Protective layer for prolonging service life of blast furnace cooling wall and preparation method

Abstract

The invention provides a protective layer for prolonging the service life of a blast furnace cooling wall and a preparation method, and belongs to the field of blast furnace ironmaking. The protective layer for prolonging the service life of the blast furnace cooling wall comprises a base coat, the surface of the blast furnace cooling wall is covered with the base coat, and coating of the base coat is nickel-based alloy powder; the transition layer covers the surface of the priming layer, and a coating of the transition layer comprises nickel-based alloy powder and blast furnace slag powder; the furnace slag layer covers the surface of the transition layer, and a coating of the furnace slag layer comprises blast furnace slag powder and a reinforcing material. The thermal expansion coefficient of each layer is gradually changed through the multi-layer design, the slag layer is prevented from peeling off, the bonding strength of the slag layer is improved, the protective layer prepared through the method is far thicker than a common coating, the situation that the protective layer is completely abraded is not prone to occurring in the abrasion and corrosion environment, the cooling wall is more effectively protected, and the service life of the cooling wall is prolonged. The service life of the blast furnace cooling wall is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of blast furnace ironmaking, and in particular to a protective layer for improving the life of a blast furnace cooling wall and a preparation method thereof. Background Art

[0002] The cooling wall is a key equipment in blast furnace ironmaking production. It conducts heat from the blast furnace through surface cooling to prevent high-temperature heat flow from impacting the furnace shell. During the smelting process, the cooling wall is in direct contact with the internal charge. It not only has to withstand the mechanical wear of the charge and thermal stress damage caused by temperature changes, but also has to withstand chemical erosion by iron, slag and various gases. These working environments will cause the surface of the cooling wall to be easily worn and eroded. Especially in the furnace waist, belly and lower part of the furnace body, the working conditions are worse, and the cooling wall is more susceptible to serious erosion, which eventually leads to damage. After the cooling wall is damaged, a small amount of water pipes will leak, which will not only increase the frequency of blast furnace overhaul and production maintenance costs, but also cause difficulties in the operation of the blast furnace and affect the smooth production of the blast furnace; once a large amount of cooling water leaks into the furnace, there is a risk of furnace explosion, causing life and economic losses. Therefore, it is particularly important to increase the service life of the cooling wall to ensure the operation of the blast furnace.

[0003] At present, the cooling walls at the furnace waist, furnace belly and the lower part of the furnace body are often extended by embedding refractory bricks and other methods. These measures have a significant effect on extending the life of the cooling walls at the lower part of the furnace body. However, for the cooling walls at the furnace waist and furnace belly, if a certain thickness and stable slag skin is not formed on the surface, under high temperature and wear conditions, the ribs and refractory bricks on the surface of the cooling walls will gradually be worn. After being worn to a certain extent, the refractory bricks will fall off, and eventually the local wear of the cooling walls will be severely caused to break. Therefore, the life of the cooling walls used at the furnace waist and furnace belly is relatively low, and it is urgent to develop a technology for prefabricated slag coating of the cooling walls to effectively increase the life of the cooling walls at this position. Summary of the invention

[0004] The present application provides a protective layer for improving the life of a blast furnace cooling wall and a preparation method thereof, so as to solve the following technical problem: how to improve the life of a blast furnace cooling wall.

[0005] In a first aspect, the present application provides a protective layer for improving the life of a blast furnace cooling wall, the protective layer comprising:

[0006] A primer layer, the primer layer covers the surface of the blast furnace cooling wall, and the coating of the primer layer is nickel-based alloy powder;

[0007] A transition layer, the transition layer covers the surface of the primer layer, the coating of the transition layer comprises: nickel-based alloy powder and blast furnace slag powder; and

[0008] A slag layer, wherein the slag layer covers the surface of the transition layer, and the coating of the slag layer comprises: blast furnace slag powder and reinforcing material.

[0009] Optionally, in the coating of the slag layer, the proportion of the mass of the reinforcing material to the total mass of the coating of the slag layer is greater than 0 and less than or equal to 40%.

[0010] Optionally, the reinforcing material includes: one or more of silicon carbide, silicon nitride and refractory fiber.

[0011] Optionally, the blast furnace slag powder consists of the following chemical components, measured by mass fraction: CaO: 30% to 50%, SiO2: 30% to 50%, Al2O3: 5% to 20%, MgO: 5% to 20%, FeO: 5% to 15%, and MnO: 1% to 2%.

[0012] Optionally, in the coating of the transition layer, the mass ratio of the nickel-based alloy powder to the blast furnace slag powder is 1:(0.5-1.5).

[0013] Optionally, the thickness of the primer layer is 100 μm to 200 μm.

[0014] Optionally, the thickness of the transition layer is 50 μm to 150 μm; and / or,

[0015] The thickness of the slag layer is 10 mm to 70 mm.

[0016] In a second aspect, the present application provides a method for preparing a protective layer according to any one embodiment of the first aspect, the method comprising:

[0017] Roughening the cooling wall of the blast furnace;

[0018] Spraying a primer coating onto the surface of the blast furnace cooling stave after the roughening treatment to form a primer coating on the surface of the blast furnace cooling stave;

[0019] Spraying a coating of a transition layer onto the surface of the primer layer to form a transition layer on the surface of the primer layer;

[0020] Applying a coating of a slag layer to the surface of the transition layer to form a slag layer on the surface of the transition layer;

[0021] The slag layer is roughened to facilitate slagging in the blast furnace and obtain a protective layer.

[0022] Optionally, the method for preparing the coating of the slag layer comprises:

[0023] heating blast furnace slag powder until it is melted to obtain molten slag;

[0024] A reinforcing substance is added to the molten slag to obtain a coating of the slag layer.

[0025] Optionally, during the coating process of the slag layer, cooling water is continuously passed through the cooling wall of the blast furnace.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] The present application provides a protective layer for improving the life of a blast furnace cooling stave, the protective layer comprising: a base layer, the base layer covers the surface of the blast furnace cooling stave, the coating of the base layer is nickel-based alloy powder; a transition layer, the transition layer covers the surface of the base layer, the coating of the transition layer comprises: nickel-based alloy powder and blast furnace slag powder; and a slag layer, the slag layer covers the surface of the transition layer, the coating of the slag layer comprises: blast furnace slag powder and reinforcing material. First, through the multi-layer design of the base layer, the transition layer and the slag layer, the thermal expansion coefficient of each layer gradually changes, effectively preventing the slag layer from peeling off under high temperature and stress. Thereby, the overall bonding strength of the protective layer is improved, so that the protective layer is more firmly attached to the surface of the blast furnace cooling stave. Secondly, the reinforcing material added to the slag layer further improves the wear resistance and erosion resistance of the protective layer. These reinforcing materials can disperse stress and increase toughness, so that the protective layer is less likely to be worn out in a wear and erosion environment. Thirdly, the protective layer is much thicker than ordinary coatings, which provides a longer service life and better protection effect. The increase in thickness enables the protective layer to better resist the scouring and erosion of high-temperature molten metal, thereby increasing the life of the blast furnace cooling wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0030] Figure 1 A schematic diagram of the structure of a protective layer for improving the life of a blast furnace cooling wall provided in an embodiment of the present application;

[0031] Figure 2 A schematic flow chart of a method for preparing a protective layer for increasing the life of a blast furnace cooling wall provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0033] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0034] In addition, in the description of the specification of the present application, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second", etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" means one or more, and "plurality" means two or more. "At least one", "the following at least one item (items)" or similar expressions refer to any combination of these items, including any combination of single items (items) or plural items (items). For example, "at least one of a, b, or c", or "at least one of a, b, and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple. "Parts" such as parts by weight and parts by mass indicate the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one-to-one with the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0035] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0036] Figure 1 A schematic structural diagram of a protective layer for increasing the life of a blast furnace cooling wall provided in an embodiment of the present application.

[0037] like Figure 1 As shown, the present application provides a protective layer for improving the life of a blast furnace cooling wall, the protective layer comprising:

[0038] A primer layer, the primer layer covers the surface of the blast furnace cooling wall, and the coating of the primer layer is nickel-based alloy powder;

[0039] A transition layer, the transition layer covers the surface of the primer layer, the coating of the transition layer comprises: nickel-based alloy powder and blast furnace slag powder; and

[0040] A slag layer, wherein the slag layer covers the surface of the transition layer, and the coating of the slag layer comprises: blast furnace slag powder and reinforcing material.

[0041] Directly preparing a slag layer on the surface of the substrate can easily cause the slag layer to fall off. The bottom layer is designed in the embodiment of the present application to solve the physical incompatibility between the slag layer and the substrate, improve the difference in thermal expansion behavior between the two, relieve thermal stress, and make the copper substrate and non-metallic slag have a higher bond. The nickel-based alloy layer has good oxidation resistance at high temperatures, which can prevent the substrate from being oxidized and causing the slag layer on the substrate surface to fall off. At the same time, the nickel-based alloy layer has good oxidation resistance at high temperatures, which can prevent the substrate from being oxidized and causing the slag layer on the substrate surface to fall off.

[0042] The design of the transition layer aims to further improve the difference in thermal expansion behavior between the slag layer and the substrate. Its thermal expansion coefficient is between the substrate and the slag layer, acting as a bridge, which can effectively relieve thermal stress and improve the thermal shock resistance of the slag layer. At the same time, the addition of blast furnace slag powder also helps to enhance the compatibility and bonding between the transition layer and the slag layer.

[0043] The slag layer is the outermost layer of the blast furnace cooling wall protection layer, directly facing the harsh environment inside the blast furnace. This layer has excellent wear and erosion resistance, and can protect the cooling wall from wear and erosion by blast furnace charge and airflow. The selection of blast furnace slag powder makes the slag layer have similar chemical and physical properties to the slag in the blast furnace, thereby improving the durability and stability of the coating. The addition of reinforcement materials further improves the strength and wear resistance of the slag layer.

[0044] In some embodiments, in the coating of the slag layer, the proportion of the mass of the reinforcing material to the total mass of the coating of the slag layer is greater than 0 and less than or equal to 40%.

[0045] In some embodiments, the reinforcement material includes one or more of silicon carbide, silicon nitride and refractory fiber.

[0046] Reinforcement materials such as silicon carbide (SiC), silicon nitride (Si3N4) and refractory fibers have the characteristics of high hardness, high wear resistance, high corrosion resistance and good high temperature stability. The addition of these materials to the slag layer coating can significantly improve the overall performance of the slag layer, so that it can better adapt to the harsh environment of high temperature, high pressure, strong corrosion and so on in the blast furnace. If the mass of the reinforcement material added is greater than 40%, the uniformity and stability of the slag layer coating will be destroyed, resulting in cracks and falling off of the coating during the preparation and curing process; at the same time, if the mass of the reinforcement material added is greater than 40%, the fluidity and wettability of the slag layer coating will be reduced, making it difficult for the coating to be evenly covered on the substrate surface during spraying or brushing, thereby affecting the overall performance and protective effect of the coating. Exemplarily, the mass of the reinforcement material accounts for 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% and the like in the total mass of the coating of the slag layer.

[0047] In some embodiments, the blast furnace slag powder consists of the following chemical components, measured by mass fraction: CaO: 30% to 50%, SiO2: 30% to 50%, Al2O3: 5% to 20%, MgO: 5% to 20%, FeO: 5% to 15%, and MnO: 1% to 2%.

[0048] The blast furnace slag powder in the slag layer has similar chemical composition to the blast furnace slag actually produced in the furnace, and they will show strong affinity. This affinity helps the slag in the furnace to spontaneously adhere to the surface of the cooling wall after the slag layer is worn and thinned, forming a new protective layer, thereby extending the service life of the cooling wall. These chemical components in the blast furnace slag have high stability and corrosion resistance at high temperatures, and can effectively resist the erosion of molten charge and airflow in the blast furnace. This is crucial to protect the cooling wall from wear and erosion. At the same time, these chemical components can maintain good thermal stability at high temperatures and are not prone to phase change or decomposition, thereby ensuring the stability and reliability of the slag layer in high temperature environments. In addition, due to the affinity between the slag layer and the blast furnace slag in the furnace, when the slag layer has tiny cracks or wear, the blast furnace slag in the furnace can infiltrate and fill these defects, forming a self-healing mechanism, which further enhances the protective effect of the slag layer. Exemplarily, the CaO content can be 30%, 32%, 35%, 40%, 45%, 50%, etc., the SiO2 content can be 30%, 32%, 35%, 40%, 45%, 50%, etc., the Al2O3 content can be 5%, 8%, 10%, 12%, 15%, 20%, etc., the MgO content can be 5%, 8%, 10%, 12%, 15%, 20%, etc., the FeO content can be 5%, 8%, 10%, 12%, 15%, etc., and the MnO content can be 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, etc.

[0049] In some embodiments, in the coating of the transition layer, the mass ratio of the nickel-based alloy powder to the blast furnace slag powder is 1:(0.5-1.5).

[0050] By adjusting the mass ratio of nickel-based alloy powder to blast furnace slag powder to 1:(0.5-1.5), various performance requirements of the coating can be balanced, such as matching of thermal expansion coefficient, oxidation resistance, thermal shock resistance, and bonding between the coating and the substrate. Exemplarily, the mass ratio of nickel-based alloy powder to the blast furnace slag powder can be 1:0.5, 1:0.8, 1:1.0, 1:1.2, 1:1.4, 1:1.5, etc.

[0051] In some embodiments, the primer layer has a thickness of 100 μm to 200 μm.

[0052] The base layer needs to be thick enough to ensure good bonding with the substrate and the slag layer. If the thickness of the base layer is less than 100 μm, it cannot provide sufficient bonding strength and thermal stress relief effect, and is also not conducive to antioxidant protection. If the thickness of the base layer is higher than 200 μm, the internal stress increases, thereby increasing the risk of cracking and falling off of the coating. Exemplarily, the thickness of the base layer can be 100 μm, 120 μm, 140 μm, 160 μm, 180 μm, 200 μm, etc.

[0053] In some embodiments, the transition layer has a thickness of 50 μm to 150 μm.

[0054] The thickness of the transition layer has an important influence on the thermal shock resistance of the slag layer. Only when the thickness of the transition layer is appropriate can it be beneficial to improve the thermal shock resistance of the slag layer. This is because a transition layer that is too thin has limited buffering effect on the difference in thermal expansion coefficient between the slag layer and the substrate, and the slag layer will fail and fall off quickly under thermal shock. As the thickness of the transition layer increases, the buffering effect of the transition layer on the difference in thermal expansion coefficient is continuously improved, so that the thermal shock resistance of the slag layer is also improved. However, an overly thick transition layer will lead to a decrease in the thermal shock resistance of the slag layer. The reason for this phenomenon is that when the transition layer is too thick, more expansion will occur in both the vertical and planar directions. The dual effects of longitudinal force and lateral force on the coating reduce the thermal shock resistance of the slag layer. Exemplarily, the thickness of the transition layer can be 50μm, 60μm, 80μm, 100μm, 120μm, 140μm, 150μm, etc.

[0055] In some embodiments, the slag layer has a thickness of 10 mm to 70 mm.

[0056] The slag layer needs to be thick enough to provide effective protection against the erosion of the molten charge and airflow in the blast furnace. If the slag layer is less than 10 mm thick, its wear and erosion resistance will be greatly reduced, and it will not be able to effectively protect the cooling wall. If the slag layer is thicker than 70 mm, it is also easy to fall off. Exemplarily, the thickness of the slag layer can be 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, etc.

[0057] Figure 2 A schematic flow chart of a method for preparing a protective layer for increasing the life of a blast furnace cooling wall provided in an embodiment of the present application.

[0058] like Figure 2 As shown, the present application provides a method for preparing a protective layer according to any one embodiment of the first aspect, the method comprising:

[0059] S1, roughening the cooling wall of the blast furnace;

[0060] S2, spraying the coating of the primer onto the surface of the blast furnace cooling stave after the roughening treatment to form a primer on the surface of the blast furnace cooling stave;

[0061] S3, spraying the coating of the transition layer onto the surface of the primer layer to form a transition layer on the surface of the primer layer;

[0062] S4, applying the coating of the slag layer to the surface of the transition layer to form a slag layer on the surface of the transition layer;

[0063] S5. The slag layer is roughened to promote slag hanging in the blast furnace to obtain a protective layer.

[0064] In some embodiments, the method for preparing the coating of the slag layer comprises:

[0065] heating blast furnace slag powder until it is melted to obtain molten slag;

[0066] A reinforcing substance is added to the molten slag to obtain a coating of the slag layer.

[0067] In some embodiments, during the coating process of the slag layer, cooling water is continuously passed through the cooling wall of the blast furnace.

[0068] The temperature of liquid slag is very high, reaching over 1000°C. Passing cooling water through the cooling wall of the blast furnace can effectively protect the matrix and accelerate the cooling of the slag to form a slag layer.

[0069] In some embodiments, before step S1, the method further comprises:

[0070] Clean the dust, grease and oxides on the cooling wall surface, wash and dry it.

[0071] In some embodiments, the roughening method in step S1 includes grinding, sandblasting, shot blasting or scratching.

[0072] In some embodiments, the spraying method in steps S2 and S3 includes arc spraying, plasma spraying, flame spraying or explosion spraying.

[0073] In some embodiments, the roughening process in step S5 includes grinding and scratching.

[0074] The preparation method of the protective layer provided in the embodiment of the present application provides excellent protection for the blast furnace cooling wall through a multi-layer design and specific process steps, significantly improving its service life. The following is a detailed description of the advantages of this method:

[0075] 1. Multi-layer design, complementary performance. Base layer: As the base layer of the protective layer, the base layer not only enhances the bonding force between the coating and the substrate, but also effectively relieves thermal stress and prevents the coating from cracking or falling off due to thermal expansion differences through its good thermal expansion coefficient matching and anti-oxidation performance. Transition layer: The design of the transition layer further improves the difference in thermal expansion behavior between the coating and the substrate, and improves the thermal shock resistance of the coating. At the same time, the blast furnace slag powder in its composition also enhances the affinity between the coating and the slag in the furnace, which helps to form a self-healing mechanism. Slag layer: As the outermost layer, the slag layer directly faces the harsh environment in the blast furnace. Its excellent wear and erosion resistance, as well as its affinity with blast furnace slag, enable the coating to maintain a good protective effect in a wear and erosion environment.

[0076] 2. Roughening treatment to enhance bonding strength. During the preparation process, roughening treatment is performed on the blast furnace cooling wall and slag layer to increase the contact area between the coating and the substrate, forming more mechanical interlocking points, thereby enhancing the bonding strength between the coating and the substrate. This helps prevent the coating from falling off due to external forces during use.

[0077] 3. The thermal expansion coefficient changes gradually to prevent peeling. Through the multi-layer design, the thermal expansion coefficient of each layer changes gradually, effectively alleviating the stress caused by the difference in thermal expansion. This design not only improves the overall stability of the coating, but also prevents the slag layer from peeling off due to excessive stress.

[0078] 4. The protective layer is thick and durable. The protective layer prepared by this method is much thicker than ordinary coatings and has stronger durability and wear resistance. In a wear and erosion environment, the protective layer is not easily worn out, thereby more effectively protecting the cooling wall.

[0079] 5. The process is simple and easy to implement. The preparation method is relatively simple and easy to implement. Through the process steps of spraying and coating, a protective layer with a multi-layer structure can be easily prepared. At the same time, the method does not have high requirements on equipment and environment, and is suitable for the protection of blast furnace cooling walls of various sizes.

[0080] In summary, the preparation method of the protective layer has the advantages of multi-layer design, complementary performance, coarsening treatment to enhance bonding strength, gradual change in thermal expansion coefficient to prevent peeling, large protective layer thickness and strong durability, and simple process and easy implementation. These advantages make this method have broad application prospects in the field of blast furnace cooling wall protection.

[0081] The product prepared by the method for preparing the protective layer is the above-mentioned protective layer. The chemical composition and structure of the protective layer prepared by the method for preparing the protective layer can refer to the above-mentioned embodiment. Since the method for preparing the protective layer adopts part or all of the technical solutions of the protective layer embodiment, it at least has all the beneficial effects brought by the technical solutions of the protective layer embodiment, which will not be described one by one here.

[0082] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

[0083] Example 1

[0084] In this embodiment, a base layer, a transition layer and a slag layer are prepared on the surface of the cooling wall. Figure 1 The method comprises the following steps in sequence:

[0085] (1) Clean the dust, grease and oxides on the surface of the cooling wall, and wash and dry it;

[0086] (2) roughening the surface of the cooling wall, and then preparing a primer layer with a thickness of 100 μm on the surface;

[0087] In this step (2), the surface of the cooling wall is roughened by sandblasting; NiAl alloy powder is sprayed onto the surface of the cooling wall by explosion spraying to obtain a NiAl base layer with a thickness of 100 μm;

[0088] (3) preparing a transition layer with a thickness of 150 μm on the surface of the base layer;

[0089] In this step (3), NiAl alloy powder and blast furnace slag powder (CaO 35%, SiO2 35%, Al2O3 12%, MgO 10%, FeO 7%, MnO 1%) are uniformly mixed in a ratio of 1:1, and a transition layer with a thickness of 150 μm is prepared on the surface of the base layer by explosion spraying;

[0090] (4) Take an appropriate amount of blast furnace slag and heat it until it is molten, add reinforcement material to the molten slag, stir it evenly with electromagnetic stirring, apply it to the surface of the transition layer, cool it to room temperature, and roughen the surface to obtain the finished product.

[0091] In this step (4), the reinforcing material is silicon carbide particles, and the addition ratio is 20%; the surface of the slag layer is scratched to form field-shaped grooves, and the thickness of the slag layer is 40 mm.

[0092] Example 2

[0093] In this embodiment, a base layer, a transition layer and a slag layer are prepared on the surface of the cooling wall. Figure 1 The method comprises the following steps in sequence:

[0094] (1) Clean the dust, grease and oxides on the surface of the cooling wall, and wash and dry it;

[0095] (2) roughening the surface of the cooling wall, and then preparing a primer layer with a thickness of 150 μm on the surface;

[0096] In this step (2), the surface of the cooling wall is roughened by grinding; NiCrAl alloy powder is sprayed onto the surface of the cooling wall by plasma spraying to obtain a NiCrAl base layer with a thickness of 150 μm;

[0097] (3) preparing a transition layer with a thickness of 100 μm on the surface of the base layer;

[0098] In this step (3), NiAl alloy powder and blast furnace slag powder (CaO 35%, SiO2 35%, Al2O3 12%, MgO 10%, FeO 7%, MnO 1%) are uniformly mixed in a ratio of 1:1, and a transition layer with a thickness of 100 μm is prepared on the surface of the primer layer by plasma thermal spraying;

[0099] (4) Take an appropriate amount of blast furnace slag and heat it until it is molten, add reinforcement material to the molten slag, stir it evenly with electromagnetic stirring, apply it to the surface of the transition layer, cool it to room temperature, and roughen the surface to obtain the finished product.

[0100] In this step (4), the reinforcing material is silicon carbide particles, and the addition ratio is 25%; the surface of the slag layer is scratched to form field-shaped grooves, and the thickness of the slag layer is 30 mm.

[0101] Example 3

[0102] In this embodiment, a base layer, a transition layer and a slag layer are prepared on the surface of the cooling wall. Figure 1 The method comprises the following steps in sequence:

[0103] (1) Clean the dust, grease and oxides on the surface of the cooling wall, and wash and dry it;

[0104] (2) roughening the surface of the cooling wall, and then preparing a primer layer with a thickness of 200 μm on the surface;

[0105] In this step (2), the surface of the cooling wall is roughened by shot peening; NiCrAlY alloy powder is sprayed onto the surface of the cooling wall by plasma spraying to obtain a NiCrAlY base layer with a thickness of 200 μm;

[0106] (3) preparing a transition layer with a thickness of 50 μm on the surface of the primer layer;

[0107] In this step (3), NiAl alloy powder and blast furnace slag powder (CaO 40%, SiO2 33%, Al2O3 12%, MgO 8%, FeO 6%, MnO 1%) are uniformly mixed in a ratio of 1:1, and a transition layer with a thickness of 50 μm is prepared on the surface of the primer layer by plasma thermal spraying;

[0108] (4) Take an appropriate amount of blast furnace slag and heat it until it is molten, add reinforcement material to the molten slag, stir it evenly by electromagnetic stirring, apply it to the surface of the transition layer, cool it to room temperature, and roughen the surface by sandblasting to obtain the finished product.

[0109] In this step (4), the reinforcing material is silicon nitride particles, and the addition ratio is 30%; the surface of the slag layer is polished to form concave and convex grooves, and the thickness of the slag layer is 50 mm.

[0110] Comparative Example 1

[0111] This comparative example prepares a slag layer on the surface of a cooling wall. It includes the following steps in sequence:

[0112] (1) Clean the dust, grease and oxides on the surface of the cooling wall, and wash and dry it;

[0113] (2) Take an appropriate amount of blast furnace slag (CaO 35%, SiO2 35%, Al2O3 12%, MgO 10%, FeO 7%, MnO1%) and heat it until it is melted. Add reinforcement material to the molten slag, stir it evenly with electromagnetic stirring, apply it to the surface of the cooling wall, cool it to room temperature, and roughen the surface to obtain the finished product.

[0114] The performance of the blast furnace cooling staves with protective layers in Examples 1 to 3 and Comparative Example 1 was tested, and the results are shown in Table 1.

[0115] The test shows that the bonding strength and thermal shock resistance of Examples 1 to 3 are 2 to 5 times better than those of Comparative Example 1, which can more effectively protect the cooling wall and increase its service life.

[0116] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0117] In the embodiment of the present application, the prepared protective layer is much thicker than the ordinary coating, the transition layer improves the bonding strength of the slag layer, the slag layer can effectively protect the cooling wall, and the rough surface promotes continued slag hanging during the production process, thereby improving the service life of the cooling wall.

[0118] In the embodiment of the present application, the protective layer technology is used to protect the cooling wall, so as to increase the service life of the cooling wall.

[0119] In the embodiment of the present application, a multi-layer design is used to gradually change the thermal expansion coefficient of each layer, thereby preventing the slag layer from peeling off and improving the bonding strength of the slag layer. In addition, the protective layer prepared by this method is much thicker than ordinary coatings. In a wear and erosion environment, the protective layer is not easily worn out, thereby more effectively protecting the cooling wall.

[0120] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A protective layer for improving the life of a blast furnace cooling wall, the protective layer comprising: A primer layer, the primer layer covers the surface of the blast furnace cooling wall, and the coating of the primer layer is nickel-based alloy powder; A transition layer, the transition layer covers the surface of the primer layer, the coating of the transition layer comprises: nickel-based alloy powder and blast furnace slag powder; and A slag layer, wherein the slag layer covers the surface of the transition layer, and the coating of the slag layer comprises: blast furnace slag powder and reinforcing material.

2. The protective layer according to claim 1, characterized in that: In the coating of the slag layer, the proportion of the mass of the reinforcing material to the total mass of the coating of the slag layer is greater than 0 and less than or equal to 40%.

3. The protective layer according to claim 2, characterized in that: The reinforcing material includes: one or more of silicon carbide, silicon nitride and refractory fiber.

4. The protective layer according to claim 1, characterized in that: Calculated by mass fraction, the blast furnace slag powder consists of the following chemical components: CaO: 30% to 50%, SiO2: 30% to 50%, Al2O3: 5% to 20%, MgO: 5% to 20%, FeO: 5% to 15%, and MnO: 1% to 2%.

5. The protective layer according to claim 1, characterized in that: In the coating of the transition layer, the mass ratio of the nickel-based alloy powder to the blast furnace slag powder is 1:(0.5-1.5).

6. The protective layer according to claim 1, characterized in that: The thickness of the primer layer is 100 μm to 200 μm.

7. The protective layer according to claim 1, characterized in that: The thickness of the transition layer is 50 μm to 150 μm; and / or, The thickness of the slag layer is 10 mm to 70 mm.

8. A method for preparing the protective layer according to any one of claims 1 to 7, the method comprising: Roughening the cooling wall of the blast furnace; Spraying a primer coating onto the surface of the blast furnace cooling stave after the roughening treatment to form a primer coating on the surface of the blast furnace cooling stave; Spraying a coating of a transition layer onto the surface of the primer layer to form a transition layer on the surface of the primer layer; Applying a coating of a slag layer to the surface of the transition layer to form a slag layer on the surface of the transition layer; The slag layer is roughened to facilitate slagging in the blast furnace and obtain a protective layer.

9. The method according to claim 8, characterized in that The preparation method of the coating of the slag layer comprises: heating blast furnace slag powder until it is melted to obtain molten slag; A reinforcing substance is added to the molten slag to obtain a coating of the slag layer.

10. The method according to claim 8, characterized in that During the coating process of the slag layer, cooling water is continuously passed through the cooling wall of the blast furnace.

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