JP3465609B2 - Hot metal inventory management method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention stocks hot metal tapped from a plurality of blast furnaces in a specific range in the range of these blast furnaces and steelmaking factories when used in a plurality of steelmaking plants in a specific range. The present invention relates to a hot metal inventory management method for grasping the amount of hot metal. In particular, it not only reduces the amount of calculation for grasping inventory, but also improves inventory grasping accuracy, and reduces blast furnace sudden wind reduction due to excessive hot metal, or The present invention relates to a hot metal inventory management method capable of preventing production loss due to inventory shortage and reducing the labor and cost required for inventory management and correction of operation based on the inventory management. In addition, the above-mentioned specific range includes an integrated steel mill in which hot metal tapped from a plurality of blast furnaces is used in a plurality of steelmaking plants and cast iron plants.

[0002]

2. Description of the Related Art Hot metal that has a plurality of blast furnace groups and a plurality of steelmaking plants, and the hot metal that is tapped from the blast furnace groups in the plant is the amount of hot metal in stock in the integrated steelworks used in the steelmaking plant in the plant. Need to be grasped correctly. When the stock runs out, the post-process operations below the steelmaking plant will be delayed. On the other hand, when the inventory overflows, in the worst case, the blast furnace will be shut down.

Regarding the physical distribution by a computer and energy management methods in integrated steelworks up to now, for example, Japanese Examined Patent Publication Nos. 44-3158 and 52-18416 can be cited. These are operation management methods in which a predetermined operation pattern is input to a computer, a necessary action is taken when an unexpected situation occurs, and a person corrects it. However, the actual logistics of the integrated steelworks are changing from time to time, and in many cases unforeseen situations occur, requiring constant human corrections.

On the other hand, from the viewpoint of "unified management of multiple processes" in an integrated steel mill, "JP-A-61-22711"
The invention according to 0 is mentioned. According to the present invention, the unit of calculation is divided into blocks having the following four functions in order to centrally manage the process from the blast furnace to the steelmaking plant.

A1. Calculation of required hot metal amount for each process: Calculate the required hot metal amount in a steel manufacturing plant during a predetermined period T from a preset time Ti to Tj from the number of tapping charges, the hot metal rate, and the stocked amount of stock in the predetermined period T To do.

A2. Prediction of the amount of hot metal and the amount of hot metal components: Various blast furnace component data such as the amount of hot metal to be tapped during the predetermined period T, for example, past weighing results, fluctuations of coke and iron ore charging pitch in the hearth, etc. In consideration of the above, the amount of hot metal from the blast furnace during the predetermined period T is predicted by the autoregressive model. Furthermore, the tapping composition and temperature are predicted by the autoregressive model from the furnace top gas composition, furnace body heat dissipation, past composition, and temperature performance.

A3. Judgment of whether or not hot metal can be supplied: Is it possible to supply the hot metal such as the required components and temperature to each factory by taking into consideration the target amount and component values such as the required hot metal amount and hot metal hot metal amount obtained in A1 and A2 above? Predict whether or not. Only when it is judged that the supply is not possible, the out-of-furnace components are adjusted in the blast furnace, and when it is not possible, the supply to other plants or the inventory adjustment of TOPEED is performed, and the optimum operation pattern is selected each time.

A4. Implementation of operations corresponding to time: A3
Using the optimum pattern determined by, prepare the toeped under the gutter before the time Ti.
At the same time, tapping starts and ends at time Tj.

On the other hand, as a technique for similarly performing detailed scheduling in each process, Japanese Patent Laid-Open No. 09-24990.
3 is mentioned. This is also by collectively managing the hot metal inventory, tapping, and tapping schedule from the blast furnace to the steelmaking plant, and by linking the hot metal at the time of tapping the blast furnace and the ordered orders in a one-to-one relationship, Time management of the intermediate process is implemented.

[0010]

However, while such a fine control method seems to be meticulous and advantageous at first glance, it has the following drawbacks.

B1. It is possible to predict the amount of hot metal required in a steelmaking plant within a given period of time, but there is a large variation in the tapping speed, especially when there is a large difference between the start of tapping and the end of tapping. Even if the actual charging is taken into account, the predicted value and the actual value often deviate greatly. For this reason, it is difficult to match the hot metal consumption in the blast furnace and that in steelmaking in a one-to-one manner on a per-tope basis or on a blow-charging basis.

B2. When the required amount of hot metal in steelmaking and the predicted hot metal tapping schedule in the blast furnace are the same, mutual information will be advantageous for implementing hot metal inventory management. However, in addition to the difference in the "amount" of tapping metal indicated by B1, there is a factory with multiple component adjusting functions from the blast furnace to the steelmaking factory. Due to the lag of "time", it is impossible to match the hot metal consumption in the blast furnace and the steelmaking plant in a one-to-one manner in the unit of speede or the unit of blowing charge in the actual operation.

B3. When the quantitative and temporal “deviation” shown in B1 and B2 above occurs, the tapping is not carried out until the tapping time (Ti), which is estimated from the use time of the hot metal in steelmaking,
Careful operation management in which blowing and tapping are in one-to-one correspondence, such as starting tapping for the first time at time Ti, is completely meaningless, and rather the blast furnace tapping operation is subject to time constraints The loss is increased and the turnover rate of the speeded car is reduced. If the rotation rate is lowered, the thermal loss of the hot metal is unavoidably increased, and therefore the total cost is disadvantageous in comparison with the method in which the time constraint of the blast furnace is not imposed.
Regarding the relationship between such a decrease in rotation rate and heat loss,
An example thereof is described in JP-A-4-280908.

The operations between the blast furnace and the steelmaking plant are collectively controlled as shown in the invention of JP-A-61-227110,
Moreover, when each process from the blast furnace to the steelmaking is operated in a one-to-one manner, there is also a problem regarding calculation load.

Since the amount of information to be handled in this calculation is huge, the process computer requires a large capacity, and it is difficult to store and process other hot metal management information, for example, hot metal component information, in the same computer, or In some cases it becomes impossible. For this reason, it is necessary to prepare a computer with a very large calculation capacity or to prepare a separate computer for carrying out the hot metal inventory calculation. This not only increases the cost for inventory management, but in the latter case, it becomes impossible to capture other information required for schedule management online, and conversely the calculation efficiency deteriorates.

Further, in the case where there is a one-to-one correspondence between the conventional steelmaking and the blast furnace, there is a problem in calculation accuracy.

That is, in the calculation, not only the calculation load is large, but also the schedule is largely deviated due to the variation of the transportation time between the factories, so that the inventory calculation accuracy is deteriorated. Therefore, there has been a problem that there is a sudden reduction in wind due to excessive hot metal inventory caused by a decrease in calculation accuracy, or a production amount has not been reached due to a shortage of hot metal inventory.

The present invention has been made to solve the above-mentioned conventional problems, and not only reduces the amount of calculation for grasping the inventory but also improves the accuracy of grasping the inventory and reduces the blast furnace burst due to excess hot metal. An object of the present invention is to provide a hot metal inventory management method capable of preventing production loss due to wind or insufficient inventory, and reducing the labor and cost required for the inventory management and correction of operation based on the inventory management. .

[0019]

According to the present invention, when hot metal tapped from a plurality of blast furnaces in a specific range is used in a plurality of steelmaking plants in a specific range, the hot metal is stocked in the range of these blast furnaces and steelmaking plants. In the hot metal inventory management method for grasping the amount of hot metal that is present, a step of grasping the amount of hot metal released from the blast furnace group in a predetermined future period based on the current production status, and a production schedule The step of ascertaining the required amount of hot metal used in the steelmaking factory group in the predetermined period, the step of ascertaining the current amount of hot metal inventory in the specific range, the amount of hot metal tapped and the required amount of hot metal and the above The present invention has been made to solve the above problems by providing a step of estimating the hot metal inventory amount for the predetermined period based on the current hot metal inventory amount and grasping the hot metal inventory in the specific range.

Further, in the above-mentioned hot metal inventory control method, when using the hotpe when the hot metal is transported from the blast furnace to the steelmaking plant, the amount of the hot metal tapped is the speed at which the hot metal is supplied from the blast furnace to the tope. , And according to the elapsed time of the supply, the required amount of hot metal, the speed of discharging the hot metal from the topeed to the pig iron factory and / or the steelmaking factory, and so as to be obtained according to the elapsed time of the discharge By doing so, while the hot metal is supplied from the blast furnace to the tope and loaded, or when a required amount is loaded, while the hot metal is discharged from the tope to the cast iron factory and / or the steelmaking factory or discharged. It is possible to accurately grasp the hot metal inventory at the time of completion.

The operation of the present invention will be briefly described below.

In the present invention, when hot metal tapped from a plurality of blast furnaces in a specific range is used in a plurality of steelmaking plants in a specific range, the amount of hot metal in stock in these blast furnaces and steelmaking factories is controlled. The method of inventory management of hot metal to grasp is a prerequisite. As an example of the specific range for grasping the stock amount, there is an integrated steel mill. Alternatively, it may include some blast furnaces, steelmaking plants, and cast iron plants, including such integrated steelworks, within a range where hot metal can be transported.

Prior to computerization, humans conventionally grasped the hot metal inventory based on manual calculation and experience, and operated it in an integrated steelworks. Conventionally, when trying to computerize this, complicated calculations have been performed.
However, the present invention has been made paying attention to the fact that, even if a computer is used in this way, not only does the calculation result obtained by humans not match, but also a problem occurs due to a failure in inventory management.

In the present invention, the basic idea of a simple calculation method and judgment by a human being is investigated, arranged and adjusted, and it is put together as a hot metal inventory management method. The hot metal inventory management method of the present invention can also be introduced into a calculation system, and a simplified and user-friendly system can be constructed as compared with a conventional computerized system.

In the present invention, it is possible to estimate the hot metal stock quantity immediately after the predetermined period based on the hot metal hot metal quantity, the required hot metal quantity, and the present hot metal stock quantity. We pay attention to the estimation method of. Also, these amounts are calculated as simply as possible.

That is, in the present invention, the amount of hot metal tapped from the blast furnace group in a predetermined future period is grasped based on the current production situation. Further, the required amount of hot metal used in the steelmaking factory group during the predetermined period is grasped based on the production schedule. Further, the present amount of hot metal stock in the specific range is grasped. With such a simple and small calculation method, first, the hot metal hot tapping amount, the required hot metal amount, and the present hot metal hot stock amount are obtained. In this way, the hot metal stock quantity for the predetermined period is estimated based on the hot metal hot metal quantity, the required hot metal quantity, and the current hot metal stock quantity. Such estimation is a simple operation such as addition or subtraction.

As described above, according to the present invention, not only the amount of calculation for grasping the inventory is reduced, but also the inventory grasping accuracy is improved, and the blast furnace sudden wind reduction due to excess hot metal or the production loss due to insufficient inventory. It is possible to prevent the occurrence and reduce the labor and cost required for the inventory management and the correction of the operation based on the inventory management.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

First, FIG. 1 is a block diagram showing a configuration of an arithmetic unit which realizes a hot metal inventory management method of an embodiment to which the present invention is applied.

In this figure, in the present embodiment, a hot metal hot metal amount grasping calculation unit 12, a required hot metal amount grasping calculation unit 14, a hot metal inventory amount grasping calculation unit 16, and a hot metal inventory amount estimating calculation unit 20 are shown.
It is realized by. These are realized by the program of the process control computer.

The hot-melt pig iron amount calculation unit 12 checks the hot-melt amount to be tapped from the blast furnace group in a predetermined future period based on the current production situation. The predetermined period is a unit of a period when the hot metal inventory management method to which the present invention is applied is performed, and is hereinafter simply referred to as a predetermined period. Further, the required hot metal amount grasping calculation unit 14 grasps the required amount of hot metal used in the steelmaking factory group in the predetermined period based on the production schedule. Next, the hot metal inventory amount calculation unit 16 further checks the current hot metal inventory amount in the specific range. in this way,
In the hot metal hot metal amount grasping calculation unit 12, the required hot metal amount grasping calculation unit 14, and the hot metal inventory amount grasping calculation unit 16, the amount of hot metal hot tapped, the required amount of hot metal, And the present hot metal inventory. These amounts of hot metal are those in the hot metal inventory management method to which the present invention is applied, and are referred to as these names below.

In this way, the hot metal inventory quantity calculation unit 20 estimates the hot metal stock quantity immediately after the predetermined period, based on the hot metal hot metal quantity, the required hot metal quantity, and the current hot metal stock quantity. . The stock amount is hereinafter referred to as an estimated hot metal stock amount. The estimation in the hot metal inventory amount estimation calculation unit 20 is a simple calculation such as addition and subtraction, and the calculation amount is small.

The calculation in this embodiment will be described below.

In the present embodiment, the hot metal inventory calculation is simplified in order to reduce the calculation load. The simplification of hot metal inventory calculation is as follows.

C1. Simplifying the amount of hot metal supplied in the blast furnace: Forecasting the amount of hot metal from the blast furnace does not carry out the simulation calculation that has been carried out in the past, but the past iron ore charging record and past tapping speed record Estimate based on 2 information.
As these record data, record data within the last 24 hours is preferably used. In addition, the amount of tapping at each time is estimated by setting a constant value during the normal operation in which the air flow rate is not changed, and by providing several patterns for each of the decreasing and increasing wind operations.

C2. Simplified calculation of hot metal usage speed in steelmaking:
The amount of hot metal used in steelmaking is calculated from the amount of hot metal used for each operation unit and the hot metal charging interval based on the operation schedule for a predetermined period from the present. This predetermined period is preferably 24 hours. Further, in order to reduce the calculation load, a hot metal charging pitch (charge-charge interval) is not calculated online, but a reference table for each steel type is created based on past data and used. The above-mentioned hot metal charging pitch is the interval from the charging of the hot metal to the charging of the next hot metal.

C3. Independence and simplified calculation of schedule management between blast furnace and steelmaking: When grasping the hot metal inventory using the information of C1 and C2, the blast furnace tapping time and the steelmaking time, which have been conventionally implemented, are set to 1 In the present embodiment, the so-called "stringed" operation in which the correspondence is one-to-one is not performed. The stringed operation is an operation in which, at the start of tapping, the topede determines which charge and when to use at the steelmaking plant. In the present embodiment, the future hot metal inventory amount after a predetermined period, that is, the estimated hot metal inventory amount is estimated by a simple calculation such as the following equation (1). As described above, in the present embodiment, only the balance between supply and demand after a predetermined period is taken into consideration, and the "tying" operation at the steelmaking use time and the tapping use time for each topeido is eliminated.

[0038]     Estimated hot metal inventory = current hot metal inventory + hot metal output-required hot metal amount (1)

Next, in the present embodiment, as described below, the hot metal inventory is corrected during the pig iron receiving to the tope and during the paying out from the tope to improve the calculation accuracy.

When the hot metal inventory is grasped, conventionally, when the hot metal is supplied into the tope or is discharged into another container, the process is completely finished (when the tope is full,
Until it becomes empty), the inventory does not fluctuate, and there are large fluctuations at the completion of pig iron reception and at the completion of discharge, which hinders the management of the inventory amount to an appropriate value. For example, when hot metal is supplied from a plurality of blast furnaces to a plurality of speeded cars (200 to 400 t / unit), if these hot metal supplies are finished at the same time, the inventory increase of 400 to 800 t will occur at once However, it is feared that a wrong judgment will be made in adjusting the hot metal inventory. In order to avoid such inventory fluctuation, the following method was devised in this embodiment.

D1. Regarding topede during piggybacking, when x is the elapsed time from the start of piggybacking to that todope,
A fictitious inventory quantity is predicted from the start of pig iron reception to the completion of pig iron reception by the second formula below, and the inventory quantity until completion of pig iron reception is managed as a continuous value.

[0042]     Inventory quantity of pigeons in receiving pigeon (t / unit)       = Tapping speed (t / h) x x (min) ÷ 60) (2)

D2. In the process of discharging the hot metal from the topeed to another container (for example, the process of discharging the hot metal to the pig iron machine at the pig iron factory, or the process of directly discharging it to the hot metal charging pot or the refining furnace at the steelmaking plant) When x is the elapsed time from the discharge of hot metal to the hot metal, the discharge amount is similarly continuously corrected and reflected in the hot metal inventory amount.

[0044]     Required amount of hot metal from Topeed during discharge (t / unit)       = Discharge rate (t / h) x x (min) ÷ 60) (3)

Here, FIG. 2 is a graph showing the supply of hot metal to the tope and the discharge from the tope to another container.

In this graph, time Ts is the start time of hot metal supply from the blast furnace to the tope or the start time of discharge from the tope to another container. Time Te is
It is the end time of the hot metal supply to the tope or the end time of the discharge from the tope to another container. Also, the amount of hot metal Wt
Is the load amount at the time when the supply from the blast furnace to the tope is completed, or the load amount immediately before discharging from the tope to another container.

Conventionally, it was simply understood that at time Te, the hot metal amount Wt was temporarily loaded as a batch at a time. Alternatively, simply at time Te, it was grasped as a batch of the amount of hot metal Wt discharged into another container at one time. On the other hand, in this embodiment, the amount of hot metal tapped W supplied from the blast furnace to the tope is determined by the speed of supplying the hot metal from the blast furnace to the tope, and the elapsed time of the supply, as indicated by the one-dot chain line in this graph. Ask for. At the same time, the amount of residual hot metal when discharged from the tope to another container is determined according to the speed of discharging the hot metal from the tope to the different container and the elapsed time of the discharge.

When the amount of hot metal remaining when discharged from the topede to another container is taken as the stock amount, it is represented by a chain double-dashed line in FIG.

As described above, the amount of hot metal to be supplied from the blast furnace to the tope is determined according to the speed at which the hot metal is supplied from the blast furnace to the tope and the elapsed time of the supply, or is discharged from the tope to another container. The required amount of hot metal to be, when determining according to the speed of discharging the hot metal from the topeed into the separate container, and the elapsed time of the discharge, carefully determine the amount of hot metal to be tapped and the required amount of hot metal according to the elapsed time. It does not have to be calculated continuously. Such a thing is also included in the present invention.

That is, from the time Ts to the time Te, these amounts of hot metal and residual hot metal may be obtained at appropriate time intervals. Alternatively, from the time Ts to the time Te, the amount of hot metal tapped or the amount of residual hot metal may be obtained at a time interval of about 2 to 4. By doing so, the frequency of obtaining these can be reduced, and thus the amount of calculation and the amount of calculation can be reduced as compared with the case where these are obtained in close succession. Further, even in this case, the stock amount of hot metal can be grasped more accurately than in the conventional case.

The present invention is carried out by using, for example, a computer as described above, and a preferable operation screen configuration for smoothing the processing will be described.

The operation screen is composed of a screen for displaying a predicted value of future hot metal inventory (referred to as an actual operation screen here) and a screen for inputting operation data and the like (referred to as an input screen here). preferable.

In the above-mentioned actual operation screen, the future inventory forecast value can be grasped promptly and online by showing the forecast value up to 24 hours after the present in the central portion of the screen. If the inventory forecast value exceeds a certain management range, a warning bell will be automatically notified to that effect, and the amount of tapping, steelmaking operation adjustment,
Alternatively, the hot metal inventory should be adjusted to an appropriate range by either adjusting the hot metal operation.

The above-mentioned data input screen is for predicting hot metal inventory. On this screen, information such as the tapping speed, the future pig iron schedule, the hot metal supply stop time, etc. is entered and automatically calculated. The automatic calculation result is reflected in the inventory calculation on the above-mentioned actual operation screen. The steelmaking use schedule and the planned hot metal use amount for each operation unit are automatically calculated, and can be grasped on a steelmaking schedule screen different from these two screens.

The effects of this embodiment will be described.

FIG. 3 is a graph showing a conventional hot metal inventory management (that is, a case where hot metal inventory management is performed by an operator's manual calculation), and FIG. 4 is a graph showing a transition of hot metal inventory performance of the present embodiment. or,
As a comparative example, FIG. 5 is a graph showing a transition of hot metal inventory results when the above-mentioned so-called linking management is performed. According to the comparative example, the one-to-one relationship breaks down as a result of time and quantity shifts at the steelmaking plant. Even so, if the one-to-one operation is continued, the hot metal inventory fluctuation will become large and the actual calculation function will be lost.

In the present embodiment, fluctuations in hot metal inventory during blast furnace tapping and hot metal discharge to another container are continuously processed. In addition, in these FIGS. 3 to 5, the horizontal axis represents time, which is represented by 0:00 to 23:00 in one day. The vertical axis represents the hot metal inventory.

As is clear from comparing these graphs,
By applying the present invention, the hot metal inventory fluctuation is reduced from a maximum of 700 t to 350 t per hour, and it becomes possible to perform a more true hot metal inventory management in real time.

FIG. 6 is a graph showing the distribution of the difference between the estimated inventory amount and the actual inventory amount calculated by this embodiment and manually.

This embodiment is processed by a computer. Further, in this graph, the estimation is made 8 hours later, that is, the above-mentioned predetermined period is 8 hours. From this figure, the difference between the case where the detailed hand calculation is executed and the case where the computer calculation according to the present invention is executed is only 40t.
It is understood that the hot metal inventory amount can be accurately predicted in this embodiment. With this, compared to the conventional
It has become possible to reduce the number of personnel who have been carrying out inventory calculations on-site. In addition, it is possible to reduce the number of sudden wind reductions due to excessive hot metal inventory from 4 times / year to 0 times / year by constantly displaying and displaying the inventory forecast for 24 hours after automatic calculation.

As described above, by applying the present invention, not only the calculation load of the computer is remarkably reduced, but also the operation from the conventional blast furnace to steelmaking is temporally and quantitatively reduced to 1
The calculation accuracy is improved as compared with the calculation result corresponding to 1 and it is possible to prevent blast furnace sudden wind reduction due to excessive hot metal or production loss due to insufficient inventory. Further, in order to improve the accuracy up to now, one dedicated operator was required, but with the improvement and simplification of the calculation accuracy, it becomes possible to unmannedly perform hot metal inventory management.

[0062]

According to the present invention, not only the amount of calculation for grasping the inventory is reduced but also the inventory grasping accuracy is improved,
It is possible to prevent a blast furnace sudden wind reduction due to excessive hot metal or a production loss due to inventory shortage, and reduce the labor and cost required for the inventory management and the operation modification based on the inventory management.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an arithmetic unit that implements a hot metal inventory management method according to an embodiment of the present invention.

FIG. 2 is a graph showing the supply of hot metal to the tope and the discharge from the tope to another container.

FIG. 3 is a graph showing the transition of hot metal inventory results by the conventional hot metal inventory management method.

FIG. 4 is a graph showing a transition of hot metal inventory results by the hot metal inventory management method of the embodiment.

FIG. 5 is a graph showing a transition of hot metal inventory results by a hot metal inventory management method of a comparative example.

FIG. 6 is a graph showing the distribution of the difference between the estimated inventory amount and the actual inventory amount calculated by the above embodiment and manual calculation.

[Explanation of symbols]

12 ... Calculator for grasping amount of hot metal 14 ... Required hot metal amount calculation unit 16 ... Hot metal inventory quantity calculation unit 20 ... Hot metal inventory amount calculation unit

   ─────────────────────────────────────────────────── ─── Continued front page       (56) Reference JP-A-9-249903 (JP, A)                 JP-A-61-227110 (JP, A)                 JP-A-51-81710 (JP, A)                 JP-A-61-238905 (JP, A)                 JP-A-6-172823 (JP, A)                 IE of Steel, Japan, Japan Iron and Steel               Federation, January 25, 1996, Vol. 34, No. 1               No. 36-44

Claims (2)

(57) [Claims] 1. When the hot metal tapped from a plurality of blast furnaces in a specific range is used in a plurality of steelmaking plants in a specific range, the amount of hot metal in stock in these blast furnaces and steelmaking plants is grasped. In the method for managing hot metal inventory, a step of ascertaining the amount of hot metal to be tapped from the blast furnace group in a predetermined future period based on the current production status, and a steelmaking schedule during the predetermined period based on a production schedule. A step of grasping the required amount of hot metal used in the factory group, a step of grasping the current hot metal inventory amount in the specific range, based on the amount of hot metal hot tapped, the required amount of hot metal and the current hot metal inventory amount, And a step of estimating the hot metal inventory amount for the predetermined period, so that the hot metal inventory in the specific range is grasped. 2. The method of managing hot metal inventory according to claim 1, wherein when hot metal is used for transporting hot metal from the blast furnace to the steelmaking plant, the amount of hot metal tapped is the hot metal from the blast furnace to the hot metal. And the required amount of hot metal, according to the speed of discharging hot metal from the topede to the pig iron factory and / or the steelmaking factory, and the elapsed time of the discharging. The method for managing hot metal inventory is characterized in that