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。     

铝铬砖和镁铬砖抗艾萨炉炉渣蚀损的模拟研究

采用回转抗渣法模拟研究了试验温度、保温时间和熔渣加入量等因素对铝铬砖和镁铬砖抗艾萨炉炉渣侵蚀能力的影响。用SEM、EDAX及XRD等方法,对抗渣试样的显微结构和矿物组成进行了分析研究。结果表明:随着侵蚀温度的升高、保温时间的延长及炉渣加入量的增加,铝铬砖和镁铬砖的侵蚀面积增大;熔渣渗入铝铬砖后,形成铁铝尖晶石和铁铬尖晶石保护层,阻止了熔渣的侵蚀;三种耐火材料抗艾萨炉炉渣侵蚀能力由强到弱为:铝铬砖>电熔再结合镁铬砖>直接结合镁铬砖。     

Chemical corrosion mechanisms of magnesia–chromite and chrome-free refractory bricks by copper metal and anode slag

The penetration and corrosion resistance to copper and anode slag of six magnesia–chromite and six chrome-free refractory brick types were tested using static finger tests at a typical copper-refining temperature (1300 °C). The microstructures of the as-delivered and tested refractory types were investigated by means of electron-probe micro-analysis (EPMA) and scanning electron microscopy (SEM) techniques. The results showed that the overall wear rate of the fingers was very low, with the exception of the alumina-based brick made of fused corundum and magnesia–alumina spinel, and the magnesia-based brick made of sintered magnesia and zircon addition. In all refractory types new phases were formed as a result of slag-refractory interactions. Apart from the samples recovered from the copper zone of the latest generation of direct-bonded magnesia–chromite bricks, all the rest were completely infiltrated by copper and slag components (copper oxide, iron oxide, alumina and silica). However, the amount of infiltrated liquid in the chrome-free types was higher than in the magnesia–chromite bricks. Explanations are provided for the distinct infiltration behaviour. The results show that economically viable chrome-free refractory alternatives are still elusive for anode furnace linings.     

Kinetics of the formation of protective slag layers on MgO–MgAl2O4–C ladle bricks determined in laboratory

Carbon-bonded magnesia and magnesia-alumina bricks are the state of the art lining materials of the sidewalls and the bottom of steel ladles. Industrial trial tests revealed, that a new generation of MgO–MgAl₂O₄–C bricks, where pre-reacted spinel is added in form of a new calcium magnesium aluminate (CMA) raw material, exhibit a longer service life caused by an enhanced corrosion resistance due to the formation of a protective slag layer. In terms of this work, laboratory corrosion tests have been performed in order to mimic the protective slag layer formation and to study the kinetics of the formation. It has been found that the formation highly depends on the amount of iron present in the melt, which leads to the precipitation of the brownmillerite-phase. Furthermore, the study was extended to force the formation of protective slag layers of different composition which are reliable at higher temperatures and wider temperature ranges by targeted adaption of the brick composition. Cup tests showed that there is a potential to manipulate the composition of a protective slag layer by targeted adaption of the brick composition. Especially MgO, Al₂O₃, Fe_xO_y, and SiO₂ from the brick or slag enrich at the slag/refractory-interface.     

Properties of MgO–Fe–C refractories as linings of vanadium-extraction converter

For the purpose to extend the service life of MgO–C bricks used as linings of vanadium-extraction converters, MgO–Fe–C bricks with different carbon content were designed and the properties of this novel refractory were investigated by comparing to the traditional MgO–C bricks. The results showed that the poor service life of MgO–C bricks was due to the poor sinterability of the oxidized layer at 1400 °C, whereas the oxidized layer of MgO–Fe–C brick was well sintered due to the oxidation of Fe particles in the oxidized layer and formation of MgO–FeO_ss in air atmosphere. Excellent oxidation resistance and corrosion resistance against vanadium containing slag were also obtained due to the increase of compactness of oxidized layer and concentration of FeO in the oxidized layer compared to MgO–C bricks, and it is considered that MgO–Fe–C brick is a favorable substitute of MgO–C refractory to be used as linings of vanadium-extraction converters.     

4喷嘴对置式气化炉耐火砖蚀损影响因素浅析

简述了4喷嘴对置式气化炉耐火砖的结构形式和蚀损情况;分析介绍了其使用寿命短的影响因素及相应的技改措施：①气化炉烧嘴空间偏小,应增加气化炉长径比;②烧嘴物料喷入速度偏高,应控制其喷入速度;③拱顶耐火砖预制块结构不合理,则应改造其结构;④熔渣侵蚀,则砖壁应保留一定量的固态渣;⑤热应力破坏,则应保持稳定操作。结果表明：技改后气化炉拱顶砖的使用寿命由最初的780h提高到超过4300h。     

镁锆砖和镁铬砖的抗RH炉渣侵蚀性对比

为取代RH炉用镁铬材料,以电熔镁砂为主原料,分别加入单斜锆、脱硅锆、单斜锆与脱硅锆的混合粉、锆英石制备了ZrO2质量分数分别为15%和20%的镁锆砖,并利用静态坩埚法对比研究了镁锆砖和镁铬砖的抗RH炉渣侵蚀性。结果表明:对于Al2O3含量高且碱度(CaO/SiO2比)大的RH炉渣,镁锆砖抗侵蚀性能优于镁铬砖的;镁锆砖的侵蚀机理是砖中的ZrO2与渣中的CaO迅速反应,形成高熔点物相CaZrO3,能堵塞砖中的孔隙而形成致密保护层,从而阻止钢渣对镁锆砖的进一步侵蚀;而镁铬砖的侵蚀机理是渣中的Al2O3、Fe2O3等R3 和镁铬尖晶石中Cr3 交换,渣与砖反应生成的镁铝尖晶石和镁铁尖晶石使得材料变性,同时由于体积效应使镁铬材料鼓胀开裂,从而导致镁铬砖的严重侵蚀。     

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.     

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。     

水煤浆加压气化炉耐火砖渣蚀机理浅析

通过对使用后的耐火砖残砖取样分析,了解高铬砖显微结构和成分变化,找出气化炉内不同高铬砖受熔渣侵蚀损毁的机理。结果表明：对于结构相同的耐火砖,熔渣成分、温度和耐火砖的内部致密程度及杂质含量是影响耐火砖渣蚀速率的主要因素。     

烘炉常见问题及注意事项

烘炉的四大因素是负压、液化气流量、风门开度和气化炉液位,烘炉的效果直接影响投料时间和耐火砖的使用寿命。围绕这四大因素,对烘炉时出现的负压波动、渣口堵塞、无负压、开工抽引器放空处冒浓烟等故障进行分析和排查,为气化炉的稳定运行提供有利条件。     

澳斯麦特铜熔炼炉渣线用后铝铬残砖的分析

对澳斯麦特铜熔炼炉渣线部位使用后的铝铬砖进行了XRD、SEM和EDS分析。结果表明:在使用过程中,铝铬砖中的Al2O3、Cr2O3与渗入熔渣中的FeO反应生成高熔点的铁铝尖晶石和铁铬尖晶石,从而阻止炉渣对耐火材料的进一步侵蚀,延长炉衬的使用寿命;炉渣中的SiO2和CaO主要与砖中的Al2O3反应生成低熔点的硅酸盐相Ca(Al2Si2O8)。     

Slag Resistance of Magnesite-chrome Brick Impregnated with Chrome-bearing Sols

Cr2O3 has eminent slag corrosion resistance.So,the magnesite-chrome brick is thought as an important refractory material used in RH refining furnace in the process of steel-making around the world.After chromebearing sots being prepared by sol-gel method,single sol (Cr(OH)3)and mixed sol(Mg(OH)2-Cr(OH)3)were impregnated into magnesite-chrome bricks by vacuum impregnation.The corrosion resistance of the impregnated bricks to silicon steel slag was studied by porosimetric analysis and fiactal dimension calculation.The results showed that the corrosion resistance of impregnated magnesite-chrome brick was better than that of the unimpregnated brick and the brick impregnated by MgSO4 solution,and the one which has surface-treated by Mg(OH)2-Cr(OH)3 sol was the best,mainly because of lower apparent porosity,smaller pores diameter and their smoother inner suoface.     

铝镁尖晶石炭砖在盛钢桶上的应用

以铝镁尖晶石炭砖取代铝镁不烧砖在首钢第三炼钢厂９０ｔ盛钢桶上应用时效果良好．其侵蚀速率低，工作面反应层与变质层很薄，有较好的抗热震性能，尤其对抵抗碱性熔渣的侵蚀和渗透明显优于铝镁不烧砖。试验结果表明铝镁尖晶石炭砖的使用寿命比原用铝镁不烧砖提高一倍以上。     

Post-mortem analysis of MgO–Al2O3–C bricks containing bauxite used in steel ladle walls

A serious problem with integrated masonry linings ladle was that the ladle wall bricks were difficult to be partially replaced. Thus, the service life of the ladle was determined by the properties of ladle wall bricks. In this study, the new generation of MgO–Al₂O₃–C bricks with bauxite aggregates was tested in a ladle lining of an integrated steel ladle for 103 cycles, and the corroded microstructure of the used brick was investigated. A multilayered structure of bauxite aggregates could be observed in the used brick, which inhibited the slag penetration along the boundary of the magnesia aggregates and reduced the degree of the aggregates fall off from the used bricks. Besides, during the process of slag penetration, bauxite aggregates could melt into the slag, which increased the viscosity of the slag and weakened the penetration ability of the slag. The MgO–Al₂O₃–C bricks with bauxite addition could improve the service life of the ladle to a certain extent.     

Corrosion mechanism of MgO-C bricks used as linings in a vanadium extraction converter

To extend the service life of MgO-C bricks used as linings in vanadium extraction converters, their corrosion mechanism was investigated using stationary immersion and rotary crucible methods at 1673 K. The effects of oxides in vanadium slag were studied using the slag invasion method. The results showed that a decarburization layer was formed but was not effectively sintered under vanadium extraction conditions, resulting in it having a loose structure and poor binding strength. When slag-splashing technology was applied to protect the converter, the decarburization layer and slag-splashing layer easily fell off due to scouring by the molten pool. Consequently, the poor strength of the decarburization layer was the main reason for the poor anti-erosion performance of the MgO-C bricks and the weak effect of slag-splashing technology. In addition, higher contents of SiO₂ and TiO₂ in vanadium slag could form low melting point compounds and increase the thickness of the decarburization layer, thereby accelerating the MgO-C brick corrosion rate. Higher contents of FeO in the vanadium slag not only formed low melting point compounds but also caused a decarburization reaction with the MgO-C bricks. However, with increases of V₂O₃ in the slag, the formation of high melting point compounds decreased the corrosion rate and corrosion depths.     

Performance of a ceramic frit anti-oxidation coating on a MgO-C refractory brick

In steel production, ladles must be preheated to minimize the heat loss of the steel melt, prevent thermal shock of refractory bricks (MgO-C), and to maximize the lining life of ladle. Partial oxidation of MgO-C bricks begins in the graphite bond during the preheating. Oxidation of graphite bond also causes a decrease in performance of the bricks because of an increase in the brick porosity. In this article, coating on a MgO-C brick surface by a ceramic film to protect against carbon oxidation was studied. Coated and un-coated bricks were heated at 1200 °C, cooled to room temperature, then the brick properties investigated. The oxidization resistance properties of brick with coating were much better than those without coating, which should lead to longer refractory service life.     

Corrosion behavior of carbon,Al2O3, and MgO refractories during the preparation of a Ti–Si–Al alloy via the aluminothermic reduction of a Ti-bearing blast-furnace slag

The extraction of Ti from Ti-bearing blast-furnace slag (TBFS) via aluminothermic reduction to prepare Ti–Si–Al alloy has several promising applications. However, the refractories of the furnace lining can dissolve into the molten slag and change the composition of the slag, not only shortening the life of the refractories, but also influencing the preparation of Ti–Si–Al alloys for industrial applications. The main purpose of this study was to explore the corrosion behavior of refractories (carbon, alumina, and magnesia bricks) and determine the most suitable refractories for the aluminothermic reduction of TBFS. Herein, for the first time, the dissolution equilibrium of refractories during the aluminothermic reduction of TBFS and its effect on aluminothermic reduction were revealed. The results revealed that the alumina and magnesia bricks were more effective for obtaining bulk Ti–Si–Al alloy and avoiding high mass loss of the Ti–Si–Al alloy compared to the carbon bricks. Furthermore, the corrosion of alumina and magnesia bricks increased with an increase in the content of the added CaO; however, the corrosion of the alumina bricks was more severe compared to the magnesia bricks. In addition, the largest extraction ratio of Ti (maximum value: 99.85%) was achieved when magnesia bricks were employed. The results of this study indicate that magnesia bricks are the optimal refractory for the preparation of Ti–Si–Al alloy via the aluminothermic reduction of TBFS. This work provides important experimental information for the industrial application of the aluminothermic reduction of TBFS in the preparation of Ti–Si–Al alloys.     

Service Results and Analysis of Fully Co—clinkered Magnesite—Chrome Brick in Slagline Area of VOD Vessel

Operating condition and service results of several tested bricks in slagline area of the VOD vessel are described,It has been shown that the fully co-clinkered magnesite chrome brikc is superior,followed by two-stage calcined magnesite-dolominte brick,preracted magnesite-chrome brick and one-stage calcined moagnesite-dolomite brick. Chemical and petrologial examination were carried out by conventional analysis and optical microscope respectively,The reason of damage of the tested bricks are discussed and described as follows:(1) MgO in brick is erosed and dissolved by slag to destroy structure of the direct bond;(2)slag penctrating into the brick and then reacting with it to from various belts leading to spalling;(3)reducing action of reucing agents;(4) vaporiztion of some composition in the brick at high temperature under vacuum causes reducing weight and increasing porosity and (5) serious machanic abrasion.Therefore,Some opinions on increasing lining life of VOD vessels are suggested.     

7.63m焦炉主要耐火材料简评

介绍了7.63m焦炉主要耐火材料的品种、数量、材质及各种砖型的验收技术条件,同时还对半硅砖、硅线石砖、硅火泥、格子砖等的应用问题进行了深入的讨论.7.63m焦炉炉体密封性好,但异型砖多,有些砖的成品率极低,复杂的炉体结构对焦炉生产操作和寿命是否有影响还需进一步的实践验证.