Method for calculating erosion amount of continuous casting long nozzle

Abstract

The invention provides a method for calculating the erosion amount of a continuous casting long nozzle, which comprises the following steps: S1) adding ZrO2 in the preparation process of the long nozzle, and detecting the actual content of ZrO2; s2) adding BaO into a tundish covering agent, and detecting the actual content of BaO in the tundish covering agent; (S3) molten steel is poured, a tundish starts to pour a first furnace, and a certain amount of covering agent is added into an impact area of the tundish; the content of BaO and ZrO2 in tundish slag in a tundish impact area is detected in the last furnace of tundish pouring; s4) obtaining the weight of ZrO2 in the tundish slag according to the numerical values; and (S5) in the molten steel pouring process, the erosion and melting loss material of the long nozzle in the impact area enters the tundish slag, ZrO2 in the tundish slag is used for representing melting loss erosion of the long nozzle, and the melting loss erosion weight of the long nozzle is obtained. According to the calculation method, the melting loss erosion amount in the long nozzle pouring process can be accurately calculated and determined, and the erosion amount calibration and evaluation problem in the long nozzle steel pouring process is effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for calculating the erosion amount of a continuous casting shroud. Background Art

[0002] The shroud is an important refractory material in the continuous casting process. During the steel casting process, the molten steel is diverted from the large ladle to the medium ladle to avoid direct contact between the molten steel and the air and secondary oxidation. It is closely related to the continuous casting process and the cleanliness of the molten steel. However, during the casting process, the slag line area where the shroud contacts the slag in the medium ladle is constantly corroded and melted. When the erosion reaches a certain level, a new shroud needs to be replaced. Therefore, the melting erosion of the shroud becomes an important indicator for evaluating and optimizing the use of the shroud and its related medium ladle auxiliary materials (such as medium ladle covering agents).

[0003] Technicians have conducted relevant research on the erosion of the shroud. For example, the Chinese patent with publication number CN221289503U discloses a continuous casting shroud and continuous casting equipment, which can slow down the erosion of the tundish slag on the shroud, effectively increase the service life of the shroud, and save costs; the Chinese patent with publication number CN117226083A discloses a continuous casting shroud and a preparation method thereof, which can improve the thermal shock resistance and erosion resistance of the refractory parts of the shroud and extend its service life; the Chinese patent with publication number CN116967438A discloses a continuous casting ladle burst-resistant shroud, a slag line segment integrated with the shroud body is arranged above the shroud body, which can effectively improve the shroud's resistance to Burst performance; CN220612302U discloses a filtering continuous casting shroud, when the molten steel flows through the shroud body, the impurities in the molten steel are filtered to improve the surface quality of the ingot; Chinese patent with publication number CN220005977U discloses an argon-sealed shroud for a continuous casting tundish with a grid air channel, comprising a ladle water outlet and a shroud body, a grid air channel is provided in the contact area between the ladle water outlet and the shroud body, which can effectively reduce the air intake of the molten steel and avoid the dead zone formed by local air channel blockage during use; Chinese patent with publication number CN220028671U discloses a shroud for continuous casting, which has the effect of reducing the possibility of external air entering the molten steel.

[0004] The above patents mainly optimize the material, structure, and processing technology of the shroud to enhance the casting effect of the shroud, improve the stability of the casting process, and extend the service life. However, the existing patents do not have a calculation method for the erosion amount of the shroud during the steel casting process, making it difficult to provide accurate data support for the design optimization of the shroud and related tundish auxiliary materials. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a method for calculating the erosion amount of a continuous casting long nozzle. The calculation method provided by the present application can accurately calculate and determine the amount of melt loss erosion during the long nozzle casting process.

[0006] In view of this, the present application provides a method for calculating the erosion amount of a continuous casting shroud, comprising the following steps:

[0007] S1) Add ZrO2 during the preparation of the long nozzle, and detect the actual content of ZrO2 in the prepared long nozzle, which is recorded as w' Z , wt%;

[0008] S2) Adding BaO to the middle package covering agent, detecting the actual content of BaO in the middle package covering agent, recorded as w 1B , wt%;

[0009] S3) pouring molten steel, pouring the first heat of the tundish, adding covering agent to the impact zone of the tundish, the added amount is recorded as W1, kg;

[0010] After the last batch of tundish pouring, the BaO and ZrO2 contents of the tundish slag in the tundish impact zone were detected and recorded as w 2B 、w 2Z , wt%;

[0011] S4) Calculate the weight of BaO in the middle package covering agent, recorded as W 1BaO , W 1BaO =W1×w 1B ;

[0012] Calculate the ratio of ZrO2 to BaO in the tundish slag, denoted as R, R = w 2Z / w 2B The weight of ZrO2 in the tundish slag is recorded as W 2ZrO2 , W 2ZrO2 =W 1BaO ×R;

[0013] S5) During the pouring of molten steel, the molten material of the shroud is eroded in the impact zone into the tundish slag. The ZrO2 in the tundish slag is used to characterize the molten erosion of the shroud. The molten erosion weight of the shroud is recorded as W. 长水口侵蚀 , W 长水口侵蚀 =W 2ZrO2 / w' Z .

[0014] Preferably, in step S1), the weight of the prepared shroud is ≥100g.

[0015] Preferably, in step S1), the amount of ZrO2 added is 2-5wt% of the shroud.

[0016] Preferably, in step S2), the amount of BaO added is 2-4 wt%.

[0017] Preferably, in step S2), the weight of the middle package covering agent is detected to be ≥100 g.

[0018] Preferably, in step S3), the timing of adding the covering agent to the impact zone of the tundish is when the weight of the molten steel in the tundish reaches 40-60wt% of the nominal capacity.

[0019] Preferably, in step S3), the timing for detecting the BaO and ZrO2 contents in the tundish slag in the tundish impact zone is when the weight of the molten steel in the large ladle remains at 30-50wt%.

[0020] Preferably, in step S3), the detected weight of the middle ladle slag is ≥100g.

[0021] The present application also provides the application of the calculation method in the design of long shroud.

[0022] The present application provides a method for calculating the erosion amount of a continuous casting shroud, which comprises the following steps: first, adding ZrO2 during the preparation of the shroud, and detecting the actual content of ZrO2 in the shroud, and then adding BaO to the tundish covering agent, and detecting the actual content of BaO therein; then, pouring molten steel, starting the first furnace, and adding a covering agent of a specific weight to the tundish impact zone, and detecting the contents of BaO and ZrO2 in the tundish slag during the pouring of the last furnace; in the process of pouring steel, only the tundish covering agent contains BaO, and therefore, the mass of BaO in the impact zone during the pouring process is conserved, and based on this, the weight of ZrO2 in the tundish covering agent can be calculated; finally, all the ZrO2 in the tundish slag comes from the melt loss erosion of the shroud, and thus the shroud erosion weight is obtained. The calculation method of the erosion amount of the continuous casting shroud provided in the present application is based on the conservation of BaO mass in the impact zone during the pouring process and the melting erosion of ZrO2 in the tundish slag from the shroud. Therefore, the melting erosion amount of the shroud pouring process can be accurately calculated and determined, effectively solving the problem of calibration and evaluation of the erosion amount in the shroud steel pouring process. DETAILED DESCRIPTION

[0023] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0024] In view of the fact that there is no calibration calculation method for the erosion amount of the continuous casting long shroud in the steel pouring process in the prior art, this application provides a calculation method for the erosion amount of the continuous casting long shroud, which can accurately evaluate the erosion amount of the long shroud under different working conditions, and provide key data support for optimizing the design of the long shroud and its related tundish auxiliary materials, improving the erosion resistance of the long shroud, and improving the stability of the steel pouring process. Specifically, this application provides a calculation method for the erosion amount of the continuous casting long shroud, including the following steps:

[0025] S1) Add ZrO2 during the preparation of the long nozzle, and detect the actual content of ZrO2 in the prepared long nozzle, which is recorded as w' Z , wt%;

[0026] S2) Adding BaO to the middle package covering agent, detecting the actual content of BaO in the middle package covering agent, recorded as w 1B ;

[0027] S3) pouring molten steel, pouring the first heat of the tundish, adding covering agent to the impact zone of the tundish, the added amount is recorded as W1, kg;

[0028] After the last batch of tundish pouring, the BaO and ZrO2 contents of the tundish slag in the tundish impact zone were detected and recorded as w 2B 、w 2Z , wt%;

[0029] S4) Calculate the weight of BaO in the middle package covering agent, recorded as W 1BaO , W 1BaO =W1×w 1B ;

[0030] Calculate the ratio of ZrO2 to BaO in the tundish slag, denoted as R, R = w 2Z / w 2B The weight of ZrO2 in the tundish slag is recorded as W 2ZrO2 , W 2ZrO2 =W 1BaO ×R;

[0031] S5) During the pouring of molten steel, the molten material of the shroud is eroded in the impact zone into the tundish slag. The ZrO2 in the tundish slag is used to characterize the molten erosion of the shroud. The molten erosion weight of the shroud is recorded as W. 长水口侵蚀 , W 长水口侵蚀 =W 2ZrO2 / w' Z .

[0032] Specifically, ZrO2 is first added in the process of preparing the long water nozzle. Preferably, the added amount of ZrO2 is 2-5wt%. Specifically, the added amount of ZrO2 is 2wt%, 3wt%, 4wt%, and 5wt%. In addition, the preparation of the long water nozzle is based on methods and ingredients well known to those skilled in the art, and this application does not impose any special restrictions.

[0033] Before the shroud is put into use, some shroud samples are taken to test the actual content of ZrO2, which is recorded as w' Z , wt%; in order to ensure the accuracy of the detection, the amount of the long nozzle sample is ≥100g.

[0034] According to the present invention, BaO is added to the covering agent of the middle ladle, and BaO is used as a marker; the covering agent of the middle ladle includes components such as CaO, Al2O3, SiO2, and MgO, and the slag from the large ladle during the continuous casting process also contains the above substances, and the refractory material of the middle ladle also contains the above substances, so the weight of the above substances will change during the casting process; however, the slag from the large ladle and the refractory material of the middle ladle do not contain BaO, and BaO is added to the covering agent, and its mass remains unchanged during the casting process, so BaO can be used as a marker to calibrate the weight change of other components. In the present application, 2 to 4 wt% of BaO is added to the covering agent of the middle ladle, and specifically, the amount of BaO added can be 2wt%, 3wt% or 4wt%; if the amount of BaO added to the covering agent of the middle ladle is too little, the test result will have a large deviation, and if the amount added is too much, BaO may cause the performance of the covering agent of the middle ladle to change, affecting the smooth production process and the corrosion of the refractory material of the middle ladle. Afterwards, the middle ladle covering agent is selected to detect the actual content of BaO therein, which is recorded as w 1B For the accuracy of detection, the detection amount of the middle package covering agent is ≥100g.

[0035] The present application then pours the molten steel, and the tundish pours the first furnace. Preferably, when the weight of the molten steel in the tundish reaches 40-60% of the nominal capacity, a tundish covering agent is added to the tundish impact zone and other areas. The amount of the tundish covering agent added is W1, kg; then the amount of BaO added to the tundish covering agent is W 1BaO =W1×w 1B .

[0036] In the last batch of tundish pouring, preferably when the weight of the molten steel in the large ladle remains 30-50%, the tundish slag is taken out in the tundish impact zone and the contents of BaO and ZrO2 therein are detected and recorded as w 2B 、w 2Z , wt%; during the pouring process, when there is too little molten steel remaining in the large ladle, the temperature of the molten steel in the middle ladle is low, which may affect the slagging performance of the middle ladle slag in the impact zone of the middle ladle. The middle ladle slag may produce crusts, which makes it more difficult to take slag samples from the middle ladle slag, and the composition of the slag samples taken out has large deviations; when the amount of remaining steel in the large ladle is too high, the long nozzle is still eroded during the casting process of the remaining molten steel in the large ladle, resulting in the calculated erosion weight of the long nozzle being too small; in view of this, 30~50% was selected. At the same time, for the accuracy of the detection, the detection amount of the middle ladle slag is ≥100g. On this basis, the mass ratio of ZrO2 and BaO in the middle ladle slag is R=w 2Z / w 2B .

[0037] During the steel pouring process, except for the tundish covering agent, the tundish refractory materials and the slag under the large ladle in the impact zone do not contain BaO. Therefore, the mass of BaO in the impact zone during the casting process is conserved. Based on this, and further combined with the weight and proportion of BaO mentioned above, the mass of ZrO2 in the slag of the tundish in the impact zone of the last furnace, W, can be calculated.2ZrO2 =W 1BaO ×R; At the same time, during the steel pouring process, the molten material eroded by the shroud in the impact zone enters the tundish slag, and because a retaining wall is installed between the tundish impact zone and the casting zone, the tundish slag in the impact zone is blocked by the retaining wall and cannot flow into the casting zones on both sides of the tundish. Therefore, it can be considered that the ZrO2 in the tundish slag in the impact zone of the last furnace of the tundish comes entirely from the molten erosion of the shroud, and combined with the ZrO2 content of the shroud material w' Z Finally, the melting loss and erosion weight W of the long nozzle during the steel pouring process can be determined. 长水口侵蚀 =W 2ZrO2 / w' Z .

[0038] The present application also provides an application of the above calculation method in the design of a shroud. The calculation method provided in the present application can calculate the melting loss erosion weight of the shroud, and on this basis, the above calculation results can be used to provide a theoretical basis for the design and preparation of the shroud to increase the life of the shroud.

[0039] The present application provides a method for calculating the erosion amount of a long shroud in continuous casting. The method introduces the mass conservation marker BaO and performs calculations to obtain a method for calculating the erosion amount of a long shroud in continuous casting. The method can effectively solve the problem of calibrating and evaluating the erosion amount in the long shroud steel pouring process; and can accurately calculate and determine the amount of melt loss erosion in the long shroud steel pouring process.

[0040] In order to further understand the present invention, the calculation method of the erosion amount of the continuous casting long nozzle provided by the present invention is described in detail below in combination with embodiments, and the protection scope of the present invention is not limited by the following embodiments.

[0041] Example Calculation of erosion weight of the rear shroud of a two-strand slab continuous casting machine after continuous casting of 10 furnaces of IF steel

[0042] (1) When processing the long nozzle, 3% ZrO2 is added to the material;

[0043] (2) Before the shroud is put into use, take 150g of shroud material sample and test and analyze its actual ZrO2 content w' Z =3.12%;

[0044] (3) Mix 2% BaO in the middle package covering agent, and take 150g of the mixed middle package covering agent to detect and analyze its actual BaO content w 1B =1.92%;

[0045] (4) When pouring steel, the first heat of the tundish is poured. When the weight of the molten steel in the tundish reaches 60% of the nominal capacity, a certain amount of covering agent is added to the impact zone and other areas of the tundish. The weight of the covering agent added to the impact zone is W1 = 400 kg.

[0046] (5) In the last batch of tundish casting, when the weight of the molten steel in the large ladle remains at 30%, 150 g of tundish slag (formed by melting the added tundish covering agent) is taken from the tundish impact zone and the contents of BaO and ZrO2 in the tundish slag are tested, which are w 2B =1.31%, w 2Z =0.23%;

[0047] (6) Calculate the weight of BaO added to the impact zone of the tundish, recorded as W 1BaO , W 1BaO =W1×w 1B =400×1.92%=7.68kg;

[0048] (7) Calculate the ratio of ZrO2 to BaO in the slag of the last batch of tundish casting (R = w) 2Z / w 2B =0.23% / 1.31%=0.176;

[0049] (8) During the steel casting process, except for the covering agent, the middle ladle refractory and the ladle slag in the impact zone do not contain BaO. Therefore, the mass of BaO in the impact zone during the casting process is conserved. Based on this, further combined with steps (6) and (7), the mass of ZrO2 in the middle ladle slag in the impact zone of the last furnace can be calculated and determined as: 2ZrO2 =W 1BaO ×R=7.68kg×0.176=1.35kg;

[0050] (9) During the steel pouring process, the molten material eroded by the shroud in the impact zone enters the tundish slag. Since a retaining wall is installed between the impact zone and the casting zone of the tundish, the slag in the impact zone is blocked by the retaining wall and cannot flow into the casting zones on both sides of the tundish. Therefore, it can be considered that the ZrO2 in the tundish slag in the impact zone of the last furnace of the tundish comes entirely from the molten erosion of the shroud, and combined with the ZrO2 content w' in the shroud material Z Finally, the melting loss and erosion weight W of the long nozzle during the steel pouring process can be determined. 长水口侵蚀 =W 2ZrO2 / w' Z =1.35kg / 3.12%=43.2kg.

[0051] In order to verify the accuracy of the calculation results, in this embodiment, the weight of the long water nozzle was weighed as 175.1 kg before it was used on the line. After the long water nozzle was used off the line, its weight was weighed again as 130.7 kg. The actual erosion weight of the long water nozzle during the casting process was 44.4 kg. The calculated value of 43.2 kg provided in this application is consistent with the measured value of 44.4 kg, which proves the reliability of the calculation method of this application.

[0052] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0053] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one 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 present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for calculating the erosion amount of a continuous casting shroud, comprising the following steps: S1) Add ZrO2 during the preparation of the long nozzle, and detect the actual content of ZrO2 in the prepared long nozzle, which is recorded as w' Z , wt%; S2) Adding BaO to the middle package covering agent, detecting the actual content of BaO in the middle package covering agent, recorded as w 1B , wt%; S3) pouring molten steel, pouring the first heat of the tundish, adding covering agent to the impact zone of the tundish, the added amount is recorded as W1, kg; After the last batch of tundish pouring, the BaO and ZrO2 contents of the tundish slag in the tundish impact zone were detected and recorded as w 2B 、w 2Z , wt%; S4) Calculate the weight of BaO in the middle package covering agent, recorded as W 1BaO , W 1BaO =W1×w 1B ; Calculate the ratio of ZrO2 to BaO in the tundish slag, denoted as R, R = w 2Z / w 2B The weight of ZrO2 in the tundish slag is recorded as W 2ZrO2 , W 2ZrO2 =W 1BaO ×R; S5) During the pouring of molten steel, the molten material of the shroud is eroded in the impact zone into the tundish slag. The ZrO2 in the tundish slag is used to characterize the molten erosion of the shroud. The molten erosion weight of the shroud is recorded as W. 长水口侵蚀 , W 长水口侵蚀 =W 2ZrO2 / w' Z .

2. The calculation method according to claim 1, characterized in that: In step S1), the weight of the prepared shroud is ≥100g.

3. The calculation method according to claim 1, characterized in that: In step S1), the amount of ZrO2 added is 2-5wt% of the shroud.

4. The calculation method according to claim 1, characterized in that: In step S2), the amount of BaO added is 2-4 wt%.

5. The calculation method according to claim 1, characterized in that: In step S2), the weight of the middle package covering agent is detected to be ≥ 100 g.

6. The calculation method according to claim 1, characterized in that: In step S3), the timing for adding the covering agent to the impact zone of the tundish is when the weight of the molten steel in the tundish reaches 40-60wt% of the nominal capacity.

7. The calculation method according to claim 1, characterized in that: In step S3), the timing for detecting the BaO and ZrO2 contents in the tundish slag in the tundish impact zone is when the weight of the molten steel in the large ladle remains at 30-50wt%.

8. The calculation method according to claim 1, characterized in that: In step S3), the detected weight of the tundish slag is ≥100g.

9. Application of the calculation method according to any one of claims 1 to 8 in shroud design.