JP2018178209A - Tilting type refining apparatus and tilting slag discharging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tilting type refining apparatus and tilting slag discharging method capable of reducing time for slag discharging while minimizing flowing-out of molten metal from a vessel opening when discharging molten slag by tilting a refining vessel while leaving the molten metal in the refining vessel.SOLUTION: The tilting type refining apparatus comprises a detection coil 4 provided in a wall of the refining vessel (converter 1) in contact with a path (discharge path 17) through which molten slag 34 passes when the refining vessel is tilted to discharge the molten slag 34 in the refining vessel, and the detection coil 4 has one or a plurality of conductive coils and includes an AC current applying device 8 for applying an AC current to the detection coil 4, and a detection device 9 for detecting a change in induced electromotive force in the detection coil 4 or a change in impedance of the detection coil. When the molten metal is detected, as a result of detection by the detection device 9, to reach an installed position of the detection coil, a tilting speed of the refining vessel is reduced or the tilting is stopped in response to the detection.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tilting type refining device capable of discharging a molten slag in a refining container by tilting the refining container and a tilting displacement method using the tilting type refining device.

  The hot metal discharged from the blast furnace is subjected to impurity removal refining in a steel making process, adjusted to a predetermined steel component, and made into a slab, and a predetermined steel product is manufactured in a subsequent rolling process. Among impurity removal and refining in the steel making process, dephosphorization and decarburization are mainly performed in a converter. As a method of sequentially performing dephosphorization and decarburization refinement in one converter, a method of performing dephosphorization refinement-discharge of dephosphorization slag-decarburization refinement in this order is known. Hot metal is charged into the converter, and a refining agent such as quicklime is introduced into the converter for dephosphorization to carry out dephosphorization while blowing in pure oxygen. The desiliconation reaction also proceeds during dephosphorization refining. After completion of the dephosphorization refining, the converter is tilted, and while leaving the molten iron in the converter, only dephosphorization slag is discharged from the converter furnace port, and then the converter is stood upright to carry out decarburization refining. At the time of decarburization refining, an additional refining agent may be introduced into the converter, and finishing dephosphorization may be performed. After completion of decarburization and refining, first, the converter is tilted to the side where the steel tapping hole of the converter is provided, and the molten steel is discharged, and then the converter is tilted to the opposite side to remove molten slag (decarburized slag) Discharge. This method is also called double slag method. Since the decarburized slag remaining in the furnace after deburring has dephosphorization ability, it can be used as a dephosphorizing agent in dephosphorization refining of the next charge without discharging the decarburized slag, Method is also called MURC method.

  In the converter smelting of steel, the desiliconization slag is first discharged from the converter when the desiliconization refining is completed, and then the dephosphorizing refining agent such as the lime source is introduced into the converter to remove the high basicity slag. It is also known how to carry out phosphorus refining.

  When performing smelting reduction of iron or ferrochrome using a converter or an electric furnace, the smelting furnace is also tilted to remove slag while leaving molten metal in the furnace after completion of smelting reduction. Discharge the In addition, in the KR method, which is a kind of hot metal preliminary desulfurization refining method, hot metal is contained in a pot type refining vessel (hot metal pot), a desulfurizing refining agent is added, and the hot metal desulfurization refining is performed with a stirrer. In order to prevent the resulfurization of the steel, the treatment to discharge the desulfurization slag by tilting the hot metal ladle is performed.

  With regard to the problems with the methods exemplified above, with the molten metal left in the refining container, tilting the refining container and discharging only the molten slag (tilting and discharging method), the refining container is a converter and the molten iron is The case of refining will be described as an example. Among the molten slag in the converter before the start of the tilting displacement, the ratio of the molten slag discharged from the converter by the displacement is referred to as "displacement rate". The position of the opening (hereinafter also referred to as the “furnace port”) of the converter, which is a refining vessel, is lowered by tilting the converter, and the lower end of the furnace port opening position (hereinafter referred to as “the lower end of the furnace port”) is inside the furnace. Descend to just below the molten slag liquid level, and discharge the molten slag from the furnace port. Since the specific gravity of the molten slag is smaller than that of the molten iron, the molten iron is located in the lower layer in the furnace and the molten slag is located in the upper layer. Therefore, by controlling the tilt of the converter so that the liquid level of the molten iron is located below the lower end of the furnace port, the molten iron in the converter is not discharged but only the molten slag is discharged. However, since the thickness of the molten slag layer in the converter at the time of tilting displacement is not so thick, it is necessary to grasp an appropriate tilting angle in order to secure a high discharge rate while suppressing molten iron outflow. In practice, the method of continuing the tilting of the converter while making the tilting speed extremely low and stopping the tilting when the outflow of the molten iron is visible from the furnace opening is adopted. In this method, the time required for the tilting displacement is long in order to make the tilting speed extremely low, and since the outflow of the molten iron from the furnace opening is confirmed and stopped, the loss of the molten iron can not be avoided.

  If the molten iron can be detected immediately before the molten iron flows out from the furnace opening at the time of tilting and discharging, the discharging time can be shortened and the molten iron loss can be prevented, so the sensing technology is extremely important. Therefore, a technique has been proposed for measurement including the variation of the molten iron outflow limit tilt angle for each charge.

  In Patent Document 1, one electrode is provided on the lower wall near the top end of the slag discharge path of the refining vessel, the other electrode is provided on the lower refining vessel main body, and the conduction current with the molten metal using both electrodes A method is disclosed for detecting the value and obtaining the displacement position tilt angle of the refining vessel. Further, according to Patent Document 2, a plurality of electrodes are inserted at the upper end of the furnace throat slag discharge passage at the time of tilting, and conduction between the electrodes is detected to determine whether the molten material discharged from the furnace throat is metal or slag. Methods are disclosed.

  In Patent Document 3, gas is blown into the vessel from a tuyere provided on the inner wall of the refractory of the refining vessel, a change in back pressure is detected, and arrival of molten metal is judged to obtain a displacement position tilting angle. A method is disclosed. In Patent Document 4, gas is blown into the vessel from the tuyere provided on the inner wall of the refractory of the refining vessel, and the optical spectrum intensity of the specific element contained in the molten slag or molten metal is measured by the optical fiber installed inside the tuyere. A method of measuring and judging the arrival of molten metal to obtain the displacement position tilt angle is disclosed.

Japanese Patent Application Laid-Open No. 05-288479 Unexamined-Japanese-Patent No. 06-201278 gazette Japanese Patent Application Laid-Open No. 06-235585 Japanese Patent Application Laid-Open No. 06-235016 Japanese Patent Application Laid-Open No. 05-018679 JP-A-53-048008

  As a problem when carrying out the sensing technique described in the patent documents 1 to 4, the electrodes, the bubbling tuyere, and the fiber observation part come into contact with the molten metal and the molten slag during the refining in the refining vessel. Inevitably, in order to carry out an accurate measurement, it is necessary to frequently carry out maintenance of removal of bare metal and slag adhered at the time of contact. Therefore, these methods have many problems in terms of productivity and work load.

  In Patent Document 5, when the molten metal is discharged from the tapping hole provided in the wall surface of the molten metal storage container, the transmission / reception sensor coil is embedded so as to face inside the iron skin of the tapping hole, There is disclosed a method of connecting them to a signal processing device and detecting the outflow of slag at the end of tapping on the principle of electromagnetic induction. Patent Document 6 discloses a method of arranging one detection coil to detect a change in impedance of the detection coil. However, the inventions described in these Patent Documents 5 and 6 detect a phenomenon in which the passage material of the tapping hole changes from molten metal to molten slag, and as in the present invention, from the furnace opening at the time of tilting discharge. Is different from the method of preventing the discharge of molten metal. In addition, even when detecting a phenomenon in which the effluent from the tapping hole changes to molten slag, it is known that detection delay actually exists, and the application is restricted.

  The present invention is intended to shorten the discharge time while minimizing the outflow of molten metal from the furnace opening when discharging the molten slag while leaving the molten metal in the refining container while tilting the refining container. It is an object of the present invention to provide a tilt type refining device and a tilt displacement method that can be performed.

That is, the place made into the summary of the present invention is as follows.
(1) In a tilting type refining device capable of tilting the refining vessel, a path through which molten slag passes when the molten slag in the refining vessel is discharged by tilting the refining vessel is referred to as a discharge path, and An alternating current application device having a detection coil in a furnace wall of a refining vessel in contact with the detection coil, the detection coil having one or a plurality of conductive coils, and applying an alternating current to the detection coil; And a detection device for detecting a change in power or a change in impedance of the detection coil.
(2) The tilting and refining apparatus according to (1), wherein a plurality of the detection coils are provided in the discharge path.
(3) The detection coil is accommodated in a coil exchange unit, and the coil exchange unit is detachably mounted in the furnace wall of the refinement vessel from the outside of the refinement vessel. The tilting type refining device described in 2).
(4) In the tilting displacement method using the tilting type refining device according to any one of (1) to (3) above, when tilting the refining container and discharging the molten slag in the refining container Detecting that the molten metal has reached the detection coil installation position from the change in the induced electromotive force or the impedance change detected by the detection device, and decelerating the tilting speed of the refining vessel in response to the detection A tilting displacement method characterized by stopping tilting.
(5) A tilt displacement method using the tilt type refining device according to the above (2) or (3), wherein when the refining container is tilted and the molten slag in the refining container is discharged, the detection device When the arrival of molten metal is detected by the detection device connected to the first detection coil, it is detected that the molten metal has reached the detection coil installation position from the change in the induced electromotive force or the impedance change detected in step A tilting displacement method comprising: decelerating a tilting speed of a container and stopping tilting when the arrival of molten metal is detected by a detection device connected to a second detection coil.

  According to the tilting type refining device and the tilting displacement method of the present invention, when discharging the molten slag while tilting the refining container and leaving the molten metal in the refining container, the molten metal outflow from the furnace opening is minimized. It is possible to shorten the evacuation time.

It is sectional drawing which shows the condition which implements tilting displacement according to this invention, (A) is a case where there are one detection coil, (B) is a case where there are two detection coils. It is a conceptual diagram explaining the case where the detection coil of this invention has two conducting coils, (A) is a figure which shows the combination of a detection coil and each apparatus, (B) is a figure which shows an oscilloscope image. It is a conceptual diagram explaining the case where the detection coil of this invention has one conducting coil. It is a figure which shows an example of the time change of the detected peak value. It is a fragmentary sectional view which shows the state incorporating a detachable detection coil. It is a fragmentary sectional view showing the state before incorporating a removable detection coil, (A) is a refinement device side, (B) shows a coil exchange unit.

  In the present invention, taking the converter as an example of the refining vessel as an example, as an application example in the case of carrying out an intermediate discharge in which molten slag is discharged from the furnace port while molten iron remains in the furnace at the time of molten iron refining in the converter. The description will be made with reference to FIG. Here, in the present invention, the refining vessel is not limited to the converter, and any one of an electric furnace and a pot-type vessel can be adopted as long as it has a tilting function. Various molten irons such as molten steel, hot metal, high alloy steels such as various stainless steels, and molten slag present on the upper surface, which has lower density than molten iron and a negligible electric conductivity compared to molten iron It may be a tilting type refining device that can be utilized at the time of discharge of slag. Moreover, it is applicable also to the double slag method, the hot metal pre-treatment, the smelting reduction, the pan exhausting operation etc. using the said tilting type refinement | purification apparatus.

  The converter 1 can tilt the furnace body about a tilting axis. A furnace port 2 is provided at a position which is upward when the furnace body is upright. At the time of molten metal charging, the furnace port is tilted to the front side of the furnace and molten metal is charged from the furnace port, and then the converter is erected and a pure oxygen top lance is inserted from above through the furnace port to blow oxygen Smelting, desiliconizing, etc.). At the time of middle dumping, as shown in FIG. 1, the furnace port 2 is tilted to the furnace front side 20, and the molten slag 33 (such as dephosphorized slag) is discharged from the furnace port 2 while the molten iron 33 remains in the furnace, The molten slag 34 is accommodated in the slag pan 3 disposed under the furnace. After that, the converter is stood upright, oxygen blowing (decarburization refining, dephosphorization refining, etc.) is performed again, impurity removal refining is performed to the target impurity concentration, the converter is tilted to the back side of the furnace and molten iron (Steeling of molten steel) The molten slag (decarburized slag and the like) remaining in the furnace is left to tilt the converter to the front side of the furnace to be discharged from the furnace port or to be used as a dephosphorizing slag for the next charge.

  The furnace inside shape of the converter 1 generally passes from the bottom when standing up, the furnace bottom 13, the cylindrical furnace belly 14, and the furnace top 15 which becomes an upside-down truncated cone when standing up, and then the furnace top Have a furnace port 2. A path through which the molten slag 34 passes when the molten slag 34 in the refining vessel is discharged by tilting the refining vessel (converter 1) is referred to as a discharge path 17 here. When the converter is tilted to the discharge side (furnace front side 20), the furnace port 2 rotates around the tilting axis. The lowest position of the opening of the furnace port 2 at the time of evacuation is referred to as the furnace lower end 19 here. The furnace inner surface 16 of the furnace upper portion 15 including the furnace lower end portion 19 and the position where the molten slag contacts at the time of discharge forms the discharge path 17.

  In the present invention, the detection coil 4 is provided on the inside of the converter 1 (refining vessel) in contact with the discharge path 17. The detection coil 4 has one or more conductive coils 5. The conductive coil 5 means a coil in which a conductive wire is wound one turn or a plurality of turns.

  The detection coil 4 of the present invention in the detection coil 4 determines whether the molten material existing in contact with the furnace inner surface 16 of the furnace wall 11 near the detection coil 4 is molten slag 34 or molten metal (molten iron 33) It has a function of detecting as a change in induced electromotive force or an impedance change in the detection coil 4. Therefore, detection coil 4 is provided in the furnace wall in contact with discharge path 17 and close to furnace inner surface 16 of the furnace wall, and magnetic lines of force formed by detection coil 4 intersect furnace inner surface 16 of the furnace wall. To set up. The intersection position of the central axis of the detection coil 4 and the furnace inner surface 16 of the furnace wall is referred to as a detection position 18. Specifically, it is preferable that the central axis of the detection coil 4 be provided perpendicular to the furnace inner surface 16 of the furnace wall or at an angle within 45 degrees from the vertical. Moreover, if the space | interval of the detection coil 4 and the furnace inner surface 16 of a furnace wall is 500 mm or less, detection sensitivity is fully securable.

Regarding the detection operation principle of the present invention, first, using the detection coil 4 having two conductive coils 5, the alternating current application device 8 is connected to one of the conductive coils 5 (primary coil 6) to apply an alternating current, The method for detecting the induced electromotive force induced in the secondary coil 7 by connecting the detection device 9 to the conductive coil 5 (secondary coil 7) will be described based on FIG. The positional relationship between the primary coil 6 and the secondary coil 7 may be such that the magnetic field generated by the primary coil 6 passes through the secondary coil 7.
When an alternating current is applied to the primary coil 6 by the alternating current application device 8, an alternating magnetic field 35 passing through the primary coil 6 is generated. Since an induced electromotive force is generated in the secondary coil 7 due to the magnetic field 35 by the primary coil 6, the induced electromotive force can be measured by the detection device 9. If a conductive substance is present within the range of the alternating magnetic field 35 formed by the primary coil 6, the induced current 36 flows in the conductive substance (the molten iron 33) due to the alternating magnetic field 35, as a result, The induced electromotive force induced in the secondary coil 7 is affected by the induced current 36 in the conductive material in addition to the influence by the primary coil 6, so the induced electromotive force detected by the secondary coil 7 changes It will be done. Therefore, by detecting the induced electromotive force of the secondary coil 7 while applying an alternating current to the primary coil 6, it is possible to detect whether or not a conductive substance is present within the alternating magnetic field range of the detection coil 4. Is possible. In the present invention, the timing at which the material of the portion of the furnace wall in contact with the furnace inner surface 16 in the discharge passage 17 of the smelting vessel is replaced by molten slag 34 (low electrical conductivity) with molten iron 33 (high electrical conductivity) It can be detected as a change in the induced electromotive force of the next coil 7. As the alternating current application device 8, either a constant current type or a constant voltage type can be used. At this time, a constant voltage type is preferable as an application type to the primary coil. This is because the magnetic field generated by the applied current is defined by the product (A-turn) of the applied current of the primary coil and the number of turns, and a constant magnetic flux can be maintained, and the impedance detected by the secondary coil This is because it is possible to easily ensure good detection accuracy of the change.

  Therefore, as shown in FIG. 2A, the detection coil 4 having the primary coil 6 and the secondary coil 7 as the conductive coil 5 is embedded in the furnace wall of the discharge path 17 of the converter 1 and the central axis of the detection coil 4 Were placed perpendicular to the furnace inner surface 16 of the furnace wall. An alternating current of constant current was applied to the primary coil 6 by the alternating current application device 8, and an oscilloscope 28 was connected to the secondary coil 7. The time change of the voltage generated at both ends of the secondary coil 7 was observed with an oscilloscope 28, and the change in waveform was caught before and after the molten iron 33 in the converter reached the detection coil 4 embedded position. The phase difference between the peak value of the secondary coil signal, the phase of the secondary coil signal, and the phase of the AC voltage applied to the primary coil was observed. In FIG. 2B, the horizontal axis is time (based on the phase of the alternating current application device), and the vertical axis is the voltage across the secondary coil. The waveform 37 before reaching the molten iron is shown by a solid line, and the waveform 38 after reaching the molten iron is shown by a broken line. As shown in FIG. 2 (B), as the molten iron arrived, the waveform observed in the secondary coil showed a sharp change in the peak value 51 and a change 52 in the phase value. It is presumed that the induced electromotive force generated in the secondary coil 7 is changed by the appearance of the conductive molten iron 33 in the alternating current magnetic field 35 generated by the detection coil 4 and the flow of the induced current 36 in the molten iron 33 . Therefore, the detection time of the molten iron or the change by considering either or both of the peak value and the phase value of the secondary coil signal is detected by the detection device 9 by signal processing using a lock-in amplifier or the like. The depth of the molten metal can be detected.

Regarding the detection operation principle of the present invention, next, based on FIG. 3, using the detection coil 4 having one conductive coil 5, the AC current application device 8 is connected to the conductive coil 5 to apply an alternating current, and the detection A method of detecting a change in impedance of the coil 4 (conductive coil 5) will be described as an example.
When an alternating current is applied to the detection coil 4 (one conductive coil 5) by the alternating current application device 8, an alternating magnetic field 35 is generated in the detection coil 4. If a conductive substance is present within the range of the AC magnetic field 35 formed by the detection coil 4, the induced current 36 flows in the conductive substance due to the AC magnetic field, and as a result, the impedance of the detection coil 4 Changes. Therefore, by detecting the change in impedance of the detection coil 4 while applying an alternating current to the detection coil 4, it is possible to detect whether a conductive substance is present within the range of the AC magnetic field 35 of the detection coil 4. It becomes possible. In the present invention, in the discharge path 17 of the refining vessel (converter 1), the material of the portion of the furnace wall in contact with the furnace inner surface 16 is replaced with the molten slag 34 (low electrical conductivity) by the molten iron 33 (high electrical conductivity). The timing can be detected as a change in impedance of the detection coil 4. When a constant current type alternating current application device is used as the alternating current application device 8, the change in the voltage (voltage between the wiring 27a and the wiring 27c) at both ends of the detection coil can be detected as a change in impedance. In addition, when a constant voltage type alternating current application device is used, a change in the current flowing through the detection coil 4 (the current flowing through the wiring 27b) can be detected as a change in impedance.

  In many cases, a refractory having a relatively high electric conductivity such as magnesia carbon is usually applied to the refractory 12 used in a refining vessel such as the converter 1, so that the alternating magnetic field formed by the detection coil 4 of the present invention An induced current is also formed in the surrounding refractory by 35. On the other hand, if there is no change in the electrical conductivity and the like of the surrounding conductor, an induced electromotive force or impedance is generated in the detection coil 4 stably and with less change. In addition, temperature drift of the peak value and phase of induced electromotive force may be observed gradually due to temperature change of refractory around detection coil, etc., but the time change due to temperature drift is the arrival of molten iron Since it is slow compared to the time change caused by the above, it is easy to cancel the influence by the usual background removal circuit.

  FIG. 4 shows an example of plotting the time change of the peak value among the detection signals obtained in the example operation. The horizontal axis is the elapsed time, and the vertical axis is the peak value. As shown in this observation result, even when the same frequency and current are applied to the primary coil, it can be obtained as the induced electromotive force of the secondary coil under the influence of the electrical conductivity of the refractory and the attached metal during actual measurement. While the signal value differs, the change in signal (the above-mentioned temperature drift) due to the change in temperature and the change in the electrical resistance of the coil and surrounding conductors appears, but molten iron with high electrical conductivity passes over the coil Because a sharp peak occurs in the signal, the background removal circuit cancels the effect of temperature drift etc., and detects the arrival time of molten iron with high accuracy by setting the threshold for the rate of change of the signal. be able to.

  As described above, in the conventional method of electromagnetically detecting a phenomenon in which the effluent from the tapping hole changes from molten iron to molten slag, it is known that a detection delay actually exists, which restricts the use There is. In the case of slag detection at the tapping hole as generally shown in Patent Document 5 or determination of the end of ladle slag in continuous casting, the slag mixed in the tapping steel flow or the injection flow is initially a flow of It is known that it is mixed little by little at the center position and slag appears on the surface of the flow after the delay time has elapsed from the start of slag mixing. Since the initial condition is to detect the change in impedance when slag starts to flow into the nozzle filled with molten iron, the threshold is set under the condition where slag starts to flow little by little from the central part where the sensitivity of the detection coil is the worst. In the case where the threshold value is set to such an extent that there is no false detection, it is detected in a state where the interior of the nozzle is almost full of slag. On the other hand, in the case of molten iron detection in the tilting displacement targeted in the present invention, when the molten iron reaches the detection position in the furnace, the reached molten iron moves along the furnace inner surface of the furnace wall. Since a threshold is set for the phenomenon that molten iron with high electrical conductivity passes near the detection coil against the inflow of slag, which is a non-electrical conductor, a large signal change occurs even for the passage of a small amount of molten iron There is a structural advantage that it can be detected and the signal can be easily detected before the start of a large amount of molten iron at the time of discharge.

  Therefore, based on the above apparatus and principle, when the molten iron reaches the detection position at the top of the coil when the slag is discharged when the electric conductivity is significantly smaller than the molten iron, the signal value changes rapidly without time delay. It can be detected as arrival timing. As a result, the detection coil 4 is installed immediately before the discharge port (furnace port 2) in the discharge path 17, and control such as stopping tilting at the timing when the molten iron 33 reaches the detection position 18 above the installed coil By carrying out the above, the displacement can be carried out at a tilt angle in which the outflow of the molten iron 33 to the slag pan 3 is suppressed.

  In the present invention, as shown in FIG. 1B, it is preferable that a plurality of detection coils 4 be provided in the discharge path. This makes it possible to shorten the displacement time and greatly contributes to the improvement of productivity. FIG. 1B shows a diagram in which two detection coils 4 are provided in the tilting direction, which is an example of a desirable apparatus. At the time of slag discharge, the molten iron existing region moves in the direction of the furnace port 2 as the tilt angle is increased. A plurality of detection coils 4 are installed in the moving direction. The detection coil 4 on the side far from the furnace opening 2 is referred to as a first detection coil 4A, and the detection coil 4 on the side close to the furnace opening 2 is referred to as a second detection coil 4B. Thereby, the timing at which the molten iron 33 advancing toward the furnace port 2 reaches the detection position 18 of each detection coil 4 can be grasped individually. As an example of utilization of the effect, discharge is carried out at a high tilting speed until the molten iron reaches the detection position 18 of the first detection coil 4A from the tilting start, and the molten iron reaches the first detection coil 4A position After that, it decreases the tilting speed. Then, when the molten iron reaches the detection position of the second detection coil 4B, an operation such as stopping tilting can be performed. Therefore, it is possible to implement high-speed and high-yield tilt displacement by performing tilt displacement operation using the apparatus described above.

  Assuming that the implementation to the converter 1 which carries out molten iron refining of about 300 t / ch and is lined with magnesia carbon as the refractory 12, the conductive coil 5 which constitutes the detection coil 4 is heated together with the surrounding refractory. Therefore, the material of the coil is preferably a heat-resistant metal and a material having good processability as the coil, and examples of suitable materials include insulating-coated molybdenum of about 1 mmφ. Further, the magnetic field generated by the conductive coil 5 to which the alternating current is applied is proportional to the product of the applied current and the number of turns. If the size (diameter) of the coil is large, there is an adverse effect such as a decrease in magnetic flux density, so a coil with a diameter of more than 700 mm is not desirable. It is difficult to make. In addition, while the magnetic flux becomes strong when the applied current is high, the life of the coil is decreased due to heat generation, and so it is not desirable to apply a current exceeding 10 A. Good design can be achieved by increasing (A) x turn (-). Further, since the secondary coil 7 can increase the number of turns to enhance the voltage sensitivity of the induced electromotive force, designing with the same size and number of turns as the primary coil 6 is acceptable.

  Therefore, the detection coil and the wiring installed according to the present invention may be made of any material that can apply current and measure voltage at the temperature transmitted to the coil at the time of molten iron refining, so high melting point (molybdenum 2903 ° C) metal and tungsten (3653 ° C) are inexpensive and suitable.

  It is possible to cope with maintenance such as coil deformation and mechanical disconnection by carrying out at the time of off-line furnace repair if the refining container is a pot type. On the other hand, in the case of using a smelting vessel having a high operation rate as in the converter 1, repair and replacement work from the inner wall of the refractory is not desirable because it greatly deteriorates the productivity. In addition, the inside of the converter furnace in operation is at a high temperature, and the repair work performed from the inside of the furnace is difficult. Furthermore, in the case of a refining container or a large converter, the thickness of the wear brick 40 is about 800 mm immediately after building the wear brick 40 in the furnace as shown in FIG. In the case, wear progresses and the thickness of the wear brick 40 decreases to about 200 mm. The detection coil 4 of the present invention is preferably placed as close as possible to the furnace inner surface 16 in order to enhance the detection sensitivity of molten iron arrival, and is preferably provided within 500 mm from the furnace inner surface 16 as described above. If the buried position of the detection coil 4 in the wear brick 40 is fixed, the brick needs to be installed at a position where it will not be melted away (at a deep position from the furnace inner surface 16) even when wear progresses. Sufficient detection accuracy can not be obtained when the thickness is thick.

  On the other hand, in the present invention, the above-mentioned problem can be solved by using a method in which the detection coil 4 embedded in the furnace wall refractory is replaceably provided from the outside of the iron shell 42. That is, the detection coil 4 is accommodated in the coil exchange unit 22, and the coil exchange unit 22 is detachably mounted in the furnace wall 11 of the refining vessel from the outside of the refining vessel. As an example, a form in which coil exchange can be performed by the coil exchange unit 22 of the sleeve exchange system from the side of the iron skin 42 is shown as a reference drawing in FIGS. At the installation position of the detection coil 4, holes 21 for installation of the detection coil are provided in the iron skin 42, the permanent brick 41, and the wear brick 40 respectively. The coil exchange unit 22 having the detection coil 4 is inserted into the hole 21 from the outside of the iron shell 42 and installed. As shown in FIG. 6B, the coil exchange unit 22 has the outer periphery as a sleeve brick 23, the detection coil 4 is embedded inside, and the inside of the sleeve brick 23 is filled with, for example, magnesia filler 24. The position (the length from the iron skin 42 side) at which the detection coil 4 is installed can be changed according to the remaining thickness of the wear brick 40 at that time. Thereby, it becomes possible to maintain the distance between detection coil 4 and furnace inner surface 16 in the optimal range in response to the remaining thickness of wear brick 40 becoming successively thinner.

  When installing the coil exchange unit 22 in the furnace wall, the coil exchange unit 22 is inserted by passing the hole 21 of the iron shell 42 (FIG. 5), and the space between the coil exchange unit and the hole is magnesian Fill with a mixture of powder and water glass. The detachable exchange unit 25 at the bottom of the coil exchange unit 22 is fixed to the iron shell 42. Wiring 27 between the alternating current application device 8 and the detection device 9 is wired as an auto joint wire 29 up to the vicinity of the detection coil installation position. The auto joint wire 29 means a wire for easily connecting to the detector by a coupler method or the like when the replacement unit is inserted. In the terminal box 26 of the attachment / detachment exchange unit 25, the wire 27 is connected between the detection coil 4 and the alternating current application device 8 and the detection device 9.

  In order to verify the effect of the present invention, the tilting displacement method was implemented as a tilting type refinement device to which the present invention was applied as the upper bottom blowing converter of 300 t scale. The outline and results of the double slag blowing operation experiment using this converter are shown. The installation position of the detection coil 4 is, as shown in FIG. 1B, in the discharge path 17, 500 mm from the tip of the furnace lower end 19 (second detection coil 4B) and 1500 mm It was set as two places of 1 detection coil 4A). Insulating coils (20 turns) with a diameter of 60 mm and a diameter of 0.5 mm are respectively installed at a depth of 70 mm from the furnace inner surface 16 of the wear brick with the primary coil 6 and the secondary coil 7 as concentric axes. The constant current of 1 Hz (effective value) at 300 Hz and 1 A (effective value) is supplied by the alternating current application device 8, while the peak voltage (effective value) of the voltage generated in the secondary coil 7 is monitored by the detecting device 9 Carried out. When the peak voltage detected by the detection device 9 exceeded a preset threshold value, it was recognized that the molten iron reached the detection position.

The component (mass%) of the initial molten iron is 4.0 [C] -0.6 [Si] -0.08 [Mn] -0.15 [P] -0.005 [S] and the initial temperature of the molten iron is At 1300 to 1350 ° C., 9 t of quick lime was added before the first blowing and the first blowing (dephosphorization refining) was carried out for about 6 minutes at an acid feed rate of 40,000 Nm ³ / h. Thereafter, tilting displacement was carried out to discharge the dephosphorized slag. After exhausting is complete, the furnace body is rotated forward to add 5 t of a refining agent mixed with quick lime and converter slag mixed with a target of basicity 2.5, and the second blowing (decarburizing refining) at 70000 Nm ³ / h Then, steel was tapped at blowoff [C] 0.04-0.07%, 1635-1650 ° C. The blow stop [P] was evaluated, and the lower the blow stop [P], the higher the displacement rate in the tilting displacement and the less the rephosphorization phenomenon in the decarburization refining was evaluated. The slag and the base metal discharged to the slag pan in the tilting displacement of dephosphorized slag were crushed and magnetically separated, and the hot metal loss was evaluated from the weighing value of the ground iron.

  In the comparative example which does not use the detection of the present invention, the tilting speed was 3 ° / sec, and when the hot metal outflow was visually observed, the tilting was stopped, and the slag discharging was continued while stopping. In any of this comparative example and Examples 1 to 3 described later, the tilting displacement was finished and the converter was normally rotated when the discharge of the slag was not recognized.

  In Example 1, it was confirmed that the molten iron 33 reached the detection position 18 by performing tilting displacement with the tilting speed set to 3 ° / sec and monitoring only the signal of the second detection coil 4B 500 mm from the tip. At that time, the tilting was stopped and the patient was discharged.

  In Example 2, the tilting speed is high-speed tilting at 8 ° / sec until the molten iron 33 is detected by the monitor signal of the first detection coil 4A 1500 mm from the tip, and the backward tilting speed of detection is 3 ° It switched to 1 / second, and when the monitor signal of the 2nd detection coil 4B of a 500-mm position detected a molten iron, tilting was stopped and drainage was performed.

  Furthermore, in Example 3, until the molten iron is detected by the monitor signal of the first detection coil 4A of 1500 mm from the tip, the tilting speed is high-speed tilting at 8 ° / sec, and the backward tilting speed of detection is 1 ° / sec. By switching to low speed tilting and stopping the tilting when the monitor signal of the second detection coil 4B at the 500 mm position detects molten iron and performing displacement, it aims at a higher yield than in Example 2. is there.

  The experimental results obtained by the above experiment are shown in Table 1. Here, the metal loss is the iron loss that was discharged by tilting displacement after the first blowing (dephosphorization refining) was calculated and evaluated from the weighed value of the recovered metal in the slag pan, and at the time of the second blowing It is the value excluding the iron loss discharged at the time of iron content oxidation and the 2nd exhaustion. The blow stop [P] is a value obtained by analyzing the sample collected by sublance after the second blow (decarburization and refining) by the OES method (Kantback method).

  The definition of displacement time (seconds) here is the time from the start of tilting to the completion of displacement and switching of the status to normal rotation mode after stopping the first blowing and raising the upper blowing lance. Is defined in. Therefore, during this discharge time, the lance rise time after the first blowing stop, the tilt standby time until excessive slag forming sedation at the furnace opening, the lance from the completion of the tilt discharge to the normal rotation, and the second blowing start It is the value which excluded the non-blowing time until descent, and compared strictly the tilting displacement time shortening effect which is one of the effects of the present invention.

  As a result of the experiment, in all of the comparative examples and Examples 1 to 3, the blow stop [P] satisfied all 0.02% or less of the target value, and the dephosphorization slag was able to sufficiently discharge the dephosphorized slag by tilting displacement. Was recognized.

  Under the basic conditions (comparative example), the metal loss after the first blowing was 2.7 t / ch (yield loss 0.9%). On the other hand, the yield loss can be suppressed to 0.3% or less in Examples 1 and 2 and it can be confirmed that the effect of the high yield in the tilting displacement operation is remarkable by the implementation of the present invention. Furthermore, in the second embodiment having two detectors, high-speed tilting can be performed at a time when metal loss does not occur, so that the hot metal loss is at the same level as that of the first embodiment. Could be reduced by 30% or more, and it could be confirmed that it was possible to effectively improve the productivity. In addition, in Example 3 in which the final tilting speed was 1 ° / sec, the displacement time was equivalent to that of the comparative example and Example 1, but the metal loss could be significantly reduced as compared with Example 2. In the second embodiment, although the molten steel is detected by the second detection coil 4B and the tilting is stopped at the same time, the tilting speed before the tilting is 3 ° / sec. It was not possible to stop, and some molten iron flowed out of the furnace port 2. On the other hand, in Example 3, since the tilting speed before stopping the tilting was 1 ° / sec, it was possible to immediately stop the flow of molten iron after stopping the tilting and prevent the flow of molten iron from the furnace port 2 Presumed. Therefore, in an operation using an apparatus using a plurality of detection coils 4, an operation (Example 2) of shortening the displacement time while maintaining the metal loss at a low level can be performed because the inside of the furnace can be grasped more (Example 2) It could be confirmed that an operation (example 3) and the like can be carried out to suppress the above into a very low level.

  According to the present invention, in tilting displacement using a tilting type refining device such as a converter type refining vessel, an electric furnace, a pot type refining vessel, etc., it becomes possible to grasp the molten iron reaching condition to the discharge part without contact. Able to carry out high-yield scraping in a short time, reduce the cost of auxiliary agents (refining agents), reduce the amount of slag emissions accompanying it, and carry out operations with high industrial value such as productivity improvement etc. It is possible to carry out highly valuable operations.

1: Converter 2: furnace opening 3: slag pan 4: detection coil 5: conductive coil 6: primary coil 7: secondary coil 8: alternating current application device 9: detection device 10: cassette box 11: furnace wall 12: refractory 13: furnace bottom 14: furnace abdomen 15: furnace top 16: furnace inside surface 17: discharge route 18: detection position 19: furnace mouth lower end 20: furnace front 21: hole 22: coil exchange unit 23: sleeve brick 24: magnesia Filling material 25: Detachable exchange unit 26: Terminal box 27: Wiring 28: Oscilloscope 29: Auto joint wiring 33: Molten iron 34: Molten slag 35 Magnetic field 36 Induction current 37: Molten iron arrival 38: Molten iron arrival 40: Wear brick 41: Permanent brick 42: iron shell 51: peak value 52: change in phase value

Claims (5)

  In a tilting type refining apparatus capable of tilting a refining vessel, a path through which molten slag passes when discharging a molten slag in the refining vessel by tilting the refining vessel is referred to as a discharge path, and the refining vessel contacts the discharge path. A detection coil is provided in the furnace wall, the detection coil has one or a plurality of conductive coils, and an alternating current application device for applying an alternating current to the detection coil, and a change in induced electromotive force in the detection coil And a detection device for detecting a change in impedance of the detection coil.   The tilting type refinement device according to claim 1, wherein a plurality of the detection coils are provided in the discharge path.   The said detection coil is accommodated in a coil exchange unit, The said coil exchange unit is detachably mounted in the furnace wall of a refinement container from the outer side of a refinement container, It is characterized by the above-mentioned. Tilting type refining equipment.   It is the tilting displacement method using the tilting type refinement | purification apparatus of any one of Claim 1- Claim 3, Comprising: When tilting a refinement container and discharging the molten slag in a refinement container, it is said It detects that the molten metal has reached the detection coil installation position from the change in the induced electromotive force detected by the detection device or the impedance change, and reduces the tilting speed of the refining vessel or stops the tilting in response to the detection. Tilt displacement method characterized by having.   It is a tilting displacement method using the tilting type refinement device according to claim 2 or 3, and when the refinement container is tilted to discharge the molten slag in the refinement container, the induction detected by the detection device When the arrival of molten metal is detected by the detection device connected to the first detection coil by detecting that the molten metal has reached the detection coil installation position from the change in electromotive force or the change in impedance, the tilting speed of the refining vessel A second detection coil connected to the second detection coil to stop the tilting when the arrival of molten metal is detected.

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