Method for calculating erosion amount of tundish stopper rod in continuous casting process and application

Abstract

The invention provides a method for calculating the erosion amount of a tundish stopper rod in the continuous casting process, which comprises the following steps: S1) adding ZrO2 in the stopper rod preparation process, and detecting the actual content of ZrO2 in the stopper rod; detecting the content of CaO in the tundish covering agent; s2) during steel casting, a tundish starts to cast a first furnace, and a certain amount of tundish covering agent is added into a tundish casting area; the tundish is cast to the last furnace, and the content of CaO and ZrO2 in tundish slag is detected; s3) calculating the weight of CaO in the tundish covering agent and the content ratio of ZrO2 to CaO in the tundish slag; the weight of ZrO2 in the tundish slag is obtained; and S4) representing the melting loss erosion amount of the stopper rod by the weight of ZrO2 in the tundish slag to obtain the melting loss erosion weight of the stopper rod in the steel casting process. According to the calculation method provided by the invention, the erosion amount of the stopper rod under different working conditions can be accurately calculated and evaluated, and a key data support is provided for optimizing the material, the structure and the processing technology of the stopper rod and finally improving the erosion resistance of the stopper rod.

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 stopper rod in a continuous casting process and its application. Background Art

[0002] The stopper rod is a key component of the continuous casting tundish, and is known as the "three major parts of continuous casting" together with the long nozzle and the submerged nozzle. In the continuous casting process, the stopper rod mainly plays the role of controlling the flow and adjusting the steel pouring speed. During the steel pouring process, the stopper rod is constantly eroded by melting in the slag line area where it contacts the tundish slag. On the one hand, it affects the service life of the stopper rod. On the other hand, the eroded stopper rod becomes an important factor affecting the cleanliness of the molten steel. Therefore, how to slow down the erosion of the stopper rod and extend its service life has become an important direction for improving the quality and reducing the cost of continuous casting.

[0003] Chinese patent with publication number CN117862438A discloses a process control method for producing rare earth steel, which adopts rare earth functional refractory materials to solve the problems of rare earth elements in steel corroding functional refractory materials such as continuous casting nozzles and stopper rods during rare earth steel casting, resulting in rare earth burning, rare earth yield fluctuations, and continuous casting flow control failure. Chinese patent with publication number CN117430413A discloses a stopper rod for continuous casting and a preparation method thereof. The stopper rod body is made of aluminum-magnesium-carbon or magnesium-carbon, and the rod head is made of aluminum-magnesium-carbon or magnesium-carbon, which can effectively improve the thermal shock resistance and spalling resistance of the stopper rod and extend the service life of the stopper rod. Chinese patent with publication number CN114769574A discloses a method for improving the service life of an integral stopper rod for continuous casting, by arranging a conductive material resistant to high temperature and erosion by molten steel in the tundish as an anode, and connecting it to the integral stopper rod with a wire, and the integral stopper rod is used as a cathode, thereby improving the corrosion resistance of the material. Improve the service life of the whole stopper rod; Chinese patent with publication number CN216989847U discloses three continuous casting parts for high oxygen enameled steel, which can effectively improve the thermal stability and corrosion resistance of the three continuous casting parts; Chinese patent with publication number CN114292117A discloses a three continuous casting part for high performance steel in a middle package, which uses fused magnesium aluminum spinel (MgO·Al2O3) as the three material, thereby improving the three parts' ability to resist corrosion by molten steel and slag under high temperature, which helps to extend the service life, reduce impurities, and reduce production costs; Chinese patent with publication number CN112775423A discloses a combined integral composite stopper rod and a preparation method thereof, the combined integral composite stopper rod comprises a rod head, a transition section, a rod body and an inner cavity arranged at the inner axis of the rod body, the outer circumferential wall of the rod body is provided with a slag line reinforcement sleeve, the slag line reinforcement sleeve is embedded in the outer wall of the rod body through fire mud, and effectively avoids the erosion of the covering agent on the slag line part of the stopper rod body.

[0004] In summary, the existing patents currently propose improvement methods mainly from the aspects of stopper rod material, structure, processing technology, etc., in order to enhance the anti-corrosion performance of the stopper rod and extend its service life. However, the above patents do not propose a method for accurately and quantitatively calculating and evaluating the amount of stopper rod erosion during the steel pouring process, making it difficult to provide accurate data support for the effect of stopper rod optimization. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a method for calculating the erosion amount of the tundish stopper rod in the continuous casting process. The calculation method provided in the present application can accurately calculate and evaluate the erosion amount of the stopper rod under different working conditions.

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

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

[0008] Detect the CaO content in the middle package covering agent, denoted as w 1C , wt%;

[0009] S2) When pouring steel, the tundish is opened to pour the first furnace, and a tundish covering agent is added to the tundish casting area, and the added weight of the tundish covering agent is recorded as W1, kg;

[0010] After the tundish casting reaches the last furnace, the CaO and ZrO2 contents in the tundish slag in the tundish casting area are detected and recorded as w 2C 、w 2Z , wt%;

[0011] S3) Calculate the weight of CaO in the coating agent, recorded as W 1CaO , W 1CaO =W1×w 1C ;

[0012] Calculate the content ratio of ZrO2 and CaO in the tundish slag, R = w 2Z / w 2C ;

[0013] According to the mass conservation of CaO in the tundish covering agent, calculate the weight W of ZrO2 in the tundish slag 2ZrO2 =W 1CaO ×R;

[0014] S4) The weight of ZrO2 in the tundish slag is used to characterize the melting loss and erosion of the stopper rod, and the melting loss and erosion weight W of the stopper rod during the steel pouring process is obtained. 塞棒侵蚀 =W 2ZrO2 / w' Z .

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

[0016] Preferably, in step S1), the sampling of the stopper rod for detecting the actual content of ZrO2 in the stopper rod is ≥ 100 g.

[0017] Preferably, in step S1), the middle package covering agent does not contain ZrO2.

[0018] Preferably, in step S1), when detecting the content of CaO in the middle-package covering agent, the sampling amount of the middle-package covering agent is ≥ 100 g.

[0019] Preferably, in step S2), the timing of adding the tundish covering agent is when the weight of the molten steel in the tundish reaches 40-60% of the nominal capacity.

[0020] Preferably, in step S2), the timing for detecting the content of CaO and ZrO2 in the tundish slag in the tundish casting area is when 30-50% of the weight of the molten steel in the ladle remains.

[0021] Preferably, in step S2), the sampling of the tundish slag for detecting the CaO and ZrO2 contents in the tundish slag in the tundish casting area is ≥100g.

[0022] The present application also provides the application of the calculation method in stopper rod design.

[0023] The present application provides a method for calculating the erosion amount of a tundish stopper rod in a continuous casting process, which firstly adds ZrO2 during the preparation of the stopper rod, and detects the actual content of ZrO2 in the stopper rod, and detects the content of CaO in the tundish covering agent; then, steel is poured, the first furnace is poured in the tundish, a tundish covering agent is added to the tundish casting area, and the added weight is marked, and the CaO and ZrO2 in the tundish slag in the tundish casting area are detected after the tundish casting reaches the last furnace, and on the basis of the above, the weight of CaO in the tundish covering agent, and the contents of ZrO2 and CaO in the tundish slag are calculated. ratio, and according to the mass conservation of CaO in the tundish covering agent, the weight of ZrO2 in the tundish slag is obtained, and finally the weight of ZrO2 in the tundish slag is used to characterize the melting loss erosion of the stopper rod, and the melting loss erosion weight of the stopper rod in the steel pouring process is obtained; in the calculation method of the erosion amount of the tundish stopper rod in the continuous casting process provided in the present application, by taking CaO as a marker and the mass conservation of CaO in the tundish covering agent, the erosion amount of the stopper rod in the steel pouring process can be accurately calculated and evaluated, which can provide key support for optimizing the material, structure and processing technology of the stopper rod, and ultimately improving the erosion resistance of the stopper rod. DETAILED DESCRIPTION

[0024] 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.

[0025] In view of the lack of a quantitative calibration calculation method for the erosion amount of the intermediate ladle stopper rod in the continuous casting process in the prior art, the present application provides a calculation and evaluation method for the erosion amount of the intermediate ladle stopper rod in the continuous casting process, which can effectively solve the current research deficiencies and fill the research gap in the accurate calibration calculation method of the stopper rod erosion amount. The present application can accurately calculate and evaluate the degree of stopper rod erosion based on the process parameters related to the change of the ladle slag composition during the casting process of the tundish, and provide key data support for optimizing related processes without affecting normal production. Specifically, an embodiment of the present invention discloses a calculation method for the erosion amount of the intermediate ladle stopper rod in the continuous casting process, comprising the following steps:

[0026] S1) Add ZrO2 during the preparation of the stopper rod, and detect the actual content of ZrO2 in the stopper rod, which is recorded as w' Z , wt%;

[0027] Detect the CaO content in the middle package covering agent, denoted as w 1C , wt%;

[0028] S2) When pouring steel, the tundish is opened to pour the first furnace, and a tundish covering agent is added to the tundish casting area, and the added weight of the tundish covering agent is recorded as W1, kg;

[0029] After the tundish casting reaches the last furnace, the CaO and ZrO2 contents in the tundish slag in the tundish casting area are detected and recorded as w 2C 、w 2Z , wt%;

[0030] S3) Calculate the weight of CaO in the coating agent, recorded as W 1CaO , W 1CaO =W1×w 1C ;

[0031] Calculate the content ratio of ZrO2 and CaO in the tundish slag, R = w 2Z / w 2C ;

[0032] According to the mass conservation of CaO in the tundish covering agent, calculate the weight W of ZrO2 in the tundish slag 2ZrO2 =W 1CaO ×R;

[0033] S4) The weight of ZrO2 in the tundish slag is used to characterize the melting loss and erosion of the stopper rod, and the melting loss and erosion weight W of the stopper rod during the steel pouring process is obtained. 塞棒侵蚀 =W 2ZrO2 / w' Z .

[0034] In the method for calculating the erosion amount of the intermediate package stopper rod during the continuous casting process, the present application first adds ZrO2 during the preparation of the stopper rod, and the amount of ZrO2 added is 2-5wt% of the total mass of the stopper rod. Specifically, the amount of ZrO2 added is 2wt%, 3wt%, 4wt% or 5wt% of the stopper rod; in addition, the preparation method of the stopper rod is prepared according to the method well known to those skilled in the art. Before the stopper rod is put into use, the actual content of ZrO2 in the stopper rod is detected and recorded as w' Z , wt%; in the process of detecting the actual content of ZrO2, the stopper rod sample weighing ≥100g is used.

[0035] According to the present invention, the content of CaO in the mid-bag covering agent is detected. In this process, the mid-bag covering agent preferably uses a mid-bag covering agent sample of ≥100g; in addition, the other components in the mid-bag covering agent are components well known to those skilled in the art, and this application does not impose any special restrictions on this. CaO is one of the main components in the covering agent, and its content is relatively high, and it is very easy to accurately detect and determine; importantly, during the mid-bag casting process, since the refractory material in the mid-bag casting area does not contain CaO, the CaO in the covering agent can be considered to be conserved in mass. Therefore, in this application, CaO is used as a marker, and the weight of other components can be finally determined by detecting the content of other components and the content of CaO in the covering agent during the mid-bag casting process, and then according to the ratio of the content of other components to the content of CaO.

[0036] In the process of pouring steel, the first furnace is poured in the tundish. Preferably, when the weight of the molten steel in the tundish reaches 40-60wt% of the nominal capacity, the above-mentioned tundish covering agent is added to the tundish casting area and other areas. The weight of the tundish covering agent added to the casting area is recorded as W1, kg. When the tundish is cast to the last furnace, the CaO and ZrO2 contents in the tundish slag (formed by the melting of the tundish covering agent) in the tundish casting area are detected and recorded as w 2C 、w 2Z , wt%; During the casting process, when the remaining molten steel in the large ladle is too little, the temperature of the molten steel in the tundish is low, which may affect the slag-forming performance of the slag in the tundish impact zone, and the slag in the tundish may form a crust, which makes it more difficult to take slag samples from the tundish slag, and the composition of the slag samples taken out is large. When the remaining steel in the large ladle is too high, the shroud is still eroded during the casting of the remaining molten steel in the large ladle, resulting in a small calculated erosion weight of the shroud. In view of this, the detection time of CaO and ZrO2 in the tundish slag is selected when the weight of the molten steel in the large ladle is 30-50%.

[0037] Based on the content and weight detected above, the weight of CaO in the coating agent is calculated and recorded as W 1CaO , W 1CaO =W1×w 1C ; Calculate the content ratio of ZrO2 and CaO in the tundish slag, R = w2Z / w 2C .

[0038] Since a retaining wall is usually installed between the tundish casting area and the impact area, it can effectively block the slag (containing CaO) from the ladle from flowing to the casting area. At the same time, the refractory in the casting area does not contain CaO. Therefore, it can be considered that the mass of CaO in the tundish covering agent added to the casting area is conserved. Based on this, the weight of ZrO2 in the tundish slag in the casting area when the tundish is cast for the last batch can be quantitatively calculated. 2ZrO2 =W 1CaO ×R. Furthermore, since the tundish covering agent usually does not contain ZrO2, it can be considered that the weight of ZrO2 in the tundish slag of the last batch of tundish is W 2ZrO2 All of them come from the melting erosion of the stopper rod, combined with the ZrO2 content w' of the stopper rod material Z Finally, the melting loss and erosion weight W of the stopper rod during the steel pouring process can be determined. 塞棒侵蚀 =W 2ZrO2 / w'Z.

[0039] The present application also provides the application of the above calculation method in stopper rod design; in the present application, the stopper rod design may be the design of the stopper rod material, the design of the stopper rod size, etc., and the present application does not impose any particular limitation on this.

[0040] The present invention provides a method for calculating and evaluating the erosion amount of the middle ladle stopper rod in the continuous casting process. The method can accurately calculate and evaluate the erosion amount of the stopper rod under different working conditions, and provide key data support for optimizing the material, structure and processing technology of the stopper rod, and ultimately improving the erosion resistance of the stopper rod. The method can provide data support for optimizing the stopper rod and improving its erosion resistance, thereby reducing the consumable cost of the middle ladle steel stopper rod, and at the same time help to improve the cleanliness of molten steel and reduce the loss caused by inclusion defects. It is estimated that the annual profit will be at least 500,000 yuan.

[0041] In order to further understand the present invention, the calculation method of the erosion amount of the intermediate plug rod in the continuous casting process provided by the present invention is described in detail below in conjunction with embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0042] Example Calculation of erosion weight of plug rod in two-stream 70-ton tundish for continuous casting of 10 furnaces of ultra-low carbon steel

[0043] (1) When the stopper rod is processed and manufactured, 4% ZrO2 is added to the material;

[0044] (2) Before the stopper rod is put into use, take a 100g stopper rod material sample and test and analyze its ZrO2 content w' Z =4.3%;

[0045] (3) Take 150g of the middle package covering agent before use and test and analyze its CaO content w 1C =30.75%;

[0046] (4) When pouring steel, the first heat is poured from the tundish. 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 casting area and other areas of the tundish. The weight of the covering agent added to the casting area is W1 = 160 kg.

[0047] (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 casting area to test the CaO and ZrO2 contents of the tundish slag, which are recorded as w 2C 、w 2Z , where w 2C =23.17%, w 2Z =0.21%;

[0048] (6) Calculate the weight of CaO covering agent before use, recorded as W 1CaO , then W 1CaO =W1×w 1M =160kg×30.75%=49.2kg;

[0049] (7) Calculate the ratio of ZrO2 to CaO in the slag of the last batch of tundish casting (R = w) 2Z / w 2C =0.21% / 23.17%=0.009;

[0050] (8) Since a retaining wall is usually installed between the tundish casting area and the impact area, it can effectively prevent the slag (containing CaO) from the ladle from flowing to the casting area. At the same time, the refractory in the casting area does not contain CaO. Therefore, it can be considered that the mass of CaO in the tundish covering agent added to the casting area is conserved. Based on this, the weight of ZrO2 in the tundish slag in the casting area when the tundish is cast for the last batch can be quantitatively calculated. 2ZrO2 =W 1CaO ×R=49.2kg×0.009=0.443kg;

[0051] (9) Since the tundish covering agent usually does not contain ZrO2, the weight of ZrO2 in the tundish slag of the last batch of tundish can be considered to be W 2ZrO2 All of them come from the melting erosion of the stopper rod, combined with the ZrO2 content w' of the stopper rod material Z Finally, the melting loss and erosion weight W of the stopper rod during the steel pouring process can be determined. 塞棒侵蚀 =W 2ZrO2 / w' Z =0.443kg / 4.3%=10.3kg.

[0052] In order to verify the accuracy of the method of this patent, in the example, before the stopper rod was put into use, the weight of the stopper rod was weighed to be 74.5kg. After the tundish was cast, the weight of the stopper rod was weighed again to be 64.3kg. That is, the actual erosion weight of the stopper rod was 74.5kg-64.3kg=10.2kg. The calculation result of 10.3kg provided by the method of this application is consistent with the actual erosion weight of 10.2kg, which proves the accuracy of the calculation method of this patent.

[0053] 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.

[0054] 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 the intermediate plug rod in the continuous casting process, comprising the following steps: S1) Add ZrO2 during the preparation of the stopper rod, and detect the actual content of ZrO2 in the stopper rod, which is recorded as w' Z , wt%; Detect the CaO content in the middle package covering agent, denoted as w 1C , wt%; S2) When pouring steel, the tundish is opened to pour the first furnace, and a tundish covering agent is added to the tundish casting area, and the added weight of the tundish covering agent is recorded as W1, kg; After the tundish casting reaches the last furnace, the CaO and ZrO2 contents in the tundish slag in the tundish casting area are detected and recorded as w 2C 、w 2Z , wt%; S3) Calculate the weight of CaO in the coating agent, recorded as W 1CaO , W 1CaO =W1×w 1C ; Calculate the content ratio of ZrO2 and CaO in the tundish slag, R = w 2Z / w 2C ; According to the mass conservation of CaO in the tundish covering agent, calculate the weight W of ZrO2 in the tundish slag 2ZrO2 =W 1CaO ×R; S4) The weight of ZrO2 in the tundish slag is used to characterize the melting loss and erosion of the stopper rod, and the melting loss and erosion weight W of the stopper rod during the steel pouring process is obtained. 塞棒侵蚀 =W 2ZrO2 / w' Z .

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

3. The calculation method according to claim 1, characterized in that: In step S1), the actual content of ZrO2 in the stopper rod is detected by sampling ≥ 100 g of the stopper rod.

4. The calculation method according to claim 1, characterized in that: In step S1), the middle package covering agent does not contain ZrO2.

5. The calculation method according to claim 1, characterized in that: In step S1), the content of CaO in the middle package covering agent is detected, and the sampling of the middle package covering agent is ≥ 100g.

6. The calculation method according to claim 1, characterized in that: In step S2), the timing of adding the tundish covering agent is when the weight of the molten steel in the tundish reaches 40-60% of the nominal capacity.

7. The calculation method according to claim 1, characterized in that: In step S2), the timing for detecting the content of CaO and ZrO2 in the tundish slag in the tundish casting area is when 30-50% of the weight of the molten steel in the ladle remains.

8. The calculation method according to claim 1, characterized in that: In step S2), the sampling of the tundish slag in the tundish casting area for detecting the CaO and ZrO2 contents in the tundish slag is ≥100g.

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