A deslagging device for improving utilization of KR desulfurizer and a use method thereof

Abstract

The present application relates to the technical fields of steel metallurgy and steelmaking, and discloses a slag discharging device for improving the utilization rate of KR desulfurizer and a use method thereof. The slag discharging device comprises a slag discharging baffle and a lifting device. The cross section of the slag discharging baffle is arc-shaped. The slag discharging baffle is located at one side of a stirring paddle in a molten iron ladle. The connecting line between the arc-shaped openings of the slag discharging baffle coincides with the axial line of the molten iron ladle. The direction of the arc-shaped openings of the slag discharging baffle is consistent with the rotating direction of the stirring paddle. The present application utilizes the swirling force of the molten iron during the stirring process of the KR stirring paddle to block the upper layer of iron slag from flowing into the arc-shaped slag discharging baffle. When the slag discharging baffle is filled with molten iron without slag, the desulfurizer is added to the position of the molten iron without slag, so as to increase the contact area of the desulfurizer and the molten iron and avoid the desulfurizer being wrapped in the iron slag. The device and method greatly improve the time for the desulfurizer to disperse into the molten iron, which plays a great role in improving the utilization of the desulfurizer and the desulfurization efficiency.

Description

Technical Field

[0001] This invention relates to the field of steelmaking technology in the field of iron and steel metallurgy, specifically to a slag discharge device and its usage method for improving the utilization rate of KR desulfurizing agent. Background Technology

[0002] The KR desulfurization method involves inserting a refractory agitator into the molten iron ladle at a certain depth below the molten iron surface and rotating it. As the agitator rotates, a V-shaped vortex (lower at the center and higher around the edges) forms on the molten iron surface. This disperses the added desulfurizing agent particles in the impeller tip area, causing them to be ejected radially, then suspended, rotating around the axis, and floating in the molten iron. This mechanical stirring action draws the desulfurizing agent into the molten iron, where it comes into contact with, mixes, and agitates, thus initiating the desulfurization reaction. After the desulfurization reaction is complete, the resulting dry, viscous slag floats to the surface of the molten iron and mixes with a small amount of blast furnace slag remaining in the ladle. Skimming off this slag achieves the desired desulfurization, and the skimmed-off desulfurized slag becomes the main component of the KR desulfurization slag. The KR stirred pre-desulfurization process, due to its favorable metallurgical reaction thermodynamics and kinetics, can significantly improve desulfurization efficiency and greatly reduce desulfurizing agent consumption under optimal desulfurizing agent ratios and stirring parameters. This process is widely used both domestically and internationally.

[0003] Numerous studies have been conducted on the simulation and optimization of KR desulfurization process parameters, achieving significant desulfurization effects. However, research on the utilization rate of desulfurizing agents in China is limited, and most steel companies currently have low utilization rates. This is mainly because the desulfurizing agent particles are small, and a large portion of these small particles are removed by dust removal devices. Most steel companies recycle and reuse this portion. Furthermore, a large amount of slag flows into the ladle after blast furnace tapping; slag removal is required both before and after KR treatment, and a certain amount of slag remains after removal. Thick (approximately 150-250mm); Iron slag is mainly formed by the reaction of iron ore containing impurities such as silica and aluminum with lime in the blast furnace. Another part of the desulfurizing agent is added to the iron ladle. The iron slag covers the molten iron. After the desulfurizing agent is added, some of the desulfurizing agent is wrapped by the iron slag, forming 2CaO·SiO2 with a high melting point on the outer layer of the desulfurizing agent particles. The inner layer of desulfurizing agent is difficult to react fully with the molten iron. This leads to a reduction in the utilization efficiency of this part of the desulfurizing agent, which is very detrimental to the high efficiency and stability of the desulfurization rate and has a significant impact on the control of the sulfur content after desulfurization.

[0004] Therefore, how to improve the utilization rate of KR desulfurizer and thus change the drawbacks of the existing desulfurizer addition method is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a slag discharge device and method for improving the utilization rate of KR desulfurizing agent, thereby solving the problems of the prior art. This invention utilizes the swirling force of the KR stirring paddle on the molten iron during the stirring process. The paddle is inserted below the iron-slag interface to block the upper layer of iron slag from flowing into the arc-shaped slag discharge device. When slag-free molten iron is formed in the arc-shaped slag discharge device, the desulfurizing agent is added to the slag-free molten iron position, thereby increasing the contact area between the desulfurizing agent and the molten iron and preventing the desulfurizing agent from being encapsulated by the iron slag. This device greatly increases the time for the desulfurizing agent to disperse into the molten iron, which is conducive to the full reaction between the desulfurizing agent and the sulfur element in the molten iron, and plays a significant role in improving the utilization of the desulfurizing agent and the desulfurization efficiency.

[0006] To achieve the above objectives, the technical solution of this invention is a slag discharge device for improving the utilization rate of KR desulfurizer, comprising a slag discharge baffle and a lifting device. The lifting device is connected to the slag discharge baffle and is positioned above the slag discharge baffle, controlling its lifting and lowering. The slag discharge baffle has an arc-shaped cross-section and is a composite material composed of a metal inner plate and refractory material. The slag discharge baffle is located on one side of the stirring paddle inside the molten iron ladle. The line connecting the arc-shaped openings of the slag discharge baffle coincides with the axis of the molten iron ladle, and the direction of the arc-shaped openings of the slag discharge baffle is consistent with the rotation direction of the stirring paddle. Through the above technical solution, the slag discharge device is inserted below the iron-slag interface of the molten iron ladle. The molten iron formed by the stirring of the KR stirring paddle rotates smoothly, causing the molten iron slag layer to flow from the outside of the slag discharge device. After a pure molten iron area is formed within the arc-shaped area of ​​the slag discharge device, the desulfurizer is added to this area, which greatly increases the contact area between the desulfurizer and the molten iron, thereby improving the utilization efficiency of the desulfurizer.

[0007] Furthermore, the distance between the two arc-shaped openings of the slag discharge baffle is 200-300 mm greater than the diameter of the desulfurizing agent discharge port;

[0008] Furthermore, the inner metal plate of the slag discharge baffle is a steel plate with a thickness of 15-30mm, and the thickness of the refractory material is 50-100mm.

[0009] Furthermore, the height of the slag discharge baffle is 700-900mm;

[0010] A method for using a slag discharge device based on the above-mentioned method for improving the utilization rate of KR desulfurizer, the method comprising the following steps:

[0011] S1. After the molten iron ladle enters the station, the slag removal operation is carried out before processing. After the slag removal is completed, the stirring paddle is lowered and inserted to the predetermined stirring depth. The bottom of the slag discharge baffle of the slag discharge device is lowered to 100-200mm below the molten iron surface. At this time, the net air volume of the molten iron ladle before stirring is measured and calibrated as h1.

[0012] S2. Start stirring with the stirring paddle and gradually increase the stirring paddle speed. After the stirring paddle rotates, a vortex is formed. The molten iron level at the edge of the ladle rises and the molten iron level at the center drops. When the stirring paddle speed is increased to 50-70 rpm, measure and calibrate the net air volume h2 of the ladle after stirring.

[0013] S3. Lower the bottom of the slag discharge baffle of the slag discharge device to point H, with a descent amount h = (h1-h2) mm. When the bottom of the slag discharge baffle reaches point H, start adding desulfurizing agent. The area for adding desulfurizing agent is the area within the arc of the slag discharge baffle.

[0014] S4. After the desulfurizing agent is added, raise the slag discharge baffle to the standby position and increase the speed of the agitator to high-speed stirring state, wherein the speed of the high-speed stirring state is 100-130 rpm.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] This invention analyzes the abnormal losses during the addition of desulfurizing agent to the molten iron ladle and discovers the problem of excessive lime coating in the slag after desulfurization. To solve this problem, the invention proposes a method that minimizes contact between the desulfurizing agent and the slag. Utilizing the vortex characteristics created by the KR stirring paddle agitating the molten iron, and the fact that the slag surface moves with the direction of the molten iron, a method of separating the slag and iron in a specific space is employed. A slag-blocking device is placed between the slag and iron interfaces to achieve separation. A relatively pure molten iron is formed within a certain space of the slag-blocking device, and then the desulfurizing agent is added to this area. This increases the contact area between the desulfurizing agent and the molten iron, allowing the desulfurizing agent to quickly enter the molten iron, reducing desulfurizing agent loss, and improving the utilization efficiency of the desulfurizing agent. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0019] Figure 2 This is a schematic diagram showing the net clearance elevation of the molten iron surface in the molten iron ladle according to the present invention.

[0020] Figure 3 This is a schematic diagram illustrating the working principle of the present invention.

[0021] Figure 4 This is a top view of the slag discharge device of the present invention.

[0022] In the diagram: 1. Slag discharge device, 2. Iron ladle, 3. Stirring paddle, 4. Iron liquid level, 5. Desulfurizing agent, 6. Iron slag, 7. Slag discharge baffle. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figure 1-4 As shown, a slag discharge device for improving the utilization rate of KR desulfurizer includes a slag discharge baffle and a lifting device. The lifting device is connected to the slag discharge baffle and is positioned above the slag discharge baffle to control its raising and lowering. The lifting device is a conventional elevator. The slag discharge baffle has an arc-shaped cross-section. The lifting rod of the elevator is connected to the middle part of the top surface of the slag discharge baffle. The slag discharge baffle is a composite material composed of a metal inner plate and refractory material. The slag discharge baffle is located on one side of the stirring paddle inside the molten iron ladle. The line connecting the arc-shaped openings of the baffles coincides with the axis of the molten iron ladle, and the direction of the arc-shaped opening of the slag discharge baffle is consistent with the rotation direction of the stirring paddle. Through the above technical solution, the slag discharge device is inserted below the iron-slag interface of the molten iron ladle. The molten iron formed by stirring with the KR stirring paddle rotates smoothly, causing the molten iron slag layer to flow from the outside of the slag discharge device. After a pure molten iron area is formed in the arc-shaped area of ​​the slag discharge device, the desulfurizing agent is added to this area, which is very beneficial to increasing the contact area between the desulfurizing agent and the molten iron, thereby improving the utilization efficiency of the desulfurizing agent.

[0025] To investigate the relationship between the size of the slag discharge baffle and the utilization efficiency of the desulfurizing agent, a further technical solution is that the distance between the two arc-shaped openings of the slag discharge baffle is 200-300 mm greater than the diameter of the desulfurizing agent discharge port.

[0026] The inner metal plate of the slag discharge baffle is a steel plate with a thickness of 50-100 mm, and the thickness of the refractory material is 50-100 mm.

[0027] The height of the slag discharge baffle is 700-900 mm;

[0028] The distance between the centerline of the slag discharge baffle and the axis of the stirring paddle is;

[0029] A method for using a slag discharge device based on the above-mentioned method for improving the utilization rate of KR desulfurizer, the method comprising the following steps:

[0030] S1. After the molten iron ladle enters the station, the slag removal operation is carried out before processing. After the slag removal is completed, the stirring paddle is lowered and inserted to the predetermined stirring depth. The bottom of the slag discharge baffle of the slag discharge device is lowered to 100-200mm below the molten iron surface. At this time, the net air volume of the molten iron ladle before stirring is measured and calibrated as h1.

[0031] S2. Start stirring with the stirring paddle and gradually increase the stirring paddle speed. After the stirring paddle rotates, a vortex is formed. The molten iron level at the edge of the ladle rises and the molten iron level at the center drops. When the stirring paddle speed is increased to 50-70 rpm, measure and calibrate the net air volume h2 of the ladle after stirring.

[0032] S3. Lower the bottom of the slag discharge baffle of the slag discharge device to point H, with a descent amount h = (h1-h2) mm. When the bottom of the slag discharge baffle reaches point H, start adding desulfurizing agent. The area for adding desulfurizing agent is the area within the arc of the slag discharge baffle.

[0033] S4. After the desulfurizing agent is added, raise the slag discharge baffle to the standby position and increase the speed of the agitator to high-speed stirring state, wherein the speed of the high-speed stirring state is 100-130 rpm.

[0034] Example 1

[0035] This embodiment is based on the above technical solution. Specifically, the production batch is designated as batch 1.

[0036] A factory has a 150-ton nominal iron can, a 600-mm radius agitator, and a 300-mm diameter desulfurizer discharge port.

[0037] The diameter of the arc of the slag discharge baffle is 500mm, the height of the slag discharge baffle is 800mm, and the thickness of the outer refractory material castable is 60mm; and the feeding port is aligned with the arc of the slag discharge device for feeding.

[0038] S1. The molten iron ladle enters the station and the slag removal operation is carried out before processing. After the slag removal is completed, the stirring paddle is lowered to 1300mm, and then the slag blocking device is lowered to 200mm below the slag surface. At this time, the net clearance of the molten iron ladle is measured and calibrated to be h1 = 600mm.

[0039] S2. The stirring paddle starts stirring. The surface of the molten iron slag forms an arc after the stirring paddle rotates. The edge of the ladle rises along the surface of the molten iron, while the molten iron in the center falls. A vortex is formed on the surface of the molten iron. When the stirring speed is increased to 50 rpm, the measured and calibrated clearance at the edge of the ladle is h2 = 400 mm.

[0040] S3. Lower the slag discharge device to point H, with a descent amount of (h1-h2) = 200mm; and start adding desulfurizing agent after the slag discharge device reaches point H.

[0041] S4. After the desulfurizing agent is added, raise the slag discharge device to the standby position, and increase the stirring speed of the agitator to high-speed stirring state, with a speed of 110 rpm.

[0042] Example 2

[0043] This embodiment is based on embodiment 1, but designates this production tank batch as tank batch 2. The difference is as follows:

[0044] The diameter of the arc of the slag discharge baffle is 600mm, the height of the slag discharge baffle is 900mm, and the thickness of the outer refractory material castable is 80mm; and the feeding port is aligned with the arc of the slag discharge device for feeding.

[0045] S1. The molten iron ladle enters the station and slag removal is carried out before processing. After the slag removal is completed, the stirring paddle is lowered to 1300mm. At this time, the net clearance of the molten iron ladle is measured and calibrated to be h1 = 500mm.

[0046] S2. The stirring paddle starts stirring. The surface of the molten iron slag forms an arc after the stirring paddle rotates. The edge of the ladle rises along the molten iron surface, while the molten iron in the center drops. A vortex is formed on the molten iron surface. When the stirring speed is increased to 55 rpm, the measured and calibrated clearance at the edge of the ladle is h2 = 310 mm.

[0047] S3. Lower the slag discharge device to point H, with a descent amount of (h1-h2) = 190mm; and start adding desulfurizing agent after the slag discharge device reaches point H.

[0048] S4. After the desulfurizing agent is added, raise the slag discharge device to the standby position, and increase the stirring speed of the agitator to high-speed stirring state, with a speed of 110 rpm.

[0049] In Examples 3-5, the number of tank batches is 3-5 respectively, and the different parameters involved are shown in Table 1.

[0050] The production process parameters for the five tank batches in the above embodiments are shown in Table 1, and the desulfurization effects are shown in Table 2.

[0051]

[0052] Table 1. Production process parameters for five batches using slag removal devices

[0053]

[0054]

[0055] Table 2. Desulfurization effect of 5 tanks using slag discharge device

[0056] In the table, lime utilization rate = molten iron weight (kg) × desulfurization amount (%) / S 原子质量 ×CaO 原子质量 / (desulfurization dosage * 0.9) * 100.

[0057] Comparative Example

[0058] This comparative example describes a desulfurization process without a slag discharge device, following the steps in Example 1: the nominal tonnage of the iron tank is 150 tons, the radius of the stirring paddle is 600 mm, and the diameter of the desulfurizing agent discharge port is 300 mm.

[0059] The process steps are as follows: molten iron ladle enters the station, and slag removal is performed before treatment. After slag removal, the stirring paddle is lowered to 1300mm and starts stirring. The molten iron slag surface forms an arc after the stirring paddle rotates. The molten iron surface rises along the edge of the ladle and falls in the center, forming a vortex. When the stirring speed is increased to 50rpm, desulfurizing agent is added. After the desulfurizing agent is added, the slag discharge device is raised to the standby position, and the stirring paddle is increased to a high-speed stirring state with a speed of 110rpm.

[0060] Other comparative parameters are shown in Table 3.

[0061] The original desulfurization process was used for six batches of production. The process parameters and desulfurization effect are shown in Table 3.

[0062]

[0063]

[0064] Table 3. Original process parameters and desulfurization effect

[0065] In summary, the slag discharge device of this invention achieves significant desulfurization effect in KR desulfurization treatment. Under the same equipment conditions, the lime utilization rate increases from 4.14% to 9.25%, and the consumption of KR desulfurizing agent is reduced while removing the same amount of sulfur. Therefore, the slag discharge device achieves good results in separating iron slag, and the lime in the desulfurizing agent is fully reacted, avoiding the possibility of iron slag encapsulating the desulfurizing agent and creating better conditions for the desulfurizing agent to quickly enter the interior of the molten iron.

[0066] This invention, starting from the utilization rate of KR desulfurizer, analyzes the influencing factors throughout the entire process from the addition of the desulfurizer to its full reaction. It utilizes the rotational kinetic energy of the slag during the KR stirring process to perform slag removal at the slag interface, forming relatively pure molten iron in the desulfurizer addition area. This increases the contact area between the desulfurizer and the molten iron, removing physical obstacles for the desulfurizer to enter the molten iron and carry out the desulfurization reaction. This invention is simple, practical, and economical; with simple modifications, it can achieve significant economic benefits for the KR desulfurization process.

[0067] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A slag discharge device for improving the utilization rate of KR desulfurizing agent, characterized in that: The device includes a slag discharge baffle and a lifting device. The lifting device is connected to the slag discharge baffle and is positioned above the slag discharge baffle to control its raising and lowering. The slag discharge baffle has an arc-shaped cross-section and is a composite material consisting of a metal inner plate and refractory material. The slag discharge baffle is located on one side of the stirring paddle inside the molten iron ladle. The line connecting the arc-shaped openings of the slag discharge baffle coincides with the axis of the molten iron ladle, and the direction of the arc-shaped openings of the slag discharge baffle is consistent with the rotation direction of the stirring paddle. The distance between the two arc-shaped openings of the slag discharge baffle is 200-300 mm larger than the diameter of the desulfurizing agent discharge port.

2. The slag discharge device for improving the utilization rate of KR desulfurizer according to claim 1, characterized in that: The inner metal plate of the slag discharge baffle is made of steel plate with a thickness of 15-30mm, and the thickness of the refractory material is 50-100mm.

3. The slag discharge device for improving the utilization rate of KR desulfurizer according to claim 2, characterized in that: The height of the slag discharge baffle is 700~900mm.

4. A method of using a slag discharge device for improving the utilization rate of KR desulfurizer as described in claim 1, characterized in that: Includes the following steps: S1. After the molten iron ladle enters the station, the slag removal operation is carried out before processing. After the slag removal is completed, the stirring paddle is lowered and inserted to the predetermined stirring depth. The bottom of the slag discharge baffle of the slag discharge device is lowered to 100~200mm below the molten iron surface. At this time, the net air volume of the molten iron ladle before stirring is measured and calibrated as h1. S2. Start stirring with the stirring paddle and gradually increase the stirring paddle speed. After the stirring paddle rotates, a vortex is formed. The molten iron level at the edge of the ladle rises and the molten iron level at the center drops. When the stirring paddle speed is increased to 50-70 rpm, measure and calibrate the net air volume h2 of the ladle after stirring. S3. Lower the bottom of the slag discharge baffle of the slag discharge device to point H, with a descent amount h = (h1 - h2) mm. When the bottom of the slag discharge baffle reaches point H, start adding desulfurizing agent. The area for adding desulfurizing agent is the area inside the arc of the slag discharge baffle. S4. After the desulfurizing agent is added, raise the slag discharge baffle to the standby position and increase the speed of the agitator to high-speed stirring state, wherein the speed of the high-speed stirring state is 100-130 rpm.

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