Search Results (8)

This paper presents the results of a study on the development of a processing technology for pyrite–cobalt concentrates to obtain iron oxide pigments (Fe₂O₃ and Fe₃O₄) via high-temperature hydrolysis. It was found that, in a single operation, the concentrate can be effectively purified from lead, zinc, and copper, yielding an iron–nickel–cobalt product suitable for further processing by standard technologies, such as smelting into ferronickel. The scientific originality of research concludes in a mechanism of stepwise selective chloride volatilization, which was established as follows: stage I (500–650 °C)—removal of lead; stage II (700–750 °C)—chlorination of copper and iron; stage III (850–900 °C)—volatilization of nickel and cobalt. Microprobe analysis of the powders obtained from high-temperature hydrolysis of FeCl₂·4H₂O and FeCl₃·6H₂O revealed the resulting Fe₃O₄ and Fe₂O₃ powders with particle sizes 50 μm and 100 μm. A visual color palette was created, corresponding to different Fe₃O₄/Fe₂O₃ ratios in the pigment composition—ranging from black (magnetite) to red (hematite)—and potential application areas. For the first time, the new technological scheme was proposed of pigments Fe₂O₃ and Fe₃O₄ production from pyrite–cobalt concentrates via combination of oxidized roasting with subsequent chlorination and high-temperature hydrolysis of the products. Full article

Due to growing concern over environmental impacts and the pressure to lower carbon footprints in the metals industry, hydrogen (H₂) has gained attention as a promising alternative for the replacement of carbon as a reductant and fuel. This paper evaluates the potential use of hydrogen as an energy source and reducing agent during the processing of waste printed circuit boards (waste PCBs) from e-waste through black copper smelting. The effect of the use of carbon and hydrogen during the reduction–oxidation process was analysed and compared from the perspective of thermodynamics and heat balance. The thermodynamic analyses of waste-PCB processing were carried out using the FactSage thermochemical package for the smelting process at temperatures from 1473 K to 1673 K (1200–1400 °C). The results show that the CO₂ emissions can be reduced by 73% when hydrogen is used as the reducing agent. A minimum of 10 wt% of waste PCBs in the feed material can be used to replace the necessary carbon to supply heat for the reduction process. The addition of waste PCBs can increase the volume of slag and affect the composition of the off gas. Full article

Electronic goods are a major consumer of many critical metals, including copper, nickel, tin, zinc, lead, and precious metals. The processing of end-of-life electronic equipment (E-Scrap) is becoming increasingly important to maintain the supply of the critical metals required globally, and to reduce environmental pollution. Currently, the dominant route for E-Scrap processing is pyrometallurgical processing, with the first stage of processing being reductive smelting to produce a black copper and a ‘clean’ discard slag. The management of the slag in this first step is central to the success of the E-Scrap recycling process. The E-Scrap ISASMELT™ furnace has a highly turbulent bath, providing conditions that generate high rates of zinc fuming and allow a wide range of operable slag conditions. This enables efficient E-Scrap smelting to occur, whilst overcoming the challenges associated with alternative technologies. Operable slag compositions and high zinc fuming are heavily influenced by kinetic processes, with piloting critical to understanding the performance of this process. ISASMELT™ pilot tests were performed, with a wide range of fluxing targets tested to confirm these benefits. The testing demonstrated that high levels of zinc fuming (>80%) are obtained in the E-Scrap ISASMELT™ furnace, decreasing the iron and silica flux additions required to manage the detrimental viscosity effects of zinc in the slag. In addition, it was demonstrated that slags containing high concentrations of alumina (>10 wt%) are operable in an ISASMELT™ furnace. The ISASMELT™ technology was demonstrated to be the only E-Scrap furnace technology able to produce a ‘clean’ discard slag with low concentrations of zinc and minimal fluxing requirements. Full article

Chromium slag and copper smelting waste slag are solid wastes generated in the process of industrial production of chromium salt and copper metal, respectively. In this study, chromium slag and copper smelting waste slag were used as raw materials to produce black ceramic tiles. It can not only reduce environmental pollution but also increase their utilization value. The chromaticity values of ceramic tiles (L*, a*, and b*), which are color models developed by the International Commission on Illumination, were measured using a colorimeter. The phases and microstructure of the ceramic tile were analyzed by X-ray diffractometer (XRD), scanning electron microscope and energy-dispersive X-ray spectrometry (SEM-EDS), respectively. The effects of different process parameters on the coloring performance of ceramic tiles were also investigated. The results show that the color of ceramic tile is the best when the Fe/Cr ratio is 1.5, the sintering temperature is 1200 °C, the holding time is 30 min and the ceramic tile is cooled in the furnace. The values of L*, a*, and b* are, respectively, 22.5, 0, and −1.6. The compressive strength of ceramic tile and the leaching concentration of Cr(VI) are 127.2 MPa and 3.31 mg/L, respectively, which can meet the relevant national standards. Full article

Due to the increasing demand for battery raw materials such as cobalt, nickel, manganese, and lithium, the extraction of these metals not only from primary, but also from secondary sources like spent lithium-ion batteries (LIBs) is becoming increasingly important. One possible approach for an optimized recovery of valuable metals from spent LIBs is a combined pyro- and hydrometallurgical process. According to the pyrometallurgical process route, in this paper, a suitable slag design for the generation of slag enriched by lithium and mixed cobalt, nickel, and copper alloy as intermediate products in a laboratory electric arc furnace was investigated. Smelting experiments were carried out using pyrolyzed pelletized black mass, copper(II) oxide, and different quartz additions as a flux to investigate the influence on lithium-slagging. With the proposed smelting operation, lithium could be enriched with a maximum yield of 82.4% in the slag, whereas the yield for cobalt, nickel, and copper in the metal alloy was 81.6%, 93.3%, and 90.7% respectively. The slag obtained from the melting process is investigated by chemical and mineralogical characterization techniques. Hydrometallurgical treatment to recover lithium is carried out with the slag and presented in part 2. Full article

Recycling of metals from different waste streams must be increased in the near future for securing the availability of metals that are critical for high-tech applications, such as batteries for e-mobility. Black copper smelting is a flexible recycling route for many different types of scrap, including Waste Electrical and Electronic Equipment (WEEE) and some end-of-life energy storage materials. Fundamental thermodynamic data about the behavior of battery metals and the effect of slag additives is required for providing data necessary for process development, control, and optimization. The goal of our study is to investigate the suitability of black copper smelting process for recycling of battery metals lithium, cobalt, manganese, and lanthanum. The experiments were performed alumina crucibles at 1300 °C, in oxygen partial pressure range of 10⁻¹¹–10⁻⁸ atm. The slags studied contained 0 to 6 wt% of MgO. Electron probe microanalysis (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) techniques were utilized for phase composition quantifications. The results reveal that most cobalt can be recovered into the copper alloy in extremely reducing process conditions, whereas lithium, manganese, and lanthanum deport predominantly in the slag at all investigated oxygen partial pressures. Full article

Ferrous-calcium-silicate (commonly known as FCS) slags are used in the valuable metal recycling from urban ores through both primary and secondary copper smelting processes. In the present study, the structure of selected FCS-MgO (FCSM) and FCS-MgO-Cu₂O-PdO (FCSM-Cu₂O-PdO) slags, relevant to the processes, were investigated using Fourier-transform infrared (FTIR) spectrometry. Deconvolution of the FTIR spectra was carried out to calculate the relative abundance of different silicate structural units (Qⁿ), the overall degree of polymerization (DOP) of the slags and the oxygen speciation in the FCS slags. It was observed that, for the slag investigated, the relative intensity of both the high-frequency band ≈ 1100 cm⁻¹ (Q³) and low-frequency band ≈ 850 cm⁻¹ (Q⁰) were affected by Fe/SiO₂ ratio, basicity, temperature (T) and oxygen partial pressure (pO₂). The DOP and the average number of bridging oxygen (BO) were found to decrease with increasing both Fe/SiO₂ ratio and basicity. Improved semi-empirical equations were developed to relate the DOP of the slags with chemistry, process parameters and partitioning ratio (i.e., the ratio of the amount of element in the slag phase to metal phase, also known as distribution ratio) of Pd and Ge. Possible reactions, expressed as reactions between metal cations and silicate species, as a way to evaluate thermodynamic properties, are presented herein. Full article

Exergy analysis is one of the useful decision-support tools in assessing the environmental impact related to waste emissions from fossil fuel. This paper proposes a thermodynamic-based design to estimate the exergy quantity and losses during the recycling of copper and other valuable metals out of electronic waste (e-waste) through a secondary copper recycling process. The losses related to recycling, as well as the quality losses linked to metal and oxide dust, can be used as an index of the resource loss and the effectiveness of the selected recycling route. Process-based results are presented for the emission exergy of the major equipment used, which are namely a reduction furnace, an oxidation furnace, and fire-refining, electrorefining, and precious metal-refining (PMR) processes for two scenarios (secondary copper recycling with 50% and 30% waste printed circuit boards in the feed). The results of the work reveal that increasing the percentage of waste printed circuit boards (PCBs) in the feed will lead to an increase in the exergy emission of CO₂. The variation of the exergy loss for all of the process units involved in the e-waste treatment process illustrated that the oxidation stage is the key contributor to exergy loss, followed by reduction and fire refining. The results also suggest that a fundamental variation of the emission refining through a secondary copper recycling process is necessary for e-waste treatment. Full article