Blast furnace lining with improved thermal conductivity and service life

Abstract

A blast furnace lining includes an upper furnace body section, a middle furnace belly section, and a hearth section, and may include a bottom pad section. At least a portion of the hearth section includes an outer layer made of a first refractory material with a thermal conductivity of not less than 16 W / m·K, and an inner layer made of a second refractory material with an iron erosion index of less than 1% and a thermal conductivity of not less than 8 W / m·K. The invention also provides a blast furnace lined with the lining and a method for lining a blast furnace.

Description

Technical Field

[0001] This invention relates to a blast furnace refractory lining with improved thermal conductivity and service life, a blast furnace containing the lining, and a method for lining a blast furnace. Background Technology

[0002] The lining of a blast furnace, especially the lining of the hearth, is made of refractory materials and is in constant contact with high-temperature gas, molten slag, and molten iron, typically operating in a high-temperature environment above 1550°C for 24 hours a day. The blast furnace hearth is a thick-walled structure, usually constructed of carbonaceous refractory bricks. Carbon and graphite are widely recognized as suitable structural materials for preparing refractory bricks due to their non-wetting properties by molten iron.

[0003] To prevent burn-through accidents in the refractory hearth, a protective layer, such as an alumina-based refractory material layer, can be laid on the surface of the refractory bricks. A conventional lining comprises cooling walls and / or bricks made of carbonaceous or carbon-ceramic materials. Numerous joints exist between the cooling walls and bricks, and between the lining and the adjacent blast furnace hearth in such linings. During blast furnace operation, these joints can deteriorate relatively quickly, leading to the leakage of alkaline vapors, carbon monoxide, and other reactive substances, causing chemical erosion of the refractory bricks constituting the hearth. Although various protective grouting materials can be used to secure the joints, the service life of linings constructed with cooling walls and / or bricks remains limited.

[0004] To address the leakage problem associated with timber / brick linings, a seamless lining structure using castable refractory material has been developed. The castable refractory material can be injected into a temporary mold via pumping or other casting methods, defining a space adjacent to the blast furnace hearth. This mold must remain in place until the seamless refractory lining has solidified and hardened before removal. The mold can then be left in place until it is burned away by the molten iron being processed within the blast furnace. The mold can then be disassembled and removed, or left in place until burned away and consumed by the molten iron being processed within the blast furnace. However, because the seamless refractory lining is in continuous contact with the high-temperature gas, liquid slag, and molten iron (e.g., molten iron) within the blast furnace, it still requires periodic maintenance and / or replacement.

[0005] The blast furnace is a core piece of equipment in an integrated steel plant, used to reduce iron ore to iron. For example, the blast furnace charge may include iron ore, metallurgical coke, and limestone, added from the top of the furnace in block form and varying proportions. Hot air is introduced into the furnace through the tuyeres, contacting the descending charge and reacting chemically with the metallurgical coke to reduce the iron ore to iron. Molten iron and slag collect in the hearth and are discharged separately through different tapholes.

[0006] The design life of modern blast furnaces is typically from 5 to 15 years, depending on the furnace's size, structure, and operating conditions. To achieve the longest possible service life, the refractory lining of a blast furnace must be resistant to high-temperature corrosion, mitigate thermal expansion, prevent cracking, and resist alkali erosion. The blast furnace hearth, due to its contact with molten iron, slag, and alkalis, is prone to corrosion and usually requires a refractory lining with optimal corrosion resistance and thermal stress resistance. However, even the most durable refractory linings require frequent replacement under high-stress conditions. Summary of the Invention

[0007] This invention provides a blast furnace lining, a blast furnace with the blast furnace lining on its inner wall, and a method for constructing the blast furnace lining. The blast furnace lining has an upper furnace body section, a middle furnace belly (abdomen) section, and a lower hearth section, and may also include a hearth section. In this document, the "upper furnace body section" is defined as the portion of the lining that covers the blast furnace body, which generally occupies the upper third to upper half of the vertical height of the blast furnace inner wall, measured from the lowest point of the furnace dome to the bottom of the hearth. This area is the lowest temperature part of the blast furnace, typically ranging from below 200°C to approximately 800°C.

[0008] In this article, the "central belly (abdomen) section" is defined as the portion of the lining that covers the blast furnace belly or "abdomen," located below the furnace body, roughly one-quarter to one-third of the vertical height of the blast furnace inner wall. The blast furnace belly (abdomen) is typically the hottest area within the blast furnace. For example, the temperature within the belly (abdomen) can range from approximately 800°C to over 2000°C. In both the furnace body and belly sections, the temperature gradually increases as the burden descends and the reduction of iron ore to iron occurs.

[0009] In this article, the "lower hearth section" or "hearth section" is defined as the portion of the lining that covers the blast furnace hearth, located in the lowest area of ​​the blast furnace below the belly. The hearth occupies approximately one-fifth to one-third of the blast furnace's vertical height and may include the tuyeres and all the area below them. The typical temperature range within the hearth is from approximately 2000°C to approximately 1500°C, with a certain cooling trend from the tuyeres to the furnace bottom.

[0010] The “bottom pad section” of a blast furnace lining may include any (usually horizontal) portion of the lining that covers the hearth bottom (bottom pad).

[0011] The hearth section of the blast furnace lining can be designed with sufficient thermal conductivity to achieve rapid cooling of the high-temperature molten iron boundary layer within the blast furnace, thereby forming a solid boundary layer or "solidified iron layer" of molten iron on the surface of the blast furnace lining within the hearth. Once formed, this solid boundary layer protects the blast furnace lining from continuous erosion by high-temperature gas, molten slag, and hot iron within the blast furnace, thus significantly extending the service life of both the blast furnace lining and the blast furnace itself. This solid metallic boundary layer can form in the hearth section of the blast furnace, covering the lower hearth region of the lining and extending from the tuyeres to the furnace bottom (including the furnace bottom). The solid boundary layer protects the relevant areas of the lining from erosion caused by long-term direct contact between molten iron and slag.

[0012] To achieve the above objectives, at least a portion of the hearth section of the blast furnace lining may be provided with an outer layer (safety lining) made of a first refractory material with a thermal conductivity (measured within the range of 20℃-250℃) of not less than approximately 16 W / m·K; and an inner layer (working lining) made of a second refractory material with an iron erosion index of less than approximately 1% and a thermal conductivity (measured within the range of 20℃-250℃) of not less than approximately 8 W / m·K. The outer layer (safety lining) may be installed adjacent to the blast furnace cooling wall (cooling system), facilitating the transfer of cooling energy provided by the cooling water pipes within the cooling wall to the adjacent molten iron within the hearth through the inner layer (working lining). The blast furnace cooling wall is a cooling device installed between the blast furnace shell and the lining, adjacent to the furnace shell. To extend the service life of the blast furnace lining and the blast furnace itself, the second refractory material of the inner lining layer, in addition to having a low iron erosion index, should also possess a certain thermal conductivity.

[0013] In one embodiment, the blast furnace lining's bottom pad (bottom) section may also be provided with an outer layer (lower pad) made of a first refractory material or equivalent refractory material, whose thermal conductivity (measured within the range of 20℃-250℃) is not less than about 16 W / m·K; and an inner layer (upper pad) made of a second refractory material or equivalent refractory material, whose iron erosion index is less than about 1%, and whose thermal conductivity (measured within the range of 20℃-250℃) is not less than about 8 W / m·K. In this document, the term "layer" may refer to a single-layer structure or a structure of multiple adjacent layers made of the same refractory material.

[0014] The thermal conductivity of refractory materials can be measured according to the ASTmE1461-13 standard or the Chinese national standard GB / T22588-2008 formulated with reference to ASTmE1461-13, both of which are incorporated herein by reference. In the expression of thermal conductivity, "W" refers to watts, "m" refers to 1 meter thickness, and "K" refers to 1 Kelvin temperature. Since thermal conductivity varies with temperature, the values ​​described herein apply to a temperature range of 20°C to 250°C. In some embodiments, the thermal conductivity of the first refractory material may be no less than about 16 W / m·K, about 20 W / m·K, about 24 W / m·K, about 28 W / m·K, or about 32 W / m·K. Theoretically, there is no upper limit; in practical applications, the thermal conductivity of the first refractory material can reach up to about 60 W / m·K. In some embodiments, the thermal conductivity of the second refractory material may be no less than about 8 W / m·K, about 9 W / m·K, about 10 W / m·K, about 11 W / m·K, about 12 W / m·K or about 13 W / m·K, and may reach up to about 15 W / m·K.

[0015] Iron erosion resistance is an indicator of the durability of refractory linings, referring to the percentage of erosion over a specified period of time under specified test conditions. Iron erosion resistance can be measured according to the People's Republic of China National Standard GB / T24201-2009 "Test Method for Resistance to Molten Iron Erosion of Refractory Materials for Blast Furnaces" (released July 8, 2009). The test procedure of this standard is incorporated herein by reference and is summarized in the examples. In some examples, the iron erosion index of the second refractory material may be less than about 1.0%, about 0.8%, about 0.6%, about 0.4%, or about 0.3%.

[0016] An inner layer (working lining) made of a second refractory material is typically used to protect an outer layer (safety lining) made of a first refractory material from iron erosion. In some embodiments, the first refractory material may also possess excellent resistance to iron erosion. For example, the iron erosion index of the first refractory material may be less than about 1.0%, about 0.8%, about 0.6%, about 0.4%, or about 0.3%.

[0017] The chemical reaction that reduces iron ore to iron and the resulting heat release occur in the belly and hearth sections of the blast furnace. The lower hearth section of the blast furnace lining, and, where appropriate, the hearth pad (hearth) section, forms the aforementioned outer and inner refractory material structure, providing optimal heat dissipation for the blast furnace hearth, thereby forming a solidified metallic iron layer in the lower hearth section of the blast furnace lining. The formation of this solidified metallic iron layer, combined with the low erosion index of the second refractory material within the blast furnace hearth, extends the service life of both the blast furnace lining and the blast furnace itself.

[0018] The blast furnace lining is appropriately a seamless structure, meaning it can be continuous and uninterrupted, and there are no seams that would occur when using refractory bricks as the lining. The outer and inner layers of the lower hearth section of the blast furnace lining can be made of castable refractory materials, and can be formed by pumping or casting into molds, with the molds temporarily maintaining a certain distance from the blast furnace wall. The upper furnace body section and the middle belly (abdomen) section of the blast furnace lining can be prepared using conventional techniques and conventional refractory materials, as detailed below.

[0019] In one embodiment, the first refractory material used for lining the lower hearth section may have a composition comprising the following components in the indicated mass percentages:

[0020] Silicon carbide, comprising approximately 85% to 95% by mass;

[0021] Silica, comprising approximately 3% to approximately 10% by mass;

[0022] Alumina comprising approximately 0.5% to approximately 3% by mass;

[0023] Free carbon, comprising approximately 0.5% to approximately 3% by mass;

[0024] Iron oxide, calcium oxide and titanium oxide, comprising approximately 0.1% to approximately 1% by mass.

[0025] In one embodiment, the second refractory material used for lining the lower hearth section may have a composition comprising the following components in the indicated mass percentages:

[0026] Alumina comprising approximately 55% to approximately 90% by mass;

[0027] Silicon carbide, comprising approximately 10% to approximately 25% by mass;

[0028] Silica, comprising approximately 1% to approximately 15% by mass;

[0029] Titanium oxide comprising approximately 0.5% to approximately 3% by mass;

[0030] Free carbon, comprising approximately 0.5% to approximately 2% by mass;

[0031] Iron oxide and calcium oxide, accounting for approximately 0.1% to approximately 1% by mass.

[0032] Based on the above, one technical feature and advantage of the present invention is that it provides a blast furnace lining, comprising the following elements:

[0033] Upper furnace body section, middle furnace belly section and lower furnace hearth section;

[0034] The lower hearth section has at least a portion of an outer layer made of a first refractory material with a thermal conductivity of not less than 16 W / m·K and an inner layer made of a second refractory material with an iron erosion index of less than 1% and a thermal conductivity of not less than 8 W / m·K.

[0035] Another technical feature and advantage of the present invention is that it provides a blast furnace with a blast furnace lining, the blast furnace lining comprising:

[0036] Upper furnace body section, middle furnace belly section, lower furnace hearth section and furnace bottom pad section;

[0037] The lower hearth section has at least a portion of an outer layer made of a first refractory material with a thermal conductivity of not less than 16 W / m·K, and an inner layer made of a second refractory material with an iron erosion index of less than 1% and a thermal conductivity of not less than 8 W / m·K.

[0038] The chemical composition of the first refractory material includes:

[0039] Silicon carbide, comprising approximately 85% to 95% by mass;

[0040] Silica, comprising approximately 3% to approximately 10% by mass; and

[0041] Alumina comprising approximately 0.5% to approximately 3% by mass.

[0042] Another technical feature and advantage of the present invention is that it provides a blast furnace with a blast furnace lining, the blast furnace lining comprising the following elements:

[0043] Upper furnace body section, middle furnace belly section, lower furnace hearth section and furnace bottom pad section;

[0044] The lower hearth section has at least a portion of an outer layer made of a first refractory material with a thermal conductivity of not less than about 16 W / m·K, and an inner layer made of a second refractory material with an iron erosion index of less than about 1% and a thermal conductivity of not less than about 8 W / m·K.

[0045] At least a portion of the furnace bottom pad section is provided with an outer layer made of a first refractory material with a thermal conductivity of not less than about 16 W / m·K, and an inner layer made of a second refractory material with an iron erosion index of less than about 1% and a thermal conductivity of not less than about 8 W / m·K.

[0046] Another technical feature and advantage of the present invention is that it provides a method for lining a blast furnace, comprising the following steps:

[0047] The blast furnace lining, consisting of an upper furnace body section, a middle furnace belly section, a lower hearth section, and a furnace bottom pad section, is laid onto the inner surface of the blast furnace.

[0048] The lower hearth section has at least a portion of an outer layer made of a first refractory material with a thermal conductivity of not less than about 16 W / m·K, and an inner layer made of a second refractory material with an iron erosion index of less than about 1% and a thermal conductivity of not less than about 8 W / m·K.

[0049] Another technical feature and advantage of the present invention is that it provides a method for lining a blast furnace, comprising the following steps:

[0050] The blast furnace lining, consisting of an upper furnace body section, a middle furnace belly section, a lower hearth section, and a furnace bottom pad section, is laid onto the inner surface of the blast furnace.

[0051] The lower hearth section includes at least a portion thereof with an outer layer made of a first refractory material having a thermal conductivity of not less than approximately 20 W / m·K, and an inner layer made of a second refractory material having an iron erosion index of less than approximately 1% and a thermal conductivity of not less than approximately 8 W / m·K; and

[0052] The chemical composition of the first refractory material includes:

[0053] Silicon carbide, comprising approximately 85% to 95% by mass;

[0054] Silica, comprising approximately 3% to approximately 10% by mass; and

[0055] Alumina comprising approximately 0.5% to approximately 3% by mass.

[0056] Another technical feature and advantage of the present invention is that it provides a method for lining a blast furnace, comprising the following steps:

[0057] The blast furnace lining, consisting of an upper furnace body section, a middle furnace belly section, a lower hearth section, and a furnace bottom pad section, is laid onto the inner surface of the blast furnace.

[0058] The lower hearth section has at least a portion of an outer layer made of a first refractory material with a thermal conductivity of not less than about 16 W / m·K, and an inner layer made of a second refractory material with an iron erosion index of less than 1% and a thermal conductivity of not less than about 8 W / m·K.

[0059] At least a portion of the furnace bottom pad section is provided with a lower pad layer made of a first refractory material with a thermal conductivity of not less than about 16 W / m·K, and an upper pad layer made of a second refractory material with an iron erosion index of less than 1% and a thermal conductivity of not less than about 8 W / m·K.

[0060] The above and other features and advantages of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings. Attached Figure Description

[0061] Figure 1An embodiment of a blast furnace employing the blast furnace lining of the present invention is illustrated schematically;

[0062] Figure 2 for Figure 1 The enlarged view of the blast furnace hearth section shown highlights the structural features of the lower hearth section of the blast furnace lining.

[0063] Figure 3 The experimental setup for measuring iron erosion rate is illustrated schematically (see the embodiment for the experimental procedure);

[0064] Figure 4 This is a cross-sectional view of a refractory material sample used for iron erosion testing. Detailed Implementation

[0065] Figure 1 The illustration shows a blast furnace 10 of one embodiment, which is equipped with the blast furnace lining 30 of the present invention, and a portion of the lining may be reinforced with cooling plates 35. Figure 2 This is an enlarged view of the lower hearth section of the blast furnace 10. The blast furnace 10 includes the furnace top 12, furnace body 14, furnace belly (abdomen) 16, and hearth 18.

[0066] Typical charge for blast furnace 10 may include iron ore, metallurgical coke, and limestone, added in block form from the furnace dome 12 in different proportions. Oxygen-enriched hot air, exceeding 2000°C, is introduced into the blast furnace through tuyeres 24. The rising hot air contacts the descending charge in the furnace, causing its temperature to gradually increase as it descends, resulting in a chemical reaction with the metallurgical coke that reduces the iron ore to iron. The reduction process of iron ore to iron proceeds gradually from Fe₂O₃ to Fe₃O₄, then to FeO, then to Fe (solid), and finally to Fe (liquid), as the charge descends within blast furnace 10. For example, the temperature near the furnace dome 12 within the furnace body 14 gradually increases from approximately 160-180°C to approximately 1500°C or higher near the furnace belly 16, causing the charge to fluidize. Most of the chemical reactions that reduce iron ore to iron occur within the belly of the furnace (abdomen) 16, at temperatures ranging from approximately 1500°C to approximately 2000°C. The fully molten iron and slag descend into the hearth 18 and are discharged separately through the taphole. During the descent of the reduced iron from the belly of the furnace 16 to the hearth 18, the temperature remains at a relatively high level; in the lower region of the hearth 18, near the bottom pad (hearth bottom) 26, the temperature can be cooled to approximately 1500°C to 1550°C. Cooling within the hearth 18 can be achieved through a conventional cooling wall system 22 located within the hearth 18 adjacent to the blast furnace shell 20. Figure 2 The cooling wall system, located between the furnace shell 20 and the blast furnace lining 30, is used to facilitate the removal of heat from the hearth 18.

[0067] The blast furnace lining 30 includes an upper furnace section 32 that covers the portion of the blast furnace inner wall 20 corresponding to the blast furnace body 14. The upper furnace section 32 may be formed of a dense, high-alumina refractory material, such as a refractory material with an alumina mass fraction of not less than 60%. The high-alumina refractory material can be laid and formed within the furnace body 14 by shotcrete construction or other conventional techniques, and can be done after the middle section 34 and lower section 36 of the blast furnace lining 30 have been formed, as further described below. Since the upper furnace section 32 of the lining 30 corresponds to the area with the lowest temperature within the blast furnace, it is generally less susceptible to stress-induced wear than the middle section 34 and lower section 36 of the blast furnace lining 30.

[0068] The blast furnace lining 30 includes a central belly (belly) section 34 covering the portion of the blast furnace inner wall 20 corresponding to the belly 16 of the blast furnace 10, sometimes referred to as the "belly" region of the blast furnace 10. In one embodiment, the central belly section 34 of the blast furnace lining 30 may be formed of a high-alumina refractory material containing silicon carbide, the refractory material further comprising silicon carbide for heat conduction. In one embodiment, the refractory material may include:

[0069] Alumina comprising approximately 55% to approximately 90% by mass;

[0070] Silicon carbide, comprising approximately 10% to approximately 25% by mass;

[0071] Silica comprising approximately 1% to approximately 15% by mass; and

[0072] Optionally, titanium dioxide comprises approximately 0.5% to approximately 5% by mass.

[0073] The blast furnace lining 30 includes a hearth section 36 covering the portion of the blast furnace inner wall 20 corresponding to the hearth 18. The blast furnace lining 30 may also include a bottom pad (hearth) section 38 covering the hearth 26 of the hearth 18. Because the lower hearth section 36 and the bottom pad (hearth) section 38 of the blast furnace lining 30 are located in the blast furnace region (hearth region), which is most susceptible to wear and corrosion due to its long-term exposure to high-temperature molten iron, the lower hearth section 36 and the bottom pad (hearth) section 38 of the blast furnace lining 30 are typically the thickest parts. As previously mentioned, the blast furnace hearth 18 is equipped with a cooling wall cooling system 22, which uses cooling water pipes equipped with flowing coolant, such as water, to remove heat from the hearth. Figure 2 As shown, the cooling wall cooling system 22 relies on the thermal conductivity of the lower hearth section of the lining 30 to remove heat from the molten iron inside the blast furnace hearth 18. The hearth 18... Figure 2 A similar cooling system is provided inside or immediately adjacent to the furnace bottom 26 (not shown) and performs a similar function of removing heat from the high-temperature molten iron in the furnace bottom pad section 38 adjacent to the blast furnace lining 30.

[0074] According to the present invention, the performance of the blast furnace lining 30 can be improved by forming at least a portion of the hearth section 36 into an outer layer (safety lining) 40 comprising a first refractory material and an inner layer (working lining) 42 comprising a second refractory material. The outer layer (safety lining) 40 is placed immediately adjacent to the cooling wall cooling system 22 and is designed to have extremely high thermal conductivity. Therefore, the thermal conductivity of the first refractory material used to prepare the outer layer (safety lining) 40 is not less than about 16 W / m·K. In some embodiments, the thermal conductivity of the first refractory material may be not less than about 20 W / m·K, about 24 W / m·K, about 28 W / m·K, or about 32 W / m·K. From a performance perspective, there is theoretically no upper limit to the thermal conductivity of the first refractory material; for example, the first refractory material may have a thermal conductivity as high as about 60 W / m·K, about 56 W / m·K, or about 52 W / m·K.

[0075] The outer layer (safety lining) 40, with its high thermal conductivity, improves the heat transfer efficiency between the high-temperature molten iron in the hearth 18 and the cooling system 22 of the cooling wall. To effectively achieve this function, the inner layer (working lining) 42, in addition to having a low iron erosion index, indicating minimal erosion when exposed to molten iron for extended periods, should also possess certain thermal conductivity. Therefore, the thermal conductivity of the second refractory material used to form the inner layer (working lining) 42 can be no less than approximately 8 W / m·K, approximately 9 W / m·K, approximately 10 W / m·K, approximately 11 W / m·K, approximately 12 W / m·K, or approximately 13 W / m·K, and can reach up to approximately 15 W / m·K, approximately 14.5 W / m·K, approximately 14 W / m·K, or approximately 13.5 W / m·K. Furthermore, since the inner layer (working lining) 42 has the most direct contact with the molten iron, it must possess high erosion resistance to ensure the structural integrity of the hearth section 36 of the blast furnace lining 30. Therefore, the iron erosion index of the second refractory material can be lower than about 1%, about 0.8%, about 0.6%, about 0.4%, or about 0.3%.

[0076] The high thermal conductivity provided by the outer layer (safety lining) 40, combined with the certain thermal conductivity and low iron erosion index provided by the inner layer (working lining) 42, can significantly extend the overall service life of the blast furnace lining 30 and the blast furnace 10. This combination of properties distinguishes the blast furnace lining 30 from the blast furnace lining materials used in the hearth 18, which typically only provide either high thermal conductivity or a low iron erosion index, and cannot possess both simultaneously. In one embodiment, the first refractory material may also have an iron erosion index of less than about 1%, about 0.8%, about 0.6%, about 0.4%, or about 0.3%.

[0077] Table 1 shows the thermal conductivity and erosion index of two exemplary embodiments of the conductive refractory material composition of the present invention, labeled EXSR-1B (for the first refractory material) and TMS-1 (for the second refractory material), the specific components of which are detailed in the examples below. These properties are compared with six conventional refractory lining materials, which are typically used in single or multiple layers of the same material, rather than linings with different outer and inner layers of refractory material as described herein. In one embodiment of the invention, EXSR-1B can be used to form the outer layer (safety lining) 40 of the hearth region 36 of the refractory lining 30, and TMS-1 can be used to form the inner layer (working lining) 42. In another embodiment, EXSR-1B can be used to form the outer layer (safety lining) 40. 10 can be used to form the inner layer (working liner) 42.

[0078] Table 1

[0079]

[0080] *Tested according to Chinese National Standard GB / T22588-2008;

[0081] Tested according to Chinese National Standard GB / T24201-2009;

[0082] ***After being treated with carbon embedding, the samples were fired at 1400℃ for 3 hours before performance testing.

[0083] In one embodiment, the hearth section 38 of the refractory lining 30 may also employ a structure similar to the hearth section 36, including a double-material layer. For example... Figure 2 As shown, at least a portion, and adaptably all, of the furnace bottom pad (furnace bottom) section 38 may include an outer layer (lower pad layer) 44 made of a first refractory material or other refractory material that meets high thermal conductivity standards, and an inner layer (upper pad layer) 46 made of a second refractory material or other refractory material that meets certain thermal conductivity and low erosion index standards. As previously stated, the term "layer" is defined as a single-layer structure comprising a single refractory material or a structure of multiple adjacent layers of the same refractory material. Therefore, the terms "inner layer" or "upper pad layer" include... Figure 1 and Figure 2 The multi-layer (five-layer) structure shown is made of a second refractory material.

[0084] Similar to the lower hearth section 36, the high thermal conductivity lower lining 44 in the hearth section 38 improves the heat transfer efficiency between the high-temperature molten iron in the hearth 18 and the hearth cooling pipe system (not shown), which is placed within or adjacent to the blast furnace hearth pad 26, which may be formed from ASX60JS heat-resistant concrete insulating castable. For this purpose, the thermal conductivity of the first refractory material or its equivalent used to form the lower lining (safety lining) 44 is not less than about 16 W / m·K, adaptably not less than about 20 W / m·K, about 24 W / m·K, about 28 W / m·K, or about 32 W / m·K, and / or up to about 60 W / m·K, about 56 W / m·K, or about 52 W / m·K. To effectively perform its heat transfer function, the upper refractory layer (working lining) 46, in addition to possessing a low iron erosion index, should also have certain thermal conductivity. A low iron erosion index indicates minimal erosion when exposed to molten iron over a long period. Therefore, the thermal conductivity of the second refractory material or its equivalent used to prepare the upper refractory layer (working lining) 46 may be no less than about 8 W / m·K, about 9 W / m·K, about 10 W / m·K, about 11 W / m·K, about 12 W / m·K, or about 13 W / m·K, and / or may reach a maximum of about 15 W / m·K, about 14.5 W / m·K, about 14 W / m·K, or about 13.5 W / m·K. Furthermore, the iron erosion index of the second refractory material or its equivalent used to form the upper refractory layer (working lining) 46 may be less than about 1%, about 0.8%, about 0.6%, about 0.4%, or about 0.3%. As previously mentioned, the iron erosion index of the first refractory material used to form the lower cushion layer (safety liner) 44 may also be less than about 1%, about 0.8%, about 0.6%, about 0.4%, or about 0.3%.

[0085] After the double-layer refractory material structure of the present invention is adopted for the hearth section 36 and / or the bottom pad (hearth) section 38 of the blast furnace lining 30, the heat transfer efficiency is significantly improved, which helps to form a protective solid metal boundary layer, called the "solidified layer", in the area of ​​the hearth section 36 and / or the bottom pad (hearth) section 38 of the blast furnace lining 30 within the hearth 18. Due to the high heat dissipation rate of the affected area, the solidified layer is a relatively thin layer of solid iron and / or slag formed on the surface of the lining 30. The solidified layer can provide additional erosion protection for the affected areas of the blast furnace lining 30, thereby further extending the service life of the blast furnace lining 30 and the blast furnace 10.

[0086] The coverage area of ​​the protective solidified refractory layer depends partly on the area of ​​the first refractory material with high thermal conductivity and partly on the thermal conductivity of the first and second refractory materials. Under suitable operating conditions and with a reasonable design of the outer refractory material 40, the inner refractory material 42, the lower cushion layer 44, and the upper cushion layer 46, the solidified refractory layer can cover most or all of the area of ​​the blast furnace lining inside the hearth 18 that is continuously exposed to molten iron, and can also cover most or all of the hearth section 36 and the bottom section 38 of the blast furnace lining 30.

[0087] The large temperature variations and extremely high temperatures in certain parts of blast furnace 10 have led to the use of different alumina-containing refractory compositions in different areas of the refractory lining. For example, it is known that refractory lining materials with an alumina mass ratio of approximately 60% or less are used in the blast furnace body 14, while refractory lining materials with an alumina mass ratio exceeding 70% are used in the blast furnace belly 16 and hearth 18. The use of refractory materials with different compositions aims to achieve more uniform wear in different parts of the lining under both lower and higher temperature environments.

[0088] This invention breaks with traditional understanding by using a high thermal conductivity refractory material to replace the high-alumina content refractory lining inside the blast furnace hearth 18. This high thermal conductivity refractory material can have a low alumina content and is primarily composed of silicon carbide. By combining a high thermal conductivity first refractory material outer layer (safety lining) 40 or 44 with a second refractory material inner layer (working lining) 42 or 46 possessing certain thermal conductivity and a low iron erosion index, this invention achieves the performance advantages of combining two types of refractory materials in the combination of the hearth section 36 and the bottom pad (hearth) section 38 of the blast furnace lining 30. According to this invention, at least a portion of the hearth section 36 and / or at least a portion of the bottom section 38 of the blast furnace lining 30 may include the composite refractory layer structure. In other embodiments, the composite refractory layer structure may cover the entire hearth section 36 and / or the entire bottom pad (hearth) section 38 of the blast furnace lining 30.

[0089] In one embodiment, the first conductive refractory material may be primarily based on silicon carbide. For example, the mass percentage of silicon carbide in the conductive refractory material is not less than about 80%, about 85%, or about 88%, and / or can reach up to about 98%, about 95%, or about 92%.

[0090] In one embodiment, the first conductive refractory material may contain a low alumina content. For example, the mass percentage of alumina in the first refractory material may be as high as about 10%, about 5%, or about 3%, and / or as low as about 0.5%, about 1.0%, or about 1.5%.

[0091] In one embodiment, the first conductive refractory material may contain a low silica content. For example, the silica content in the first refractory material may be as high as about 15%, about 10%, or about 8% by mass, and / or as low as about 1%, about 3%, or about 5%.

[0092] In one embodiment, the first conductive refractory material may contain a small amount of free carbon. For example, the mass percentage of free carbon in the first refractory material is not less than about 0.5%, about 1.0%, or about 1.5%, and / or can be as high as about 3%, about 2.5%, or about 2%.

[0093] In one embodiment, the first high thermal conductivity refractory material may include:

[0094] Silicon carbide, comprising approximately 80% to approximately 98% by mass;

[0095] Silica comprising approximately 1% to approximately 15% by mass; and

[0096] Alumina comprising approximately 0.5% to approximately 10% by mass.

[0097] In one embodiment, the chemical composition of the first high thermal conductivity refractory material may include:

[0098] Silicon carbide, comprising approximately 85% to 90% by mass;

[0099] Silica, comprising approximately 3% to approximately 10% by mass; and

[0100] Alumina comprises approximately 1% to approximately 3% by mass.

[0101] In one embodiment, the second refractory material, possessing certain thermal conductivity and a low iron erosion index, may comprise alumina comprising approximately 50% to approximately 90% by weight. In another embodiment, the second refractory material may include:

[0102] Alumina comprising approximately 55% to approximately 90% by mass;

[0103] Silicon carbide, comprising approximately 10% to approximately 25% by mass;

[0104] Silica comprising approximately 1% to approximately 15% by mass; and

[0105] Optionally, titanium dioxide comprises approximately 0.5% to approximately 5% by mass.

[0106] In one embodiment, the hearth section 36 of the blast furnace lining 30 may be entirely formed of a first refractory outer layer 40 and a second refractory inner layer 42. In another embodiment, only a portion of the hearth section 36 may include a composite structure of the first refractory outer layer 40 and the second refractory inner layer 42, and the remaining portion of the hearth section 36 may be formed using a single second refractory layer. For example, the composite layer structure including the first refractory outer layer 40 and the second refractory inner layer 42 may cover approximately 25% to approximately 75%, approximately 30% to approximately 60%, or approximately 35% to approximately 50% of the vertical length of the lower hearth section 36 of the blast furnace lining 30, typically covering the area corresponding to the molten iron level within the hearth.

[0107] In general, due to prolonged exposure to the high-temperature molten iron within the hearth 18, the thickest portion of the blast furnace lining 30 can be located in the hearth section 36 and the hearth pad (hearth) section 38. For example, the total thickness of the lower hearth section 36 of the blast furnace lining 30 can be approximately 800 mm to approximately 2 m or 1 m to approximately 1.5 m. Where the outer layer 40 of the first refractory material and the inner layer 42 of the second refractory material coexist, the thickness of the outer layer 40 can be approximately 150 mm to approximately 400 mm or approximately 200 mm to approximately 300 mm.

[0108] The bottom lining (hearth) section 38 of the blast furnace lining 30 can have a total thickness of about 1.5m-3m or 2m-2.5m. Where a first refractory material lower lining layer 44 and a second refractory material upper lining layer 46 are present, the thickness of the lower lining layer 44 can be about 100mm to about 300mm or 150mm to about 250mm.

[0109] The upper hearth section 32 and the middle belly section 34 of the blast furnace lining 30 can be formed of conventional aluminum-based refractories in a single-layer structure, with a thickness less than that of the lower hearth section 36 of the blast furnace lining 30. These parts of the blast furnace lining can be formed by shotcrete construction or other conventional techniques. In one embodiment, the belly section 34 of the blast furnace lining 30 can be formed of an aluminum-based refractory material similar to the second refractory material used in the outer layer 40, but with slightly adjusted composition to improve thermal conductivity, erosion resistance, and adaptability to shotcrete construction requirements. Its chemical composition may include:

[0110] Alumina comprising approximately 55% to approximately 90% by mass;

[0111] Silicon carbide, comprising approximately 15% to approximately 30% by mass;

[0112] Fumed silica comprising approximately 1% to approximately 10% by mass; and

[0113] Spherical asphalt comprising approximately 0.5% to approximately 5% by weight.

[0114] In one embodiment, the furnace section 32 of the blast furnace lining 30 can be formed using an alumina-based refractory composition designed for shotcrete construction, but without significant silicon carbide content:

[0115] Aluminosilicate material comprising approximately 80% to 95% by weight (60% alumina content);

[0116] Calcined alumina comprising approximately 5% to approximately 15% by mass; and

[0117] Fumed silica comprising approximately 1% to approximately 10% by mass.

[0118] The belly (abdomen) section 34 and the body section 32 of the blast furnace lining 30 may have a thickness of about 100 mm to about 700 mm or about 200 mm to about 550 mm, with the top region of the body section 32 being relatively thin.

[0119] The present invention also relates to a blast furnace 10 having an inner wall, such as an inner wall 20, wherein at least a portion thereof is covered with the blast furnace lining 30 of the present invention described above. The blast furnace lining may be the blast furnace lining 30 described in any of the above embodiments; for example, the blast furnace lining may be any of the above-described blast furnace linings, including:

[0120] Upper furnace body section, middle furnace belly section and lower hearth section

[0121] The lower hearth section includes at least a portion of an outer layer made of a first refractory material with a thermal conductivity of not less than about 16 W / m·K, and an inner layer made of a second refractory material with an iron erosion index of less than 1% and a thermal conductivity of not less than about 8 W / m·K.

[0122] The present invention also relates to a method for lining a blast furnace, comprising the following steps:

[0123] The blast furnace lining, consisting of an upper furnace body section, a middle furnace belly section, a lower hearth section, and a furnace bottom pad section, is laid onto the inner surface of the blast furnace.

[0124] The lower hearth section has at least a portion of an outer layer (safety lining) made of a first refractory material with a thermal conductivity of not less than about 16 W / m·K, and an inner layer (working lining) made of a second refractory material with an iron erosion index of less than about 1% and a thermal conductivity of not less than about 8 W / m·K.

[0125] Furthermore, in the method of the present invention, the blast furnace lining may be the blast furnace lining 30 described in any of the above embodiments. For example, the blast furnace lining may be any of the above-described blast furnace linings, including:

[0126] Upper furnace body section, middle furnace belly section and lower furnace hearth section;

[0127] The lower hearth section has at least a portion of an outer layer (safety lining) made of a first refractory material with a thermal conductivity of not less than 16 W / m·K, and an inner layer (working lining) made of a second refractory material with an iron erosion index of less than 1% and a thermal conductivity of not less than 8 W / m·K.

[0128] Example

[0129] Reference Figure 1 and Figure 2 In the blast furnace 10 shown, the upper furnace section 32 of the blast furnace lining 30 is formed by sprayed concrete construction, using aluminum-based refractory materials produced by Magneco / Metrel. SX SC, its composition includes: a mullite / kyanite alumina-silica mixture (60% alumina, 40% silica) accounting for approximately 87% by mass, calcined alumina accounting for approximately 10% by mass, fumed silica accounting for approximately 2.5% by mass, and the remainder being cryolite, magnesia, and processing aids. The central belly (abdomen) section 34 of the blast furnace lining 30 is formed by shotcrete construction, using high-temperature resistant aluminum-based refractories manufactured by Magneco / Metrel. 10SC consists of approximately 76% bauxite / alumina mixture, approximately 20% silicon carbide, approximately 2.5% fumed silica, and the remainder being spherical pitch, magnesium oxide, and processing aids.

[0130] The lower 40% of the vertical length of the hearth section 36, corresponding to the height of the molten iron level, includes a composite (double-layer) refractory material structure, while the upper 60% uses a single second refractory material layer. The entire horizontal length of the hearth section 38 uses the aforementioned composite (double-layer) refractory material structure.

[0131] The outer layer 40 of the lower hearth section 36 of the blast furnace lining 30 and the lower pad layer 44 of the hearth section 38 are both formed by pump casting, using a high thermal conductivity primary refractory material with a thermal conductivity of 33-39 W / m·K. The following components are in the following mass percentages:

[0132] Silicon carbide: 89.22%;

[0133] Silica: 6.35%;

[0134] Free carbon: 1.85%;

[0135] Alumina: 1.60%;

[0136] Iron oxide: 0.32%;

[0137] Calcium oxide: 0.062%;

[0138] Titanium dioxide: 0.036%.

[0139] The outer layer (safety lining) 40 of the hearth section 36 has a thickness of approximately 150-200 mm. The lower pad layer (working lining) 44 of the bottom section 38 has a thickness of approximately 100-150 mm.

[0140] The remaining areas of the hearth section 36, including the inner layer (working lining) 42 and the single refractory layer area, and the upper pad (working lining) 46 of the hearth section 38, are all cast by pumping and use high-erosion-resistant aluminum-based refractories manufactured by Magneco / Metrel. It is formed in about 10 days, with an iron erosion index of about 0.2% and a thermal conductivity of about 11 W / m·K. Its composition includes: about 74% alumina by mass, about 17% silicon carbide by mass, about 6% silicon dioxide by mass, about 2% titanium dioxide by mass, and the remainder being processing aids.

[0141] The thickness of the inner layer (working lining) 42 and the single refractory material layer area of ​​the hearth section 36 is approximately 800-1000 mm. The thickness of the upper pad layer 44 of the furnace bottom pad (furnace bottom) section 38 is approximately 2 mm.

[0142] In the above two embodiments of blast furnace lining 30, the high thermal conductivity outer layer 40 of hearth section 36 and the high thermal conductivity lower pad layer 44 of bottom pad section 38 can both achieve rapid heat transfer, so that a solid metal boundary layer (solidified iron layer) is formed on the surface of hearth section 36 and bottom pad section 38, thereby protecting these areas from direct erosion by molten iron and slag.

[0143] Test method for iron erosion index (GB / T24201-2009)

[0144] The test method outlined in this standard is applicable to determining the resistance of blast furnace refractory materials to pig iron erosion at high temperatures. The test sample (specified below) is first weighed, then immersed in molten iron at 1425°C, stirred for 40 minutes under nitrogen protection, removed, and weighed again. The degree of erosion by the molten iron is determined by calculating the sample's mass loss.

[0145] A schematic diagram of the test device 100 is shown below. Figure 3 As shown in the diagram, markings 100-113 correspond to the following components arranged as illustrated:

[0146] 101 - Temperature Controller;

[0147] 102-Platinum-Rhodium-Platinum Thermocouple;

[0148] 103-Silicon molybdenum rod;

[0149] 104 - Counterweight;

[0150] 105 - Ventilation hose;

[0151] 106-Staff;

[0152] 107-Flow meter;

[0153] 108-Nitrogen Cylinder;

[0154] 109-Corundum connecting pipe;

[0155] 110 - Corundum crucible;

[0156] 111-Sample;

[0157] 112 - Molten Iron;

[0158] 113-Corundum tube.

[0159] Additional required equipment:

[0160] High-temperature furnace with an operating temperature of not less than 1500℃.

[0161] 15KW automatic thermostat.

[0162] An electronic balance with a maximum weighing capacity of 800g and an accuracy of 0.05g.

[0163] Rotor flowmeter with a flow range of 0L / min-10L / min.

[0164] Vernier calipers with a measuring range of 0mm-200mm and an accuracy of 0.03mm.

[0165] A forced-air drying oven with a temperature range of 0℃-300℃.

[0166] Bottled industrial nitrogen with a purity of 99.95%.

[0167] Sample preparation: Take two cylindrical refractory material samples, with a diameter of 30±0.5 mm and a height of 40±0.5 mm. Drill a 115mm opening in the center of each sample to create a sample as shown. Figure 3 and Figure 4 The sample 111 shown is an example. Figure 4 As shown, the opening 115 includes an upper portion 117 with a diameter slightly larger than 10 mm, located in the upper 15 mm region of the opening 115, and a lower portion 119 with a diameter slightly smaller than 8 mm, located in the lower 25 mm region of the borehole 115. The larger diameter portion of the upper portion 117 can accommodate the lower end of the corundum connecting tube 109, whose inner diameter is also approximately 8 mm. Besides fixing the sample 111, the corundum connecting tube 109 also serves as a ventilation channel. After weighing the initial mass of the sample 111, a phenolic resin mixed with carbonaceous mud is used to firmly bond the sample 111 to the corundum connecting tube 109. Figure 3 The bonded components are then placed in an electric furnace and dried at 120°C.

[0168] like Figure 3 As shown, the connecting pipe 109 should be long enough to be suspended on the support 106 above the high-temperature furnace. Weigh 1550±20g of steelmaking pig iron with a carbon content of 3.0%-4.0%, and heat the high-temperature furnace 100 to 1425℃ at a heating rate not exceeding 10℃ / min, for a total heating time of approximately 4 hours. As the pig iron melts at the high temperature, gradually pour it into the corundum crucible 110. After holding at this temperature for at least 10 minutes, insert the sample.

[0169] Next, under nitrogen protection, sample 111 is inserted into corundum crucible 110, suspending it 20 mm above the bottom of crucible 110, and then immersed in molten iron 112. A nitrogen flow rate of approximately 0.5 L / min is used. Nitrogen gas is introduced through nitrogen cylinder 108 via connecting pipe 109, keeping sample 111 immersed in molten iron at 1425°C for 40 minutes. Sample 111 is then removed from the molten iron and cooled with water. After cooling, sample 111 is dried, and any residual iron beads on the surface are removed. The final mass of sample 111 is weighed and compared with the initial mass to calculate the mass loss caused by iron erosion.

[0170] Repeat the test for each of the two samples, and average the results to determine the percentage of iron erosion rate of the refractory material, keeping the percentage of iron erosion rate to one decimal place.

[0171] The embodiments of the present invention described herein are merely illustrative and various modifications and improvements can be made without departing from the spirit and scope of the invention. The scope of protection of the present invention is defined by the appended claims, and all modifications falling within the meaning and equivalent scope of the claims should be included within the scope of protection of the present invention.

Claims

1. A blast furnace lining, comprising: Upper furnace body section, middle furnace belly section, and lower furnace hearth section; The lower furnace hearth section includes at least a portion of an outer layer made of a first refractory material and an inner layer made of a second refractory material. The thermal conductivity of the first refractory material is not less than about 16 W / m·K, and the iron erosion index of the second refractory material is less than about 1%, and the thermal conductivity is not less than about 8 W / m·K.

2. The blast furnace lining according to claim 1, wherein, The thermal conductivity of the first refractory material is not less than about 20 W / m·K.

3. The blast furnace lining according to claim 1, wherein, The thermal conductivity of the first refractory material is not less than about 24 W / m·K.

4. The blast furnace lining according to claim 1, wherein, The thermal conductivity of the first refractory material is not less than about 28 W / m·K.

5. The blast furnace lining according to claim 1, wherein, The thermal conductivity of the first refractory material is not less than about 32 W / m·K.

6. The blast furnace lining according to claim 1, wherein, The iron erosion index of the second refractory material is less than about 0.8%.

7. The blast furnace lining according to claim 1, wherein, The iron erosion index of the second refractory material is less than about 0.6%.

8. The blast furnace lining according to claim 1, wherein, The iron erosion index of the second refractory material is less than about 0.4%.

9. The blast furnace lining according to claim 1, wherein, The iron erosion index of the first refractory material is less than about 1.0%.

10. The blast furnace lining according to claim 1, wherein, The thickness of the outer layer is approximately 150 mm to approximately 300 mm.

11. The blast furnace lining according to claim 1, wherein, The thickness of the outer layer is approximately 200 mm to approximately 250 mm.

12. The blast furnace lining according to claim 1, wherein, The thickness of the inner layer is approximately 700 mm to approximately 1.1 m.

13. The blast furnace lining according to claim 1, wherein, The thickness of the inner layer is approximately 800 mm to approximately 1.0 m.

14. The blast furnace lining according to claim 1 further includes a furnace bottom pad section, wherein, The furnace bottom pad section includes a lower pad layer made of the first refractory material and an upper pad layer made of the second refractory material.

15. The blast furnace lining according to claim 14, wherein, The thickness of the underlay layer is approximately 50 mm to approximately 200 mm.

16. The blast furnace lining according to claim 14, wherein, The thickness of the underlay layer is approximately 100 mm to approximately 150 mm.

17. The blast furnace lining according to claim 14, wherein, The upper cushion layer comprises multiple layers of the second refractory material.

18. The blast furnace lining according to claim 14, wherein, The thickness of the upper cushion layer is approximately 1.6m to approximately 2.4m.

19. The blast furnace lining according to claim 14, wherein, The thickness of the upper cushion layer is approximately 1.8m to approximately 2.2m.

20. The blast furnace lining according to claim 1, wherein, The first refractory material includes: Silicon carbide, comprising approximately 80% to approximately 98% by mass; Silica comprising approximately 1% to approximately 15% by mass; and Alumina comprising approximately 0.5% to approximately 10% by mass.

21. The blast furnace lining according to claim 1, wherein, The first refractory material includes: Silicon carbide, comprising approximately 85% to 95% by mass; Silica, comprising approximately 3% to approximately 10% by mass; and Alumina comprises approximately 1% to approximately 3% by mass.

22. The blast furnace lining according to claim 1, wherein, The second refractory material includes: Alumina comprising approximately 55% to approximately 90% by mass; Silicon carbide, comprising approximately 10% to approximately 25% by mass; Silica comprising approximately 1% to approximately 15% by mass; and Optionally, titanium dioxide comprises approximately 0.5% to approximately 3% by mass.

23. A blast furnace, wherein the inner surface of the blast furnace is covered with a blast furnace lining, the blast furnace lining comprising: Upper furnace body section, middle furnace belly section, lower furnace hearth section, and furnace bottom pad section; Wherein, at least a portion of the lower hearth section comprises an outer layer made of a first refractory material and an inner layer made of a second refractory material, wherein the thermal conductivity of the first refractory material is not less than about 20 W / m·K, and the iron erosion index of the second refractory material is less than about 1%, and its thermal conductivity is not less than about 8 W / m·K; and The first refractory material includes: Silicon carbide, comprising approximately 85% to 95% by mass; Silica, comprising approximately 3% to approximately 10% by mass; and Alumina comprises approximately 0.5% to approximately 3% by mass.

24. The blast furnace according to claim 23, wherein, The second refractory material includes: Alumina comprising approximately 55% to approximately 90% by mass; Silicon carbide, comprising approximately 10% to approximately 25% by mass; Silica comprising approximately 1% to approximately 15% by mass; and Optionally, titanium dioxide comprises approximately 0.5% to approximately 5% by mass.

25. A blast furnace, wherein the inner surface of the blast furnace is covered with a blast furnace lining, the blast furnace lining comprising: Upper furnace body section, middle furnace belly section, lower furnace hearth section, and furnace bottom pad section; Wherein, at least a portion of the lower hearth section comprises an outer layer made of a first refractory material and an inner layer made of a second refractory material, wherein the thermal conductivity of the first refractory material is not less than approximately 16 W / m·K, and the iron erosion index of the second refractory material is less than approximately 1%, and its thermal conductivity is not less than approximately 8 W / m·K; and At least a portion of the furnace bottom pad section includes a lower pad layer made of a first refractory material and an upper pad layer made of a second refractory material, wherein the thermal conductivity of the first refractory material is not less than about 16 W / m·K, the iron erosion index of the second refractory material is less than about 1%, and the thermal conductivity is not less than about 8 W / m·K.

26. The blast furnace according to claim 25, wherein, The second refractory material includes: Alumina comprising approximately 55% to approximately 90% by mass; Silicon carbide, comprising approximately 10% to approximately 25% by mass; Silica comprising approximately 1% to approximately 15% by mass; and Titanium dioxide, comprising approximately 0.5% to approximately 5% by mass.

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