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During the treatment of copper anode slime (CAS) under an air atmosphere, several aspects of the interactions of its main components (CuAgSe, Cu2−xSeyS1−y, Ag3AuSe2) with oxygen were described in Part I. As a comparative and complementary study, this work deals with the thermal behavior of CAS under air in the presence of polyvinyl chloride (PVC) b...
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Due to their unique properties, organosols of silver nanoparticles are widely used in optical and semiconductor devices, to produce electrically and thermally conductive films, as catalysts, antibacterial materials, etc. This work proposes a simple and highly productive method for the preparation of silver organosols, which have a metal concentrati...
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... More recent studies have recognised the unrecovered value in anode slimes and identified potential routes for their recovery (Zeng et al., 2022(Zeng et al., , 2023. Some of these studies have emphasised the importance of slimes characterisation for development of recovery methodologies (Kanari et al., 2019(Kanari et al., , 2020Khakmardan et al., 2023). Techniques used in these studies have ranged from traditional methods like backscattered scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). ...
Together with silver (Ag) and gold (Au), which are almost always recovered, the impurity elements, arsenic (As), antimony (Sb), bismuth (Bi), tin (Sn), lead (Pb), selenium (Se) and tellurium (Te) are major components of anode slimes, a by-product of the electrorefining of impure copper. The Olympic Dam electrorefinery, South Australia, generates raw slimes (∼30 % Cu, 5–10 % Ag, 0.5–1 % Au, 3–4 % Bi, ∼2–3 % Sb, and 5–6 % As), which subsequently undergo decopperisation and then pH-neutralisation. Decopperisation involves treatment with steam and acid at 90 °C, giving a slime that contains ∼ 1 % Cu, 8–17 % Ag, ∼2% Au, ∼7% Bi, ∼4–5 % Sb, and ∼ 3 % As. pH-neutralisation is achieved by addition of NaOH and is the final step prior to cyanidation and precious metal recovery. Bulk chemical compositions, gross morphology and particle size distributions are complemented by high-magnification backscatter imaging and energy-dispersive X-ray analysis of individual particles in raw, decopperised, and pH-neutralised anode slimes. In a first micron-to-nanoscale approach, we use electron backscatter diffraction mapping to assess the crystallinity of individual component phases and a scanning transmission electron microscopy study on micron-sized slices extracted in-situ to confirm the crystal structure of a conspicuous BiAsO4 phase as rooseveltite. The results establish an in-depth understanding of element deportments in slimes and their evolution during sequential stages of treatment. Characterisation studies for Te, Se, Sb, Bi, and As are essential prerequisites for any design of metallurgical circuits for by-product recovery from anode slimes and/or electrolyte. This study aims to demonstrate that complementary cutting-edge microanalytical techniques widely used in mineralogy provide a level of detail essential when considering refinery slimes as a new source of critical commodities.
... Kanari et al. [9][10][11][12] reported their characterization results of chromite concentrate [9], copper anode slime [10,12] and alkali ferrates synthesized from industrial ferrous sulfate [11]. Their characterization consists of inductively coupled plasma atomic emission spectroscopy (ICP-AES), SEM-EDS and X-ray diffraction in order to extract information on the chemical composition, morphology and mineralogical composition of their products prepared under different conditions. ...
... Kanari et al. [9][10][11][12] reported their characterization results of chromite concentrate [9], copper anode slime [10,12] and alkali ferrates synthesized from industrial ferrous sulfate [11]. Their characterization consists of inductively coupled plasma atomic emission spectroscopy (ICP-AES), SEM-EDS and X-ray diffraction in order to extract information on the chemical composition, morphology and mineralogical composition of their products prepared under different conditions. ...
The Special Issue aimed to provide a forum for scientists and engineers to share and discuss their pioneering/original findings or insightful reviews on the “Characterization and Processing of Complex Materials” [...]
... In addition, along with the depletion of raw materials rich in valuable substances, the quantity of solid residues generated will increase in the future. However, their content in elements considered critical and strategic [1][2][3] often greatly exceeds that found in natural deposits. Other by-products are almost pure and they are used for the synthesis of new materials [4,5] utilized for water and wastewater treatment. ...
... Other by-products are almost pure and they are used for the synthesis of new materials [4,5] utilized for water and wastewater treatment. Another source of metals of interest are end-of-life materials, such as electrical waste and electronic equipment, known as WEEE, representing a vast and constantly increasing waste stream [3]. In the dynamics of a circular economy, sustainable development, environmental and societal imperatives, as well as the shortage of natural deposits rich in metals, waste material is progressively becoming an attractive target for research orientation. ...
... Four types of gem-imitating glasses were prepared by the elemental substitution of praseodymium, neodymium and chromium elements present in rare-earth glass and examined by combining refractive index, density, spectral characteristics and color parameters. All imitation gemstone glasses are transparent, with a refractive index higher than 1.5 and a density up to 2.6 g/cm 3 . The comprehensive performance of the prepared imitation gemstone glasses can be found in the corresponding natural gemstones, which has a certain practical value. ...
This Special Issue (SI) offered the opportunity to present the latest scientific developments and findings in the field of processing of end-of-life materials and solid industrial wastes. Due to the large quantity of wastes generated and to their complex elemental and mineralogical composition, the approaches, methods and processes proposed for their decontamination, energy beneficiation and high-added-value metal recovery are complex and diverse. Some transversal research investigations using wastes as remediation agents and for synthesis of new materials were also included in the SI. After a brief introduction, the main scientific contributions and findings of each article published in the SI are summarized.
... Selenium is currently recovered from anode slimes by hydrometallurgical and pyrometallurgical processes [5,15,16]. Although the traditional pyrometallurgical method recovers selenium effectively, there are difficulties relating to high energy costs and increasingly strict environmental regulations [1,3,6,17,18]. ...
... Wt (%) Selenium is commonly present in copper anodes as copper selenide (Cu 2 Se), but in anode slimes, it occurs in various phases of Ag-Cu selenides [2,4,12,[14][15][16]21]. Selenide is usually one of the main carriers of silver in anode slimes, this is because the silver in the solid copper matrix and the dissolved silver during electrorefining react with Cu 2 Se to form Ag-Cu selenide compounds. ...
About 90% of selenium is obtained from treating copper anode slimes, which are a by-product of copper electrorefining. Selenium has been traditionally obtained by the pyrometallurgic treatment of anode slimes, which has been effective in recovery. However, in pyrometallurgical processes, there are increasingly strict environmental regulations. Hydrometallurgical treatments have been proposed to totally or partially replace conventional methods, some of which are in the developmental stage, while others are being used at the industrial scale. The selenium present in anode slimes is in the form of silver and copper selenides. This article proposes a hydrometallurgy alternative to recover selenium from decopperized anode slimes generated by a copper electrorefining plant in Chile by an alkaline-oxidizing leaching media (ClO−/OH−). The Taguchi experimental design was used to assess the effects of temperature, reagent concentration, and pH over time. The results indicated that the optimal selenium dissolution of 90% was achieved at pH 11.5, 45 °C, and 0.54 M of ClO−. According to the SEM/EDX characterization of the solid leaching residue, the undissolved percentage of selenium is due to the generation of a layer of AgCl around the selenium particles that hinders the effective diffusion of the reagent.
... As reported by Ma et al. [8], the chlorine causes high temperature corrosion and low efficiency in waste-to-energy processing plants. Note that other potentially polluting substances contained in plastic are the bromine-containing flame retardants still used widely to meet the flammability standards of products [9]. Several recent scientific studies addressing the diverse aspects of plastics containing PVC and halogenated flame retardants were reported in the scientific journal Materials [10][11][12][13][14][15]. ...
... It is designated as W-PVC. A sample of pure PVC [9] with an average mean particle size of 100 µm was also used for the comparison purpose of the thermal behavior; it is noted as P-PVC. The hematite sample, having micrometric particles and with a chemical purity higher than 99.5% Fe 2 O 3 , was procured from Merck Chemicals (Eurolab, Fontenay-sous-Bois, France). ...
... As revealed previously [9] by SEM-EDS analysis, the pure PVC (P-PVC) sample is composed of chlorine and carbon (hydrogen not analyzed by this technique). As aforementioned, the PVC resin has the raw chemical formula (C 2 H 3 Cl) n but other chemicals are added to enhance the functional properties of the bearing PVC materials. ...
The mass production of synthetic plastics began in the last century and today they have become one of the most abundant man-made materials. The disposal or the beneficiation of end-of-life plastics represent a great challenge for society especially in the case of polyvinyl chloride (PVC). This study is focused on the use of PVC waste as a useful agent for the direct reduction of hematite (Fe2O3) after a thermal treatment at 300 °C for removing the chlorine contained in PVC. Thermal reduction tests were conducted from 600 °C to 1100 °C with (Fe2O3 + PVC + clay) pellet mixtures in which clay was used as plasticizing and binder agent of the pellets. The starting samples and treatment residues were analyzed by scanning electron microscopy through energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD) to monitor the chemical behavior and reactivity of the pellet constituents during their thermal treatment. The stepwise reduction of hematite up to metallic iron was achieved at temperatures approaching 1000 °C, confirming the capability of using PVC waste for the direct reduction of iron oxides.
The increase in electronics production has resulted in the massive generation of electronic waste. Integrated circuits are crucial to printed circuit boards and must be considered for valuable material recycling. The complex structure of ICs comprises metals tightly bound in the epoxy resin (Si ~ 92.8%, Br ~ 3.8%), thus, making metal recycling a challenge. Pyrolysis was studied to decompose the organic fraction on relatively large-sized ICs without size reduction, which facilitated metal liberation. Based on the thermogravimetric analysis, 90% (by mass) of the organic matter is decomposed in the temperature range of 300–700°C, and overall, the pyrolysis activation energy is determined as ~ 190 kJ/mol. The pyrolysis residue was sieved to obtain a coarser metal-rich fraction and finer non-metal-rich fraction, which comprised 20–24 wt.% and 63–69 wt.% of the pyrolysis product, respectively. In the coarser fraction, the metal recoveries obtained are Cu ~ 96.9%, Fe ~ 89%, Ni ~ 64.6%, Pb ~ 57.1%, and Ag ~ 33%. The undersized fraction comprises mainly Si values (87%) with minor metals, especially the Ag values ~ 2.2%. The undersized fraction was leached using HNO3 and Na2S2O3 to recover minor elements, and maximum Ag dissolution was observed as ~ 96.8% and 89.7%, respectively.
