A ladle circulation method for a continuous casting machine and a continuous casting production process

Abstract

The present application relates to the technical field of metal smelting, and particularly discloses a ladle circulation method of a continuous casting machine and a continuous casting production process to solve the problem of low ladle circulation rate in steelmaking-continuous casting production. The ladle circulation method of the continuous casting machine comprises: one of two continuous casting machines is operated with all casting flows opened, and the other is operated with part of the casting flows opened; the number of ladles corresponding to the two continuous casting machines respectively is determined according to the single-ladle casting cycle required by the two continuous casting machines respectively and the total circulation time of the ladles from tapping of the corresponding converter to casting of the continuous casting machine, and the number of ladles corresponding to the two continuous casting machines respectively is summed up to obtain the total number of ladles. The ladle circulation method has the beneficial effect of reducing the number of ladles, improving the ladle circulation rate, thereby reducing the tapping temperature of the converter, saving the energy consumption in the steelmaking process and the consumption of ladle baking gas. The present application also discloses a continuous casting production process adopting the ladle circulation method of the continuous casting machine, which also has the above technical effects.

Description

Technical Field

[0001] This invention relates to the field of metal smelting technology, and more specifically, to a ladle turnover method and continuous casting production process for a continuous casting machine. Background Technology

[0002] The ladle is a high-temperature vessel used for holding, transferring, and refining molten steel during the steelmaking-continuous casting process. In actual production, the ladle plays a crucial role, closely related to the stable control of molten steel temperature and the coordination of various processes within the steel plant. Currently, due to the complexity of steelmaking processes, frequent production anomalies, and the scheduling of equipment maintenance and continuous casting machine downtime for recasting, the constraints of actual ladle turnover have not been fully considered, resulting in low ladle turnover efficiency.

[0003] Taking a steelmaking-continuous casting production line as an example, it adopts two 120t top-and-bottom blowing converters, two sets of mechanical stirring hot metal desulfurization devices, two 120t LF refining furnaces, and two 10-strand small billet continuous casting machines for producing 160×160mm billets. 2 For cross-section casting billets, the number of steel ladles required is usually no less than 10, and the turnover rate of steel ladles is relatively low.

[0004] In summary, how to effectively solve the problem of low ladle turnover rate in steelmaking-continuous casting production is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a ladle turnover method and continuous casting production process for a continuous casting machine, which can effectively solve the problem of low ladle turnover rate in steelmaking-continuous casting production.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A ladle turnover method for a continuous casting machine, used in a production line with two identical converters corresponding to two identical continuous casting machines, comprising:

[0008] One of the two continuous casting machines is operated with all the casting flow open, while the other is operated with only part of the casting flow open.

[0009] Based on the single-furnace casting cycle required for each of the two continuous casting machines and the total turnaround time of the ladle from the corresponding converter to the continuous casting machine, the number of ladles corresponding to the two continuous casting machines is determined, and the total number of ladles is obtained by summing them.

[0010] Optionally, in the above-mentioned ladle turnover method for continuous casting machines, one of the two continuous casting machines operates with all ten casting streams open, while the other operates with five casting streams open.

[0011] Optionally, in the above-mentioned ladle turnover method for continuous casting machines, the converter is a 120-ton converter, and the total number of ladles ranges from 7 to 8.

[0012] Optionally, the above-mentioned ladle turnover method for continuous casting machines also includes:

[0013] If the ladle is produced, then additional ladles that meet the baking requirements are added to meet the total number of ladles.

[0014] Optionally, in the above-mentioned ladle turnover method for continuous casting machines, the total turnover time is specifically the sum of the single-furnace casting cycle of the continuous casting machine, the smelting cycle of the corresponding refining furnace, the corresponding slag removal and hot repair time, the preparation cycle from the completion of the corresponding hot repair to the start of the converter steel discharge, and the steel discharge cycle from the start of the converter steel discharge to the start of the refining furnace smelting.

[0015] Optionally, in the above-mentioned ladle turnover method for continuous casting machines, the slag removal and hot repair time specifically includes the slag removal and hot repair time for the sprue slide plate replacement operation.

[0016] Optionally, in the above-mentioned ladle turnover method for continuous casting machines, determining the number of ladles corresponding to the two continuous casting machines respectively includes:

[0017] The total turnaround time is divided by the corresponding single-furnace casting cycle and rounded up to obtain the number of ladles corresponding to the continuous casting machine.

[0018] The ladle turnover method for continuous casting machines provided by this invention is applied to a production line with two converters corresponding to two continuous casting machines. By operating one of the two continuous casting machines with all casting flow open and the other with only partial casting flow open, and based on the required single-furnace casting cycle for each machine and the total turnover time of the ladle from the corresponding converter tapping to the continuous casting machine, the number of ladles corresponding to each machine is determined, and then summed to obtain the total number of ladles. The beneficial effects of this ladle turnover method are that by operating one continuous casting machine with all casting flow open and the other with only partial casting flow open, it better matches the converter, ensuring the casting speed of the continuous casting machine, reducing the number of ladles, and increasing the ladle turnover rate. This reduces refining power consumption, electrode consumption, gas consumption, and the overall temperature drop of molten steel, enhancing the operational stability of the steelmaking system and achieving significant energy savings, particularly in reducing converter tapping temperature and saving energy consumption during steelmaking and ladle baking gas consumption. Furthermore, the ladle turnover method provided by this invention does not require the addition of other equipment and can be successfully implemented under existing production conditions.

[0019] To achieve the above objectives, the present invention provides the following technical solution:

[0020] A continuous casting production process, comprising:

[0021] Converter steelmaking;

[0022] Refined;

[0023] Continuous casting, wherein the ladle turnover method of any of the above-mentioned continuous casting machines is used for ladle turnover during the continuous casting process.

[0024] The beneficial effects of applying the continuous casting production process provided by this invention are that by operating one continuous casting machine with all the casting flow open and another continuous casting machine with only part of the casting flow open, it can better match the converter, ensure the casting speed of the continuous casting machine, reduce the number of tundishes, and improve the tundish turnover rate, thereby reducing refining power consumption, electrode consumption, gas consumption, and the temperature drop of molten steel throughout the process, enhancing the operational stability of the steelmaking system, and achieving significant energy-saving effects, especially reducing the converter tapping temperature and saving energy consumption in the steelmaking process and ladle baking gas consumption. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a ladle turnover method for a continuous casting machine according to a specific embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the ladle turnover path. Detailed Implementation

[0028] This invention discloses a ladle turnover method and continuous casting production process for a continuous casting machine, in order to improve the ladle turnover rate.

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Iron and steel smelting generally includes processes such as converter blowing, ladle refining, and continuous casting. Iron ore is smelted into pig iron in a blast furnace, and the molten iron is poured into a converter to smelt into steel. The steel is then refined in a refining furnace, and the qualified molten steel is sent to a continuous casting machine to cast continuously cast billets or ingots. These are then processed into various steel products for different applications through plastic deformation methods such as rolling. The ladle is the molten steel transport device in the continuous casting machine. In this application, the ladle turnover rate is improved through the design of the continuous casting machine's ladle turnover system.

[0031] Please see Figure 1 , Figure 1 This is a schematic diagram of a ladle turnover method for a continuous casting machine according to a specific embodiment of the present invention.

[0032] In one specific embodiment, the ladle turnover method for continuous casting machines provided by the present invention is used for production lines with two converters of the same specifications corresponding to two continuous casting machines of the same specifications. The ladle turnover method includes:

[0033] S1: One of the two continuous casting machines is operated with all the casting flow open, while the other is operated with only part of the casting flow open;

[0034] S2: Based on the single-furnace casting cycle required for each of the two continuous casting machines and the total turnaround time of the ladle from the corresponding converter tapping to the continuous casting machine casting, determine the number of ladles corresponding to each of the two continuous casting machines, and sum them to obtain the total number of ladles.

[0035] It is understood that steps S1 and S2 above are not intended to limit the order of execution. Continuous casting is a production process in which high-temperature molten steel is continuously poured into a billet with a certain cross-sectional shape and size. The continuous casting machine is the equipment used in this process. It continuously pours high-temperature molten steel into one or a group of water-cooled copper crystallizers. The molten steel gradually solidifies into a billet shell along the periphery of the crystallizer. After the molten steel level rises to a certain height and the billet shell solidifies to a certain thickness, the straightener pulls the billet out, and it is cooled by water spray in the secondary cooling zone to completely solidify the billet. The cutting device then cuts it into fixed lengths according to the requirements of steel rolling. Continuous casting machines usually have multiple crystallizers, corresponding to the simultaneous production of multiple casting streams. In conventional continuous casting operations, multiple casting streams of the continuous casting machine operate simultaneously. To meet the production matching requirements with the converter, it is usually necessary to reduce the casting speed of the continuous casting machine. In this application, by operating one of the two continuous casting machines with all casting streams open and the other with only a portion of the casting streams open, better matching with the converter can be achieved.

[0036] The required number of ladles for each of the two continuous casting machines is determined based on their respective single-heat casting cycles and the total turnaround time of the ladle from the corresponding converter tapping to the continuous casting machine. The single-heat casting cycle of a continuous casting machine is determined by the current flow of castings. The total ladle turnaround time is the total time from converter tapping to the completion of a single-heat casting in the continuous casting machine. The required number of ladles for each continuous casting machine can be calculated from its total turnaround time and single-heat casting cycle. The total number of ladles for each continuous casting machine is obtained by adding the number of ladles for each machine.

[0037] The ladle turnover method for continuous casting machines provided by this invention, by operating one continuous casting machine with all casting flow open and another continuous casting machine with only partial casting flow open, can better match the converter, ensure the casting speed of the continuous casting machine, reduce the number of tundishes, and improve the tundish turnover rate. This reduces refining power consumption, electrode consumption, gas consumption, and the temperature drop of molten steel throughout the process, enhances the operational stability of the steelmaking system, and has a significant energy-saving effect. In particular, it reduces the converter tapping temperature, saving energy consumption in the steelmaking process and ladle baking gas consumption.

[0038] In one embodiment, one of the two continuous casting machines operates with all ten casting streams open, while the other operates with only five casting streams open. That is, the two continuous casting machines operate in a "10-stream + 5-stream" production mode. By operating one continuous casting machine with only five casting streams open, better furnace-machine matching can be achieved, reducing the number of ladles and increasing ladle turnover.

[0039] In one embodiment, the converter is a 120-ton converter, and the total number of ladles ranges from 7 to 8. For a converter of the above specifications paired with a continuous casting machine, the required number of ladles is usually 10. In this application, the number of ladles is reduced to 7 or 8 through the above-mentioned settings. The reduction in the number of ladles can save on the consumption of ladle baking gas, which is beneficial to the stable control of molten steel and reduces the tapping temperature of the converter.

[0040] In one embodiment, the ladle turnover method of the continuous casting machine further includes: if a ladle is taken offline, a new ladle that meets the baking requirements is added to meet the total number of ladles. That is, a certain number of ladles are always maintained online, and when a ladle is taken offline due to lifespan issues, a new ladle that meets the baking requirements is immediately arranged from the ladle room to meet the ladle turnover needs.

[0041] In one embodiment, the total turnaround time is specifically the sum of the single-furnace casting cycle of the continuous casting machine, the smelting cycle of the corresponding refining furnace, the corresponding slag removal and hot repair time, the preparation cycle from the completion of the corresponding hot repair to the start of steel tapping in the converter, and the steel tapping cycle from the start of steel tapping in the converter to the start of smelting in the refining furnace. In the process of converter blowing – ladle refining – continuous casting, the converter, refining furnace, and continuous casting machine are respectively corresponding. Specifically, the ladle follows the turnaround process of “LD1→LF1→CC1→tuber hot repair→LD1 / LD2” and “LD2→LF2→CC2→tuber hot repair→LD1 / LD2”, where LD is oxygen top-blown converter steelmaking, LF is refining furnace refining, and CC is continuous casting machine casting. For ease of explanation, the two converters are respectively referred to as the first converter LD1 and the second converter LD2, and the two refining furnaces are referred to as the first converter LD1 and the second converter LD2. There is one refining furnace LF1 and two refining furnaces LF2, and two continuous casting machines denoted as the first continuous casting machine CC1 and the second continuous casting machine CC2. The ladles are rotated in the following manner: from the first converter LD1 to the first refining furnace LF1, then to the first continuous casting machine CC1, followed by hot nozzle repair, and then back to either the first converter LD1 or the second converter LD2; or from the second converter LD2 to the second refining furnace LF2, then to the second continuous casting machine CC2, followed by hot nozzle repair, and then back to either the first converter LD1 or the second converter LD2. To determine the number of ladles, the time required for each process is first determined as follows:

[0042] According to the production plan, the start-up requirements for the continuous casting machine were issued, and the single-furnace casting cycle T of the first continuous casting machine CC1 was determined. 11 The single-furnace casting cycle T of the second continuous casting machine CC2 21 ;

[0043] Based on the casting cycle of the continuous casting machine, the smelting requirements for the refining furnace were issued, and the smelting cycle T of the first refining furnace LF1 was determined. 12 The smelting cycle T of the second refining furnace LF2 22 ;

[0044] After the molten steel casting is completed, if the sprue slide plate is not replaced, determine the slag removal and hot repair time T. 13 When replacing the sprue slide plate, determine the slag removal and hot repair time T. 23 ;

[0045] Determine the period from hot repair of the taphole to preparation of the converter ladle before the start of converter steel tapping, i.e., the preparation period T1 from the completion of ladle hot repair to the start of converter steel tapping.

[0046] The steel charging cycle from the start of steel charging in the converter to the start of smelting in the refining furnace is determined. Since the first converter LD1 and the second converter LD2 have the same specifications, the steel charging cycle from the start of steel charging in the converter to the start of smelting in the refining furnace for both of them is the same, which is T2.

[0047] It should be noted that the specific time for each of the above processes can be determined through calculation or experimentation. Based on the determined times for each process, the ladle turnover quantity can be calculated. This can be done through the following steps:

[0048] Calculate the total turnaround time T of the ladle during casting on the first continuous casting machine CC1. 总1 ;

[0049] Calculate the total turnaround time T of the ladle during casting on the second continuous casting machine CC2. 总2 ;

[0050] Calculate the reasonable turnover quantity N1 of the ladle during casting on the first continuous casting machine CC1;

[0051] Calculate the reasonable turnover number N2 of the ladle during casting on the second continuous casting machine CC2;

[0052] Calculate the turnover quantity N when the first continuous casting machine CC1 and the second continuous casting machine CC2 are casting simultaneously. 总 =N² + N². Using the above method, the total number of steel ladles required for turnover can be determined simply and accurately.

[0053] In one embodiment, the slag removal and hot repair time specifically includes the slag removal and hot repair time for the nozzle slide plate replacement operation. That is, it is included in the calculation of the total turnaround time T. 总1 and total turnover time T 总2 At that time, the time for slag removal and hot repair, including the replacement of the sprue slide plate, is taken into account. 23 Calculations are performed to provide greater margin for ladle turnover. In other embodiments, the total turnover time can also be calculated based on the slag removal and hot repair time without replacing the nozzle slide plate, as needed.

[0054] In one embodiment, determining the number of ladles corresponding to the two continuous casting machines specifically includes: dividing the total turnaround time by the corresponding single-heat casting cycle and rounding up to obtain the number of ladles corresponding to the continuous casting machine. It can be understood that rounding up means adding 1 to the integer part of the total turnaround time divided by the corresponding single-heat casting cycle to obtain the number of ladles corresponding to the continuous casting machine. Using the rounding up method provides a larger margin for ladle turnaround, ensuring the reliability of ladle turnaround.

[0055] In one embodiment, the ladle turnover method for the continuous casting machine further includes: after slag removal and hot repair of the ladle, it is put into operation in either of the two converters. Please refer to [link to relevant documentation]. Figure 2 After the slag removal and hot repair of the ladle are completed, different converters can be supplied according to the production rhythm, which further improves the utilization rate of the ladle, thereby reducing the number of ladles and increasing the turnover rate of the ladle.

[0056] In one embodiment, after entering the converter, the ladle sequentially enters the corresponding refining furnace and continuous casting machine. That is, specialized production is adopted in the "converter (LD) - refining (LF) - continuous casting (CC)" process, with one converter supplying only one continuous casting machine. Therefore, the ladle follows the same flow in the "converter (LD) - refining (LF) - continuous casting (CC)" process: first converter LD1 - first refining furnace LF1 - first continuous casting machine CC1, and second converter LD2 - second refining furnace LF2 - second continuous casting machine CC2. After the ladle completes slag removal and hot repair, it can be supplied to either the first converter LD1 or the second converter LD2, depending on the production schedule.

[0057] To more clearly illustrate the ladle turnover method for continuous casting machines provided in this application, a specific embodiment will be used as an example below.

[0058] Taking Steel Plant A as an example, Steel Plant A currently has two 120t converters (i.e., the first converter LD1 and the first converter LD2), two 120t LF refining furnaces (the first refining furnace LF1 and the second refining furnace LF2), and two 10-strand small billet continuous casting machines (i.e., the first continuous casting machine CC1 and the second continuous casting machine CC2). The ladle follows the turnover process of "LD1→LF1→CC1→hot nozzle repair→LD1 / LD2" and "LD2→LF2→CC2→hot nozzle repair→LD1 / LD2".

[0059] According to the production plan, the continuous casting machine start-up requirements are issued. The first continuous casting machine CC1 will operate in a production mode of 10 casting flows, and the second continuous casting machine CC2 will operate in a production mode of 5 casting flows. Calculate the single-furnace casting cycle T of the first continuous casting machine CC1. 11 =30min, the single-furnace casting cycle T of the second continuous casting machine CC2 21 =45min;

[0060] Compared with the single-furnace casting cycle T of the first continuous casting machine CC1 11 and the single-furnace casting cycle T of the second continuous casting machine CC2 12 The refining requirements are issued, and the first refining furnace LF1 is connected to the first continuous casting machine CC1. The smelting cycle T of the first refining furnace LF1 is calculated. 12 =30min, second refining furnace LF2 → second continuous casting machine CC2, calculate the smelting cycle T of the second refining LF2. 22 =35min;

[0061] Calculate the slag removal and hot repair time T after the molten steel casting is completed and the sprue slide is not replaced. 13 =25min; Time T for slag removal and hot repair when changing the sprue slide plate 23 =30min;

[0062] Before the start of converter steel tapping, the period from hot repair of the tap nozzle to the preparation of the converter ladle, i.e. the preparation period from the completion of ladle hot repair to the start of converter steel tapping, is T1 = 5 minutes.

[0063] The steel charging cycle from the start of steel charging in the converter to the start of smelting in the refining furnace is the same for the first converter LD1 and the second converter LD2, which have the same specifications, and is T2 = 10min.

[0064] When the ladle nozzle of the first converter LD1 is undergoing hot repair and the nozzle slide plate is replaced, the ladle can be placed in the second converter LD2 after the repair is completed; when the ladle nozzle of the second converter LD2 is undergoing hot repair and the nozzle slide plate is replaced, the ladle can be placed in the first converter LD1 after the repair is completed.

[0065] Based on the above time and cycle, calculate the total turnaround time of the ladle during casting on the first continuous casting machine CC1, starting from the steel discharge from the first converter LD1 → the first refining furnace LF1 → the first continuous casting machine CC1 → hot repair of the nozzle → the first converter LD1 or the second converter LD2. This total turnaround time T 总1 =T 11 +T 12 +T 23 +T1+T2=105min.

[0066] Calculate the total turnaround time of the ladle during casting on the second continuous casting machine CC2, starting from the discharge of steel from the second converter LD2 → the second refining furnace LF2 → the second continuous casting machine CC2 → hot repair of the nozzle → the first converter LD1 or the second converter LD2. This total turnaround time T 总2 =T 21 +T 22 +T 23 +T1+T2=125min.

[0067] Calculate the reasonable turnover quantity N1 = T of the ladle during casting on the first continuous casting machine CC1. 总1 ÷T 11 =105 ÷ 30 = 3.5 = 4;

[0068] Calculate the reasonable turnover quantity of the ladle during casting on the second continuous casting machine CC2: N2 = T 总2 ÷T 21 =125÷45=2.78=3;

[0069] Calculate the turnover number N of ladles when casting simultaneously in the first continuous casting machine CC1 and the second continuous casting machine CC2. 总 =N1+N2=4+3=7; that is, two 10-strand small billet continuous casting machines simultaneously require a total of 7 steel ladles for turnover.

[0070] By applying this ladle turnover method, the consumption of refining electricity, electrode consumption, and gas consumption is effectively reduced, the temperature drop of molten steel throughout the process is reduced, the operational stability and safety factor of the steelmaking system are improved, and the energy-saving effect is significant, especially in reducing the converter tapping temperature and saving energy consumption in the steelmaking process and ladle baking gas consumption.

[0071] The present invention also provides a continuous casting production process, comprising the following steps:

[0072] Converter steelmaking;

[0073] Refined;

[0074] In continuous casting, the ladle turnover method of any of the continuous casting machines described in the above embodiments is used for ladle turnover.

[0075] By applying the continuous casting production process provided by this invention, one continuous casting machine can be operated with all the casting flow open, while another continuous casting machine is operated with only part of the casting flow open. This allows for better matching with the converter, ensuring the casting speed of the continuous casting machine, reducing the number of tundishes, and increasing the tundish turnover rate. Consequently, it reduces refining power consumption, electrode consumption, gas consumption, and the temperature drop of molten steel throughout the entire process. This enhances the operational stability of the steelmaking system and has a significant energy-saving effect, especially in reducing the converter tapping temperature and saving energy consumption in the steelmaking process and the gas consumption for ladle baking.

[0076] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0077] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A ladle turnover method for a continuous casting machine, used in a production line with two identical converters corresponding to two identical continuous casting machines, wherein the continuous casting machine has multiple crystallizers, corresponding to the simultaneous production of multiple casting streams, characterized in that... include: One of the two continuous casting machines is operated with all the casting flow open, while the other is operated with only part of the casting flow open. Based on the single-furnace casting cycle required for each of the two continuous casting machines and the total turnaround time of the ladle from the corresponding converter to the continuous casting machine, the number of ladles corresponding to each of the two continuous casting machines is determined, and the total number of ladles is obtained by summing them up. It also includes: after the ladle slag removal and hot repair are completed, it will be put into operation in either of the two converters; After the ladle enters the converter, it sequentially enters the refining furnace corresponding to the converter and the continuous casting machine. The single-furnace casting cycle of the continuous casting machine is the single-furnace casting cycle determined by the current number of castings. The total turnaround time is specifically the sum of the single-furnace casting cycle of the continuous casting machine, the smelting cycle of the corresponding refining furnace, the corresponding slag removal and hot repair time, the preparation cycle from the completion of the corresponding hot repair to the start of the converter steel discharge, and the steel discharge cycle from the start of the converter steel discharge to the start of the refining furnace smelting. The slag removal and hot repair time specifically includes the slag removal and hot repair time including the sprue slide plate replacement operation. One of the two continuous casting machines operates with all ten casting streams open, while the other operates with five casting streams open. The converter is a 120-ton converter, and the total number of ladles ranges from 7 to 8.

2. The ladle turnover method for a continuous casting machine according to claim 1, characterized in that, Also includes: If the ladle is produced, then additional ladles that meet the baking requirements are added to meet the total number of ladles.

3. The ladle turnover method for a continuous casting machine according to any one of claims 1-2, characterized in that, Determining the number of ladles corresponding to the two continuous casting machines respectively includes: The total turnaround time is divided by the corresponding single-furnace casting cycle and rounded up to obtain the number of ladles corresponding to the continuous casting machine.

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