Cover device, and method for treating molten steel

Abstract

Embodiments of the present invention relate to a cover device which can open / close the opening of a ladle capable of accommodating molten steel, and which may comprise: a cover member which can be supported on or separated from the ladle such that the opening of the ladle can be opened and closed; and a protruding member extending downward from the lower surface of the cover member so as to be immersed in a slag layer floating on the molten steel. Therefore, according to embodiments of the present invention, an operation of destroying a solidified slag layer prior to a refining operation can be omitted. In addition, even if the operation of destroying the solidified slag layer is performed as necessary, the solidified slag layer can be more easily and more quickly destroyed than that destroyed by a conventional device. Therefore, refining operation time is shortened.

Description

Cover device and molten steel processing method

[0001] The present invention relates to a cover device and a method for treating molten steel, and more specifically, to a cover device capable of closing a ladle containing molten steel and a method for treating molten steel.

[0002] When molten metal (hereinafter referred to as molten steel) is produced in an electric furnace device, the molten steel is loaded into a ladle. Then, after moving the ladle containing the molten steel to a refining operation, the molten steel is heated using a heating device. That is, after lowering the electrode rod of the heating device into the ladle, power is applied to the electrode rod, and the molten steel is heated using the arc heat generated from the electrode rod. At this time, in order for the molten steel to be heated by the arc heat generated from the electrode rod, the upper surface (molten steel surface) of the molten steel facing the electrode rod must be exposed.

[0003] However, the temperature of the molten steel drops while the ladle is being transported to the refining facility. Consequently, the slag floating on top of the molten steel solidifies, forming a solidified slag layer on the upper surface. Therefore, the solidified slag layer must first be crushed to expose the upper surface of the molten steel. Then, the electrode rod is lowered so that its lower end faces the upper surface of the molten steel. In other words, the process of destroying the solidified slag layer must be performed beforehand to heat the molten steel. Consequently, there is a problem in that the time required for molten steel refining increases.

[0004] (Prior Art Literature) (Patent Literature 1) Korean Registered Patent 10-1243215

[0005] The present invention provides a cover device and a method for treating molten steel that allow the work of destroying the slag solidification layer to be omitted.

[0006] The present invention provides a cover device capable of forming a slag solidification layer that is easy to break, and a method for treating molten steel.

[0007] An embodiment of the present invention may include a cover device capable of opening and closing an opening of a ladle capable of receiving molten steel, comprising: a cover member that is supported on or can be separated from the ladle to open and close the opening of the ladle; and a protruding member extending downward from the lower surface of the cover member so as to be immersed in a slag layer floating above the molten steel.

[0008] The above protruding member can be fixed to the lower surface of the cover member.

[0009] The above-mentioned protruding member may include a refractory member manufactured from a raw material containing refractory material.

[0010] The above-mentioned protruding member is disposed on the inner side of the above-mentioned refractory member and includes a support member made of a material containing metal, and the above-mentioned refractory member may be disposed to surround the outer surface of the support member.

[0011] The lower region of the above-mentioned protruding member may have a shape in which the width decreases as it goes downward.

[0012] The above protruding member may be positioned at the horizontal center of the cover member.

[0013] The position of the above-mentioned protruding member can be installed to be the same as the horizontal position of the electrode rod of the heating device that can be placed in the ladle.

[0014] The above protruding members may include a plurality of them.

[0015] It may include a guide member extending downward from the edge of the above cover member.

[0016]

[0017] A method for treating molten steel according to an embodiment of the present invention may include: a process of charging molten steel into the internal space of a ladle; a process of placing a cover member over the opening of the ladle to close the opening, and immersing a protruding member extending downward from the lower surface of the cover member into a slag layer floating on the upper surface of the molten steel; and a process of transporting the ladle to a destination for a refining operation.

[0018] While conveying the above ladle, the temperature of the molten steel and slag layer decreases, causing the slag layer to solidify, and the slag layer may solidify while the protruding member is immersed.

[0019] When immersing the above-mentioned protruding member in the slag layer, it can be immersed so as to be positioned at the horizontal center of the ladle.

[0020] In immersing the above-mentioned protruding member in the slag layer, the protruding member can be immersed in the molten steel contained in the ladle such that it is positioned at the same horizontal position as the electrode rod in the subsequent refining operation.

[0021] A method for treating molten steel according to an embodiment of the present invention may include: a process of stopping the transfer of the ladle when the ladle arrives at the destination; a process of separating the cover member from the ladle to open the opening of the ladle, separating the protruding member from the slag solidification layer in which the slag layer has solidified, and forming an opening in which the molten steel is exposed to the slag solidification layer; and a process of refining the molten steel using the opening.

[0022] The process of refining the molten steel may include: a process of lowering the electrode rod to pass through the opening so that the upper surface of the exposed molten steel and the lower end of the electrode rod face each other; and a process of heating the molten steel by applying power to the electrode rod.

[0023] The process of refining the molten steel may include: a process of breaking the slag layer from the region surrounding the opening in the slag solidification layer; a process of lowering the electrode rod so that the upper surface of the molten steel and the lower end of the electrode rod face each other; and a process of applying power to the electrode rod to heat the molten steel.

[0024] The process of refining the molten steel may include: a process of lowering the electrode rod toward the opening to break the slag solidification layer around the opening; a process of further lowering the electrode rod so that the upper surface of the molten steel and the lower end of the electrode rod face each other; and a process of applying power to the electrode rod to heat the molten steel.

[0025] According to embodiments of the present invention, the operation of breaking the slag solidification layer before the refining operation can be omitted. Furthermore, even if the operation of breaking the slag solidification layer is performed as necessary, it can be broken more easily and quickly compared to conventional methods. Therefore, there is an effect of shortening the refining operation time.

[0026] FIG. 1 is a front view illustrating a ladle supported on a trolley, in a state where the ladle is closed using a cover device according to an embodiment of the present invention.

[0027] FIG. 2 is a front cross-sectional view illustrating a state in which a ladle is closed using a cover device according to an embodiment of the present invention.

[0028] FIG. 3 is a plan view of a cover device according to an embodiment of the present invention, viewed from the bottom.

[0029] FIG. 4 is a front cross-sectional view showing a heating device placed over a ladle opening.

[0030] Figure 5 is a top view of the heating device.

[0031] Figure 6 (a) is an enlarged view showing the state in which a protruding member penetrates the slag solidification layer when the cover device closes the opening of the ladle.

[0032] Figure 6(b) is an enlarged view showing the state in which an opening is formed in the slag solidification layer when the cover device is separated from the ladle and the opening is opened.

[0033] Figure 6 (c) is an enlarged view showing the state in which the opening of the ladle is closed using a heating device.

[0034] Hereinafter, embodiments of the present invention will be described in more detail with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms; these embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. To illustrate embodiments of the present invention, the drawings may be exaggerated, and like reference numerals in the drawings refer to like components.

[0035] FIG. 1 is a front view illustrating a ladle supported on a trolley being closed using a cover device according to an embodiment of the present invention. FIG. 2 is a front cross-sectional view illustrating a ladle being closed using a cover device according to an embodiment of the present invention. FIG. 3 is a plan view of a cover device according to an embodiment of the present invention viewed from below. Here, 2 is a drawing illustrating a state before the slag layer solidifies.

[0036] First, the bogie (200) and ladle (100) will be described with reference to FIGS. 1 and FIGS. 2.

[0037] The trolley (200) can move horizontally and can support the ladle (100). The trolley (200) may include a main body (210), a mounting part (220) connected to the main body (210) to support the ladle (100), and a driving part (230) connected to the main body (210) to move the main body (210) horizontally.

[0038] The main body (210) may have a larger surface area than the ladle (100). Additionally, a driving unit (230) may be connected to the lower part of the main body (210). The driving unit (230) may include, for example, a wheel. The mounting unit (220) may extend upward from the main body (210). A groove may be provided on the upper part of the mounting unit (220) to support or mount a part of the ladle (100).

[0039] The ladle (100) has an internal space capable of accommodating molten steel (M) and may be in the shape of a tubular opening at the top. Hereinafter, the opening formed at the top of the ladle (100) is referred to as the 'opening (110)'.

[0040] The ladle (100) may include a bottom portion (120a) having a predetermined area and a side wall portion (120b) extending upward from the bottom portion (120a). Additionally, the ladle (100) may include a support portion (130) installed on the side wall portion (120b) so as to be supported on a mounting portion (220) of a bogie (200). Furthermore, the ladle (100) may include a fastening portion (140) installed on the side wall portion (120b) so as to be connected to a hook of a hoisting device (not shown).

[0041] The side wall portion (120b) may extend in the perimeter direction of the bottom portion (120a). Each of the bottom portion (120a) and the side wall portion (120b) may include an outer member (121) and an inner member (122) installed on the inner surface of the outer member (121). The outer member (121) may be formed of a material including metal, for example, the outer member (121) may be a steel shell. The inner member (122) may be formed of a material including refractory material.

[0042] Molten steel (M) can be contained within the internal space of the ladle (100), and slag can float on the upper surface of the molten steel (M). The slag can be applied to the entire upper surface of the molten steel (M). For convenience of explanation, a layer consisting of slag having a predetermined area is referred to as a 'slag layer (SL)'. Furthermore, the 'slag layer (SL)' referred to below may mean a liquid state or a state before solidification.

[0043] When molten steel (M) is charged into the internal space of the ladle (100), the slag layer (SL) may be in a liquid state. Subsequently, when the ladle (100) is maintained without heating for a predetermined period of time, the slag layer may solidify. For convenience of explanation, the solidified slag layer (SL) is referred to as the 'solidified slag layer' below.

[0044]

[0045] The cover device (300) can open and close the opening (110) of the ladle (100). That is, the cover device (300) can be supported on the upper part of the ladle (100) so as to close the opening (110) of the ladle (100). More specifically, the cover device (300) can close the opening (110) of the ladle (100) so as to suppress or prevent molten steel (M) and slag layer (SL) from being exposed to the outside air. Additionally, the cover device (300) can be separated from the ladle (100), thereby allowing the opening (110) of the ladle (100) to be opened.

[0046] Referring to FIGS. 1 to 3, the cover device (300) may include a cover member (310) capable of opening and closing an opening (110) of a ladle (100) and a protruding member (320) extending downward from the lower surface of the cover member (310) so that at least a portion of it may be immersed in a slag layer (SL) contained in the ladle (100).

[0047] Additionally, the cover device (300) may include a guide member (330) extending downward from the edge of the cover member (310) so as to be positioned on the outside of the side wall portion (120b) of the ladle (100), and a hook (340) connected to the upper surface of the cover member (310) to which a hook of a crane capable of transporting the cover device (300) can be attached.

[0048]

[0049] The cover member (310) may be in the shape of a plate having a predetermined area so as to be able to close the opening (110) of the ladle (100). The size of the cover member (310) may be larger than or equal to the opening (110) of the ladle (100). The cover member (310) may have a shape corresponding to that of the ladle (100). For example, the shape of the cross-section of the ladle (100) cut in the horizontal direction may be circular, and the cover member (310) may have a circular plate shape. Of course, the shape of the cover member (310) is not limited to the examples described above, and any shape is acceptable as long as it can close the opening (110) of the ladle (100).

[0050]

[0051] The guide member (330) may extend downward from the cover member (310) so as to be positioned on the outside of the side wall portion (120b) of the ladle (100). For example, the guide member (330) may extend downward from the side of the cover member (310) as shown in FIG. 2. There may be multiple guide members (330), and multiple guide members (330) may be arranged in the circumferential direction of the cover member (310) or the ladle (100) as shown in FIG. 3. Then, when lowering the cover device (300) to the top of the ladle (100), the guide member (330) is positioned on the outside of the side wall portion (120b) of the ladle (100) before lowering. Accordingly, when the cover device (300) is supported on the top of the ladle (100), the cover device (300) can be stably supported.

[0052]

[0053] After closing the opening (110) using the cover device (300), the trolley (200) is moved. That is, the trolley (200) is moved to a location where a refining operation is performed. The refining operation may be, for example, an operation (temperature increase operation) in which molten steel is heated using a heating device.

[0054] Before describing the protruding member (320) of the cover device (300), the heating device (400) will first be described with reference to FIGS. 4 and FIGS. 5.

[0055] FIG. 4 is a front cross-sectional view showing a heating device placed over a ladle opening. FIG. 5 is a top view of the heating device.

[0056] Referring to FIGS. 4 and 5, the heating device (400) may include a closing member (410) capable of closing the opening (110) of the ladle (100) and an electrode rod (420) installed to penetrate the closing member (410) in an upward and downward direction.

[0057] The closing member (410) of the heating device (400) can close the ladle (100) as described above. And, when the closing member (410) closes the ladle (100), the lower part of the electrode rod (420) can be inserted into the interior of the ladle (100). The configuration including the ladle (100) and the heating device (400) may be named a ladle furnace.

[0058] The heating device (400) may include a plurality of electrode rods (420), and the plurality of electrode rods (420) may be positioned at the horizontal center of the closing member (410) as shown in FIG. 5. Additionally, the plurality of electrode rods (420) may be positioned spaced apart by a predetermined distance. The heating device (400) may include, for example, three electrode rods (420), and the arrangement of the three electrode rods (420) may be, for example, a triangle. That is, the shape formed by connecting the width center of each of the three electrode rods (420) may be a triangle. Here, the horizontal direction of the closing member (410) may be the width direction of the closing member (410).

[0059] When the ladle (100) arrives at the location where the heating device (400) is installed, the molten steel is heated using the heating device (400). To do this, the opening (110) of the ladle (100) is closed using the closing member (410) of the heating device (400). Then, a plurality of electrode rods (420) are lowered. Accordingly, the lower portions of the plurality of electrode rods (420) can be positioned inside the ladle (100). At this time, the electrode rods (420) are lowered so that the lower portion (or lower surface) of the electrode rod (420) is positioned between the upper surface of the slag layer or slag solidification layer and the upper surface of the molten steel (M). In other words, the electrode rods (420) are lowered so that the lower portion (or lower surface) of the electrode rod (420) faces the upper surface of the molten steel (M) at an adjacent distance. At this time, the lower part (or lower surface) of the electrode rod (420) can be spaced apart from the upper surface of the molten steel (M).

[0060] Next, when power is supplied to the multiple electrode rods (420), an arc is generated from the multiple electrode rods (420). In order for the molten steel (M) to be heated by the arc and heat generated from the multiple electrode rods (420), the upper surface (molten steel surface) facing the electrode rods (420) needs to be exposed.

[0061] However, when the slag layer is solidified, the upper surface of the molten steel (M) is covered by the solidified slag layer, so even if the electrode rod (420) is lowered into the solidified slag layer, the upper surface of the molten steel is not exposed. In other words, the electrode rod (420) cannot penetrate the solidified slag layer and descend. Consequently, even if an arc and heat are generated from the electrode rod (420), the arc and heat may not be transferred to the molten steel, or the amount transferred may be small. Consequently, the molten steel (M) cannot be easily heated. Therefore, when the slag layer is solidified, the electrode rod (420) is lowered after the solidified slag layer is destroyed to expose the upper surface of the molten steel. Thus, there is a problem in that an additional operation to destroy the solidified slag layer must be performed before the temperature increase operation.

[0062]

[0063] In the embodiment, a protruding member (320) is used to suppress or prevent the entire upper surface of the molten steel (M) from being closed by a slag solidification layer. That is, by using the protruding member (320), a slag solidification layer (SL) in some area of ​​the upper surface of the molten steel (M) S It is possible to prevent ) from being formed.

[0064] The protruding member (320) may have a shape that extends in the vertical direction and may be connected to or fixed to the lower surface of the cover member (310). That is, the protruding member (320) may have a shape that extends downward from the lower surface of the cover member (310). The protruding member (320) may be extended to a length such that at least a portion of it can be immersed in the slag layer (SL) as shown in FIG. 2. That is, as the protruding member (320) extends downward from the lower surface of the cover member (310), it may be extended so that at least a portion of it can be immersed or deposited in the slag layer (SL). Additionally, the protruding member (320) may be extended so that its lower portion can be immersed in the molten steel (M) located below the slag layer (SL).

[0065] The protruding member (320) may be, for example, a cylindrical shape extending in the vertical direction. In other words, the protruding member (320) may have a circular cross-section when cut in the horizontal direction. The lower region of the protruding member (320) may have a shape in which the width decreases toward the lower end (bottom).

[0066] The width (horizontal length) of the protruding member (320) may be equal to or greater than the width of the electrode rod (410) of the heating device (400). In other words, the diameter of the protruding member (320) may be equal to or greater than the diameter of the electrode rod (410).

[0067] The protruding member (320) may include a refractory member (321) formed from a raw material containing refractory material. Additionally, the protruding member (320) may include a support member (322) disposed inside the refractory member (321).

[0068] The support member (322) may be extended in the vertical direction, and its upper portion may be fixed to the lower surface of the cover member (310). The support member (322) may be manufactured from a material including metal. For example, the support member (322) may be an iron core.

[0069] The refractory member (321) may be installed to surround the outer surface of the support member (322). More specifically, the refractory member (321) may surround the side and bottom surfaces of the support member (322), and the upper surface of the support member (322) may be connected to the lower surface of the cover member (310). Additionally, the lower region of the refractory member (321) may have a shape in which the width decreases toward the lower end (bottom).

[0070] The refractory member (321) is manufactured using raw materials containing refractory material as described above. Accordingly, damage to the refractory member (321) by the heat of the molten steel (M) and slag layer (SL) can be suppressed or prevented. Additionally, the refractory member (321) is installed to surround the outer surface of the support member (322), and the support member (322) is fixed to the lower surface of the cover member (310). Accordingly, the refractory member (321) can be fixed without being separated from the cover member (310). In other words, the support member (322) can suppress or prevent the refractory member (321) from being separated from the cover member (310).

[0071]

[0072] The protruding member (320) may be positioned at the horizontal center of the ladle (100) or at the horizontal center of the opening (110) of the ladle (100). Additionally, the protruding member (320) may be positioned at the horizontal center of the cover member (310) as shown in FIGS. 2 and 3. Here, the horizontal direction of the ladle (100), the horizontal direction of the opening (110) of the ladle (100), and the horizontal direction of the cover member (310) may refer to the width direction of the ladle (100), the opening (110), and the cover member (310), respectively.

[0073] And the position of the protruding member (320) may be the same as the horizontal position of the electrode rod (420) of the heating device (400). In other words, the position of the protruding member (320) on the opening (110) of the ladle (100) may be the same as the position of the electrode rod (420) of the heating device (400). That is, the position of the protruding member (320) and the position of the electrode rod (420) on the opening (110) of the ladle (100) may be the same. In other words, when fixing the protruding member (320) to the lower surface of the cover member (310), the protruding member (320) is fixed so that its position on the opening (110) of the ladle (100) may be the same as the position of the electrode rod (420).

[0074] The cover device (300) may include a plurality of protruding members (320). The cover device (300) may include a number of protruding members (320) equal to the number of electrode rods (420) included in the heating device (400). For example, the heating device (400) may include three electrode rods (420). Accordingly, the cover device (300) may include three protruding members (320) as shown in FIGS. 2 and FIGS. 3. Each of the plurality of protruding members (320) may be fixed to the lower surface of the cover member (310), and the plurality of protruding members (320) may be spaced apart from each other. The plurality of protruding members (320) may be positioned at the horizontal center of the cover member (310) as shown in FIGS. 2 and FIGS. 3.

[0075] Additionally, the plurality of protruding members (320) may be arranged in the same form as the arrangement of the plurality of electrode rods (420). Additionally, the spacing between the plurality of electrode rods (420) may be arranged at the same spacing as the spacing between the plurality of electrode rods (420) of the heating device. Furthermore, the position of the plurality of protruding members (320) on the opening (110) of the ladle (100) may be the same as the position of the plurality of electrode rods (420). That is, the position of the plurality of protruding members (320) and the position of the plurality of electrode rods (420) on the opening (110) of the ladle (100) may be the same. In other words, when fixing the plurality of protruding members (320) to the lower surface of the cover member (310), the position of the plurality of protruding members (320) on the opening (110) of the ladle (100) is fixed so that the position of the plurality of protruding members (320) is the same as the position of the plurality of electrode rods (420).

[0076]

[0077] FIG. 6(a) is an enlarged view showing a state in which a protruding member penetrates the slag solidification layer when the cover device closes the opening of the ladle. FIG. 6(b) is an enlarged view showing a state in which an opening is formed in the slag solidification layer when the cover device is separated from the ladle and the opening is opened. FIG. 6(c) is an enlarged view showing a state in which the opening of the ladle is closed using a heating device. Here, FIG. 6(a) to (c) show the state in which the slag layer has solidified (slag solidification layer).

[0078] When molten steel (M) is loaded into the ladle (100), the opening (110) of the ladle (100) is closed using the cover device (300). At this time, since the slag layer (SL) has not yet solidified, the lower part of the protruding member (320) can penetrate into the slag layer (SL) as shown in FIG. 2.

[0079] And, after a predetermined time has elapsed, the temperature of the molten steel (M) and the slag layer (SL) may decrease, and the slag layer (SL) may solidify. At this time, the slag layer (SL) solidifies while the lower part of the protruding member (320) has penetrated into the slag layer (SL). Accordingly, as shown in FIG. 6 (a), the protruding member (320) is in the slag solidification layer (SL S ) penetrating or slag solidification layer (SL S It can be in a state where it is inserted as ). In other words, in the area of ​​the upper surface of the molten steel (M) that does not face the protruding member (320), a slag solidification layer (SL S ) exists, and in the area facing the protruding member (320), a slag solidification layer (SL) S ) may not exist. In other words, the slag solidification layer (SL S ) may be discontinuous rather than continuous in the horizontal direction.

[0080] Accordingly, when the cover device (300) is raised to open the opening (110) of the ladle (100), an opening (OP) can be formed at the location where the protruding member (320) was inserted, as shown in FIG. 6 (b). Accordingly, the area of ​​the upper surface of the molten steel (M) that does not face the opening (OP) is a slag solidification layer (SL S It is covered by ), and the area facing the opening (OP) is a slag solidification layer (SL S It can be exposed to the outside of ).

[0081] In addition, the slag solidification layer (SL S The position of the opening (OP) of ) may be the same as the position of the electrode rod (420). That is, the slag solidification layer (SL) on the upper surface of the molten steel (M) S The position of the opening (OP) of the ladle (100) may be the same as the position of the electrode rod (420) on the upper surface of the molten steel (M) when the heating device (400) closes the opening (110) of the ladle (100). Accordingly, when the opening of the ladle (100) is closed by the heating device (400), the electrode rod (420) and the slag solidification layer (SL S The opening (OP) of ) can face each other. Therefore, as shown in (c) of FIGS. 4 and 6, the electrode rod (420) is in the slag solidification layer (SL S It can descend to pass through the opening (OP) of ). That is, the slag solidification layer (SL S Without performing a separate operation to destroy the (), the lower part or lower surface of the electrode rod (420) can be positioned to face the upper surface of the molten steel. Therefore, the molten steel (M) can be easily heated using the arc generated from the electrode rod (420).

[0082]

[0083] Hereinafter, with reference to FIGS. 1 to 5 and FIGS. 6 (a) to (c), a method of moving a ladle (100) to a refining operation facility while the ladle is closed using a cover device (300) according to an embodiment of the present invention will be described.

[0084] When molten steel is produced in an electric furnace, the molten steel (M) is loaded into the internal space of a ladle (100). Then, as shown in FIG. 1, the ladle (100) is supported on a trolley (200). Next, as shown in FIG. 2, the opening (110) of the ladle (100) is closed using a cover device (300). More specifically, the hook of a crane is attached to the hook (340) of the cover device (300). Then, the cover device (300) is moved to the upper side of the ladle (100) using a crane, and then the cover device (300) is lowered to the upper side of the ladle (100). That is, the cover device (300) is lowered so that the edge of the lower surface of the cover member (310) can come into contact with the upper side of the ladle (100). Additionally, the cover device (300) is lowered so that the cover member (310) faces the opening (110) of the ladle (100) and the guide member (330) is positioned on the outside of the side wall (120b) of the ladle (100). At this time, the cover device (300) can be lowered so that the guide member (330) can descend along the outer surface of the side wall (120b) of the ladle (100). Accordingly, the cover device (300) can be stably supported on the upper part of the ladle (100).

[0085] When the opening (110) of the ladle (100) is closed by the cover device (300), each of the plurality of protruding members (320) can be immersed in the slag layer (SL) as shown in FIG. 2. At this time, the plurality of protruding members (320) can be immersed so as to be positioned at the horizontal center of the upper surface of the molten steel (M). Additionally, each of the plurality of protruding members (320) can be immersed so as to come into contact with the molten steel (M) located at the bottom of the slag layer (SL).

[0086] When the opening (110) of the ladle (100) is closed by the cover device (300), the ladle (100) is moved for a refining operation. That is, the trolley (200) on which the ladle (100) is supported is moved. The refining operation may be, for example, an operation to heat molten steel (M) to raise its temperature (temperature raising operation). Accordingly, the destination to which the ladle (100) is to be moved may be a location where a heating device (400) is installed.

[0087] While moving the ladle (100) to a destination, the temperature of the molten steel (M) and slag layer (SL) contained in the ladle (100) may decrease. That is, even if the ladle (100) is moved with the opening (110) closed using the cover device (300), the temperature of the molten steel (M) and slag layer (SL) may decrease because the ladle (100) is not being heated. Consequently, the slag layer (SL) may solidify.

[0088] However, in the embodiment, the protruding member (320) was immersed in the slag layer (SL) before the slag layer (SL) solidified. Accordingly, the slag layer (SL) can solidify while the protruding member (320) is inserted into the slag layer (SL). As a result, slag may not exist in the area facing the protruding member (320) on the entire upper surface of the molten steel (M). In other words, slag may exist in the area of ​​the upper surface of the molten steel (M) excluding the area facing the protruding member (320). Therefore, the slag solidification layer (SL) S ) may be formed discontinuously rather than continuously in the horizontal direction. That is, as shown in FIG. 6 (a), in the area of ​​the upper surface of the molten steel (M) that does not face the protruding member (320), a slag solidification layer (SL) S ) exists, and in the area facing the protruding member (320), a slag solidification layer (SL) S ) may not exist.

[0089] When the ladle (100) reaches the destination, the cover device (300) is raised as in FIG. 6(b) to open the opening (110) of the ladle (100). At this time, an opening (OP) may be formed at the location where the protruding member (320) was inserted. That is, the area of ​​the upper surface of the molten steel (M) that does not face the opening (OP) is a slag solidification layer (SL S It is covered by ), and the area facing the opening (OP) is a slag solidification layer (SL S It can be exposed to the outside of ).

[0090] Next, the molten steel (M) is heated using a heating device (400). To do this, the opening (110) of the ladle (100) is closed using a closing member (410) of the heating device (400) as shown in (c) of FIGS. 4 and 6. At this time, since a plurality of electrode rods (420) are penetrating the closing member (410), the lower portion of each of the plurality of electrode rods (420) can be inserted into the interior of the ladle (100). In addition, each of the plurality of electrode rods (420) is a slag solidification layer (SL S It can face multiple openings (OP) of ). Next, the multiple electrode rods (420) are lowered so that the lower ends of the multiple electrode rods (420) as in (c) of FIGS. 4 and 6 are facing the slag solidification layer (SL S Inserted into the opening (OP) of the electrode rod. At this time, the lower surface of the plurality of electrode rods (420) is lowered so that it is spaced apart from the upper surface of the molten steel by a predetermined distance. When the plurality of electrode rods (420) are lowered, the lower end or lower surface of the plurality of electrode rods (420) can face the upper surface of the molten steel.

[0091] Thus, according to an embodiment of the present invention, the slag solidification layer (SL S Without performing a separate operation to destroy the electrode rod (420), the lower end of the electrode rod (420) can be positioned to face the upper surface of the molten steel (M). Afterward, power is supplied to the electrode rod (420). As a result, an arc can be generated from the lower end of the electrode rod (420), and the molten steel (M) can be heated.

[0092] In the above, the width of the opening (OP) is greater than or equal to the width of the electrode rod (420), so that the slag solidification layer (SL S An example was described of passing the electrode rod (420) through the opening (OP) without performing the operation to destroy the electrode rod (420). However, before lowering the electrode rod (420), the slag solidification layer (SL S A process to destroy ) can be performed. For example, if the width of the protruding member (320) is smaller than the width of the electrode rod (420), the slag solidification layer (SL S The width of the opening (OP) formed in ) may be smaller than the width of the electrode rod (420). Accordingly, using a separately prepared destruction device, the slag solidification layer (SL S ) can be destroyed. At this time, the slag solidification layer (SL S ) from the region surrounding the opening (OP) to the slag solidification layer (SL S It can destroy ). In addition, the slag solidification layer (SL) is formed to have a width into which the electrode rod can be inserted. S Destroying only a part of the area of ​​) or the slag solidification layer (SL S The entire ) can be destroyed. Accordingly, at least the area of ​​the upper surface of the molten steel facing the electrode rod (420) can be exposed. Next, the electrode rod (420) is lowered so that the lower end of the electrode rod (420) faces the upper surface of the molten steel. In this way, the slag solidification layer (SL S ) from the region surrounding the opening (OP) to the slag solidification layer (SL S By destroying ) the slag solidification layer, it can be destroyed more easily than in the past.

[0093] As another example, using an electrode rod (420), a slag solidification layer (SL S ) can also be destroyed. That is, after placing the electrode rod (420) so as to face the opening (OP), the electrode rod (420) is placed against the slag solidification layer (SL SIt is lowered toward the ) Accordingly, the electrode rod (420) and the slag solidification layer (SL S ) may collide, and due to the impact, the slag solidification layer (SL) around the opening (OP) S ) may be destroyed. Accordingly, the width of the opening (OP) after the collision may increase compared to before the collision. Next, the electrode rod (420) is lowered further so that the lower end of the electrode rod (420) faces the upper surface of the molten steel (M). In this way, the slag solidification layer (SL) in which the opening (OP) has already been formed S By colliding the electrode rod (420) with ), the slag solidification layer (SL S ) can be easily destroyed. And, without using a separate destruction device, the slag solidification layer (SL) can be destroyed using the electrode rod (420). S It can destroy the slag solidification layer (SL). Therefore, compared to conventional methods, the slag solidification layer (SL) S It has the effect of simplifying the task of destroying ).

[0094]

[0095] As such, according to the embodiments of the present invention, the slag solidification layer (SL) before the refining operation S Since the process of destroying ) can be omitted, it has the effect of shortening the refining operation time. In addition, if necessary, the slag solidification layer (SL S Even if a process to destroy ) is carried out, it can be destroyed more easily than in the past. That is, the slag solidification layer (SL) to cover the entire upper surface of the molten steel (M) S ) is not formed, and the slag solidification layer (SL) has an opening (OP) S ) is formed. Accordingly, a slag solidification layer (SL S If fracture is initiated from the periphery of the opening (OP) within ), fracture can be achieved more easily and quickly compared to conventional methods. Therefore, compared to conventional methods, the slag solidification layer (SL S The time required to destroy ) can be shortened, and this has the effect of shortening the refining operation time.

[0096] According to embodiments of the present invention, the operation of breaking the slag solidification layer before the refining operation can be omitted. Furthermore, even if the operation of breaking the slag solidification layer is performed as necessary, it can be broken more easily and quickly compared to conventional methods. Therefore, there is an effect of shortening the refining operation time.

Claims

1. A cover device capable of opening and closing the opening of a ladle capable of holding molten steel, A cover member that can be supported on or separated from the ladle to open and close the opening of the ladle; and A cover device comprising: a protruding member extending downward from the lower surface of the cover member so as to be immersed in a slag layer floating on the upper surface of the molten steel.

2. In Claim 1, The above-mentioned protruding member is a cover device fixed to the lower surface of the above-mentioned cover member.

3. In Claim 1, The above-mentioned protruding member is a cover device comprising a refractory member manufactured from a raw material containing refractory material.

4. In Claim 3, The above-mentioned protruding member is disposed on the inner side of the above-mentioned refractory member and includes a support member manufactured from a material including metal, and The above refractory member is a cover device arranged to surround the outer surface of the above support member.

5. In Claim 1, A cover device in which the lower region of the above-mentioned protruding member has a shape in which the width decreases as it goes downward.

6. In Claim 1, The above-mentioned protruding member is a cover device positioned at the horizontal center of the above-mentioned cover member.

7. In Claim 1, A cover device installed such that the position of the above-mentioned protruding member is the same as the horizontal position of the electrode rod of the heating device that can be placed in the above-mentioned ladle.

8. In any one of claims 1 to 7, A cover device comprising a plurality of the above-mentioned protruding members.

9. In any one of claims 1 to 7, A cover device comprising a guide member extending downward from the edge of the cover member.

10. The process of charging molten steel into the internal space of a ladle; A process of placing a cover member over the opening of the ladle to close the opening, and immersing a protruding member extending downward from the lower surface of the cover member into a slag layer floating on the upper surface of the molten steel; and A method for treating molten steel comprising the process of transferring the ladle to a destination for refining operations.

11. In Claim 10, While the above ladle is being transported, the temperature of the molten steel and slag layer drops, causing the slag layer to solidify, and A method for treating molten steel in which the above slag layer solidifies while the above protruding member is immersed.

12. In Claim 11, A method for treating molten steel in which the above-mentioned protruding member is immersed in a slag layer such that it is positioned at the horizontal center of the ladle.

13. In Claim 11, In immersing the above-mentioned protruding member in the slag layer, A method for treating molten steel by immersing the molten steel contained in the above ladle such that the above protruding member is positioned at the same position as the horizontal position of the electrode rod in a subsequent refining operation.

14. In Claim 13, A process of stopping the transfer of the ladle when the ladle arrives at the aforementioned destination; A process of separating the cover member from the ladle to open the opening of the ladle, separating the protruding member from the solidified slag layer, and forming an opening in which molten steel is exposed in the solidified slag layer; and A method for treating molten steel comprising a process of refining molten steel using the above opening.

15. In Claim 14, The process of refining the molten steel mentioned above is, A process of lowering the electrode rod to pass through the opening so that the upper surface of the exposed molten steel and the lower end of the electrode rod face each other; and A method for treating molten steel comprising the process of heating the molten steel by applying power with the above electrode rod.

16. In Claim 14, The process of refining the molten steel mentioned above is, A process of destroying the slag layer from the region surrounding the opening among the above slag solidification layers; A process of lowering the electrode rod so that the upper surface of the molten steel and the lower end of the electrode rod face each other; and A method for treating molten steel comprising the process of heating molten steel by applying power with the above electrode rod.

17. In Claim 14, The process of refining the molten steel mentioned above is, A process of lowering the electrode rod toward the opening to destroy the slag solidification layer around the opening; A process of further lowering the electrode rod so that the upper surface of the molten steel and the lower end of the electrode rod face each other; and A method for treating molten steel comprising the process of heating molten steel by applying power with the above electrode rod.

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