The amount of waste electrical and electronic equipment (WEEE) in the world has grown rapidly during recent decades, and with the depletion of primary ores, there is urgent need for industries to study new sources for metals. Waste printed circuit boards (WPCB) are a part of WEEE, which have a higher concentration of copper and precious metals when compared to primary ore sources. PCB materials can be processed using pyrometallurgical routes, and some industrial processes, such as copper flash smelting, have utilized this type of waste in limited amounts for years. For the purpose of recycling these materials through smelting processes, this work studied the behavior of WPCB scrap when dropped on top of molten slag. A series of experiments was carried out during this research at a temperature of 1350 °C, in an inert atmosphere with different melting times. The time required for complete melting of the PCB pieces was 2–5 min, after which molten alloy droplets containing Cu, Pb, Sn, Ni, Au, and Ag formed and started descending toward the bottom of the crucible. The ceramic fraction of the PCB material mixed with slag and the polymer fraction was pyrolyzed during the high-temperature experiments. The results give an understanding of PCB melting behavior and their use as a part of the smelting furnace feed mixture. However, more research is needed to fully understand how the different elements affect the process as the amount of PCB in the feed increases. The physical behavior and distribution of PCB materials in fayalite slag during the smelting process are outlined, and the results of this work form a basis for future studies about the chemical reaction behavior and kinetics when PCB materials are introduced into the copper smelting process.

Due to the importance of the physicochemical properties of slag in the recovery of low-titanium ores and by-products, the equilibrium phase relationships of the CaO-MgO-Al 2 O 3-SiO 2-TiO 2 system were experimentally determined using a high-temperature equilibration and quenching method at 1300°C and 1400°C. The equilibrium information was obtained by scanning electron microscope-energy dispersive x-ray spectrometer. Perovskite, spinel and pseudobrookite solid solution phases with MgOAE2TiO 2 and Al 2 O 3 AETiO 2 end members were found to be coexisting with the liquid phase. The 1300°C and 1400°C isotherms were then constructed on a CaO-SiO 2-TiO 2-8 wt.% MgO-14 wt.% Al 2 O 3 quasi-ternary section. Comparisons with predictions by Factsage and MTDATA indicated that the computational results agreed well only in the primary phase field of perovskite, while clear deviations existed within other primary phase fields. Therefore, the present results improve our knowledge about the utilization of titanium resources, and are also significant in providing novel equilibrium data for updating the related thermodynamic databases.

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Improving metal-slag separation in pyrometallurgical processes is increasingly important. Due to the harsh conditions, direct observations of the molten phases behavior in the settler of the Outotec Flash Smelting Furnace (FSF) are not possible and the ways to improve metal settling can only be studied by simulation and modelling. This study focuses on kinetics and mechanisms of the chemical reactions between matte droplets and slag, which were investigated in laboratory scale heat-quench equipment at typical smelting temperature of 1300 °C as a function of time in both air and argon atmosphere. The reaction mechanism in the FSF settler was formulated and results in argon atmosphere also indicate that the oxidation of cuprous sulfide by ferric ions in the slag contribute strongly to the copper losses in the slag.

We investigated the phase relations of the SiO2-MgO-TiO2 system in air at 1500°C using the high-temperature isothermal equilibration/quenching technique, followed by x-ray diffraction measurements and direct phase analysis using scanning electron microscopy coupled with x-ray energy dispersive spectrometry. One single liquid phase domain, five two-phase domains (liquid-TiO2, liquid-cristobalite, liquid-MgO·SiO2, liquid-2MgO·SiO2, and liquid-MgO·2TiO2), and five three-phase regions (liquid-TiO2-MgO·2TiO2, liquid-MgO·SiO2-cristobalite, liquid-TiO2-cristobalite, liquid-MgO·SiO2-2MgO·SiO2 and liquid-2MgO·SiO2-MgO·2TiO2) were observed. We constructed a 1500°C isothermal phase diagram based on the experimentally measured liquid compositions. We compared simulations using MTDATA and FactSage thermodynamic software and their databases with the experimental results obtained in this study. These results can be used to provide guidelines for updating the MTDATA and FactSage titania-bearing thermodynamic databases by reassessing the thermodynamic properties of the phase with new experimental data.