中间包用颗粒型镁质覆盖剂烧结性能的研究

主要研究了石墨和镁砂粉料配入量 ,以及钢包渣种类和加入量等对中间包颗粒型镁质覆盖剂烧结性的影响。结果表明 :覆盖剂颗粒内添加一定量的石墨 ,将促进覆盖剂颗粒间的烧结 ;在颗粒型镁质覆盖剂的成品颗粒中加入的粉料越多 ,越容易烧结 ;钢包渣对镁质覆盖剂的烧结有直接影响 ,加入量愈大 ,覆盖剂颗粒之间越容易烧结。     

中间包结构及包衬耐火材料对钢水清洁度的影响

通过中间包砌筑结构的变化,分析了钢水内不同级别的颗粒夹杂物上浮的机率;又通过中间包内渣层中示踪剂的变化,分析了包衬耐火材料在单炉钢水冲刷下的侵蚀量,从而定量判定了中间包结构及包衬耐火材料侵蚀对钢水清洁度的影响程度。     

Increasing wear resistance of stoppers for 140-ton steel-casting ladles

Conclusions Among the principal reasons for partial or substantial leaking of the metal stream are the following: burning away of the stopper, breaking off of the spherical part of the head, wear and tear of the head and sleeve bricks and opening up of the seams through deformation of the rod.The stoppers burn away on account of a great deal of wear and tear in the pipes, erosion of the seams, formation of cracks in the pipes and head and deformation of the stopper on account of the rod becoming too hot.The amount of slag in the ladle is one of the main factors for corrosion wear in stopper pipes. The aggressive action in the slag increases as the temperature of the metal and casting time are increased.Breaking off of the spherical part of the head during the first stopper opening due to the formation of skull between the stopper saddle and head can be avoided by using a graphite filling.Insulation of the stopper rod reduces the temperature during casting by 150–300°. The use of good quality mortar in assembling stoppers reduces the erosion of seams, while the use of a high-alumina putty prevents wear in the pipes.     

高炉用Si3N4结合的SiC质耐火材料的氧化

通过称重方法和表面显微结构的观察,较系统地研究了高炉用Si_3N_4结合的SiC质耐火材料在空气、水蒸汽和不同CO/CO_2比的混合气相中的氧化过程,探讨了该材料的氧化动力学。本文针对高炉冷却设备漏水情况而设计的水蒸汽氧化及其模拟高炉冶炼环境而设计的不同CO/CO_2比混合气相中的氧化实验结果,为研究高炉用Si_3N_4结合的SiC质耐火材料的蚀损过程提供了一定的理论依据。     

玄武岩熔液对耐火材料的侵蚀

为深入了解玄武岩高温熔体对耐火材料的侵蚀行为,参照ASTM C621—1984(2001)分别对致密氧化铬砖、致密锆英石砖和熔铸锆刚玉砖(AZS-33)进行了1 500℃72 h的玄武岩熔液侵蚀试验,并对侵蚀后试样进行了显微结构对比分析。侵蚀试验结果表明,致密氧化铬砖的抗熔融玄武岩侵蚀性最好,其次是致密锆英石砖,最差的是熔铸AZS-33砖,其在液面线处出现严重剥落现象。显微结构分析表明:致密氧化铬砖结构均匀,与玄武岩熔液反应性小,同时与玄武岩渣中的成分形成尖晶石致密层阻止了渣的进一步渗透;致密锆英石砖表面与玄武岩熔液反应产生很薄的脱锆层和玻璃相,并且其致密均匀的结构也阻止了渣的进一步渗透;熔铸锆刚玉砖的显气孔率虽然很低,对玄武岩熔液有较好的抗渗透性,但其液相量较多,因此抗侵蚀性相对较差。     

高温熔渣对水煤浆气化炉耐火砖的影响

对使用后的耐火砖残砖进行取样分析,以了解高铬砖显微结构和成分变化,找出水煤浆气化炉向火面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,在高温熔渣侵蚀耐火砖的过程中,主要影响因素是熔渣的成分、工作温度、耐火砖的致密度和杂质含量,熔渣中的SiO2含量是造成渣蚀的直接原因,而耐火砖的工作温度、致密度和杂质含量决定了渣蚀的速率。     

ZrO2-C质耐火材料抗侵蚀性的研究现状

由于ZrO2-C质耐火材料具有优异的抗侵蚀性,因此它被广泛应用于连铸用浸入式水口渣线部位以及塞棒的棒头部位。本文介绍了ZrO2-C质耐火材料的主要原料,阐述了ZrO2-C质耐火材料的蚀损机理以及改进抗侵蚀性的措施。     

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。     

连铸用复合式整体塞棒

整体塞棒的棒体部位以特级高铝熟料、电熔刚玉和鳞片状石墨为主原料；塞头部位以电熔刚玉、特级高铝熟料和鳞片状石墨、碳化硅为主原料。选用液体树脂为结合剂并加入适量的添加剂。该制品在８ｔ连铸中间包使用，可连浇８炉。     

连铸中间包定径水口快速更换与中间包长寿技术

介绍了连铸中间包定径水口快速更换与中间包长寿技术。两年多的生产应用结果表明 :1)采用该技术后 ,中间包寿命最高达 147炉 ,单中间包连拉时间大幅度提高 ,钢坯合格率提高 (敞开浇铸时为 99.99%,保护浇铸时为 99.98%) ,合格坯收得率也由过去的 98%以下提高到 99.75 %以上 ,劳动强度和生产用材料的单耗显著降低 ;2 )塞棒控制系统的取消 ,不仅降低了消耗 ,也消除了塞棒对钢水的污染 ;3)连铸起步次数的减少 ,使结晶器铜管和引锭杆的使用寿命提高了 2～ 3倍 ;4 ) 2 0 0 0年 ,莱钢炼钢厂采用保护浇铸条件下定径水口快速更换技术和中间包长寿技术 ,降低成本 2 4 0 0万元。     

A90尖晶石在熔融还原炉渣中的侵蚀行为

在弱还原气氛下，研究了一种富铝尖晶石Ａ９０在不同ＦｅＯ含量熔融还原炉渣中的侵蚀行为。借助于扫描电镜和ＥＤＡＸ技术对侵蚀后的试样进行了分析，结果表明：Ａ９０尖晶石在高ＦｅＯ（质量分数为１５％）含量的熔融还原炉渣中可以吸收渣中的ＦｅＯ形成高熔点的尖晶石固溶体，从而降低渣的侵蚀性，提高了材料的抗渣性。     

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.     

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.     

250 t钢包底吹氩卷渣和钢液裸露的模拟

针对某钢厂250 t钢包底吹氩气过程进行水模型实验和数值模拟,考察了吹气量和渣层厚度对卷渣行为和吹气量、渣层厚度及透气砖透气性能对钢液裸露面的影响,分析了卷渣形成机理. 结果表明,吹气量对卷渣形成具有决定性作用,吹气量控制在0.96 m3/h(对应实际流量69 m3/h)以下可避免卷渣;随着吹气量的增加,钢液裸露面积逐渐增大,当吹气量达到0.70 m3/h时,钢液裸露面积百分比约达14%,继续增大吹气量,其增加幅度变缓;随着渣层厚度的增加,临界卷渣吹气量和钢液裸露面积逐渐减小,以37 mm(对应实际渣厚150 mm)厚渣层覆盖,可有效防止钢液二次氧化;透气砖堵塞对钢液裸露面积影响较大,顶部钢液形成两不同大小的裸露亮圈,并加重对包壁耐材的冲刷与侵蚀,降低钢的洁净度. 工艺优化后,钢包水口结瘤率降低至0.1%以下,且可降低生产成本.     

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)。     

Research on the corrosion behavior of low carbon mold flux on submerged nozzle refractory

In this paper, the wetting and corrosion behavior between medium and low carbon mold flux and Al₂O₃-ZrO₂-C nozzle refractory were studied through a high-temperature wetting experiment. Combined with microstructure analysis, the corrosion mechanism of low carbon mold flux on nozzle slag line material was clarified. The results show that the wettability of low-carbon mold flux and Al₂O₃-ZrO₂-C nozzle refractory is better, compared with the traditional medium carbon mold flux, the contact angle between low-carbon mold flux and Al₂O₃-ZrO₂-C material is smaller and the mold flux spreads faster on the nozzle surface at the same temperature range. According to the microstructure analysis, the corrosion degree of low-carbon protective slag on the ZrO₂-C material of the nozzle slag line is serious, and the corrosion depth is large. Due to the influence of carbon content, the wettability between low-carbon mold flux and ZrO₂-C material of the nozzle slag line is better, which provides favorable kinetic conditions for the dissolution and penetration of low-carbon mold flux into the nozzle. In addition, compared with medium carbon slag, the carbon concentration difference between low-carbon mold flux and nozzle material is larger, resulting in greater diffusion driving force of carbon atoms, which affects the wetting, dissolution, and chemical reaction of the interface between the two phases.     

Process simulation and energy integration in the mineral carbonation of blast furnace slag

Large quantities of blast furnace(BF) slag and CO_2 are discharged annually from iron and steel industries, along with a large amount of waste heat.The mineral carbonation of BF slag can not only reduce emissions of solid waste but also realize the in-situ fixation of CO_2 with low energy consumption if integrated with the waste heat utilization.In this study, based on our previous works, Aspen Plus was employed to simulate and optimize the carbonation process and integrate the process energy.The effects of gehlenite extraction, MgSO_4 carbonation,and aluminum ammonium sulfate crystallization were studied systematically.The simulation results demonstrate that 2.57 kg of BF slag can sequester 1 kg of CO_2, requiring 5.34 MJ of energy(3.3 MJ heat and 2.04 MJ electricity), and this energy includes the capture of CO_2 from industrial flue gases.Approximately 60 kg net CO_2 emission reduction could be achieved for the disposal of one ton of BF slag.In addition, the by-product,aluminum ammonium sulfate, is a high value-added product.Preliminary economic analysis indicates that the profit for the whole process is 1127 CNY per ton of BF slag processed.     

Novel Stopper Designs to Improve Argon Purging Efficiency in Slab Casting

In order to ensure consistent argon flow in the stopper gas channel and improve argon bubble performance in the slab casting mould,two patented new technologies CSC(Clean Stream Cartridge) and SHP(Slot Hole Plug) were applied in the argon purging stopper designs.The novel stopper designs can maintain a stable back pressure and argon flow in the argon line during long sequence casting,eliminate pressure increasing at the start of the casting,even distribute gas bubbles in the mould leading to improved mould flux melting and lubrication,reduce mould level fluctuation and so on.     

Densification and microstructure evolution during sintering of silicon under controlled water vapor pressure

Sintering of fine silicon powder was studied under controlled water vapor pressures using the Temperature–Pressure–Sintering Diagram approach. The water vapor pressure surrounding the sample was deduced from thermogravimetric analysis and related to the water content of the incoming gas flux with a simple mass transfer model. The thickness of the silica layer covering silicon particles was then monitored by the water vapor pressure and the microstructure evolution and densification during sintering could be controlled. Stabilizing the silica layer indeed inhibits grain coarsening and allows better densification of the compacts under humidified atmosphere as compared to dry atmosphere.     

Quantum chemical calculations of the thermochemistry of tantalum oxyhydroxide species

Tantalum pentoxide and water vapor are predicted to react at elevated temperatures to form TaO(OH)₃(g), TaO₂(OH)(g), and Ta(OH)₅(g). The thermochemistry of these species is calculated with quantum chemistry methods. Geometries and vibrational frequencies are determined from B3LYP DFT methods. Energetics are calculated from high levels of theory—CCSD(T) and larger basis sets for Ta, O, and H. We report the enthalpies of formation at 0 K and 298.15 K, entropy at 298.15 K, and heat capacity. These quantities are used to calculate vapor pressures at 1400-1800 K and 50% water vapor. TaO(OH)₃(g) is found to be the dominant species. The calculated vapor pressure of TaO(OH)₃(g) is converted to a vapor flux and compared to previous experimental flux measurements from a flat plate in a slowly flowing H₂O/Ar gas and also vapor flux from a steam jet experiment. These “open system” experiments result in lower fluxes that are within 1.12-17X of the calculated equilibrium fluxes. This suggests that the experimental measurements are near equilibrium or have a small kinetic barrier.