Method for reducing steel ladle casting temperature drop and refining furnace

Abstract

The invention relates to the technical field of steel smelting, and particularly discloses a method for reducing steel ladle casting temperature drop and a refining furnace. The method for reducing the casting temperature drop of the steel ladle comprises the following steps: measuring the thickness of a slag layer in the steel ladle as a detection thickness before molten steel refining is finished and exits from a station; according to the detection thickness of the slag layer, the basic adding amount of the steel ladle covering agent needed by the current steel ladle is determined according to the corresponding relation between the thickness of the slag layer and the adding amount of the steel ladle covering agent; according to the determined basic adding amount of the steel ladle covering agent needed by the current steel ladle, the steel ladle covering agent with the corresponding amount is blown into the current steel ladle through a powder spraying device arranged on the refining furnace cover, the powder spraying device comprises at least one circle of nozzles distributed in a circular ring shape, and the multiple nozzles in each circle are evenly distributed in the circumferential direction. According to the method for reducing the casting temperature drop of the steel ladle and the refining furnace, the slag surface can be better covered by a small amount of steel ladle covering agent, and the steel ladle covering agent on the slag surface is more uniformly distributed, so that a better heat preservation effect is achieved, and the casting temperature drop of the steel ladle is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of steel smelting, and more particularly to a method for reducing ladle casting temperature drop and a refining furnace. Background Art

[0002] Steelmaking ladles are mainly used to store and transport molten steel and maintain its temperature. The temperature of the molten steel in the ladle is related to the smooth casting and the quality of the ingot. With the continuous expansion of steelmaking production and the development of continuous casting technology, the capacity of the ladle has increased, and the time the molten steel stays in the ladle has been correspondingly extended. In order to reduce the temperature drop of the ladle casting, a ladle covering agent is usually added to the surface of the molten steel in the ladle for insulation and heat preservation.

[0003] The ladle covering agent is generally added from the discharge port of the water-cooled furnace cover of the high-level silo in the refining process. During refining, when the ladle is opened to the processing position, the water-cooled furnace cover falls down, and a discharge port is opened above the water-cooled furnace cover. The ladle covering agent in the high-level silo is added into the ladle through the discharge port. However, the ladle covering agent in the above-mentioned adding method is easy to clump on the slag surface, and the ladle covering agent on the slag surface is uneven. The covering agent has limited protection for the ladle slag layer and cannot completely cover the slag surface, thereby affecting the effect of heat preservation and oxidation isolation, and the ladle casting temperature drop is large. In addition, the amount of ladle covering agent required to better cover the slag surface is large, so the cost is also high.

[0004] In summary, how to effectively solve the problem of large temperature drop in ladle casting is a problem that technical personnel in this field need to solve. Summary of the invention

[0005] In view of this, an object of the present invention is to provide a method for reducing the temperature drop of ladle casting and a refining furnace, which can effectively solve the problem of large temperature drop of ladle casting.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for reducing ladle casting temperature drop, comprising:

[0008] Before the molten steel leaves the station after refining, the thickness of the slag layer in the ladle is measured as the detection thickness;

[0009] According to the detected thickness of the slag layer, the basic amount of ladle covering agent added required for the current ladle is determined from the corresponding relationship between the slag layer thickness and the amount of ladle covering agent added;

[0010] According to the determined basic addition amount of ladle covering agent required for the current ladle, a corresponding amount of ladle covering agent is sprayed into the current ladle through a powder spraying device arranged on the refining furnace cover, wherein the powder spraying device includes at least one circle of nozzles distributed in a circular ring shape, and the multiple nozzles in each circle are evenly distributed along the circumferential direction.

[0011] Optionally, in the above method for reducing the ladle casting temperature drop, according to the determined basic amount of ladle covering agent required for the current ladle, a corresponding amount of ladle covering agent is sprayed into the current ladle through a powder spraying device provided on the refining furnace cover, specifically comprising:

[0012] Determine whether the current ladle is an abnormal ladle;

[0013] If yes, spray the ladle covering agent into the current ladle through the powder spraying device arranged on the refining furnace cover, and the spraying amount of the ladle covering agent is the sum of the basic addition amount and the supplementary addition amount, and the range of the supplementary addition amount is 25-35 kg / furnace;

[0014] Otherwise, the ladle covering agent is sprayed into the current ladle through the powder spraying device arranged on the refining furnace cover, and the spraying amount of the ladle covering agent is the basic addition amount;

[0015] Among them, the abnormal ladles include the ladles used three times before being put into use, the drying ladle and the insulation ladle.

[0016] Optionally, in the above method for reducing the temperature drop of ladle casting, the thickness of the slag layer is inversely correlated with the basic addition amount of the ladle covering agent.

[0017] Optionally, in the above method for reducing the temperature drop of ladle casting, when the thickness of the slag layer is not less than 60 mm, the basic addition amount of the ladle covering agent is in the range of 105-95 kg / furnace;

[0018] When the thickness of the slag layer is not less than 10 mm, the basic addition amount of the ladle covering agent is in the range of 155-145 kg / furnace;

[0019] When the thickness of the slag layer is greater than 10 mm and less than 60 mm, the basic addition amount of the ladle covering agent increases as the thickness of the slag layer decreases.

[0020] Optionally, in the above method for reducing the ladle casting temperature drop, according to the detected thickness of the slag layer, the basic amount of ladle covering agent required for the current ladle is determined by the corresponding relationship between the slag layer thickness and the amount of ladle covering agent added, specifically including:

[0021] The detected thickness of the slag layer is rounded off to ten places to obtain an approximate value;

[0022] When the approximate value is not less than 60 mm, the basic addition amount of the ladle covering agent is in the range of 98-102 kg / furnace;

[0023] When the approximate values ​​are 10mm, 20mm, 30mm, 40mm and 50mm respectively, the basic addition amount of the ladle covering agent ranges from 148 to 152kg / furnace, 138 to 142kg / furnace, 128 to 132kg / furnace, 118 to 122kg / furnace and 108 to 112kg / furnace respectively.

[0024] Optionally, in the above method for reducing the temperature drop of ladle casting, each of the nozzles is distributed in a circular ring with the center of the ladle as the center.

[0025] Optionally, in the above method for reducing the temperature drop of ladle casting, the outlet direction of each nozzle is obliquely downward and forms an angle of 15° to 25° with the vertical direction, and the projection of the outlet direction on the horizontal plane is along the radial direction of the ring and toward the center of the circle.

[0026] Optionally, in the above method for reducing the ladle casting temperature drop, after the powder spraying device sprays a corresponding amount of ladle covering agent into the current ladle, the method further comprises:

[0027] Detecting the spreading state of the ladle covering agent on the slag surface;

[0028] If the ladle covering agent is not fully spread on the slag surface, the nozzle corresponding to the position not covered by the ladle covering agent is controlled to continue spraying the ladle covering agent until the ladle covering agent is fully spread on the slag surface.

[0029] Optionally, in the above-mentioned method for reducing the temperature drop of ladle casting, the nozzle is rotatably provided on the refining furnace cover, and when the ladle covering agent is not fully spread on the slag surface, the angle of the nozzle closest to the position not covered by the ladle covering agent is adjusted to face the position not covered by the ladle covering agent and continue to spray the ladle covering agent.

[0030] A refining furnace, used in any of the above methods for reducing ladle casting temperature drop, comprising:

[0031] A refining furnace body, wherein the top of the refining furnace body is open;

[0032] A refining furnace cover, arranged at the opening;

[0033] A powder spraying device is arranged on the refining furnace cover, and the powder spraying device comprises at least one circle of nozzles distributed in a circular ring shape, and a plurality of nozzles in each circle are evenly distributed along the circumferential direction.

[0034] The method and refining furnace for reducing the temperature drop of ladle casting provided by the present invention are applied. A powder spraying device is arranged on the refining furnace cover. The powder spraying device includes at least one circle of nozzles distributed in a circular ring shape, and multiple nozzles in each circle are evenly distributed along the circumference. Before the molten steel is finished refining and leaves the station, the thickness of the slag layer in the ladle is measured, and the thickness value obtained by the measurement is used as the detection thickness. According to the detected thickness of the slag layer, the basic addition amount of the ladle covering agent required for the current ladle is determined by the corresponding relationship between the slag layer thickness and the addition amount of the ladle covering agent, and the ladle covering agent corresponding to the basic addition amount is sprayed into the current ladle through the powder spraying device.

[0035] In summary, the method and refining furnace for reducing the temperature drop of ladle casting provided by the present invention replace the conventional material discharge from the high-level silo by the covering agent spraying, and the ladle covering agent can be better spread on the slag surface to avoid caking, so that the slag surface can be better covered by a smaller amount of ladle covering agent, and the distribution of the ladle covering agent on the slag surface is more uniform, so as to play a better heat preservation effect and reduce the temperature drop of ladle casting. In addition, the amount of ladle covering agent added is determined according to the thickness of the slag layer. The slag layer also has a certain heat preservation effect. The thicker the slag layer, the better the heat preservation effect, and the less the amount of ladle covering agent used; conversely, the more the amount of ladle covering agent used. Therefore, the amount of ladle covering agent added is determined according to the thickness of the slag layer. On the basis of ensuring the heat preservation effect, the amount of ladle covering agent added is further reduced, thereby reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 A schematic flow chart of a method for reducing ladle casting temperature drop according to a specific embodiment of the present invention;

[0038] Figure 2 The figure is a schematic cross-sectional view of a refining furnace according to a specific embodiment of the present invention.

[0039] Reference numerals:

[0040] 1-refining furnace body; 11-opening; 2-refining furnace cover; 3-powder spraying device; 31-nozzle. DETAILED DESCRIPTION

[0041] The embodiment of the invention discloses a method for reducing the temperature drop of ladle casting and a refining furnace, so as to effectively reduce the temperature drop of ladle casting.

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The conventional method of adding protective slag requires a large amount of addition on the one hand, and on the other hand, it is easy to clump on the slag surface and the coverage is uneven. Therefore, how to ensure that the covering agent completely covers the ladle slag surface becomes a major problem. To this end, the present application provides a method and a refining furnace for reducing the temperature drop of ladle casting. The covering agent is sprayed on the slag surface through an annular blowing device to ensure that the slag surface of the ladle has a covering agent, which has a positive effect on preventing the secondary oxidation of molten steel, effectively reducing the temperature drop of ladle casting, and providing molten steel at a suitable temperature for continuous casting, ensuring its smooth casting. It can be understood that the present application has improved the method and amount of adding the ladle covering agent. Specifically, the timing of adding the ladle covering agent in the steelmaking process is the same as the conventional addition timing.

[0044] In some specific embodiments, see Figure 1 The method for reducing the temperature drop of ladle casting provided in the present application comprises the following steps:

[0045] S1: Before the molten steel leaves the station after refining, measure the thickness of the slag layer in the ladle as the detection thickness;

[0046] For example, after the molten steel refining in the ladle refining furnace is finished and before the soft blowing station is discharged, the thickness of the slag layer on the molten steel in the ladle, i.e., the slag, is first measured. The specific slag layer thickness detection method can adopt conventional detection means in the prior art, which will not be described here. The slag layer obtained after the detection is used as the detection thickness, and this is used as the basis for the amount of ladle covering agent to be added.

[0047] Exemplarily, the thickness of the slag layer is measured by the metal color melting method, such as using an aluminum bar to make a slag gauge, specifically bending the aluminum bar into a Z shape, including a middle section and a short head section and a long head section connected to both ends of the middle section and extending in opposite directions and of different lengths. When measuring, insert the short head section of the manufactured slag gauge downward into the molten steel, visually observe that the middle part of the aluminum bar is flat on the edge of the ladle, and pull it out after entering the molten steel and melting. Measure the remaining length of the short head aluminum bar, which is the clearance; measure the length of the aluminum bar with slag, which is the slag thickness.

[0048] S2: According to the detected thickness of the slag layer, the basic amount of ladle covering agent added required for the current ladle is determined based on the corresponding relationship between the slag layer thickness and the amount of ladle covering agent added;

[0049] The correspondence between the slag layer thickness and the amount of ladle covering agent added is established in advance. Then, according to the detected thickness of the slag layer obtained by detection, the basic amount of ladle covering agent added required by the current ladle can be determined by signing the corresponding relationship, that is, the basic amount of addition corresponding to the current ladle and the detected thickness satisfy the pre-established correspondence between the slag layer thickness and the amount of ladle covering agent added. It can be understood that the correspondence between the slag layer thickness and the amount of ladle covering agent added can be a functional relationship, and the corresponding basic amount can be obtained by calculation according to the detected thickness. The correspondence between the slag layer thickness and the amount of ladle covering agent added can also be a correspondence in the form of a data table, and the corresponding basic amount can be determined by reading the data table and comparing according to the detected thickness.

[0050] S3: According to the determined basic addition amount of ladle covering agent required for the current ladle, a corresponding amount of ladle covering agent is sprayed into the current ladle through a powder spraying device provided on the refining furnace cover, wherein the powder spraying device includes at least one circle of nozzles distributed in a circular ring shape, and a plurality of nozzles in each circle are evenly distributed along the circumferential direction.

[0051] Different from the conventional method of adding ladle covering agents, a powder spraying device is provided on the refining furnace cover in the present application to spray the ladle covering agent onto the slag surface in the ladle. And the powder spraying device includes at least one circle of nozzles distributed in a circular ring shape, and the multiple nozzles in each circle are evenly distributed along the circumference. It can be understood that the powder spraying device includes multiple nozzles, and the multiple nozzles are distributed along the circular path for at least one circle, and the nozzles in each circle are evenly distributed along the circumference. In one example, the nozzles of the powder spraying device are distributed in one circle, and each nozzle is evenly distributed along the circumference. In another example, the nozzles of the powder spraying device are distributed in two or more circles, and the multiple nozzles in each circle are evenly distributed along the corresponding circumference. With such a configuration, when the ladle covering agent is sprayed onto the slag surface in the ladle, it can be sprayed evenly toward the slag surface from the circumference, so that the distribution of the ladle covering agent on the slag surface is more even.

[0052] The method for reducing the temperature drop of ladle casting provided by the present invention replaces the conventional material discharge from the high-level silo by the covering agent spraying, and the ladle covering agent can be better spread on the slag surface to avoid caking, so that the slag surface can be better covered by a smaller amount of ladle covering agent, and the distribution of the ladle covering agent on the slag surface is more uniform, so as to play a better heat preservation effect and reduce the temperature drop of ladle casting. In addition, the amount of ladle covering agent added is determined according to the thickness of the slag layer. The slag layer also has a certain heat preservation effect. The thicker the slag layer, the better the heat preservation effect, and the less the amount of ladle covering agent used; conversely, the more the amount of ladle covering agent used. Therefore, the amount of ladle covering agent added is determined according to the thickness of the slag layer. On the basis of ensuring the heat preservation effect, the amount of ladle covering agent added is further reduced, thereby reducing the cost.

[0053] In some embodiments, in the above step S3, according to the determined basic amount of ladle covering agent required for the current ladle, a corresponding amount of ladle covering agent is sprayed into the current ladle through a powder spraying device provided on the refining furnace cover, specifically comprising:

[0054] S31: Determine whether the current ladle is an abnormal ladle, if so, execute step S32, otherwise execute step S33;

[0055] S32: spraying a ladle covering agent into the current ladle through a powder spraying device arranged on the refining furnace cover, and the spraying amount of the ladle covering agent is the sum of the basic addition amount and the supplementary addition amount, and the range of the supplementary addition amount is 25-35 kg / furnace;

[0056] S33: Otherwise, spraying the ladle covering agent into the current ladle through the powder spraying device provided on the refining furnace cover, and the spraying amount of the ladle covering agent is the basic added amount;

[0057] Among them, abnormal ladles include the ladles used in the first three times after being put into use, the drying ladle and the insulation ladle.

[0058] In the ladle turnover cycle, for the ladle with normal turnover, that is, the ladle that can be used continuously after the current use without an intermittent period in between, the actual amount of ladle covering agent added can be the basic amount determined above. For abnormal ladles, that is, the ladle used in the first three times of new use, the drying ladle and the insulation ladle, the actual amount of ladle covering agent added needs to be the basic amount determined above, specifically the sum of the basic amount and the supplementary amount. Since the ladle used in the first three times of new use further absorbs the temperature of the molten steel, the temperature of the molten steel drops faster, so the required ladle covering agent content is higher, so as to effectively reduce the casting temperature drop of the ladle. The drying ladle refers to a ladle that has not been used for several hours and has not been returned to the ladle room for insulation, specifically refers to a ladle that has not been used for 1 hour or more and has not been returned to the ladle room for insulation. The insulation ladle refers to a ladle that has not been used for several hours and has been returned to the ladle room for baking and insulation, specifically refers to a ladle that has not been used for 1 hour or more and has been returned to the ladle room for baking and insulation. According to the different conditions of the ladle, the amount of ladle covering agent sprayed is adjusted accordingly to further improve the insulation effect.

[0059] Exemplarily, the basic addition amount of ladle covering corresponding to a normal ladle is in the range of 100-150kg / heat, and the abnormal ladle is added with 25~35kg / heat more ladle covering on this basis, that is, the supplementary addition amount ranges from 25~35kg / heat, specifically, the supplementary addition amount is 20kg / heat.

[0060] In some embodiments, the thickness of the slag layer is inversely correlated with the basic addition amount of the ladle covering agent. Since the slag layer has a certain heat preservation effect, the corresponding relationship between the thickness of the slag layer and the addition amount of the ladle covering agent is set to be inversely correlated with the basic addition amount of the ladle covering agent, and the corresponding basic addition amount can be accurately determined according to the detected thickness. The specific proportional coefficient between the two can be obtained by experiment or simulation, etc., and is not specifically limited here.

[0061] In some embodiments, when the thickness of the slag layer is not less than 60 mm, the basic addition amount of the ladle covering agent ranges from 105 to 95 kg / furnace; when the thickness of the slag layer is not less than 10 mm, the basic addition amount of the ladle covering agent ranges from 155 to 145 kg / furnace; when the thickness of the slag layer is greater than 10 mm and less than 60 mm, the basic addition amount of the ladle covering agent increases as the thickness of the slag layer decreases. When the thickness of the slag layer is greater than 60 mm, the basic addition amount is the basic addition amount corresponding to the slag layer thickness of 60 mm, that is, the basic addition amount is a determined value; when the thickness of the slag layer is less than 10 mm, the basic addition amount is the basic addition amount corresponding to the slag layer thickness of 10 mm, that is, the basic addition amount is a determined value. As set above, the basic addition amount decreases as the slag layer thickness increases within the range of 10 mm to 60 mm, and when the slag layer thickness exceeds this range, the basic addition amount no longer changes accordingly. This ensures that the basic addition amount is within a certain range. The lower limit of the basic addition amount is 105~95kg / furnace, and the upper limit is 155~145kg / furnace. That is, the basic addition amount is neither too little to completely cover the slag surface, nor too much to cause excessive cost.

[0062] In some embodiments, in the above step S2, according to the detected thickness of the slag layer, the basic amount of the ladle covering agent required for the current ladle is determined by the corresponding relationship between the slag layer thickness and the amount of the ladle covering agent added, specifically including:

[0063] S21: round the detected thickness of the slag layer to the nearest ten and take an approximate value;

[0064] S22: When the approximate value is not less than 60mm, the basic addition amount of the ladle covering agent ranges from 98 to 102kg / furnace; when the approximate values ​​are 10mm, 20mm, 30mm, 40mm, and 50mm, respectively, the basic addition amount of the ladle covering agent ranges from 148 to 152kg / furnace, 138 to 142kg / furnace, 128 to 132kg / furnace, 118 to 122kg / furnace, and 108 to 112kg / furnace, respectively.

[0065] When determining the basic addition amount corresponding to the detected thickness according to the functional relationship between the slag layer thickness and the addition amount of the ladle covering agent, it is necessary to calculate and obtain it, and the amount of calculation is large. Therefore, in this embodiment, the detected thickness is approximated, and the basic addition amount of the ladle covering agent corresponding to the approximate value is established. Then, according to the detected thickness of the slag layer, the corresponding basic addition amount can be determined without function calculation, and the amount of calculation is small. In addition, according to the influence of the slag layer thickness on the thermal insulation effect, the detected thickness is rounded to ten places to take the approximate value, so that the influence of the slag layer thickness on the thermal insulation effect can be accurately measured, so there is no need for function calculation.

[0066] Exemplarily, the detected thickness of the slag layer is rounded to ten and the approximate value is taken. The relationship between the approximate value and the basic addition amount is shown in Table 1.

[0067] Table 1 Relationship between slag layer thickness and basic addition amount of ladle covering agent

[0068]

[0069] In some embodiments, each nozzle is distributed in a ring shape with the center of the ladle as the center. That is, the distribution trajectory of each nozzle is in a ring shape, and the circle of the ring shape is located in the center of the ladle, so that the ladle covering agent sprayed by each nozzle is more evenly distributed on the slag surface in the ladle, and less ladle covering agent can fully cover the slag surface.

[0070] In some embodiments, the outlet direction of each nozzle is obliquely downward and at an angle of 15° to 25° with the vertical direction, and the projection of the outlet direction in the horizontal plane is along the radial direction of the ring and toward the center of the circle. The nozzle is located above the slag surface, so the nozzle is set obliquely downward, that is, the blowing direction is set obliquely downward, and the sprayed ladle covering agent can be better spread on the slag surface, that is, the ladle covering agent does not fall vertically in the process of falling to the slag surface, but has a certain displacement in the horizontal direction, so that the area that can be spread on the slag surface is larger and not easy to form lumps. In addition, each nozzle is evenly distributed along the circumference, and the projection of the blowing direction of each nozzle in the horizontal plane is along the radial direction of the ring, and is toward the center of the circle, that is, blown inward, and the distribution of the ladle covering agent sprayed on the slag surface in the ladle is more uniform. Exemplarily, the outlet direction of each nozzle is at an angle of 20° with the vertical direction.

[0071] In some embodiments, the center lines of the annularly distributed nozzles are 250 mm away from the outside of the cover to ensure a good powder spraying effect.

[0072] In some embodiments, after the powder spraying device sprays a corresponding amount of ladle covering agent into the current ladle, the step further includes:

[0073] S5: Detect the spreading state of the ladle covering agent on the slag surface;

[0074] S6: If the ladle covering agent is not fully spread on the slag surface, the nozzles corresponding to the positions not covered by the ladle covering agent are controlled to continue spraying the ladle covering agent until the ladle covering agent is fully spread on the slag surface.

[0075] In this embodiment, each nozzle can be controlled to open or close individually. For example, each nozzle is provided with a valve. When the valve is opened, the corresponding nozzle is started to spray the ladle covering agent; when the valve is closed, the corresponding nozzle stops spraying the ladle covering agent. After spraying the corresponding amount of ladle covering agent in the manner described in the above embodiments, the spreading state of the ladle covering agent on the slag surface is detected, and according to the spreading state of the ladle covering agent, additional spraying can be performed to finally make the ladle covering agent spread all over the slag surface. In addition, in order to avoid the addition of additional ladle covering agent, when supplementing the spraying, according to the position of the slag surface lacking the ladle covering agent, that is, for the slag surface area already covered with the ladle covering agent, the ladle covering agent is no longer sprayed, and only for the slag surface area not covered with the ladle covering agent, the nozzle corresponding to the area is used for supplementary spraying, and the nozzle that can spray to the area continues to spray the ladle covering agent until it is detected that the ladle covering agent is fully spread on the slag surface. Exemplarily, the nozzles corresponding to the positions not covered by the ladle covering agent are controlled to continue spraying the ladle covering agent. Specifically, each nozzle within a fan-shaped range with the center of the ladle as the center corresponding to the positions not covered by the ladle covering agent can be controlled to continue spraying the ladle covering agent.

[0076] In some embodiments, the nozzle is rotatably mounted on the refining furnace cover, and when the ladle covering agent is not fully spread on the slag surface, the angle of the nozzle closest to the position where the ladle covering agent is not covered is adjusted to face the position where the ladle covering agent is not covered and continue to spray the ladle covering agent. In this embodiment, the nozzle is rotatably mounted, and when it is detected that there is an area on the slag surface that is not covered with the ladle covering agent, the nozzle closest to the area is controlled to rotate to face the area and continue to spray the ladle covering agent until it is detected that the ladle covering agent fully covers the slag surface. As set above, the spraying direction of the nozzle can be accurately controlled to perform supplementary spraying in a more targeted manner, thereby further reducing the amount of the ladle covering agent while ensuring that the ladle covering agent fully covers the slag surface, thereby saving costs.

[0077] The present application also provides a refining furnace for use in any of the above methods for reducing the temperature drop of ladle casting. Figure 2, the refining furnace comprises a refining furnace body 1, a refining furnace cover 2 and a powder spraying device 3. Among them, the top end of the refining furnace body 1 has an opening 11; the refining furnace cover 2 is arranged at the opening 11. The specific matching mode of the refining furnace body 1 and the refining furnace cover 2 can refer to the setting of a conventional refining furnace, and is not specifically limited here. The powder spraying device 3 is arranged on the refining furnace cover 2, and the powder spraying device 3 includes at least one circle of nozzles 31 distributed in a circular ring shape, and the multiple nozzles 31 in each circle are evenly distributed along the circumference. The powder spraying device 3 includes a plurality of nozzles 31, and the multiple nozzles 31 are distributed along the circular path for at least one circle, and the nozzles 31 in each circle are evenly distributed along the circumference. In one example, the nozzles 31 of the powder spraying device 3 are distributed in one circle, and each nozzle 31 is evenly distributed along the circumference. In another example, the nozzles 31 of the powder spraying device 3 are distributed in two or more circles, and the multiple nozzles 31 in each circle are evenly distributed along the corresponding circumference. With such arrangement, when the ladle covering agent is sprayed onto the slag surface in the ladle, it can be sprayed evenly toward the slag surface from the circumferential direction, so that the distribution of the ladle covering agent on the slag surface is more even.

[0078] The refining furnace provided by the present invention is provided with a powder spraying device 3 to spray the ladle covering agent instead of conventionally unloading from a high-level silo. The ladle covering agent can be better spread on the slag surface to avoid caking. Therefore, the slag surface can be better covered by a smaller amount of ladle covering agent, and the distribution of the ladle covering agent on the slag surface is more uniform, so as to play a better insulation role and reduce the ladle casting temperature drop. In addition, the amount of ladle covering agent added is determined according to the thickness of the slag layer. The slag layer also has a certain insulation effect. The thicker the slag layer, the better the insulation effect, and the less the amount of ladle covering agent used; conversely, the more the amount of ladle covering agent used. Therefore, the amount of ladle covering agent added is determined according to the thickness of the slag layer. On the basis of ensuring the insulation effect, the amount of ladle covering agent added is further reduced, thereby reducing the cost.

[0079] The specific structure of each nozzle 31 in the powder spraying device 3 can refer to the relevant settings in the above embodiments, and will not be repeated here.

[0080] The following is a comparative description of two specific embodiments and corresponding comparative examples.

[0081] Example 1

[0082] 150 ton refining process reduces ladle casting temperature drop

[0083] An annular powder spraying device is added to the refining furnace cover; the center line of the annular powder spraying device is 250mm away from the outer side of the refining ladle cover, and the spray angle of the nozzle outlet, i.e. the blowing hole, is 20° downward from the vertical.

[0084] The slag thickness was measured to be 26mm before leaving the station, which was rounded off to 30mm. The ladle was a normal turnover ladle. According to the correspondence between the slag layer thickness and the amount of ladle covering agent added, the amount of ladle covering agent added for this heat was 130kg, and it was sprayed onto the slag surface of the ladle.

[0085] This furnace produced HRB400E with a liquidus of 1507°C. During casting, the temperature of the tundish was controlled at 1513-1527°C, the outlet temperature was 1552°C, the casting lasted 33 minutes, the highest casting temperature of the tundish was 1525°C, the lowest casting temperature of the tundish was 1518°C, the average casting temperature was 1521.6°C, and the casting temperature drop of this furnace was 7°C.

[0086] Example 2

[0087] 150 ton refining process reduces ladle casting temperature drop

[0088] An annular powder spraying device is added to the refining furnace cover; the center line of the annular powder spraying device is 250mm away from the outside of the refining ladle cover, and the spraying angle of the spray hole is 20° downward from the vertical.

[0089] The slag thickness was measured to be 43mm before leaving the station, which was rounded to 40mm. The ladle was a new ladle twice, which was an abnormal ladle. According to the correspondence between the slag layer thickness and the amount of ladle covering agent added, the basic addition amount and the supplementary addition amount were determined. The amount of ladle covering agent added for this furnace was 150kg, and it was sprayed onto the slag surface of the ladle.

[0090] This furnace produced HRB400E with a liquidus of 1507°C. During casting, the temperature of the tundish was controlled at 1513-1527°C, the outlet temperature was 1554°C, the casting was 30 minutes, the highest casting temperature of the tundish was 1526°C, the lowest casting temperature of the tundish was 1517°C, the average casting temperature was 1522.4°C, and the casting temperature drop of this furnace was 9°C.

[0091] Comparative Example 1

[0092] Normal control of temperature drop during 150 ton refining process

[0093] Before the ladle leaves the station, 120kg of ladle covering agent is added from the lower material port of the water-cooled furnace cover through the high-level silo. The ladle is a normal turnover ladle.

[0094] This furnace produced HRB400E with liquidus at 1507℃. During casting, the temperature of the tundish was controlled at 1513~1527℃, the outlet temperature was 1551℃, the casting took 32 minutes, the highest casting temperature of the tundish was 1525℃, the lowest casting temperature of the tundish was 1513℃, the average casting temperature was 1519.5℃, and the casting temperature drop of this furnace was 12℃.

[0095] Comparative Example 2

[0096] Normal control of temperature drop during 150 ton refining process

[0097] Before the ladle leaves the station, 120kg of ladle covering agent is added from the lower feed port of the water-cooled furnace cover through the high-level silo. The ladle has been out of the oven for 6 hours, which is an abnormal ladle.

[0098] This furnace produced HRB400E with liquidus at 1507℃. During casting, the temperature of the tundish was controlled at 1513~1527℃, the outlet temperature was 1553℃, the casting time was 31min, the highest casting temperature of the tundish was 1527℃, the lowest casting temperature of the tundish was 1511℃, the average casting temperature was 1518.3℃, and the casting temperature drop of this furnace was 16℃.

[0099] The data of Example 1 and Example 2 were compared with Comparative Example 1 and Comparative Example 2 after 20 tests, and the results are shown in Table 2. It can be seen that the method for reducing the temperature drop of ladle casting provided by the present application can effectively reduce the temperature drop of the casting process by about 3°C, ensuring smooth production of the casting process.

[0100] Table 2 Casting temperature of Examples 1 and 2 and Comparative Examples 1 and 2

[0101]

[0102] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0103] 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 reducing ladle casting temperature drop, characterized in that: include: Before the molten steel leaves the station after refining, the thickness of the slag layer in the ladle is measured as the detection thickness; According to the detected thickness of the slag layer, the basic amount of ladle covering agent added required for the current ladle is determined from the corresponding relationship between the slag layer thickness and the amount of ladle covering agent added; According to the determined basic addition amount of ladle covering agent required for the current ladle, a corresponding amount of ladle covering agent is sprayed into the current ladle through a powder spraying device arranged on the refining furnace cover, wherein the powder spraying device includes at least one circle of nozzles distributed in a circular ring shape, and the multiple nozzles in each circle are evenly distributed along the circumferential direction.

2. The method for reducing ladle casting temperature drop according to claim 1, characterized in that: According to the determined basic addition amount of ladle covering agent required for the current ladle, a corresponding amount of ladle covering agent is sprayed into the current ladle through a powder spraying device arranged on the refining furnace cover, specifically including: Determine whether the current ladle is an abnormal ladle; If yes, spray the ladle covering agent into the current ladle through the powder spraying device arranged on the refining furnace cover, and the spraying amount of the ladle covering agent is the sum of the basic addition amount and the supplementary addition amount, and the range of the supplementary addition amount is 25-35 kg / furnace; Otherwise, the ladle covering agent is sprayed into the current ladle through the powder spraying device arranged on the refining furnace cover, and the spraying amount of the ladle covering agent is the basic addition amount; Among them, the abnormal ladles include the ladles used three times before being put into use, the drying ladle and the insulation ladle.

3. The method for reducing ladle casting temperature drop according to claim 1, characterized in that: The thickness of the slag layer is inversely correlated with the basic addition amount of the ladle covering agent.

4. The method for reducing ladle casting temperature drop according to claim 1, characterized in that: When the thickness of the slag layer is not less than 60 mm, the basic addition amount of the ladle covering agent is in the range of 105-95 kg / furnace; When the thickness of the slag layer is not less than 10 mm, the basic addition amount of the ladle covering agent is in the range of 155-145 kg / furnace; When the thickness of the slag layer is greater than 10 mm and less than 60 mm, the basic addition amount of the ladle covering agent increases as the thickness of the slag layer decreases.

5. The method for reducing ladle casting temperature drop according to claim 1, characterized in that: According to the detected thickness of the slag layer, the basic amount of ladle covering agent required for the current ladle is determined by the corresponding relationship between the slag layer thickness and the amount of ladle covering agent added, specifically including: The detected thickness of the slag layer is rounded off to ten places to obtain an approximate value; When the approximate value is not less than 60 mm, the basic addition amount of the ladle covering agent is in the range of 98-102 kg / furnace; When the approximate values ​​are 10mm, 20mm, 30mm, 40mm and 50mm respectively, the basic addition amount of the ladle covering agent ranges from 148 to 152kg / furnace, 138 to 142kg / furnace, 128 to 132kg / furnace, 118 to 122kg / furnace and 108 to 112kg / furnace respectively.

6. The method for reducing ladle casting temperature drop according to any one of claims 1 to 5, characterized in that: The nozzles are distributed in a circular shape with the center of the ladle as the center.

7. The method for reducing ladle casting temperature drop according to claim 6, characterized in that: The outlet direction of each nozzle is obliquely downward and forms an angle of 15° to 25° with the vertical direction, and the projection of the outlet direction on the horizontal plane is along the radial direction of the ring and toward the center of the circle.

8. The method for reducing ladle casting temperature drop according to any one of claims 1 to 5, characterized in that: After the powder spraying device sprays a corresponding amount of ladle covering agent into the current ladle, it also includes: Detecting the spreading state of the ladle covering agent on the slag surface; If the ladle covering agent is not fully spread on the slag surface, the nozzle corresponding to the position not covered by the ladle covering agent is controlled to continue spraying the ladle covering agent until the ladle covering agent is fully spread on the slag surface.

9. The method for reducing ladle casting temperature drop according to claim 8, characterized in that: The nozzle is rotatably provided on the refining furnace cover. When the ladle covering agent is not fully spread on the slag surface, the angle of the nozzle closest to the position not covered by the ladle covering agent is adjusted to face the position not covered by the ladle covering agent and continue to spray the ladle covering agent.

10. A refining furnace used in the method for reducing ladle casting temperature drop according to any one of claims 1 to 9, characterized in that: include: A refining furnace body, wherein the top of the refining furnace body is open; A refining furnace cover, arranged at the opening; A powder spraying device is arranged on the refining furnace cover, and the powder spraying device comprises at least one circle of nozzles distributed in a circular ring shape, and a plurality of nozzles in each circle are evenly distributed along the circumferential direction.

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