Cooling stave for a vanadium titania blast furnace and method for producing the same

Abstract

The application discloses a cooling wall for a vanadium-titanium blast furnace and a construction method thereof, and belongs to the technical field of design and manufacture of metallurgical production equipment accessories. The application provides the cooling wall for the vanadium-titanium blast furnace and the construction method thereof, which have obviously improved strength and excellent deformation resistance. The cooling wall structure comprises the cooling wall and cooling water pipes embedded in the cooling wall. The cooling wall is composed of copper plates, and at least on the surface of the side of the cooling wall close to the vanadium-titanium blast furnace body, a wear-resistant and heat-insulating metal ceramic composite layer is arranged. The construction method comprises the following steps: firstly, the hot surface of the copper plate is pretreated; then, a transition layer is formed by spraying a NiCr or NiAl bonding layer on the hot surface of the copper plate which has passed the pretreatment; then, a working layer is formed by arranging a Cr3C2-NiCr or WC-Co metal ceramic gradient coating layer on the transition layer; finally, the preparation of the cooling wall is completed by adopting a laser remelting process to eliminate the layered structure and block the pores, or adopting a hot isostatic pressing process to improve the density and the bonding force of the coating layer.

Description

Technical Field

[0001] This invention relates to a cooling wall, and more particularly to a cooling wall for a vanadium-titanium blast furnace, belonging to the field of metallurgical production equipment accessory design and manufacturing technology. This invention also relates to a construction method for manufacturing the aforementioned cooling wall for the vanadium-titanium blast furnace. Background Technology

[0002] The belly, waist, and lower part of the furnace body of vanadium-titanium blast furnaces are high-heat-load areas. Due to the characteristics of the raw materials used in vanadium-titanium blast furnaces, these areas are prone to problems such as Ti(C,N) deposition and unstable slag skin. The insufficient thermal shock resistance and erosion resistance of traditional materials are becoming increasingly apparent. Currently, for vanadium-titanium blast furnaces, copper or ductile iron cooling walls are mainly used from the belly to the lower part of the furnace body, and structurally, they are all cooling walls made of a single material. Although copper cooling walls have good thermal conductivity, they have low strength, are easily deformed, have poor thermal shock resistance, and are expensive. Cast iron cooling walls are more affordable, but they have poor thermal conductivity and pose high safety risks. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a cooling wall for a vanadium-titanium blast furnace with significantly improved strength and excellent deformation resistance. The present invention also provides a construction method for manufacturing the cooling wall for the vanadium-titanium blast furnace.

[0004] The technical solution adopted to solve the above-mentioned technical problems is: a cooling wall structure for a vanadium-titanium blast furnace, including a cooling wall and cooling water pipes embedded in the cooling wall. The cooling wall is made of copper plate, and at least on the surface of the cooling wall facing the vanadium-titanium blast furnace body, a wear-resistant and heat-insulating metal-ceramic composite layer is applied.

[0005] Furthermore, the metal-ceramic composite layer is a chromium carbide-based metal-ceramic composite layer, with nickel or cobalt used as the metal binder between the chromium carbide-based metal and the ceramic.

[0006] The preferred method of the above scheme is that after the chromium carbide-based metal ceramic composite layer is laid, the arrangement structure is formed from the inside to the outside in the order of copper → copper + nickel → nickel → nickel + ceramic → ceramic.

[0007] Furthermore, the metal-ceramic composite layer is a tungsten carbide-based metal-ceramic composite layer, with nickel or cobalt used as the metal binder between the tungsten carbide-based metal and the ceramic.

[0008] The preferred method of the above scheme is that after the tungsten carbide-based metal-ceramic composite layer is laid, the arrangement structure is formed from the inside to the outside in the order of copper → copper + nickel → nickel → nickel + ceramic → ceramic.

[0009] Furthermore, yttrium oxide, which stabilizes zirconium oxide, is added to chromium carbide-based or tungsten carbide-based metal materials.

[0010] The preferred embodiment of the above scheme is that fiber optic sensors for monitoring wall temperature and stress are also integrated into the metal-ceramic composite layer; and a remaining life monitor is also installed in the metal-ceramic composite layer.

[0011] The construction method for manufacturing the cooling wall for the vanadium-titanium blast furnace includes a cooling wall embedded with cooling water pipes. The construction method first cleans and roughens the hot surface of the copper plate, then sprays a NiCr or NiAl bonding layer onto the qualified hot surface of the copper plate to form a transition layer, then applies a Cr3C2-NiCr or WC-Co cermet gradient coating on the NiCr or NiAl bonding layer to form a working layer, and finally uses a laser remelting process to eliminate the layered structure and seal the pores, or performs hot isostatic pressing to improve the density and adhesion of the coating to complete the preparation of the cooling wall.

[0012] Furthermore, while spraying the NiCr or NiAl bonding layer, the fiber optic sensor is at least laid into the NiCr or NiAl bonding layer. The thickness of the NiCr or NiAl bonding layer is between 50 and 100 micrometers, and the thickness of the Cr3C2-NiCr or WC-Co cermet gradient coating is between 0.3 and 0.8 mm.

[0013] The preferred method of the above scheme is that the roughening treatment is completed by sandblasting, the NiCr or NiAl bonding layer is completed by high-speed oxygen fuel spraying or atmospheric plasma spraying, and the Cr3C2-NiCr or WC-Co metal ceramic gradient coating is completed by high-speed oxygen fuel spraying.

[0014] The beneficial effects of this invention are as follows: The technical solution provided in this application is based on a cooling wall embedded with cooling water pipes. By improving the cooling wall to a copper plate, and then applying a wear-resistant and heat-insulating metal-ceramic composite layer to at least the surface of the cooling wall on the side adjacent to the vanadium-titanium blast furnace body, a new cooling wall structure is formed. Thus, due to the metal-ceramic composite layer applied to the surface of the improved cooling wall, the strength of the cooling wall can be effectively improved, and its deformation resistance can be enhanced as much as possible. This achieves the goal of minimizing safety risks during use while ensuring the thermal conductivity of the cooling wall. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the cooling wall structure used in the vanadium-titanium blast furnace according to the present invention.

[0016] The diagram is labeled as follows: Cooling wall 1, Cooling water pipe 2, Metal-ceramic composite layer 3. Detailed Implementation

[0017] like Figure 1This invention illustrates a cooling wall for a vanadium-titanium blast furnace with significantly improved strength and excellent deformation resistance, as well as a construction method for manufacturing the cooling wall. The cooling wall structure includes a cooling wall 1 and cooling water pipes 2 embedded in the cooling wall 1. The cooling wall 1 is made of copper plate, and a wear-resistant and heat-insulating metal-ceramic composite layer 3 is applied to at least the surface of the cooling wall 1 facing the vanadium-titanium blast furnace body. The technical solution provided in this application is based on a cooling wall with embedded cooling water pipes. By improving the cooling wall to a copper plate and then applying a wear-resistant and heat-insulating metal-ceramic composite layer to at least the surface of the cooling wall facing the vanadium-titanium blast furnace body, a new cooling wall structure is formed. Thus, due to the metal-ceramic composite layer applied to the surface of the improved cooling wall, the strength of the cooling wall can be effectively improved, and its deformation resistance can be enhanced as much as possible, thereby minimizing the safety risks during use while ensuring the thermal conductivity of the cooling wall.

[0018] Accordingly, to maximize the strength and deformation resistance of the copper plate cooling wall, the metal-ceramic composite layer 3 of this application can be either a chromium carbide-based metal-ceramic composite layer or a tungsten carbide-based metal-ceramic composite layer. Regardless of whether a chromium carbide-based or tungsten carbide-based metal-ceramic composite layer is used, nickel or cobalt is used as the metal bonding phase between it and the ceramic, resulting in an arrangement structure of copper → copper + nickel → nickel → nickel + ceramic → ceramic. Furthermore, this application adds yttrium oxide, a component that stabilizes zirconium oxide, to the chromium carbide-based or tungsten carbide-based metal material. In this case, to monitor the temperature and stress of the copper plate cooling wall during operation, this application also integrates fiber optic sensors for monitoring wall surface temperature and stress in the metal-ceramic composite layer 3; and to monitor the service life of the copper plate cooling wall, this application also includes a remaining life monitor in the metal-ceramic composite layer 3.

[0019] Thus, the cooling wall based on the embedded cooling water pipes can be manufactured as follows: First, the hot surface of the copper plate is cleaned and roughened. Then, a NiCr or NiAl bonding layer is sprayed onto the qualified hot surface of the copper plate to form a transition layer. Next, a Cr3C2-NiCr or WC-Co cermet gradient coating is applied on the NiCr or NiAl bonding layer to form a working layer. Finally, a laser remelting process is used to eliminate the layered structure and seal the pores, or a hot isostatic pressing process is performed to improve the density and adhesion of the coating to complete the preparation of the cooling wall. At this time, in order to facilitate the placement of the integrated fiber optic sensor, the fiber optic sensor is at least placed in the NiCr or NiAl bonding layer while spraying the NiCr or NiAl bonding layer. Accordingly, in order to improve wear resistance and corrosion resistance, the thickness of the NiCr or NiAl bonding layer applied in this application is between 50-100 micrometers, and the thickness of the Cr3C2-NiCr or WC-Co cermet gradient coating applied in this application is between 0.3-0.8 mm. Based on the existing technology, the roughening treatment in this application is completed by sandblasting, the NiCr or NiAl bonding layer is completed by high-speed oxygen fuel spraying or atmospheric plasma spraying, and the Cr3C2-NiCr or WC-Co metal ceramic gradient coating is completed by high-speed oxygen fuel spraying.

[0020] The technical solution of this application will be further described below through specific embodiments: 1. Develop functional coating systems Coating materials: Develop new composite coatings (such as metal ceramics) to actively improve slag adhesion while providing heat insulation and protecting the substrate, making the slag more stable and reducing the impact of detachment on the copper wall.

[0021] Coating structure: Design gradient coating or multi-layer structure to ensure a smooth transition in properties such as thermal conductivity and thermal expansion coefficient in the direction from the hot surface to the copper substrate, reduce interfacial stress, and prevent the coating from peeling off under thermal shock.

[0022] 2. Optimize the bonding interface between the copper substrate and the coating. This is the key factor in determining whether the coating can serve a long-term purpose.

[0023] Interface strengthening technology: By pre-treating the hot surface of the copper plate, such as through laser cladding or special sintering, a metallurgical or strong mechanical bonding transition layer is constructed, which greatly improves the bonding strength between the coating and the copper plate.

[0024] Collaborative anti-deformation design: Combining the anti-deformation design of the "interactive copper cooling wall" with side boss structure or elliptical positioning pin holes, the deformation of the copper plate is reduced from the structure, providing more stable support for the brittle coating.

[0025] 3. Design intelligent or adaptive cooling walls By combining coatings with monitoring and control technologies, a higher level of innovation can be achieved: 1) Coatings as sensing or response units: Explore whether coatings can be integrated with fiber optic sensors for online monitoring of wall temperature and stress. Or research smart material coatings whose thermophysical properties can adapt to temperature changes.

[0026] 2) Combining life prediction models: By combining the cooling wall with the existing "remaining life monitoring model", the new cooling wall is not just a piece of hardware, but a predictable and maintainable long-life solution.

[0027] 4. Core Performance Analysis and Material Selection 1) Abrasion resistance and high-temperature strength a. Preferred materials: metal-ceramic composites, especially chromium carbide (Cr3C2)-based or tungsten carbide (WC)-based materials, with nickel (Ni) or cobalt (Co) as the metal binder phase.

[0028] b. Performance Analysis: The ceramic hard phase provides extremely high hardness and wear resistance; the metallic binder phase provides toughness and strength at high temperatures, preventing the coating from becoming brittle. These coatings are typically prepared using high-velocity flame spraying (HVOF), resulting in extremely dense coatings with high bonding strength.

[0029] 2) High temperature resistance and thermochemical stability a. Challenges: Resisting high temperatures (>1200℃) inside the blast furnace, CO corrosion, alkali metal vapor and slag corrosion.

[0030] b. Solution: Add yttrium oxide (Y₂O₃) and stabilizing zirconia (ZrO₂) to the coating. Zirconia itself is an excellent thermal barrier coating material; adding stabilizers can prevent high-temperature phase transformations, significantly improving thermal shock resistance and insulation. Aluminide coatings can also be considered, forming a dense Al₂O₃ protective film at high temperatures.

[0031] 3) Thermal shock stability (resistance to thermal fatigue) a. Core contradiction: The mismatch between the coefficient of thermal expansion (CTE) of the coating and the copper substrate is the root cause of the coating cracking and peeling during thermal cycling.

[0032] b. Core Strategy: Design Functionally Graded Coatings (FGC). From the copper substrate to the coating surface, a continuous change in composition ensures a smooth transition in the coefficient of thermal expansion. For example: Copper → Copper + Nickel → Nickel → Nickel + Ceramics → Ceramics. This greatly alleviates interfacial stress.

[0033] 4) Bonding performance between the coating and the copper plate To address performance issues, we need to start by addressing the root causes of the interface problems. a. Mechanical bonding reinforcement: The surface of the copper plate is roughened (e.g., sandblasted) before spraying, and micro-anchoring structures such as dovetail grooves may be processed.

[0034] b. Metallurgical bonding strengthening: Laser cladding or plasma transferred arc welding is used. This causes the coating material and the thin layer on the copper substrate surface to melt together, forming a strong metallurgical bond. The bonding strength is 2-5 times that of traditional spraying, but the process is complex and requires strict control of heat input to prevent the copper substrate from overheating.

[0035] c. Transition layer technology: Before spraying the working coating, a layer of nickel-aluminum or nickel-chromium alloy is first sprayed as a base coat. This layer undergoes an exothermic reaction during spraying and has good wettability with copper, forming a strong bonding interface.

[0036] The bonding performance of the coating is tested according to the national standard GB / T 8642-2002 "Determination of tensile bonding strength of thermal spray coating". The bonding strength of high-performance coatings should be above 50MPa.

[0037] Example 1 1. Performance-balanced design: Clearly define the core priorities of the coating. For example, if the primary goal is longevity and stability, thermal shock resistance and bond strength should be given top priority; if the goal is to enhance heat transfer, the coating thickness must be carefully controlled to balance thermal insulation.

[0038] 2. Example of a specific process path: 1) Surface preparation: Degreasing and sandblasting roughening of the hot surface of the copper plate.

[0039] 2) Spraying transition layer: A NiCr or NiAl bonding layer of about 50-100 micrometers is prepared by HVOF or atmospheric plasma spraying (APS).

[0040] 3) Spray coating working layer: HVOF spraying is used to spray a carefully designed Cr3C2-NiCr or WC-Co metal ceramic gradient coating, with the total thickness controlled between 0.3-0.8mm.

[0041] 4) Post-treatment: Laser remelting can be performed to eliminate layered structures and seal pores, or hot isostatic pressing (HIP) can be performed to further improve coating density and adhesion.

[0042] This invention addresses the pain points of copper cooling walls by developing a "coating + copper plate" type, which is mainly applied to the belly, waist and lower part of the furnace body of vanadium-titanium blast furnaces. These areas have high heat loads, thus enhancing the strength and deformation resistance of the cooling walls.

Claims

1. A cooling wall structure for a vanadium-titanium blast furnace, comprising a cooling wall (1) and cooling water pipes (2) embedded in the cooling wall (1), characterized in that: The cooling wall (1) is made of copper plate, and at least on the surface of the cooling wall (1) facing the vanadium-titanium blast furnace body, a wear-resistant and heat-insulating metal-ceramic composite layer (3) is applied.

2. The cooling wall for a vanadium-titanium blast furnace according to claim 1, characterized in that: The metal-ceramic composite layer (3) is a chromium carbide-based metal-ceramic composite layer, with nickel or cobalt used as the metal bonding phase between the chromium carbide-based metal and the ceramic.

3. The cooling wall for a vanadium-titanium blast furnace according to claim 1, characterized in that: After the chromium carbide-based metal-ceramic composite layer is laid, the arrangement structure is formed from the inside out as copper → copper + nickel → nickel → nickel + ceramic → ceramic.

4. The cooling wall for a vanadium-titanium blast furnace according to claim 3, characterized in that: The metal-ceramic composite layer (3) is a tungsten carbide-based metal-ceramic composite layer, with nickel or cobalt used as the metal bonding phase between the tungsten carbide-based metal and the ceramic.

5. The cooling wall for a vanadium-titanium blast furnace according to claim 4, characterized in that: After the tungsten carbide-based metal-ceramic composite layer is laid, the arrangement structure is formed from the inside out as copper → copper + nickel → nickel → nickel + ceramic → ceramic.

6. The cooling wall for a vanadium-titanium blast furnace according to claim 2, 3, 4 or 5, characterized in that: Yttrium oxide, which stabilizes zirconium oxide, is also added to chromium carbide-based or tungsten carbide-based metal materials.

7. The cooling wall for a vanadium-titanium blast furnace according to claim 6, characterized in that: The metal-ceramic composite layer (3) also integrates fiber optic sensors for monitoring wall temperature and stress; and a remaining life monitor is also installed in the metal-ceramic composite layer (3).

8. A method for constructing a cooling wall for a vanadium-titanium blast furnace as described in claim 7, comprising a cooling wall inlaid with cooling water pipes, characterized in that: The construction method first cleans and roughens the hot surface of the copper plate, then sprays a NiCr or NiAl bonding layer onto the qualified hot surface of the copper plate to form a transition layer, then applies a Cr3C2-NiCr or WC-Co cermet gradient coating on the NiCr or NiAl bonding layer to form a working layer, and finally uses laser remelting to eliminate the layered structure and seal the pores, or performs hot isostatic pressing to improve the density and adhesion of the coating to complete the preparation of the cooling wall.

9. The construction method according to claim 8, characterized in that: While spraying the NiCr or NiAl bonding layer, the fiber optic sensor is laid into the NiCr or NiAl bonding layer at least. The thickness of the NiCr or NiAl bonding layer is between 50 and 100 micrometers, and the thickness of the Cr3C2-NiCr or WC-Co cermet gradient coating is between 0.3 and 0.8 mm.

10. The construction method according to claim 9, characterized in that: The roughening process is completed by sandblasting, the NiCr or NiAl bonding layer is completed by high-speed oxygen fuel spraying or atmospheric plasma spraying, and the Cr3C2-NiCr or WC-Co metal ceramic gradient coating is completed by high-speed oxygen fuel spraying.

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