Pyrometallurgy Innovation Centre (PYROSEARCH)

  • Influence of MgO on the phase equilibria in the CuxO-FeOy-MgO-SiO2 system in equilibrium with copper alloy-Part II: Results and discussion

    Crivits, Tijl; Hayes, Peter C.; Jak, Evgueni (2018). Phase equilibria in the 'CuO'-'FeO'-MgO-SiO system in equilibrium with copper alloy have been investigated at temperatures between 1 075 and 1 250 °C. A high-temperature equilibration/quenching/electron probe micro-analysis technique has been used to accurately determine the liquid and solid compositions. Results on phase equilibria in the pyroxene and olivine primary phase fields are reported, providing new data on the effect of MgO on the liquidus temperatures in these fields. It was found that increasing MgO concentrations increases the liquidus temperatures in the olivine and pyroxene primary phase fields. The cuprite-delafossite-tridymite-pyroxene eutectic temperature of the quaternary system was determined to be between 1 075 and 1 080 ± 5 °C.

  • Investigation of freeze-linings in a nonferrous industrial slag

    Fallah-Mehrjardi, Ata; Hayes, Peter C.; Vervynckt, Stephanie; Jak, Evgueni (2018). Slag freeze-lining reactor wall protection is a widely used technology in high temperature reaction systems. An air-cooled probe technique was used to investigate the formation of the freeze-linings in an industrial blast furnace slag. The compositions of the phases and the microstructures within the deposits have been characterized. It has been demonstrated that an industrial air-cooled probe can be used to take bath samples from actual smelter operations. In addition, a laboratory-scale experiment was undertaken to investigate the formation, stability, and bath/deposit interface temperature at steady-state conditions. Importantly, the current study has shown that stable steady-state freeze-linings can be obtained in metallurgical reactors operating below the slag liquidus temperature. In spite of the fact that solids are present in the bulk slag, the deposit thickness remains unaltered due to the dynamic conditions present at the deposit/bath interface. The results are consistent with findings obtained on a number of other different slag systems and the proposed dynamic mechanism of deposit stabilization. The findings demonstrate the basis for, and potential benefits that may follow from, operating the high temperature reactors at temperatures below the liquidus temperature, i.e., with solids present, without a catastrophic build-up of solids. This change in design concept could result in significant decreases in operating temperature, energy, and operating cost savings.

  • Investigation of the effect of bath temperature on the bath-freeze lining interface temperature in the CuOx-FeOy-MgO-SiO2 system at copper metal saturation

    Crivits, Tijl; Hayes, Peter; Jak, Evgueni (2018). In pyrometallurgy, freeze lining technology is used to ensure the integrity of the furnace wall. This involves cooling down the wall and solidifying part of the liquid bath material onto the wall, creating a protective layer. In the current study, the cooled probe technique was used to perform a series of laboratory experiments, producing freeze linings under controlled conditions in the CuO-FeO-MgO-SiO system. Earlier research has shown the bath-freeze lining interface temperature at thermal steady state can be at subliquidus temperatures under certain conditions. The current study focuses on the effect of bath temperature on this bath-freeze lining interface temperature and has indicated that increasing the bath temperature increases the interface temperature. Furthermore, the crystals forming the interface did not include the primary phase and formed a non-planar interface at thermal steady state.

  • Phase equilibria and thermodynamics of zinc fuming slags

    Jak, E.; Hayes, P. (2018). A range of materials is treated in zinc fuming processes to recover metal values and produce benign slag waste products. The selection of the optimum process conditions in these various technologies can be greatly assisted by the use of a chemical thermodynamic model of the system. In this paper the effects of slag chemistry on the liquidus temperatures, subliquidus phase equilibria and thermodynamic properties are described by the F*A*C*T computer package with the new thermodynamic database of the ZnO-PbO-FeO-FeO-CaO-SiO system. The implications of these findings for plant practice are discussed.

  • Experimental investigation of gas/matte/spinel equilibria in the Cu-Fe-O-S system at 1473 K (1200 degrees C) and P(SO2)=0.25 atm

    Hidayat, Taufiq; Hayes, Peter C.; Jak, Evgueni (2018). The Cu-Fe-O-S system is the key system for the characterisation of the phase chemistry in high-temperature copper making processes. An experimental study was undertaken to investigate the gas/matte/spinel equilibria in the Cu-Fe-O-S system at 1473 K (1200 A degrees C), P(SO2) = 0.25 atm, and a range of oxygen partial pressures. The experimental methodology involved high temperature equilibration using a primary phase substrate technique in controlled gas atmospheres (CO/CO2/SO2/Ar), rapid quenching of the equilibrated phases, followed by direct measurement of phase compositions using electron probe x-ray microanalysis. Particular attention was given to the analysis of reactions during equilibration and confirmation of the achievement of equilibrium in the present study. The new data provide important information for understanding of the gas/matte/spinel interactions at high temperature and provide an essential foundation for the development of the multicomponent thermodynamic database for copper-containing systems.

  • Experimental Investigation of Gas/Slag/Matte/Tridymite Equilibria in the Cu-Fe-O-S-Si System in Controlled Gas Atmosphere: Experimental Results at 1523 K (1250 °C) and P(SO2) = 0.25 atm

    Fallah-Mehrjardi, Ata; Hidayat, Taufiq; Hayes, Peter C.; Jak, Evgueni (2018). To assist in the optimization of copper smelting and converting processes, accurate new measurements of the phase equilibria of the Cu-Fe-O-S-Si system have been undertaken. The experimental investigation was focused on the characterization of gas/slag/matte/tridymite equilibria in the Cu-Fe-O-S-Si system at 1523 K (1250 °C), P(SO) = 0.25 atm, and a range of P(O)s. The experimental methodology, developed in PYROSEARCH, includes high-temperature equilibration of samples on substrate made from the silica primary phase in controlled gas atmospheres (CO/CO/SO/Ar) followed by rapid quenching of the equilibrium condensed phases and direct measurement of the phase compositions with electron-probe X-ray microanalysis (EPMA). The data provided in the present study at 1523 K (1250 °C) and the previous study by the authors at 1473 K (1200 °C) has enabled the determination of the effects of temperature on the phase equilibria of the multicomponent multiphase system, including such characteristics as the chemically dissolved copper in slag and Fe/SiO ratio at silica saturation as a function of copper concentration in matte. The new data will be used in the optimization of the thermodynamic database for the copper-containing systems.

  • Experimental liquidus studies of the Pb-Cu-Si-O system in equilibrium with metallic Pb-Cu alloys

    Shevchenko, M.; Nicol, S.; Hayes, P. C.; Jak, E. (2018). Phase equilibria of the Pb-Cu-Si-O system have been investigated in the temperature range from 1073 K to 1673 K (800 °C to 1400 °C) for oxide liquid (slag) in equilibrium with solid Cu metal and/or liquid Pb-Cu alloy, and solid oxide phases: (a) quartz or tridymite (SiO) and (b) cuprite (CuO). High-temperature equilibration on silica or copper substrates was performed, followed by quenching, and direct measurement of Pb, Cu, and Si concentrations in the liquid and solid phases using the electron probe X-ray microanalysis has been employed to accurately characterize the system in equilibrium with Cu or Pb-Cu metal. All results are projected onto the PbO-“CuO”-SiO plane for presentation purposes. The present study is the first-ever systematic investigation of this system to describe the slag liquidus temperatures in the silica and cuprite primary phase fields.

  • The Effect of CaO on Gas/Slag/Matte/Tridymite Equilibria in Fayalite-Based Copper Smelting Slags at 1473 K (1200 °C) and P(SO2) = 0.25 Atm

    Fallah-Mehrjardi, Ata; Hayes, Peter C.; Jak, Evgueni (2018). Fundamental experimental studies have been undertaken to determine the effect of CaO on the equilibria between the gas phase (CO/CO/SO/Ar) and slag/matte/tridymite phases in the Cu-Fe-O-S-Si-Ca system at 1473 K (1200 °C) and P(SO) = 0.25 atm. The experimental methodology developed in the Pyrometallurgy Innovation Centre was used. New experimental data have been obtained for the four-phase equilibria system for fixed concentrations of CaO (up to 4 wt pct) in the slag phase as a function of copper concentration in matte, including the concentrations of dissolved sulfur and copper in slag, and Fe/SiO ratios in slag at tridymite saturation. The new data provided in the present study are of direct relevance to the pyrometallurgical processing of copper and will be used as an input to optimize the thermodynamic database for the copper-containing multi-component multi-phase system.

  • Experimental investigation of gas/slag/matte/tridymite equilibria in the Cu-Fe-O-S-Si System in controlled gas atmospheres: Experimental results at 1473 K (1200 A degrees C) and P(SO2)=0.25 atm

    Fallah-Mehrjardi, Ata; Hidayat, Taufiq; Hayes, Peter C.; Jak, Evgueni (2017). Experimental studies were undertaken to determine the gas/slag/matte/tridymite equilibria in the Cu-Fe-O-S-Si system at 1473 K (1200 A degrees C), P(SO2) = 0.25 atm, and a range of P(O-2)'s. The experimental methodology involved high-temperature equilibration using a substrate support technique in controlled gas atmospheres (CO/CO2/SO2/Ar), rapid quenching of equilibrium phases, followed by direct measurement of the chemical compositions of the phases with Electron Probe X-ray Microanalysis (EPMA). The experimental data for slag and matte were presented as a function of copper concentration in matte (matte grade). The data provided are essential for the evaluation of the effect of oxygen potential under controlled atmosphere on the matte grade, liquidus composition of slag and chemically dissolved copper in slag. The new data provide important accurate and reliable quantitative foundation for improvement of the thermodynamic databases for copper-containing systems.

  • Experimental investigation of gas/slag/matte/tridymite equilibria in the Cu-Fe-O-S-Si system in controlled atmospheres: Development of technique

    Fallah-Mehrjardi, Ata; Hidayat, Taufiq; Hayes, Peter C.; Jak, Evgueni (2017). 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/CO/SO/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).

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