高铬耐火材料在熔渣气化炉中的剥落模式

在熔渣气化炉中,将煤转化成可燃烧洁净能源的可行性一直受到气化炉热面耐火材料使用寿命的制约。影响耐火材料使用寿命的最主要损毁机制是材料的剥落,无论是材料体积膨胀(受到压应力)或是体积收缩(受到拉应力)时都会产生剥落。对于高铬耐火材料的性能以及使用特性而言,在气化炉操作环境下,体积收缩是其损毁的基础模式。这种模式在适当情况下可以预测气化炉用耐火材料的使用寿命,如铬挥发并向表面扩散,熔渣从气孔和裂纹向材料内部渗透。     

钢包渣向铝尖晶石质钢包衬的渗透

1.前言 钢包内衬用耐火材料由于采用浇注施工方法,可实现低成本化和大幅度省力化。当前浇注料是以铝尖晶石质材料为主体。该材质的损毁状况是以随着熔渣的渗透而产生的变质层的剥落为主。因此,为了抑制熔渣的渗透,进而提高其耐用性的改进正在各个公司进行。本文介绍了对实际使用的浇注料的溶渣渗透状况进行的调查和今后改进方向的研究情况。     

熔渣与耐火材料高温润湿研究进展

熔渣的侵蚀是导致耐火材料损毁的主要原因之一，主要表现形式是耐火材料在渣中的熔解及熔渣向耐火材料中的渗透，这2个方面都与熔渣在高温下与耐火材料的润湿性有关，耐火材料的高温润湿性能可以通过熔渣在其表面的张力、黏附功和铺展系数等参数加以表征。改变耐火材料的组成及粗糙度等可以降低熔渣在耐火材料表面的润湿，进而提高耐火材料的服役寿命。本文从熔渣组成、耐火材料组成及表面微观效应等方面综述了耐火材料表面熔渣高温润湿性的影响因素，同时也展望了该领域未来研究发展方向。     

熔炼Fe-Si-B合金的中频感应炉用石英捣打炉衬的损毁机制

以天然石英和熔融石英为原料,加入硼酐捣打成熔炼Fe-Si-B合金的无芯感应炉衬,研究了该石英质炉衬的损毁机制。结果表明:炉衬服役后烧结层会产生含Fe氧化物的渗透层;渗透层中Fe的氧化物会与SiO_2反应使炉衬原有网状结构遭到破坏,同时还会伴随体积效应加大内部应力使裂纹扩展,造成烧结层强度进一步降低;炉衬下部损毁严重与烧结层强度降低及电磁搅拌引起的合金液对炉衬冲蚀和磨损有关; 1 350～1 380℃下,Fe-Si-B合金熔体中Al会与SiO_2反应侵蚀炉衬,但侵蚀程度有限。     

攀钢RH炉用耐火材料的现状、损毁机理和发展

介绍了攀钢RH真空处理系统所使用主要耐火材料的现状,分别从熔渣侵蚀、热应力以及机械应力方面分析了损毁机理,从耐火材料方面和炼钢操作方面提出了长寿化的建议,并结合攀钢实际情况,提出了两方面的发展建议。     

电炉耐火材料衬的管理

电炉炼钢的新技术已影响到耐火材料的性能,耐火材料机械损毁机理仍然相同,但是炉衬的性能已得到提高,并且随着耐火材料炉衬管理方案对新设备和工艺技术的影响,使耐火材料的成本有所降低。     

RH精炼炉用耐火材料及提高其寿命的途径

较系统地介绍、论述了以下内容:1)RH真空脱气精炼炉类型;2)RH精炼条件及侵蚀严重部位;3)造成一些部位侵蚀严重的原因分析,包括:高速循环流动钢液的冲刷,温度波动造成的热剥落与结构剥落,真空对镁铬砖的损害,铁硅酸性渣及脱硫粉剂对真空室下部、底部与喉口炉衬的侵蚀,浸渍管耐火衬最易蚀损的原因;4)用旋转圆柱体法、回转圆筒法及相图研究分析的结果,抑制熔渣渗入耐火材料,减轻结构剥落的途径;5)适合RH炉不同部位用的耐火材质与维修喷补料的研究、开发情况;6)RH炉精炼硅钢的过程与炉衬用耐火材料;7)提高RH炉炉衬寿命的途径.     

熔渣气化炉用添加磷酸盐的高铬耐火材料损毁机理

气化炉是一个反应容器,将含碳原料(如煤和石油焦)在高温高压的还原气氛中(极低的氧分压)与氧气反应生成CO和H2的合成气。这种合成气被用作化学生产中的原料或者是用来发电。气化过程的副产品包括:1)未反应的碳;2)CO2和H2S等热气;3)含碳原料在气化炉液化过程中形成的矿物杂质或是有机金属复合物共同形成的熔渣。在气化炉中,熔渣与高铬耐火材料衬里之间发生反应会导致两种主要的剥落(结构剥落和化学剥落)和化学熔蚀。在高铬砖中添加磷酸盐相是最近研究出来的,能够起到减缓耐火衬里剥落和减轻熔渣对耐火材料衬里的化学熔蚀。本文讨论了磷酸盐相对砖的显微结构影响并降低由于熔渣侵蚀所造成的耐火材料损毁。     

水泥窑耐火砖机械损毁机理分析及应对措施

随着水泥窑煅烧温度的提高,窑速的加快,机械应力一直是耐火材料损毁的重要因素。机械应力损毁主要表现形式为窑筒体椭圆度、砖衬错位、沟槽和挡砖圈挤压等。根据耐火砖不同损毁情况分析其损毁原因及机理,并针对性提出修正方案,有利于改善耐火材料使用效果,延长使用寿命,也为水泥生产达到节能降耗、节约成本的目的。     

水煤浆加压气化炉用高铬耐火材料的显微结构及损毁机理

采用扫描电镜和能谱分析方法 ,分析了水煤浆加压气化炉用高铬砖渣蚀前后的显微结构和相组成 ,探讨了主要损毁机理。结果表明 :煤熔渣与砖反应和渗透引起砖组成的改变 ,从而导致砖的结构剥落和强度弱化是砖损毁的主要原因 ;LIRR -HK90砖的显微结构呈网络状镶嵌结构 ,直接结合程度高 ,与渣反应可生成 (Mg ,Fe) (Al,Cr,Fe) 2 O4 复合尖晶石致密带 ,阻止了渣的进一步渗透 ,减缓渣蚀速度和结构剥落 ,其使用效果优于进口的同类产品     

Spalling degradation of Cr2O3-Al2O3-ZrO2 refractories for coal-water slurry gasifier linings: Role of phosphate

Two kinds of high chromia bricks with and without phosphate as gasifier linings were postmortem analyzed during their whole service life. The effect of phosphate on the microstructure and phase composition of refractory sections was analyzed. The dense phosphate enrichment layer was observed between the slag penetration layer and the virgin layer, which was considered to reduce the damage of gasifier lining caused by spalling. Phosphate could decompose and migrate slowly under suitable temperature gradient existing in the bricks in service, which would result in the densification of the microstructure earlier than slag penetration. The phosphate in high chromia bricks reduced frequency of spalling due to penetration, which would lead to the lower early wear rate and longer lifetime.     

Application Study onβ—Sialon—Al2O3 Brick in Iron Ladle

The microstructure and slag erosion fractal dimension of reaction interface of β-Sialon-Al2O3 brick used in 300 Mt iron ladle of Baosteel have been studied by SEM and XRD.The results indicated that β-Sialon-Al2O3 brick exhibited excellent slag resistance.The main wear mechanism of β-Sialon-Al2O3 brick is mainly from the spalling caused by thermal mechanical stress and attacked by slag secondly.     

300t精炼钢包温度场和应力场的有限元分析

在目前所用材质体系和砌筑结构的基础上,对精炼过程中的300 t精炼钢包剪切应力场、温度场和热应力场以及膨胀缝的最大接触应力进行了有限元研究.结果表明:在LF精炼过程中,渣线处的内衬砖最容易受冲刷和热应力的作用而损毁,需在保证良好抗渣性能的同时采用热膨胀系数低、抗冲刷性好的耐火内衬砖;膨胀缝的最大接触应力与膨胀缝的大小呈线性反比关系,以保持在0.8～1.8 mm之间为宜.     

Role of Calcium Magnesium Aluminate in Carbon-containing Bricks for Steel Ladle

Calcium magnesium aluminate,with the commercial name of MagArmour,is a synthetic material consisting of 70 mass%Al₂O₃,20 mass%MgO and 10 mass%CaO,approximately.It is characterized by porous microstructure,intergranular aluminates phases and micro-crystalline spinel.Since globally launched in 2017,MagArmour has been successfully applied to various carbon-containing refractories serving for steel refining process.Lots of cases have demonstrated the role of MagArmour in enhancing the service life of carbon containing bricks for ladle lining.The benefits embody in formation of protective coating on hot surface,relief of drilling corrosion in joint positions,and elimination of grooves or cracks caused by mechanical stress concentration.In addition,MagArmour is effective in protecting graphite from deep oxidization so as to be capable of replacing the metallic or carbide anti-oxidants in carbon-containing bricks entirely.By means of chemical analysis and microstructural dissection,postmortem investigations on the used MgO-C bricks from both metal and slag zones of 120t steel refining ladle were conducted to clarify the working mechanism of MagArmour.The formation of protective coating on hot face is attributed to the dissolution of micro-crystalline spinel into contacting slag,which changes the slag chemistry so as to enhance viscosity.The improvement in corrosion/erosion resistance is highly related to the porous microstructure and dispersive aluminates.As well known,evaporation of Mg,Al and SiO,and/or internal migration,occurs in MgO-C bricks at elevated temperatures.The gaseous phases are absorbed by MagArmour particles due to the high surface area of porous microstructure and condense as corresponding oxides.These oxides react with the intergranular calcium aluminates forming liquid phase.With increasing temperature,the liquid phase seeps into the matrix under capillary force.The increased liquid amount improves the flexibility of the matrix and thus releases the internal stresses concentration resulting from mechanical stress and temperature gradient.Meanwhile,densification of the matrix microstructure occurs under the static pressure generated by liquid steel and molten slag,which blocks the channels of oxygen infiltration.     

中间包镁质干式振动料蚀损机理研究

采用相图分析了中间包溶渣对于式振动料的侵蚀机理,并用扫描电镜、能谱及X-ray衍射对中间包干式振动料残衬进行显微观察和分析.结果表明:在中间包使用初期,熔渣对中间包工作衬侵蚀的途径为渗透;在渗透的同时,熔渣对干式料产生化学侵蚀及干式料对熔渣产生化学过滤作用、方镁石溶于熔渣改变了熔渣的性质,提高了熔渣的熔点和粘度,在干式振动料/熔渣界面形成致密的结构,阻碍熔渣的进一步渗透;此后,熔渣对干式料侵蚀的主要途径是对界面致密层的溶蚀.     

旋风炉SiC质炉衬损毁机理研究

热电厂旋风炉ＳｉＣ炉衬，由于受液态渣的侵蚀，在短期内损毁。本文研究了液态渣的物相、渣村的相互关系，认为ＳｉＣ炉衬的侵蚀机理：一方面由于增钙，液态渣变稀，渣中多钙、铝而少硅，对炉衬的渗透力强，能夺取ＳｉＣ中的硅，造成化学侵蚀；另一方面是由于旋风燃烧的作用，液态渣对炉衬的机械侵蚀。该研究结果为研制新炉衬提供了依据。     

Structure and properties of lightweight magnesia refractory castables with porous matrix

To improve the energy-saving capacity of magnesia refractory castables for working lining of high-temperature kilns, this study presents the researches on microstructure and properties of lightweight magnesia refractory castables with porous matrix fabricated by direct foaming method. The results show that formation of closed-pores in the matrix significantly enhanced high-temperature thermal insulation performance of castables with minor changes of slag corrosion resistance. The thermal conductivity of the lightweight magnesia castables at 1000 °C was below 1.2 W/m·K, which is 47.8% lower than that of the referenced magnesia castable. The increasing content of SDS (foaming agent, over 0.02 wt%) led to increments of size and number of large-sized pores, resulting in the significantly decreased density and mechanical performances. The slag resistance mechanism reveals that, in addition to intergranular penetration, the accumulation of slag and penetration between adjacent pores were the major ways of slag mass transfer in lightweight magnesia castables. In conclusion, controlling the size (below 53.2 μm), number and distribution of closed-pores in the matrix is effective to realize the coupling of high thermal insulation, mechanical properties and slag resistance for lightweight magnesia castables used in the metallurgical field.     

Improvement of Service Life of Small Furnace Covers on 150 t Refining Ladles

The factors restricting the life of the refining furnace cover were introduced, including the airflow erosion of the refining dust removal system, the melting loss caused by the arc radiation of the electrode, the chemical erosion and penetration of slag and gas, and the condition of refining slag. The improvement measures are adjusting the material of the small furnace cover from corundum to chrome corundum, using a large shaking table to vibrate, optimizing the size design of the small furnace cover, and appropriately thickening the weak areas in the triangular area. The average service life of the refining furnace cover has been increased from one week to two months, reaching 4 maintenance cycles, which meets the needs of the refining production.     

钢包粘渣与包衬耐火材料

阐明了钢包粘渣与包衬耐火材料存在一定的关系 ,抗渣渗透性差、容易出现开裂的包衬耐火材料容易粘渣。为防止钢包粘渣 ,适于采用抗侵蚀性和抗渣渗透性优良的尖晶石砖、铝尖晶石 (或铝镁 )浇注料、低密度浇注料以及抗剥落性好的刚玉 -锆英石浇注料作包衬耐火材料     

A post-mortem analysis of the used gel-bonded Al2O3–MgAl2O4 castables in an industrial steelmaking ladle

In this work, a cement-free alumina-spinel (Al₂O₃–MgAl₂O₄) castables with a new aluminum–magnesium gel binder were developed to line the Ruhrstahl Heraeus refining ladle, chemical attacks, and degradation mechanisms of the used alumina-spinel castables after industrial trials were investigated. The results indicated that a reaction product layer of (Mg, Fe)Al₂O₄ was observed between the slag layer and penetration layer (PL), which was mainly derived from the reaction between MgAl₂O₄ spinel in the refractory matrix and FeO_t from slag or an oxidation of steel, and thereby prevented the further penetration of FeO_t. Meanwhile, the in situ spinel could also entrap slight CaO, SiO₂, and FeO_t from the infiltrated slag to form composite spinel in the PL. Moreover, chemical corrosion/penetration and structural spalling dominated the degradation process of the refractory lining in this case. Cracks formed between the deteriorated layer and original layer because of mechanical and thermal stress, which caused spalling from the refractory's hot face.