Development and Application of High-Performance Magnesia-Chrome Bricks for RH Degasser

The paper analyses the wear mechanism of magnesiachrome bricks for snorkel of RH degasser.High-performance magnesia-chrome bricks with good resistance to molten slag and infiltration resistance have been manufactured by means of reasonable fabricating technology.The application results of the developed magnesia-chrome bricks at 300t RH degasser of Baosteel indicate that the lining life has been increased up to 150 heats.     

Formation of ferrospinel layer at the corroded interface between Al2O3-spinel refractory and molten steel in RH refining ladle

Refining ladle is generally the last inclusion-removal vessel before the continuous casting of steel, so, it has a vital effect on the final steel quality. In this work, degradation process of a cement-free Al₂O₃-MgAl₂O₄ refractory in contact with molten steel/slag in the metal bath area of a Ruhrstahl Heraeus (RH) refining ladle was investigated. A reaction product layer with the formation of ferrospinel (hercynite) and Fe-rich phases was observed, suggesting that the interactions/reactions between the refractory lining and the molten steel should also be considered to have a better understanding of overall degradation mechanism of the refractory served under the RH refining conditions. The two types of alumina grains in the refractory, sintered and fused alumina, were attacked in an active way and a passive way, respectively. The effect of the crack generation and steel infiltration on degradation of the refractory was also discussed in detail, based on the microstructural characterizations.     

RH精炼装置流场对混合、脱碳、夹杂物行为的影响

基于计算流体力学、反应热力学及动力学,对RH气液流场、脱碳及夹杂物碰撞长大进行了数值模拟. 结果表明,在提升气量为400 NL/min条件下,气泡在上升管存在贴壁效应;1000 NL/min下,侧吹气体可形成吹透现象;RH脱碳处理中,0~3 s的脱碳速率为45~70 mol/s,3~500 s时降低到5 mol/s,500 s后脱碳速率进一步降低;经过14 min处理后夹杂物质量浓度可降低到5′10-5以下;数值模拟结果与实验测量结果符合良好,说明数值模拟方法可完全用于RH真空精炼过程中关键工艺参数的预测.     

RH真空精炼过程数值模拟的研究现状及展望

近年来,RH真空精炼已成为重要的二次精炼工艺之一,相应的数值模拟工作受到许多研究者的关注.目前涉及到RH精炼过程的数值模拟研究主要集中于以下几个方面:RH精炼装置内气液两相流动行为的数值模拟,脱碳和脱气过程的数值模拟以及夹杂物碰撞长大行为的数值模拟.本文综述了RH精炼过程数值模拟的研究现状,并提出了应重点解决的问题.     

Wear mechanism of a novel AlSiMgAl2O4Al2O3 composite used in the low vessel of an RH secondary refining furnace

A novel AlSiMgAl₂O₄Al₂O₃ composite brick was prepared and evaluated in the low vessel of an RH (the initials of Ruhrstahl and Hereaeus) secondary refining furnace; it was characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The results show that after use, the AlSiMgAl₂O₄Al₂O₃ composite has a functional gradient with an erosion zone–reinforced zone–original zone phase distribution, in which the phases in the erosion zone (0–1.8?cm) are a Mg-hercynite spinel solid solution, α-Al₂O₃, and minor amount of Al₃Fe₅O₁₂. Furthermore, the phases in the reinforced zone (1.8–5.0?cm) are γ-AlON, 21RSiAlON, SiC, Mg_0.388Al_2.408O₄, and α-Al₂O₃; i.e., the Al and Si in the composite are completely converted into non-oxide reinforced phases. Finally, the phases in the original zone (>5.0?cm) show no change. The reaction mechanism is as follows. During operation, a Mg-hercynite spinel solid solution is formed in the erosion zone due to a reaction between MgAl₂O₄ and FeO from a refinery operation. Therefore, the slag erosion of the material is improved. The Al and Si metals undergo active oxidation, and 21RSiAlON flakes are subsequently formed from the products of the metastable Al₂O(g), SiO(g), and N₂(g) in the ambient. The γ-AlON is formed by a carbothermal reduction nitridation of the α-Al₂O₃ and residual active carbon from the resin binder. The 21RSiAlON and γ-AlON reinforce the composite brick and improve its high temperature performance accordingly. Its service life is 110% that of the magnesia-chrome bricks used in the same period. The reaction model was also established.     

RH真空炉衬用无铬耐火材料抗渣性能的研究

对镁锆质、镁尖晶石质、镁尖晶石钛质和镁尖晶石锆质4种典型的无铬耐火材料的抗渣侵蚀性能进行了研究,并与RH真空炉下部槽用镁铬砖进行了对比。结果表明:炉渣对耐火材料的侵蚀主要是通过炉渣中铁氧化物、CaO、SiO2和MnO向材料内部扩散而产生的侵蚀反应造成的。镁锆质材料中的ZrO2吸收炉渣中的CaO生成高耐火性能的CaO.ZrO,使镁锆材料较其他3种MgO基无铬耐火材料具有更优良的抗炉渣侵蚀性。     

镁合金无铬化学转化膜的研究进展

随着人们环保意识的提高,开发无毒无污染的镁合金无铬转化膜也越来越得到重视.较详细地综述了镁合金无铬化学转化膜的发展现状,主要介绍了磷酸盐转化膜、磷酸盐,高锰酸盐转化膜、锡酸盐转化膜、钼酸盐转化膜、稀土转化膜等工艺,对膜层的耐蚀性、耐磨性等进行了比较,提出镁合金无铬化学转化膜是今后研究的热点.     

Composition of Ladle Slag and Refractory Materials and Its Effect on the Wear Resistance of the Lining of an RH Vacuum Degasser

The resistance of magnesian spinellide refractories to molten slag attack is studied and effects associated with the material composition and the microstructure of test specimens are discussed. The mechanisms of corrosion wear and chemical reactions involved are considered in detail. Slags with a basicity of 1.9 – 2.1 react with periclase to yield spinel, calcium orthosilicate, and monticellite. To prevent the chemical corrosion of periclase, sintered periclase or alumina as additions to the slag are recommended for use. __________ Translated from Novye Ogneupory, No. 3, pp. 33 – 36, March, 2005.     

RH插入管用优质镁铬砖的开发

以国产优质菱镁矿和铬精矿为主要原料，采用电熔和烧结预合成料并用工艺，研究了不同添加剂对优质镁铬砖性能的影响。结果表明，添加剂可富化方镁石固溶体的晶内尖晶石，促进晶间尖晶石的形成，赋予制品高强度和优良的抗渣性；电熔和烧结料并用工艺．可控制显微结构，改善其抗热震性。本制品在引进RH和RH－OB炉括入管上使用，侵损速度和使用寿命均优于引进同类产品。     

RH真空处理装置的应用

从工艺装备,控制系统组成以及真空处理的效果等方面,介绍了安钢第二炼轧厂170tRH真空处理装置的应用。     

Development and Markets of China‘s Refractory Raw Materials

The distribution of refractory raw material resources,its throughput capacity, product varieties and quality as well as market situation in China were investigated.     

Simultaneous Determination of Thermal Conductivity and Specific Heat for Refractory Materials

The present work describes a transient method for determining thermal properties of refractory materials. Specific to this technique are (1) the experimental measurement of heat flux on the heated surface and (2) a method of data analysis based on the numerical techniques of nonlinear least squares and finite difference. Several mathematical formulations are proposed to minimize computing time requirements. Silica molding sand is used in two examples to illustrate the applicability of the technique to refractory materials. Owing to the measurement of heat flux on the heated surface, both thermal conductivity k and volumetric specific heat C can be determined if their temperature dependencies are not considered. In the case when temperature-dependent thermal properties are considered, it is found that the inherent accuracy of the experiment does not allow the determination of both temperature-variable k and C at the same time. It is shown that the present method has advantages in the ease and directness of the required experiment and in greater computational efficiency. Thermal properties are reported for a bonded silica and an unbonded silica sand.     

端羧基超支化聚合物-铝无铬鞣剂的制备及应用

根据超支化聚合物官能团度大,反应活性高的特点,利用端羧基超支化聚合物(HPAE-C)的末端羧基与Al3+络合,制备一种新型的无铬鞣剂(HPC-Al),通过单因素实验考察了反应条件对成革收缩温度的影响,确定了最佳合成条件:m(HPAE-C)∶m〔Al2(SO4)3〕=2∶1,反应温度30℃,pH=3,反应时间3 h。采用IR、XRD对产品分子结构进行表征,并采用热重分析仪测试了产品的热性能,HPC-Al的热分解温度为243℃。将产品应用于皮革鞣制中,其单独鞣革收缩温度为76.6℃,铬复鞣后收缩温度大于95℃,且物理力学性能明显提高。     

Thermochemical Treatment--Technologies for Recovery and Utilisation of Materials

The arc furnace technology is an ideally suited process for the treatment of hazardous and problematic waste. The operation conditions of the arc furnace can be adapted for optimal transformation of the waste material input into raw materials and usable products. The process can significantly reduce the impact of contaminated wastes and industrial residues, and enable material conversion and separation. Thus, the products of the process have various applications. The capability of the process is illustrated with three examples, the treatment of bottom ash and filter ash from waste incineration plants, of stainless steel slags and of chromium containing residues from the refractory industry.     

RH炉浸渍管外衬刚玉-尖晶石浇注料的研制

通过选择合适的超细粉加入量、镁砂粒度组成及加入量,优化基质的组成,利用A1     

Development and Application of Refractory Materials for Molten Aluminum Applications

Two new refractory materials have been developed for use in molten aluminum contact applications that exhibit improved corrosion and wear resistance leading to improved thermal management through reduced heat losses caused by refractory thinning and wastage. The development of these materials was based on an understanding of the corrosion and wear mechanisms associated with currently used aluminum contact refractories through physical, chemical, and mechanical characterization and analysis performed by Oak Ridge National Laboratory (ORNL) and the University of Missouri, Rolla Rolla (UMR), along with their industrial partners, under the ITP Materials project "Multifunctional Metallic and Refractory Materials for Energy Efficient Handling of Molten Metals." Spent castable refractories obtained from a natural gas-fired reverberatory aluminum alloy melting furnace were analyzed, leading to identification of several refractory degradation mechanisms and strategies to produce improved materials. The newly developed materials have been validated through an R&D industrial trial.     

镁钙系耐火材料的发展研究

介绍了一种被广泛使用的镁钙系耐火材料的特性,发展现状和制造工艺. 并针对镁钙系耐火材料游离CaO的防水化问题提出了一些措施.     

Transient Hot-Strip Method for Simultaneous Determination of Thermal Conductivity and Thermal Diffusivity of Refractory Materials

The transient hot-strip method has been used for determining thermal conductivity and thermal diffusivity of a refractory brick. The technique is based on recording the transient temperature increase of a 25-μm-thick, 8-mm-wide, and 70-mm-long iron strip clamped between two sample halves and heated with a constant direct current. The method is accurate to within 5% in the thermal conductivity and to within 10% in the thermal diffusivity in the temperature range 20° to 700°C.     

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.