Pyrometallurgy Innovation Centre (PYROSEARCH)

  • Selected phase equilibria studies in the Al2O3-CaO-SiO2 system

    Haccuria, Elien; Crivits, Tijl; Hayes, Peter C.; Jak, Evgueni (2016). The AlO-CaO-SiO system provides the basis for describing many important chemical processes. Although the system has previously been extensively studied, recent advances in experimental technique have provided the opportunity to obtain accurate liquidus measurements in the low-silica region at fixed temperatures. The experimental procedures involve equilibration of high-purity oxide powder mixtures at selected temperatures, rapid quenching, and accurate measurement of phase compositions using electron probe X-ray microanalysis. The liquidus isotherms have been determined at selected temperatures between 1503 and 1873 K in the anorthite, gehlenite, pseudowollastonite, corundum, CaAlO, CaAlO, lime, CaSiO, and CaSiO primary phase fields. The results are compared with currently available thermodynamic model predictions of the phase chemistry.

  • Solubility of MgO in high Cu2O slags in equilibrium with Cu metal

    Crivits, T.; Hayes, P. C.; Jak, E. (2016).

  • Integrated experimental and modelling research on copper-making slags

    Hidayat, T.; Shishin, D.; Decterov, S.; Hayes, P. C.; Jak, E. (2016).

  • Fundamental Studies in Ironmaking Slags to Lower Operating Temperatures and to Recover Titania from Slag

    Zhao, Baojun; Jak, Evgueni; Hayes, Peter C. (2016). The eutectic temperature between iron and carbon is 1150 °C. This is the lowest temperature in which Fe-C solution can be tapped from a blast furnace. Current operating temperatures of iron blast furnace are much higher than 1150 ° Cand limited bymelting temperature of the slag. There is room to lower the operating temperature of the iron blast furnace. As a result, coke consumption and CO2 gas emissions can be reduced and campaign length of the furnace can be increased. Akey factor in achieving the low operating temperature of the blast furnace is to use an optimum slag composition that can be tapped at low temperature. Phase equilibria studies have been undertaken in the system "TiO2"-CaO/MgO-Al2O 3SiO2 at carbon saturation. Extensive experimental data are presented in the form of pseudoternary "TiO2"-(CaO+MgO) - (Al2O3+SiO2) at fixedMgO/CaO and Al 2O3/SiO2 ratios.Melting temperatures of complex slag are described as functions of basicity weight ratio (CaO+MgO)/(SiO 2+Al2O3) and TiOx concentration. The phase diagrams determined in this study explain the behaviour of titanium-containing slag such as Panzhihua ironmaking slag. These diagrams will be used for selection of optimum slag composition with low liquidus temperature for both Ti-free and Ticontaining slag. The possibility of lowering ironmaking temperature by adding titania has been discussed based on the experimental data determined in this study. A large amount of iron blast furnace slag containing 20-25 wt% "TiO2" are produced in Panzhihua Iron & Steel. "TiO2" has to be concentrated before it can be efficiently extracted from the slag. It was found in this study that titanium is present in the blast furnace slag mainly in two minerals, perovskite CaTiO 3 and pseudobrookite (Mg2+,Al3+,Ti 3+,Ti4+)3O5. Electron probe X-ray microanalysis (EPMA) has been used to determine phase assemblage of the slag quenched from high temperature and the compositions of the phases. It was found that "TiO2" is 58 wt% in perovskite and 80-90 wt% in pseudobrookite. The particle size of the pseudobrookite is much larger than that of the perovskite. It was found that the composition of the current Panzhihua ironmaking slag is located in the perovskite primary phase field. The maximum "TiO2" concentration in the recovered materials is only 58 wt% if the crystal phase is perovskite. With the information provided in this study it may be possible to recover "TiO2" from the Panzhihua slag in the form of pseudobrookite so that recovered materials contains 80-90 wt% "TiO2" and can be used directly for production of pure TiO2.

  • Coupled experimental and thermodynamic modelling studies of slags for metallurgical smelting and coal combustion systems

    Jak, E.; Degterov, S.; Zhao, B.; Pelton, A. D.; Hayes, P. C. (2016). An extensive research program focused on the characterization of various metallurgical complex smelting and coal combustion slags is being undertaken. The research combines both experimental and thermodynamic modeling studies. The approach is illustrated by work on the PbO-ZnO-AlO-FeO-FeO-CaO-SiO system. Experimental measurements of the liquidus and solidus have been undertaken under oxidizing and reducing conditions using equilibration, quenching, and electron probe X-ray microanalysis. The experimental program has been planned so as to obtain data for thermodynamic model development as well as for pseudo-ternary liquidus diagrams that can be used directly by process operators. Thermodynamic modeling has been carried out using the computer system FACT, which contains thermodynamic databases with over 5000 compounds and evaluated solution models. The FACT package is used for the calculation of multiphase equilibria in multicomponent systems of industrial interest. A modified quasi-chemical solution model is used for the liquid slag phase. New optimizations have been carried out, which significantly improve the accuracy of the thermodynamic models for lead/zinc smelting and coal combustion processes. Examples of experimentally determined and calculated liquidus diagrams are presented. These examples provide information of direct relevance to various metallurgical smelting and coal combustion processes.

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