RH预熔型脱硫剂的开发与应用

针对Cao—CaF2系脱硫剂对RH浸渍管侵蚀严重、污染环境的缺点,开发出一种以CaO—Al2O3-SiO2渣系为主,添加部分高碱度、高硫容组分的预熔型脱硫剂。该脱硫剂现场试用结果表明,具有脱硫速度快、对真空槽侵蚀轻、脱硫率高的特点,平均脱硫率达到50％以上。     

提高真空炉浸渍管使用寿命的应用实践

研究了RH真空炉浸渍管用刚玉尖晶石浇注料的侵蚀机理。熔渣及钢液通过浇注料表面缺陷渗入其内部,与浇注料发生反应生产低熔点变质层,RH炉间歇式的生产特点,耐材温度频繁大幅度波动,因热膨胀系数的差异,在变质层和浇注料之间产生裂纹,在高速的冲刷作用下,造成耐火材料脱落;同时探讨提高硅钢用浸渍管使用寿命的途径。     

预熔型RH脱硫剂的开发与应用

针对CaO-CaF2系脱硫剂对RH浸渍管侵蚀严重、污染环境缺点,开发出一种以CaO-Al2O3-SiO2渣系为主,添加部分高碱度、高硫容组分的预熔型脱硫剂.现场试用结果表明:脱硫剂具有脱硫速度快、对真空槽侵蚀轻、脱硫率高的特点,平均脱硫率达到50 %以上.     

RH脱硫工业实践

通过研究选择适合的RH脱硫剂及相关工艺参数控制,RH脱硫剂的脱硫效率平均为30%,达到了较好的脱硫效果。试验炉次T[O]和[N]也控制较好。试验发现钢包进站顶渣的（FeO＋MnO）含量控制在12%以下,脱硫效果较好;增大脱硫剂中CaO含量有利于脱硫。试验中存在RH插入管、真空室底部及钢包内衬耐火材料的侵蚀较为严重的问题,需选择碱性耐火材料。     

硅微粉对RH浸渍管浇注料性能的影响

介绍了RH浸渍管浇注料的使用条件和损毁机理。探讨了硅微粉的加入对浇注料的热震稳定性、抗渣侵蚀性和热膨胀性的影响。结果表明，硅微粉的加入量为1．5％时，RH管浇注料的上述性能良好。     

攀钢RH浸渍管粘渣原因分析与对策

针对攀钢现行工艺下发生的RH浸渍管粘渣的问题,通过实验及理论计算研究了RH浸渍管的粘渣原因及其对策。对RH浸渍管粘渣物的物相分析结果表明,RH精炼过程中高熔点的镁铝尖晶石相在熔渣中析出是导致RH浸渍管粘渣的根本原因;精炼渣组成对浸渍管粘渣影响的研究表明,提高精炼渣的碱度、增大渣中CaO/Al2O3含量比、降低渣中MgO含量,可以降低渣中高熔点相的作用浓度,改善了熔渣粘度和熔点,有利于减轻RH浸渍管的粘渣。     

RH浸渍管粘渣形成原因及解决办法

通过成分和物相分析,探讨了硅钢冶炼过程RH浸渍管表面粘渣的形成原因,提出优化RH精炼渣成分的改进措施并开展了生产试验进行验证。结果表明:粘渣成分与RH终点渣成分相似,主要由Al_2O_3,CaO,Fe_xO_y,SiO_2和MgO等组成,形成的主要物相为铁铝尖晶石和钙铝黄长石;粘渣由高黏度、高熔点的RH精炼渣粘附在浸渍管上不断累积长大形成;增加RH炉渣中CaO含量,提高炉渣中CaO/Al_2O_3的含量比值,可降低炉渣的黏度和熔点,避免浸渍管表面粘渣的形成和长大。     

RH用低氟型CaO+Al_2O_3基熔剂深脱硫工业试验

采用低氟型CaO+Al2O3复合基熔剂替代传统CaO-CaF2系脱硫剂,利用RH投入法进行钢液深脱硫工业试验.20个试验炉次的结果表明,RH平均脱硫率ηS可达到53.44%,脱硫后钢液中[S]≤24×10-6.分析了钢包顶渣的改性处理以及RH脱硫终渣组成对RH脱硫的影响.在此基础上,确定了RH脱硫剂的优化组成为:CaO+BaO(60%～65%)–Al2O3 (20%～25%)-MgO (5%～7%)–CaF2(＜5%).     

RH浸渍管镁铬砖侵蚀分析

分析了影响RH浸渍管镁铬砖侵蚀速率的因素,采取了控制驱动气体流量、制定烘烤火焰标准、改变合金加入方式和提高浸渍管利用率等,使RH浸渍管正常情况下的使用炉次由78炉增加到了86炉,增加了10.25%,有效地降低了炼钢成本。     

RH炉浸渍管非对称腐蚀的数值模拟和应用

某钢厂 100 t RH炉存在上升管与下降管非对称腐蚀的问题,下部槽在上升管侧入口处的侵蚀远大于下降管侧出口处的侵蚀,无法满足设计的下部槽与浸渍管更换频率为1∶3的要求。通过数值模拟,对RH 炉吹气进行了流场模拟,得出了上升管和下降管的速度场分布,确定了该问题存在的原因是上升管与下降管内钢液的流速差异大,采取浸渍管对调等优化措施后,下部槽和浸渍管寿命分别达到 333和111炉,第3次浸渍管能与下部槽同步下线,降低了耐材成本。     

生产轴承钢用浸入式水口的堵塞机理

 由于生产轴承钢水口的堵塞,严重影响生产的顺利进行。利用化学分析、相分析和岩相分析的方法对浸入式水口堵塞物及其耐火材料进行研究。结果表明,发生水口堵塞的位置主要在水口渣线部,堵塞物化学成分主要以金属Fe为主,其它含有Al、Cr、Si、C等物质。而水口内壁物质主要是Al2O3、SiO2、CaO、Cr2O3、FeO等氧化物。从X射线分析看,这些物质主要是熔点较高的CaO和Al2O3形成的CaO·2Al2O3和CaO·6Al2O3。由此分析得出,钢水金属冷凝、连铸保护浇铸不好和钢水不洁净是造成水口堵塞的主要原因。同时给出了防止水口堵塞的技术措施。     

BOF-LF-CSP工艺生产SPHC钢的夹杂物演变

 通过热力学计算及转炉、LF炉、中间包、铸坯的系统取样与SEM、EDS等检测,对BOF-LF-CSP工艺生产的SPHC钢夹杂物在各工序的种类、数量、变性及组成进行了研究。结果表明,在BOF-LF-CSP过程中, 转炉终点夹杂物以Al2O3为主,在LF炉钙处理后钢水Al2O3夹杂的质量分数降低到铝处理后时的50%,出LF炉时钢中剩余的Al2O3夹杂基本完成了球化变性,并以铝酸钙复合物或硅酸盐结合的镁铝钙复合物为主,球化率约为72%;铸坯内夹杂物的平均粒径为5. 4μm、球化率为75. 8%。Al2O3经历了①Al2O3→CaO·6Al2O3→CaO·2Al2O3或CaO·Al2O3→12CaO·7Al2O3或CaO·3Al2O3;②Al2O3→MgO-Al2O3→MgO-Al2O3-CaO→MgO-Al2O3-CaO-SiO2的演变,正确合理的精炼工艺会使夹杂物充分上浮、球化及变形,提高钢水可浇性及钢材性能。     

MgO加入量对Al_2O_3-MgO浇注料抗渣性的影响

以电熔白刚玉为主要原料,同时加入电熔镁砂细粉、铝酸钙水泥、α-Al2O3微粉、Si O2微粉等,保持镁砂细粉与白刚玉粉总加入量一定,通过改变镁砂细粉的加入量,研究了镁砂细粉加入量对Al2O3-MgO浇注料抗渣性的影响。研究结果表明:在Al2O3-MgO浇注料中加入一定量的镁砂细粉,高温下可以形成镁铝尖晶石,从而提高浇注料的抗渣侵蚀性。当镁砂细粉加入量在2%～6%时,浇注料的抗渣侵蚀性能最好。     

Corrosion behavior of high alumina and low silicon CaO Al2O3 slags on corundum/calcium hexaaluminate based castables

Due to the corrosion of CaO-Al2O3 based slags on refractory materials is related to the safe smelting of low-density and high-strength steel with high aluminum, the reaction experiment of calcium hexaaluminate castables with high-alumina and low-silicon CaO-Al2O3 based slag was carried out by introducing calcium hexaaluminate into corundum castables, and it was compared with that of alumina magnesia castable. The experimental results agreed with that of thermodynamic simulation and show that corundum calcium hexaaluminate castable has excellent slag resistance. Because the corundum calcium hexaaluminate castable reacted with the CaO Al2O3 based slag and produced high melting point phase CA2, which consumed a large amount of CaO in the slag and increased the viscosity of the slag, and CA2 filled the pores and blocked the penetration of slag. The wear mechanism of the calcium hexaaluminate castable is slag infiltration due to the higher porosity. Therefore, the combination of corundum aggregates and calcium hexaaluminate matrix is expected to be a candidate refractory material for ladle lining of low density and high strength steel smelting.     

Change of cleanliness of IF steel refined by RH with oval submerged tube

Based on continuous sampling after Al deoxidation during RH refining, the change of cleanliness of molten steel with oval and circle submerged tubes respectively was studied. The results show that removal rate of inclusions with oval submerged tube is higher than that of the circle submerged tube. The main inclusions in steel after Al deoxidation are Al2O3 inclusions, which present different morphologies at different time. When the cycle time reaches 1min after Al deoxidation, the shape of Al2O3 inclusions is cluster and the size is over a few hundred microns??when the cycle time reaches 2 min, the type and shape of inclusions don??t change, but the size reduces to tens of microns; when the cycle time reaches 6 min, the type of inclusions don??t change, but the shape of inclusions is single and globular and the size is less 10??m. Besides, the number density of inclusions obviously decreases with the increase of cycle time and reaches to the lowest level in the case of 4min after Al deoxidation.     

高铝低硅CaO-Al2O3系熔渣对刚玉/六铝酸钙质浇注料的作用行为

摘要：由于高铝低硅CaO-Al2O3系熔渣对耐火材料的侵蚀损毁影响高铝含量低密度高强钢的安全冶炼生产,为此通过在刚玉质浇注料中引入六铝酸钙,开展六铝酸钙质浇注料与高铝低硅CaO-Al2O3系熔渣反应实验,并与铝镁浇注料进行对比研究了其作用行为。实验结果表明：刚玉 六铝酸钙浇注料具有优异抗渣性能。这主要是由于熔渣中大量的CaO被消耗,间接提高了熔渣黏度,并与刚玉 六铝酸钙浇注料反应生成的高熔点相CA2填充了气孔,阻挡了熔渣的渗透,实验结果与热力学模拟计算结果相吻合。六铝酸钙浇注料自身气孔率高,熔渣主要以渗透形式对六铝酸钙耐火材料造成破坏。因此,将刚玉骨料与六铝酸钙基质组合是有望成为低密度高强钢冶炼用钢包内衬候选耐火材料。     

20CrMnTi冶炼过程形成CaO(CaS)-Al2O3-MgO夹杂的分析

 FactSage对钙处理前后钢液的平衡计算以及典型夹杂物在CaO-CaS-Al2O3三元相图中演变规律的研究结果表明：钢中硫含量大于0.01%(质量分数,下同)时,难以得到理想的钙处理效果,主要原因在于钙处理过程中钙主要与硫结合生成CaS夹杂,同时少部分钙将对Al2O3进行变性;钙处理过程中CaO(CaS)-Al2O3演变规律为Al2O3→Al2O3+CaO·6Al2O3+CaS→CaO·2Al2O3+CaS(CaO含量较少)→Al2O3·CaO+CaS(CaO含量较多)。通过对复合夹杂物电镜面分布扫描结果的描边处理能够有效辨别复合夹杂物的成分,发现典型CaO(CaS)-Al2O3-MgO夹杂物成分为xCaO·yAl2O3+xMgO·yAl2O3+Al2O3+CaS,并据此提出了一种新的评价钙处理效果的方法。     

铝土矿低钙石灰烧结过程热力学分析

通过对CaO-Al2O3、CaO-Al2O3-SiO2、CaO-SiO2、Al2O3-SiO2系的热力学分析,探讨铝土矿低钙石灰烧结过程中的热力学反应规律。结果表明,在烧结温度范围内(1 200～1 400℃),生成CaO.Al2O3和2CaO.Al2O3.SiO2的反应能发生,Al2O3可与SiO2生成Al2O3.SiO2。     

RH精炼工艺对无取向硅钢MgO·Al2O3夹杂物演变影响及控制

 基于BOF→RH→CSP生产工艺,研究了RH精炼过程钢中夹杂物类型演变及MgO?Al2O3夹杂物形成规律,同时对MgO?Al2O3夹杂物的形成条件进行了热力学计算,借助CFD数值模拟软件研究了RH精炼过程卷渣行为。研究发现,RH精炼过程20和30 min时,[w([MgO])/w([Al2O3])]为0.005～0.020,未发现MgO?Al2O3夹杂物;RH出站后夹杂物[w([MgO])/w([Al2O3])]为0.3～0.5,且RH精炼结束后MgO?Al2O3夹杂物占夹杂物总量的58.4%;另外,RH精炼过程钢液表面速度CFD模拟结果为0.57 m/s,大于临界卷渣速度0.45 m/s,且顶渣成分与夹杂物成分相近,存在卷渣现象。热力学计算表明,钢液与炉渣平衡时钢中[w([Al])]为0.31%～0.37%,[w([Mg])]为0.000 24%～0.000 28%,在MgO?Al2O3生成区域之内。减少RH处理过程卷渣,浇铸过程下渣及控制顶渣和包衬相中MgO质量分数可抑制MgO?Al2O3夹杂物形成。     

Effect of Oxygen Partial Pressure on Phase Equilibria and Liquidus in CaO-Al2O3-FeOx System

 A high temperature equilibration experiment was carried out to investigate the effect of oxygen partial pressure on the phase equilibria and liquidus in CaO-Al2O3-FeOx system with the intermediate oxygen partial pressures of 10.13 Pa and 1.01×10-3 Pa. The equilibrated phases and their compositions of the quenched samples were analyzed by using SEM/EPMA (Scanning Electron Microscope/Electron Probe Micro-Analysis) and XRD (X-Ray Diffraction). The phase equilibrium results include two cases, the two-phase coexistence and the three-phase coexistence in the high Al2O3 region with oxygen partial pressure of either 10.13 Pa or 1.01×10-3 Pa. Effects of oxygen partial pressure and temperature on the liquidus along the primary phase fields of CaO·Al2O3 and CaO·2Al2O3 were notable. With the decrease of oxygen partial pressure, the liquid area expands and the liquidus of CaO·Al2O3 and CaO·2Al2O3 primary fields moves to the Al2O3-FeOx region. On the other hand, the liquid area of CaO-Al2O3-FeOx system extends extremely to the high Al2O3 region with the temperature increasing from 1400 to 1500 ℃, especially at lower oxygen partial pressure. The present experiment results are in good agreement with the calculated ones by FactSage.