Study of penetration and corrosion of olivine–periclase and periclase based tundish DVMs by molten slag

Abstract

To enhance the billet caster tundish life, this study examines the relevance of the replacement of regularly used olivine–periclase based mixes by purer MgO containing dry vibe mass (DVM). After service, tundish working lining samples were studied by scanning electron microscopy energy dispersive spectroscopy to understand the influence of MgO saturation of the adhering slag and working lining interaction with the infiltrated slag. The result showed that the tundish working lining was penetrated and corroded by the molten slag for both DVM recipes. However, an increase in MgO content in the DVM exerted a chemical filtration to the molten slag, and the higher concentration of periclase dissolved into the slag, forming a saturated layer at the slag/refractory interface that resulted in the restriction of further slag penetration, probably due to an increase in the slag viscosity.     

微孔MgO耐火材料对钢液洁净度的影响

摘要：通过浸泡实验研究了3种镁质（致密镁质、微孔MgO质、镁碳质）耐火材料与超低碳钢液(1560℃)的相互作用,考察了不同浸泡时间(0～35min)钢中O、N、C和Al、Si、Mn含量及钢中夹杂物的成分、数量、分布等特征的变化,并对耐火材料与钢的界面层进行了观测和分析。结果表明,随着浸泡时间的延长,3组钢中氧含量均先升高再降低,均对钢液有一定的污染,钢中夹杂物的数量增加,夹杂物种类由Al2O3-MnO夹杂逐渐转变为Al-Mg-Si-Mn-O复合夹杂。与致密镁质耐火材料相比,微孔MgO质和镁碳质耐火材料与钢的界面处分别能形成连续的镁铝尖晶石层和致密的MgO层,有助于降低耐火材料的侵蚀以及对钢液的污染。此外,与不含碳的镁质耐火材料相比,镁碳质耐火材料对钢液增碳严重。因此,微孔MgO质耐火材料不仅对钢液的二次污染小、不会向钢液增碳,而且还可以吸附钢中氧化铝夹杂,更有利于超低碳洁净钢的生产。     

碱性干式自流料在方坯连铸中间罐上的应用实践

为适应高效连铸和开发新品种的需要，邯钢第三炼钢厂方坯连铸中间包工作层用碱性干式自流料取代了硅质绝热板。生产实践表明，它在提高中间包使用寿命、降低钢水消耗、减少夹杂废品量、降低耐火材料消耗及降低劳动强度等方面具有明显优势。     

MgO–C bricks for BOF linings

Abstract

MgO–C brick linings have become standard in basic oxygen furnaces (BOFs) all over the world. Developments in the refractory technology for BOFs over the last few years and their impact on the lifetime and performance of refractory linings are presented. These developments comprise optimised shapes for the lining of BOF and steel fibre reinforced MgO–C bricks. Optimised shapes with double wedges lead to a smooth inner surface of the refractory lining and fewer stresses and refractory consumption. Stainless steel fibre reinforced MgO–C bricks have proven to be the ultimate choice for scrap impacts or other areas with ultra high mechanical loads. They have brought down refractory wear in these particular areas significantly. Moreover, typical lining patterns of different zones in a BOF and the development of the raw material grades (MgO grades and graphite) for refractories as well as the development of lining lifetimes over the last years are discussed.     

中间包覆盖剂及内衬材料对钢水清洁度的影响

阐述近年国内外中间包覆盖剂内衬材料的发展情况，研究中间包覆盖剂地夹杂物的吸附、钢水的氧化和对钢卷渣及钢水脱硫的影响；讨论酸性内衬及碱性内衬对钢水清洁度的不同效果。结论：高碱性、成分、结构合适的中间包覆盖剂及内衬材料是生产高洁净钢的重要条件。．     

耐火材料对钢水纯净度影响的试验研究

通过对钢包、中间包衬层内示踪剂在浇铸过程中变化的试验分析，判断衬层耐火材料在钢水中的变化情况，分析每炉钢水对耐火材料的冲刷量及耐火材料对钢水纯净度的影响程度。从而提出减少耐火材料衬层对钢水污染的措施。     

钢包耐火材料与钢液反应的研究现状

随着国家工业的快速发展,对高品质钢的需求增大,侵蚀的耐火材料作为钢中外来夹杂物的主要来源受到广泛关注.基于此,阐述了耐火材料与钢液的反应机制、不同耐火材料与钢液的相互作用以及对钢液质量造成的影响.耐火材料会向钢中溶解并与钢中成分发生反应,之后形成界面层,当界面层是高熔点物质时,会阻碍耐火材料的溶解扩散,当界面层是低熔点...     

新型纳米级微孔隔热材料在炼钢生产中的应用

唐山中厚板材有限公司针对炼钢生产中钢水热量损失过大问题,在转炉、钢包和中间包上,系统采用了新型WDS纳米级微孔隔热材料,提高了耐火衬的蓄热量,在不影响耐火材料使用寿命的情况下,转炉的终点温度提高了7℃,从转炉、钢包到LF炉过程温降速度减小了0.3℃/min,采取降低LF炉出站温度5℃的方式,中间包后期钢水温度仍然能够满足连铸工艺需要,达到了节能降耗的目的,可以产生综合经济效益1480万元/a。     

我国连铸中间包内衬耐火材料的发展及应用

介绍了我国连铸中间包内衬耐火材料的发展和使用状况。我国连铸中间包内衬耐火材料由黏土砖、高铝砖发展到硅质绝热板、镁质绝热板、碱性涂料和碱性干式振动料等,这些耐火材料用在不同类型的连铸中间包上,取得了良好的效果,满足了我国不同时期连铸生产的需要。     

连铸中间罐镁质涂料工作衬的实践与体会

本文介绍了连铸中间罐采用镁质涂料工作衬的实践情况。实践证明，采用涂料作工作衬具有施工简便、提高钢的质量、安全可靠及相对减轻劳动强度、延长中间罐使用寿命、降低耐材消耗等优点。对促进连铸生产的发展，具有重要意义。     

无碳新技术钢包及在济钢的应用

为满足品种钢开发要求,降低耐材消耗,济钢采用了无碳新技术钢包,即采用无碳预制件砌筑包壁,包底整体浇注打结,运行过程中进行4～6次喷补小修。新技术喷补料修砌喷补后,在高温下与包壁预制件变质层的矿物相进行互相渗透、互相反应,生成具有优良性能的反应层,从而把使用过的变质层与新喷补层牢固地粘接在一起,形成的衬体达到与原有预制件相同的使用效果,抗侵蚀耐冲刷,平均寿命达到175炉以上。     

功能化新型耐火材料的设计、制备及应用

围绕两种新型耐火材料展开,即钢包精炼用高性能低碳镁碳耐火材料以及超低氧钢用耐火材料,初步实验表明,将大尺寸的碳硅化铝（Al₄SiC₄）引入到镁碳砖（MgO?C）中不仅可以提高其抗氧化能力,又能对含碳耐火材料氧化后的疏松结构进行修复,有望成为新一代钢包精炼用高性能低碳镁碳耐火材料;CaO?MgO?Al₂O₃（CMA）材料兼具优异的热机械和耐渣侵性能的同时,还可以在服役过程产生低熔点精炼渣相,具备净化钢水的潜力。可以预见,上述功能化新型耐火材料有望为高品质钢的进一步发展提供有力材料支撑。      

Interaction of alumina inclusions in steel with calcium-containing materials

Clogging of tundish and submerged entry nozzles (SENs) adversely impacts productivity and quality in the continuous casting of aluminum-killed steels. Clogging results from an accretion layer that develops on the inside surface of the nozzle and restricts steel flow. Current nozzle refractories often react with molten steel to form solid by products that promote clogging. Nozzle materials that are inert with the liquid steel or react with accretions to form liquid reaction products could inhibit or eliminate clogging. Static experiments were conducted to investigate the stability between calcium-based materials and aluminum-killed steel. The results indicate that both calcium titanate and calcium zirconate react with alumina to form calcium aluminates. However, only the reaction between alumina and calcium titanate yielded calcium aluminate chemistries that were molten at steel casting temperatures. Liquid reaction products are preferred since they would be removed from the nozzle by the steel flow, thereby preventing accretion formation and clogging.     

Characteristic Analysis of Solidified Crust for Basic Tundish Flux With Al-Killed Steel Casting

The solidified crust was harmful to Al-killed steel casting using a basic tundish flux. After sampling from an actual tundish, XRD, SEM and EDX examinations were carried out to analyze the microstructure of solidified crusts. The conclusions were obtained as follows: main crystallization phases existing in tundish crust were Ca12A14 O33, Ca2SiO4 and a little spinel; spinel and Ca2SiO4 distributed between the grain boundaries of Ca12A14O33,which increased the connection strength of crystallization phases by pinning grain boundary, density or hardness of solidified crust maybe also significantly increases; when initial composition of tundish flux was located in spinel region of CaO-SiO2-Al2O3-10%MgO phase diagram, it was easier to precipitate spinel from molten slag; three approaches of spinel formation in flux were summarized. When flux was saturated with magnesia on the metal/flux interface, MgO in flux was reduced by dissolved aluminum and then formed spinel. On the interface of steel/refractory,with feasible aluminum content, it was also easy to form spinel, and spinel inclusions will be floated and captured bytundish flux.     

钢包内衬用耐火材料对钢中非金属夹杂物的影响

 炉外精炼是炼钢流程中控制钢中非金属夹杂物的重要转折点,作为整个精炼过程中与钢液实时接触的钢包内衬用耐火材料,因为高温物理化学反应易向钢中引入夹杂物,导致精炼效果达不到预期。通过对典型现役钢包内衬用耐火材料与不同脱氧钢之间的界面反应归纳发现,钢包内衬用耐火材料会对钢中夹杂物的形貌、成分和理化性能产生影响,既可向钢中引入夹杂物,也能够吸附去除夹杂物。提出未来钢包内衬用耐火材料应被赋予更多净化钢液等功能指标的发展方向。     

钢包工作衬用耐火材料的研究现状及最新进展

综述了近年来钢包工作衬用耐火材料的研究现状及最新进展, 尤其对传统钢包工作衬用耐火材料的应用背景及存在问题进行了分析和汇总.在此基础上, 进一步提出了适用于超低氧钢(或洁净钢)冶炼用耐火材料的研发方向, 即通过耐火原料组分选择和结构匹配设计, 实现对耐火材料性能的精确控制.新型钢包工作衬用耐火材料需兼顾优异热机械性能的同时, 还应具备钢水净化的功能.      

连铸用功能耐火材料的发展

介绍了钢铁连铸用浸入式水口、中包水口、长水口及塞棒等功能耐火材料的发展现状,指出今后的研究重点应是通过复合抗冲刷性能优良且透气性能好的内衬料,解决快换中包水口内衬不抗冲刷、容易向内衬中渗钢水、吹氩效果不理想的问题,开发多功能、高性能和长寿命的连铸用耐火材料.     

MgO与低密度钢液相互作用及其对夹杂物的影响

 为了研究高锰高铝低密度钢液与耐火材料间的相互作用规律,以Fe-20Mn-10Al-C(20%Mn、10%Al)低密度钢液与MgO耐火材料棒在1 600 ℃时界面反应为研究对象,分别反应30和60 min后对MgO耐火材料的微观结构以及钢中非金属夹杂物特征进行了观察。结果表明,反应后MgO耐火材料转变为3层结构,分别为致密的MgO·Al₂O₃尖晶石界面层,尖晶石颗粒、钙铝酸盐和MgO颗粒组成的过渡层以及MgO颗粒组成的原始层,且随着反应时间的增加,尖晶石界面层厚度增加;在高锰高铝低密度钢液与MgO耐火材料的相互作用下,钢中非金属夹杂物主要包括单一MgO·Al₂O₃夹杂、AlN夹杂、MgS夹杂和MgO·Al₂O₃-AlN、MgO·Al₂O₃-MgS等复合夹杂物。     

Adhesive Behaviour of BOF Slag to BOF Lining Refractory in Slag Splashing Process

A slag layer is formed when slag is splashed onto refractory lining in BOF slag splashing process. The melting temperature of the slag layer and the adhesion of the slag layer to the lining refractory have an important effect on slag splashing and BOF lining life. This study investigates the adhesive behaviour of slag with different composition to lining refractories. It is shown that the slag can adhere to MgO particles in MgO‐C bricks well and no reaction is found between the MgO particles and the slag layer, but a gas gap exists at the interface between the slag layer and the MgO‐C matrix and there are iron granules within the slag layer, when the FeO content in the slag is high. The adhesion of the slag layer to the lining refractory can be improved with decreasing FeO content in the slag and lower carbon content in the MgO‐C bricks. BOF refractory lining life can be greatly increased due to better adhesion, high melting temperature, and stronger wear‐resistance of the slag layer.     

宝钢连铸中间包热状态测试与分析

连铸中间负愉钢水温度是炼钢生产过程的重要工艺参数之一,影响该参数的因素很多,通过对宝钢炼钢部60t中间包的包衬热状态进行测试,分析了包衬蓄热状况对中间包钢水温度的影响。