Method for reducing cinder shell on the ladle nozzle with a cover

Abstract

The application discloses a method for reducing slag shell on a ladle opening with a cover and belongs to the technical field of metallurgy. The method comprises the following steps: dividing a cross section of the ladle opening with the cover into four equal parts, marking 3 o'clock, 6 o'clock, 9 o'clock and 12 o'clock positions according to a clock scale, setting a circumference section from 3 o'clock to 6 o'clock to 9 o'clock as a backward steel / slag section, adding rice hull insulation agent to the center of the ladle when calcium wire feeding is completed and a soft blowing stage is entered, spreading the carbonized rice hull evenly and rapidly under the soft blowing state, starting the ladle car in the direction of the line connecting 6 o'clock and 12 o'clock before and after the end of the soft blowing, making the liquid surface of 6 o'clock and 12 o'clock higher or lower than the normal level of the liquid surface by using the swing force, and promoting the slag shell on the circumference section from 3 o'clock to 12 o'clock to 9 o'clock to fall off. The above method can reduce the number of slag shells on the ladle opening with the cover by reasonably utilizing the swing force of the ladle car, using common materials and distributing the carbonized rice hull at specific positions, and can greatly reduce the number of slag shells on the non-backward steel and slag positions.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and more specifically, to a method for reducing slag crust formation at the mouth of a covered steel ladle. Background Technology

[0002] In the steel industry, covering ladles plays a crucial role in reducing the temperature drop of the ladle and molten steel, and decreasing the consumption of baking gas. To save energy and reduce emissions, covered ladles are becoming increasingly widely used. However, because ladles are placed horizontally in hot repair stations, their covers cannot be easily removed. Once slag builds up at the ladle opening, especially in areas not directly connected to the slag, the small opening angle of the ladle cover makes cleaning difficult and ineffective. Current methods for reducing slag buildup at the ladle opening include: 1. Direct removal, which is time-consuming and labor-intensive, although efficiency can be improved with certain techniques (CN113523256A - A method and device for rapidly improving the cleanliness of covered ladles); 2. Adding slag-reducing agents to alter the viscosity and other properties of the slag, but this introduces new materials that are difficult to manage and increase costs. Therefore, a quick and effective solution to reduce slag buildup at the ladle opening of covered ladles is urgently needed.

[0003] Therefore, this invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art and provide a method for reducing slag buildup at the mouth of a covered ladle.

[0005] The technical problem solved by this invention is achieved by the following technical solution.

[0006] This invention provides a method for reducing slag crust formation at the mouth of a covered steel ladle, comprising: dividing the cross-section of the covered steel ladle mouth into four equal parts, marking the positions of 3 o'clock, 6 o'clock, 9 o'clock, and 12 o'clock according to a clock scale, and designating the circumferential section from 3 o'clock to 6 o'clock to 9 o'clock as the steel / slag pouring section; when the molten steel has finished feeding the calcium wire and entered the soft blowing stage, adding rice husk heat-insulating agent to the center of the ladle; in the soft blowing state, making the carbonized rice husk spread quickly and evenly; and before and after the soft blowing ends, starting the ladle car in the direction of the line connecting 6 o'clock and 12 o'clock, using the swaying force to make the slag liquid level at 6 o'clock and 12 o'clock higher or lower than the normal liquid level, causing the slag crust on the ladle wall of the circumferential section from 3 o'clock to 12 o'clock to 9 o'clock to fall off.

[0007] The present invention has the following beneficial effects:

[0008] This invention provides a method for reducing slag crust formation at the mouth of a covered steel ladle. The method involves operating the ladle car, making reasonable use of the sloshing motion of molten steel, and using commonly used materials to carbonize rice husks. The carbonized rice husks are then placed at specific locations to reduce the amount of slag crust formation at the mouth of the covered steel ladle, particularly significantly reducing the amount of slag crust formation in the non-slag / steel-pouring sections of the covered ladle. This invention's solution is simple and effective, and can quickly reduce the amount and probability of slag crust formation at the mouth of a covered steel ladle. Attached Figure Description

[0009] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 A schematic diagram showing the cross-section of a covered steel bag, divided and marked according to clock scales;

[0011] Figure 2 A photo of the slag crust at the mouth of a covered steel ladle before the technical upgrade;

[0012] Figure 3 This is a photograph of the slag crust at the ladle opening after the technical upgrade (Example 1).

[0013] Figure 4 This is a photograph of the slag crust formed at the ladle opening after treatment in Comparative Example 1.

[0014] Figure 5 This is a photograph of the slag crust formed at the ladle opening after treatment in Comparative Example 2;

[0015] Figure 6 This is a photograph of the slag crust at the ladle opening after treatment in Comparative Example 3.

[0016] Figure 7 This is a photograph of the slag crust formed at the ladle opening after treatment in Comparative Example 4. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0018] The following is a detailed description of a method for reducing slag buildup at the mouth of a covered steel ladle, provided by an embodiment of the present invention.

[0019] This invention provides a method for reducing slag buildup at the mouth of a covered steel ladle, employing at least one of the following measures:

[0020] See Figure 1 For ease of explanation, the cross-section of the covered steel ladle opening is divided into 4 equal parts, and the positions of 3 o'clock, 6 o'clock, 9 o'clock and 12 o'clock are marked according to the clock scale. The circumferential segment from 3 o'clock to 6 o'clock to 9 o'clock is defined as the steel / slag pouring segment (and the steel / slag pouring segment is defined as the front segment, and the non-steel / slag pouring segment is defined as the back segment).

[0021] 1. After the molten steel has been fed with calcium wire during normal processing and enters the soft blowing stage, add one bag of carbonized rice husks (approximately 7-8 kg / bag) to each of the centers of the lines connecting the 0 point to the 3, 6, 9, and 12 points on the ladle (i.e., the center of the ladle radius) (totaling 4 bags). Simultaneously, control the bottom blowing air flow rate of the ladle to 5-10 Nm. 3 / h, to ensure the carbonized rice husks are spread out quickly and evenly. After 5 minutes of soft blowing, drive the ladle car to the carbonized rice husk distribution position, while simultaneously reducing the bottom blowing air flow rate of the ladle to 0-5Nm. 3 / h.

[0022] 2. After continuing soft blowing (N-5) / 2min (where N is the minimum soft blowing time required for this furnace, and N is generally ≥10min), start moving the ladle car back and forth to make the slag interface sway back and forth. Use the swaying force to make the slag liquid level at 6 o'clock and 12 o'clock periodically higher or lower than the normal liquid level by 0-200mm. At the same time, along the slag interface of the ladle wall, start spreading carbonized rice husks with a rotating chute from 3 o'clock to 12 o'clock to 9 o'clock (or 9 o'clock to 12 o'clock to 3 o'clock) to ensure that the weight of carbonized rice husks spread per unit length (on the semicircle) is 5-10kg (i.e., 5-10kg / m), the spreading width is 50-150mm, and the total spreading time is ≤2min. After spreading, stop moving the ladle car and let the slag liquid level return to calm automatically (to avoid sintering of slag and refractory bricks).

[0023] 3. After stopping the feeding (N-5) / 4min, start the ladle car back and forth once, using the swaying force to make the slag liquid level at 6 o'clock and 12 o'clock 0-200mm higher or lower than the normal level. Immediately stop starting the ladle car, and then let the slag liquid level return to calm automatically (to avoid sintering of slag and refractory bricks).

[0024] 4. After the molten steel is soft-blown and covered, start the ladle car back and forth once more. Use the swaying motion to make the slag level at 6 o'clock and 12 o'clock 0-200mm higher or lower than the normal level. Immediately stop starting the ladle car and allow the slag level to return to calm automatically. The molten steel is then lifted by the overhead crane to the continuous casting ladle turntable for pouring (to prevent the slag from sintering with the refractory bricks).

[0025] 5. Ensure that the interval between the molten steel in the ladle being lifted by the overhead crane and just before it is poured on the rotary table is ≤8 minutes (to avoid sintering of steel slag and refractory bricks).

[0026] 6. During the pouring of molten steel, the rate at which the molten steel level drops must be ≥75mm / min (to reduce the time that steel slag remains at the same height and to prevent the steel slag from sintering with the refractory bricks).

[0027] 7. Preferably, it is also necessary to identify whether the equipment for removing slag shells from the ladle mouth (such as a slag removal vehicle) is at the 3 o'clock or 9 o'clock position. If it is at the 9 o'clock position, more carbonized rice husks can be laid from the 3 o'clock to 12 o'clock position than from the 9 o'clock to 12 o'clock position during the material laying process. This is to further reduce the probability of slag shells forming from the 3 o'clock to 12 o'clock position and prevent the slag removal vehicle from being unable to clean the slag shells forming from the 3 o'clock to 12 o'clock position due to insufficient arm reach or other reasons.

[0028] 8. The cloth rotating chute is located at a point between the normal steel processing position and the ladle cover addition / removal position.

[0029] 9. The carbonized rice husk has the following composition: fixed carbon content ≥60%, H2O content ≤2%.

[0030] 10. Preferably, in order to prevent the molten steel from exceeding the standard due to the carbonization caused by the added carbonized rice husks, the carbon content of the molten steel is controlled within the middle to lower limit of the target requirement before adding the carbonized rice husks.

[0031] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0032] Before the technical upgrade, the method for cleaning the slag crust at the mouth of the covered steel ladle was as follows:

[0033] 1. For the second heat of 61309, heat 408258 of SWRCH6A steel, the ladle molten steel depth is 3208mm. After the normal (calcium) treatment of the molten steel is completed and it enters the soft blowing stage, add 4 bags of carbonized rice husks (about 7-8kg / bag) to the center 0 point of the ladle, and control the soft blowing flow rate at 5-10Nm. 3 After 5 minutes of soft blowing, the carbonized rice husks are spread out, with the flow rate controlled at 0-5 Nm³ / h. 3 After continuing soft blowing for 20 minutes, the ladle car is started and moved to the ladle position. The ladle is then lifted by the overhead crane and taken to the continuous casting ladle turret for pouring. The interval between the time it takes for the molten steel in the ladle to be lifted by the overhead crane and poured on the turret is 9 minutes.

[0034] 2. Pouring of molten steel was stopped 45 minutes later (i.e., during the pouring period, the average rate of molten steel level drop was 3208 mm / 45 min = 71.3 mm / min). The ladle was then lifted away from the ladle turret by an overhead crane. Slag removal was performed first, and after the ladle reached the hot repair position, a large amount of slag shell was found at the ladle opening (the slag shell area accounted for approximately 75% of the ladle opening area, see...). Figure 2After that, the slag removal operation was carried out, which took about 13 minutes to basically clean the slag shell at the mouth of the bag.

[0035] It is evident that using the above-described operation, there is a high probability of slag crust forming at the ladle opening, and cleaning the crust takes a long time.

[0036] Example 1: After technical modification, the method for cleaning the slag crust at the mouth of the covered steel ladle is as follows:

[0037] 1. For the third heat of 408259 SWRCH6A steel in casting batch 61309, with a ladle molten steel depth of 3115mm, after the normal (calcium) treatment of the molten steel is completed and it enters the soft blowing stage, add one bag of carbonized rice husks (approximately 7-8kg / bag) to each of the centers of the lines connecting the 0 point to the 3, 6, 9, and 12 points on the ladle (i.e., the ladle radius center) (totaling 4 bags). At the same time, control the bottom blowing air flow rate of the ladle to 5-10Nm. 3 / h, to ensure the carbonized rice husks are spread out quickly and evenly. After 5 minutes of soft blowing, drive the ladle car to the carbonized rice husk distribution position, while simultaneously reducing the bottom blowing air flow rate of the ladle to 0-5Nm. 3 / h.

[0038] 2. After continuing soft blowing for 10 minutes (25-5) / 2min, start moving the ladle car back and forth to make the slag interface sway back and forth. Use the swaying force to make the slag liquid level at 6 o'clock and 12 o'clock periodically higher and lower by about 180mm compared to the normal liquid level. At the same time, along the slag interface of the ladle wall, start spreading carbonized rice husks with a rotating chute from 3 o'clock to 12 o'clock to 9 o'clock. The weight of the carbonized rice husks spread on the semicircle is 9kg / m (calculated according to the diameter of the ladle mouth of 3.1m, the total weight of carbonized rice husks = 3.14*3.1 / 2m*9kg / m = 43.8kg), the spreading width is 130mm, and the total spreading time is 1.5min. After spreading, stop moving the ladle car and let the slag liquid level return to calm automatically. Then continue soft blowing.

[0039] 3. After stopping the feeding, at (25-5) / 4min = 5min, start the ladle car once, and use the swaying to make the slag liquid level at 6 o'clock and 12 o'clock about 180mm higher and lower than the normal liquid level. Immediately stop starting the ladle car, and then let the slag liquid level return to calm automatically. Then continue the soft blowing.

[0040] 4. After the molten steel is soft-blown and covered, start the ladle car back and forth once more. Use the swaying motion to make the slag level at 6 o'clock and 12 o'clock about 180mm higher and lower than the normal level. Immediately stop starting the ladle car and let the slag level return to calm automatically. The molten steel is then lifted by the overhead crane to the continuous casting ladle turret for pouring. The interval between the time the molten steel is lifted by the overhead crane and the time it is poured on the turret is 3 minutes.

[0041] 5. Pouring of molten steel was stopped 40 minutes later (i.e., during the pouring period, the average rate of molten steel level drop was 3115mm / 40min = 77.9mm / min). The ladle was then lifted away from the ladle turret by an overhead crane. Slag removal was performed first, and after the ladle reached the hot repair position, it was found that there was almost no slag shell at the ladle opening (the slag shell area accounted for approximately 1% of the ladle opening area, see...). Figure 3 After that, the slag removal operation was carried out, and it only took about 2 minutes to basically clean the slag shell at the mouth of the bag.

[0042] Comparative Example 1

[0043] Similar to the steps in Example 1, the only difference is that (Step 2 of Example 1) instead of spreading the material, 43.8 kg of carbonized rice husks were added to the slag surface by hand. After the ladle reached the hot repair position, it was found that the slag crust at the ladle opening accounted for approximately 40% of the ladle opening area. Figure 4 Then, the slag removal operation was carried out, which took about 8 minutes to basically clean the slag shell at the mouth of the bag.

[0044] Comparative Example 2

[0045] Similar to the steps in Example 1, the only difference is that (Step 2 of Example 1) the weight of the carbonized rice husks distributed along the semicircle is 5 kg / m (calculated based on a ladle opening diameter of 3.1 m, the total weight of the carbonized rice husks distributed = 3.14 * 3.1 / 2 m * 5 kg / m = 24.3 kg). After the ladle reaches the hot repair position, it is found that the slag crust area at the ladle opening accounts for approximately 19% of the ladle opening area. Figure 5 Then, the slag removal operation was carried out, which took about 6 minutes to basically clean the slag shell at the mouth of the bag.

[0046] Comparative Example 3

[0047] Similar to the steps in Example 1, the only difference is that (Step 4 of Example 1) the interval between the molten steel in the ladle being lifted by the overhead crane and being poured on the rotary table is 5 minutes. After the ladle finally reaches the hot repair position, it is found that the slag crust at the ladle opening accounts for approximately 13% of the ladle opening area. Figure 6 Then, the slag removal operation was carried out, which took about 5 minutes to basically clean the slag shell at the mouth of the bag.

[0048] Comparative Example 4

[0049] Similar to the steps in Example 1, the only difference is that (Step 5 of Example 1) the pouring of molten steel was stopped after 45 minutes (i.e., during the pouring of molten steel, the average rate of molten steel level drop was 3115mm / 45min = 69.2mm / min). Finally, after the ladle reached the hot repair position, it was found that the slag crust area at the ladle opening accounted for approximately 6% of the ladle opening area. (See...) Figure 7 Then, the slag removal operation was carried out, which took about 4 minutes to basically clean the slag shell at the mouth of the bag.

[0050] As can be seen from the above, before the technical upgrade, there was a high probability of slag crust forming at the ladle opening, and cleaning the crust was time-consuming. However, using the solution provided in this embodiment, the ladle is lifted from the ladle turret by a crane, followed by slag removal. After the ladle reaches the hot repair position, almost no slag crust is found at the ladle opening. In contrast, in the comparative example, when cleaning the slag crust at the opening of a covered ladle, changing conditions such as not placing material, changing the amount of material placed, changing the interval between the ladle being lifted by the crane and just before pouring on the turret, and changing the average rate of molten steel level drop, it was found that the area of ​​slag crust at the ladle opening increased, requiring more time to clean it thoroughly. This demonstrates that the solution provided in this embodiment can significantly and effectively reduce the amount of slag crust at the opening of covered ladles.

[0051] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of reducing cinder shell formation at the lip of a covered ladle, characterized in that, The application relates to a ladle with a cover, and relates to a ladle cover section equal division method. The ladle cover section is equally divided into four parts, and the 3 o'clock, 6 o'clock, 9 o'clock and 12 o'clock positions are marked according to a clock scale; the circumferential segment from 3 o'clock to 6 o'clock to 9 o'clock is set as a slag segment; when the calcium line feeding of the molten steel is completed and the soft blowing stage is entered, rice husk insulation is added to the center of the ladle; the carbonized rice husk is rapidly and uniformly spread in the soft blowing state; before and after the soft blowing is completed, the ladle car is started in the direction of the 6 o'clock and 12 o'clock connecting line; the 6 o'clock and 12 o'clock slag liquid surfaces are higher or lower than the normal level of the liquid surface by using the swing potential; the slag shell on the circumferential segment from 3 o'clock to 12 o'clock to 9 o'clock is caused to fall off, and wherein: When the molten steel enters the soft blowing stage, the rice hull heat insulating agent is added to the center of the ladle, including the following steps: when the molten steel feeding calcium line is finished and the molten steel enters the soft blowing stage, 7-8 kg of carbonized rice hull is added to each of the four radius centers of the ladle, and the bottom blowing gas flow of the ladle is controlled to be 5-10 Nm 3 / h, so that the carbonized rice hull is quickly and uniformly spread out, and after 5 minutes of soft blowing, the ladle car is opened to the carbonized rice hull distribution position, and the bottom blowing gas flow of the ladle is reduced to 0-5 Nm 3 / h. Before and after the soft blowing is completed, the ladle car is started, including the following steps: the ladle car is started once in the remaining 1 / 2 time before the soft blowing is completed; the ladle car is started once in the remaining 1 / 4 time before the soft blowing is completed; and the ladle car is started once again after the molten steel soft blowing is completed. The application further comprises the following steps: the position of the device for removing the slag shell of the ladle cover is identified; if the device for removing the slag shell of the ladle cover is at the 9 o'clock position, the amount of carbonized rice husk in the 3 o'clock to 12 o'clock region is controlled to be greater than that in the 9 o'clock to 12 o'clock region, so as to further reduce the slag shell probability in the 3 o'clock to 12 o'clock region. The application further comprises the following steps: before the carbonized rice husk is added, the carbon content in the molten steel is controlled in the middle limit-lower limit range of the target requirement; and the fixed carbon content in the carbonized rice husk is preferably greater than or equal to 60%, and the H2O content is less than or equal to 2%.

2. The method of reducing cinder shell buildup on the lip of a covered steel ladle of claim 1 wherein, The ladle car is started once in the remaining 1 / 2 time before the soft blowing is completed, including the following steps: the ladle car is started in the direction of the 6 o'clock and 12 o'clock connecting line in the remaining 1 / 2 time before the soft blowing is completed; the molten steel and slag interface is shaken; the 6 o'clock and 12 o'clock slag liquid surfaces are periodically higher or lower than the normal level of the liquid surface by 0-200mm by using the swing potential; the carbonized rice husk is distributed along the molten steel and slag interface of the ladle wall from the circumferential segment from 3 o'clock to 12 o'clock to 9 o'clock or from 9 o'clock to 12 o'clock to 3 o'clock; the weight of the carbonized rice husk per unit length on the half circumferential length is 5-10kg / m; the distribution width is 50-150mm; the total distribution time is less than or equal to 2min; after the distribution is completed, the ladle car is stopped; and the molten steel and slag liquid surface is automatically restored to be calm.

3. The method of reducing cinder shell buildup on the lip of a covered steel ladle of claim 1 wherein, The ladle car is started once in the remaining 1 / 4 time before the soft blowing is completed, including the following steps: after the distribution is stopped, the ladle car is started in the direction of the 6 o'clock and 12 o'clock connecting line once; the 6 o'clock and 12 o'clock slag liquid surfaces are higher or lower than the normal level of the liquid surface by 0-200mm by using the swing potential; the ladle car is immediately stopped; and then the molten steel and slag liquid surface is automatically restored to be calm.

4. The method of reducing cinder shell buildup on the lip of a covered steel ladle of claim 1 wherein, The ladle car is started once again after the molten steel soft blowing is completed, including the following steps: after the molten steel soft blowing is completed, the ladle car is started in the direction of the 6 o'clock and 12 o'clock connecting line once again; the 6 o'clock and 12 o'clock slag liquid surfaces are higher or lower than the normal level of the liquid surface by 0-200mm by using the swing potential; the ladle car is immediately stopped; then the molten steel and slag liquid surface is automatically restored to be calm; and then the ladle with the cover is lifted to the continuous casting ladle rotating table for casting.

5. The method of reducing cinder shell buildup on the lip of a covered steel ladle of claim 4 wherein, The interval time before the ladle with the cover is lifted to the rotating table for casting is controlled to be less than or equal to 8min.

6. The method of reducing cinder shell buildup on the lip of a covered steel ladle of claim 5 wherein, During the molten steel casting, the molten steel surface descending speed is controlled to be greater than or equal to 75mm / min.

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