Molten iron pretreatment stirring device and use method thereof

Abstract

The molten iron pretreatment stirring device comprises a stirrer, the stirrer is obliquely inserted into molten iron, the included angle alpha between the stirrer and the horizontal direction is adjustable within the range of 20-60 degrees, the stirrer comprises a stirring rod and stirring rods, the multiple stirring rods are arranged in an axial symmetry mode with the stirring rod as the axis, the stirring rods are parallel to one another, and the stirring rods are parallel to one another. And the stirrer is driven to rotate by taking the stirring rod as an axis. Compared with the prior art, the method has the beneficial effects that 1, the stirring rod directly stirs the desulfurizing agent into the iron liquid, and good dynamic conditions for mixing the iron liquid and the desulfurizing agent are obtained; and 2, as the rotating flow field with the included angle of 20-60 degrees with the vertical direction is obtained, the material exchange rate between the slag and the molten iron is far higher than that of a traditional stirring method.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a molten iron pretreatment stirring device and its usage method, which is suitable for stirring molten iron during molten iron pretreatment. Background Technology

[0002] Hot metal pretreatment desulfurization is an effective way to reduce the desulfurization burden in ironmaking and steelmaking processes, simplify operations, and improve the technical and economic indicators of ironmaking and steelmaking. There are two main types of hot metal desulfurization processes in modern iron and steel metallurgy: the injection method and the KR stirring method. From the perspective of actual production application, both have serious shortcomings. The injection method suffers from low stirring efficiency, leading to insufficient kinetic conditions for hot metal desulfurization. The KR stirring method suffers from severe scouring of the molten iron due to violent rotation, resulting in significant wear of the lining refractory material. Simultaneously, the vortex flow field formed in the molten iron has low entrainment efficiency of the desulfurizing agent. Furthermore, the high blade rotation resistance leads to high blade refractory material wear and high power consumption, both contributing to high desulfurization costs. Therefore, it is necessary to develop a stirring method with high stirring efficiency and high desulfurizing agent entrainment rate.

[0003] "A Desulfurization Gun for Molten Iron" (Application No.: CN202320628530.5, Authorization Announcement No.: CN220537846U) discloses a desulfurization gun for molten iron, relating to the field of molten iron pretreatment technology. It includes a connecting flange, stiffening plates, a refractory protective layer, a blowpipe, and a graphite head. The main body of the gun has a refractory protective layer on its outer side. The front end of the main body is connected to one end of the blowpipe, and a graphite head is installed at the other end of the blowpipe. A positioner is installed at the end of the main body away from the blowpipe. Stiffening plates are installed at the upper end of the main body, and a flange is installed at the top of the stiffening plates. Two layers of reinforcing stiffening plates are uniformly welded to the outer circumference of the blowpipe, and anchors are welded between the two layers. Firstly, a large number of stiffening plates are added inside the gun body to ensure its stability. A replaceable refractory graphite head is added to the gun head to prevent erosion and clogging by splashed slag. Furthermore, as the service life of the gun increases, replacement becomes simpler and more convenient, ensuring that the desulfurization gun can adapt to various changes in molten iron pretreatment conditions.

[0004] The paper "Method for Desulfurizing Molten Iron" (Application No.: CN202311575175.0, Publication No.: CN117660727A) discloses a method for desulfurizing molten iron. The method includes: adding a first amount of limestone to the molten iron when its temperature is higher than a first preset temperature; controlling the rotation of a stirring head while the added limestone melts; adding a second amount of desulfurizing agent to the molten iron when a vortex forms; obtaining stirring parameters and controlling the stirring head to perform stirring and desulfurization based on these parameters. This method allows for the addition of a first amount of limestone to lower the temperature of the molten iron when it is higher than the first preset temperature, thereby reducing the agglomeration of the desulfurizing agent and improving its desulfurization effect. Furthermore, since the decomposition products of limestone can also play a desulfurization role, they can replace part of the desulfurizing agent, further reducing the amount of desulfurizing agent used and achieving cost savings.

[0005] None of the aforementioned patent documents improved the kinetic conditions of mixing molten iron with desulfurizing agents, falling far short of the ideal effect and failing to meet the requirements. Summary of the Invention

[0006] The purpose of this invention is to provide a hot metal pretreatment stirring device and its usage method, which can significantly shorten the kinetic conditions for mixing hot metal and desulfurizing agent, reduce the hot metal desulfurization time, reduce the amount of desulfurizing agent used, thereby making production smoother and reducing production costs.

[0007] To achieve the above objectives, the present invention employs the following technical solution: A stirring device for molten iron pretreatment includes a stirrer, which is inserted into the molten iron at an angle. The angle α between the stirrer and the horizontal direction is adjustable within the range of 20° to 60°. The stirrer includes a stirring rod and a stirring bar. Multiple stirring bars are arranged symmetrically about the stirring rod as an axis and are parallel to each other. The stirrer is driven to rotate about the stirring rod as an axis.

[0008] The number of stirring rods is 2 to 6.

[0009] The outer layer of the agitator is made of refractory material, and the inner core is made of steel material.

[0010] The circumference diameter D of the stirring rod is 500mm to 2500mm; the stirring rod is cylindrical or square, with the diameter of the cylindrical rod ranging from 50 to 250mm, the side length of the square rod ranging from 50 to 250mm, and the length L ranging from 1000mm to 3000mm.

[0011] A method for using a molten iron pretreatment stirring device, specifically including: 1) Move the ladle of molten iron to the processing station; 2) Lower 50% to 80% of the stirring rod length into the molten iron; 3) Add the desulfurizing agent to the surface of the molten iron; 4) Turn on the power. The stirrer will rotate at a speed of 30-180 rpm. 5) After the desulfurization reaches the target value range, stop stirring, raise the agitator, and the process is complete.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. The stirring rod directly stirs the desulfurizing agent into the molten iron, obtaining excellent kinetic conditions for mixing the molten iron and the desulfurizing agent; 2. Because a rotating flow field with an angle of 20° to 60° with the vertical direction is obtained, the mass exchange rate between the slag and the molten iron is much higher than that of traditional stirring methods. 3. Simple structure, and manufacturing cost is far lower than KR mixer; 4. The agitator and lining have low refractory material loss, resulting in low operating costs. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a molten iron pretreatment stirring device and its usage method according to the present invention.

[0014] Figure 2 This is a schematic diagram of the iron pretreatment agitator in this invention.

[0015] In the diagram: 1. Ladle of molten iron; 2. Molten iron; 3. Desulfurizing agent; 4. Agitator; 5. Stirring rod; 6. Stirring bar; 7. Rotation direction of the molten iron flow field. Detailed Implementation

[0016] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0017] To further describe the present invention, the following detailed description is provided in conjunction with embodiments: like Figures 1-2As shown, a molten iron pretreatment stirring device includes a stirrer 4, which is inserted into the molten iron 2 at an angle. The angle α between the stirrer 4 and the horizontal direction is adjustable within the range of 20° to 60°. The stirrer 4 includes a stirring rod 6 and a stirring bar 5. Multiple stirring bars 5 are arranged axially symmetrically about the stirring rod 6 as the axis and are parallel to each other. The stirrer 4 is driven to rotate around the stirring rod 6 as the axis.

[0018] The number of stirring rods 5 is 2 to 6.

[0019] The outer layer of the agitator 4 is made of refractory material, and the inner core is made of steel material.

[0020] The circumference diameter D of the stirring rod 5 is 500mm to 2500mm; the stirring rod 5 is cylindrical or square, with the diameter of the cylindrical rod ranging from 50 to 250mm, the side length of the square rod ranging from 50 to 250mm, and the length L ranging from 1000mm to 3000mm.

[0021] The stirrer 4 includes: a stirring rod 5 and a stirring handle 6, with the following external structure: Figure 2 As shown. The outer layer of the stirring rod 5 and the stirring bar 6 is made of refractory material, and the inner core is made of steel. There are 2 to 6 stirring rods 5, arranged symmetrically about the stirring bar 6, and the stirring rods 5 are parallel to each other. The circumference diameter D of the stirring rod 5 ranges from 500 mm to 2500 mm. The stirring rod 5 is cylindrical or square, with a diameter range of 50 to 250 mm, a side length range of 50 to 250 mm, and a length L range of 1000 mm to 3000 mm. The other end of the stirring bar 6 is connected to the motor, bracket, etc., to form the entire stirrer. The angle α between the axis of the stirring rod 5 and the horizontal direction ranges from 20° to 60°. According to basic physics, the angle β between the rotation direction of the molten iron flow field and the vertical direction is basically the same as α. The rotation speed of the stirrer 4 is 30 to 180 rpm.

[0022] When in use, the relative positions of the stirrer 4 and the molten iron ladle are as follows: Figure 1 As shown, the stirring rod 5 directly stirs the desulfurizing agent into the molten iron, obtaining excellent kinetic conditions for mixing the molten iron and the desulfurizing agent. At the same time, because a rotating flow field with an angle of 20° to 60° with the vertical direction is obtained, the mass exchange rate between the slag and the molten iron is much higher than that of traditional stirring methods.

[0023] A method for using a molten iron pretreatment stirring device, specifically including: 1) The stirrer 4 is prepared according to the structure of the present invention and installed at the pre-desulfurization treatment station of molten iron. The α angle is adjustable within the range of 20° to 60°; 2) Move the molten iron ladle 1 to the processing station; 3) Lower 50% to 80% of the length of the stirring rod 5 into the molten iron; 4) Add the desulfurizing agent to the surface of the molten iron; 5) Turn on the power. The stirrer 4 will rotate at a speed of 30-180 rpm. 6) After the desulfurization reaches the target value range, stop stirring, raise stirrer 4, and the process is complete.

[0024] Example 1: Pre-desulfurization treatment of molten iron in a 150-ton ladle.

[0025] The operation is as follows: 1. A stirrer is prepared according to the structure of this invention. The number of stirring rods 5 is two, each rod-shaped with a diameter of 100 mm and a length of 1500 mm. The circumference diameter D of the stirring rod 5 is 580 mm. The stirrer 4 is installed at the pre-desulfurization treatment station for molten iron. The α angle is adjustable within the range of 20° to 60°; in this treatment, the α angle is 30°. 2. Move the molten iron ladle 1 to the processing station; the sulfur content of the molten iron is 0.040%. 3. Lower 70% of the length of stirring rod 5 into the molten iron; 4. Add 1.5 tons of desulfurizing agent to the surface of the molten iron; 5. Turn on the power. The mixer will start rotating at 50 rpm. 6. After 8 minutes of treatment, the sulfur content drops to 0.0020%. Stop stirring, raise stirrer 4, and the treatment is complete.

[0026] The amount of desulfurizing agent used is 30% lower than that of the KR method, the desulfurization time is 35% shorter than that of the KR method, and the power consumption is 62% lower than that of the KR method. According to statistics, the refractory consumption of the stirring rod 5 is only 32% of that of the KR method, and the refractory consumption of the tank lining is only 66% of that of the KR method.

[0027] Example 2: Pre-desulfurization treatment of molten iron in a 250-ton ladle.

[0028] The operation is as follows: 1. A stirrer 4 is prepared according to the structure of this invention. Two stirring rods 5 are present, each rod-shaped with a diameter of 130 mm and a length of 2000 mm. The circumference diameter D of the stirring rod 5 is 650 mm. The stirrer 4 is installed at the pre-desulfurization treatment station for molten iron. The α angle is adjustable from 20° to 60°; in this treatment, the α angle is 30°. 2. Move the ladle of molten iron to the processing station; the sulfur content of the molten iron is 0.042%. 3. Lower 75% of the length of stirring rod 5 into the molten iron; 4. Add 2.5 tons of desulfurizing agent to the surface of the molten iron; 5. Turn on the power. The mixer 4 will rotate at a speed of 60 rpm. 6. After 8 minutes of treatment, the sulfur content drops to 0.0015%. Stop stirring, raise the stirrer, and the treatment is complete.

[0029] The amount of desulfurizing agent used is 33% lower than that of the KR method, the desulfurization time is 37% shorter than that of the KR method, and the power consumption is 65% lower than that of the KR method. According to statistics, the consumption of refractory material for the stirring rod is only 30% of that of the KR method, and the consumption of refractory material for the tank lining is only 68% of that of the KR method.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A stirring device for molten iron pretreatment, characterized in that, The device includes a stirrer that is inserted at an angle into molten iron. The angle α between the stirrer and the horizontal direction is 20° to 60°. The stirrer includes a stirring rod and stirring bars. Multiple stirring bars are arranged symmetrically about the stirring rod as an axis and are parallel to each other. The stirrer is driven to rotate about the stirring rod as an axis.

2. The iron pretreatment stirring device according to claim 1, characterized in that, The number of stirring rods is 2 to 6.

3. The iron pretreatment stirring device according to claim 1, characterized in that, The outer layer of the agitator is made of refractory material, and the inner core is made of steel.

4. The iron pretreatment stirring device according to claim 1, characterized in that, The circumference diameter D of the stirring rod is 500mm to 2500mm; the stirring rod is cylindrical or square, with the diameter of the cylindrical rod ranging from 50 to 250mm, the side length of the square rod ranging from 50 to 250mm, and the length L ranging from 1000mm to 3000mm.

5. A method of using the molten iron pretreatment stirring device as described in any one of claims 1-4, characterized in that, Specifically, it includes: 1) Move the ladle of molten iron to the processing station; 2) Lower 50% to 80% of the stirring rod length into the molten iron; 3) Add the desulfurizing agent to the surface of the molten iron; 4) Turn on the power. The stirrer will rotate at a speed of 30-180 rpm. 5) After the desulfurization reaches the target value range, stop stirring, raise the agitator, and the process is complete.

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