Development and Application of High Quality Magnesite—Chrome Bricks fro VOD Refining Furnace

The paper describe the process of producing high quality magnesite-chrome bricks for VOD refining furnace,The Service life reaches 14 heasts,average life 12 heats.The studies show that the wear of the magnesite-chrome bricks is mainly due to chemical corrosion,thermal spalling induced by thermal shock and the corro-sion aroused from accumulation of molten mate-rials in transitional zone.     

Application of Semi—rebonded Magnesite—Chrome Bricks of LRF at RH Lower Vessl of NKK Keihin Wroks

The application results of semi-rebonded magnesite-chrome bricks at RH lowe vessel of NKK Corporation Keihin Works have been analysed,The results indicate that the main reasons that cause the damage of the refactory brcks include:chemical attack of slage to the semi-rebonded magnesite-chrome bricks;pene-tration of molten stel,slag into the bricks;and therma spalling due to temperature fluctua-tion during steel making operation.The results of multiple effection of these factors lead to alternative action of erosion(chemical attack and penetration)and spalling(thermal spalling and structure peeling) resulting in the damage of the brik ,In order to improve the performance of the bricks ,it is necessary to promote the resistance to erosion and thermal shock resistance as well as to keep the accurate dimensions of the brick,The measures of improvement of resistance to erosion of magne-site-chrome bricks taken by the researches mainly include:lowering the contents of impu-rities in the bricks(mainly including SiO2,CaO,and next Fe2O3 and Al2O3);promoting the extent of direct bond of the brick;forming a large amount of magnesia-chrome composite spinel well-distributed in the bricks through adding a large amount of synthesized materi-als;enhancing the resistance to erosion by adding a little amount of high-effective additives,Improvement of thermal shock resistance of the bricks is mainly through introducing some additive to make a certain amount of mi-cro-cracks occur in the brick so as to obtain an effect of increasing toughnes or through for-mation of second high temperature solid phase in the brick by adopting additive,In addition,it is needed to improve the quality of the brick appearance and ensure accurate dimensions of the brick,The purpose of this paper is to further iprove the service life of the refractory bricks by making use of the improvement mea-sures taken on the basis of the analysis results of the used bricks.     

Study on Mechanism of Reaction Between AOD Slag and Rebonded Magnesite—Chrome Brick

The influence of the composition of AOD slag on the corrosion of rebonded magnesite-chrome brick has been studied by analyzing the residual bricks at the tuyere zone of AOD .It indicates that the corrosion degree increased with the increase of the basicity of slag and decreased with the increase of the content of MgO ,Cr2O3 and Al2O3 in slag.And the addition of refractories to slag up to satura-tion could decrease the corrosion abiliy of sag.It is important to make a resonable slagmaking rule and ensure the percentage of MgO in slag more than 11wt% for pro-longing the service life of lining.     

Development and Application of High Quality Magnesite—Chrome Bricks for VOD Refining Furnaces

The paper describes the process of producing high quality magnesite-chrome bricks for VOD re-fining furnace,The service life reaches 14 heats,average life 12 heats.The studies show that the wear of the magnesity-chrome bricks is mainly due to chemical corrosion,thermal spalling induced by thermal shock and the corrosion aroused from accumulation of molten materials in transition zone.     

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.     

Dissolution Kinetics of Magnesitic-Dolomite and Magnesite-Chrome Refractories in Secondary Steelmaking Slags

Dissolution kinetics of magnesitic-dolomite and magnesite-chrome refractories in secondary steelmaking slags was studied by means of the rotating cylinder method under forced convection. Materials investigated include four magnesitic-dolomite samples(MgO content 40% to 93%)and two magnesite-chrome samples (co-clinkered and semi-rebonded).Synthetic slags simulative of VOD and AOD slags with varying basicity (0.6-2.68) are used.The experiments are carried out in Ar atmosphere at different temperatures (1 600 ℃-1 750 ℃) and revolution speeds (200 r·min-1to 500 r·min-1).The microstructure of specimens (before and after slag tests) are studied by optical microscopy, SEM and EPMA. Based on our experimental results the mechanism and kinetics of the dissolution process are discussed.     

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...     

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。     

玻璃窑用锆英石砖的研制

分析了几种代表性锆英石砖,指出影响锆英石砖性能的关键是骨料。详细介绍了玻璃窑用锆英石砖的生产过程及产品性能。     

Corrosion Mechanism of MgO-CaO Brick for AOD Furnace

In recent years burnt MgO-CaO brick have a-chieved a good application in AOD furnace[1].Thiswork analyzed the microstructure of residual MgO-CaObricks after being used in AOD furnace and discussedthe corrosion mechanism,which provides a theoreticalfoundat…     

镁钙炭砖在LF-VD精炼炉渣线部位的试用

天津钢管公司150tLF－VD精炼炉渣线部位成功地试用了不烧镁钙炭砖,平均寿命达20炉。实现了与炉身铝镁炭砖同步,解决了几年来使用镁炭砖必须拆砌一次渣线砖的问题,大大降低了耐火材料消耗和费用,提高了精炼炉作业率。     

碳复合砖抗氧化性能研究

对高炉炉缸炉底用碳复合砖在空气环境下的抗氧化性能进行热力学分析和动力学分析.热力学分析结果表明,温度在800～1100 K内,主要发生的是C的氧化反应;温度在1100～1500 K内,主要发生的是SiC的氧化反应和石墨C的氧化反应.氧化实验结果表明,温度为600℃时,反应始终由C-O反应控速;温度为800℃以上时,控速环节逐渐转变为O2的扩散,且随着温度升高,O2扩散的阻力越大.     

镁铬耐火材料在真空条件下的抗渣性

采用真空感应炉抗渣法,研究了半再结合镁铬耐火材料在碱度分别为0.6、1.1、1.5和1.8的CaO-SiO2渣与Al2O3含量为37.98%的CaO-Al2O3渣中的抗侵蚀性,试验条件是真空度5kPa、1650℃保温25min。对侵蚀后的试样进行观察与测量,并用SEM与EDAX分析了试样的断面形貌和化学组成变化。结果发现:在CaO-SiO2渣中,随着炉渣碱度的升高,镁铬试样中的尖晶石更易于受到熔渣的侵蚀,并且尖晶石中的Cr2O3、Fe2O3被CO与钢水中的C还原为金属态的铬铁合金,试样的直接结合被破坏,侵蚀量变大。在CaO-Al2O3渣中,镁铬试样在边界层生成致密的MA尖晶石,抑制了熔渣的进一步侵蚀和Cr2O3、Fe2O3的还原,显示出较好的抗侵蚀性。     

镁钙系耐火材料在炉外精炼炉上的应用

综述了镁钙砂、烧成镁钙砖和不烧镁钙碳砖等镁钙系耐火材料的发展现状、生产工艺及性能,介绍了镁钙系材料在AOD炉、VOD炉、LF-VD炉、GOR炉等炉外精炼炉上的应用情况。