骨料浸渍氧化铝浆体对高炉炭砖显微结构和性能影响

针对炭砖为主要原料电煅煤的多孔结构,采用真空浸渍浆体方法对电煅煤骨料进行处理来改善骨料的致密度,从而优化炭砖的微孔结构,提高炭砖性能.首先对电煅煤骨料进行真空浸渍氧化铝浆体处理,得到浸渍氧化铝电煅煤骨料(以下简称浸渍骨料),然后将浸渍骨料取代电煅煤骨料引入到炭砖中,借助场发射扫描电镜、压汞仪和CT扫描仪等研究了浸渍骨料对高温热处理后炭砖显微结构、微孔结构和性能的影响.结果表明:通过真空浸渍氧化铝方法,氧化铝填充进电煅煤骨料的开口气孔和裂缝中,使骨料更加致密.将浸渍骨料引入到炭砖中,炭砖经不同温度处理后的性能得到明显改善,如经1400℃处理后炭砖的耐压强度提高近50％,平均孔径降低至73 nm,<1μm孔容积率达到80％左右.炭砖性能的改善主要与引入更加致密的浸渍骨料和形成更多的原位陶瓷相有关.     

添加碳化硅对电煅煤基高炉炭砖显微结构和性能的影响

采用不同粒度碳化硅部分取代高炉炭砖中的电煅煤骨料,借助X射线衍射仪、场发射扫描电镜、能谱仪以及激光导热仪等研究了碳化硅的引入对高温焙烧后高炉炭砖物相组成、显微结构和导热系数等性能的影响,并使用支持向量机回归建模算法建立了炭砖导热系数的数学模型,分析了各因素对炭砖导热系数影响程度.结果表明:碳化硅的加入可促进炭砖基体内原位陶瓷相AlN和β-SiC晶须的生成,进而有助于提高炭砖的耐压强度、导热系数和抗铁水侵蚀性能;由支持向量机建模分析得知,大粒度碳化硅的加入量和焙烧温度对导热系数提高的影响较为明显,适当增大大粒度碳化硅的含量并提高焙烧温度有可能进一步提高炭砖的导热系数.     

支持向量机算法对电锻煤基炭砖导热性能的优化及预报

导热系数是评价高炉炭砖性能的重要指标之一.本工作在传统电煅煤基炭砖的基础上,使用人造石墨逐步替换电锻煤细粉与骨料,系统研究了人造石墨引入量、焙烧温度等因素对炭砖导热性能的影响,并使用支持向量机回归建模分析算法建立了炭砖导热系数的数学模型.结果表明,人造石墨的加入有助于提升炭砖的导热系数,并降低导热性能的各向异性,但会影响炭砖的抗铁水溶蚀性能;由支持向量机建模分析得知,石墨含量与气孔直径对导热系数提高的影响较为明显;借助该建模方法获得了炭砖导热系数的预报拟合公式,该公式具有较高精度,可用于炭砖导热系数的优化与预报.     

模压成型高炉炭砖的研制及应用

为了提高国产高炉炭砖的质量,通过设计并引进模压成型设备、严格控制炭砖的模压成型工艺参数,研制了模压成型高炉炭砖.介绍了模压成型设备的特点,并从原料选择、颗粒级配与配方组成和模压成型参数3方面阐述了模压成型炭砖的工艺控制.研制的模压成型炭砖经检测,其性能指标已完全达到进口炭砖的水平,满足大型高炉的使用需求和寿命要求.     

无烟煤石墨化的研究

以宁夏、山西、贵州、云南和越南鸿基5种不同产地的无烟煤为原料,研究了无烟煤石墨化的机理;同时对5种石墨化煤样进行了工业分析和X射线衍射分析,还对用5种石墨化煤作成的炭砖小样进行了全面的性能分析。结果发现,经高温处理后无烟煤是可以石墨化的,但石墨化煤与人造石墨又有区别;石墨化煤与气煅煤和电煅煤相比,性能质量明显改善,灰分、硫分和电阻率均降低,真密度提高;用石墨化煤作成的炭砖小样,除了抗压强度有所降低之外,其他性能都得到了显著改善,尤其是导热系数和抗碱性的提高,这对于提高高炉炭砖的质量有利的。     

微孔自焙炭砖的研制

在自焙炭砖生产、制作成功经验的基础上,以优质低灰高温电煅烧无烟煤为主要原料,以树脂、煤沥青的混合物为结合剂,加入适量的添加物,研制出焙烧温度低、透气度低、耐碱性能、抗铁水渗透及熔蚀性能优良的微孔自焙炭砖。     

超细微晶石墨对电煅煤基高炉炭砖显微结构和性能的影响

以电煅煤和活性α-Al2 O3微粉为主要原料,硅粉和铝粉为添加剂,在埋碳条件下经1200℃和1400℃焙烧处理后制备出电煅煤基高炉炭砖(以下简称炭砖).在炭砖中添加超细微晶石墨,借助X射线衍射仪、场发射扫描电子显微镜、激光导热仪和压汞仪研究了超细微晶石墨的引入对炭砖物相组成、显微结构、导热性能及孔结构的影响,并与引入相同量鳞片石墨的试样作对比.结果表明:实验所用超细微晶石墨晶粒尺寸细小,并且呈现出薄片状结构,与电煅煤相比具有更高的反应活性.在炭砖中引入超细微晶石墨,促进了材料中碳化硅晶须的生成,提高了材料的耐压强度和导热系数,增大了材料中<1μm气孔的孔容积率.与添加相同含量鳞片石墨的试样相比,含超细微晶石墨试样的导热系数和平均孔径与其相当,耐压强度更优,在炭砖中具有很好的应用前景.     

新型微孔炭砖的试制

本文介绍了炼铁高炉用新型微孔炭砖的试制概况。选用宁夏优质无烟煤经过电煅烧，原料配比中以电煅煤和石墨及部分添加剂为骨料，煤沥青作粘结剂试制出品质优良的新型微孔炭砖，对电煅烧工艺操作控制，本文给出了电阻率依赖于排料量和调整功率的回归方程。指出在稳定其电器参数条件下，控制好排料量是保证电煅烧无烟煤质量的主要因素。在微孔炭砖性能论述中，还给出了微孔炭砖的抗碱性依赖于石墨含量，炭砖的抗压强度依赖颗粒抗压碎强度，平均导热系数依赖石墨含量和石墨与焙烧温度交互作用的三个回归方程。同时还指出，微孔炭砖的抗压强度不仅受颗粒抗压碎强度的控制，而且还受焙烧过程中粘结剂沥青的结焦率所控制，因此，又给出了焙烧中沥青的结焦率依赖于粉子纯度、沥青用量、粉纯与沥青交互作用的回归方程。指出沥青与粉纯交互作用是影响焙烧结焦率的主要因素。微孔炭砖微孔形成的最低反应温度和最佳反应温度可由抗碱性和微孔容积依赖于焙烧温度的经验公式求出。同时还就兰炭试制的微孔炭砖质量指标与国内外优质炭砖实际指标做了对比。     

热压小炭砖的研制及其在高炉上的应用

在宝钢高炉对比应用结果表明,热压小炭砖炉缸优于大块炭砖和陶瓷杯炉缸。对热压小炭砖的研制情况进行介绍,包括原料选择、工艺特点和使用设备等。与美国Graf Tech热压小炭砖的对比研究表明:国产热压小炭砖在密度、强度、抗氧化性、抗铁水熔蚀性等方面优于Graf Tech热压小炭砖,在高炉上使用效果良好。     

高炉用热模压炭砖

分析了高炉炭砖的损毁机理，对用热模压工艺制备的炭砖进行了研究。研究表明，采用热模压工艺制备的炭砖气孔为闭合微孔，选择适当的加压曲线和电流密度等工艺参数能制备出高导热、低渗透率、抗碱侵蚀性良开的炭砖。     

两种不同铁水熔蚀炭砖微观结构分析

为提高高炉炭砖的抗铁水熔蚀性,对两种不同铁水熔蚀性炭砖进行了岩相和电子显微镜分析.炭砖的微观结果分析表明,无烟煤基质的炭砖抗铁水熔蚀性优于在原料中添加石墨的炭砖;往基质中加入Al_2O_3可大为改善炭砖的扰铁水熔蚀性;工艺上使Al_2O_3均匀分布是提高炭砖抗铁水熔蚀性的重要措施.     

不锈钢冶炼用铁水包Al2O3-SiC-C内衬砖的性能与侵蚀机理

铁水包内衬材料长期服役于间隔周期较长的高、低温交替环境,极易发生剥落与侵蚀损毁。为了探索影响铁水包内衬材料使用寿命的主要因素,对市面上四种铁水包Al₂O₃-SiC-C内衬砖的化学成分、物相组成、物理性能和微观结构进行了分析,并以高炉渣为侵蚀介质,重点研究了不锈钢冶炼用铁水包Al₂O₃-SiC-C内衬砖的侵蚀机理。结果表明:铁水包Al₂O₃-SiC-C内衬砖中Al₂O₃含量越高,高温下制品的液相量越低,越有利于提高耐火砖的高温力学性能;随着含碳量的增加,铁水包Al₂O₃-SiC-C内衬砖的抗渣性得到明显改善,但抗氧化性及高温抗折强度呈下降趋势;高炉渣中CaO、MgO向耐火砖中渗透,与耐火砖中的Al₂O₃、SiO₂发生反应形成高熔点的镁铝尖晶石及低熔点的钙长石等,生成的低熔相会加剧耐火砖的侵蚀。     

模铸用高铝质流钢砖的显微结构分析

选取市场上模铸用高铝质流钢砖与用后残砖作为研究对象,通过检测不同高铝质流钢砖的理化性能,对比其使用前后的显微结构变化,进一步探讨模铸过程中高铝质流钢砖的显微结构对钢铁产品质量的影响。结果表明:由于显气孔率较大、结构比较疏松、烧结不致密等特性,高铝质流钢砖在经受钢水冲刷时,钢水容易渗透至高铝质流钢砖内部,加速其损毁;其次,高铝质流钢砖与钢水发生物理化学反应后在其表面生成低熔点物,使钢水中产生夹杂物,影响钢铁产品的质量。     

气化炉用后高铬砖的渣蚀机理

采用扫描电镜和XRD等分析方法,对石油焦气化炉和水煤浆气化炉用后高铬砖及渣蚀试验砖的显微结构进行了观察与分析。根据高铬砖显微结构变化,研究了在不同气化炉内高铬砖受熔渣侵蚀损毁的机理。结果表明:石油焦气化炉用高铬砖中的Cr2O3与熔渣中的V2O5接触反应,在低温下形成液相而被熔蚀,是其蚀损的主要原因;水煤浆气化炉用高铬砖蚀损的主要原因是Cr2O3在熔渣里的溶解和ZrO2的熔蚀;LIRR-HK95砖由于成分和结构的优化,抗石油焦渣侵蚀性能好。     

Study on Microstructure and Slag Corrosion Mechanism of High Chrome Bricks for Gasifier

1 Introduction The gasifier like Texaco style is of important tech- nical equipment for ammonia synthesis and production of carbamide, carbinol and ethylene etc. Due to differ- ent energy resource structure, petroleum coke is adopt- ed as rawmaterial in A…     

Slag erosion-resistant coating for periclase-magnesia-aluminum spinel brick

The magnesia-carbon bricks are used at the ladle slag line adds carbon to molten steel and thus has an adverse effect on the smelting process. Steel production enterprises hope to remove carbon from the ladle slag line. This study presents a Silica sol (SS)–magnesium aluminate spinel(MA) coating that can be applied to the surfaces of periclase–MA spinel brick (spinel brick) to improve their slag erosion resistance, facilitating the elimination of carbon from the ladle slag line. The slag corrosion resistance mechanism of a spinel brick covered with the SS–MA coating was analyzed through scanning electron microscopy and simulation using FactSage software. The results show that increasing the SS content (C_SS) led to the formation of fine cracks during the coating-drying process and was detrimental to the slag erosion resistance of the coating. The optimum C_SS was 20%. In the high-temperature slag erosion experiment, the MA in the coating was capable of forming solid solutions with Fe and Mn in the slag, and the nano-SiO₂ in the coating interacted with the slag, increasing the viscosity of the slag and reducing its penetration. In addition, the presence of the coating extended the penetration path of the slag and reduced the contact area between the slag and the spinel brick and their chances to undergo chemical reactions, thereby protecting the spinel brick from slag erosion. The coated spinel bricks outperformed the magnesia-carbon brick in terms of slag erosion resistance, providing a basis for selecting carbon-free refractory materials for the ladle slag line.     

四种不同产地无烟煤性能研究

对四种国产无烟煤的化学成分、氧化率和岩相结果进行了分析，以及用此四种无烟煤在相同工艺条件下制成的微孔炭砖试样进行了试验研究。结果表明，阳泉煤制成的微孔炭砖性能优良，且阳泉煤变质程度最好，是生产微孔炭砖最为理想的原料；宁夏太西煤只要控制好煅烧质量，也是生产微孔炭砖的优质原料。     

EXPERIMENTS IN DEAD-BURNING DOLOMITE AND MAGNESITE1

Stability of calcined dolomite; effect of fineness of raw material, nature of flux and temperature of burning .—Dolomite is difficult to dead-burn because the absorption of moisture from the air produces a gradual slacking due, probably, to the hydration of lime and various lime compounds, and this tends to cause disintegration. With all the fluxes tried, 100 mesh raw material gave greater resistance to slacking than 8 mesh size. This resistance decreased, however, with increasing temperature of calcining, by an amount which seems to depend on the silica and alumina content of the flux, being greatest for basic open hearth slag and kaolin, less for flue dust, and iron ore, and least for roll scale. The stability also varied with the proportions of flux used, being greater, as a rule, for smaller proportions. Shrinkage, porosity and vitrification of calcined dolomite; effect of flux and burning temperature .—The shrinkage and porosity curves for mixtures containing flue dust, iron ore or roll scale are very similar. The higher the proportion of flux, the lower the temperature required to get maximum shrinkage and minimum porosity. Kaolin and basic open hearth slag behaved peculiarly in that vitrification depended more on the burning temperature than on the proportion of flux used. Experiments in making dolomite brick .—It was found that ageing of the wet calcined material was necessary to prevent cracking of the bricks upon drying. With 5 per cent MgCl₂ as binder, comparatively strong brick were obtained. High shrinkage on firing caused excessive cracking, but the bricks were extremely dense and did not disintegrate until after four to six months. Unfired tar-bonded brick were made with sufficient strength to stand shipping and with a storage life of about four months. Fired tar-bonded brick showed less shrinkage and cracking than similar brick made with water. If dipped in tar to protect them from moisture, such brick will last five or six months before disintegration. It is possible, then to make dolomite brick with a storage life long enough to allow shipping and placing in furnaces. Stability, shrinkage and porosity of calcined magnesite; effect of flux and temperature of burning .—Unlike dolomite, magnesite showed less slacking effect the higher the temperature of burning. Roll scale gave greater stability than iron ore, probably because of its lower silica content. The product was comparatively porous and with low shrinkage, even with high proportions of roll scale.     

Multi-impregnating pitch-bonded Egyptian dolomite refractory brick for application in ladle furnaces

A method of preparation of multi-impregnated pitch-bonded Egyptian dolomite refractory brick for ladle furnace is described. Brick samples were prepared from blend of calcined dolomite mineral and coal tar pitch. The blend was hot mixed and pressed under a compression force up to 151 MPa. Green bricks were baked for 2 h at temperatures up to 1000 °C. Voids in the baked bodies were filled with carbon by multiple impregnations using low-softening point coal tar pitch. Each impregnation step (30 min) was followed by calcination at 1000 °C. Brick samples containing 8–12 wt.% coal tar pitch binder and pressed under 108–151 MPa acquired quantify crushing strength. However, multi-impregnating favored the mechanical strength of the baked brick samples and improved their hydration resistance (>45 days). Dolomite brick samples containing 10 wt.% coal tar pitch and pressed at 108 MPa gave high hydration resistance (more than 60 days in normal condition) compared to the hydration resistance of the commercial bricks (30 days). The prepared brick samples have acceptable density, chemical stability, outstanding resistance and good mechanical properties would meet the requirements of Ladle furnace (LF) for steel making industry. In addition, estimation of production cost of the brick indicates it is competitive with the market price based on durability and service life time aspects.