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1 530 ℃下CaO-Al     

Viscosity and Structure Changes of CaO-SiO2-Al2 O3-CaF2 Melts with Substituting Al2 O3 for SiO2

During the smelting process of the high Al steels,the reaction between SiO_2 in molten slag and dissolved aluminum in liquid steel always takes place.This aluminathermic reduction reaction will lead to the substitution of 1mol SiO_2 for 2/3mol Al_2O_3.Therefore,the investigations about the influence of the ratio of Al_2O_3 to SiO_2on viscosity and structure changes of mould flux during this process are very necessary.The viscosity variation of CaO-SiO_2-Al_2O_3-CaFv2 melts was studied by changing compositions considering the aluminathermic reduction reaction.It was found that viscosity increased monotonously with gradually increasing the substitution extent.According to the Raman analysis,the substitution of Al_2O_3 for SiO_2 leads to the decrease of non-bridging oxygen but the increase of bridging oxygen.Therefore,degree of polymerization and viscosity increase as the substitution extent increases.By comparing the measured viscosities with the model calculated values,it was found that both the recently developed Zhang′s model and Roboud model could describe the viscosity variation behavior of CaO-SiO_2-Al_2O_3-CaF_2 melts very well.     

Experimental study of phase equilibria in the PbO-Al2O3-SiO2 system

Equilibrium phase relations in the PbO-Al₂O₃-SiO₂ system have been investigated experimentally by means of high-temperature equilibration, quenching, and electron probe X-ray microanalysis (EPMA). The system has 21 primary phase fields including three monoxides (PbO, Al₂O₃, and SiO₂), seven binary compounds (Al₆Si₂O₁₃, PbAl₂O₄, PbAl₁₂O₁₉, Pb₂Al₂O₅, PbSiO₃, Pb₂SiO₄, and Pb₄SiO₆), and eleven ternary compounds (PbAl₂Si₂O₈, Pb₃Al₁₀SiO₂₀, Pb₄Al₂Si₂O₁₁, Pb₄Al₄SiO₁₂, Pb₄Al₄Si₃O₁₆, Pb₄Al₄Si₅O₂₀, Pb₅Al₂Si₁₀O₂₈, Pb₆Al₂Si₆O₂₁, Pb₈Al₂Si₄O₁₉, Pb₁₂Al₂Si₁₇O₄₉, and Pb₁₂Al₂Si₂₀O₅₅). Three new ternary compounds, Pb₄Al₄SiO₁₂, Pb₄Al₄Si₅O₂₀, and Pb₁₂Al₂Si₁₇O₄₉, were observed and characterized by EPMA. No extensive solid solution in any of the compounds was found in the present study. The liquidus isotherms were experimentally determined in most of the primary phase fields in the temperature range from 923 to 1873 K, and the ternary phase diagram of the PbO-Al₂O₃-SiO₂ system has been constructed.     

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。     

Critical evaluation and optimization of the thermodynamic properties and phase diagrams of the CaO-Al2O3, Al2O3-SiO2, and CaO-Al2O3-SiO2 systems

All available thermodynamic and phase diagram data have been critically assessed for all phases in the CaO-Al₂O₃, Al₂O₃-SiO₂, and CaO-Al₂O₃-SiO₂ systems at 1 bar pressure from 298 K to above the liquidus temperatures. All reliable data for the binary systems have been simultaneously optimized to obtain, for each system, one set of model equations for the Gibbs energy of the liquid slag and all solid phases as functions of composition and temperature. The modified quasichemical model was used for the slag. With these binary parameters and those from the optimization of the CaO-SiO₂ system reported previously, the quasichemical model was used to predict the thermodynamic properties of the ternary slag. Two additional small ternary parameters were required to reproduce the ternary phase diagram and ternary activity data to within experimental error limits. The calculated optimized phase diagram and thermodynamic properties are self-consistent and are the most reliable currently available estimates of the true values.     

Cr2O3微粉加入量对Al2O3-SiO2浇注料性能的影响

以特级高铝矾土和棕刚玉为主要原料、纯铝酸钙水泥(Secar 71)为结合剂的Al2O3-SiO2浇注料为研究对象,研究了Cr2O3微粉加入量对其施工性能、强度以及抗渣性能的影响,结果表明:加入一定量的Cr2O3微粉后,浇注料的抗渣性能得到明显改善;并随着Cr2O3微粉加入量的增加,浇注料的强度逐渐增大;对浇注料施工性能影响不大.     

Interactions in the Al2O3-ZrO2-Y2O3 system

The phase diagram of the Al₂O₃-ZrO₂ system was replotted over a broad range of concentrations (0–100 mole %) and temperatures (1150–2800°C). The polymorphic transformation of zirconium F ? T occurs via the metatectic reaction F ? T + L at 2260°C. Phase triangulation was employed to plot the diagrams of the partially quasibinary sections in the Al₂O₃-ZrO₂-Y₂O₃ system. Since there is a wide solubility range based on ZrO₂ in the binary ZrO₂-Y₂O₃ system, the triangulation conodes are displaced in the F-solid solution corners. The two-phase regions Y₃A₅-F are quite broad. The reactions in all three are of the eutectic type. The ternary solid solution fields in the Al₂O₃-ZrO₂-Y₂O₃ system had no observable width.     

Modeling of viscosities of the partly crystallized slags in the Al2O3-CaO-“FeO”-SiO2 system

A viscosity model of the partly crystallized slag in the Al₂O₃-CaO-‘FeO’-SiO₂ system has been developed in conjunction with the thermodynamic computer package F*A*C*T. Proportions of solids crystallized out of the liquid phase and compositions of the remaining liquid phase predicted by F*A*C*T are used in the viscosity model. Various heterogeneous viscosity models have been tested using large experimental dataset in the Al₂O₃-CaO-‘FeO’-SiO₂ system in reducing conditions close to the equilibrium with metallic iron. The Roscoe equation with new empirical parameters was found to provide reasonable agreement with experimental data. Examples of model application to industrial nonferrous smelting slag systems are presented. This model can also be applied to coal ash slags.     

不同酸碱性SiO_2微粉在铝硅系不定形耐火材料中的应用

为了研究化学性质不同的SiO2微粉在铝硅系不定形耐火材料中的应用,以焦宝石为主要原料,铝酸钙水泥为结合系统,分别研究了不同酸碱性的SiO2微粉对铝硅系不定形耐火材料性能的影响。试样自然干燥24h脱模后,再经110℃烘干24h,分别于600℃、800℃、1000℃和1300℃热处理3h。检测各温度热处理后含有不同酸碱性SiO2微粉试样的线变化率、体积密度、常温抗折强度、常温耐压强度、常温耐磨性能、热膨胀系数和抗热震性能。结果表明,在力学性能方面,铝硅系不定形耐火材料中引入酸性SiO2微粉的试样比引入弱碱性SiO2微粉的试样具有更大的体积密度,更高的常温抗折强度、常温耐压强度和更好的常温耐磨性能。在热学性能方面,铝硅系不定形耐火材料中引入弱碱性SiO2微粉的试样比引入酸性SiO2微粉的试样具有更低的热膨胀系数和更优良的抗热震性能。     

RE2O3-CaO-SiO2-CaF2-MgO-Al2O3系炉渣的凝固组织

为了综合利用富稀土高炉渣,利用扫描电镜观察并配合能谱分析和X射线衍射分析研究了RE2O3-CaO-SiO2-CaF2-MgO-Al2O3系炉渣于1 400 ℃熔化并保温30 min,再以1 ℃/min的冷却速度凝固后的组织.结果表明在凝固过程中,绝大部分稀土富集于铈钙硅石(RE2O3·CaO·SiO2)相中;熔渣的凝固组织主要由铈钙硅石、枪晶石(CaF2· 3CaO·2SiO2)、萤石(CaF2)和硫化钙(CaS)这4种相组成.     

Iron redox equilibria in CaO-Al2O3-SiO2 and MgO-CaO-Al2O3-SiO2 slags

Measurements have been made of the ratio of ferric to ferrous iron in CaO-Al₂O₃-SiO₂ and MgO-CaO-Al₂O₃-SiO₂ slags at oxygen activities ranging from equilibrium with pCO₂/pCO≈0.01 to as high as air at temperatures of 1573 to 1773 K. At 1773 K, values are given by $\begin{gathered} \log {\text{ }}\left( {\frac{{Fe^{3 + } }}{{Fe^{2 + } }}} \right) = 0.3( \pm {\text{ }}0.02){\text{ }}Y + {\text{ }}0.45( \pm {\text{ }}0.01){\text{ }}\log \hfill \\ \left( {\frac{{pCO_2 }}{{pCO}}} \right) - 1.24( \pm {\text{ }}0.01) \hfill \\ \end{gathered} $ where Y=(CaO+MgO)/SiO₂, for melts with the molar ratio of CaO/SiO₂=0.45 to 1.52, 10 to 15 mol pct Al₂O₃, up to 12 mol pct MgO (at CaO/SiO₂≈1.5), and with 3 to 10 wt pct total Fe. Available evidence suggests that, to a good approximation, these redox equilibria are independent of temperature when expressed with respect to pCO₂/pCO, probably from about 1573 to 1873 K. Limited studies have also been carried out on melts containing about 40 mol pct Al₂O₃, up to 12 mol pct MgO (at CaO/SiO₂≈1.5), and 3.6 to 4.7 wt pct Fe. These show a strongly nonideal behavior for the iron redox equilibrium, with $\frac{{Fe^{3 + } }}{{Fe^{2 + } }} \propto \left( {\frac{{pCO_2 }}{{pCO}}} \right)^{0.37} $ The nonideal behavior and the effects of basicity and Al₂O₃ concentration on the redox equilibria are discussed in terms of the charge balance model of alumino-silicates and the published structural information from Mössbauer and NMR (Nuclear Magnetic Resonance) spectroscopy of quenched melts.     

B2O3在CaO-BaO-SiO2-Al2O3-CaF2精炼渣中的作用

选择w（CaO）=46％,w（BaO）=10％,w（SiO2）=11．2％,w（Al2O3）=11．6％的渣作基础渣系,将B2q作助熔剂替代CaF2,发现B2q和CaF2的助熔效果相当,B2q可用作环保型助熔剂。将CaO-SiO2-BaO-Al2O3-CaF2作基础渣系,B2O3作酸性氧化物,在碱度（m（CaO＋BaO）／m（SiO2＋B2O3））为2．5和2．8时,研究B2O3替代SiO2后精炼渣的熔化性能。结果表明,B2O3替代25％的SiO2后就可大幅度降低粘度,并且发现富硼精炼渣的高温熔化性能稳定,粘度值稳定在0．3～0．5Pa·s。在碱度为2．8wt进行脱硫工艺实验,当w（SiO2）=20．6％时渣剂脱硫率为80％,当w（SiO2）=10．3％,w（B2O3）=10．3％时渣剂脱硫率为91．3％,主要原因是熔化性能良好的熔渣有助于提高传质速率。     

Effect of Al2O3 content in CaO-Al2O3-SiO2 slag on corrosion resistance of alumina magnesia castable

The toughness and erosion resistance of steel can be improved by adding an appropriate amount of aluminum. However it will increase the content of Al2O3 in slag and react with the existing alumina magnesia castable, and affect smelting and quality of steel. Therefore, static crucible method was applied, corrosion experiments of the CaO-Al2O3-SiO2 slags on the alumina magnesia castable were carried out, and the influence of Al2O3 content (w(CaO)∶w(Al2O3), C/A ratio) on slag corrosion resistance was investigated by combining thermodynamic simulation. The following conclusions were obtained: with the increase of Al2O3 content in the slags, the thicker isolation layer with high melting point is easier to form at the reaction interface between alumina magnesia castable and the slags. The direct dissolution of the refractory components into the slags can be changed to indirect dissolution, which is conducive to improving the corrosion resistance of alumina magnesia castable. Nevertheless, when the content of Al2O3 in the slag is about 32 wt.%, the slag corrosion is generally weak, when the content of Al2O3 in the slag is more than 36 wt.%, the slag has serious permeability to the alumina magnesia castable, which is easy to cause the deterioration and spalling of the material. It provides guidance on the optimization and design of the refractories for Al containing steel smelting.     

CaO-Al2O3-SiO2系渣中Al2O3含量对铝镁质浇注料侵蚀的影响

摘要：钢中添加适量铝元素可以提高其韧性与耐腐蚀性,但在冶炼过程中会影响炉渣中Al2O3含量而改变其与现行铝镁质浇注料的界面反应,制约钢种冶炼及品质提升。因此,采用静态坩埚法开展铝镁质浇注料的抗CaO-Al2O3-SiO2渣蚀实验,并结合热力学模拟计算探究Al2O3含量（w(CaO)∶w(Al2O3),C/A）变化对耐火材料渣蚀的影响规律,得到以下结论：随着熔渣中Al2O3含量的增加,铝镁质浇注料与熔渣反应界面越易形成更厚的高熔点隔离层,将耐火材料组分向熔渣中的直接溶解转变为间接溶解,有利于提升铝镁质浇注料的抗侵蚀性;当渣中的Al2O3质量分数在32%左右时,熔渣的侵蚀性总体较弱,但当渣中的Al2O3质量分数不小于36%时,熔渣对铝镁质浇注料产生了严重的渗透性,也易造成材料变质剥落。这为面向含铝钢冶炼用耐火材料的优化设计提供参考。     

Influences of Al2O3/CaO and Na2O/CaO Ratios on Viscosities of CaO-Al2O3-SiO2-Na2O Melts

The influences of Al₂O₃/CaO and Na₂O/CaO ratios on viscosities of CaO-Al₂O₃-SiO₂-Na₂O melts are investigated by the rotating cylinder method in this study. It is indicated from the experimental results that viscosity first increases and then decreases as gradually increasing Na₂O/CaO ratio. As increasing Na₂O/CaO ratio while keeping the contents of Al₂O₃ and SiO₂ constant, the transformation of bridging oxygen (from being bonded with Al³⁺ ion charge compensated by Ca²⁺ ion to that compensated by Na⁺ ion, for the higher priority of Na⁺ ion relative to Ca²⁺ ion) increases the viscosity, whereas the transformation of non-bridging oxygen decreases the viscosity. These two factors lead to the appearance of viscosity maximum. The viscosity model proposed in our previous papers could well describe the viscosity variation tendency.     

Thermodynamic study on the effect of CaF2 on the nitrogen and carbon solubility in the CaO-Al2O3-CaF2 slag system

The nitrogen and carbon solubilities in the CaO-Al₂O₃-CaF₂ slag system at 1723K were measured to understand the effect of CaF₂ on the nitrogen and carbon dissolution behaviour using thermochemical equilibration technique. The nitride capacity in the CaO_satd.-Al₂O₃-CaF₂ system was constant until X_Al2O₃ / X_CaF2 = 0.23, followed by decrease with an increase in X_Al2O₃ / X_CaF2 ratio, and then showed a constant value. The carbide capacity in the CaO_satd.-Al₂O₃-CaF₂ system also showed the similar behaviour to the nitride capacity, however, the effect of CaF₂ on the activity coefficient of nitride and carbide ions showed some differences in case of X_CaF2 = 0.2. The effect of CaF₂ on the activity coefficient of carbide and nitride ions would not be significant in case of CaO-rich region of X_CaO / X_CaF2 = 0.31. However, CaF₂ could be expected to affect the activity coefficient of each ion in case of the Al₂O₃-rich region, causing compensating effect of the incorporated nitride (carbide) mechanism. The relationship between nitride and carbide capacity was also discussed.     

用重选法去除锆刚玉中玻璃的试验研究

文章对用物理选矿去除锆刚玉中玻璃的方法进行了试验研究。含Na2O2．75％的锆刚玉经重选法去除玻璃后,Na2O含量可降至1．34％,其质量达到SJ-36锆刚玉砖的原料要求。     

Phase equilibrium studies in the “MnO”-Al2O3-SiO2 system

Phase relations and the liquidus surface in the system “MnO”-Al₂O₃-SiO₂ at manganese-rich alloy saturation have been investigated in the temperature range from 1373 to 1773 K. This system contains the primary-phase fields of tridymite and cristobalite (SiO₂); mullite (3Al₂O₃·2SiO₂); corundum (Al₂O₃); galaxite (MnO·Al₂O₃); manganosite (MnO); tephroite (2MnO·SiO₂); rhodonite (MnO·SiO₂); spessartine (3MnO·Al₂O₃·SiO₂); and the compound MnO·Al₂O₃·2SiO₂.     

����������La2O3-Al2O3-CaF2����������Ũ��ģ��

In order to accurately control the rare earth content in liquid steel in electroslag remelting (ESR) process, according to the ion and molecule coexistence theory (IMCT) of slag structure and corresponding phase diagrams, a thermodynamic calculating model for the evaluation of mass action concentrations (designated by Ni for structure unit i) for La2O3-Al2O3-CaF2 slag system was formulated. The results show that the calculated values of NLa2O3 are in good agreement with the reported measured values, indicating that this calculating model can wholly embody the characteristics of the slag system. The activity of La2O3 decreases with the increasing of the Al2O3 and CaF2 content, and Al2O3 is stronger than CaF2 in decreasing the activity of La2O3. But the activity of La2O3 increase with the increasing in temperature at the composition range of 30% La2O3, 20% Al2O3, 50% CaF2. Above all, the activity of La2O3 in La2O3-Al2O3-CaF2 slag system can be quantitatively analyzed by this thermodynamic model, and this model can provide a theoretical basis for precisely controlling the lanthanum content in molten steel in ESR process.