镁质-铝镁质复合型挡渣墙的研制

为了提高镁质挡渣墙使用寿命,设计在其渣线和钢水区分别采用铝镁质和镁质浇注料制成复合型挡渣墙,因此对原挡渣墙用镁质浇注料的施工性能进行了改善,并选择合适的振动成型工艺将其与铝镁质浇注料复合在一起制作了复合型挡渣墙试样。结果表明:(1)通过调整缓凝剂和减水剂以及选用适当的SiO2微粉,可以改进镁质浇注料的施工性能和硬化性能,使其与铝镁质浇注料相匹配;(2)铝镁浇注料与改进后的镁质浇注料,无论采用上下复合(立振)还是水平复合(平振),都可以制作复合型挡渣墙,为了达到振动充分和两材质的界面波动幅度适当,平振时以振动2.5min为宜,立振时以两材质浇注料接触后再振动3min为宜;(3)现场使用试验表明,研制的复合型挡渣墙达到了既减少对钢水的污染又大幅度提高抗侵蚀性能的设计目标。     

引入SiC提高中间包镁质挡渣墙高温使用性能

通过对引入SiC的镁质挡渣墙理化指标检测和用后残砖分析,认为引入SiC能够很好地改善镁质中间包挡渣墙高温体积稳定性和抗侵蚀性,减少挡渣墙使用中出现的断裂和侵蚀问题,提高镁质挡渣墙在高温钢水中的使用性能。     

中间包用碱性挡渣堰砖的开发与应用

在炼钢工艺中为了开发中间包用高性能碱性挡渣堰砖,研究了原料、结合剂和添加剂对镁质浇注料的水化和高温性能的影响。高铝水泥结合的镁质浇注料,在干燥过程中由于镁砂的水化作用而引起裂纹的发生和扩展,通过使用尖晶石砂代替氧化镁粉使水化得到了抑制。以Na_2O·2CaO·P_2O_5(NC_2P)结合的浇注料,虽然没有因镁砂的水化而产生裂纹,但是高温抗折强度变低。在高温下NC_2P结合的浇注料的机械性能通过使用SiO_2含量低的镁砂而得到了改进。     

塔塔钢厂对挡渣堰用耐火材料的探讨

连铸中间包采用高铝质挡渣堰，通常用于使钢水按照流体学处于最佳流动状态，使钢水中夹杂物上浮，达到净化钢水的效果。塔塔钢厂经过艰夺的努力研制出了低成本适用的镁质挡渣堰。将镁质挡渣堰的特点与高铝质挡渣堰进行了比较。由于钢水洁净度提高、成本低的特点，因而比高铝堰受到欢迎。本文重点了介绍了镁质挡渣堰用适宜原料的选择，例如：烧结镁砂等，造反混合好氧化物（硅酸盐）的品位，使之在高温形成镁橄榄石结合，选择非氧化物     

铝镁尖晶石对镁质浇注料性能的影响

针对镁质浇注料在使用过程中抗渣渗透能力差,易剥落等问题,本实验加入铝镁尖晶石对镁质浇注料进行改性研究.实验分为两部分:先将镁砂细粉、镁质添加剂和铝镁尖晶石细粉等机压成型,进行高温热处理,研究其物相组成和显微结构;然后以电熔镁砂为骨料,电熔镁砂细粉、氧化铝微粉、铝镁尖晶石细粉和镁质添加剂为基质,按骨料:细粉=75∶25进行配制,研究铝镁尖晶石加入量对镁质浇注料性能的影响.结果表明:在镁质材料中引入尖晶石,能促进结构致密化;加入9％的铝镁尖晶石的浇注料试样显气孔率低,线变化率小,体积密度大,强度大,抗渣性能最好,由于镁铝尖晶石生成时体积膨胀,使得材料结构致密化;同时能有效吸收渣中CaO及FeOx等成分,减少渣的渗透作用,从而提高了浇注料的抗渣性能.     

中间包镁质干式振动料抗渣性能研究

以粒度为3~1、≤1、≤0.088 mm的中档烧结镁砂为主要原料,按骨料与基质的质量比65 35配料,选用糖、硅酸钠为复合结合剂制备了镁质干式振动料试样。采用静态坩埚法研究了糖、硅酸钠加入量和添加剂(分别为铝矾土粉,α-A l2O3粉)对干式振动料抗渣性能的影响。结果表明:1)糖、硅酸钠复合加入对镁质干式振动料抗渣性能不利,糖和硅酸钠加入量(w)分别为4%和2%时相对最好;2)镁质干式振动料的渣蚀过程以渗透为主;引入高铝矾土粉和α-A l2O3粉均可与镁砂(MgO)高温下反应生成的尖晶石(MA)可以显著提高干式振动料的抗渣性能。     

不同添加剂对镁质浇注料性能的影响

以电熔镁砂和高纯镁砂为主要原料制备了镁质浇注料,研究了不同添加剂对镁质浇注料性能的影响。研究结果表明,5种添加剂中,加入氧化铝微粉的镁质浇注料经1 100℃和1 500℃烧后的体积密度最大,浇注料基质中形成的方镁石/镁铝尖晶石复相结构有利于提高试样的抗热震性。加入氧化铬、铝铬渣和焦宝石的镁质浇注料,其抗热震性均高于未加入添加剂的镁质浇注料的该项性能。     

Si3N4对镁质浇注料抗渣性能的影响

以95烧结镁砂为主要原料,以SiO2微粉为结合剂,在配料的细粉部分分别以0、3%、4%、5%的β-Si3N4细粉替代等量的镁砂细粉,搅拌均匀后浇注成氮化硅含量不同的镁质坩埚试样。选用宝钢中间包渣,采用静态坩埚法,在1550℃3h条件下对这些坩埚试样进行了抗渣试验。试验结果表明:加入Si3N4可以明显改善镁质浇注料的抗渣性能,并且随着Si3N4加入量的增加,试样的抗渣性能提高;在含氮化硅的镁质浇注料表面,由于Si3N4被氧化为SiO2而形成了致密烧结层,能阻止渣的进一步渗透;在加入Si3N4的镁质浇注料试样内部深处,由于氧分压非常低,Si3N4稳定存在;由于Si3N4在还原气氛下难以烧结,造成镁质浇注料内部结构疏松。     

镁质弥散型透气材料用镁砂原料的选择

为了选取适合制备镁质弥散型透气材料的镁砂原料,分别以4种不同镁砂(电熔镁砂、高纯镁砂、中档镁砂、普通烧结镁砂)、镁铝尖晶石和α-Al_2O_3为原料,经配料、成型、干燥和1 650℃保温3 h烧制成镁质弥散型透气材料。研究了4种不同镁砂原料对镁质弥散型透气材料致密度、透气度、强度等性能以及显微结构的影响。结果表明:以电熔镁砂和中档镁砂为原料的试样具有良好的透气性和强度,但热膨胀系数相对较高,试样的抗热震性差;以普通烧结镁砂为原料的试样热膨胀系数最低,且具有较好的抗热震性,但透气度和强度都相对较低;以高纯镁砂为原料的试样具有较高的常温强度和高温强度,透气性能最好,热膨胀系数较低,有利于提高材料的抗热震性。综合考虑镁质弥散型透气材料的各项性能,应选取高纯镁砂为原料。     

连铸中间包用环保型镁质干式料的开发

分别以98电熔镁砂和95烧结镁砂为原料,按骨料与基质料的质量比70:30配料,并外加不同量环保型无机结合剂Na2SiO3.9H2O制成试样,200℃3 h烘干后,分别于1 100℃3 h和1 550℃3 h进行热处理。通过常温性能检测、显微结构观察,研究了镁砂原料的种类及结合剂Na2SiO3.9H2O的添加量(质量分数分别为4%、5%、6%、7%)对镁质干式料性能的影响,并采用静态坩埚法评价了试样的抗渣性能。结果表明:(1)以电熔镁砂为原料的试样,其常温物理性能优于烧结镁砂的;(2)结合剂Na2SiO3.9H2O的适宜添加量为5%;(3)Na2SiO3.9H2O结合的试样其抗渣性能优于酚醛树脂结合的;(4)渣蚀过程以渗透为主,在渗透的过程中,方镁石与熔渣反应,使熔渣的黏度增大,减缓了其进一步渗透。     

Research on Composite Slag Dam Cast with Magnesia Castables and Alumina Magnesia Castables

To enhance the service life of magnesia based slag dam,composite slag dam was designed to be cast with alumina magnesia castables in slag line and magnesia castables in molten steel zone.Workability of the magnesia castables for the slag dam was improved and a suitable vibration shaping method was adopted to combine it with alumina magnesia castables.The result shows:(1)workability and setting performance of magnesia castables can be improved to match with alumina magnesia castables by adjusting setting ret...     

不同碳含量对镁碳砖性能的影响

研究了碳含量的变化对镁碳砖抗渣侵蚀性、抗氧化性能、高温抗折强度和热震稳定性的影响。研究结果表明：随碳含量增加,镁碳砖的体积密度、耐压强度降低;碳含量在6%~8%时,镁碳砖的高温抗折强度、热震稳定性、抗渣侵蚀性及抗氧化性能好;碳含量低,镁碳砖的抗渣侵蚀性降低;碳含量为14%时,镁碳砖的抗氧化性能最差。     

锆英石微粉对镁质浇注料性能的影响

研究了锆英石微粉对镁质浇注料结构及性能的影响。结果表明：微粉粒径一定时,控制锆英石微粉加入量可以明显改善镁质浇注料显微结构和性能。由于MgO同ZrSiO4反应形成的ZrO2,能吸收渣中的CaO形成CaZrO3,堵塞材料中的气孔,同时提高熔海粘度,抑制了渣的渗透。     

富铝尖晶石对镁质耐火材料抗侵蚀性的影响

研究了富铝尖晶石对镁质耐火材料抗钢渣与抗钙处理钢侵蚀性的影响。结果表明 :随着富铝尖晶石加入量的增加 ,镁质耐火材料的抗钙处理钢和钢渣熔蚀性逐渐减弱 ,而抗钢渣渗透性逐渐增强 ;纯镁质和镁尖晶石质耐火材料在抗钢渣与抗钙处理钢侵蚀方面远远优于铝锆碳质材料     

钢包渣线用MgO-尖晶石-Cr_2O_3浇注料的研制与应用

以镁砂、电熔白刚玉、矾土熟料、尖晶石等为主要原料,研究了Ｃｒ２Ｏ３对ＭｇＯ尖晶石浇注料常温物理性能、荷重软化温度、抗渣和抗热震性的影响,开发出了ＭｇＯ尖晶石Ｃｒ２Ｏ３浇注料。在某钢厂９０ｔＲＨ精炼钢包渣线部位使用,平均一次性寿命达９６．５次     

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.     

Corrosion modeling of magnesia aggregates in contact with CaO–MgO–SiO2 slags

Ladle refining is an efficient process for improvement of quality of steel on secondary metallurgy under harsh conditions. Magnesia refractories with high purity are important raw materials for ladle lining in high-quality steel production. However, the penetration by CaO–MgO–SiO₂ slags damages magnesia refractories, which considerably limits their service life. Abundant grain boundaries in magnesia create channels for slag penetration and lead to the destruction of the structure. The effect of the microstructure on the slag corrosion behavior of magnesia aggregates requires further systematic investigation. In this study, a corrosion model was established to describe the slag penetration process of magnesia aggregates. The effects of the grain-boundary size and slag CaO/SiO₂ mass ratio (C/S ratio) on slag penetration were investigated, and the possibility of the microstructure optimization of magnesia aggregates was discussed. The results indicated that magnesia aggregates exhibited excellent slag resistance for slag with a C/S ratio above 1.5 or even 2.0. When the slag C/S ratio was lower than 1.5, the dissolution rate of magnesia decreased more rapidly with the increase in the slag C/S ratio. In addition, the much smaller grain-boundary size increased the slag penetration resistance by promoting the formation of a dense isolation layer and inhibiting further penetration processes. The calculation results agreed well with the experimental results, suggesting that the corrosion model is promising for predicting slag corrosion.     

TiO_2对镁铬砖抗渣蚀性的影响

利用XRD分析和光学显微镜等测试手段 ,研究了添加TiO2 对镁铬砖抗渣蚀性的影响。结果表明 :炉渣中的CaO能分解镁铬砖中的二次尖晶石而使镁铬砖损毁 ,但加入TiO2 后 ,TiO2 能优先于尖晶石中的Cr2 O3与渣中CaO反应 ,生成高熔点的CaTiO3,从而抑制CaO对砖中镁铬尖晶石的分解 ,提高了镁铬砖的抗高钙渣渣蚀能力     

Corrosion Resistance Mechanism of Magnesia Zirconia Brick to RH Furnace Slag

Magnesia zirconia brick containing 11 wt% zirconia was prepared with magnesia and monoclinic zirconia as starting materials in order to replace the chrome-containing materials for RH furnace.The corrosion resistance of magnesia zirconia brick and fused rebonded magnesia chrome brick (short for magnesia chrome brick) to high and low basicity slag of RH furnace was comparatively researched by rotary slag method and their slag resistance mechanisms were analyzed.The results show that:(1) because the reaction l...     

Interface behaviour and corrosion behaviour of magnesia refractory by alkaline slag in an alkali recovery furnace

The adhesion of Na₂CO₃ slag to the surface of refractories in an alkali recovery furnace can cause corrosion and spall. Magnesia refractories can be used as linings in alkali recovery furnaces owing to their strong corrosion resistance to alkali slag. However, the permeability resistance of magnesia refractories is relatively poor. Hence, the interface and corrosion behaviours of slag cladding on magnesia refractories were studied using sessile drop and static crucible tests. The experimental results showed that an increase in the heating rate positively affected the cladding of the molten column on the refractory surface. The microstructure, element changes, and chemical composition changes of the corroded refractories were analysed using SEM-EDS and XRD. Thermodynamic simulation of the reaction between the slag and refractory was performed using Factsage 7.3. The results indicate that the generated forsterite filled the pores of the magnesia refractories. The microstructure of dense slag-refractory interface layer was formed, which prevented the infiltration of slag phases and alleviated the corrosion of refractories by the slag.