Thermodynamics of surfaces and adsorption in the Fe-S, Fe-N, and Fe-S-N systems at 1823 K

The present investigation calculates the surface tension and adsorption functions of the Fe-S, Fe-N, and Fe-S-N melts at 1823 K using the modified form of Butler’s equations and the derived values of the surface interaction parameters of the systems. The calculated values are found to be in good agreement with those of the experimental data of the systems. The present analysis indicates similar adsorption behavior of sulfur for the Fe-S and Fe-S-N systems at 1823 K. Although a linear adsorption behavior is observed in the Fe-N system, an inverse relationship in the adsorption behavior exists between sulfur and nitrogen in the Fe-S-N system.     

Thermodynamics and phase relationships of transition metal-sulfur systems: Part III. Thermodynamic properties of the Fe-S liquid phase and the calculation of the Fe-S phase diagram

An associated solution model is applied to describe the thermodynamic behavior of Fe-S liquid. This model assumes the existence of ‘FeS’ species in addition to Fe and S in the liquid. With two solution parameters for each of the binaries Fe-‘FeS’ and ‘FeS’-S, this model accounts for the compositional dependence of the thermodynamic properties of Fe-S liquid from pure Fe to pure S over a wide range of temperature. The binary Fe-S does not contribute significantly to the excess Gibbs energy of the liquid due to the rather small dissociation constant of ‘FeS’ to Fe and S. Using this model for the liquid phase and a defect thermodynamic model for the pyrrhotite phase, the Fe-S phase diagram is calculated. The calculated diagram is in excellent agreement with the experimental data, accounting for the range of homogeneity of pyrrhotite at all temperatures. Both the thermodynamic and phase diagram data are obtained from the literature. Formerly Post-Doctoral Research Associate, Materials Department, College of Engineering and Applied Science, University of Wisconsin-Milwaukee.     

Thermodynamics and phase relationships of transition metal-sulfur systems: Part V. A reevaluation of the Fe-S system using an associated solution model for the liquid phase

The relevant thermodynamic and phase equilibrium data for the Fe-S binary system have been reevaluated in light of more recent data. An associated solution model is used to describe the thermodynamic properties of the liquid phase as a function of composition and temperature. For the pyrrhotite phase, a statistical thermodynamic model based on the formation of Frenkel defects in the lattice is used. For the austenite and ferrite phases, the solute is assumed to follow Henry’s law, and pyrite is taken to be a stoichiometric compound. The model parameters for the various phases are obtained by evaluating all relevant experimental data reported in the literature. The calculated phase diagram is in good agreement with the experimental data. The calculated sulfur activity values for the liquid phase agree well with experimental values including those at higher sulfur concentrations. This is an improvement of an earlier evaluation by Sharma and Chang using the same model with the same number of parameters.     

Thermodynamics of the Ca-S-O,Mg-S-O,and La-S-O systems at high temperatures

High temperature thermodynamic data for equilibria in the Ca-S-O, Mg-S-O, and La-S-0 systems were determined by a galvanic cell technique using calcia stabilized zirconia (CSZ) solid electrolytes. The measured emf data were used to calculate the standard free energy changes of the following reactions: [1] CaO(s) + 1/2S₂(g) → CaS(s) + 1/2O₂(g) 1000 to 1350 K ΔG° = 21906.9 − 0.8T(K)(±400 cal) = 91658 − 3.37 (±1700 J) [2] CaS(s) + 2O₂(g) → CaSO₄(s) 1050 to 1450 K ΔG° = -227530.7 + 80.632T(K) (±400 cal) = -951988.5 + 337.4T (±1700 J) [3] CaO(s) + 3/2O₂(g) + 1/2S₂(g) → CaSO₄(s) 1050 to 1340 K ΔG° = -204892.7 + 79.83T(K)(±400 cal) = -857271.1 + 334.0T (±1700 J) [4] MgO(s) + 1/2S₂(g) → MgS(s) + 5O₂(g) 1000 to 1150 K ΔG° = 45708.6 − 2.897(K)(±500 cal) = 191244.8 − 12.1T (±2100 J) [5] La₂O₃(s) + 1/2S₂(g) → La₂O₂S(s) + 1/2O₂(g) 1080 to 1350 K ΔG° = 17507 − 2.32T(K)(±380 cal) = 73249.3 − 9.7T (±1600 J) [6] La₂O₃S(s) + S₂(g) → La₂S₃(s) + O₂(g) 950 to 1120 K ΔG° = 70940 + 2.25T(K)(±500 cal) = 296812.9 + 9.47 (±2100 J) The ΔG° values of reaction [5] were combined with the literature data for ΔG°_f(La₂O₃) to obtain the standard free energy of formation of La₂O₂S at high temperatures. The values of ΔG°_f thus calculated for La₂O₂S were combined with the ΔG° data for reaction [6] to obtain the standard free energy of formation of La₂S₃ at high temperatures.     

Gibbs Energy Modeling of the Cu-S Liquid Phase: Completion of the Thermodynamic Calculation of the Cu-S System

Metallurgical and Materials Transactions B - A thorough review and critical evaluation of all experimental sulfur potential and phase diagram data available from the literature has been made for...     

Thermodynamics of binary systems using interaction parameters

A four-parameter equation for determining the excess integral property of a binary system is deduced based on the Maclaurin infinite series. The series is expressed separately in the neighborhood of each of the pure components of the system. The components are subjected to appropriate boundary conditions at the various stages of the treatment. The present form of the function is found to be capable of interpreting thermodynamic properties of several relatively weakly interacting binary systems based on the present equation. The infinite dilution parameters compare favorably with the values reported in the literature.     

低碱度铜硫分离新工艺工业应用

介绍了低碱度铜硫分离新工艺在大山选矿厂的生产应用情况,说明了低碱度工艺比石灰高碱度工艺实现铜硫分离的技术特点;对生产应用中存在的问题和解决方法进行了分析讨论,取得了显著的经济效益和社会效益。     

Thermodynamics of Ca-CaF2 and Ca-CaCI2 systems for the dephosphorization of steel

Calcium is soluble in halide salts which can be used to remove phosphorus from steel as a phosphide ion. The activity and activity coefficient of calcium phosphide, and the equilibrium phosphorus distribution ratio between Ca-CaF₂ and Ca-CaCl₂ fluxes and pure solid iron were measured as a function of the Ca composition in the flux at 1350 °, 1400 °, and 1450 °. The Ca-Ca halide fluxes were equilibrated with pure solid iron and a Ag-Ca alloy in an iron crucible under an Ar atmosphere. The Ag-Ca alloy was used to maintain a constant chemical potential of calcium. Phosphorus distribution between between these fluxes and solid pure iron increased with increasing calcium activity and decreasing temperature. The activity coefficient of γ_{Ca 1.5 P} was calculated to be 36.6 at 1350 ° and 11.0 at 1450 ° for a calcium activity of 0.2 (wt pct Ca = 2.5) in the Ca-CaF₂; the activity coefficient increases with increasing Ca in the flux. In addition, the activity of Ca in the Ca-Ca halide fluxes was determined. The equilibrium phosphorus distribution ratio between Ca-Ca halide systems and molten chromium steel was calculated as functions of Cr and C contents of the metal and calcium activity in the flux at 1600 °C by using γ_{Ca 1.5 P} obtained in the present work. This ratio was found to be about 20 for 18 pct Cr stainless steel at 1600 °. Formerly a Graduate Student at Carnegie Mellon University     

Thermodynamics of the Fe-Ni-O and Fe-Ni systems at 1065 K to 1380 K

Abstract

Equilibrium oxygen potentials and compositions were measured in the temperature range of 1065 to 1380 K by equilibrating the Fe-Ni-O mixtures in flowing CO/CO₂ gas atmospheres, identifying the phases by X-ray diffraction and metallography, and analyzing the phases by electron microprobe analysis. The data at 1280 K agree with well-estabished data for the Fe-O and Ni-O binaries and with previous published measurements in the wustite-alloy region of the Fe-Ni-O ternary. The data for the spinel-alloy region at 1280 K are in excellent agreement with recent measurements by a similar technique, but disagree with previous data. This is attributed to deficiencies in the experimental techniques used in previous measurements. New data are presented at 1065 K, 1180 K and 1380 K.

The derived activities of iron and nickel in iron-nickel alloys agree with recent mass spectrometric data.

Résumé

Les potentiels d'oxygime des melanges Fe-Ni-O, en équilibre avec des atmosphères de CO-CO₂, ont été mesurés entre 1065 °K et 1380°K. Les phases solides ont été identifiées par diffraction rayons-X, et par étude métallographique: leur composition a été determinée ,à l'aide d'une microsonde électronique. Les valeurs calculées à 1280°K sont en accord avec celles normalement acceptées sur les systèmes binaires FeO et NiO aussi bien qu'avec les résultats préalablement publies dans la region “wustite-alliage” du système ternaire Fe-Ni-O. Les résultats pour les compositions spinel-alli age à 1280°K sont en bon accord avec des mesures récentes, obtenues en utilisant une technique éxperimentale sembl able, mais ils sont en désaccord avec des résultats antérieurs que nous jugeons moins précis à cause de la technique éxperimentale utilisée. De plus, de nouvelles valeurs à 1065 °K, 1180 °K et à1380 °K sont présentées.

Les activités deduites pour Ie Fe et le Ni, dans les alliages Fe-Ni, correspondent bien avec les valeurs récentes obtenues, par spectrométrie de masse.     

Thermodynamics of surfaces and adsorption in the Fe-O and Fe-O-N systems at 1823 K

The present investigation calculates the surface tension and adsorption functions of the Fe-O and Fe-O-N melts at 1823 K using the modified form of Butler’s equations and the derived values of the surface interaction parameters of the systems. The calculated values are found to be in good agreement with those of the experimental data of the systems. The present analysis indicates a characteristic saturation behavior of oxygen in the Fe-O system at 1823 K, whereas a linear adsorption behavior is observed in the Fe-N system. An inverse relationship in the adsorption behavior, which exists between oxygen and nitrogen in the Fe-O-N system, is similar to that observed in our earlier study of the Fe-S-N system.     

铜硫混合矿的分选试验

本文介绍在银山矿铜硫选矿指标不稳定、铜在硫精矿中损失严重的情况下．作者用6种不同矿区、不同比例的矿样做了两种流程、10组闭路选矿试验，其中以低品位综合矿试验为代表，与现场铜硫系统的生产进行了对比分析，为选矿工艺的改进和提高技术指标提供依据。     

重-浮联合流程综合回收某铜硫尾矿中白钨矿的试验研究

针对广东省某铜硫尾矿中钨资源长期未被利用的问题,研究采用重-浮联合流程综合回收尾矿中的钨。根据该尾矿中钨含量低,钨和其他矿物之间赋存状态复杂等矿石性质,对WO_3含量0.11%的铜硫尾矿,采用LP900螺旋溜槽重选设备对钨进行粗选,钨粗精矿浮选脱硫后再采用摇床进一步富集钨。试验获得了WO_3品位32.16%、回收率30.29%的钨精矿,同时综合回收了S含量45.89%、回收率57.28%的硫精矿,使得丢弃在铜硫尾矿中的钨、硫资源得到较好利用。     

Vapor pressure determination of arsenic activity in a molten Cu-Fe-S matte

The activity of As in a molten copper smelting matte of composition 35.0 mass pct Cu, 35.8 mass pct Fe, and 29.9 mass pct S has been derived from vapor pressure measurements at 1336 K. The initial As doping level was 1.6 mass pct. Mass spectrometry showed the principal vapor phase species to be As₂; smaller amounts of AsS and S₂ were also present. The activity coefficient of As in the matte, γ (As), was found to have the value 0.7 ±0.2 (mole fraction)^-1 in the composition range studied. Activity values found in the present study were an order of magnitude smaller than those determined by an isopiestic method, and were about two orders of magnitude greater than those derived from measurements of As distribution between copper and white metal. The vapor pressure method is believed to be more direct and reliable; sources of error in the various methods are discussed.     

Thermodynamics and phase relationships of transition metal-sulfur systems: I. The cobalt-sulfur system

Thermodynamic activity of sulfur in the Co₄S₃±y, Co₉S₈ and C0₁-y, phases was determined as a function of composition over the temperature interval, 875 to 1168 K, using a gas equilibration technique. The data obtained in the present study as well as those reported in the literature are evaluated to yield thermodynamic equations of state for all the intermediate phases. Several forms of the Co-S phase diagram are presented. Formerly Research Assistant, Materials Department, College of Engineering and Applied Science, University of WisconsinMilwaukee     

Thermodynamics of formation of compounds in the Ce-Mg,Nd-Mg,Gd-Mg,Dy-Mg,Er-Mg,and Lu-Mg binary systems in the temperature range 650°to 930°K

The vapor pressures of magnesium over a series of two-phase alloys of Mg with Ce, Nd, Gd, Dy, Er, and Lu have been measured by the Knudsen effusion technique in the temperature range 650 to 930 K. These vapor pressure measurements were combined with data concerning the terminal solubility of magnesium in the rare earths and the vapor pressure of pure magnesium to evaluate the standard free energies of formation of the twenty-four intermediate phases in these six binary systems. Trends in the data correlate with the number of unpaired 4f electrons of the lanthanon component, and the inference is that the 4f electrons make a contribution to the bonding interactions. There is also evident a shift in the pattern of the free energies of formation of the phases with the shift occurring as the atomic number of the lanthanon component is increased. This implies modification of the bonding interactions by some additional factor which might be either a size factor or a crystal-environmental dependence of the strength of the 4f bonding contributions. Experiments are proposed to distinguish between the possibilities. J.E. PAHLMAN, Formerly Graduate Student, Department of Metallurgy, Iowa State University, Ames, Iowa