Phase diagram assessment of CaO–Al2O3–La2O3 system

Considering the significance of CaO–Al₂O₃–RE₂O₃ (RE?=?rare earth) phase diagrams, the Redlich–Kister expression was employed to evaluate the binary phase diagrams of CaO–Al₂O₃, La₂O₃–Al₂O₃ and CaO–La₂O₃ systems in the present work. Also, the activities of CaO and Al₂O₃ in the CaO–Al₂O₃ binary system were calculated. The phase diagram of the CaO–Al₂O₃–La₂O₃ ternary system was first assessed by Kohler extrapolation method. The accuracy of calculated phase diagrams was validated by comparing with existing experimental points and the calculation results from the literature. The obtained diagrams will lay a foundation for Al-killed steelmaking process, metallurgical flux and other fields’ industrial application.     

氟对CaO—CaF2—SiO2和CaO—CaF2—SiO2—FeOx玻璃硅酸盐网络体的影响

通过使用X射线光电子分光仪(XPS)和穆斯堡尔分光检测仪对CaO-SiO2-CaF2和CaO-SiO2-CaF2-FeOx两种玻璃质进行了检测，研究F的化学性能和加入F后对硅酸盐网络体聚合度的影响。Fls XPS衍射图表明，F易与C8结合而不是Si，从CaO-SiO2-CaF2玻璃体的Ols XPS衍射图和CaO-SiO2-CaF2-FeOx玻璃体的穆斯堡尔衍射图的Fe^2 与Fe^3 的比值分析表明，加入CaF2对两种玻璃硅酸盐网络体没有解聚作用。     

碱性氧化物对CaO—SiO2-CaF2玻璃结晶化的影响

在连铸坯初始凝固阶段,控制渣膜结晶度对于调节从铸坯到结晶器的水平热流至关重要。通过等温和加热2种条件研究了碱性氧化物对枪晶石（3CaO·2SiO2·CaF2）的形成影响,它是在CaO—SiO2-CaG—M2O玻璃相（M=Li,Na,K））中的初始结晶相。加入碱性氧化物可降低玻璃相转变温度和降低晶体长大的表观活化能,从而达到提高枪晶石结晶之目的。然而,如果过多地加入碱性氧化物（M2O）可阻止枪晶石的形成,因为可导致由M2O替代CaF2。     

固体CaO在3CaO·P2O5-2CaO·SiO2饱和熔渣中的溶解及反应机理

摘要：为了深入了解非均相脱磷剂中固体CaO在3CaO·P2O5-2CaO·SiO2（C2S-C3P）饱和熔渣中的溶解及反应机理，采用静态浸入法和旋转圆柱法研究固体CaO在C2S-C3P饱和CaO-SiO2-FetO-P2O5（10%）渣中的溶解行为，运用FESEM/BSED EDS对固体CaO和熔渣界面进行了观察，分析了固体CaO与C2S-C3P饱和熔渣间的反应机理。结果表明，加强对熔池的搅拌，能够加快固体CaO在熔渣中的侵蚀速度和溶解速度；发现了固体CaO在饱和熔渣中的溶解数量受熔渣中FeO通过边界层向固体内部渗透深度的影响，FeO渗透深度越深，溶解越多；固体CaO先与熔渣中的硅和磷反应生成磷含量低的C2S-C3P固溶体，待一段时间后，最终生成磷含量高的Ca5(PO4)2SiO4。     

Formation and Evolution Mechanism of the Inclusions of Al2O3·SiO2·CaO and Al2O3·SiO2·CaO·MgO in Seamless Steel Tube Steel

Herein, the formation and evolution mechanism of inclusions of Al₂O₃·SiO₂·CaO and Al₂O₃·SiO₂·CaO·MgO in seamless steel tube steel are investigated. In the long strip defects on the longitudinal cross section of the steel tube after the rolling bar piercing, the defect is mainly formed by Al₂O₃·SiO₂·CaO·MgO inclusions and Al₂O₃·SiO₂·CaO·inclusions dotted with·CaS inclusions after the rolling. The typical inclusions in the different steelmaking stages are mainly composed of CaS, Al₂O₃·(SiO₂), CaO·(SiO₂), MnS·(TiN), Al₂O₃·SiO₂·CaO·(CaS)·(MnS), Al₂O₃·SiO₂·CaO·MgO·(MnO), Al₂O₃·SiO₂·CaO·MgO·(CaS)·(MnS), etc. In the billet, the average sizes of Al₂O₃·SiO₂·CaO-based and Al₂O₃·SiO₂·CaO·MgO-based inclusions are much larger than those of the other types of inclusions. Part of SiO₂ in the deoxidized products SiO₂ can be reduced by [Al], resulting in the formation of the Al₂O₃·SiO₂ composite inclusions. The SiO₂ in Al₂O₃·SiO₂ inclusions can continuously be reduced by the dissolved [Ca] to form the Al₂O₃·SiO₂·CaO composite inclusions. The SiO₂ in the Al₂O₃·SiO₂·CaO inclusions can be reduced by the dissolved [Mg] to form the Al₂O₃·SiO₂·CaO·MgO composite inclusions. Another formation process of Al₂O₃·SiO₂·CaO·MgO inclusions is the entrapment of ladle slag in the vacuum degassing (VD) stage, due to the strong agitation of the rising Ar bubbles in the vacuum condition of the VD stage.     

Al2O3对CaO—“FeO”—SiO2—CaF2熔渣粘度的影响

在1714K－1757K温度范围内利用旋转圆柱法测试了CaO-“FeO”-SiO2-CaF2渣系粘度随着不同的Al2O3添加量的变化。第一步试验是对添加少量Al2O3达到平衡条件下进行的粘度测试。为了比较该结果采用一种工业用结晶器保护渣进行了类似的试验。对于这两种情况，发现在所有实验温度下粘度均随着Al2O3添加量的增加而增加，且增加的粘度与添加的Al2O3呈线性关系。对于工业用结晶器保护渣，添加2－6％Al2O3甚至会导致粘度大幅增加。采用上述系列熔渣在动态模型中也进行了等温试验。这里，熔渣粘度的变化用来监测连续不断地溶解在渣中的一种Al2O3圆盘与时间的函数关系。这样设计试验是为了溶解铝主要沿着垂直方向进行，按照试验后熔渣外形和粘度变化的速率讨论了Al2O3溶解的速率。Al2O3圆盘试验显示了渣的组分在固态Al2O3中的扩散及Al2O3的溶解是由熔渣中的固体物溶解产生的。     

用MgO饱和的CaO—SiO2-CaF2-Na2O炉渣对铁水脱硫

本文通过考虑将MgO作为重要的耐火材料组元,研究了1623K和1723K时,CaF：和Na：O对CaO—SiO2-CaF2-MgO饱和（-Na20）炉渣体系铁水脱硫的硫容量影响。MgO-饱和的炉渣体系液相线与CaO—SiO：-CaF2三元炉渣体系相类似,2CaO·SiO2-饱和的硅含量随Mg0饱和略微降低。尽管在MgO-饱和的硫化物容量低于CaO饱和-Si02-CaF2炉渣体系,但是大于有2CaO·SiO2相饱和的三元炉渣体系。这说明在CaO活度相对较低的条件下,MgO能增加自由O。的活度,在接近3CaO·SiO2-饱和组成,MgO降低了炉渣的硫化物容量,因为在高碱性组元中,Mg0的碱性低于CaO。除此之外,增加5％NaO可明显增加MgO-饱和炉渣的硫化物容量,特别在低‘CaO＋CaF：’组成时。这说明为了保持1623K时0．01的硫化物容量,‘CaO2＋CaF2’的投入数量从95％减少到75％,其对考虑铁水脱硫工艺中,降低用MgO饱和CaO和CaF2的消耗非常重要。     

Thermodynamic activity of the liquid-phase components in the CaO · SiO2-CaO · Al2O3 · 2SiO2-CaO · TiO2 · SiO2 system with four-phase invariant equilibrium

The CaO · SiO₂-CaO · Al₂O₃ · 2SiO₂-CaO · TiO₂ · SiO₂ system is analyzed. Thermodynamic analysis of monovariant and invariant solidification shows that, for invariant equilibrium and for solidification along the boundary curve between the solidification fields of anorthite and sphene, peritectic processes are observed. The invariant-state parameters of the system are determined: t = 1513 K; a _CaO = 0.0407; $a_{SiO_2 } = 0.5268$ ; $a_{Al_2 O_3 } = 0.00003$ , $a_{TiO_2 } = 0.005$ ). A corrected phase diagram is presented.     

CaO—CaF2—SiO2渣系碳酸盐容量和硫化物容量的关系

根据文献报道１４７３－１７７３Ｋ的ＣａＯ－ＣａＦ２－ＳｉＯ２渣系碳酸盐容量和１４７３－１６２３Ｋ硫化物容量的数值，考查了ＸＣａＯ、ＸＣａＯ／ＸＳｉＯ２、ＸＣａＯ／（ＸＳｉＯ２＋ＸＣａＦ２）、（ＸＣａＯ＋ＸＣａＦ２）／ＸＳｉＯ２及光学碱度五种表达炉渣成分的参数与碳酸盐和硫化物容量的关系，研究了该渣系碳酸盐容理和硫化物容量的关系，结果表明：碳酸盐容量与ＸＣａＯ／ＸＳｉＯ２，（ＸＣａＯ＋ＸＣａＦ２）／Ｘ     

CAS-OB refining: slag modification with B2O3–CaO and CaF2–CaO

Abstract

Evaluation of CAS-OB refining slags showed that the melting temperature and viscosity were very high and could further increase during the CAS-OB refining process, causing excessive slag to stick to the snorkel with resulting operational problems. To avoid this, B₂O₃–CaO (mass ratio 1 : 1) and CaF₂–CaO (mass ratio 1 : 1) were employed as modifiers added to the slag. The fusibility (melting temperature and viscosity) and desulphurising capacity of modified slag were investigated. Both B₂O₃–CaO and CaF₂–CaO can effectively lower the melting temperature and viscosity of slag. The results of experiments on sulphur partition equilibrium between metal and slag indicate that the sulphur content of metal can be further decreased by the modified slag.     

CaO—Al2O3—CaF2—SiO2—MgO五元精炼渣系的起泡性能

采用二次回归正交试验方法测定了１５３０℃下ＣａＯ－Ａｌ２Ｏ３－ＣａＦ２－ＳｉＯ２－ＭｇＯ五元精炼渣系的起泡性能。得出炉渣起泡指数与炉渣光学碱度、渣中Ａｌ２Ｏ３及ＣａＦ２含量间的回归方程。结果表明：炉渣的光学碱度和ＣａＦ２含量对起泡指数有较大影响,而Ａｌ２Ｏ３含量对起泡指数影响很小。具有最佳发泡性能的炉渣成分中ＣａＯ,Ａｌ２Ｏ３,ＣａＦ２,ＳｉＯ２,ＭｇＯ的质量分数分别为：４４．０６％,３０．００％,７．００％,８．９４％,１０％。研究结果还表明：炉渣起泡指数与炉渣粘度成正比,而与表面张力和密度的平方根成反比。     

转炉渣中CaO和CaF2的分析

利用氧化钙易溶解于稀醋酸,而氟化钙不溶解于稀醋酸的特性.试样以稀醋酸处理,用滤纸过滤不溶解物残渣,滤液加氢氧化钾溶液调节pH≥12.5,用EGTA滴定法测定CaO含量.过滤的不溶解物残渣在铂金坩埚中灰化、灼烧,加含有硼酸钠的混合熔剂,于950℃左右熔融、酸化浸取定容、分液后,加氢氧化钾溶液调节pH≥12.5,用EGTA滴定法测定CaF2含量.     

转炉渣中CaO和CaF2的分析方法

利用CaO易溶解于稀醋酸,而CaF2不溶解于稀醋酸的特性,以稀醋酸处理试样,用滤纸过滤不溶解物残渣,滤液加氢氧化钾溶液调节pH值不小于12.5,用EGTA滴定法测定CaO含量。过滤的不溶解物残渣在铂金坩埚中灰化、灼烧,加含有硼酸钠的混合熔剂,于950℃左右熔融、酸化浸取定容、分液后,加氢氧化钾溶液调节pH值不小于12.5,用EGTA滴定法测定CaF2含量。方法具有重复性好、精密度理想等特点。测定结果表明：CaO相对标准偏差小于0.1917%～0.4061%,CaF2相对标准偏差小于0.7407%～2.6514%。     

铁水预处理温度下CaO—SiO2—FeO—P2O5—CaF2渣系中CaO饱和溶解量

对１３００℃和１３５０℃的铁水预处理温度下ＣａＯ－ＳｉＯ２－ＦｅＯ－Ｐ２Ｏ５－ＣａＦ２渣系中ＣａＯ饱和溶解量进行了测定。实验结果表明，温度升高对提高ＣａＯ饱和溶解量有利，渣中ＣａＦ２，ＦｅＯ含量增加，ＣａＯ饱和溶解减少，当渣组成们于ＣａＯ＋Ｌ和Ｌ交界上时，与其它区域相比，ＣａＯ达到饱和所需溶解时间最短。     

CaO—Al2O3—CaF2—SiO2—MgO精炼渣系起泡性能与炉渣物理性质的关系

通过实验研究测定了ＣａＯ－Ａｌ２Ｏ３－ＣａＦ２－ＳｉＯ２－ＭｇＯ钢包精炼渣系的起泡性能,并在对该精炼渣系物理性质进行预测的基础上,利用无因次分析方法,得出了炉渣起泡指数与炉渣粘度、表面张力、密度的关系式。     

固体CaO在3CaO·P_2O_5-2CaO·SiO_2饱和熔渣中的溶解及反应机理

为了深入了解非均相脱磷剂中固体CaO在3CaO·P_2O_5-2CaO·SiO_2(C_2S-C_3P)饱和熔渣中的溶解及反应机理,采用静态浸入法和旋转圆柱法研究固体CaO在C_2S-C_3P饱和CaO-SiO_2-Fe_tO-P_2O_5(10%)渣中的溶解行为,运用FESEM/BSED-EDS对固体CaO和熔渣界面进行了观察,分析了固体CaO与C_2S-C_3P饱和熔渣间的反应机理。结果表明,加强对熔池的搅拌,能够加快固体CaO在熔渣中的侵蚀速度和溶解速度;发现了固体CaO在饱和熔渣中的溶解数量受熔渣中FeO通过边界层向固体内部渗透深度的影响,FeO渗透深度越深,溶解越多;固体CaO先与熔渣中的硅和磷反应生成磷含量低的C_2S-C_3P固溶体,待一段时间后,最终生成磷含量高的Ca_5(PO_4)_2SiO_4。