JPH07173516A - Operation of converter - Google Patents

Abstract

PURPOSE:To prevent the obstructing factors in the operation, such as insufficient melting and slopping of slag, by continuously measuring the temp. of molten metal in a converter, estimating the transition of [Si] concn. in the molten metal and adjusting the supplying speed of refining material. CONSTITUTION:An optical fiber is inserted into the molten metal in the converter and the temp. of the molten metal is measured in continuous or optional timing by the optical fiber temp. measuring instrument containing a means for supplying the fiber by this erosion. The transition of [Si] concn. in the molten metal is estimated from the temp. raising speed to calculate (SiO2) producing speed. As the refining material, the one having oxide, hydroxide or carbonate of Ca or Ba as the main component is used. The charging speed of the refining material is adjusted so that the adding quantity of the refining material during adding the refining material into the converter transits in the range of 2.5-4.5 times of the produced quantity of (SiO2). By this method, the obstructing factors in the operation, such as the insufficient melting and the slopping of the slag, are prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention supplies oxygen to hot metal containing [Si] to remove [Si] and [C], and
The present invention relates to a converter operating method in which a lime-based refining agent is added to adjust the concentration of one or more components of [P], [Mn], [V], and [Cr].

[0002]

2. Description of the Related Art The main purpose of a converter is [C] in hot metal.
Is reduced to a predetermined concentration by oxidative removal using oxygen. At the same time, by adding a refining agent such as quick lime, [P], [Mn],
It is generally performed to control the oxidation / reduction reaction of component elements such as [V] and [Cr] to adjust the concentration. In the converter process, the optimum timing and speed for adding oxygen and refining agent are determined based on the transition of the temperature and components of the metal bath. Since continuous measurement was difficult, it was decided based on the estimation by model calculation as disclosed in Japanese Patent Laid-Open No. 4-124211.

This model calculation generally estimates the reaction rate of desorption [Si] or the like based on the conditions such as the intermittent temperature and component measured values before or during the treatment and the oxygen supply rate. is there. However, it is difficult to estimate the transitions of temperature and components with sufficient accuracy because the reaction in the converter furnace changes depending on the conditions such as the agitation status and the components of the charging materials, and oxygen and refining agents are added. Timing and speed were not always optimal.

[0004]

In the conventional converter treatment, the temperature and components were measured intermittently, so that the timing and speed of adding oxygen and refining agent were not sufficient. For this reason, slag melting failure due to an excessive refining agent addition rate and operation inhibition such as sloping due to an excessive oxygen supply rate occurred. In the former case, when the rate of addition of the refining agent mainly composed of a basic oxide such as (CaO) is too fast with respect to the rate of generation of (SiO ₂ ) by the oxidation of [Si] contained in the hot metal, the slag The reason is that the melting point becomes high, and the latter is the oxidation in the slag when oxygen is supplied at an excessive rate with respect to the amount consumed for the oxidation of [Si] and [C] contained in the hot metal. This is due to the high iron concentration.

In order to improve the accuracy of the timing of adding oxygen and refining agent and the accuracy of the addition rate and solve these problems, continuous measurement of temperature and components is effective. Also, the temperature during the processing of the converter rises due to the heat of oxidation of [C], [Si], etc. Therefore, if either the temperature or the component can be measured continuously, the other can be estimated accurately. Is. However, in the past, a practical measuring device capable of continuously measuring the temperature or composition of the molten metal has not been developed, so an optimum operating method of the converter has not been obtained.

The present invention has been made to solve the above problems. Since a continuous temperature measuring device capable of continuously measuring the molten metal temperature in the converter has been developed this time, the developed continuous temperature measuring device is used. An object of the present invention is to obtain an operating method of a converter capable of optimally adjusting the supply rates of the refining agent and oxygen and preventing the operation inhibition such as defective melting of slag and sloping at low cost.

[0007]

According to a first aspect of the present invention, there is provided a converter operating method in which oxygen is blown from either an upper blowing lance or a tuyere provided in a furnace body or both in the converter. In an operating method for refining a molten metal, an optical fiber is inserted into the molten metal, and an optical fiber temperature measuring device including means for supplying the melt loss is used to measure the temperature of the molten metal continuously or at any timing, By estimating the transition of [Si] concentration in the molten metal from the temperature rise rate (SiO ₂ )
The measurement and calculation process for calculating the production rate, and the ratio of the refining agent charging rate during the addition of the refining agent into the converter and the calculated (SiO ₂ ) production rate are set to a target value within a predetermined range. And an adjusting step of adjusting the refining agent charging speed.

A converter operating method according to claim 2 of the present invention is the converter operating method according to claim 1, wherein the refining agent is calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, or hydroxide. Using barium or barium carbonate as a main component, the addition amount of the refining agent during addition of the refining agent into the converter is (Si
The method has an adjusting step of adjusting the refining agent charging speed so that the amount of O ₂ ) produced is in the range of 2.5 times or more and 4.5 times or less.

[0009]

In the invention according to claim 1, in the operating method in which oxygen is blown from the upper blowing lance and the tuyere provided in the furnace body or both in the converter, the molten metal is measured and calculated. In the step, the temperature of the molten metal is measured continuously or at an arbitrary timing by using an optical fiber temperature measuring device including means for inserting an optical fiber into the molten metal and supplying the melt loss, and the molten metal is measured from the temperature rising rate. Medium [S
i) The (SiO ₂ ) generation rate is calculated by estimating the transition of the concentration. In the adjusting step, the refining agent charging speed during the addition of the refining agent into the converter and the calculated (Si
The refining agent charging rate is adjusted so that the ratio with the O ₂ ) generation rate becomes a target value within a predetermined range.

In the invention according to claim 2, as the refining agent in the invention according to claim 1, any one of calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide or barium carbonate is mainly used. In the adjustment process, the amount of refining agent added during the refining agent addition in the converter stayed within the range of 2.5 times or more and 4.5 times or less of the (SiO ₂ ) production amount. Adjust the refining agent dosing speed so that

[0011]

EXAMPLE FIG. 4 is a schematic view of the equipment of a 300t upper-bottom blowing converter in which the operating method of the converter according to the present invention is carried out. In the figure, reference numeral 20 denotes a temperature measuring nozzle for inserting an optical fiber into the converter 200, which is also called a temperature measuring tuyere. 100 is an optical fiber temperature measuring device as an example of a continuous temperature measuring device,
This is an apparatus including means for inserting an optical fiber into the molten metal in the converter 200, constantly sending out a new optical fiber by the amount of the melted loss, and continuing the supply.

Reference numeral 200 is a converter, and 300 is a main lance. Oxygen is supplied from the upper part for controlling blowing,
Also, it is possible to move up and down with a wire. Four
Reference numeral 00 is a sublance, and a probe including a temperature measuring element (for example, a thermocouple) is provided at the tip of the sublance, and similarly, it can be moved up and down by a wire. Reference numeral 500 denotes an auxiliary raw material hopper, which stores iron ore, mill scale, and the like, and these are added as a coolant during the blowing process. Reference numeral 600 is an exhaust gas analyzer. Since the development of the optical fiber temperature measuring device 100 has made it possible to realize a continuous temperature measuring device having durability, the optical fiber temperature measuring device 100 will be described first.

FIG. 5 is a block diagram showing the configuration of the optical fiber temperature measuring device of FIG. In the figure, 10 is an optical fiber supply device, which is a metal tube coated optical fiber 11,
The motor 12, the roller 13, the feed controller 14, the feed speed detector 15, the optical fiber drum 16, and the radiation thermometer 17 are included. Reference numeral 20 is a temperature measuring nozzle for inserting the metal tube coated optical fiber 11 into the furnace. 21
Is an optical fiber guide that is connected to the temperature measuring nozzle 20, and allows the metal tube coated optical fiber 11 to pass therethrough.
Nozzle clogging prevention gas is supplied. Reference numeral 30 is a nozzle clogging prevention gas supply device, and pressure / flow rate regulators 31, 32,
The supply gas controller 33, the supply gas generation unit 34, and the gas pressure detector 35 are included. And the optical fiber temperature measuring device 100 is the above optical fiber supplying device 10,
It is composed of a temperature measuring nozzle 20, an optical fiber guide 21, and a nozzle clogging prevention gas supply device 30.

A temperature measuring device 100 using an optical fiber shown in FIG.
When measuring the temperature of the molten metal in the converter 200, the tip of the metal tube coated optical fiber 11 is directly inserted into the molten metal or slag in the furnace together with the nozzle clogging prevention gas (for example, nitrogen gas N ₂ ), This metal tube coated optical fiber 11
Since the tip portion of the fiber melts due to high temperature, continuous temperature measurement is possible by continuously sending out a new optical fiber by the melted amount and continuing the supply.
Here, the structure in which the optical fiber is covered with the metal tube is because the pressing pressure by the roller and the pressure of the nozzle clogging prevention gas are applied to the optical fiber when the optical fiber is fed into the furnace by the optical fiber supply device 10.
This is to secure the strength against this pressurization and to protect the internal optical fiber.

A stainless steel tube, for example, is used as the metal tube for coating the optical fiber. Since the melting point of this stainless steel is about 1400 to 1430 ° C., it does not melt immediately even when it is inserted into high temperature molten steel, and protects the optical fiber for several seconds. In this embodiment, the optical fiber is also 160
Since it is made of quartz glass having a softening point of 0 ° C. or higher, it can maintain its shape without melting for a short time. Metal tube coated optical fiber 1 in this embodiment
1 has an outer diameter of 1.2 mm.

The temperature measuring nozzle 20 includes, for example, one made of brick or ceramics, one made of a single metal tube, or one made of a single metal tube having a ceramic inside, and the like. Between the outer diameter of the inner temperature measuring nozzle and the inner diameter of the outer metal tube, a metal tube is concentrically provided on the outside of the temperature measuring nozzle constituted by the metal single tube or the metal single tube whose inside is ceramics. There is also a double-tube structure in which the void provided in is connected to the nozzle clogging prevention gas supply device 30.

One end of the temperature measuring nozzle 20 is in contact with the molten metal, and the other end is airtightly coupled to the optical fiber guide 21. The metal tube coated optical fiber 11 is inserted from the optical fiber guide 21 side and inserted into the molten metal. Further, the inner diameter of the temperature measuring nozzle 20 and the optical fiber 11 coated with the metal tube
A gap is provided between the outer diameter and the outer diameter of the nozzle, and the nozzle clogging prevention gas is blown into the gap through the optical fiber guide 21. In this embodiment, as the temperature measuring nozzle 20, a single metal tube having an inner diameter of 3.0 mm and an outer diameter of 5.0 mm was used.

The optical fiber guide 21 measures the metal tube covered optical fiber 11 continuously sent from the optical fiber supply device 10 together with the nozzle clogging prevention gas supplied from the nozzle clogging prevention gas supply device 30 and the temperature measuring nozzle 20.
It has a function of sending out to the molten metal in the converter 200 through.

One end of the optical fiber guide 21 is hermetically connected to one end of the temperature measuring nozzle 20 which is not in contact with the molten metal, and the other end thereof can pass the metal tube coated optical fiber 11, but the nozzle clogging prevention gas is used as the optical fiber supply device 10. In order to prevent leakage to the side, a highly airtight structure is provided with, for example, a double seal. In addition, in the gap provided between the inner diameter of the optical fiber guide 21 and the outer diameter of the metal tube coated optical fiber 11, the nozzle clogging prevention gas supply device 3
Pipes from 0 are connected and the gas is supplied.
In this way, the optical fiber guide 21 is used for the temperature measuring nozzle 20.
Although it is composed of another member, the function of sending the optical fiber together with the nozzle clogging prevention gas into the converter 200 is exactly the same, and in a broad sense, it can be regarded as a member that constitutes a part of the temperature measuring nozzle 20. You can

From the temperature measuring nozzle 20 airtightly connected to the optical fiber guide 21, the metal tube coated optical fiber 11 is introduced.
The nozzle clogging prevention gas is blown into the molten metal in the furnace together with the discharge. In this case, since bubbles are generated in the floating region of the nozzle clogging prevention gas in the molten metal, if the tip of the metal tube-covered optical fiber 11 enters the bubble generation region, the temperature measurement accuracy will deteriorate. Therefore, for example, the temperature measuring nozzle 20 is installed with an inclination angle (for example, about 30 degrees) downward from the horizontal plane, and the metal tube coated optical fiber 11 is installed.
It is desirable to prevent the tip of the gas from entering the floating region of the gas.

The optical fiber supply device 10 has a function of continuously or intermittently feeding the metal tube coated optical fiber 11 into the converter 200 via the optical fiber guide 21 and the temperature measuring nozzle 20. Therefore, the feed controller 1
Reference numeral 4 denotes a metal tube-coated optical fiber 1 which drives the motor 12 and is wound in advance in the optical fiber drum 16.
1 is sent out. In this case, the feed speed detector 15 detects the feed speed of the optical fiber and controls the feed speed to a predetermined value based on the detected value.

In this embodiment, the continuous feeding speed of the optical fiber is 5 mm / sec, and the intermittent feeding speed is 10 mm / sec for 10 seconds and then 20 seconds.
The operation of stopping for a second is repeated. This optical fiber is sent out because the tip of the metal tube-coated optical fiber 11 that is inserted into the furnace together with the nozzle clogging prevention gas is melted and lost with the lapse of time. ) To constantly supply new optical fiber. And continuous supply of this new optical fiber enables continuous temperature measurement.

The feed rate detector 15 can obtain the feed rate from the rotation angle of the sensor roller within a unit time, for example, and this detection signal is used as a feed gas controller in the feed controller 14 and the nozzle clogging prevention gas supply device 30. 33. And this feed rate detector 1
Depending on whether or not the detected value of 5 is within the normal range, it is possible to determine the difficult state of optical fiber delivery. For example, if the tip of the temperature measuring nozzle 20 becomes clogged, the feed rate will decrease. The feed controller 14 stops the drive of the motor 12 when the feed speed falls below the normal range to prevent the device from malfunctioning.

The optical fiber temperature measuring device 100 uses the principle of measurement that the absolute temperature can be calculated from the radiation spectrum distribution if the black body radiation condition is satisfied. Therefore, the spectrum light emitted from the molten metal is input from the tip of the metal tube-coated optical fiber 11 inserted in the furnace, and the spectrum light propagates in the optical fiber and is input to the radiation thermometer 17.

The radiation thermometer 17 includes, for example, a two-color thermometer for determining the temperature by comparing the luminance outputs of two wavelengths and an infrared radiation thermometer for directly determining the temperature from the luminance output of the radiated light. The temperature is calculated from the signal according to each measuring method, and the calculated temperature signal is output as an electric signal and supplied to, for example, a recorder (not shown).

The gas supplied from the nozzle clogging prevention gas supply device 30 to the optical fiber guide 21 is an inert gas (nitrogen gas in this example), an oxidizing gas (oxygen gas in this example), an inert gas and an oxidizing gas. Any one of the three kinds of gases (mixing ratio of which can be variably set) is selected and used. Also, the selection of this gas type is
The operation is performed manually or automatically depending on the difficulty of sending out the metal tube coated optical fiber 11 by the optical fiber supply device 10. The example of FIG. 5 shows a case where this gas type is automatically selected.

The supply gas controller 33 in the nozzle clogging prevention gas supply device 30 detects the detection signal of the gas pressure detector 35 and the feed rate detector 1 in the optical fiber supply device 10.
5 detection signals are input, one of the three types of nozzle clogging prevention gas is automatically selected according to the values of these two detection signals, and the control signals based on the selection results are respectively pressure / flow rate. Supply to regulators 31 and 32.

The pressure / flow rate adjusters 31 and 32 include a pressure adjuster, a flow rate adjuster, a control valve, etc., and input nitrogen gas and oxygen gas respectively as pressure and flow rate according to a control signal. The gas is supplied to the supply gas generation unit 34. In the supply gas generation unit 34, either nitrogen gas, oxygen gas or a mixed gas of both is generated at a predetermined pressure and is supplied to the optical fiber guide 21 from here.

The gas pressure detector 35 includes the supply gas generator 3
4 detects the gas pressure supplied to the optical fiber guide 21, and supplies this detected value to the supply gas controller 33. This is because when the tip of the temperature measuring nozzle 20 is clogged, the amount of gas supplied is reduced and the detected value of gas pressure rises. Therefore, it is necessary to measure whether the detected value is within the normal range or not. This is because the clogging state of the tip of the warm nozzle 20 can be determined. The supply gas controller 33 determines the clogging state of the tip of the temperature measuring nozzle 20 based on the detection value of the supply gas pressure and the detection value of the optical fiber feeding speed, and automatically selects the gas type.

In the embodiment of FIG. 5, the supply gas controller 33 determines that the temperature measuring nozzle 20 is in the case where the optical fiber feed speed detection value and the supply gas pressure detection value are in the normal range.
In order to protect the metal tube-coated optical fiber 11 inserted in the converter 200, an inert gas (nitrogen gas in FIG. 5) having a cooling effect is selected as the nozzle clogging prevention gas. However, when the flow rate of the inert gas is too high, a mushroom (a spongy mass in which the molten metal is partially solidified) is generated at the tip of the temperature measuring nozzle 20, and the insertion of the metal tube-coated optical fiber 11 is prevented. become unable.

On the contrary, if the flow rate of the inert gas is too low, the molten metal is inserted into the tip of the temperature measuring nozzle 20. In the example of FIG. 5, the amount of nitrogen gas blown into the optical fiber guide 21 adjusted by the pressure / flow rate adjuster 31 is 3.0.
Nm ³ / Hr (833 cc / sec), and the linear flow velocity of the gas at the tip of the temperature measurement nozzle 20 is 50 to 500 Nm / s.
The value is adjusted to be the optimum value within the range of ec. Further, in order to secure this linear flow velocity, it is most preferable that the ratio of the inner diameter of the temperature measuring nozzle 20 to the outer diameter of the metal tube coated optical fiber 11 is in the range of approximately 1.5 to 3.5.

Even if the temperature is measured by blowing nitrogen gas as described above, the feed rate of the optical fiber is reduced due to the generation of mushrooms at the tip of the temperature measuring nozzle 20 in the converter 200, and the supply gas pressure is increased. I have something to do. In this case, the supply gas controller 33 selects, as the nozzle clogging prevention gas, a mixed gas in which oxygen gas is mixed with nitrogen gas at a predetermined ratio. Although the mixing ratio of the mixed gas can be variably set, normally, from the viewpoint of protection of the temperature measuring nozzle 20, it is preferable that the mixing ratio of the oxygen gas is limited to 50% at the maximum.

The supply gas controller 33 controls the pressure / flow rate regulators 31 and 32 based on the selection result to generate a mixed gas having the predetermined mixing ratio, and blows the mixed gas into the optical fiber guide 21 to remove mushrooms or the like. It can be dissolved to prevent its adhesion. However, due to strong mushroom adhesion and the like, the blow rate of the mixed gas may not return the feed rate of the optical fiber and the supply gas pressure to the normal range. In this case, therefore, the supply gas controller 33, as the nozzle clogging prevention gas, Oxygen gas is selected only for a short time, and the dissolution by this oxygen gas is performed.

In the equipment outline diagram of the converter shown in FIG. 4, the optical fiber temperature measuring device 100 as a continuous temperature measuring device carried out continuous temperature measurement under the following measuring conditions. (1) Temperature measuring nozzle, model: Metal single tube nozzle, length: about 1000 mm Inner diameter / outer diameter of nozzle: 3.0 mm / 5.0 mm Material: SUS304 (2) Optical fiber, structure: Stainless tube outer diameter: 1 0.2 mm (3) Gas suction, type: Nitrogen gas Suction amount: 3.0 Nm ³ / Hr Blow-off flow rate: 328 Nm / sec (4) Optical fiber feed rate: 5 mm / sec (continuous) or 10 mm / sec (intermittent)

The object of the present invention is to measure the temperature of the hot metal continuously or at an arbitrary timing by using the optical fiber temperature measuring device, and to estimate the [Si] concentration transition in the hot metal from the temperature rising rate (SiO). ₂ ) It is solved by calculating the production rate and adjusting the supply rates of the refining agent and oxygen.

The calculation process according to the present invention is formulated as follows. [Si] in the hot metal reacts with oxygen to generate heat of oxidation according to the following equation (1). [Si] + O ₂ = (SiO ₂ ) + (heat of oxidation) (1) At this time, in order to estimate the [Si] concentration transition in the hot metal,
The following equations (2) and (3) are used.

[0037]

[Equation 1]

[0038]

[Equation 2]

Here, T is the time (seconds) after the start of the converter treatment [Si] _t is the [Si] concentration [%] [Si] ₀ in the hot metal at the time T = t [Si] ₀ is the hot metal at the start of the converter processing [Si] concentration [%] d [Si] / dO ₂ is [S] in the hot metal [S
i] Concentration change ratio [% / (Nm ³ / TON)] dO ₂ / dT is the oxygen supply amount per unit time [(Nm ³
/ TON) / sec] dθ / dO ₂ is the ratio of temperature rise to oxygen supply [° C /
(Nm ³ / TON)].

The above formula (3) is a formula showing the relationship between the temperature change and the [Si] concentration change, and the coefficients A and B are about -0.02 and about 0.15, respectively. It depends on the shape (for example, the specific surface area of the hot metal in the converter) and the like, so it is determined by conducting an experiment in advance. In addition, depending on equipment conditions (agitation strength, etc.), the coefficients A and B
The accuracy may be improved by using as a function of [Si].

In the converter operating method of the present invention, the (SiO ₂ ) generation rate is first calculated in the measurement and calculation steps. In this step, the optical fiber temperature measuring device 10
0, the temperature of the molten metal in the converter during refining is measured continuously or at an arbitrary timing, and the ratio of temperature rise dθ / dO ₂ to the amount of oxygen supplied is determined, and this value and the coefficient A,
Substituting B into equation (3), d [Si] / dO ₂ is calculated. Thus, d [Si] / dO _2, which was conventionally estimated based on the lack of measuring means, is indirectly measured by temperature measurement.

Next performed by the calculation of expression (2) using the d [Si] / dO _2, molten iron at time t from the blowing start a [Si] concentration calculated [Si] _t. Then, the production rate of (SiO ₂ ) can be accurately calculated from the material balance of the equation (1). As a result, the timing and rate of adding the refining agent and oxygen are optimized as described later.

The operating conditions for carrying out the present invention are shown in Table 1 below.

[0044]

[Table 1]

FIG. 2 shows changes in bath temperature and [S
i] A diagram showing an example of transition of concentration, bath temperature is a measured value measured by an optical fiber temperature measuring device, and [Si] concentration is a value obtained by sampling. As shown in FIG. 2, the rate of decrease of the [Si] concentration is unstable due to factors such as non-uniformity of the converter charge, but the rate of change in temperature and [S
i] The rate of change in density has a good correlation.

FIG. 3 is a diagram showing the relationship between the temperature increase per unit oxygen supply amount and the [Si] concentration decrease according to the present invention. D [Si] / dO ₂ and dθ / dO ₂ for a plurality of heats.
The result of actual measurement is shown by +. The error between the value indicated by + in FIG. 3 and the calculated value of the equation (3) is [S
i] Since it is a density estimation error, [S
It can be seen that the error of i] concentration estimation is less than ± 4% of the initial [Si] concentration. In the present invention, the production amount of (SiO ₂ ) could be continuously grasped from the change in the [Si] concentration thus obtained.

In this example, quicklime was used as the refining agent. Table 2 below shows the injection timing and the injection speed of quick lime under the conditions where the hot metal [Si] concentration and the refining agent injection amount are constant.
Various patterns shown in FIG.

[0048]

[Table 2]

FIG. 1 is a diagram showing the undissolved (CaO) concentration in the slag with respect to the ratio of the (CaO) charging rate and the (SiO ₂ ) generation rate according to the present invention, and various quick lime charging patterns shown in Table 2 were carried out. The result is shown. As can be seen in FIG. 1, the continuous addition of quicklime along with the production of (SiO ₂ ) promotes the melting of lime. In particular, undissolved lime can be significantly reduced by adjusting the quick lime charging rate so that the amount of (CaO) is 2.5 times or more and 4.5 times or less of the (SiO ₂ ) production amount. it can.

Therefore, in the converter operating method of the present invention, the amount of the refining agent added during the refining agent addition in the converter is (Si
The refining agent charging rate is adjusted so that the amount of O ₂ ) produced is 2.5 times or more and 4.5 times or less. Further, as the refining agent, calcium oxide, one containing calcium hydroxide or calcium carbonate as a main component (for example, quick lime, limestone, dolomite, etc.), or barium oxide,
It may be one containing barium hydroxide or barium carbonate as a main component.

As a result of carrying out the present invention, the quick lime basic unit is reduced by about 6%, the cost for adjusting the concentrations of [P], [Mn], [V], and [Cr] can be reduced, and sloping can be achieved. It was possible to suppress the operation inhibition such as.

[0052]

As described above, according to the present invention, the temperature of the molten metal is continuously or arbitrarily set by using the optical fiber temperature measuring device including the means for inserting the optical fiber into the molten metal and supplying the melt loss. By measuring the temperature at the timing of, and estimating the transition of [Si] concentration in the molten metal from the temperature rise rate (S
iO ₂ ) generation rate is calculated, and the refining agent charging rate and the above (S
Since the refining agent charging speed is adjusted so that the ratio with the iO ₂ ) generation rate becomes a target value within a predetermined range, it is possible to inexpensively prevent operation inhibition such as defective melting of slag and sloping. I was able to.

Further, according to the present invention, as the refining agent, one containing calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide or barium carbonate as a main component is used, and refining in a converter is performed. The amount of refining agent added during the addition of the agent is 2.5 of the (SiO ₂ ) production amount.
Since the refining agent charging speed was adjusted so that the refining agent charging rate was adjusted so as to change within the range of not less than 4.5 times and not more than 4.5 times, a converter operating method was obtained in which the concentration of the undissolved refining agent in the slag was minimized. .

[Brief description of drawings]

FIG. 1 is a diagram illustrating a (CaO) charging rate and a (Si) according to the present invention.
O ₂ ) undissolved in slag (Ca)
It is a figure which shows O) density.

FIG. 2 is a diagram showing an example of a bath temperature transition and a [Si] concentration transition in a converter process.

FIG. 3 is a diagram showing a relationship between a temperature increase per unit oxygen supply amount and a [Si] concentration decrease according to the present invention.

FIG. 4 is a schematic diagram of a converter operating method 300 according to the present invention.
FIG. 3 is a schematic view of equipment of a top-bottom blowing converter.

5 is a block diagram showing the configuration of the optical fiber temperature measuring device of FIG. 4. FIG.

[Explanation of symbols]

 10 Optical Fiber Feeding Device 11 Metal Tube Covered Optical Fiber 12 Motor 13 Roller 14 Feeding Controller 15 Feeding Speed Detector 16 Optical Fiber Drum 17 Radiation Thermometer 20 Temperature Measuring Nozzle 21 Optical Fiber Guide 30 Nozzle Clogging Prevention Gas Supply 31, 32 Pressure / Flow Regulator 33 supply gas controller 34 supply gas generation unit 35 gas pressure detector 100 optical fiber temperature measuring device 200 converter 300 main lance 400 sublance 500 auxiliary raw material hopper 600 exhaust gas analyzer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiro Kikuchi, 1-2 Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Inventor Shigeru Inoue 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Date Main Steel Pipe Co., Ltd.

Claims (2)

[Claims] 1. An operating method for refining a molten metal by blowing oxygen from either or both of a top blowing lance and tuyere provided in a furnace in a converter, wherein an optical fiber is inserted into the molten metal and the molten metal is melted. By using an optical fiber temperature measuring device including a means for supplying loss, the temperature of the molten metal is measured continuously or at arbitrary timing, and the transition of the [Si] concentration in the molten metal is estimated from the temperature rising rate (SiO ₂ ) The production rate was calculated, and the refining agent charging rate during the addition of the refining agent into the converter was calculated as above (Si
A method for operating a converter, wherein the refining agent charging rate is adjusted so that the ratio with the O ₂ ) generation rate becomes a target value within a predetermined range. 2. A refining agent containing calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide or barium carbonate as a main component is used as the refining agent during addition of the refining agent into the converter. The refining agent charging speed is adjusted so that the amount of the refining agent added is kept in a range of 2.5 times or more and 4.5 times or less of the (SiO ₂ ) production amount. Converter operating method.