JP4790502B2 - Blasting method for converter furnace mouth - Google Patents

Description

  The present invention relates to a technique for removing a bare metal adhering to an inner peripheral portion of a converter furnace opening by blowing off oxygen from a blow lance.

When blowing in a converter, it is known that molten iron blown off by an oxygen jet from a blow lance scatters and adheres to the inner periphery of the converter furnace as metal. And while the operation in a converter is repeated, the metal | bulb adhering to this converter furnace port grows gradually, and invites the diameter reduction of a furnace port. As a result, there is a risk that hot metal spills out of the converter furnace when hot metal is inserted. In addition, if the weight of the adhering metal increases and exceeds the support strength of the refractory bricks on the inner surface of the converter, the refractory bricks at the furnace port will peel off and fall into the furnace, leading to a reduction in converter life. become.
For example, as shown in FIG. 4A, when the blow lance 101 is inserted into the crucible type converter 100 and blown and refined, the hot metal blown off by the oxygen jet 102 is scattered and the inside of the furnace 100 of the converter 100 is scattered. In some cases, the base metal 105 adheres to the peripheral portion 103 and grows so as to form the base metal extending portion 106 in the center direction of the inner peripheral portion 103 of the furnace port. Here, when the mounting strength of the refractory brick 107 lined on the inner periphery 103 of the furnace port is high and can sufficiently support the weight of the bullion 105 and the bullion extension 106, If the weight of the protruding portion 106 causes a crack in the root portion of the extending portion 106 as shown in FIG. 4 (B), the bare metal extending portion 106 falls off due to its own weight and falls into the molten iron being refined. The operation of the furnace 100 is not hindered.
However, when the mounting strength of the refractory brick 107 is low, or when the bullion 105 and the bullion extending portion 106 grow more than the mounting strength of the refractory brick 107, the refractory brick 107 together with them as shown in FIG. In such a case, the iron wall of the converter 100 is exposed on the molten iron side as shown in FIG. 4 (D). Therefore, emergency repair is necessary, and the operation is stopped. There is a need to start repair work, there is a risk that the converter 100 may be damaged, and the converter is stopped to secure an emergency repair time, leading to a reduction in production.

For this reason, conventionally, the operation | work which removes the metal which adhered to the converter furnace port at the time of converter operation is performed.
As an example of conventional bullion removal work, bullion removal is performed by fusing bullion by an operator manually operating a blow lance and blowing oxygen to the bullion around the furnace port. However, this method has a problem that the working environment is very bad and a lot of time is required because it is a high-temperature work in the vicinity of the converter furnace opening. On the other hand, a method of swinging down a bar-shaped instrument using a heavy machine, causing the bar-shaped instrument to collide with a bullion attached to a converter furnace port, and removing the bullion by the impact force is also known, In addition to taking time to remove the bullion, there was a problem that the refractory bricks around the furnace mouth were easily damaged.

Therefore, as shown in the following Patent Documents 1 and 2, while inserting a blow lance having a structure capable of jetting oxygen in one direction into the converter furnace opening separately from the blow lance for blowing, There has been proposed a bullion cutting method for fusing the bullion. However, in these methods, the blow lance is rotated while spouting oxygen at a flow rate that can completely remove the attached metal, so that sufficient fusing can be achieved at the area around the converter furnace where there is a large amount of metal. Although the removal can be realized, there is a risk that the refractory bricks at the furnace entrance may be melted down by oxygen that has been excessively supplied at a portion where the amount of metal adhesion is small, leading to a reduction in converter life. Further, conventionally, since the start and end of the bullion cutting operation is performed depending on the operator's intuition, there is a problem that the operation time and the operation accuracy vary depending on the operator.
For this reason, as shown in Patent Document 3 below, a camera for photographing the periphery of the furnace port is disposed in the vicinity of the furnace port of the converter, and this camera monitors and grasps the amount of metal adhesion on the inner periphery of the furnace port, There has been provided a method of cutting a bare metal by using a blow lance configured to eject oxygen in one direction and controlling a rotation angle and an oxygen flow rate of the blow lance according to the amount of adhesion of the bare metal.
Moreover, as shown in the following Patent Document 4, as an example of a method for removing metal by blowing oxygen to the furnace port of a converter, there is a method for realizing metal cutting by blowing oxygen during steel output from the converter. It has been recommended.
Japanese Patent Laid-Open No. 5-179331 JP-A-5-223470 JP 2005-15849 A Japanese Patent Application No. 2-125809

In the bullion cutting method using the above-mentioned camera, it is necessary to check how the bullion is cut while checking the bullion cutting status with the camera, and each time you have to extend the bullion cutting time as necessary. In addition, there is a problem that when the bullion cutting time varies and the bullion cutting operation takes more time than necessary, the operation of the converter is affected.
For example, in the recent steel mill operation situation, from the viewpoint of improving production efficiency, after tilting the converter and discharging molten steel, when scrap is again put in and returned to the refining process, it is necessary to cut the metal. The time that can be allocated to the power plant is about a few minutes, so if you do not complete the bar cutting work within this few minutes and you cannot start the converter again, the converter operation may be affected. If the operation of the system is affected, there is a problem of adversely affecting the post-process. Therefore, there is a demand for a method that can complete the bullion cutting operation in a fixed time so as not to extend the bullion cutting time regardless of the growth state of the bullion.
Also, in the above-described method of blowing oxygen to the periphery of the furnace opening of the converter, if the oxygen is unnecessarily increased and more oxygen is sprayed than necessary, not only the metal but also the converter Since the refractory bricks constituting the inner wall will also be melted, it has been desired that the metal can be cut at an appropriate acid feed rate and working time.

  The present invention has been made in view of the above background, and finds a metal cutting method that does not cause variations in the fusing amount as much as possible even when the metal temperature is different, and does not hinder the operation of the converter. Is to provide.

The inventors of the present invention studied what conditions are influencing when injecting oxygen from the fusing lance to the inner peripheral side of the converter mouth and performing bullion cutting, and intensively studied the bullion cutting conditions. As a result, it was found that the fusing efficiency of the bullion changes depending on the surface temperature of the bullion before cutting the bullion. And based on this knowledge, as a result of earnestly researching on the correlation between the acid feed rate from the blow lance when performing the metal cutting operation, the metal surface temperature, and the amount of fusing, the present invention was reached.
(1) In the present invention, oxygen gas is blown onto the metal bar attached to the inner peripheral part of the converter furnace mouth using a fusing lance configured to be able to eject oxygen gas from the side surface of the tip part, In the ingot method of the converter furnace opening to remove by fusing, the allowable thickness of refractory adhesion lined in the converter is set in advance, and a control value lower than the allowable thickness of refractory adhesion is defined, A plurality of positions of the metal thickness in the circumferential direction of the inner periphery of the converter furnace mouth are grasped, and when at least one metal thickness at a plurality of grasp positions exceeds the control value, the oxygen gas is supplied by the fusing lance. spraying the bullion per to do bullion removed, when performing the該地gold removed, grasp the bullion blown amount according to bullion thickness in a specific range of blowing oxygen gas by lance blown, this bullion and fusing amount bullion surface defined from the average value of the measured temperature of the bullion The oxygen-flow-rate corresponding to the time, spraying previously grasped fusible bullion amount and該地gold surface temperature, the oxygen gas by the blowing lance and set based on the correlation between the oxygen-flow-rate in the bullion It is characterized by removing bullion.

( 2 ) The present invention grasps in advance the amount of metal that can be melted when oxygen gas is ejected from the fusing lance to the metal from the temperature of the metal and the acid feed rate, and at a specific acid feed rate. The relationship between the metal surface temperature and the fusing amount is determined as the relationship between the metal surface temperature and the fusing amount corresponding to a specific acid feed rate, and a plurality of the specific acid feed rates are defined, and the relationship for each specified acid feed rate. The bullion removal according to the amount of bullion fusing determined by the plurality of relationships according to the bullion temperature is performed.
( 3 ) The present invention relates to the relationship between the metal temperature and the metal fusing amount between the relationship defined by the one specific acid delivery rate and the relationship defined by the other specific acid delivery rate. Is present, the metal removal is performed by the fusing lance by setting the acid feed rate based on the relationship on the side having the larger amount of the metal fusing.
( 4 ) The present invention is characterized in that an injection angle when oxygen gas is ejected from the fusing lance to the metal is in the range of 30 ° to 150 ° in the circumferential direction of the fusing lance.

( 5 ) The present invention uses a profile measuring device to measure the amount of metal at a plurality of positions in the inner periphery of the furnace port at the time of tilting the converter, and measures the height direction of the inner periphery of the converter furnace port. Perform the three-dimensional measurement of the amount of bullion in the radial direction, grasp the amount of bullion in the inner circumference direction and the height direction of the furnace mouth, and if the thickness of at least one bullion exceeds the control value from these results, The bullion is removed by blowing oxygen gas onto the bullion with a fusing lance.
( 6 ) The present invention is based on the non-operating time of the converter between the heat and the next heat in carrying out the ingot method of the converter furnace inlet according to any one of (1) to ( 5 ). Set the bullion fusing time to the required amount of oxygen from the measured amount of molten bullion, set the acid feed rate of the lance for fusing from the required amount of oxygen and the amount of bullion Features.

According to the present invention, the amount of metal that can be melted by the fusing lance is measured in advance according to the surface temperature of the metal, or is grasped in advance by numerical calculation simulation, etc. Based on a control value that does not exceed the allowable thickness of the refractory at the converter furnace mouth, fusing with a fusing lance is performed according to the measured metal thickness or the metal thickness ascertained by calculation simulation, etc. There is an effect that the metal can be melted and removed without causing the refractory to fall off from the converter furnace part. In addition, it is possible to grasp the thickness of the bullion by measuring the thickness or calculating the thickness of the bullion and perform fusing work with a fusing lance when the control value is exceeded even at one location. It is possible to completely eliminate the drop-off, and there is an effect that it is possible to surely remove the molten metal from fusing.
Furthermore, if the metal at the converter furnace is removed, the metal does not get in the way of throwing in the scrap during the next heat blowing, so there will be no scrap charging trouble and the hot metal is converted into the converter. There is an effect that no charging trouble occurs even during the work of charging the battery.

  According to the present invention, based on grasping the fusing amount according to the metal temperature, grasping the metal fusing amount according to the metal thickness in a specific range, and setting the acid feed rate corresponding to this metal fusing amount. Since the metal is blown by blowing oxygen gas with the lance for fusing, the metal can be blown at an appropriate acid feed rate, and the metal in the inner periphery of the converter furnace is removed. The risk of excessively supplying oxygen is reduced, and the metal can be removed while reducing the risk of damaging the refractory material.

According to the present invention, the relationship between the base metal surface temperature and the fusing amount at a plurality of acid feeding rates is obtained, and the relationship between the base metal surface temperature and the fusing amount corresponding to the plurality of acid feeding rates is obtained. Since a suitable fusing is performed, a more appropriate acid feed rate and fusing conditions can be selected, and appropriate metal removal can be achieved without damaging the refractory material.
According to the present invention, if the injection angle of the oxygen gas from the fusing lance is in the range of 30 ° to 150 °, 1/4 of the bare metal at the converter furnace port is blown out. The bullion can be efficiently cut around a portion that needs to be cut in a short time by dividing into multiple times according to the state of the bullion deposition. Therefore, in the converter operation, the time for melting the metal can be shortened, and the metal can be melted without affecting the time for blowing in the converter.
According to the present invention, it is possible to measure three points using a profile measuring device and measure the amount of a bullion in a plurality of locations of a bullion. More reliable bullion removal.

  According to the present invention, in the converter operation that repeats the operation of blowing the converter and discharging the molten iron, it is possible to use the acid feed rate set from the non-operation time of the converter between the heat and the next heat. Desirable for efficient operation of furnace work.

The best mode of the method of the present invention will be described below, but the method of the present invention is not limited to the following best mode.
In FIG. 1, reference numeral 1 denotes a crucible type converter, and hot metal scattered during blowing is deposited on the inner peripheral portion of the furnace port 2 of the converter 1 shown upright in FIG. A state in which M is attached is shown. The converter 1 has a structure in which a large number of refractories (refractory bricks) 4 are lined on the inner surface of the iron skin 3. Reference numeral 5 denotes a fusing lance inserted into the converter furnace port 2 in a state where the converter 1 is upright. The blow lance 5 is provided with an elevating / rotating mechanism 6, and an elevating and rotating motion is performed by remote automatic control from a control panel 8 installed in the cab 7. A camera 9 is installed obliquely above the converter 1 so that the position of the front end side of the fusing lance 5 can be displayed on the monitor 10 of the control chamber 7.
In addition, a profile measuring device 11 is installed on the side facing the converter 1 in a state where the converter 1 is tilted and the furnace port 2 is turned sideways. FIG. 1 also shows a state in which the converter 1 is tilted and its furnace port 2 is turned sideways. However, when the converter 1 is tilted, the blow lance 5 is lifted upward from the position shown in FIG. Of course, it should not interfere with the furnace 1.

The profile measuring device 11 is a laser measuring device capable of multi-point observation as an example, and the metal M attached to the converter furnace port 2 is at an arbitrary position in the inner peripheral direction of the converter furnace port 2. And the thickness at an arbitrary position in the depth direction of the furnace port 2 (left and right direction when the converter 1 is tilted) can be grasped individually at multiple points. More specifically, since the laser measuring device measures unevenness of the surface shape of the object, the initial shape of the inner wall of the converter immediately after the replacement of the refractory material of the converter (the state that has not yet received hot metal) Can be applied as a device including a calculation unit that can calculate the thickness of a bare metal by comparing the measured value with a measurement result thereafter.
For example, in the case of a laser measuring device, the reflected wave that is reflected by irradiating a laser to the inner periphery of the converter furnace port 2 is measured, and the thickness of the metal M is grasped from the time difference. Thus, the thickness of the ingot at the inner periphery of the converter furnace port 2 can be grasped. The profile measuring device 11 used here is not limited to the laser measuring device, but may be an ultrasonic measuring device, a measuring device based on image analysis using a camera, or the like.
The image from the camera 9 is displayed on the monitor 10 of the cab 7, and the operator can monitor the adhesion state of the metal to the converter furnace port 2 with the monitor 10, and the fusing lance inserted into the upright converter 1. The tip position and posture of 5 can be monitored together.

As shown in FIG. 2 (A), the fusing lance 5 used in the present invention ejects high-pressure oxygen gas horizontally from a plurality of ejection ports 12 formed in parallel on the lower side surface of the cylindrical main end 5A. It has a structure to do. As shown in the cross-sectional structure of the lower portion of the blow lance shown in FIG. 2A, the opening angle α of the oxygen gas when the oxygen gas is ejected from the plurality of jets 12 is set to about 90 °. 5 is configured such that oxygen can be ejected to one side of the side surface of the tip portion.
If the front opening angle α is narrow, oxygen can be ejected at a pinpoint, but if the metal adhesion range is wide, it cannot be melted at a time, and it is necessary to change the position and blow in multiple times However, if the front opening angle α is too wide, there is a risk that the refractory will not be attached to the refractory, which may cause the refractory to melt. Accordingly, it is preferable to appropriately select the front opening angle α in the range of 30 ° to 150 °, and particularly preferably around 90 °.

  Since the blow lance 5 for fusing is inserted into a high-temperature furnace, it is preferable that the side walls have a water cooling structure. Further, it is preferable that the operation panel 8 can automatically control the height and rotation angle of the blow lance 5 and can also automatically control the flow rate of oxygen gas.

Below, the procedure of the converter furnace neck metal fusing method of this invention is demonstrated.
The converter operation is generally performed by refining pig iron in the converter using a blown blown blown blown (not shown) separately provided near the converter 1 and tilting the converter 1 after the refining is completed. After the molten steel is discharged, and then scraps and the like are added, the hot metal is poured again and refining is performed repeatedly. In this converter operation, the hot metal spatters with the operation of blowing oxygen gas to the hot metal while repeatedly blowing with the blow lance for blow blowing, and as the metal M on the inner periphery of the converter furnace port 2 It gradually adheres.
In the present invention, in this converter operation, during the tilting, the profile measuring device 11 sequentially measures and monitors the amount of metal in the inner periphery of the converter furnace port 2 and monitors the amount of metal in accordance with the amount of metal M attached. Stipulates the allowable thickness of the refractory corresponding to a value slightly lower than the limit value of the support strength of the refractory 4, and if the allowable thickness of the refractory exceeds the specified control value due to the adhesion of the base metal M M is blown out.

Prior to the fusing operation of the metal in accordance with the method of the present invention, the thickness of the metal that can be melted by the fusing lance 5 and the thickness of the metal that can be melted according to the level of the metal temperature are experimentally measured in advance, and the correlation between them is measured. Keep track of measurements.
Depending on the shape of the lance for fusing (width, height, spread angle of the discharge part), the metal wall area (“effective melting area”) of the furnace wall that can be fused differs, and this “effective melting area” is obtained in advance by fusing experiments. If the actual fusing amount is divided by “effective melt cross-sectional area” and “ingot specific gravity (here, iron specific gravity of 7 is used)”, “ingot thickness” can be calculated.
Therefore, in actuality, the measured “metal thickness” is multiplied by “effective melting cross-sectional area” and “bulk specific gravity (here, iron specific gravity is 7)” to “cut the metal (per effective molten cross-sectional area)” “Amount” is calculated, and “Oxidation rate” is determined from “Base metal temperature” and “Base metal fusing time” using the relationship shown in FIG.

FIG. 3 shows an example of the measured values. When the divergence angle is 90 ° from the side surface of the front end of the fusing lance 5 and the acid feed rate is 10000 Nm ³ / hr, and when the acid feed rate is 15000 Nm ³ / hr, Measure the fusing amount of the metal M adhering to the inner periphery of the converter furnace port 2 by experiment for each metal temperature, and grasp the metal fusing amount for three ways when the acid feed rate is 20000 Nm ³ / hr And keep track of their correlation.
FIG. 3 shows data when the “bulb fusing time” is 2 minutes. For example, even if the fusing time changes, the fusing amount is considered to be directly proportional to the amount of acid fed (acid feeding speed and fusing time). Therefore, the relationship of FIG. 3 can be applied as it is. In FIG. 3, the front opening angle α of the fusing lance is 90 °, and the distance between the fusing lance and the metal surface of the converter furnace wall is 2.5 m, “effective fusing area” (90 ° irradiation range) = This is data in the case of 2.75 m ² (= 2.5 × 2 × π × 90 ÷ 360).

Here, the main component of the bare metal M adhering to the converter furnace port 2 is generally Fe, FeO, Fe ₂ O ₃ and other CaO when ordinary blowing is performed in the converter 2. Consists of mixed components.
Further, there is a relationship of Fe + (1/2) O ₂ → FeO + 64 kcal and Fe + (3/2) O ₂ → Fe ₂ O ₃ +190.7 kcal, both of which are ingots when oxygen gas is blown by the fusing lance 5 Heat is generated at the oxygen sprayed part of M. The ingot M is melted and melted by the generated heat, dropped into the converter 1, and the ingot M can be removed from the inner periphery of the furnace port 2.

The inventors of the present invention have found that when the oxygen gas is blown and blown to the metal M by the fusing lance 5, the amount of fusing differs depending on the surface temperature of the metal M even under the same oxygen blowing rate and time. As a result of testing as shown in FIG. 3, the amount of fusing of the ingot M increases as the acid feed rate from the fusing lance 5 to the ingot M increases, but the relationship of the increase is not uniform. It was possible to grasp that it fluctuated by being greatly influenced by the surface temperature of the metal M during acid feeding.
As a result, the correlation with the metal surface temperature for the same acid feed rate is as follows. As the metal surface temperature is improved to 600 ° C., 650 ° C., 700 ° C., and 750 ° C. The result that (t) increases can be obtained, and the relationship can be displayed by three correlation curves (correlation formula: correlation) corresponding to the three acid delivery rates shown in FIG. The result was obtained. Moreover, the correlation curve of previous shifts the oxygen-flow-rate ^{10000Nm 3 / hr, 15000Nm 3 /} hr, in a direction bullion blowing amount is increased with increasing the 20000 nm ³ / hr, oxygen-flow-rate for their correlation It has been found that the amount of fusing increases as the value increases.

In the present invention, the knowledge as described above is utilized, and the fusing operation of the metal M is incorporated into the actual converter operation after grasping the relationship between the acid feed rate and the metal melting amount.
More specifically, in the relationship shown in FIG. 3, the amount of metal that can be melted at the inner circumference 90 ° of the converter furnace port 2 to which the fusing lance 5 blows oxygen gas is, in other words, the thickness of the metal that can be melted. You can also see the thickness of this bullion.
Further, a refractory 4 such as a refractory brick is lined inside the converter 1, and these refractories 4 are provided in the converter 1 with a desired strength. Here, for example, as the supporting strength of the refractory, when converted from the weight of the above-described metal M, Fe, FeO, Fe ₂ O ₃ and other components are 12%, 18%, 17%, 53%. As a ratio, refractory peeling does not occur up to a bare metal thickness of about 500 mm as the support strength of the refractory, but if the thickness of the bullion exceeds 500 mm, there is a risk of refractory peeling. In this case, the management value of the metal thickness is set to 100 mm or more and 400 mm or less (for example, 20% to 80% of the maximum safe metal thickness (about 500 mm)), and this management value is input to the control device 8 to Perform gold thickness management.

  As the converter 1 is operated, when the thickness of the metal M is observed one by one at the time of tilting by the profile measuring device 11 described above, the control device 8 monitors which range of this control value is used, and multipoint measurement is performed. While the thickness of the metal M is monitored, if the metal thickness exceeds 400 mm even at one point (one measurement position), the metal M is melted by the fusing lance 5 after tilting after the end of blowing. I do. Therefore, when the metal thickness M is in the range of 100 to 400 mm in all regions by multi-point measurement by the profile measuring device 11, the converter 1 is corrected as it is without melting the metal M after tilting. Repeat the normal converter operation of standing and blowing again.

In the multipoint measurement by the profile measuring device 11, when the thickness of the bare metal exceeds the management value 400mm of the bare metal M, the following bare metal fusing operation is performed.
For this purpose, the surface temperature of the bullion M is defined from the average value of the measured temperatures of the bullion M measured by the profile measuring device 11, and the load of the bullion M measured by the profile measuring device 11 is calculated to protect the refractory. The controller calculates and estimates the amount of fusing required to perform the process, and applies the relationship to the correlation curve previously determined by experiment shown in FIG. 8, the control device 8 determines the acid feed rate from the fusing lance 5 and performs the fusing operation.
As shown in FIG. 1, the fusing operation is actually performed after the converter 1 is upright, and then the fusing lance 5 is inserted into the inner periphery of the converter furnace port 2, and is approximately 90 from the jet 12 of the fusing lance 5. It is only necessary to blow the metal gas M in the corresponding area by blowing an oxygen gas having a width and drop it to the bottom of the converter 1. The dropped metal M can be confused with other input materials as it is in the next step of blowing after fusing.

Further, the profile measuring device 11 measures the thickness of the ingot around the inner periphery of the converter furnace port 2 and successively determines whether the ingot thickness M is within the control value of 100 to 400 mm. Understand management. Thus, the fusing operation can be performed while grasping which region of the metal M is growing significantly.
As an example, when the metal melting time is 2 minutes, the metal surface temperature is 700 ° C., and the metal melting required amount is 3.5 t according to the scale of the converter 1, the acid feeding rate is 20000 Nm ³ / It can be seen that if h is selected, a necessary and sufficient amount of the metal M can be fused.
Incidentally, 10000 Nm ³ / ^hr of oxygen-flow-rate of the blown lance 5 as shown in FIG. 3, 15000 nm 3 / hr, when 20000 nm ³ / hr capable of changing three stages only, oxygen-flow of 15000 nm ³ / hr illustrated in Figure 3 The metal fusing amount may be set to an intermediate value between the velocity correlation curve and the acid feeding velocity correlation curve of 20000 Nm ³ / hr. For example, in the case of a metal surface fusing amount of 3 t at a metal surface temperature of 700 ° C., it is an intermediate value between the two correlation curves. In such a case, an acid feed rate of 20000 Nm ³ / hr is taken into account in the margin of fusing amount. It is only necessary to melt the bullion by applying the correlation curve.

However, if the base metal M is melted at an excessive acid feed rate, oxygen that is available to the inner peripheral surface of the converter furnace port 2 is blown to the inner peripheral surface of the converter furnace port 2 more than removing the base metal M adhering to the inside of the converter furnace port 2. As a result, the risk of damaging the refractory in the inner periphery of the converter furnace port 2 is increased. At this point, if the acid feed rate is selected so as to follow the correlation curve of the next higher level in the intermediate value of the correlation curve shown in FIG. 3, damage to the refractory in the inner periphery of the converter furnace port 2 will also occur. It can be suppressed as low as possible. Of course, when the target fusing condition is located between the correlation curves shown adjacent to FIG. 3, a weighted average may be taken and the acid feed rate may be finely adjusted based on the average value. As a result, a necessary amount of the metal M can be melted at a more accurate acid feed rate.
Therefore, by carrying out the fusing method of the present invention, it is possible to obtain a reliable metal fusing effect while reducing the risk of refractory damage.

  By the way, the relationship shown in FIG. 3 is an example when the fusing time is 2 minutes, but it is not always necessary to complete the metal fusing time in 2 minutes, and 2 minutes is extremely related to the non-operation time of the converter. Consider an example of a short case. In other words, the refining schedule of the converter is fixed, and from the balance with the production volume, if there is a margin, the non-operation time will naturally be longer than 2 minutes, so in that case the metal fusing time will be longer than 2 minutes Can be extended in time. However, as mentioned above, increasing the acid feed rate by increasing the metal cutting time may increase the damage to the refractory. On the other hand, there is time to spare and it takes too much time to cut the metal. Since the metal temperature may decrease and the efficiency may worsen, an appropriate time may be selected.

  Further, as described above, the image of the converter furnace port 2 is displayed on the monitor 10, and the operator monitors the status of the metal M displayed in this image and the status of the inner peripheral surface of the converter furnace port 2. While doing this, it is possible to perform the metal fusing work. Accordingly, for example, one ingot M having a thickness exceeding the control value of 400 mm is generated in the entire periphery of the converter furnace port 2 and, in the 90 ° range including the occurrence location, the ingot M other than the generated portion Is much thinner, for example, when it is so thin that the control value is closer to 100 mm than the control value of 400 mm, there is a possibility of damaging the refractory on the inner peripheral surface of the converter furnace port 2 by excessive oxygen blowing, In that case, it is preferable to stop the fusing as soon as possible after confirming the fusing of the thick metal M part. Thus, by fusing while displaying and monitoring the image of the converter furnace port 2 on the monitor 10, the fusing operation can be performed while preventing damage to the converter furnace port part.

In the fusing operation, it is preferable that the metal M is blown by blowing oxygen with a large amount of metal adhesion, with the center of the spread angle of the fusing lance aligned with the thickest part of the metal. Moreover, it is desirable to always leave a predetermined amount of metal M in the converter furnace port 2. The thickness of the metal M is about 100 to 200 mm, for example. For this reason, according to this invention, the metal M adhering to the inside of the furnace port can be blown out without melting the refractory in the inner periphery of the furnace port 2. The thickness of the metal M can be automatically confirmed by a monitor image from the camera 9, for example.
As described above, in the present invention, it is desirable to remove the bare metal M in the portion where the adhesion amount of the bare metal is large while controlling the oxygen flow rate of the blow lance 5. In addition, when the spread of the metal M to be melted is larger than the spread angle of the fusing lance, it is desirable to perform the fusing while reciprocating the fusing lance left and right around a portion where the amount of metal adhesion is large. In addition, it is preferable that the acid feeding speed is changed depending on the height of the blow lance 5. That is, it is preferable to reduce the oxygen flow rate when the outlet 11 of the blow lance 5 is in the vicinity of the steel outlet of the converter furnace 2 to prevent the refractory brick near the steel outlet from being melted.

By the way, in this embodiment, as the control value for fusing the metal M, the metal thickness 500 mm is set to 80% of the support metal limit value, which is set to 400 mm, but these values are the structure of the converter 1 and the refractory. Of course, it is necessary to set appropriately according to the structure and scale of the converter to be applied. Therefore, depending on the converter, a lower metal thickness can be regarded as the support limit value, and 80% of the limit value or a value lower than that can be regarded as the upper limit of the control value, which can be used as a guide for starting fusing.
Moreover, in this Embodiment, although the amount of adhesion | attachment of the bullion M was grasped | ascertained by measuring with a profile measuring apparatus, when grasping | ascertaining the adhesion amount and adhesion | attachment state of the bullion M, the bullion M was calculated by numerical simulation It is also possible to predict and grasp the amount of adhesion and the state of adhesion.
Furthermore, if the metal M at the converter furnace port is removed as described above, the metal does not get in the way of throwing in the scrap when charging the next converter operation. In addition, there is an effect that hot metal charging trouble does not occur even when the hot metal is charged into the converter 1 and the converter operation is performed. For example, if the converter furnace port 2 is partially blocked by the metal M during the scrap charging operation, the scrap may come into contact with the metal M and interfere with the charging operation. Further, when charging for the start of the converter operation, the metal M protruding from the converter furnace port 2 may become an obstacle and the hot metal may spill outside.

During the converter operation, the relationship between the amount of molten metal attached to the converter furnace mouth, the acid feed rate from the fusing lance, and the surface temperature of the metal was tested.
Bullion adhering to the converter furnace outlet to part collected results of component _{analysis, Fe = 12%, FeO18%} , Fe 2 O 3 = 17%, were other ingredients 53% like CaO. As a fusing lance, a lance having a diameter of 30 cm, a length of 10 m, and 7 spouts with an inner diameter of 2 cm formed on the side surface of the tip portion at an equal interval in the circumferential direction at a range of 90 ° on the peripheral surface of the tip portion was used. 10000 Nm ³ / ^hr of oxygen-flow-rate of the blowing lance, 15000 nm 3 / hr, and adjusted to three levels of 20000 nm ³ / hr, temperature and blowing amount of the surface portion of the bare metal of the converter furnace port at each oxygen-flow-rate As a result of fusing work under the condition of fusing time of 2 minutes, the amount of metal that could be melted was measured.
The amount of the bare metal that could be melted was calculated and grasped from the difference between the average thickness of the bare metal by the profile measuring device before the start of melting and the thickness of the residual bare metal measured by the profile measuring device after the end of melting.

The above results are shown in FIG. Here, the time required for the operation of one heat is defined as 50 minutes, and since the operation time is normally about 48 minutes, the non-operation time of 2 minutes is generated, so the metal cutting time is defined as 2 minutes.
From the results shown in FIG. 3, the oxygen-flow-rate ^{10000Nm 3 / hr, 15000Nm 3 /} hr, bullion blown amount as it rises 20000 nm ³ / hr tends to increase in any of the bare metal surface temperature. In addition, the relationship between the metal fusing amount and the metal surface temperature increases geometrically as the metal temperature rises to 600 ° C., 650 ° C., 700 ° C., and 750 ° C. at the same acid feed rate. It became clear.
Therefore, if the relationship shown in FIG. 3 is grasped, for example, in the case of a metal surface temperature of 700 ° C. and a metal fusing required amount of 3.5 t, it is ensured by setting the acid feed rate of 20000 Nm ³ / hr from the relationship of FIG. It can be seen that the metal can be melted.

  In addition, after the blowing is completed in the operation of the converter and the molten steel is discharged, the metal temperature gradually decreases. The suitable acid feed rate from the fusing lance varies depending on the point at which the metal is blown from the time of the reduction. However, in the operation of the converter, it is not always possible to blow out the metal at the same temperature, and the time taken to melt the metal is not determined according to various conditions during operation. Choosing a suitable acid feed rate according to the temperature is a very effective method for fusing ingots. Even if metal fusing starts at any point after the molten steel is discharged, the ingots are melted at a suitable acid feed rate. be able to.

FIG. 1 is a configuration diagram for explaining an example of an implementation status of a method for fusing a metal bar according to the present invention, and is a configuration diagram showing an arrangement state of a converter, a fusing lance, and other equipment. 2A and 2B show a fusing lance used in the fusing method according to the present invention. FIG. 2A is a perspective view of a lower end portion of the fusing lance, and FIG. 2B is a partial cross-sectional view of the fusing lance. FIG. 3 is a graph showing the relationship between the amount of metal melt and the surface temperature of the metal when the acid feed rate of the fusing lance is changed in the converter. FIG. 4 shows the operation state of the conventional converter and the state of the metal, and FIG. 4 (A) is a cross-sectional view showing a state where the blowing lance is inserted into the converter and blown, FIG. 4 (B ) Is a cross-sectional view showing a state in which the metal has fallen from the furnace port portion of the converter, FIG. 4C is a cross-sectional view showing a state in which the refractory of the converter is peeled off together with the metal, and FIG. Sectional drawing which shows the state which the refractory of the converter fell in the converter with gold | metal | money.

Explanation of symbols

1 converter,
2 Converter furnace opening,
3 Iron skin,
4 refractories (refractory bricks),
5 Lance for fusing,
8 control device,
9 Camera,
10 monitor,
11 Profile measuring device,
12 spouts,

Claims (6)

A converter furnace port that blows and removes metal from the inner periphery of the converter furnace by blowing it using a fusing lance that can blow out oxygen gas from the side of the tip. In the bullion cutting method of
The allowable thickness of the refractory attached to the converter is set in advance, a control value lower than the allowable thickness of the refractory is defined, and the thickness of the metal in the circumferential direction of the inner periphery of the converter furnace is set. When performing multiple position grasping, and when the metal thickness of at least one location of the plurality of grasping positions exceeds the control value, when performing the metal removal by blowing oxygen gas to the metal with the fusing lance ,
When performing該地gold removed, grasp the bullion blown amount according to bullion thickness in a specific range of blowing oxygen gas by lance Blown, and the bullion blowing amount, the average value of the measured temperature of the bullion The oxygen feed rate corresponding to the metal surface temperature specified from the above is set based on the correlation between the meltable metal volume, the metal surface temperature, and the acid feed rate ascertained in advance. A method of blowing a bullion to the bullion to remove the bullion. The amount of metal that can be melted when oxygen gas is ejected from the fusing lance is preliminarily determined from the temperature of the metal and the acid feed rate, and the surface temperature of the metal and the amount of fusing at a specific acid feed rate. Is determined as a relationship between the metal surface temperature corresponding to a specific acid feed rate and the fusing amount, a plurality of the specific acid feed rates are defined, and a relationship for each specified acid feed rate is determined, 2. The method for fusing a bullion at a converter furnace port according to claim 1 , wherein the bullion is removed according to the amount of bulge fusing determined by the plurality of relationships.   When there is a relationship between the metal temperature and the metal fusing amount between the relationship defined by the one specific acid delivery rate and the relationship defined by the other specific acid delivery rate, 3. The method of fusing a bullion at a converter furnace mouth according to claim 2, wherein the bullion removal is performed by the fusing lance by setting the acid feed speed based on the relationship on the side having a larger amount of bullion fusing. 4. An injection angle when oxygen gas is jetted from the fusing lance to the metal is in a range of 30 [deg.] To 150 [deg.] In the circumferential direction of the fusing lance. Method of fusing ingots at the converter furnace.   Using a profile measuring device to measure the amount of metal at multiple positions in the inner periphery of the furnace port during tilting of the converter, the amount of metal in the height direction and radial direction of the inner periphery of the converter furnace port is measured. Three-dimensional measurement is performed to determine the amount of metal in the furnace port inner circumferential direction and height direction. From these results, when the thickness of at least one metal bar exceeds the control value, oxygen gas is supplied by the fusing lance. 5. The method of fusing a bullion in a converter furnace opening according to claim 1, wherein the bullion is removed by spraying on the bullion.   In carrying out the method for fusing the ingot of the converter furnace according to any one of claims 1 to 5, the ingot cutting time is set based on the non-operation time of the converter between the heat and the next heat, and measured. The amount of oxygen required is determined from the amount of molten metal that has been cut, and the metal is blown by setting the acid feed rate of the fusing lance from the amount of necessary oxygen and the amount of metal. A method for fusing metal in the converter furnace port according to the above.

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