prior art.

100: converter 120: Nogu
130: Exit

Claims (15)

A process for preparing molten steel by blowing oxygen into the converter and blowing the molten iron in the converter;
Predicting the end point nitrogen concentration (N _e ) during the blow and determining whether to input the carbon-containing raw material into the converter according to the predicted result;
After the blow, measuring the end point molten steel temperature (T _em );
Determining whether to input carbon-containing raw materials into the converter according to whether the measured end point molten steel temperature (T _em ) satisfies a reference exit temperature (T _et );
Determining whether ferro silicon is injected into the converter before the steel is discharged according to whether the carbon-containing raw material is injected;
A step of elevating the molten steel from the converter;
Converter refining method comprising a. The method according to claim 1,
The process of predicting the end point nitrogen concentration (N _e ) during the blow,
Measuring the temperature and carbon concentration of the molten iron during the blow; And
Predicting the end point nitrogen concentration (N _e ) using the measured temperature, carbon concentration, end point target carbon concentration (C _et ), and the reference exit temperature (T _et );
Converter refining method comprising a. The method according to claim 2,
The process of determining whether to input the carbon-containing raw material into the converter according to the prediction result,
Determining whether the predicted end point nitrogen concentration (N _e ) is less than a reference nitrogen concentration (N _t ); And
When the predicted end point nitrogen concentration (N _e ) is greater than or equal to the reference nitrogen concentration (N _t ), introducing a carbon-containing raw material into the converter;
Converter refining method comprising a. The method according to claim 3,
When the time point at which the blow-out ends after the start of the blow-off is regarded as a 100% time point, a time point at which 70 to 80% from the time point at which the blow-off is started is called a dynamic time point,
In measuring the temperature and carbon concentration of the molten iron during the blow, measured at the dynamic time point, the temperature and carbon concentration of the molten iron measured during the blow are respectively the dynamic temperature (T _D ) and the dynamic carbon concentration (C _D ). And
The process of determining whether the predicted end point nitrogen concentration (N _e ) is less than the reference nitrogen concentration (N _t ),
Calculating a first required oxygen amount (0 ₁ ), which is the amount of oxygen required from the dynamic time point to the end of the blow, to achieve the reference exit temperature (T _et ) using the dynamic temperature (T _D );
Calculating a second required oxygen amount (O ₂ ), which is the amount of oxygen required from the dynamic time point to the end of the blow, to achieve the end target carbon concentration (C _et ) using the dynamic carbon concentration (C _D );
Any one of the first required amount of oxygen (O ₁ ) and the second required amount of oxygen (O ₂ ) is added to the amount of oxygen blown from the start of the blow to the dynamic time, and the amount of oxygen ( _D ) is blown from the start of blow A process of calculating an end point oxygen amount (O _e ), which is an amount of oxygen to be taken up to the end point;
Setting a reference oxygen amount (O _t ) by adding the second required oxygen amount (O ₂ ) and 400 Nm ³ ;
It is determined whether the value obtained by subtracting the dynamic oxygen amount O _D from the end oxygen amount O _e is equal to or less than the reference oxygen amount O _t , and the predicted end point nitrogen concentration N _e is the reference nitrogen concentration ( N _t ) or less;
Converter refining method comprising a. The method according to claim 4,
In determining whether the end point nitrogen concentration (N _e ) is less than the reference nitrogen concentration (N _t ),
When the value obtained by subtracting the dynamic oxygen amount O _D from the endpoint oxygen amount O _e is equal to or less than the reference oxygen amount O _t , it is determined that the endpoint nitrogen concentration N _e is less than the reference nitrogen concentration N _t ,
When the value obtained by subtracting the dynamic oxygen amount O _D from the end oxygen amount O _e exceeds the reference oxygen amount O _t , the end point nitrogen concentration N _e is equal to or greater than the reference nitrogen concentration N _t Judging converter refining method. The method according to claim 4,
Whether the value obtained by subtracting the dynamic oxygen amount O _D from the end oxygen amount O _e is equal to or less than the reference oxygen amount O _t , and subtracting the dynamic oxygen amount O _D from the end oxygen amount O _e A converter refining method for predicting the end point nitrogen concentration (N _e ) according to a deviation between a value and the reference oxygen amount (O _t ). The method according to claim 6,
A converter refining method for determining an input amount of the carbon-containing raw material according to a difference between a value obtained by subtracting the dynamic oxygen amount (O _D ) from the end point oxygen amount (O _e ) and the reference oxygen amount (O _t ). The method according to claim 2,
In the determination whether or not to input the carbon-containing raw material into the converter, depending on whether the measured end point molten steel temperature (T _em ) satisfies the reference exit temperature (T _et ),
When the measured end point molten steel temperature (T _em ) is less than the reference exit temperature (T _et ), a converter refining method of introducing a carbon-containing raw material into the converter. The method according to any one of claims 1 to 8,
In introducing the ferro silicon, a converter refining method in which the ferro silicon is introduced at 0.03% to 0.07% of the molten iron amount in the converter. A converter having an interior space;
A main lance capable of blowing oxygen into the converter so as to blow the molten iron in the converter;
During the blow, a prediction unit for predicting the end point nitrogen concentration (N _e );
A precipitation determination unit that compares the measured end point molten steel temperature (T _em ) and the reference exit temperature (T _et ) measured at the blown end point to determine whether or not the molten steel can go out;
An input control unit for determining whether ferro silicon is injected into the converter according to the predicted end point nitrogen concentration (N _e ) in the prediction unit and whether or not precipitation is possible in the precipitation determination unit;
A second hopper in which the ferro silicon is stored;
Including,
The input control unit operates the second hopper so that ferro silicon is introduced into the converter before the steel is discharged according to the predicted end point nitrogen concentration (N _e ) in the prediction unit and whether the steel can be discharged from the steel determination unit. Converter refining device to control the. The method according to claim 10,
A converter refining apparatus including a first hopper in which carbon-containing raw materials to be introduced into the converter are stored, according to the predicted end point nitrogen concentration (N _e ) predicted by the predicting unit and the result of determining whether or not it is possible to exit the determining unit. The method according to claim 11,
The input control unit, when the end point nitrogen concentration (N _e ) predicted by the prediction unit is determined to be higher than the reference nitrogen concentration (N _t ) and the end point molten steel temperature (T _em ) in the exit determination unit, the reference exit temperature (T) _et ) In at least one of the cases determined to be less than, the converter refining device for controlling the operation of the second hopper so that ferro silicon is introduced into the converter before the steel is discharged. The method according to claim 11,
The input control unit, when the end point nitrogen concentration (N _e ) predicted by the prediction unit is determined to be higher than the reference nitrogen concentration (N _t ) and the end point molten steel temperature (T _em ) in the exit determination unit, the reference exit temperature (T) _et ), a converter refining device that controls the operation of the first hopper so that a carbon-containing raw material is introduced into the converter. The method according to claim 11,
In the prediction unit, in predicting the end point nitrogen concentration (N _e ),
A converter refining apparatus for predicting the end point nitrogen concentration (N _e ) using the temperature, carbon concentration, end point target carbon concentration (C _et ), and the reference exit temperature (T _et ) of the molten iron measured during the blow. The method according to any one of claims 11 to 14,
The input control unit controls the operation of the second hopper, and converts the ferro silicon into an amount of 0.03% to 0.07% of the molten iron amount into the converter.

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