A sand drainage device and a method for improving the cleanliness of molten steel

Abstract

The present application relates to the technical field of steelmaking, and provides a drainage sand feeding device and a method for improving the cleanliness of molten steel, which comprises a conduit and a filling body, the conduit is suitable for guiding the drainage sand into a ladle, the filling body is arranged in the conduit, and a gap is formed between the filling body and the inner wall of the conduit, and the filling body is made of a material with a melting point higher than that of the molten steel.The drainage sand feeding device provided by the present application has the following advantages: when the drainage sand is injected into the ladle through the conduit, the drainage sand is filled in the gap between the filling body and the inner wall of the conduit; since the filling body occupies part of the space in the conduit, the filling amount of the drainage sand is reduced, and the cost is saved; since the amount of the drainage sand entering the molten steel is reduced, the cleanliness of the molten steel is improved.

Description

Technical Field

[0001] This invention belongs to the field of steelmaking technology, specifically relating to a device for discharging diverting sand and a method for improving the cleanliness of molten steel. Background Technology

[0002] The purity of steel has become a bottleneck in the production of high-end metallurgical products, thus receiving increasing attention in the steel industry. Many crucial process nodes in steelmaking significantly impact the cleanliness of molten steel. For example, non-steady-state processes during continuous casting can lead to decreased steel cleanliness, especially after the initial pouring of the casting sand into the tundish. This introduces inclusions into the tundish steel. Furthermore, since the main component of the casting sand is oxides, it reacts with [Al] in the molten steel to form Al2O3 inclusions. These inclusions are difficult to remove in subsequent processes, remaining in the steel and ultimately becoming harmful inclusions that affect the quality and performance of the finished product. Therefore, reducing the amount of casting sand used can improve steel cleanliness and reduce production costs. Summary of the Invention

[0003] This invention provides a device for discharging diverting sand and a method for improving the cleanliness of molten steel, thereby improving the cleanliness of molten steel and reducing production costs.

[0004] The present invention also provides a method for improving the cleanliness of molten steel.

[0005] In a first aspect of the present invention, a sand-dispensing device is provided, comprising:

[0006] The catheter is suitable for guiding drainage sand into the ladle;

[0007] A filler is disposed inside a conduit, and there is a gap between the filler and the inner wall of the conduit; the filler is a material with a melting point higher than that of molten steel.

[0008] According to an embodiment of the present invention, a switch is provided at the end of the conduit, the switch being adapted to control the dropping and outflow of the filling material and drainage sand inside the conduit.

[0009] According to the present invention, the material of the diversion sand dispensing device includes either magnesium oxide or aluminum oxide, and the material of the filler can also be other high-melting-point materials that do not easily react with steel.

[0010] According to an embodiment of the present invention, the drainage sand delivery device has a cylindrical filling material; the height of the conduit is greater than two-thirds of the height of the filling material.

[0011] According to an embodiment of the present invention, the difference between the inner diameter of the conduit and the outer diameter of the filler is between five and ten millimeters.

[0012] According to an embodiment of the present invention, the sand-discharging device further includes a feed funnel connected to the first end of the conduit.

[0013] In a second aspect of the invention, a method for improving the cleanliness of molten steel is provided, based on the above-described diversion sand dispensing device, comprising:

[0014] During hot repair of the ladle, filler is placed in the conduit of the sand-draining device;

[0015] Add diversion sand into the diversion sand dispensing device;

[0016] The filler and diverting sand are delivered into the ladle water inlet and the cavity of the seat brick using the diverting sand delivery device.

[0017] A method for improving the cleanliness of molten steel according to an embodiment of the present invention includes:

[0018] When the ladle is started to pour, the slide plate of the ladle opens, and the filler and the diverting sand fall into the tundish. The filler naturally floats to the slag layer.

[0019] According to an embodiment of the present invention, a method for improving the cleanliness of molten steel is provided with a guide surface at the top nozzle of the ladle, the guide surface being adapted to guide the guiding sand and the filler into the interior of the top nozzle of the ladle.

[0020] According to an embodiment of the present invention, in a method for improving the cleanliness of molten steel, the difference between the outer diameter of the filler and the inner diameter of the ladle nozzle is between ten and thirty millimeters.

[0021] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0022] Because the filler is located inside the conduit, when the guide sand is injected into the ladle through the conduit, the guide sand fills the gap between the filler and the inner wall of the conduit. Since the filler occupies part of the space inside the conduit, the amount of guide sand required is reduced, thus saving costs. Furthermore, the reduced amount of guide sand entering the molten steel improves the purity of the molten steel.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a three-dimensional structural schematic diagram of the sand-discharging device provided in an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the ladle outlet structure provided in an embodiment of the present invention.

[0027] Figure label:

[0028] 100. Sand feeding device; 110. Conduit; 120. Filler; 130. Switch; 140. Feed hopper;

[0029] 200, Water inlet; 210, Water inlet inner control cavity; 220, Guide surface; 230, Ladle outlet seat brick. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] Furthermore, the present invention may repeat reference numerals and / or reference letters in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0032] According to a first aspect of the present invention, a sand-dispensing device 100 is provided. Please refer to [link to relevant documentation]. Figure 1 It includes a conduit 110 and a filler 120. The conduit 110 is suitable for guiding the diversion sand to the ladle water inlet 200. The filler 120 is disposed inside the conduit 110, and there is a gap between the filler 120 and the inner wall of the conduit 110. The filler 120 is a material with a melting point higher than that of molten steel.

[0033] Since the filler 120 is located inside the guide tube 110, when the guiding sand is injected into the ladle top nozzle 200 through the guide tube 110, the guiding sand fills the gap between the filler 120 and the inner wall of the guide tube 110. Since the filler 120 occupies part of the space inside the guide tube 110, the amount of guiding sand is reduced, thus saving costs. Since the amount of guiding sand entering the molten steel is reduced, the purity of the molten steel is improved.

[0034] Understandably, during hot repairs of the ladle, filler 120 is added to the guide pipe 110, and then diverting sand is injected into the ladle's top nozzle 200 through the guide pipe 110. When the ladle is opened for casting, after the slide gate is opened, the filler 120 and diverting sand fall into the tundish under their own weight. The filler naturally floats to the slag layer, thereby reducing impurities in the molten steel and improving its purity. The filler 120 is a material with a melting point higher than that of molten steel and does not react with molten steel. Therefore, when the filler 120 falls into the molten steel, it will not contaminate the molten steel by reacting with it.

[0035] In one embodiment, the filler 120 is made of either magnesium oxide or aluminum oxide. Both magnesium oxide and aluminum oxide have good heat resistance, and their melting points are higher than those of molten steel. Magnesium oxide and aluminum oxide do not react with molten steel upon contact and are not affected by high temperatures to dissolve, which facilitates the separation of the filler 120 from the molten steel and avoids the formation of excessive impurities in the molten steel. Furthermore, both magnesium oxide and aluminum oxide have higher densities than molten steel. Using magnesium oxide or aluminum oxide for the filler 120 allows it to float naturally to the slag surface after falling into the molten steel, further facilitating separation of the filler 120 from the molten steel. Generally, the filler 120 is a solid structure for ease of processing; in other embodiments, the filler 120 can also be a closed hollow structure, which reduces the material content of the filler 120, lowers its overall density, and promotes its floating after falling into the molten steel. Of course, in other embodiments, the filler 120 can be made of other materials, as long as the melting point of the filler 120 is higher than that of molten steel and does not react with molten steel.

[0036] In one embodiment, see Figure 1 A switch 130 is provided at the end of the conduit 110. The switch 130 is used to control the flow rate of the fluid inside the conduit 110. The switch 130 facilitates the control of the flow of the filler 120 and the drainage sand. During hot repair of the ladle, the switch 130 of the conduit 110 is closed, the filler 120 is placed into the conduit 110, and then the drainage sand is injected; the conduit 110 is then opened, allowing the filler 120 to be placed into the ladle inlet 200 and the ladle seat brick 230 above it. The switch 130 can be a mechanical switch or an electrical switch. The specific structure of the switch 130 is not particularly limited in this embodiment of the invention.

[0037] In one embodiment, the filler 120 is cylindrical; the height of the conduit 110 is greater than two-thirds of the height of the filler 120. This allows the filler 120 to occupy space within the conduit 110, reducing the amount of drainage sand used. Simultaneously, it prevents the filler 120 from completely filling the conduit 110, reserving space for the injection of drainage sand.

[0038] In one embodiment, the difference between the inner diameter of the conduit 110 and the outer diameter of the filler 120 is between five and ten millimeters, which facilitates the formation of a gap between the filler 120 and the inner wall of the conduit 110, making it easier to fill with drainage sand. For example, the difference between the inner diameter of the conduit 110 and the outer diameter of the filler 120 can be five millimeters.

[0039] In one embodiment, the sand dispensing device 100 further includes a feed funnel 140, which is connected to the head end of the conduit 110 to facilitate the injection of sand into the conduit 110.

[0040] In a second aspect of the invention, a method for improving the cleanliness of molten steel is provided, based on the aforementioned guide sand dispensing device 100, comprising the following steps:

[0041] During hot repair of the ladle, filler 120 is placed in the conduit 110 of the sand delivery device 100;

[0042] Diverting sand is added to the diverting sand dispensing device 100;

[0043] The filler 120 and the diverting sand are fed into the ladle inlet 200 by the diverting sand dispensing device 100.

[0044] By placing a filler 120 inside the conduit 110, the amount of diversion sand used can be reduced, thereby reducing costs and impurities in the molten steel, thus improving the purity of the molten steel.

[0045] In one embodiment, it includes:

[0046] When the ladle is started to pour, the slide plate of the ladle top nozzle 200 opens, and the filler 120 and the diversion sand fall into the tundish. After that, the filler 120 naturally floats to the surface of the slag.

[0047] When the ladle is poured, the slide plate of the ladle top nozzle 200 opens, and the filler 120 and the guide sand fall into the tundish. After the molten steel is poured, because the filler 120 has a low density, it floats on the slag surface. Compared with the traditional method of using guide sand to introduce all the molten steel, this embodiment of the invention can reduce impurities in the molten steel and improve the purity of the molten steel.

[0048] In one embodiment, see Figure 2The ladle inlet 200 is provided with a guide surface 220, which is suitable for guiding the diversion sand and filler 120 into the interior of the ladle inlet 200, which is beneficial for putting the diversion sand and filler 120 into the ladle inlet 200.

[0049] In one embodiment, the difference between the outer diameter of the filler 120 and the inner diameter of the ladle inlet 200 is between ten and thirty millimeters to prevent the filler 120 from getting stuck in the inlet 200 due to the small diameter of the ladle inlet 200. For example, the difference between the outer diameter of the filler 120 and the inner diameter of the ladle inlet 200 can be ten millimeters.

[0050] The embodiments of the present invention are applicable to the field of continuous casting, and can also be applied to die casting or other related technical fields.

[0051] Example 1

[0052] Taking a 200t steel ladle as an example, the inner diameter of the ladle's top inlet 200 is 80 mm, and the outer diameter is 240 mm. The inner diameter of the top of the ladle's top inlet 200 is chamfered at 45 degrees to the outer surface, and its height is 360 mm. The height from the top of the top inlet 200 to the bottom of the ladle's top inlet 200 is 220 mm. The filler 120 is made of magnesium oxide and is cylindrical with a diameter of 70 mm and a length of 430 mm. The diversion sand feeding device 100 consists of a feed funnel 140, a guide pipe 110, and a switch 130. The guide pipe 110 has a diameter of 75 mm and a length of 300 mm, and its effective volume is the same as the total volume of the original diversion sand only.

[0053] During hot repair of the ladle, filler 120 is placed at the bottom of the guide tube 110 of the sand-discharging device 100, and then sand-discharging material is added to the sand-discharging device 100. The sand-discharging device 100 is moved above the outlet of the ladle's water inlet 200, with the guide tube 110 aligned with the center of the outlet of the ladle's water inlet 200. The switch 130 of the guide tube 110 is opened, and filler 120 slides down to the bottom of the ladle's water inlet 200. The sand-discharging material forms a sand dune shape inside the cavity at the top of the ladle's seat brick 230. The ladle receives molten steel of pipeline steel X80, with a process route of BOF-LF-VD-CC. After VD vacuum refining, the ladle is hoisted to the ladle turret. When pouring begins, the slide plate is opened, and filler 120 and sand-discharging material fall into the tundish under their own weight. Filler 120 naturally floats to the slag surface.

[0054] The amount of diverting sand was reduced by 1.65 liters. During the non-steady-state casting period, the steel billets were rolled and then the steel was graded for inclusions. The pass rate for all types of inclusions graded ≤1.5 was 99.4%.

[0055] Example 2

[0056] Taking a 210t steel ladle as an example, the inner diameter of the inlet 200 is 80 mm, and the outer diameter is 240 mm. The inner diameter of the inlet 200 is chamfered at 60 degrees to the outer surface, and the height is 365 mm. The height from the top of the inlet 200 to the bottom is 215 mm. The filler 120 is made of magnesium oxide and is cylindrical with a diameter of 50 mm and a length of 480 mm. The diversion sand feeding device 100 consists of a feed funnel 140, a guide pipe 110, and a switch 130. The guide pipe 110 has a diameter of 55 mm and a length of 420 mm, and its effective volume is the same as the total volume of the original diversion sand only.

[0057] During hot repair of the ladle, filler 120 is placed at the bottom of the guide pipe 110 at the lower end of the sand-feeding device 100, and then sand-feeding material is added to the sand-feeding device 100. The sand-feeding device 100 is moved above the outlet of the ladle's water inlet 200, with the guide pipe 110 aligned with the center of the outlet. The switch 130 is opened, and filler 120 slides down to the bottom of the ladle's water inlet 200. The sand-feeding material forms a sand dune shape inside the cavity at the top of the ladle's seat brick 230. The ladle receives molten steel of pipeline steel X70, with a process route of BOF-LF-RH-CC. After RH vacuum refining, the ladle is hoisted to the ladle turret. When pouring begins, the slide plate is opened, and filler 120 and sand-feeding material fall into the tundish under their own weight. Filler 120 naturally floats to the slag surface.

[0058] The amount of diverting sand was reduced by 0.94 liters. During the non-steady-state casting period, the steel billets were rolled and then the steel was graded for inclusions. The pass rate for all types of inclusions graded ≤1.5 was 99.1%.

[0059] Example 3

[0060] Taking a 100t steel ladle as an example, the inner diameter of the inlet 200 is 70 mm and the outer diameter is 190 mm. The inner diameter of the inlet 200 is chamfered at 50 degrees to the outer surface, and the height is 350 mm. The height from the top of the inlet 200 to the bottom is 245 mm. The filler 120 is cylindrical, made of magnesium oxide, with a diameter of 50 mm and a length of 490 mm. The guide tube 110 of the diversion sand feeding device 100 has a diameter of 55 mm and a length of 420 mm, and its effective volume is the same as the total volume of the original diversion sand only.

[0061] During hot repair of the ladle, a cylindrical packing material 120 is placed at the bottom of the guide pipe 110 of the diversion sand feeding device 100, and diversion sand is then added to the diversion sand feeding device 100. The diversion sand feeding device 100 is moved above the outlet of the ladle's water inlet 200, with the guide pipe 110 aligned with the center of the outlet. The switch 130 is opened, and the packing material 120 slides down to the bottom of the ladle's water inlet 200. The diversion sand forms a sand dune shape inside the cavity at the top of the ladle's seat brick 230. The ladle receives molten steel, the steel grade being marine engineering steel E690, and the process route is BOF-LF-RH-in-sink casting, after which RH vacuum refining is completed. The ladle is then opened for pouring, the slide plate is opened, and the packing material 120 and the diversion sand fall into the tundish under their own weight. The packing material 120 naturally floats to the slag surface.

[0062] The amount of diverting sand was reduced by 0.96 liters. During the non-steady-state casting period, the steel was graded for inclusions after the ingots were rolled. The pass rate for all types of inclusions with a grade of ≤1.5 was 99.7%.

[0063] Comparative Example

[0064] A 200t steel ladle is used. The inner diameter of the ladle's inlet is 80 mm, the outer diameter is 240 mm, the height is 360 mm, and the height from the top of the inlet to the bottom of the ladle is 220 mm.

[0065] During hot repairs of the ladle, diversion sand is added to fill the bottom surface of the ladle base bricks, forming a sand dune. The ladle receives molten steel, specifically pipeline steel X80, following the BOF-LF-VD-CC process. After VD vacuum refining, the ladle is hoisted to the ladle turret. When pouring begins, the slide gate is opened, and the diversion sand falls into the tundish under its own weight.

[0066] The amount of diversion sand used was 14.15 liters. During the non-steady-state casting period, the steel billets were rolled and the steel was graded for inclusions. The pass rate for various inclusions graded ≤1.5 was 92.2%.

[0067] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0068] It should be noted that all directional indications in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0069] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0070] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "multiple" means two or more, unless otherwise explicitly specified.

[0071] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for improving the cleanliness of molten steel, comprising a sand-feeding device, characterized in that, The sand delivery device includes: The catheter is suitable for guiding drainage sand into the ladle; A filler is disposed inside a conduit, and there is a gap between the filler and the inner wall of the conduit. Drainage sand fills the gap between the filler and the inner wall of the conduit. The filler is a material with a melting point higher than that of molten steel. The filler material includes either magnesium oxide or aluminum oxide; The method includes: During hot repair of the ladle, filler is placed in the conduit of the sand-draining device; Add diversion sand into the diversion sand delivery device; The filler and diversion sand are fed into the ladle water inlet using the diversion sand dispensing device; When the ladle is started to pour, the slide plate of the ladle opens, and the filler and the diverting sand fall into the tundish. The filler naturally floats to the slag layer.

2. The method for improving the cleanliness of molten steel according to claim 1, characterized in that, A switch is provided at the end of the catheter, which is used to control the discharge of the filler and drainage sand inside the catheter.

3. The method for improving the cleanliness of molten steel according to any one of claims 1 to 2, characterized in that, The filler is cylindrical; the height of the conduit is greater than two-thirds of the height of the filler.

4. The method for improving the cleanliness of molten steel according to any one of claims 1 to 2, characterized in that, The difference between the inner diameter of the catheter and the outer diameter of the filler is between five and ten millimeters.

5. The method for improving the cleanliness of molten steel according to any one of claims 1 to 2, characterized in that, The sand delivery device also includes a feed funnel, which is connected to the beginning of the guide tube.

6. The method for improving the cleanliness of molten steel according to claim 1, characterized in that, The ladle inlet is provided with a guide surface, which is suitable for guiding the diversion sand and the filler into the interior of the ladle inlet.

7. The method for improving the cleanliness of molten steel according to claim 1, characterized in that, The difference between the outer diameter of the filler and the inner diameter of the ladle water inlet is between ten and thirty millimeters.

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