Mixed Alkali Effect in Viscosity of CaO-SiO2-Al2O3-R2O melts

Metallurgical and Materials Transactions B - The mixed alkali effects of Li2O, Na2O, and K2O on viscosity of CaO-SiO2-Al2O3 melts are investigated by rotating cylinder method. It is found that the...     

Activities in CaO-SiO2-Al2O3 slags and deoxidation equilibria of Si and Al

By using the data in previous and present slag-metal equilibrium experiments, the activities of SiO₂ along the liquidus lines in CaO-SiO₂-Al₂O₃ slags were determined at 1823 and 1873 K from the reaction Si+2O=SiO₂ (s), in which the oxygen activities were estimated from the measured oxygen contents or from the combination of nitrogen distribution ratios (L _N) and nitride capacities (C _N). The activities of Al₂O₃ were also determined from the reaction 2Al+3O=Al₂O₃ (s), in which the oxygen activities were estimated from the values for L _N and C _N, or from the reaction 3SiO₂ (s)+4Al=2Al₂O₃ (s)+3Si, in which the activities of SiO₂ and the contents of Al and Si along with the respective interaction coefficients were used. The activities of Al₂O₃ and CaO in the entire liquid region were estimated from the Rein and Chipman’s activities of SiO₂ by using the method of Schuhmann. On the basis of these activities, the deoxidation equilibria of Si and Al in steels were discussed.     

Photon conductivity of metallurgical slags of the three component system CaO-SiO2-Al2O3

The measuring method proposed by Keene and Quinn has been further developed to investigate 3-component slags of the system CaO-SiO₂-Al₂O₃ at temperatures of 800–1600°C in the wavelength range of 550 to 850 nm. The results are presented with the aid of the complex refraction index, which embodies all information on the optical properties of the slags investigated, including photon conductivity and thermal emissivity. Comparison of the photon conductivities determined shows good agreement with the corresponding values of various types of glass cited in literature. The discontinuous pattern of the phonon conductivity curve in the melting range of 40% CaO-40% SiO₂-20% Al₂O₃ slag, as already found by Gammal and Li, is also evident from the data of the present investigation.     

The sulphide capacity of CaO-SiO2-Al2O3-MgO(-FeO) smelting reduction slags

The effects of MgO and FeO contents on the sulphide capacity of Corex slags were investigated at 1773 K using gas/slag equilibrium technique as a fundamental study for stabilising Corex operational conditions. The gradual substitution of MgO for CaO at a fixed basicity [B = {(%CaO)+(%MgO)}/(%SiO₂)] decreased the sulphide capacities of CaO-SiO₂-Al₂C₃-MgO slags. The addition of FeO into the CaO-SiO₂-Al₂O₃-MgO slags at the fixed (%CaO)/(%SiO₂) ratio, MgO and Al₂O₃ contents significantly increased the sulphide capacities. The sulphide capacity decreased according to the increasing Al₂O₃ content at the fixed (%CaO)/(%SiO₂) ratio, MgO and FeO content. Based on the previously reported and present values of sulphide capacities, the sulphide capacity as a function of slag composition on the mole fraction base at 1773 K was expressed by the formula of log C_S = X_CaO – 3.89 X_SiO2 – 3.18 X_Al2O₃ – 0.55 X_MgO + 2.43 X_FeO – 2.61. In addition, the relationship between the sulphide capacity and optical basicity could be represented as the formula of log C_S = 12.51 A – 12.24 and the theoretical optical basicity of FeO was found be 0.94 from the correlation. The effect of FeO on the sulphur distribution ratio was estimated using the present sulphide capacity values and the oxygen activity in liquid iron, which could be determined with the help of Fe/FeO equilibrium. FeO activity in slag was well described by the quadratic formalism based on the regular solution model. The sulphur distribution ratio according to FeO content varies in an opposite way, compared with that of the sulphide capacity.     

Zur Struktur geschmolzener CaO-SiO2-Al2O3-Schlacken

Methode zur Berechnung mittlerer molarer Massen von ringförmigen Anionenkomplexen in CaO-SiO₂-Al₂O₃-Schlacken. Annahme von dreifacher oder vierfacher Koordination für Aluminium. Korrelierung von Schrifttumswerten der Viskosität mit berechneten Anionenmassen.     

碱度对CaO-SiO_2-Al_2O_3-MgO-TiO_2渣系黏度的影响

针对重庆钢铁集团近年来增加澳矿使用量后,炉渣中Al2O3含量的增加对炉渣流动性的不利影响,对重钢高炉的炉渣性能进行了试验研究。以重钢高炉现场渣为基础,利用旋转黏度计测试了Al2O3质量分数为12%、Mg O质量分数为8%、Ti O2质量分数为5%、碱度为1.07~1.50时,Ca O-Si O2-Al2O3-Mg O-Ti O2渣系黏度变化情况;并测量了不同Ti O2含量时炉渣黏度变化情况。研究结果表明:在当前碱度范围内,随着二元碱度增加,炉渣黏度降低,当二元碱度超过1.35时,黏度降低趋势变平缓;炉渣中加入适量Ti O2能降低黏度,改善流动性。     

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.     

Activities of SiO2 and Al2O3 and activity coefficients of FetO and MnO in CaO-SiO2-Al2O3-MgO slags

The activities of SiO₂ and Al₂O₃ in CaO-SiO₂-Al₂O₃-MgO slags were determined at 1873 K along the liquidus lines saturated with 2CaO · SiO₂, 2(Mg,Ca)O · SiO₂, MgO, and MgO · Al₂O₃ phases using a slag-metal equilibration technique. Based on these and previous results obtained in ternary and quaternary slags, the isoactivity lines of SiO₂ and Al₂O₃ over the liquid region on the 0, 10, 20, 30, and 40 mass pct Al₂O₃ planes and those on the 10 and 20 mass pct MgO planes were determined. The activity coefficients of Fe _t O and MnO, the phase boundary, and the solubility of MgO were also determined.     

Phosphorus Capacity of CaO-SiO2-Al2O3-MgO-FexO Slag

The CaO-SiO2-Al2O3-MgO-FexO slag occurs in the production process of Corex ironmaking technology.Most of its metallurgical properties,especially the phosphorus property,are different from the slag produced from blast furnace or converter.In order to explore the dephosphorization ability of CaO-SiO2-Al2O3-MgO-FexO slag,its phosphorus capacity was measured at 1 673 Kby gas-slag-metal equilibrium technique.An iron crucible was used as the reaction vessel,Ag alloy with 0.2% P was used as the metal phase which equilibrated with CaO-SiO2-Al2O3-MgO-FexO slag,and a constant flow of CO-CO2-N2 gas was used to provide oxygen partial pressure in the experiment.The effects of MgO,FexO and basicity on slag phosphorus capacity were investigated by single factor test.The results show that the phosphorus capacity rises firstly and then decreases with increasing MgO content under the condition of basicity 1.3,FexO content of 2% and Al2O3 content of 12%.The phosphorus value reaches maximum as the MgO content is 8%.When the basicity of slag is 1.1,MgO content is 10%,and Al2O3 is 12%,the phosphorus capacity increases with the increase of FexO content.The phosphorus capacity rises linearly when the basicity is increased from 1.1to 1.5.     

Stability of Fluorine-Free CaO-SiO2-Al2O3-B2O3-Na2O Mold Fluxes

Metallurgical and Materials Transactions B - B2O3 and Na2O are key components of fluorine-free mold fluxes for continuous casting, but both are highly volatile, which affects the flux stability....     

Desulfurization Characteristics of CaO-SiO2-BaO-CaF2-Al2O3-MgO Refining Slag

The desulfurizationcapability,as one of the mosti m-portant indexes of refining slag,has great influence onquality of steel.Desulfurization of molten steel with refi-ning slags has become a focal problemconcerned all overthe world[1-4].However,there weref…     

Study on Electronic Conductivity of CaO-SiO2-Al2O3-FeOx Slag System

Inthepast,becauseoflittleknowledgeoftheinfluenceofelectronictransportintheslag,researchworksaboutconductivityoftheslagweremainlyconcentratedonionicconductivity[1—15],so,thedataofelectronicconductivityarefew.Buttheworks[16—19]completedinrecentyearsshowedthatreactionofmetalmeltwithslagiscontrolledbytheconductionofelectronsintheslagundersomeconditions.Theprocessesthatarebeneficialtoelectronimmigratingthroughtheslagbulkandtheslag/metalfilminterfacewilldrasticallyincreasethereactionrateandtheexte…     

CaO-SiO2-Na2O-CaF2-Al2O3-MgO渣系的粘性活化能

采用CaO-Si02-Na20-CaF2-Al2O3-MgO渣系,通过测定粘度和粘性活化能,建立二次回归正交设计模型,借此研究了粘性特征与碱度、Na20含量、CaF2含量、Al2O3含量及MgO含量之间的关系,为设计开发连铸保护渣提供了理论依据。研究结果表明,粘性活化能随着渣中碱度、Na2C03含量和CaF2含量的增加而减小;Al2O3和MgO对粘性活化能的影响与碱度密切相关。连铸保护渣的粘度和粘性活化能具有相似的变化规律。     

Kinetics Analysis of Boron Removal from Silicon through Reactions with CaO-SiO2 and CaO-SiO2-Al2O3 Slags

Metallurgical and Materials Transactions B - Different types of slags have been used to refine silicon, particularly for removing boron impurity from metallurgical grade (MG) silicon. Although a...     

The solution rate of alumina in CaF2-Al2 O3 slags

The rate of solution of A1₂O₃ in CaF₂ + 30 wt pct A1₂O₃ (at 1518° and 1509°C) and CaF₂ + 20 wt pct A1₂O₃ (at 1500°C) liquids has been determined. The operative process is diffusion-controlled, with an interdiffusion coefficient,D for the process varying between 8.5 and 8.1 x 10^-5 sq cms ^- 1 in the CaF₂ + 30 wt pct A1₂O₃ slags, and 4.0 × 10^-5 sq cms ^- 1 in the CaF₂ + 20 wt pct A1₂O₃ slag. Estimations of the rate at which alumina inclusions would react with these slag during the electroslag processing of steels, indicate that electrode inclusions approaching 100 μ in diam will be dissolved.     

帘线钢中CaO-SiO2-Al2O3类夹杂物成分的控制

对帘线钢中CaO-SiO2-Al2O3类夹杂物CaO与SiO2的比值和Al2O3含量进行了研究,并且通过热力学计算对CaO-SiO2-Al2O3系塑性夹杂物的生成条件进行了讨论。结果表明：生产帘线钢时,为了得到塑性良好的夹杂物,钢液的氧活度应控制在0．0056～0．0113,而酸溶铝含量应控制在0．00010％～0．00025％范围内。     

CaO-SiO_2-FeO-P_2O_5-Al_2O_3脱磷渣系中组元活度的计算

2CaO·SiO_2-3CaO·P_2O_5含磷固溶体的生成可提高转炉液相渣的脱磷能力,减少渣量.但目前CaO-SiO_2-FeO-P_2O_5-Al_2O_3渣系中各组元活度的变化规律尚不明确,无法为分析含磷固溶体的形成机理提供理论依据.为此,本文依据分子离子共存理论建立了熔渣组元的活度模型,分析了不同条件下组元活度的变化规律.结果表明:随渣中Al_2O_3含量的增加,2CaO·SiO_2、3CaO·P_2O_5、3FeO·P_2O_5的活度逐渐降低;随着碱度的增大,3CaO·P_2O_5的活度升高,2CaO·SiO_2、3FeO·P_2O_5的活度则呈先升高后降低的趋势;随着渣中FeO含量的增加,2CaO·SiO_2、3FeO·P_2O_5及CaO·Al_2O_3的活度逐渐增大,并在w(FeO)为15%时达到最大值,之后逐渐降低;升高温度会导致CaO、3CaO·SiO_2的活度增大,2CaO·SiO_2的活度降低.     

Viscosity Measurement and Structure Analysis of Cr2O3-Bearing CaO-SiO2-MgO-Al2O3 Slags

Metallurgical and Materials Transactions B - In this study, the effects of different Cr2O3 contents and optical basicity (denoted by Λ) on the viscosity and structure of the Cr2O3-bearing...     

CaO-SiO2-Na2O-CaF2-Al2O3-MgO渣系的结晶温度

通过差热分析仪测定了CaO-SiO2—Na2O-CaF2—Al2O3—MgO系连铸结晶器保护渣的结晶温度。在本实验渣系条件下，连铸保护渣的结晶温度随着渣中CaO／SiO2值、Na2CO3含量、CaF2含量和MgO含量的增加而升高，随着渣中Al2O3含量的增加而降低。化学成分通过改变粘度，来影响晶核形成速度和晶体成长速度，从而决定了连铸保护渣的结晶性能。结晶温度随着保护渣粘度的降低而升高。