Molten steel desulfurization method using long nozzle to spray powder

Abstract

The invention provides a molten steel desulfurization method using a long nozzle to inject powder, and belongs to the technical field of metal smelting, and the method comprises the following steps: directly installing a desulfurization powder injection device on the long nozzle, injecting the desulfurization powder into the long nozzle through the injection device, and utilizing the retention time of molten steel in the long nozzle to inject the desulfurization powder into the long nozzle; the molten steel is in full contact with the desulfurization powder before being discharged from the long nozzle, the molten steel is effectively desulfurized through the desulfurization powder before being discharged from the long nozzle, and the sulfur content in the molten steel is reduced; before the long nozzle is opened, the injection device injects the carrier gas, on one hand, the carrier gas can dredge the injection device, the desulfurization powder is prevented from blocking the injection device, and smooth discharge of the desulfurization powder is guaranteed; and on the other hand, the powder outlet uniformity of the desulfurization powder at the beginning of injection and at the end of injection can be improved, so that the uniformity of the whole injection process of the desulfurization powder is ensured, the desulfurization powder is in uniform contact with the molten steel, and the desulfurization effect on the molten steel is improved.

Description

Technical Field

[0001] The present application belongs to the technical field of metal smelting, and in particular relates to a method for desulfurizing molten steel by spraying powder at a long shroud. Background Art

[0002] Non-oriented silicon steel is an electrical steel material with good magnetic properties, which is widely used in motors, transformers and other electrical equipment. Its main advantages include low loss, high magnetic permeability and good corrosion resistance, which is suitable for high-frequency and high-efficiency electromagnetic applications. However, during the smelting process, the molten steel easily reacts with oxygen to form oxides. In addition, impurity elements (such as sulfur, phosphorus, etc.) will affect the performance of the material, so its sulfur content needs to be effectively controlled. The existing process flow for smelting low-sulfur non-oriented silicon steel is cumbersome, with low desulfurization efficiency and high cost. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related art.

[0004] In view of this, according to an embodiment of the present application, a method for desulfurizing molten steel by spraying powder through a long shroud is proposed, comprising:

[0005] Install a blowing device on the long shroud;

[0006] Spraying carrier gas into the long shroud through a spraying device;

[0007] Open the shroud to allow the molten steel to flow out of the shroud;

[0008] Desulfurization powder is sprayed into the long water nozzle through the spraying device.

[0009] In a feasible implementation, molten steel enters the tundish from the ladle through the long shroud, and when the molten steel in the tundish floods the lower shroud of the long shroud, desulfurization powder is pulsedly sprayed into the shroud through a spray device.

[0010] In a feasible implementation manner, when the long shroud includes a bowl mouth and a down pipe, a blowing device is installed on the long shroud, and the steps include:

[0011] Opening an interface on the side wall of the sewer pipe;

[0012] The nozzle of the blowing device is arranged tilted so that the highest point of the nozzle is not higher than the lowest point of the bowl mouth;

[0013] Make the nozzle communicate with the interface, and connect and fix the nozzle with the side wall of the sewer pipe.

[0014] In a feasible implementation manner, when the long shroud includes a bowl mouth and a down pipe, a blowing device is installed on the long shroud, and the steps further include:

[0015] Make the distance between the highest point of the interface and the lowest point of the bowl mouth 300-600mm;

[0016] Make the angle between the axis of the nozzle and the axis of the down pipe 30 to 80 degrees.

[0017] In a feasible implementation manner, when the long shroud includes a bowl mouth and a down pipe, a blowing device is installed on the long shroud, and the steps further include:

[0018] The nozzles are evenly arranged on the downpipe along the circumference of the downpipe;

[0019] The included angle between two adjacent nozzles in the circumferential direction of the sewer pipe is 60°.

[0020] In a feasible implementation, spraying desulfurization powder into the long shroud through a spraying device includes:

[0021] First, the desulfurization powder is sprayed from the first nozzle and the second nozzle for a first period of time, and then the first nozzle and the second nozzle are closed;

[0022] Then, the desulfurization powder is sprayed from the third nozzle and the fourth nozzle for a second period of time, and then the third nozzle and the fourth nozzle are closed;

[0023] Finally, the fifth nozzle and the sixth nozzle spray the desulfurization powder, and after the third time period, the fifth nozzle and the sixth nozzle are closed;

[0024] Among them, the circumferential angle between the first nozzle and the second nozzle is 180°, the circumferential angle between the third nozzle and the fourth nozzle is 180°, and the circumferential angle between the fifth nozzle and the sixth nozzle is 180°; the first time length is equal to the second time length and equal to the third time length.

[0025] In a feasible implementation manner, the mass ratio of desulfurization powder to molten steel is 3 to 13:1000.

[0026] In a feasible implementation, the desulfurization powder is CaF powder, CaO powder or a composite powder of CaF and CaO.

[0027] In a feasible implementation, desulfurization powder is sprayed into the long shroud through a spraying device, and then the following steps are further included:

[0028] After all the molten steel in a ladle enters the tundish, stop spraying the desulfurization powder;

[0029] After continuing to spray the carrier gas for a fourth period of time, the spraying of the carrier gas is stopped.

[0030] In a feasible implementation manner, after continuing to spray the carrier gas for a fourth time period, the spraying of the carrier gas is stopped, and then the steps include:

[0031] Remove the long shroud;

[0032] After the next ladle is delivered, the long shroud is installed between the next ladle and the tundish.

[0033] Compared with the prior art, the method for desulfurizing molten steel by spraying powder at a long shroud in the present application has the following beneficial effects:

[0034] The embodiment of the present application provides a method for desulfurizing molten steel by spraying powder through a long shroud, by directly installing a spraying device for desulfurization powder on the long shroud, spraying desulfurization powder into the long shroud through the spraying device, utilizing the residence time of the molten steel in the long shroud to allow the molten steel to fully contact with the desulfurization powder before being discharged from the long shroud, and effectively desulfurizing the molten steel through the desulfurization powder before the molten steel is discharged from the long shroud, thereby reducing the sulfur content in the molten steel; before opening the long shroud, the spraying device first sprays a carrier gas, on the one hand, the carrier gas can unclog the spraying device, prevent the desulfurization powder from clogging the spraying device, and ensure smooth discharge of the desulfurization powder; on the other hand, it can improve the powder output uniformity of the desulfurization powder at the beginning and end of the spraying, thereby ensuring the uniformity of the entire desulfurization powder spraying process, allowing the desulfurization powder to be in uniform contact with the molten steel, which is beneficial to improving the desulfurization effect on the molten steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0036] Figure 1 A schematic flow chart of steps of a method for desulfurizing molten steel by spraying powder through a long shroud according to an embodiment of the present application;

[0037] Figure 2 A schematic flowchart of the steps of installing a spraying device on a shroud in a method for desulfurizing molten steel by spraying powder at a shroud in accordance with an embodiment of the present application;

[0038] Figure 3 A schematic structural diagram of the installation position of a spraying device of a method for desulfurizing molten steel by spraying powder through a long shroud provided in an embodiment of the present application;

[0039] Figure 4 A schematic flowchart of the steps of installing a spraying device on a shroud in a method for desulfurizing molten steel by spraying powder at a shroud in another embodiment provided by the present application;

[0040] Figure 5 A schematic structural diagram of the installation and arrangement position of the nozzle of a method for desulfurizing molten steel by spraying powder through a long shroud provided in an embodiment of the present application;

[0041] Figure 6 A schematic flow chart of the steps of spraying desulfurization powder into the shroud through a spraying device in a method for desulfurizing molten steel by spraying powder through a shroud in accordance with an embodiment of the present application;

[0042] Figure 7 A schematic flow chart of steps of a method for desulfurizing molten steel by spraying powder through a long shroud in another embodiment provided in the present application;

[0043] Figure 8 A schematic flow chart of steps of a method for desulfurizing molten steel by spraying powder at a long shroud according to another embodiment of the present application;

[0044] in, Figures 1 to 8 The corresponding relationship between the reference numerals and component names in the figure is:

[0045] 11. Long shroud; 12. Interface; 13. Blowing device;

[0046] 111. Bowl mouth; 112. Drain pipe; 130. Spray pipe. DETAILED DESCRIPTION

[0047] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0048] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0049] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0050] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0051] like Figure 1 As shown, according to an embodiment of the present application, a method for desulfurizing molten steel by spraying powder through a long shroud 11 is proposed, and the method for desulfurizing molten steel by spraying powder through a long shroud 11 comprises:

[0052] Step 100: installing a blowing device 13 on the shroud 11. The shroud 11 has a simple structure, low cost, and is easy to replace. By installing the blowing device 13 on the shroud 11, the blowing device 13 is not limited by space, so that the installation position and blowing force of the blowing device 13 can be effectively adjusted according to the flow of molten steel in the shroud 11 and the desulfurization demand;

[0053] Step 200: spraying carrier gas into the long shroud 11 through the spraying device 13 to ensure that the spraying device 13 is unobstructed;

[0054] Step 300: opening the shroud 11 to allow the molten steel to flow out from the shroud 11, and performing rapid desulfurization during the pouring process, which is beneficial to shortening the overall production cycle;

[0055] Step 400: By spraying desulfurization powder into the long water nozzle 11 through the blowing device 13, the desulfurization powder can be delivered to the molten steel more directly, thereby making the desulfurization powder directly contact with the molten steel, thereby reducing the possibility of the desulfurization powder being retained on the slag layer on the surface of the molten steel or escaping. On the basis of ensuring the efficiency and effect of the desulfurization system, the amount of desulfurization powder is reduced, and at the same time, the situation of molten steel being returned to the furnace due to insufficient desulfurization is reduced, thereby improving the continuity of production.

[0056] The embodiment of the present application provides a method for desulfurizing molten steel by spraying powder through a long shroud 11. The method comprises the following steps: directly installing a spraying device 13 for desulfurizing powder on the long shroud 11, spraying desulfurizing powder into the long shroud 11 through the spraying device 13, utilizing the residence time of the molten steel in the long shroud 11 to allow the molten steel to fully contact with the desulfurizing powder before being discharged from the long shroud 11, and effectively desulfurizing the molten steel through the desulfurizing powder before the molten steel is discharged from the long shroud 11, thereby reducing the sulfur content in the molten steel. Before opening the long shroud 11, the spraying device 13 first sprays a carrier gas. On the one hand, the carrier gas can unclog the spraying device 13 to prevent the desulfurizing powder from clogging the spraying device 13, thereby ensuring smooth discharge of the desulfurizing powder. On the other hand, the uniformity of the powder output of the desulfurizing powder at the beginning and end of the spraying can be improved, thereby ensuring the uniformity of the entire desulfurizing powder spraying process, allowing the desulfurizing powder to uniformly contact with the molten steel, which is beneficial to improving the desulfurization effect on the molten steel.

[0057] It can be understood that the shroud 11 is a connector between the ladle and the tundish, and plays a connecting role in the converter tapping and continuous casting. The shroud 11 can effectively control the flow rate of the molten steel and reduce the turbulence of the flow. The shroud 11 extends the flow path, reduces casting defects such as gas inclusions and cold shuts, and improves the integrity and density of the casting.

[0058] Furthermore, the spraying device 13 is connected to the spraying system, and the carrier gas and the desulfurization powder share the same spraying device 13. The medium sprayed by the spraying device 13 is controlled by the spraying system, which helps to accurately control the spraying flow of the carrier gas and the desulfurization powder.

[0059] In some examples, the blowing device 13 may be made of 304 stainless steel to ensure the wear resistance of the blowing device 13 and extend its service life.

[0060] In some examples, the carrier gas for spraying the desulfurization powder may be an inert gas to ensure that the carrier gas does not react with the desulfurization powder.

[0061] Furthermore, when spraying the desulfurization powder, the carrier gas is continuously sprayed to carry the desulfurization powder, and the flow rate of the carrier gas after spraying the desulfurization powder is greater than the flow rate of the carrier gas when carrying the desulfurization powder, so as to ensure that the desulfurization powder enters the long water port 11 better from the spraying device 13 and does not block the spraying device 13. As a preferred solution, when no desulfurization powder enters the long water port 11, the spray flow rate of the carrier gas is 50-120Nm 3 / h, when desulfurization powder enters the long water inlet 11 and chemical reaction occurs, the injection flow rate of carrier gas is 80~150Nm 3 / h, the injection pressure of desulfurization powder is 3 standard atmospheres.

[0062] In a feasible implementation, after the ladle is transferred to the central turntable, the blowing device 13 is installed to start blowing carrier gas and powder desulfurization.

[0063] In this technical solution, the long shroud 11 and the blowing device 13 are installed after the steel plate is delivered to the location, so as to avoid the long shroud 11 and the blowing device 13 occupying too much space and affecting the delivery and installation of the ladle.

[0064] In a feasible implementation, the molten steel enters the tundish from the ladle through the long shroud 11 , and when the molten steel in the tundish floods the lower shroud of the long shroud 11 , the desulfurization powder is pulsedly sprayed into the long shroud 11 through the spraying device 13 .

[0065] In this technical solution, the refined molten steel enters the tundish from the ladle through the long shroud 11 for subsequent continuous casting. Desulfurization powder is sprayed when the molten steel submerges the lower water outlet of the long shroud 11, so that the molten steel can be used to block the lower end of the long shroud 11, thereby preventing the desulfurization powder from directly entering the tundish and avoiding local accumulation of desulfurization powder. It is ensured that the desulfurization powder is in direct contact with the molten steel in the long shroud 11 only, and the uniformity of mixing of the desulfurization powder and the molten steel is ensured. The wastewater and waste gas generated by desulfurization can be directly discharged through the tundish. The pulsating spraying of desulfurization powder can provide sufficient metallurgical power and thermal reaction for the molten steel and the desulfurization powder, more efficiently remove the sulfide inclusions in the molten steel, and quickly and effectively complete the desulfurization task of non-oriented silicon steel. In addition, the pulsating spraying of desulfurization powder can reduce the tendency of the spraying device 13 to be blocked, while saving the amount of desulfurization powder, further reducing production costs.

[0066] like Figure 2 and Figure 3 As shown, in a feasible implementation manner, when the long shroud 11 includes a bowl mouth 111 and a down pipe 112, a blowing device 13 is installed on the long shroud 11, and the steps include:

[0067] Step 110: Opening an interface 12 on the side wall of the sewer pipe 112;

[0068] Step 120: tilt the nozzle 130 of the blowing device 13 so that the highest point of the nozzle 130 is not higher than the lowest point of the bowl mouth 111, so as to prevent the desulfurization powder from floating into the ladle, reduce the waste of the desulfurization powder, and make the desulfurization powder fully contact with the molten steel;

[0069] Step 130: connect the nozzle 130 to the interface 12, and fix the nozzle 130 to the side wall of the sewer pipe 112. The spraying position of the nozzle 130 is fixed, and the spraying amount of the desulfurization powder is adjusted only by adjusting the flow of the carrier gas and the spraying device 13, which is conducive to ensuring the uniformity of the spraying.

[0070] In this technical solution, the blowing device 13 is connected to the downpipe 112 of the long water inlet 11, and the nozzle 130 of the blowing device 13 is not higher than the lowest point of the bowl mouth 111 as a whole. After the desulfurization powder is sprayed, the desulfurization powder is prevented from floating in the long water inlet 11, so that the desulfurization powder and the molten steel react chemically quickly, thereby improving the desulfurization efficiency of the molten steel.

[0071] Furthermore, the nozzle 130 is arranged to be tilted upward so that the inlet end of the nozzle 130 faces upward to prevent the molten steel from flowing back into the nozzle 130, and is also conducive to accurately controlling the injection amount of the desulfurization powder.

[0072] In a feasible implementation manner, when the long shroud 11 includes a bowl mouth 111 and a down pipe 112, a blowing device 13 is installed on the long shroud 11, and the steps further include:

[0073] Step 111: Make the distance between the highest point of the interface 12 and the lowest point of the bowl mouth 111 300-600 mm;

[0074] Step 121: Make the angle between the axis of the nozzle 130 and the axis of the down pipe 112 30-80°.

[0075] In this technical solution, the inclination angle of the nozzle 130 and the installation position of the nozzle 130 on the long water nozzle 11 are further limited. When the nozzle 130 is installed at this position, it is not easy to block the nozzle at the connection between the nozzle 130 and the long water nozzle 11, which can further prevent the desulfurization powder from floating up, thereby more effectively accelerating the chemical reaction between the desulfurization powder and the molten steel.

[0076] As a preferred solution, the diameter of the nozzle 130 is 10 to 18 mm, so that the spraying flow rate of the desulfurization powder is sufficient and it is not easy to be blocked.

[0077] like Figure 4 and Figure 5 As shown, in a feasible implementation manner, when the long shroud 11 includes a bowl mouth 111 and a down pipe 112, a blowing device 13 is installed on the long shroud 11, and the steps further include:

[0078] Step 140: Arrange the nozzles 130 evenly on the downcomer pipe 112 along the circumference of the downcomer pipe 112;

[0079] Step 150: Make the included angle between two adjacent nozzles 130 in the circumferential direction of the downcomer 112 60°.

[0080] In this technical solution, the number of nozzles 130 and the installation positions circumferentially of the long water nozzle 11 are further limited. The blowing device 13 includes a plurality of nozzles 130. The nozzles 130 are evenly arranged on the down pipe 112 along the circumference of the long water nozzle 11, so that the desulfurization powder can be evenly sprayed along the circumference of the down pipe 112, thereby improving the uniformity of the contact between the desulfurization powder and the molten steel.

[0081] It can be understood that there are six nozzles 130 evenly arranged on the outer wall of the sewer pipe 112 along the circumference of the sewer pipe 112. The desulfurization powder is sprayed alternately through multiple nozzles 130 to prevent local accumulation of desulfurization powder and improve the uniformity of desulfurization powder spraying.

[0082] As a preferred solution, a plurality of nozzles 130 spray the desulfurization powder in sequence according to a preset spraying sequence, so as to calculate and control the spraying amount and spraying cycle of the desulfurization powder of a single spray rail.

[0083] like Figure 6 As shown, in a feasible implementation manner, desulfurization powder is sprayed into the long shroud 11 through the spraying device 13, including:

[0084] Step 410: spraying desulfurization powder from the first nozzle and the second nozzle for a first time period, and then closing the first nozzle and the second nozzle;

[0085] Step 420: spraying desulfurization powder from the third nozzle and the fourth nozzle 130 for a second period of time, and then closing the third nozzle and the fourth nozzle 130;

[0086] Step 430: Finally, the fifth nozzle 130 and the sixth nozzle 130 spray the desulfurization powder, and after the third time period, the fifth nozzle 130 and the sixth nozzle 130 are closed;

[0087] Among them, the circumferential angle between the first nozzle and the second nozzle is 180°, the circumferential angle between the third nozzle and the fourth nozzle 130 is 180°, and the circumferential angle between the fifth nozzle 130 and the sixth nozzle 130 is 180°; the first time length is equal to the second time length and equal to the third time length.

[0088] In this technical solution, a plurality of nozzles 130 are grouped in pairs to spray desulfurization powder in a cyclic manner in sequence, with only one group of nozzles 130 working at a time and the spraying duration of each group of nozzles 130 being the same. Two nozzles 130 that are opposite to each other in the circumferential direction of the downcomer 112 are grouped together, so that the desulfurization powder sprayed by the nozzles 130 in the same group undergoes convection impact in the downcomer 112 and forms impact streams, thereby enabling the sprayed desulfurization powder to better react chemically with the molten steel, more efficiently remove sulfide inclusions in the molten steel, and improve the efficiency and effect of powder desulfurization.

[0089] As a preferred solution, the first time length is 30 seconds, that is, the blowing time of one group of nozzles 130 is 30 seconds, and the blowing cycle of three groups of nozzles 130 is 90 seconds.

[0090] In a feasible implementation manner, the mass ratio of desulfurization powder to molten steel is 3 to 13:1000.

[0091] In this technical solution, 3 to 13 kg of desulfurization powder is added to every ton of molten steel to achieve deep desulfurization of the molten steel and control the sulfur content of the non-oriented silicon steel molten steel entering the continuous casting stage to about 0.001%.

[0092] In a feasible implementation, the desulfurization powder is CaF powder, CaO powder or a composite powder of CaF and CaO.

[0093] In this technical solution, CaF powder, CaO powder or a composite powder of CaF and CaO is used as the desulfurization powder. On the one hand, it can reduce the calcium-sulfur ratio, reduce the raw material consumption in the desulfurization process, reduce costs, reduce water evaporation, and improve the desulfurization efficiency. On the other hand, CaF powder, CaO powder or a composite powder of CaF and CaO as a desulfurization powder has surface activity and catalytic oxidation effect, which can promote the direct reaction of SO2, accelerate the dissolution of CaCO3, strengthen the precipitation of CaSO4, promote the rapid oxidation of CaSO3 to CaSO4, prevent the injection device 13 from being blocked, and further improve the desulfurization efficiency.

[0094] As a preferred embodiment, the size of the desulfurization powder is 150 to 350 μm.

[0095] like Figure 7 As shown, in a feasible implementation manner, desulfurization powder is sprayed into the long shroud 11 through the spraying device 13, and then the following steps are further included:

[0096] Step 500: After all the molten steel in a ladle enters the tundish, stop spraying the desulfurization powder;

[0097] Step 600: After continuing to spray the carrier gas for a fourth time period, stop spraying the carrier gas.

[0098] In this technical solution, after the molten steel in a ladle completely enters the middle ladle from the lower water inlet, the spraying of desulfurization powder is stopped, and the remaining desulfurization powder in the nozzle 130 is taken out by continuing to spray the carrier gas to ensure sufficient desulfurization powder and prevent the spraying device 13 from being blocked, so as to ensure that the next desulfurization spraying process is carried out smoothly and continuously.

[0099] In some examples, the fourth time duration is 20 to 30 seconds. After all the molten steel in a ladle is injected into the tundish, the powder spraying system is closed first to stop spraying the desulfurization powder and keep the carrier gas open. After all the molten steel is injected into the tundish, wait for 20 to 30 seconds before stopping spraying the carrier gas to prevent the desulfurization powder from being retained in the nozzle 130, so as to ensure that the desulfurization powder can be sprayed out smoothly next time.

[0100] like Figure 8 As shown, in a feasible implementation manner, after continuing to spray the carrier gas for a fourth time period, the carrier gas is stopped, and then the steps include:

[0101] Step 700: dismantling the shroud 11;

[0102] Step 800: After the ladle of the next furnace is delivered, the long shroud 11 is installed between the ladle and the tundish.

[0103] In this technical solution, before continuous casting, after all the molten steel in a ladle enters the tundish, the long water nozzle 11 needs to be removed. Since the blowing device 13 is connected to the long water nozzle 11, the blowing device 13 can be removed together by removing the long water nozzle 11, and the subsequent continuous casting process can be carried out; after the next ladle is delivered, the long water nozzle 11 is installed between the ladle and the tundish again, and the blowing device 13 can be quickly installed without unnecessary operating steps. It is simple and convenient to use.

[0104] Furthermore, before removing the long shroud 11, it is necessary to check the composition of the molten steel to ensure that the desulfurization task index is met. If the index is not met, desulfurization powder should be added to carry out desulfurization.

[0105] Example:

[0106] After the ladle is transferred to the central turntable, install the 200mm long shroud 11 and the blowing device 13, spray the desulfurization powder and carrier gas, let the gas rush into the long shroud 11, check the leakage of the long shroud 11, and dredge the nozzle 130 to prevent the desulfurization powder from clogging the long shroud 11. Open the slide of the long shroud 11, and inject the molten steel from the ladle through the long shroud 11 into the tundish. When the molten steel in the tundish floods the lower water outlet of the long shroud 11, turn on the powder spraying system to start the pulsating powder spraying of the two opposite nozzles 130, and circulate the nozzles 130 in sequence, and the powder spraying cycle of each group of nozzles 130 is 30s. The ladle has a tonnage of 170t, and the total time for the molten steel to be injected from the ladle into the tundish is 2400s. The pulsating powder spraying cycle of the blowing device 13 is 90s, and 26 groups need to be sprayed continuously.

[0107] After all the molten steel in the ladle is injected into the tundish, first close the powder spraying system to stop spraying powder, keep the carrier gas spraying, and stop spraying the carrier gas after 30 seconds. After all the molten steel is injected into the tundish, test the composition of the molten steel.

[0108] Remove the long water nozzle 11, wait for the next ladle to come over, start the next batch, and end this batch.

[0109] The composition of the molten steel in the tundish was tested using a testing device. The test results showed that the sulfur content in the non-oriented silicon steel was 0.001%, which was 0.0005% less than before powder desulfurization, and the desulfurization rate was 33.3%.

[0110] Comparative Example:

[0111] The sulfur content of the 170t ladle desulfurized by the KR hot metal desulfurization process is 0.0023%. After entering the RHLF furnace, it is refined and various desulfurization powders and scrap steel are added to the molten steel. The sulfur content of the refined steel is 0.0013%. Compared with the desulfurization by spraying powder at the long nozzle 11, the sulfur content is 0.0003% higher.

[0112] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0113] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A method for desulfurizing molten steel by spraying powder through a long shroud, characterized in that: The method for desulfurizing molten steel by spraying powder at a long shroud comprises: Install a blowing device on the long shroud; Spraying carrier gas into the long shroud through the spraying device; Opening the shroud to allow molten steel to flow out of the shroud; Desulfurization powder is sprayed into the long shroud through the spraying device.

2. The method for desulfurizing molten steel by spraying powder through a long shroud according to claim 1, characterized in that: The molten steel enters the tundish from the ladle through the long shroud. When the molten steel in the tundish floods the lower shroud of the long shroud, the desulfurization powder is pulse-sprayed into the long shroud through the spraying device.

3. The method for desulfurizing molten steel by spraying powder through a long shroud according to claim 2, characterized in that: When the long shroud includes a bowl mouth and a down pipe, the steps of installing the blowing device on the long shroud include: Opening an interface on the side wall of the sewer pipe; The nozzle of the blowing device is arranged tilted so that the highest point of the nozzle is not higher than the lowest point of the bowl mouth; The nozzle is connected to the interface, and the nozzle is fixedly connected to the side wall of the sewer pipe.

4. The method for desulfurizing molten steel by spraying powder through a long shroud according to claim 3, characterized in that: When the long shroud includes a bowl mouth and a downpipe, the step of installing a blowing device on the long shroud also includes: The distance between the highest point of the interface and the lowest point of the bowl mouth is 300 to 600 mm; The included angle between the axis of the spray pipe and the axis of the downcomer pipe is 30 to 80 degrees.

5. The method for desulfurizing molten steel by spraying powder through a long shroud according to claim 2, characterized in that: When the long shroud includes a bowl mouth and a downpipe, the step of installing a blowing device on the long shroud also includes: The nozzles are evenly arranged on the downpipe along the circumference of the downpipe; The included angle between two adjacent nozzles in the circumferential direction of the sewer pipe is 60°.

6. The method for desulfurizing molten steel by spraying powder through a long shroud according to claim 5, characterized in that: The method of spraying desulfurization powder into the long shroud through the spraying device comprises: First, the desulfurization powder is sprayed from the first nozzle and the second nozzle for a first period of time, and then the first nozzle and the second nozzle are closed; Then, the desulfurization powder is sprayed from the third nozzle and the fourth nozzle for a second period of time, and then the third nozzle and the fourth nozzle are closed; Finally, the desulfurization powder is sprayed from the fifth nozzle and the sixth nozzle for a third period of time, and then the fifth nozzle and the sixth nozzle are closed; Among them, the circumferential angle between the first nozzle and the second nozzle is 180°, the circumferential angle between the third nozzle and the fourth nozzle is 180°, and the circumferential angle between the fifth nozzle and the sixth nozzle is 180°; the first time length is equal to the second time length and equal to the third time length.

7. The method for desulfurizing molten steel by spraying powder through a long shroud according to claim 2, characterized in that: The mass ratio of desulfurization powder to molten steel is 3-13:1000.

8. A method for desulfurizing molten steel by spraying powder at a long shroud according to any one of claims 1 to 7, characterized in that: The desulfurization powder is CaF powder, CaO powder or a composite powder of CaF and CaO.

9. A method for desulfurizing molten steel by spraying powder at a long shroud according to any one of claims 1 to 7, characterized in that: The method further comprises: spraying desulfurization powder into the long shroud through the spraying device, and then: After all the molten steel in a ladle enters the tundish, stop spraying the desulfurization powder; After continuing to spray the carrier gas for a fourth period of time, the spraying of the carrier gas is stopped.

10. A method for desulfurizing molten steel by spraying powder through a long shroud according to claim 9, characterized in that: After the carrier gas is continuously sprayed for a fourth time period, the carrier gas is stopped from being sprayed, and then the method includes: removing the shroud; After the next furnace ladle is delivered, the long shroud is installed between the next furnace ladle and the tundish.

Images