Manufacturing method of steel

Abstract

A method for operating an electric furnace after pausing the operation thereof, according to the present disclosure, comprises: feeding pig iron, through a supplementary material feed port of the electric furnace, to deposit same underneath an electrode rod of the electric furnace while a roof of the electric furnace is closed; applying a high current to the electrode rod to melt the pig iron to produce a molten material; and introducing scrap into the molten material through a side opening of the electric furnace so as to melt the scrap.

Description

Steel manufacturing method

[0001] The present disclosure relates to a steel manufacturing method capable of reducing the time required for starting an electric furnace after an electric furnace is stopped.

[0002] In general, an electric furnace is a device that melts scrap by an electric arc generated by an applied power source after loading scrap.

[0003] The method of manufacturing steel using an electric furnace preheats scrap with high-temperature exhaust gas generated from the electric furnace to increase energy efficiency, and continuously charges the preheated scrap into the electric furnace to melt it and manufacture molten steel.

[0004] These electric furnaces require regular refractory replacement for long-term operation. When the refractory replacement cycle arrives, the furnace is shut down and the refractory replacement is performed. After the refractory replacement is complete, the furnace is initially loaded with scrap to prepare for operation.

[0005] The initial loading of scrap into the furnace is accomplished using a bucket or magnetic crane with the roof open. This loading process, with the roof open, generates dust, which can cause environmental pollution. Furthermore, the crane-based scrap distribution and leveling process can take excessive time.

[0006] One aspect of the present disclosure is to provide a method for manufacturing steel that can reduce the time required for operation after replacing refractory materials in an electric furnace.

[0007] The technical problems to be achieved in this document are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

[0008] According to an embodiment of the present disclosure, in a method for manufacturing steel after replacing the refractory in an electric furnace comprising a roof and an upper cell and a lower cell, each of which has an electrode hole into which a raw material inlet and an electrode rod are inserted, a method for manufacturing steel may be provided, in which, while the roof is closed, pre-injected iron is injected toward the lower portion of the electrode rod through the raw material inlet, power is applied to the electric furnace to melt the pre-injected iron, and scrap is injected into the electric furnace to melt it, thereby manufacturing molten steel.

[0009] At the same time as the above-mentioned pre-loading is performed, the work of fastening a cooling pipe that supplies cooling water to the electric furnace can be performed.

[0010] The above scrap can be fed through the side opening of the electric furnace while the above loop is closed.

[0011] The above electrode holes may be provided in three locations, and the above raw material input ports may be provided in three locations, each located between the adjacent electrode holes.

[0012] The above-mentioned pre-cast iron can be obtained through a by-product generated through either a steelmaking process or a steelmaking process.

[0013] In another aspect, according to one embodiment of the present disclosure, a method for manufacturing steel may be provided, including an operation termination step of terminating the operation of an electric furnace, a loop opening step of opening a loop of the electric furnace, an upper cell separation step of separating an upper cell of the electric furnace, a low cell replacement step of replacing a low cell of the electric furnace, an upper cell mounting step of mounting an upper cell of the electric furnace, a loop closing step of closing the loop of the electric furnace after the low cell replacement step, a pre-injection step of injecting pre-injection iron toward the lower part of an electrode rod through a raw material inlet provided in the loop while the loop is closed, a pre-injection melting step of melting the pre-injection iron by applying power to the electric furnace, and a molten steel manufacturing step of injecting scrap into the electric furnace and melting it to manufacture molten steel.

[0014] The above loop opening step may include raising the electrode rod of the electric furnace, then discharging the molten steel, and then rotating and opening the loop.

[0015] The above loop opening step may further include performing cooling of the electric furnace.

[0016] The above upper cell separation step may include separating the cooling pipe of the electric furnace and transporting the upper cell to a maintenance position using a crane.

[0017] The above low cell replacement step may include transporting the low cell to a maintenance location using a crane, and transporting and installing a new low cell prepared in advance using the crane.

[0018] The above loop closing step may include performing a fastening operation of a cooling pipe for supplying cooling water in a closed state of the loop.

[0019] The above pre-loading step can be performed simultaneously with the fastening operation of the cooling pipe.

[0020] The above molten steel manufacturing step can continuously supply the scrap through a side opening of the electric furnace.

[0021] The above loop may be provided with three electrode holes into which the electrode rod is inserted, and the above raw material input ports may include three each positioned between the adjacent electrode holes.

[0022] The above-mentioned pre-loading step can prepare the pre-loading iron in a raw material bin, connect the raw material feed chute to the raw material input port, and load the pre-loading iron stored in the raw material bin.

[0023] The above-mentioned pre-cast iron is characterized by being obtained through a by-product generated through either a steelmaking process or a steelmaking process.

[0024] In another aspect, according to one embodiment of the present disclosure, in a steel manufacturing method for manufacturing steel after an electric furnace is shut down, a steel manufacturing method may be provided in which, while the loop of the electric furnace is closed, pre-injected iron is injected into the lower part of an electrode of the electric furnace through a raw material injection port of the electric furnace to be laminated, a large current is applied to the electrode to melt the pre-injected iron and generate a molten substance, and scrap is injected into the molten substance through a side opening of the electric furnace to melt the scrap.

[0025] According to an embodiment of the present disclosure, dust generation can be prevented during the initial loading of scrap into an electric furnace, and the time required for starting the electric furnace can be shortened, thereby improving the productivity of electric furnace operation.

[0026] FIG. 1 is a schematic diagram illustrating a continuous charging type electric furnace according to one embodiment of the present disclosure.

[0027] Figure 2 is a flowchart schematically illustrating a steel manufacturing method according to one embodiment of the present disclosure.

[0028] FIG. 3 is a drawing specifically illustrating a steel manufacturing method according to one embodiment of the present disclosure.

[0029] FIG. 4 is a drawing showing a raw material inlet provided in a loop of an electric furnace according to one embodiment of the present disclosure.

[0030] FIG. 5 is a drawing illustrating a process of pre-loading iron into an electric furnace according to one embodiment of the present disclosure.

[0031] The embodiments described in this specification are only the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents or modified examples that can replace them at the time of filing this application are also included in the scope of the rights of the present invention.

[0032] Additionally, the same reference numbers or symbols presented in each drawing of the present disclosure represent parts or components that perform substantially the same function.

[0033] In addition, the terminology used in this disclosure is used to describe embodiments and is not intended to limit and / or restrict the disclosure. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this disclosure, terms such as “comprise” or “have” are intended to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the disclosure, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0034] Additionally, terms including ordinal numbers such as “first,” “second,” etc. used in the present disclosure may be used to describe various components, but the components are not limited by the terms, and the terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present disclosure, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term “and / or” includes any combination of a plurality of related listed items or any item among a plurality of related listed items.

[0035] Furthermore, the meaning of "identical" in this disclosure includes having similar properties or being similar within a certain range. Furthermore, "identical" means "substantially identical." "Substantially identical" should be understood to include values ​​that fall within the manufacturing error range or values ​​that differ from a reference value within a range that has no significance.

[0036] Additionally, terms such as "~part", "~device", "~block", "~absence", and "~module" may refer to a unit that processes at least one function or operation. For example, the terms may refer to at least one hardware such as an FPGA (field-programmable gate array) / ASIC (application specific integrated circuit), at least one software stored in a memory, or at least one process processed by a processor.

[0037] Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0038] Meanwhile, the terms “front,” “rear,” “left,” and “right” used in the description below are defined based on the drawing, and the shape and position of each component are not limited by these terms.

[0039] Hereinafter, preferred embodiments according to the present disclosure will be described in detail with reference to the attached drawings.

[0040] FIG. 1 schematically illustrates a continuous charging electric furnace according to one embodiment of the present disclosure.

[0041] Referring to Fig. 1, a continuous charging type electric furnace (10) may include a charging section (20), a conveying section (30), a preheating section (40), and a dust collecting section (50).

[0042] The charging section (20) can load scrap (22) onto the upper portion of the conveyor (31) via a crane (21). The scrap (22) loaded onto the charging section (20) can be transported via the conveyor (31) and fed into the electric furnace (10).

[0043] The transport unit (30) can transport the scrap (22) placed in the charging unit (20) to the electric furnace (10). The transport unit (30) can include a conveyor (31) for transporting the scrap (22). The conveyor (31) can extend from the charging unit (20) to the electric furnace (10).

[0044] The preheating unit (40) can preheat the scrap (22) using the exhaust gas (offgas) discharged from the electric furnace (10). The preheating unit (40) can include a water-cooling cover (41) through which the high-temperature gas generated from the electric furnace (10) moves. The water-cooling cover (41) can be installed to cover a portion of the conveyor (31). The upper space of the conveyor (31) surrounded by the water-cooling cover (41) can form a passage through which the high-temperature gas moves. The scrap (22) moving through the conveyor (31) can be preheated within the water-cooling cover (41) and then fed into the electric furnace (10).

[0045] The dust collector (50) can collect dust generated when preheating scrap (22) in the preheating unit (40). The dust collector (50) can collect dust inside the water-cooling cover (41) by sucking in air inside the water-cooling cover (41).

[0046] The electric furnace (10) can receive scrap (22) preheated by the preheating section (40) and melt the input scrap (22) by electric energy to produce molten steel. An opening (11) can be provided on the side of the electric furnace (10). The opening (11) can be connected to a conveyor (31), and the preheated scrap (22) conveyed through the conveyor (31) can be continuously fed through the opening (11).

[0047] That is, in the continuous charging type electric furnace (10), scrap (22) loaded from the charging section (20) to the transfer section (30) is transported by a conveyor (31) and is preheated through heat exchange through the preheating section (40), and the preheated scrap (22) is continuously fed into the electric furnace (10) through the opening (11) and melted to produce molten steel.

[0048] Meanwhile, when using an electric furnace (10) for a long period of time, the refractory material must be replaced regularly. Here, the refractory material includes an upper cell and a lower cell. This refractory material is installed on the inner surface of the furnace, and may be in the form of an upper cell combined with an upper portion of a lower cell.

[0049] Figure 2 is a flowchart schematically illustrating a steel manufacturing method according to one embodiment of the present disclosure. Figure 3 specifically illustrates a steel manufacturing method according to one embodiment of the present disclosure. Figure 4 is a drawing illustrating a raw material inlet provided in a loop of an electric furnace according to one embodiment of the present disclosure. Figure 5 is a drawing illustrating a pre-feeding process of an electric furnace according to one embodiment of the present disclosure.

[0050] Referring to FIGS. 2 and 3, the steel manufacturing method can improve the productivity of electric furnace operation by reducing the work time for securing initial molten steel after replacing electric furnace refractory when the replacement cycle of electric furnace refractory arrives.

[0051] The steel manufacturing method may include an operation termination step (S10), a roof opening step (S20), an upper shell separation step (S30), a lower shell replacement step (S40), an upper shell mounting step (S50), a roof closing step (S60), a granulation iron input step (S70), a granulation iron melting step (S80), and a molten steel manufacturing step (S90).

[0052] The operation termination step (S10) is a process of terminating the operation of the electric furnace (10). To terminate the operation of the electric furnace (10), the power to the electric furnace (10) is turned off (S11).

[0053] The loop opening step (S20) is a process of discharging molten steel from the electric furnace (10) and cooling the electric furnace (10). After the operation of the electric furnace (10) is terminated, the electrode rod (12) is first raised to the top of the loop (13) of the electric furnace (10) (S21). Then, all the molten steel inside the electric furnace (10) is discharged (S22). After the molten steel inside the electric furnace (10) is discharged, the loop (13) is positioned in a standby position by rotating (S23), and the inside of the electric furnace (10) is cooled (S24). The electric furnace (10) can be cooled using a blower.

[0054] The upper cell separation step (S30) is a process of separating the upper cell installed inside the electric furnace (10) from the electric furnace (10) after the cooling of the electric furnace (10) is completed. After the cooling of the electric furnace (10) is completed, the supply of cooling water for cooling the upper cell is cut off (S32), and the cooling pipe installed in the electric furnace (10) through which the cooling water moves is dismantled (S33). After the dismantling of the cooling pipe is completed, the upper cell is transported to a maintenance location using a crane (S34). The upper cell transported to the maintenance location can undergo maintenance work before being re-installed.

[0055] The low cell replacement step (S40) is the process of separating the low cell for refractory replacement and installing a new low cell. After the separation of the upper cell is complete, the low cell is lifted from the electric furnace (10) using a crane and transported to the maintenance location (S41, S42), and the new low cell prepared at the maintenance location is lifted and installed in the electric furnace (10) (S43). At the maintenance location, a new low cell with a pre-assembled refractory can be prepared.

[0056] The upper cell mounting step (S50) is a process of remounting the upper cell, which has been serviced, on top of the low cell after the replacement of the low cell is completed. The upper cell, which has been transported from the maintenance location after being separated from the electric furnace (10), is serviced, and the upper cell, which has completed the service work, is lifted using a crane and then mounted on top of the low cell (S51).

[0057] The loop closing step (S60) is a process of rotating the loop (13) to cover the upper portion of the electric furnace (10) after the upper cell has been installed on the electric furnace (10). In the closed state of the loop (13), the cooling pipe that was dismantled when the upper cell was separated can be reattached, and cooling water can be supplied again to perform a water-flow operation (S61).

[0058] The granulation iron injection step (S70) is a process of introducing granulated iron into the electric furnace (10) while the loop (13) is closed. Granulated iron can be obtained by removing impurities from byproducts generated in the ironmaking process and / or steelmaking process through processes such as drying, crushing, classifying, and screening. Granulated iron can have a particle size of approximately 8 mm.

[0059] The pre-loaded iron obtained through by-products generated from the iron-making process and / or the steelmaking process is stored in advance in the raw material bin (60) (see FIG. 5), and the pre-loaded iron stored in the raw material bin (60) can be fed into the electric furnace (10) through the raw material inlet (14) provided in the loop (13). In addition, the pre-loaded iron stored in the raw material bin (60) can be fed into the electric furnace through the raw material inlet (14) after falling along the raw material feed chute (61) (see FIG. 5) (S71). Here, the feeding of the pre-loaded iron can be performed simultaneously with the fastening of the cooling pipe in a closed state of the loop (13). Therefore, since the initial (first) charging is performed in a closed state of the loop (13) after the electric furnace (10) refractory replacement work, it is possible to prevent dust from flying during the initial charging work. In addition, since the initial charging operation of the electric furnace (10) is performed simultaneously with the fastening of the cooling pipe, the working time can be significantly reduced, and thus productivity can be improved due to the reduction in downtime.

[0060] Referring to Fig. 4, a plurality of raw material input ports (14) may be provided in the loop (13) for inputting pre-injected steel. The raw material input ports (14) may be provided in three locations. For example, if the electric furnace (10) is provided as a three-phase AC electric furnace having three electrode rods, the three raw material input ports (14) may be respectively positioned between adjacent electrode holes (15). The three raw material input ports (14) may be positioned near an imaginary circle connecting the centers of the three electrode holes (15).

[0061] Referring to Fig. 5, the pre-loaded iron (70) falling from the raw material bin (60) through the raw material feed chute (61) can be discharged toward the lower portion of the electrode rod (12). Through this, pre-loaded iron piles (71) can be stacked on the bottom (16) of the electric furnace (10) located below the electrode rod (12). The pre-loaded iron (70) fed from each raw material input port (14) can be discharged toward the direct portion of any one of the three electrode rods (12) and stacked at a predetermined height in the central region of the bottom (16) of the electric furnace (10). The amount of charge fed through each raw material input port (14) can be the same amount of pre-loaded iron (70) based on the initial target charge amount in the furnace. At this time, the amount of charge can be controlled using a load cell provided in the raw material bin (60). This raw material inlet (14) can be used to inject raw materials during the melting operation of the electric furnace (10). In addition, as in the present disclosure, the raw material inlet (14) can be used to inject pre-loaded iron (70) during the initial charging of the electric furnace (10). To this end, the raw material inlet (14) can be provided in a number corresponding to the number of electrode rods (12).

[0062] The pre-melting step (S80) is a process of melting pre-melting iron by applying power to the electric furnace (10). That is, power is applied to the electrode rod (12) of the electric furnace (10) to melt the pre-melting iron pile (71) stacked on the bottom (16) of the electric furnace (10) (S81). High power is applied to the electrode rod (12) from the transformer, and the pre-melting iron pile (71) stacked on the bottom of the electrode rod (12) can be melted due to the arc heat source of the electrode rod (12).

[0063] The molten steel manufacturing step (S90) is a process of manufacturing molten steel by melting scrap (22) by introducing it into the molten iron melted at the bottom of the electric furnace (10). The scrap (22) stacked in the scrap charging section (20) can be melted by being continuously introduced through the opening (11) provided on the side of the electric furnace (10) via a conveyor (31) (S91).

[0064] This steel manufacturing method prevents dust scattering that occurs when replacing refractory materials in an existing electric furnace or loading scrap after a shutdown, which occurs when the loop is open. Furthermore, by using a separate crane to load and level the scrap inside the furnace, the work time required can be significantly reduced. This shortens the preparation time required for starting the furnace after replacing the refractory material, thereby improving the productivity of the furnace.

[0065] While the technical concept of the present invention has been described above through specific examples, the scope of the present invention is not limited to these examples. Various embodiments that can be modified or altered by those skilled in the art without departing from the spirit of the present invention as defined in the claims are also within the scope of the present invention.

Claims

1. A method for manufacturing steel after replacing the refractory material in an electric furnace comprising a loop and an upper cell and a lower cell, wherein the loop and the upper cell are provided with an electrode hole into which a raw material inlet and an electrode rod are inserted. With the above loop closed, the pre-loaded iron is fed toward the lower part of the electrode rod through the above raw material input port, By applying power to the above electric furnace, the above pre-injected iron is melted, A steel manufacturing method for producing molten steel by melting scrap by inserting it into the electric furnace.

2. In paragraph 1, A steel manufacturing method that performs the work of fastening a cooling pipe that supplies cooling water to the electric furnace while simultaneously inserting the above-mentioned pre-loaded steel.

3. In paragraph 1, A steel manufacturing method in which the above scrap is supplied through a side opening of the electric furnace while the above loop is closed.

4. In paragraph 1, The above electrode holes are provided in three locations, A steel manufacturing method in which the above raw material input ports are provided in three locations, each positioned between adjacent electrode holes.

5. In paragraph 1, The above-mentioned pre-cast iron is a steel manufacturing method obtained through a by-product generated through either a steelmaking process or a steelmaking process.

6. Operation termination step to terminate operation with electricity; A loop opening step for opening a loop of the above electric furnace; An upper cell separation step for separating the upper cell of the above electric furnace; A low cell replacement step for replacing the low cell of the above electric furnace; An upper cell mounting step for mounting an upper cell of the above electric furnace; A loop closing step for closing the loop of the electric furnace after the above low cell replacement step; A pre-feeding step of feeding pre-feeding iron toward the lower portion of the electrode rod through a raw material feeding port provided in the loop while the loop is closed; A pre-melting step of melting the pre-melted iron by applying power to the electric furnace; and A steel manufacturing method comprising a molten steel manufacturing step of manufacturing molten steel by inserting scrap into the electric furnace and melting it.

7. In paragraph 6, The above loop opening step is, A steel manufacturing method comprising elevating the electrode rod of the electric furnace, discharging molten steel, and rotating and opening the loop.

8. In paragraph 7, The above loop opening step is, A steel manufacturing method further comprising performing cooling in the electric furnace.

9. In paragraph 8, The above upper cell separation step is, A steel manufacturing method comprising separating the cooling pipe of the electric furnace and transporting the upper cell to a maintenance position using a crane.

10. In paragraph 9, The above low cell replacement step is, A steel manufacturing method comprising transporting the low cell to a maintenance location using a crane and transporting and installing a new low cell prepared in advance using the crane.

11. In paragraph 6, The above loop closing step is, A steel manufacturing method comprising performing a fastening operation of a cooling pipe for supplying cooling water in a closed state of the above loop.

12. In paragraph 11, The above pre-injection step is: A steel manufacturing method performed simultaneously with the fastening operation of the above cooling pipe.

13. In paragraph 6, The above molten steel manufacturing steps are: A steel manufacturing method in which the scrap is continuously supplied through a side opening of the electric furnace.

14. In paragraph 6, The above loop is provided with three electrode holes into which the electrode rods are inserted, A steel manufacturing method comprising three of the above raw material inlets, each positioned between adjacent electrode holes.

15. In paragraph 6, The above pre-injection step is: A steel manufacturing method comprising preparing the above-mentioned pre-loaded steel in a raw material bin, connecting the above-mentioned raw material feed chute to the above-mentioned raw material inlet, and charging the above-mentioned pre-loaded steel stored in the above-mentioned raw material bin.

16. In paragraph 6, A steel manufacturing method characterized in that the above-mentioned pre-cast iron is obtained through a by-product generated through either a steelmaking process or a steelmaking process.

17. In a steel manufacturing method for manufacturing steel after an electric furnace is stopped, With the loop of the above electric furnace closed, the pre-loaded iron is introduced into the lower part of the electrode rod of the above electric furnace through the raw material inlet of the above electric furnace and laminated, By applying a large current to the electrode rod, the pre-injected iron is melted to create a molten material, A steel manufacturing method for melting scrap by introducing scrap into the molten metal through a side opening of the electric furnace.

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