基于两温两密度法的FeO-Fe2O3-SiO2三元渣系成分软测量模型

针对火法冶炼熔渣成分含量与其物理性质强耦合的特点,以渣系温度和密度为软测量辅助变量,采用泰勒级数三次展开回归算法,建立基于两温两密度法的三元渣系成分软测量数学模型. FeO-Fe2O3-SiO2渣系的实例验证表明,回归计算精度高,平均相对误差（绝对值）仅为0.412%,多组软测量预测命中率高,且渣系组分含量适应范围较宽.依此模型计算绘制的密度-温度特性曲线分析表明,该模型能较好地反映三元渣系密度与组分含量、温度间的内在规律,为实现三元渣系组分含量预测提供了良好的软测量模型.     

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.     

Distribution equilibria of Pb and Cu between CaO-SiO2-Al2O3 melts and liquid copper

The distribution equilibria of lead and copper between CaO-SiO₂-Al₂O₃ melts and liquid copper were measured at 1623 K under a controlled H₂-CO₂ atmosphere. The distribution ratios were plotted against the oxygen partial pressure, and reasonable oxide forms dissolved in the melts were estimated from the slopes of the plots. The activity coefficients of lead oxide (PbO) and cuprous oxide (CuO_0.5) increased with increasing slag basicity, defined by X _CaO/X _SiO2. The temperature dependence of the activity coefficients of lead oxide and cuprous oxide was also measured.     

Activities in MnO-SiO2-AI2O3 slags and deoxidation equilibria of Mn and Si

The activities of MnO and SiO₂ along the liquidus line in the MnO-SiO₂-Al₂O₃-Fe_tO (1.2 to 6.7 mass pct) system were determined at 1823 and 1873 K by using a slag-metal equilibration technique. On the basis of the re-evaluated MnO iso-activity curves, the SiO₂ and Al₂O₃ iso-activity curves were determined by using the ternary Gibbs-Duhem relation. The control of inclusions composition in Si-Mn killed steels is discussed based on the equilibria between inclusion and steel with respect to Si, Mn, Al, and O.     

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.     

Embrittlement of some metallic glasses by Sb,Se, and Te

Some metallic glasses have been found to embrittle after annealing at low temperatures, much as do some steels. In phosphorus-bearing alloys, phosphorus has been found to segregate during annealing and result in sample embrittlement. The present report describes the effects of the steel-embrittling elements Sb, Se, and Te on metallic glasses in which the primary metallic constituents are Fe and/or Ni. Bend ductility and stress relaxation measurements of as-cast and annealed glassy alloy ribbons have been used to study embrittlement resulting from less than 0.2 at.% Sb, Se, and Te addition to the base alloys. XRD, DSC, and magnetic measurements have been used to further characterize the samples and to check for changes in magnetic properties which may accompany embrittlement. Results show that P is a very weak embrittler compared with Sb, Se, and Te. Furthermore, the embrittling power of these three elements varies in the sequence Te ⩾ Se ⪢ Sb, the same sequence as found in steels. The effect of a given embrittler is enhanced when substituting Fe in place of Ni. No substantial changes in DSC or magnetic measurements have been found as a result of substituting the small amount of embrittler into the base alloys investigated.     

Distribution of Boron Between Silicon and CaO-MgO-Al2O3-SiO2 Slags

Production of solar-grade silicon through metallurgical refining methods can be less expensive than current production methods both in terms of energy use and capital cost. Slag refining is a potential metallurgical refining method for removal of boron from silicon. The distribution of boron between silicon and binary CaO-SiO₂ and MgO-SiO₂ slags, and between silicon and ternary CaO-MgO-SiO₂ and CaO-Al₂O₃-SiO₂ slags has been investigated in this work at 1873 K (1600 °C). The distribution coefficient of boron has been found to be between 2 and 2.5 in the binary CaO-SiO₂ and MgO-SiO₂ systems. It has also been found to be in the same range across the entire CaO-MgO-SiO₂ system. In these systems the distribution coefficient is unaffected by slag composition. The distribution coefficient has been found to decrease with increasing Al₂O₃ content in the slag in the ternary CaO-Al₂O₃-SiO₂ system.     

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。     

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.     

Thermodynamics of copper matte converting: Part III. Steady-state volatilization of Au,Ag, Pb,Zn, Ni,Se, Te,Bi, Sb,and As from slag,matte, and metallic copper

A comprehensive compilation of various thermodynamic data required for a complete analysis of copper matte converting reactions is presented. The data comprise estimated free energies of formation for such gases as SeO, SeS, TeO, TeS, BiO, BiS, SbO, SbS, AsO, and AsS, as well as activity coefficients in dilute copper alloys and vapor pressures of various elements and compounds. The volatilization of minor elements in steady-state reactors comprising gas and several condensed phases is mathematically formulated, and a parameter which governs the volatilization in such reactors is defined and named volatilization constant. The vapor pressures of various volatile species are calculated thermodynamically for the Noranda Process reactor by assuming equilibrium conditions. The volatilization constants of various minor elements are expressed explicitly as functions of oxygen and sulfur activities. Formerly Associate Professor, Department of Metal-lurgical Engineering, University of Utah, Salt Lake City, UT.     

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.     

顶渣成分对夹杂物塑性化的影响

首先采用Fact Sage热力学软件对Ca O-Al2O3-Si O2-Mg O(10%)系夹杂物的塑性化控制进行了讨论,并进行了顶渣成分对夹杂物成分影响的实验室和工业试验研究。研究表明:在Ca O-Al2O3-Si O2-Mg O(10%)相图中,当w(Ca O)=8%~48%,w(Si O2)=35%~75%,w(Al2O3)=0~32%时,夹杂物处于塑性区域。随着顶渣中Al2O3含量的升高,帘线钢夹杂物中的Al2O3含量也随之升高,且夹杂物的分布也随顶渣中w(Al2O3)的升高而变得分散。综合实验室试验研究和工业试验生产结果,通过调节顶渣的成分,将顶渣碱度控制在0.7~0.9,w(Al2O3)=2%~5%时,可控制钢中非金属夹杂物的塑性化,断丝率降低了30%,达到了提高盘条质量的目的。     

Distribution of cobalt between liquid copper and copper silicate slag at 1523 K

The solubility of cobalt in Cu₂O-SiO₂ slags held in silica crucibles and equilibrated with copper-cobalt alloys has been investigated for conditions of varying amounts of cobalt in the alloy charged at a temperature of 1523 K. The solution of cobalt in slag from its alloy is explained by the equation: Co (in alloy) + Cu₂O (in slag) = 2 Cu (in alloy) + CoO (in slag) The average distribution ratio, valid from 0.04 to 0.10 pct Co in the equilibrated metal, is: (Pct Co in slag)/(Pct Co in metal) = 400 ± 50 The results are explained with the help of SEM, X-ray diffraction and EDAX, which indicated that the phase assemblages encountered as charged cobalt is increased are: SiO₂ + melt; Co₂SiO₄ + melt and CoO + Co₂SiO₂ + melt. In the last case, a coherent layer of cobalt silicate was found to have formed on the crucible surface. A tentative phase diagram of the ternary Cu₂O-CoO-SiO₂ system is presented. A change in the equation giving the activity coefficient of cobalt in Co-Cu alloys is suggested to bring calculated activity in agreement with the presence of CoO found experimentally as a separate phase. Ramana G. Reddy, formerly at The University of Utah     

炉渣组分对CaO-Al2O3-SiO2-TiO2-MgO-Na2O渣系与铁液间硫分配比的影响

针对高碱度高氧化铝的CaO-Al2O3-SiO2-TiO2-MgO-Na2O六元渣系,通过在1 773 K温度下测定其与铁液间的硫分配比,研究该渣系的脱硫性能.利用偏最小二乘法回归分析,建立了可较好预测硫分配比的回归方程,利用回归方程分析了炉渣碱度(mCao/msiO2)、MgO、TiO2、Al2O3以及Na2O对硫分配比的影响.结果表明,当炉渣碱度大于2.9时,炉渣硫分配比均在140以上,表明该渣系具有较强的脱硫能力.在实验范围内,硫分配比随炉渣碱度的增加而提高.当碱度一定时,MgO对硫分配比的影响不大,TiO2、Al2O3均使硫分配比降低,其中Al2O3降低硫分配比较为明显.硫分配比随Na2O增加而增加,少量的Na2O即可明显提高炉渣的脱硫能力.     

Aspects of smelting reduction of chromite ore fines in CaO-FeO-Cr2O3-SiO2-Al2O3 slag system by carbon dissolved in high carbon ferrochromium alloy bath

Abstract

Chromite reduction by carbon dissolved in a high carbon ferrochromium alloy melt has been investigated in the temperature range 1580-1640°C using a slag system based on CaO₂-FeO-Cr₂O₃-SiO₂-Al₂O₃. Although the reduction is essentially first order with respect to Cr₂O₃ concentration, it exhibits both zero order and first order reaction kinetics. The zero order period is occupied by the preferential reduction of iron oxide, during which time there is no significant change in the concentration of Cr₂O₃. The predominance of the divalent chromium oxide in the slag phase is seen to provide further evidence that the reduction of chromite occurs by a stagewise process, involving the thermodynamically stable CrO species. While high basicity slags may be recommended to minimise the generation of CrO, and hence improve reaction kinetics and the extent of Cr₂O₃ reduction, there is a limitation imposed by chemical erosion of the alumina crucible as the slag basicity is increased above unity, with the dissolving Al₂O₃ further retarding the reduction kinetics. There is also evidence to suggest the participation of a reductant other than carbon (possibly silicon) in the reduction of chromite.     

Thermodynamics of nitrogen in CaO-SiO2-AI2O3 slags and its reaction with Fe-Csat. melts

The solubility of nitrogen as the nitride ion in CaO-SiO₂-Al₂O₃ slags in equilibrium with N₂-CO gas mixtures and carbon was measured at 1823 K. The nitride capacity (C _N3-) was calculated to compare the nitrogen contents measured under different nitrogen and oxygen potentials.C _N3- decreased with increasing basicity and by replacing SiO₂ with A1₂O₃. The nitrogen partition ratio between carbon saturated iron and the slag was measured in CO gas at one atmosphere at 1823 K. By comparing the partition ratios with the corresponding nitride capacities measured by the gas-slag experiments, it was concluded that the oxygen partial pressure at the slag-metal interface was controlled by the Fe-FeO reaction. A new definition of nitride capacity was proposed based on the reaction between nitrogen and the network former,i.e., SiO₂ or A1₂O₃. This capacity could consistently explain the experimental results. Empirical equations were derived to estimate the activity coefficients of silicon and aluminum nitrides in the slags. On leave of absence from the Research Institute of Mineral Dressing and Metallurgy, Tohoku University, Sendai, Japan.     

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。