Method for repairing large surface of converter by using hot-melt cake pressing slag

Abstract

The invention discloses a method for repairing a large surface of a converter by using hot-melt pressed cake slag, which comprises the following steps of: after the tapping of the converter is finished, purging the slag; the hot-melt pressed cake is added into a converter, and the angle of the converter is adjusted, so that the hot-melt pressed cake reaches the slag repair position; the converter is subjected to deslagging operation after standing; after the slag is poured, no material is added, and residual slag in the converter is splashed so that the slag becomes viscous after being cooled; adjusting the position of the converter to enable the slag to cover the hot-melt pressed cake hanging area; wherein the hot-melt pressed cake is obtained by heating and pressing waste materials generated in the steelmaking process. A good bonding interface can be formed between the hot-melt pressed cake and the converter lining, the chemical property, the thermal expansion coefficient and the like of the hot-melt pressed cake are closer to those of a converter lining material, the hot-melt pressed cake is not prone to falling off, stripping and the like in a high-temperature environment, the stability and durability of a repaired part are effectively improved, and the service life of the converter lining is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel metallurgy, and particularly relates to a method for repairing the large surface of a converter by using hot-melt pressed cakes. BACKGROUND

[0002] As a key equipment in the steelmaking process, the internal lining of the converter will be eroded by various factors during steelmaking. In a high-temperature environment, chemical erosion of molten steel and slag is one of the main causes. The iron oxide and other components in the molten steel will react with the alkaline oxides (such as magnesium oxide and calcium oxide) in the lining, causing the loss of the lining material. The repair operation of the converter refers to the repair operation of the in-service converter for sudden local damage or vulnerable and erodible parts with or without stopping. With the development of the steel industry, higher requirements are put forward for the service life and production efficiency of the converter. In order to reduce production costs and reduce downtime caused by frequent maintenance of the lining, it is very important to optimize the materials required for the repair of the converter and reduce the repair time for stable production.

[0003] Currently, the most commonly used method for repairing the large surface of the converter is the pig iron slag repair method. The principle is to rapidly exchange heat and cool down the pig iron block with the high-temperature liquid slag, so that the high-melting-point substances such as MgO, 2CaO·SiO2 and 3CaO·SiO2 in the slag condense and precipitate, the viscosity of the slag increases, and then the slag is cooled and solidified to adhere to the lining, thereby achieving rapid maintenance of the lining. The weak parts of the lining in the charging side impact area can be locally repaired, the consumption of the repair material can be saved, and the service life of the lining can be prolonged.

[0004] Currently, with the development concept of energy saving and emission reduction, the steelmaking mode is gradually changing from the traditional medium-high molten iron consumption to low molten iron production. Pig iron blocks are gradually becoming scarce resources, and the cost performance of the pig iron blocks used for slag repair is decreasing. Steel enterprises urgently need a slag repair material that can utilize waste materials or by-products in the steelmaking process to achieve effective utilization of resources, reduce slag repair costs, ensure normal operation of the converter, and improve economic and environmental benefits. However, there is no method for repairing the large surface of the converter by using steelmaking waste materials. SUMMARY

[0005] The present application relates to the technical field of steel metallurgy, and particularly relates to a method for repairing the large surface of a converter by using hot-melt pressed cakes.

[0006] In order to achieve the above-mentioned purpose, the present application provides a method for repairing the large surface of a converter by using hot-melt pressed cakes, comprising, After the converter is tapped, the slag is purged; The converter is placed and then the slag is discharged; After the slag is poured out, no material is added, and the remaining slag in the converter is splashed to make the slag viscous after cooling; The position of the converter is adjusted so that the slag covers the hot melt cake pressing area; The hot melt cake is obtained by heating and pressing waste materials generated during the steelmaking process.

[0007] It should be noted that the quality of the slag poured out during the slag pouring operation in the present application does not need to be strictly limited, and the remaining slag in the converter can satisfy the subsequent step of covering the hot melt cake pressing area.

[0008] Further, the hot melt cake composition includes, in mass percentage, TFe≥86%, P≤0.40%, S≤0.10%, As≤0.04%, Ni≤0.3%, Cr≤0.3%, Cu≤0.3%, and the rest is unavoidable impurities. The hot melt cake is made of steel plant waste, which not only realizes resource recycling, but also ensures the basic performance of the charging material.

[0009] Further, the oxygen content of the converter tapping is controlled to be lower than 550ppm, and the molten steel is tapped out. The control of the oxygen content of the tapping can avoid the adverse effects of excessive oxygen on the subsequent slag charging process, and the complete tapping of the molten steel can provide a clean internal environment for the slag charging operation.

[0010] Further, the blowing includes adjusting the oxygen lance to a position with a relative height of 17-18m from the bottom of the converter, and brushing oxygen at a flow rate of 25000-30000Nm³ / h for 10-20s. The specific parameter brushing operation can adjust the state of the slag to make it have good combination conditions with the hot melt cake.

[0011] Further, the adjustment of the angle of the converter includes shaking the converter to 60°-70°, and then shaking the converter to an angle that ensures that the hot melt cake stays in the area that needs to be charged with slag. Strict angle control and safe operation specification can not only ensure that the cake accurately reaches the slag charging position, but also ensure the safety of the operator.

[0012] Further, the addition amount of the hot melt cake is 3-5t for a 150t level converter. The actual use can be adaptively adjusted within this range, and the use amount of the hot melt cake can be appropriately increased or decreased for larger or smaller converters.

[0013] Further, after the hot melt cake reaches the slag charging position, it needs to be stationary for 3-5min. The setting of the stationary time can make the hot melt cake fully adapt to the internal environment.

[0014] Further, the hot melt cake is first loaded into the steel bucket through the suction cup, and then added to the converter through the steel bucket. The suction cup loading method can avoid damage to the hot melt cake.

[0015] Furthermore, the splashing is carried out through an oxygen lance nozzle at 1.5-1.8 MPa.

[0016] Furthermore, the hot-melt pressed cake is cylindrical with a diameter of d and a height of h, wherein 200mm≤d≤300mm and 150mm≤h≤200mm; the looseness of the hot-melt pressed cake when dropped freely from a height of one meter does not exceed 5%. A cake that is too large will prevent the slag from encapsulating it, making it difficult to form an effective protective layer; a cake that is too small will be melted by the high-temperature slag during the furnace loading process, failing to perform its slag-repairing function. The size range of the hot-melt pressed cake is an important guarantee for achieving a good slag-repairing effect.

[0017] This invention also provides the application of the above-mentioned method of using hot-melt pressed slag to repair the large surface of a converter in the iron and steel metallurgy.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. The hot-pressed cake residue of the present invention can form a good bonding interface with the converter lining. Its chemical properties and thermal expansion coefficient are closer to those of the lining material. It is not easy to fall off or peel off in high-temperature environment, which effectively improves the stability and durability of the repaired part and extends the service life of the converter lining.

[0019] 2. The method of the present invention is simple and easy to operate, requiring no complex equipment or technology, and is easy for workers to master and implement, reducing delays and errors caused by complex operation; at the same time, the furnace repair time is greatly shortened to only 8-10 minutes, which greatly reduces the furnace repair cost, reduces converter downtime, and improves production efficiency compared with traditional methods.

[0020] 3. The hot melt pressed cake used in this invention is obtained by heating and pressing the waste generated in the steelmaking process. The energy consumption required is relatively low, and it can effectively reduce repeated repairs caused by weak repairs, further reducing energy waste. In addition, using steel plant waste as raw material reduces waste discharge and new raw material mining, reducing environmental pollution and conforming to the concept of green development. Attached Figure Description

[0021] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A photograph of the hot melt pressed cake prepared in Example 1 is shown; Figure 2 A photograph is shown of the hot melt pressed cake being added to the converter in Example 1; Figure 3 The diagram shows the effect of using hot melt pressed cake residue to repair large surfaces in Example 1. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments and 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.

[0025] Example 1 A method for repairing converter surfaces using hot-melt pressed cake residue includes the following steps: S1. Preparation of hot-melt pressed briquettes. After its own pig iron production was exhausted, the converter steelmaking plant of Liuzhou Iron & Steel Co., Ltd. did not purchase any other pig iron from external sources. Instead, it used waste materials such as dust and iron oxide scale from within the plant area, which were heated and pressed to form hot-melt pressed briquettes. Figure 1 The cylindrical hot-melt cake shown has a controlled diameter of 280mm and a height of 180mm. It is regularly shaped, with flat, non-loose end faces. When dropped freely from a height of one meter, its looseness does not exceed 5%. Testing revealed that the hot-melt cake's composition, by mass percentage, includes 87.3% TFe, 0.17% P, 0.072% S, 0.009% As, 0.014% Ni, 0.046% Cr, and 0.033% Cu, with the remainder being unavoidable impurities. In this step, the hot-melt cake is made from steel plant waste, achieving resource recycling while ensuring the basic performance of the furnace repair material. Strict limitations on size and composition are crucial prerequisites for ensuring the subsequent slag repair effect.

[0026] S2. Select a specific heat for slag replenishment; the converter is a 150t class. Strictly control the oxygen content during tapping to 500ppm to ensure complete slag removal. After tapping, adjust the oxygen lance to a position 17.5m above the furnace bottom and brush oxygen at a flow rate of 27000 Nm³ / h for 15 seconds to complete slag pretreatment. Controlling the tapping oxygen content avoids excessive oxygen adversely affecting the subsequent slag replenishment process. Complete slag removal provides a clean furnace environment for slag replenishment, while the specific oxygen brushing parameters adjust the slag state, ensuring good bonding with the hot-melt pressing cake.

[0027] S3. Beforehand, use suction cups to load 4 tons of hot-melt pressed cakes into the scrap steel hopper, then shake the converter to the slag discharge surface and to 65°. (For example...) Figure 2 As shown, the hot-melt cake is added to the converter via a steel hopper. No personnel are allowed to stand or pass by the platform in front of the converter during the feeding process. After the hot-melt cake enters the furnace, the furnace front fire damper is immediately closed. The converter is then rotated to 90° to ensure the hot-melt cake remains in the area requiring slag repair. The suction cup loading method avoids damage to the hot-melt cake. Strict angle control and safe operating procedures ensure both accurate placement of the cake at the slag repair location and operator safety.

[0028] S4. After the hot-melt pressed cake is placed in the furnace, it is allowed to stand for 4 minutes. Then, some of the slag in the converter is poured out. The remaining slag in the converter after slag pouring is sufficient to cover the area where the hot-melt pressed cake is attached. After pouring the slag, no material is added. Nitrogen gas at a pressure of 1.6 MPa is used through an oxygen lance nozzle to splash the remaining slag in the converter, making the slag viscous after cooling. After splashing the slag, the converter is tilted towards the slag-pouring surface, allowing the fluid slag to cover the area where the hot-melt pressed cake is attached. This strengthens the area where the hot-melt pressed cake is attached, improves its resistance to mechanical impact and chemical corrosion, and ensures the furnace protection effect. The set standing time allows the hot-melt pressed cake to fully adapt to the furnace environment. The slag splashing operation without slag-adjusting materials and the subsequent slag covering can further optimize the bonding effect between the pressed cake and the furnace lining, and improve the durability of the slag patch.

[0029] The effect diagram of using hot-melt pressed cake residue to patch large areas in this embodiment is shown below. Figure 3 As shown.

[0030] Example 2 The difference from Example 1 is that the hot melt pressed cake is a cylinder with a diameter of 250 mm and a height of 150 mm.

[0031] Comparative Example 1 This is the traditional method for repairing converter surfaces, but compared to the example, pig iron is used as the material for repairing converter surfaces.

[0032] Comparative Example 2 The difference from Example 1 is that the hot melt pressed cake is a cylinder with a diameter of 350 mm and a height of 210 mm.

[0033] The results showed that the slag could not wrap the hot melt pressed cake and it was difficult to form an effective protective layer.

[0034] Comparative Example 3 The difference from Example 1 is that the hot melt pressed cake is a cylinder with a diameter of 150 mm and a height of 100 mm.

[0035] The results showed that the hot-melt pressed cake was partially melted by the high-temperature slag and could not play a complete slag-repairing role.

[0036] Comparative Example 4 The difference compared to Example 1 is that purchased self-flowing furnace repair material is used as the furnace repair material.

[0037] Practical application verification showed that both the methods in Examples 1 and 2, when used for furnace repair, could maintain the production of 11 heats of steel, and the converter's lifespan could normally exceed 20,000 heats. Compared with the traditional furnace repair method using pig iron in Comparative Example 1 and the furnace repair method using purchased self-flowing repair material in Comparative Example 4, the overall lifespan of the converter did not decrease. Furthermore, the cost-effectiveness of Examples 1 and 2, which used hot-melt pressed slag for repair, was higher than that of Comparative Example 1, and the effect was good. In addition, the furnace repair time in Examples 1 and 2 was significantly shortened, requiring only 8-10 minutes, while Comparative Example 4 required 45-60 minutes.

[0038] In addition, it should be noted that the hot melt pressing cake in Comparative Example 2 was too large, and the slag could not wrap the hot melt pressing cake, making it difficult to form an effective protective layer, which led to the failure of furnace repair; while the hot melt pressing cake in Comparative Example 3 was too small, and part of the hot melt pressing cake was melted by the high temperature slag, which could not play a complete slag repair role, which also led to the failure of furnace repair.

[0039] In summary, the present invention has the following advantages: 1. Size optimization: The size setting of the hot melt pressing cake has been repeatedly verified. If the pressing cake is too large, the slag will not be able to wrap it and it will be difficult to form an effective protective layer; if the pressing cake is too small, it will be melted by the high temperature slag during the furnace process and will not be able to play a slag repair role. This size range is an important guarantee for achieving a good slag repair effect.

[0040] 2. Performance control: The physical properties of the hot melt pressed cake are crucial. It is necessary to ensure that the looseness of the hot melt pressed cake does not exceed 5% when it is dropped freely from a height of one meter. This is to ensure that it has a good ability to resist slag erosion and that the slag patch can play a long-term role in the steelmaking process.

[0041] 3. Final slag condition control: Suitable slag conditions are the key to successful slag patching of hot melt pressed cakes. By operating such as oxygen brushing, the final slag condition can be precisely controlled, creating favorable conditions for the bonding of hot melt pressed cakes with the furnace lining.

[0042] 4. Bonding effect: After hot melting treatment, the hot melt pressed slag can form a good bonding interface with the converter lining. Its chemical properties and thermal expansion coefficient are closer to those of the lining material. It is not easy to fall off or peel off in high temperature environment, which effectively improves the stability and durability of the repaired part and extends the service life of the converter lining.

[0043] 5. Process and Operation: The method of this invention is simple and easy to operate, requiring no complex equipment or technology, and is easy for workers to master and implement, reducing delays and errors caused by complex operation; at the same time, the furnace repair time is greatly shortened to only 8-10 minutes, which greatly reduces converter downtime and improves production efficiency compared with traditional methods.

[0044] 6. Environmental protection and energy conservation: The energy consumption required in the preparation and use of hot melt pressing is relatively low, and it can effectively reduce repeated repairs caused by weak repairs, further reducing energy waste. In addition, this technology uses steel plant waste as raw material, which reduces waste discharge and new raw material mining, reduces environmental pollution, and is in line with the concept of green development.

[0045] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of using hot melt press cake residue to resurface a converter face, characterized by, The method comprises the following steps: After the converter tapping is finished, the slag is blown; The hot melt briquettes are added into the converter, and the angle of the converter is adjusted so that the hot melt briquettes reach the position of slagging; After the converter is kept still, the slag is poured out; After the slag is poured out, no material is added, and the remaining slag in the converter is splashed so that the slag becomes viscous after being cooled; The position of the converter is adjusted so that the slag covers the hot melt briquettes area; The hot melt briquettes are obtained by heating and pressing the waste materials generated in the steelmaking process.

2. The method of using hot dross to reline the converter face according to claim 1, characterized in that, The hot melt briquettes comprise, in mass percentage, TFe≥86%, P≤0.40%, S≤0.10%, As≤0.04%, Ni≤0.3%, Cr≤0.3%, Cu≤0.3%, and the rest is inevitable impurities.

3. The method of using hot dross to reline the converter face as claimed in claim 1, wherein, The tapping control of the converter is to control the oxygen content in the converter to be lower than 550ppm, and the molten steel is to be tapped out completely.

4. The method of using hot dross to reline the converter face according to claim 1, wherein, The blowing comprises adjusting the oxygen lance to a position with a relative height of 17-18m from the bottom of the converter, and brushing oxygen at a flow rate of 25000-30000Nm³ / h for 10-20s.

5. The method of using hot dross to reline the converter face as claimed in claim 1, wherein, The adjustment of the angle of the converter comprises shaking the converter to 60°-70°, and then shaking the converter to an angle that ensures that the hot melt briquettes stay in the area that needs to be slagged.

6. The method of using hot dross to reline the converter face as claimed in claim 1, wherein, The addition amount of the hot melt briquettes is 3-5t for a 150t level converter.

7. The method of using hot dross to resurface a converter face as defined in claim 1, wherein, After the hot melt briquettes reach the position of slagging, they need to be kept still for 3-5min.

8. The method of using hot dross to reline the converter face according to claim 1, wherein, The hot melt briquettes are first loaded into the steel bucket through the suction cup, and then added into the converter through the steel bucket. The splashing of the slag is performed by the oxygen lance nozzle at 1.5-1.8MPa.

9. The method of using hot dross to resurface a converter face according to any one of claims 1 to 8, wherein, The hot melt briquettes are in the shape of a cylinder with a diameter of d and a height of h, wherein 200mm≤d≤300mm and 150mm≤h≤200mm. The loose degree of the hot melt briquettes is not more than 5% when they are freely falling at a height of one meter.

10. The use of the method for slagging the large surface of the converter with the hot melt briquettes according to any one of claims 1-9 in steel metallurgy.

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