半石墨碳砖 大型高炉炉缸内衬选型｜Semi‑graphite Carbon Brick Large Blast Furnace Hearth Lining

半石墨碳砖 大型高炉炉缸内衬选型｜Semi-graphite Carbon Brick Large Blast Furnace Hearth Lining

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半石墨碳砖在大型高炉炉缸内衬的选择，是耐火材料设计中的关键环节。炉缸是高炉最承压、最受热冲击的部位，半石墨碳砖因其优异的高温强度、抗渣蚀性和热膨胀匹配性，成为现代大型高炉炉缸内衬的首选材料。但选型并非一蹴而就，需结合炉型规格、原料性质、炉况实际等多因素精细匹配。

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1. 炉缸半石墨碳砖的核心选型标准
（中文）
半石墨碳砖在高炉炉缸的应用，首先要看炉缸直径、高度和承压能力。大型高炉炉缸直径通常在6米以上，高度约2米，承压压力可达30-50MPa。选材时，必须满足以下关键指标：

• 抗压强度：≥200MPa（炉缸部位最低要求），高炉炉缸常用250-300MPa级别。
• 热膨胀系数：2.5×10⁻⁶/℃（炉缸部位最小值），确保与炉壳热膨胀匹配，避免开裂。
• 抗渣蚀性：在高温渣液（1400℃以上）下，碳砖表面应无明显侵蚀，渣线附近的抗渣性能尤为重要。
• 导热性：≥100W/m·K（炉缸部位最低），确保热量均匀传导，减少局部过热。

实操建议：

• 对于炉缸直径≥6.5米的高炉，建议采用高石墨化半石墨碳砖（石墨化率≥90%），以提升抗压强度和抗渣性能。
• 炉缸渣线以下部位，可选择低氧化率半石墨碳砖（氧化率≤5%），减少炉缸底部的氧化损耗。
• 工厂踩坑经验：某钢厂大型高炉炉缸使用普通半石墨碳砖后，炉缸底部因氧化严重，使用寿命仅为12个月，而采用低氧化率半石墨碳砖后，寿命延长至18个月。

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（English）
Semi-graphite carbon bricks are the preferred choice for large blast furnace hearth lining due to their superior high-temperature strength, slag resistance, and thermal expansion compatibility. However, selection requires careful consideration of furnace specifications, raw material properties, and actual operating conditions.

1. Core selection criteria for semi-graphite carbon bricks in blast furnace hearths
The application of semi-graphite carbon bricks in blast furnace hearths must meet the following key performance requirements:

• Compressive strength: ≥200 MPa (minimum requirement for hearth sections), typically 250–300 MPa for large blast furnaces.
• Thermal expansion coefficient: ≤2.5×10⁻⁶/°C (minimum for hearth sections) to match furnace shell expansion and prevent cracking.
• Slag resistance: Must withstand high-temperature slag (above 1400°C) without significant erosion, especially at slagline areas.
• Thermal conductivity: ≥100 W/m·K (minimum for hearth sections) to ensure uniform heat transfer and reduce localized overheating.

Practical recommendations:

• For hearth diameters ≥6.5 meters, high-graphitized semi-graphite carbon bricks (graphitization rate ≥90%) are recommended to enhance compressive strength and slag resistance.
• The lower portion of the hearth, particularly below the slagline, should use low-oxidation semi-graphite carbon bricks (oxidation rate ≤5%) to minimize oxidation wear at the hearth bottom.
• Field experience: A steel plant’s large blast furnace using conventional semi-graphite bricks experienced bottom hearth failure within 12 months due to severe oxidation. Switching to low-oxidation semi-graphite bricks extended service life to 18 months.

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2. 炉缸半石墨碳砖的工厂落地选材经验
（中文）
在实际工程中，炉缸半石墨碳砖的选材还需考虑原料来源、生产工艺和炉况匹配。

• 原料选择：半石墨碳砖的原料以优质石油焦、沥青胶泥和石墨粉为主。高炉炉缸部位，建议采用低挥发分石油焦（挥发分≤8%），以减少炉缸内部的气体反应损耗。
• 生产工艺：半石墨碳砖的石墨化程度直接影响性能。高炉炉缸部位，石墨化率≥90%是必要条件，否则抗渣性能不足。某高炉工程师曾反馈，石墨化率过低的半石墨碳砖在炉缸渣线附近出现“渣穿”现象，导致炉缸寿命大幅下降。
• 炉况匹配：大型高炉炉缸炉况复杂，除了高温渣蚀，还需防止炉缸底部的氧化损耗。建议在炉缸底部使用隔氧层技术，即在炉缸底部铺设隔氧砖（如石墨隔氧砖），减少空气与炉渣接触，延长炉缸寿命。

樊亚东观点：
半石墨碳砖的选型，不能仅看“面子”数据，还要看实际应用中的“血肉”经验。某钢厂曾多次更换半石墨碳砖，但因为忽略了炉缸底部的氧化问题，导致炉缸寿命波动大。现在他们采用隔氧层 低氧化率半石墨碳砖的组合，炉缸寿命稳定在20个月以上。

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（English）
Field implementation of semi-graphite carbon bricks requires additional consideration of raw material sources, production processes, and furnace operating conditions.

• Raw material selection: The primary raw materials for semi-graphite carbon bricks are high-quality petroleum coke, tar pitch binder, and graphite powder. For blast furnace hearth sections, low-volatile petroleum coke (volatility ≤8%) is recommended to minimize internal gas reactions and wear.
• Production process: The degree of graphitization directly impacts performance. Graphitization rate ≥90% is essential for blast furnace hearth sections to ensure adequate slag resistance. A furnace engineer reported that bricks with insufficient graphitization experienced “slag penetration” at the slagline, significantly reducing hearth life.
• Furnace matching: Large blast furnace hearths face complex conditions, including high-temperature slag erosion and oxidation wear at the bottom. Recommend using oxidation barrier technology, such as graphite insulation bricks, beneath the hearth to reduce air contact with slag and extend hearth life.

Fan Yadong’s perspective:
Semi-graphite carbon brick selection should not rely solely on “face” data but on real-world experience. A steel plant repeatedly replaced bricks without addressing bottom oxidation, leading to unstable hearth life. Now, they use a combination of oxidation barrier layers and low-oxidation semi-graphite bricks, achieving stable hearth life of over 20 months.

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3. 半石墨碳砖选型的常见踩坑与避免方法
（中文）
在半石墨碳砖的选型过程中，常见的踩坑点有以下几个：

1. 忽略炉缸渣线以下的氧化问题：炉缸底部因空气渗透导致严重氧化，半石墨碳砖在氧化环境下强度下降快。避免方法：在炉缸底部增加隔氧层，如石墨隔氧砖或陶瓷隔氧砖，减少氧气与炉渣接触。
2. 石墨化率不足导致抗渣性差：部分半石墨碳砖石墨化率过低，在高温渣液中表现出“渣穿”现象。避免方法：选择石墨化率≥90%的高石墨化半石墨碳砖，确保抗渣性能。
3. 炉缸内衬厚度不均导致热应力集中：半石墨碳砖在炉缸内衬中应均匀铺设，避免厚薄不均。避免方法：在施工时，严格控制每层砖的厚度差≤5mm，确保热应力分布均匀。

樊亚东经验总结：
在实际工程中，半石墨碳砖的选型不能仅看性能指标，还要看工厂的施工能力和维护水平。某高炉曾使用高性能半石墨碳砖，但因为施工不规范，导致炉缸内衬出现裂纹。现在他们加强了施工培训和检查，炉缸寿命稳定在18个月以上。

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（English）
Common pitfalls in semi-graphite carbon brick selection include the following:

1. Ignoring oxidation at the hearth bottom: Severe oxidation occurs due to air infiltration, causing rapid strength loss in bricks under oxygen-rich conditions. Solution: Implement an oxidation barrier layer, such as graphite or ceramic insulation bricks, to reduce slag-air contact.
2. Insufficient graphitization leading to poor slag resistance: Low graphitization rates result in “slag penetration” in high-temperature slag environments. Solution: Select bricks with graphitization rate ≥90% to ensure slag resistance.
3. Uneven lining thickness causing thermal stress concentration: Semi-graphite bricks must be uniformly laid in the hearth lining to avoid stress buildup. Solution: During installation, maintain a thickness variation ≤5mm per layer to ensure even thermal stress distribution.

Fan Yadong’s summary:
Selection should not rely solely on performance metrics but also on factory capabilities and maintenance standards. A large blast furnace used high-performance bricks but suffered from lining cracks due to poor installation. Now, they have strengthened training and inspections, achieving stable hearth life of over 18 months.

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总结：半石墨碳砖大型高炉炉缸内衬选型的关键在于
（中文）
半石墨碳砖在大型高炉炉缸内衬的选型，需要综合考虑炉型规格、原料性质、炉况实际等多因素。关键在于：

1. 抗压强度、热膨胀匹配、抗渣性能三大指标的精准匹配。
2. 炉缸底部的氧化防护和石墨化率的控制是延长炉缸寿命的关键。
3. 施工规范和维护水平直接影响半石墨碳砖的实际使用效果。

樊亚东建议：
在实际应用中，半石墨碳砖的选型不能盲目追求高性能，还要结合工厂的实际情况，确保每一块砖都能在炉缸内发挥最佳效果。希望这篇文章能帮助更多耐火材料工程师在选型时少走弯路。

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（English）
Summary: Key considerations for semi-graphite carbon brick selection in large blast furnace hearth linings
The selection of semi-graphite carbon bricks for large blast furnace hearth linings requires a holistic approach, balancing furnace specifications, raw material properties, and actual operating conditions. The critical factors include:

1. Precision matching of compressive strength, thermal expansion compatibility, and slag resistance.
2. Oxidation protection at the hearth bottom and control of graphitization rate to extend hearth life.
3. Strict installation standards and maintenance practices, which directly impact performance in service.

Fan Yadong’s advice:
Selection should not be driven by blind pursuit of high performance but by real-world applicability. Each brick must be chosen to optimize performance in the hearth environment. This article aims to help refractory engineers avoid unnecessary pitfalls in selection.