JP2010156471A - Method of managing refractory body of molten iron container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely prevent leakage of molten iron from a molten iron container, manage a refractory body of the molten iron container according to the plan, and use the refractory body to the limit as much as possible. <P>SOLUTION: Before use of the molten metal container, a monitoring portion and an erosion factor are determined. Erosion quantity of the monitoring portion when unit quantity of the erosion factor is applied is calculated, and erosion quantity per charge of the monitoring portion is calculated. An end point determination criterion by the thickness of the refractory body is determined. During use of the molten iron container, when actually measured remaining thickness of the refractory body is smaller than estimated remaining thickness of the refractory body, repair is performed in accordance with the difference. When the actually measured remaining thickness of the refractory body is larger than the estimated remaining thickness of the refractory body, scheduled use frequency of the molten iron container is reexamined. When use frequency in next charge is larger than the scheduled use frequency, the molten iron container is repaired. When the use frequency in next charge is smaller than the scheduled use frequency, the molten iron container is used also for the next charge. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for managing a refractory in a molten iron container that manages the transition of the remaining thickness of the refractory provided in the molten iron container.

Conventionally, molten iron containers into which molten iron or molten steel is charged have been used in various places in steel factories. For example, although a molten iron container is used in a secondary smelting facility such as an LF apparatus, the refractory in the molten iron container will progress due to various factors during the secondary smelting treatment. It is very important to monitor the refractory condition and repair the refractory because the refractory erosion progresses by repeatedly using the molten iron container, which leads to leakage and steel leakage.
As described above, various techniques have been developed as techniques for monitoring or repairing the molten state of the molten iron container.

In the repair method for the molten metal lining container (molten iron container) of Patent Document 1, the remaining thickness of the lining refractory is calculated, the distribution of the remaining thickness in the lining container is automatically obtained, and the erosion rate of each part is calculated. After the automatic calculation, the amount of spray material supplied per hour, the supply pressure, the nozzle moving speed, the spray time, and the number of times of spraying are automatically repaired until the set remaining thickness corresponding to each melting rate is reached.
Moreover, in the refractory repair method of a chaotic vehicle of patent document 2, while setting a some division | segmentation zone on the refractory surface in a chaotic vehicle, the repair thickness condition in each division | segmentation zone is set, and the expected wear pattern of a refractory After receiving and operating, measure the actual wear pattern of the refractory using a profile meter, compare the actual wear pattern with the expected wear pattern, select the optimal repair pattern, and re-set the repair thickness condition based on this Set and automatically repair refractories based on this condition.

As described above, Patent Document 1 and Patent Document 2 are for repairing a refractory while obtaining a refractory condition such as a remaining thickness of the refractory. It is not a technique that considers the end point determination of whether it can be used until charging.
As a technique for determining the end point while taking into consideration the state of melting damage such as the remaining thickness of the refractory, there is one disclosed in Patent Document 3.
That is, in the management method of the nozzle-like refractory of Patent Document 3, the management part is measured at least once out of the maximum number of use R by the measuring element, and when the measured value exceeds the control value, the nozzle-like refractory is measured. It is judged that replacement is necessary, and if the control value is not exceeded, it is judged that continuous use is possible.
Japanese Patent Publication No. 6-48139 Japanese Patent No. 3687883 Japanese Patent Laid-Open No. 4-17610

In Patent Document 1 and Patent Document 2, refractories are repaired in consideration of the remaining thickness of the refractory, but when predicting the change in the remaining thickness of the refractory, the operation status and the characteristics of the erosion site and However, there is a problem that the remaining thickness of the refractory cannot be properly predicted depending on the operation status.
In Patent Document 3, although the end point is determined while taking into consideration the molten state such as the remaining thickness of the refractory, it is for the nozzle-like refractory. It is difficult to apply to refractories.

  The present invention has been made in view of the above-described problems, and can reliably prevent leakage of molten iron from the molten iron container, and can manage the refractory of the molten iron container in a planned manner, thereby making the refractory. It aims at providing the management method of the refractory of the molten iron container which can be used to the limit as much as possible.

The technical means of this invention exists in the point which manages the remaining thickness transition of the refractory provided in the molten iron container in the following procedure.
(1) Determine the monitoring site to be monitored before using the molten iron container.
(2) Determine the erosion factor that contributes to the erosion loss at the monitoring site.
(3) The unit factor erosion amount of the monitoring site when the unit amount of erosion factor is applied is determined.
(4) The average amount of the erosion factor imparted by one charge is determined, and the one-charge erosion amount per charge of the monitored portion is determined from the average amount and the unit factor erosion amount.
(5) The repair amount for increasing the refractory by 1 mm is obtained.
(6) Establish end point criteria based on the thickness of the refractory from the limit of use of the refractory.
(7) Estimate the remaining thickness of the refractory at the monitoring site based on the operation results of the erosion factor during use of the molten iron container.
(8) Measure the remaining thickness of the refractory during use of the molten iron container.
(9) The estimated remaining thickness of the refractory is compared with the actually measured remaining thickness of the refractory.
(10) When the remaining thickness of the measured refractory is smaller than the estimated remaining thickness of the refractory, the actual repair amount is determined based on the repair amount determined in (5) according to the difference, and repair is performed. The estimated number of times of use of the molten iron container is reviewed using the estimated remaining thickness and the one-charge erosion amount.
(11) When the actually measured remaining thickness of the refractory is larger than the estimated remaining thickness of the refractory, the estimated number of times of use of the molten iron container is reviewed using the estimated remaining thickness and the one-charge erosion amount.
(12) If the number of uses in the next charge is greater than the planned number of uses, the molten iron container is taken out for repair.
(13) When the number of uses in the next charge is smaller than the planned number of uses, the molten iron container is also used for the next charge, and the above (7) to (12) are repeated.
(14) However, if the remaining thickness of the refractory cannot be measured in (8) above, after reviewing the estimated number of times of use of the molten iron container using the estimated remaining thickness and 1 charge erosion amount, The above (7) to (12) are repeated.

  According to the present invention, leakage of molten iron from a molten iron container can be reliably prevented, and the refractory of the molten iron container can be managed systematically, and the refractory can be used as much as possible.

The management method of the refractory of the molten iron container of this invention is demonstrated.
Molten iron containers charged with hot metal and molten steel are used between blast furnaces and converters, used between converters and secondary refining, and used between secondary refining and continuous casting equipment. Used.
Thus, although a molten iron container is used in various places, whenever this molten iron container is used, the refractory provided in the molten iron container will be melted. If refractory erosion progresses, it will lead to leakage and steel leakage, so monitoring of the refractory erosion status, that is, refractory management (remaining thickness control) is very important.

The refractory management method for the molten iron container of the present invention will be described in detail.
In this invention, as shown in FIG. 1 and the following, the refractory of the molten iron container is managed according to procedures (1) to (13).
The procedure from (1) to (6) is a matter to be performed in advance before using the molten iron container, and the procedure from (7) to (14) is a matter to be performed while using the molten iron container.
(1) First, a site to be monitored (monitored site) is determined before using the molten iron container (procedure 1). Specifically, in determining the monitoring site, the measured value of the remaining thickness of the refractory when the molten iron container is repaired (sometimes referred to as the remaining thickness measured value), the remaining thickness measured value during operation, Refer to the operation details. In this way, due to changes in the remaining thickness of the refractory at the time of repair, the remaining thickness during operation, and the contents of the operation at that time, the risk of parts, leaks and steel leaks that are likely to cause repair of the refractory Select a part with.

FIG. 2 summarizes, for example, items that have become a factor (operation end-point limiting) for repairing a molten iron container in secondary refining in an LF apparatus. As shown in FIG. 2, 65% of the total molten iron containers have been repaired out due to the slag line melt damage (SL melt damage). It is the main factor. Therefore, in the molten iron container used for secondary refining, the slag line part is used as a monitoring site.
In the secondary refining process, the bottom of the molten iron container became the rate at which the operation end point was controlled by 5% of the total, which is much less affected than the slag line part. When using a molten iron container for processing), do not use the laying part as a monitoring site.

(2) A factor (melting factor) contributing to melting damage is determined at the monitoring site (procedure 2).
Specifically, the molten iron container has various monitoring parts as described above, but there is a correlation between the measured thickness of the refractory when the molten iron container is repaired at each monitoring part and the operation content. Among these, the one having a correlation is defined as a melting factor.
For example, when the monitoring site is a slag line part, analysis of the erosion factor having a strong correlation with the slag line part's erosion from the operation content, etc., the secondary refining process is performed using the LF device. It was found that the amount of energized electricity (integrated arc power) and the number of energizations were most correlated with the slag line melting. When monitoring the slag line portion, the energization power amount (integrated arc power amount) and the number of energization times are determined as the erosion factors.

FIG. 3A and FIG. 3B summarize the relationship between the measured value of the remaining thickness of the refractory in the slag line part and the operation content, focusing on the slag line part.
As shown in FIG. 3 (a), there is a strong correlation between the measured residual thickness value of the slag line portion and the energized power amount (integrated power amount), and as shown in FIG. 3 (b), the residual thickness measurement of the slag line portion. The correlation between the value and the number of uses of molten iron containers is weak. In this way, the correlation between various operation contents and the measured thickness of the refractory is obtained for one monitoring part, and what is considered to be a melting factor for the monitoring part is picked up depending on the strength of the correlation. .

  In addition to the slag line part, when the laying part is used as a monitoring part, the operation results show that there is a strong correlation between the residual thickness measurement value of the laying part and the number of injection treatments (number of times of blowing), the amount of blowing and the number of times of use. Therefore, the erosion factor of the laying part is selected from the number of times of blowing, the amount of blowing, and the number of times of use. Moreover, when the molten steel part (part in contact with the molten steel in the ladle) is used as a monitoring site, the erosion factor of the molten steel part is the amount of electric current and the stirring time of electromagnetic stirring. As a matter of course, in determining the monitoring part, a part that is likely to cause repair of the refractory and a part having a risk of leakage steel are selected.

Accumulated electric energy (arc electric energy, energized electric energy) is the time from construction to re-installation of all or part of the refractory (excluding repair) for the refractory installed in the molten iron container It is the integrated value of the amount of electric power consumed by the arc heating performed on the molten iron container. In other words, it is the period from the start of the refractory construction (repair) by using the molten iron container that has reached the end of its life and finished the construction (repair) of the refractory for secondary refining. The integrated value of the power consumption when arc heating is performed in the secondary refining process within the period becomes the above-described integrated power consumption.
(3) The amount of erosion at the monitoring site when the unit amount of the erosion factor is given (sometimes referred to as unit factor erosion amount) is determined (procedure 3). That is, in refining, the unit factor erosion amount of the monitoring site when a unit amount of erosion factor is applied is obtained.

As described above, when the monitoring site is a slag line part, the erosion factor is the amount of arc power. Therefore, it is considered to obtain the unit factor melting amount of the slag line portion.
First, when the relationship between the arc power amount (integrated power amount) and the amount of slag loss in the slag line portion is organized from the operation results, it is as shown in FIG.
As shown in FIG. 3A, when an approximate straight line between the measured residual thickness value of the slag line portion and the energized electric energy (integrated electric energy) accumulated in the LF device is obtained, y = −5 × 10 ⁻⁴ x + 200 (Y: refractory remaining thickness, x: accumulated electric energy). The slope (0.0005) of this approximate straight line is the unit factor erosion amount of the slag line portion.
(4) Regarding the erosion factor, the average amount per charge is obtained, and the amount of erosion per charge of the monitoring site (sometimes referred to as one charge erosion amount) is obtained from the average amount and the unit factor erosion amount. (Procedure 4). That is, the average amount of the erosion factor imparted per charge is obtained from the past operation results, and one charge erosion amount at the monitoring site is obtained from the average amount obtained from the past operation results and the unit factor erosion amount. One charge is a cycle from when molten metal is charged into a molten iron container until it is emptied.

For example, when the monitoring site is a slag line part and the erosion factor is the arc power amount in the LF device, the average arc power amount per charge is the average amount of the erosion factor. In this embodiment, the average arc power per charge, that is, the average amount of the erosion factor was 5000 kWh / ch.
Next, by substituting the average arc power amount per charge into the slope of the approximate straight line described above, the amount of melt loss per charge (one charge melt amount) of the monitored portion is obtained. In this embodiment, since the slope of the approximate line is 0.0005 mm / kWh, the average amount of the erosion factor is multiplied by 5000 kWh / ch, and the amount of erosion per charge of the slag line portion (1 The charge erosion amount) is obtained, and the value is 2.5 mm.
(5) A repair amount (kg) for increasing the refractory by 1 mm is obtained (procedure 5).

For example, the necessary repair amount for increasing the refractory by 1 mm is obtained from the difference between the melt loss amount when the spray repair is not performed and the melt loss amount when the spray repair is performed. In addition, there are hot spraying materials, baking materials, patching materials, etc. for repairing refractories.
In addition, in molten iron containers that have been repaired by spraying, the amount of erosion expected from changes in the refractory (estimated residual thickness) and the actual amount of erosion obtained from the measured refractory residual thickness (measured residual thickness) ) And dividing the difference by the amount of spraying, the amount of repair for increasing the refractory by 1 mm may be obtained. In this embodiment, the difference between the repair amount (kg) and the measured remaining thickness from the estimated remaining thickness is summarized in FIG. In the procedure (5), a repair amount for increasing the refractory by 1 mm may be obtained, and the method is not limited to the above contents.
(6) The end point judgment standard by the thickness of the refractory is determined from the use limit of the refractory (Procedure 6).

For example, in the case of a slag line portion, when the thickness of the refractory is less than 30 mm, the physical strength is lowered, and thus there is a possibility that the refractory is dropped or buckled. In some cases, permanent bricks closest to the iron skin may be exposed due to factors other than melting. In this embodiment, the end point determination criterion is that the remaining thickness of the refractory in the slag line portion is 30 mm or more.
In setting the end-point judgment criteria, based on the physical strength of the refractory and the infiltrated layer not to cause leakage or steel leakage, when providing a safety allowance (thickness considering safety) In addition, it is preferable to add to this end point determination criterion. As a matter of course, the safety allowance is set so that the refractory is not dropped or perforated according to the past operation results.

As mentioned above, the procedure of (1)-(6) is a matter performed before use of a molten iron container according to the process of using a molten iron container.
For example, as described above, when the molten iron container is repeatedly used in the LF apparatus, the monitoring site is the slag line portion, and the erosion factor is the arc power. And in each procedure, the amount of slag line erosion when the unit amount of arc power is applied (unit factor erosion amount), the average amount of arc power per charge, the amount per slag line charge The amount of erosion (1 charge erosion amount), the amount of repair for increasing the refractory by 1 mm, and the end point judgment standard of the slag line part are obtained.

Next, the procedure for using the molten iron container will be described.
In the description of the procedure when using the molten iron container, for the sake of convenience of explanation, an example in which the monitoring site is the slag line portion and the melting factor is determined as the arc power amount will be described.
In this embodiment, the operation was performed under the conditions shown in Table 1.

While the molten iron container is being used in the LF device (secondary refining), the remaining thickness of the refractory at the monitoring site is estimated based on the operation results of the (7) erosion factor at the stage where the predetermined charge is performed. (Procedure 7).
The remaining thickness of the refractory can be calculated using the construction amount of the initial slag line part (the thickness of the refractory immediately before the start of refining) and the unit factor erosion amount of the slag line part. Can be obtained from the amount of construction of the initial slag line portion-the integrated arc power amount (integrated power amount) at the predetermined charge × the unit factor erosion amount of the slag line portion.

For example, if the construction amount of the initial slag line portion is 200 mm, the arc power amount (integrated power amount) of the 18th charge is 90000 kWh, and the unit factor erosion amount of the slag line portion is 0.0005 mm, the fire resistance of the 18th charge The estimated value of the remaining thickness of the object is 155 mm according to the above formula.
(8) Measure the remaining thickness of the refractory during use of the molten iron container. Specifically, the remaining thickness of the refractory for the estimated same charge is measured with a general refractory remaining thickness measuring device (procedure 8). As a measurement technique, a physical measurement method using a scale, a laser profile meter, an ultrasonic meter, and an FM sensor, and a method for estimating the remaining thickness of the refractory from the temperature of the iron skin are also conceivable.
(9) The estimated remaining thickness of the refractory is compared with the actually measured remaining thickness of the refractory.

Specifically, the estimated value of the remaining thickness of the refractory estimated in the procedure (7) is compared with the measured value of the remaining thickness of the refractory actually measured in the procedure (8) (procedure 9), and the spray repair is performed. It is judged whether repair of refractories such as is necessary.
(10) When the measured residual thickness of refractory (actual value) is smaller than the estimated residual thickness of refractory (estimated value), the actual thickness is calculated based on the repair amount obtained in step (5) according to the difference. The repair amount is obtained and repaired (procedure 10).
That is, in the procedure (10), when the actual thickness of the refractory is melted more than the estimated remaining thickness, the refractory is repaired by a method such as spraying.

For example, in the 18th charge, if the estimated value is 155 mm as shown in the procedure (7) and the actually measured value measured in the procedure (8) is 150 mm, the condition is satisfied in this procedure (10). The difference (155 mm−150 mm = 5 mm) is obtained. Then, the repair amount obtained in step (5) is added to the obtained difference of 5 mm, that is, the repair amount is obtained by substituting the difference into the slope (slope, 50) shown in FIG. Repair the monitored part at. For example, the repair amount is 50 (inclination) × 5 (difference) = 250 kg.
After repair, review the expected number of times of use of the molten iron container. Here, in obtaining the expected number of times of use, first, after subtracting the end point determination criterion determined in step (6) from the estimated value of the refractory, the thickness of the remaining refractory until reaching the end point determination criterion is determined. . And the number of times of scheduled use is calculated | required by dividing the thickness of this remaining power by 1 charge melt | disconnection amount of the slag line part calculated | required in the procedure (4).

  For example, in the 18th charge, when the estimated value of the refractory is 155 mm and the actual measured value of the refractory is 165 mm, the thickness of the surplus power is calculated according to the estimated value of the refractory (155 mm) -end point determination criterion (30 mm). Is 125 mm. And the remaining usage count is 50 charges due to the remaining power thickness (125mm) ÷ 1 charge melt loss amount (2.5mm / ch) in the slag line part. The number of times is 68 charges. As a matter of course, the decimal point is rounded down when calculating the planned number of times of use.

(11) When the actually measured remaining thickness of the refractory is larger than the estimated remaining thickness of the refractory, the estimated number of times of use of the molten iron container is reviewed using the estimated remaining thickness and the amount of one charge erosion (procedure 11). ).
In this procedure (11), even if the actual measured value of the remaining thickness of the refractory, that is, the actual thickness of the refractory is larger than the estimated value of the estimated refractory, the estimated value is used as a reference in consideration of the safety factor. In addition, the expected number of times of use of the molten iron container (the number of times the steel can be received as viewed from the refractory) is obtained.
Specifically, in determining the expected number of times of use, the method is the same as in the above-described procedure (10). First, after subtracting the end point determination criterion determined in step (6) from the estimated value of the refractory, the end point is determined. Find the remaining thickness of the refractory until it reaches the criterion. And the number of times of scheduled use is calculated | required by dividing the thickness of this remaining power by 1 charge melt | disconnection amount of the slag line part calculated | required in the procedure (4).

For example, in the 18th charge, when the estimated value of the refractory is 155 mm and the measured value of the refractory is 165 mm, the scheduled number of use is 68 charges.
(12) If the scheduled use number is smaller than the next use number, the molten iron container is taken out for repair (procedure 12). That is, when the number of uses in the next charge is larger than the estimated number of uses obtained above, the molten iron container is taken out for repair. As a matter of course, when the molten iron container is to be repaired, if the refining process is a hot metal preliminary process, the molten iron container is transported to the converter, and the molten iron is charged into the converter and then sent to the repair. In the case of secondary refining, the molten iron container is transported to a casting process such as a continuous casting apparatus, and the molten steel is charged into the continuous casting apparatus before being repaired.

In the procedure (12), if the molten iron container is used for the next charge, the actual remaining thickness of the refractory may exceed the end point criterion (there may be less than the operating limit remaining thickness). After comparing the number of times of use with the number of times of next use (the value obtained by adding 1 charge to the current charge), if the condition according to step (12) is satisfied, the molten iron container is sent for repair and the refractory is reconstructed. Is going to do. The refractory is reconstructed at a place different from the LF device, for example, at a maintenance shop.
For example, in the 65th charge, if the accumulated arc power is 338000 kWh, the unit factor erosion amount of the slag line part is 0.0005 mm, and the construction amount of the initial slag line part is 200 mm, The estimated value of the remaining thickness is 31.0 mm. The remaining number of uses is 0 charge due to the surplus power thickness (1.0 mm) / melting loss amount per charge of the slag line part (2.5 mm / ch). When combined with the current charge (65 charges), The scheduled number of uses is 65 charges.

Here, since the number of times of the next use becomes the 66th charge, the condition shown in the procedure (12) is satisfied, so that the use of the molten iron container in the LF apparatus (secondary refining) is finished, and the molten iron container is used. Transport to a maintenance shop to repair refractories.
In step (12), the thickness of the surplus power is 1.0 mm, and it is clear that it is smaller than 2.5 mm per charge. Therefore, when the surplus power thickness is obtained, the molten iron container is repaired. May be. Moreover, when a molten iron container is used in the next charge, it becomes 28.5 mm, and since the estimated value of the refractory falls below 30 mm, which is the end point determination criterion, it may be determined that repairs are made.
(13) If the scheduled number of times of use is larger than the next number of times of use, the molten iron container is also used for the next charge, and the above (7) to (12) are repeated (procedure 13). That is, when the number of times of use in the next charge is smaller than the scheduled number of times of use, the molten iron container is also used for the next charge, and the above (7) to (12) are repeated.

In the procedure (13), even when the molten iron container is used in the next charge, there is a margin because the actual remaining thickness of the refractory reaches the end point determination criterion. Therefore, when the condition shown in the procedure (13) is satisfied The molten iron container will be used repeatedly for the next charge.
(14) However, if the remaining thickness of the refractory cannot be measured in step (8), after reviewing the estimated number of times of use of the molten iron container using the estimated remaining thickness and 1 charge erosion amount, The above (7) to (12) are repeated.

In step (14), the specific method for reviewing the estimated number of times of use of the molten iron container using the estimated remaining thickness and the one-charge erosion amount is the same as the method described above. That is, in obtaining the expected number of times of use in step (14), first, after subtracting the end point determination criterion determined in step (6) from the estimated value of the refractory, the refractory material until the end point determination criterion is reached. Find the thickness of the remaining power. Then, the number of times of scheduled use is obtained by dividing the thickness of this surplus force by the amount of erosion per charge of the slag line portion obtained in the procedure (4).
According to the present invention, as described above, by managing the refractory in the molten iron container according to the procedure (1) to the procedure (14), the leakage of the molten iron (leakage, steel leakage) from the molten iron container is ensured. In addition to being able to prevent, the refractory in the molten iron container can be used systematically as far as possible.

  Usually, the measurement of the remaining thickness of the refractory is performed in a hot state, so the measurement method is limited and the measurement accuracy is limited, but according to the present invention, the remaining refractory during refining due to various factors. Even if the thickness cannot be measured, the degree to which the refractory in the molten iron container has melted is calculated based on the operation results, so that the remaining thickness of the refractory can be estimated. The use limit of the molten iron container can be easily obtained. In other words, planned molten iron containers can be planned by performing refractory repairs, end point determination, etc. while predicting the transition of the remaining thickness of the refractory based on the operation results and monitoring the remaining thickness of the refractory by actual measurement of the refractory. Refractories can be used.

The effect by this invention is demonstrated in detail for every procedure.
In the previous stage of using the molten iron container, as shown in the procedure (1) to the procedure (2), the monitoring site and the erosion factor are determined in advance according to the operation content, and then the procedure (3) Since the amount of erosion per unit amount (unit factor erosion amount) is obtained as shown in Fig. 5, the erosion amount at the monitoring site can be estimated (predicted) from the operation results of the erosion factor. Further, as shown in the procedure (4), since the amount of one charge erosion of the monitored part is obtained, it is possible to easily obtain the expected number of times of use of the remaining molten iron container from the charge (current charge). .

Moreover, as shown in the procedure (5), by obtaining the repair amount for increasing the refractory by 1 mm, the thickness of the refractory after the repair can be accurately grasped. Even when the thickness of the object becomes thin, it becomes possible to manage the refractory in the molten iron container. As shown in the procedure (6), since the end point determination criterion is set, it is possible to reliably set the scheduled number of times of use and determine the end point in refractory management (molten iron container management).
As shown in the procedure (7), since the remaining thickness of the refractory in the monitoring part is estimated based on the operation results of the erosion factor during use of the molten iron container, the visual judgment of the manager who manages the molten iron container And unstable elements such as judgment based only on the measured value of the refractory residual thickness measuring device can be eliminated. In other words, because the estimated value of the refractory is used, the measurement results of the refractory residual thickness measuring device may be incorrect (such as errors due to adhesion of metal or slag or errors due to built-up). It is possible to reliably eliminate mistakes in determining the end point. Moreover, even if the thickness of the refractory cannot be measured by a refractory residual thickness measuring device, etc., the estimated number of times of use of the molten iron container can be predicted using the estimated value, so that the number of times of use of the molten iron container is surely reviewed after the end of one charge. It can be carried out.

In addition to the procedure (7), as shown in the procedure (8), since the remaining thickness of the refractory is measured during use of the molten iron container, both the estimated value of the refractory and the actual value of the refractory are calculated. It is possible to grasp the refractory melt condition from both sides, and the reliability of the end point determination is greatly improved.
In the procedure (10), when the actually measured remaining thickness of the refractory is smaller than the estimated remaining thickness of the refractory, the actual repair amount is obtained based on the repair amount obtained in the procedure (5) according to the difference. Since the repair is performed, the refractory can be managed after the refractory is returned to the same thickness as the actual measurement even in a situation where the melting loss is more advanced than estimated. As a matter of course, when spray repair is not performed or the amount of repair is small, the refractory melts faster than planned and must be repaired with a small number of uses. There is concern about the deterioration of the unit.

  In step (11), if the measured remaining thickness of the refractory is greater than the estimated remaining thickness of the refractory, the estimated number of times of use of the molten iron container is reviewed using the estimated remaining thickness and the amount of 1-charge erosion loss. ing. The fact that the actually measured remaining thickness of the refractory is larger than the estimated remaining thickness of the refractory means that the refractory is not melted more than expected in a predetermined charge, and the refractory has a margin. Usually, it seems reasonable to review the number of times of scheduled use of the molten iron container using the measured value of the refractory with a margin, but when reviewing the number of times of scheduled use, the present invention estimated from the viewpoint of safety. Estimated values are used.

In addition, according to the present invention, since the expected number of times of use is predicted in step (11), the remaining number of times of use of the molten iron container can be grasped, considering the remaining number of times of use, The timing of preparation of the molten iron container can be measured, and the construction plan of the refractory in another molten iron container can be adjusted.
On the other hand, in the present invention, even when the measured value of the remaining thickness of the refractory is smaller than the estimated value of the remaining thickness of the refractory, the scheduled number of times of use of the molten iron container is reviewed. In this case, it is better to review the expected number of times of use of the molten iron container using the actual measured value rather than the estimated value of the remaining thickness of the refractory, but in the present invention, the refractory The estimated number of times of use of the molten iron container is reviewed using the estimated value of the remaining thickness. However, when revising the estimated number of times the molten iron container is used using the estimated value of the remaining thickness of the refractory, as described above, repair the refractory and estimate the remaining thickness of the refractory and the actual refractory. The remaining thickness of steel is made the same, and the thickness of the substantial refractory is increased, and the planned number of times of use of the molten iron container is reviewed.

In step (14), if the remaining thickness of the refractory cannot be measured in step (8), the estimated number of times of use of the molten iron container should be reviewed using the estimated remaining thickness and the amount of erosion per charge. After performing, said (7)-(12) is repeated.
In actual operation, it is not always possible to measure the remaining thickness of the refractory for each charge. For example, in secondary refining with an LF device or the like, if the refining process time must be shortened or a large amount of metal or slag adheres to the surface of the refractory, measurement of the remaining thickness of the refractory can result. Due to operational restrictions when it is not possible, the remaining thickness of the refractory may not be measured.

In addition to the above operational restrictions, there are cases where the measured value of the refractory is abnormal in view of the actual thickness of the refractory.
Considering the case where the remaining thickness of the refractory cannot be measured due to operational restrictions, measurement errors, etc., if the remaining thickness of the refractory cannot be measured in step (14), the estimated remaining thickness And (7) to (12) are repeatedly performed after reviewing the expected number of times of use of the molten iron container using the amount of melting loss per charge. In this way, by incorporating a procedure that assumes that the remaining thickness of the refractory cannot be measured, even if the remaining thickness of the refractory cannot be measured, systematically manage the refractory in the molten iron container. Can do.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a flowchart which shows the procedure of the management method of the refractory of a molten iron container. This is a summary of the factors that end the secondary refining process. It is a related figure of the remaining thickness measured value (melting loss amount) of the refractory of a slag line part, and an integrated electric energy. It is a related figure of the amount of repairs (the amount of spray repair execution) and the difference between the estimated remaining thickness and the measured remaining thickness.

Claims (1)

A method for managing a refractory in a molten iron container, characterized in that the remaining thickness transition of the refractory provided in the molten iron container is managed according to the following procedure.
(1) Determine the monitoring site to be monitored before using the molten iron container.
(2) Determine the erosion factor that contributes to the erosion loss at the monitoring site.
(3) The unit factor erosion amount of the monitoring site when the unit amount of erosion factor is applied is determined.
(4) The average amount of the erosion factor imparted by one charge is determined, and the one-charge erosion amount per charge of the monitored portion is determined from the average amount and the unit factor erosion amount.
(5) The repair amount for increasing the refractory by 1 mm is obtained.
(6) Establish end point criteria based on the thickness of the refractory from the limit of use of the refractory.
(7) Estimate the remaining thickness of the refractory at the monitoring site based on the operation results of the erosion factor during use of the molten iron container.
(8) Measure the remaining thickness of the refractory during use of the molten iron container.
(9) The estimated remaining thickness of the refractory is compared with the actually measured remaining thickness of the refractory.
(10) When the remaining thickness of the measured refractory is smaller than the estimated remaining thickness of the refractory, the actual repair amount is determined based on the repair amount determined in (5) according to the difference, and repair is performed. The estimated number of times of use of the molten iron container is reviewed using the estimated remaining thickness and the one-charge erosion amount.
(11) Even if the measured remaining thickness of the refractory is larger than the estimated remaining thickness of the refractory, the estimated number of times of use of the molten iron container is reviewed using the estimated remaining thickness and the one-charge erosion amount. I do.
(12) If the number of uses in the next charge is greater than the planned number of uses, the molten iron container is taken out for repair.
(13) When the number of uses in the next charge is smaller than the planned number of uses, the molten iron container is also used for the next charge, and the above (7) to (12) are repeated.
(14) However, if the remaining thickness of the refractory cannot be measured in (8) above, after reviewing the estimated number of times of use of the molten iron container using the estimated remaining thickness and 1 charge erosion amount, The above (7) to (12) are repeated.