Taufiq Hidayat

Thermodynamic Optimization of the Ca-Fe-O System

The present study deals with the thermodynamic optimization of the Ca-Fe-O system. All available phase equilibrium and thermodynamic experimental data are critically assessed to obtain a self-consistent set of model parameters for the Gibbs energies of all stoichiometric and solution phases. Model predictions of the present study are compared with previous assessments. Wüstite and lime are described as one monoxide solution with a miscibility gap, using the random mixing Bragg-Williams model. The solubility of CaO in the “Fe3O4” magnetite (spinel) phase is described using the sublattice model based on the Compound Energy Formalism. The effect of CaO on the stability of the spinel phase is evaluated. The liquid CaO-FeO-Fe2O3 slag is modeled using the Modified Quasichemical Formalism. Liquid metal phase is described as a separate solution by an associate model.

Experimental Investigation of Gas/Slag/Matte/Tridymite Equilibria in the Cu-Fe-O-S-Si System in Controlled Atmospheres: Development of Technique

The majority of primary pyrometallurgical copper making processes involve the formation of two immiscible liquid phases, i.e., matte product and the slag phase. There are significant gaps and discrepancies in the phase equilibria data of the slag and the matte systems due to issues and difficulties in performing the experiments and phase analysis. The present study aims to develop an improved experimental methodology for accurate characterisation of gas/slag/matte/tridymite equilibria in the Cu-Fe-O-S-Si system under controlled atmospheres. The experiments involve high-temperature equilibration of synthetic mixtures on silica substrates in CO/CO2/SO2/Ar atmospheres, rapid quenching of samples into water, and direct composition measurement of the equilibrium phases using Electron Probe X-ray Microanalysis (EPMA). A four-point-test procedure was applied to ensure the achievement of equilibrium, which included the following: (i) investigation of equilibration as a function of time, (ii) assessment of phase homogeneity, (iii) confirmation of equilibrium by approaching from different starting conditions, and (iv) systematic analysis of the reactions specific to the system. An iterative improved experimental methodology was developed using this four-point-test approach to characterize the complex multi-component, multi-phase equilibria with high accuracy and precision. The present study is a part of a broader overall research program on the characterisation of the multi-component (Cu-Fe-O-S-Si-Al-Ca-Mg), multi-phase (gas/slag/matte/metal/solids) systems with minor elements (Pb, Zn, As, Bi, Sn, Sb, Ag, and Au).

Thermodynamic modelling of the "cu2O"-SiO2, "cu2O"-CaO, and "cu2O"-CaO-SiO 2 systems in equilibrium with metallic copper

Abstract Phase equilibrium and thermodynamic experimental data in the Cu2O – SiO2, Cu2O – CaO, and Cu2O – CaO – SiO2 systems in equilibrium with metallic copper have been critically reviewed. The Modified Quasichemical and Bragg–Williams models in the FactSage computer package were used to describe the Gibbs energy of the molten slag phase as a function of composition and temperature. The available data have been used to optimize simultaneously a set of parameters in thermodynamic model equations for the Gibbs energy of liquid slag. The present thermodynamic optimization was carried out as part of the development of a thermodynamic database of copper-containing slag systems.

Integrated Experimental and Modelling Research for Non-Ferrous Smelting and Recycling Systems

The chemistries of industrial pyrometallurgical non-ferrous smelting and recycling processes are becoming increasingly complex. Optimisation of process conditions, charge composition, temperature, oxygen partial pressure, and partitioning of minor elements between phases and different process streams require accurate description of phase equilibria and thermodynamics which are the focus of the present research. The experiments involve high temperature equilibration in controlled gas atmospheres, rapid quenching and direct measurement of equilibrium phase compositions with quantitative microanalytical techniques including electron probe X-ray microanalysis and Laser Ablation ICP-MS. The thermodynamic modelling is undertaken using computer package FactSage with the quasi-chemical model for the liquid slag phase and other advanced models. Experimental and modelling studies are combined into an integrated research program focused on the major elements Cu-Pb-Fe-O-Si-S system, slagging Al, Ca, Mg and other minor elements. The ongoing development of the research methodologies has resulted in significant advances in research capabilities. Examples of applications are given.

Advanced Thermochemical Fundamental and Applied Research to Improve the Integrity of the Steel Water Jacketed Furnace at Port Pirie

Lead blast furnace water-jacket stability was investigated by examining samples from the Port Pirie Lead Smelter. The compositions of the phases formed in the samples were analysed using Scanning Electron Microscopy (SEM) and Electron Probe X-ray Microanalyser (EPMA). Phase equilibria analysis and thermodynamic modelling was undertaken using FactSage with latest thermodynamic database for the slag/matte/metal/speiss/solids multi-component Cu2O–PbO–ZnO–Al2O3–CaO–MgO–FeO–Fe2O3–SiO2–S major and As–Bi–Sb–Sn–Ag–Au minor elements system. Results indicated that the stability of the water-jacket steel wall without freeze-lining is influenced by formation of the complex Fe-rich speiss phase at critical As concentrations. The integrity of the furnace walls with freeze-lining is critically dependent of the stability of the oxide-based freeze-lining which is dependent on various factors including most critical one—the proportion of solids determined by the slag chemistry and fluxing. Thermodynamic modelling of the lead blast furnace operation indicated limiting thermochemical conditions for the water-jacket stability. Factors and controls critical to the water-jackets integrity are discussed.

Microanalysis and Experimental Techniques for the Determination of Multicomponent Phase Equilibria for Non-ferrous Smelting and Recycling Systems

Accurate description of complex phase equilibria provide the foundations for the improvement of non-ferrous pyrometallurgical smelting and recycling processes. Recent advances in microanalysis and experimental techniques enable accurate phase equilibria characterisation. Quantitative microanalytical techniques including Electron Probe X-ray Microanalysis and Laser Ablation ICP-MS enable the concentrations of major and minor elements present in different phases in samples to be accurately measured providing data that cannot be obtained using bulk chemical analysis techniques. High-temperature equilibration experiments coupled with the subsequent analysis of elementary reactions at micro- and macro-scales ensure the attainment of equilibrium conditions, and therefore, ensure true phase equilibria information is obtained. Examples of the application of the improved methodology on the investigation of phase equilibria of low-order and complex, multi-component gas/slag/matte/metal/solids Cu2O–PbO–ZnO–Al2O3–CaO–MgO–FeO–Fe2O3–SiO2–S systems and the distribution of minor element are provided. The experimental study is closely integrated with thermodynamic database development for the above system. Example of implementation of the research outcomes into industrial operations is demonstrated.

Modelling of liquid phases and metal distributions in copper converters: transferring process fundamentals to plant practice

ABSTRACT The quantity and accuracy of fundamental data available on copper smelting and converting systems has greatly increased over the past several decades. Engineers need no longer rely on approximations and interpolation of chemical behaviour from idealised or simplified low-order systems. Sophisticated thermodynamic databases and dedicated thermodynamic computer platforms make it possible to predict the outcomes of complex multicomponent, multiphase reactions, and to present this information in forms that are useful for industrial practice. In the present paper a summary and review of phase equilibria data on key Cu-Fe-O-S sub-systems including Ca, Si and minor elements, is provided, as are examples of the application of thermodynamic and thermochemical calculations to the modelling of copper converting. As further information on chemical behaviour and integration with process models become available these sophisticated predictive tools and approaches will become increasingly used to improve metallurgical process design and efficiency, and to optimise the productivity of integrated copper production operations.

High-temperature experimental and thermodynamic modelling research on the pyrometallurgical processing of copper

Uncertainty in the metal price and competition between producers mean that the daily operation of a smelter needs to target high recovery of valuable elements at low operating cost. Options for the improvement of the plant operation can be examined and decision making can be informed based on accurate information from laboratory experimentation coupled with predictions using advanced thermodynamic models. Integrated high-temperature experimental and thermodynamic modelling research on phase equilibria and thermodynamics of copper-containing systems have been undertaken at the Pyrometallurgy Innovation Centre (PYROSEARCH). The experimental phase equilibria studies involve high-temperature equilibration, rapid quenching and direct measurement of phase compositions using electron probe X-ray microanalysis (EPMA). The thermodynamic modelling deals with the development of accurate thermodynamic database built through critical evaluation of experimental data, selection of solution models, and optimization of models parameters. The database covers the Al-Ca-Cu-Fe-Mg-O-S-Si chemical system. The gas, slag, matte, liquid and solid metal phases, spinel solid solution as well as numerous solid oxide and sulphide phases are included. The database works within the FactSage software environment. Examples of phase equilibria data and thermodynamic models of selected systems, as well as possible implementation of the research outcomes to selected copper making processes are presented.

Thermodynamic modelling of liquid slag-matte-metal equilibria applied to the simulation of the Peirce-Smith converter

Computer simulation plays an increasingly important role in improving the environmental and economic performance of pyrometallurgical extraction processes. The thermodynamic description of the chemical systems involved is at the core of such advanced simulation software. A thermodynamic database has been developed to describe the phase relations and chemical reactions in the Al—Ca—Cu—Fe—Mg—O—S—Si chemical system with support from the leading copper producers. The database contains model parameters for gas, liquid slag, liquid matte and metal, spinel and numerous solid phases. Models based on the Modified Quasichemical Formalism were used for the slag, matte and liquid metal. The internal consistency of the database provides accurate and reliable predictions outside of the usual operating conditions. The development of the database was closely integrated with the experimental studies of this chemical system. The database works in the environment of FactSage software. The application of thermodynamic modelling is illustrated by the example of the Peirce-Smith converter.