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Transitioning from a traditional linear economy to a circular economy occurs at the micro-level system, encompassing products and companies, which should be monitored. For metals, recycled content as an input-side indicator of recycling quantifies the ratio of metal scrap consumed during production and fabrication. However, conventional methodology struggles to evaluate recycled content uniquely due to the ambiguous classification of new scrap derived from industrial processes. Additionally, the input and output of new scrap between micro-level systems are often inadequately counted, causing inconsistencies in the recognition of secondary input between macro- and micro-level systems. This study introduces a refined classification for metal scrap, precisely distinguishing new scrap by its originating processes. Furthermore, we propose a novel perspective on new scrap, viewing it as a mixture of old scrap and primary raw materials, with only the portion of old scrap being considered secondary raw material. This stance navigates past the binary classification—whether new scrap should be classified as secondary—eliminating ambiguity and allowing for clear identification of secondary raw materials. The developed methodology ensures that all inputs of scrap are accounted for without leakage, and the recycled content of a specific metal is uniquely determined, maintaining consistency with macro-level systems. [ABSTRACT FROM AUTHOR]

As ASEAN countries, including Vietnam, approach the living standards of developed countries, their copper demand is set to rise. This study investigates Vietnam's copper stock and flow from 1995 to 2050, employing dynamic material flow analysis and five socioeconomic pathway scenarios (SSPs). Based on this, the secondary copper reserves of Vietnam were assessed. The results showed that the domestic copper demand is expected to grow to 526–1062 kt, resulting in a rapid increase in scrap generation. In 2022, Vietnam's secondary copper reserves stood at 2.2 Mt and are projected to reach 6.8–8.6 Mt by 2050 under the SSP2 scenario. This corresponds to 3.6–4.6 times the 1.8 Mt primary copper reserve of Vietnam. However, these primary and secondary reserves cannot meet the cumulated demand by 2050. On the other hand, a large amount of copper, 8.9 Mt to 10 Mt, will become difficult-to-recover resources, such as waste in landfill sites, dissipated materials, or mixed metal loss. To promote the sustainable use of copper in Vietnam, we recommend increased geological expedition and mining investment, and improved waste management systems related to secondary resources. [ABSTRACT FROM AUTHOR]

Currently green hydrogen production is attracting global attention. In this context, sustainable hydrogen production processes have been explored by using variety of materials and methods. Generation of hydrogen without CO 2 emissions is the key for carbon-free energy economy in future. Enormous amounts of scrap iron, metallurgical wastes and ferrous metals are produced in industrial processes. In this work, the reaction between metal scrap and steam is studied for hydrogen production. The scrap materials are loaded in a packed-bed reactor to produce green hydrogen by water splitting at high temperatures. This method produced 500 mL of green H 2 per gram of scrap material at 1150 °C with a conversion efficiency of about 94%. This is a potential method to utilize the scrap metals for large scale production of green hydrogen without carbon emissions. [Display omitted] • Process of hydrogen production using metal scrap. • Generation of 500 mL of green hydrogen from 1 g of waste-scrap material. • Scalable process for extracting hydrogen from metal-waste. • Maximum hydrogen concentration measured is 924 μL of hydrogen per mL of outlet gas. [ABSTRACT FROM AUTHOR]

As ASEAN countries, including Vietnam, approach the living standards of developed countries, their copper demand is set to rise. This study investigates Vietnam’s copper stock and flow from 1995 to 2050, employing dynamic material flow analysis and five socioeconomic pathway scenarios (SSPs). Based on this, the secondary copper reserves of Vietnam were assessed. The results showed that the domestic copper demand is expected to grow to 526–1062 kt, resulting in a rapid increase in scrap generation. In 2022, Vietnam’s secondary copper reserves stood at 2.2 Mt and are projected to reach 6.8–8.6 Mt by 2050 under the SSP2 scenario. This corresponds to 3.6–4.6 times the 1.8 Mt primary copper reserve of Vietnam. However, these primary and secondary reserves cannot meet the cumulated demand by 2050. On the other hand, a large amount of copper, 8.9 Mt to 10 Mt, will become difficult-to-recover resources, such as waste in landfill sites, dissipated materials, or mixed metal loss. To promote the sustainable use of copper in Vietnam, we recommend increased geological expedition and mining investment, and improved waste management systems related to secondary resources.

A ground breaking solar freshwater system has been developed, incorporating a photovoltaic (PV) heater and multiple stages. Extensive research was conducted to assess the system’s efficacy in improving freshwater production. Notably, the investigation revealed the presence of a 0.5 kg layer of Metal Scrap (Aluminium & Brass Scrap) at the bottom of the solar still’s down basin. The system utilizes solar rays and a direct current (DC) water heater to preheat the saltwater. In order to maximize freshwater production, specific surfaces were incorporated into the system design. These surfaces consist of a single glass lid positioned on the top and another at the bottom of two stacked trays. Their purpose is to efficiently collect condensation vapour, while minimizing resistance to condensation. Furthermore, an adjustable cooling water shower was employed to counter the excessive heat generated by the glass cover. The research focused on various factors such as the flow velocity of the cooling water shower, the impact of the heater, and the depth of water in the lower basin. It was found out that solar radiation, metal scrap, and heater input heat exhibited a proportional relationship within this innovative solar desalination system. Impressively, the Photovoltaic Heater (PVH) achieved a remarkable production of up to 15 liters per day of distilled water. Both mathematical modelling and experimental approaches were employed to determine the maximum of attainable cooling water flow rate, the total freshwater yield, and the effectiveness of PVH under ideal conditions. This comprehensive study provides valuable insights into the system’s performance and its potential for efficient freshwater production. [ABSTRACT FROM AUTHOR]

Particle-reinforced aluminium matrix composites (AMC) with a high-volume fraction of ceramic reinforcement (>30 vol.%) combine high specific strength and stiffness with good wear resistance and thermal stability, resulting in their increasing popularity in high-load applications, such as brake discs and bearings. It is hence assumed that AMC will accumulate as scrap in the near future. Appropriate recycling strategies must therefore be developed to maintain AMC's inherent properties. Melt-metallurgical recycling routes bear the danger of dissolving the ceramic reinforcement in the liquid metallic matrix and contaminating primary melts or forming intermetallic phases in secondary melts. Here, a solid-state AMC recycling route with crushing and sintering is investigated, wherein all steps are carried out below the solidification temperature of the aluminium matrix. A sintered primary AMC is mechanically converted into a particulate/powdery secondary raw AMC in coarse, medium, and milled quality (i.e., with d ≈ 7–12 mm, d ≈ 3–7 mm, and d < 300 µm) and subsequently resistance heating sintered to a secondary AMC under a variation of the sintering pressure. The two AMC generations are analysed and discussed regarding their microstructure and mechanical properties. Since the secondary AMC show reduced the mechanical strength, the fracture surfaces are analysed, revealing iron contaminations from the mechanical processing. [ABSTRACT FROM AUTHOR]

Metal recycling is an effective way to deal with the abundance of scrap metal such as drink can, scrap iron and others. Metal recycling skill is needed by the community especially in the youth to help reduce the amount of scrap metals in the environment and to develop a new creative and innovative industry, however the community doesn’t have the skills needed and have never gotten the training on metal recycling. Therefore, in the community service acticity of the Materials and Metalurgical Engineering Study Program, ITK, it was given metal recycling skill (aluminum) for the community. The metal recycling skill training was held in Kalimantan Institute of Technology campus, Balikpapan, East Kalimantan. The training was attended by 15 people from the community. The training was held by conducting presentation, practice, and discussion. The qualitative analysis results (from observation and discussion result) showed that all participant felt getting new knowledge and skill, that is the metal recycling skill.

We study the processes and mechanisms of electron-beam melting (EBM) used in the production of high-purity metals. We formulate the requirements that should be imposed on the EBM parameters for the production of high-quality materials and proposed some optimal modes. [ABSTRACT FROM AUTHOR]

Highlights • The idea of using eddy currents to recover nonferrous metallic particles dates back to 1889. • Modern-day eddy current separators are efficient at recovering nonferrous metallic particles. • A theoretical background for analytical models is reviewed and discussed. • Limitations of current designs and new designs and applications are presented. Abstract Eddy current separation (ECS) is a process used throughout the scrap recycling industry for sorting nonferrous metals from other nonmetallic fluff. The mechanism is based on the principle that a time-varying magnetic field will induce electrical current to flow throughout the body of a conductive particle. This current then reacts to the applied magnetic field by exhibiting a pronounced force of deflection, thereby separating the materials. The process is remarkably efficient and environmentally friendly, making it essential to the growth and sustainability of the metal recycling industry. In this review, we aim to summarize the available literature on eddy current separators for recovery of nonferrous metals. Although several different designs of eddy current separators have been examined through the years, the most common in use today remains the belt-driven rotary drum design. Limitations of the belt-driven rotary drum design are discussed as well as potential new designs and new applications for eddy current separators. [ABSTRACT FROM AUTHOR]

Eddy-current separation is most often method used for the recovery of non-ferrous metals (Al, Cu, Zn, Pb) from solid wastes and also for separating non-ferrous metals from each other. The feed material comes to rotary drum and magnetic field by belt conveyer. The changing magnetic field induce eddy currents in conductive (metallic) particles. Because interaction between this currents and the magnetic field electrodynamic forces will act on conductive particles. Therefore the trajectories of conductive particles will be different from the trajectories of the non-conductive ones. Separation is a result of the combined actions of several forces (electrodynamic, gravitational and frictional). The paper presents results of aluminium recovery from mixture of metallic particles in eddy current separator. Testing were conducted under field condition. Results shows that is possible achieve recovery of 99 % and concentrate quality of 89 % of aluminium (the paper is published in Croatian).

In this study, geochemical, geospatial and exposure risk analyses were combined to assess the ecological vulnerability to toxic metals of topsoil around a metal recycling factory in southwestern Nigeria. Samples of topsoil around the facility were collected and analyzed for Cd, Zn, Pb and Fe by atomic absorption spectrophotometer. Enrichment factors (EF) with reference to local background values were calculated to assess the extent of contamination of the topsoil. EF values showed that topsoil was moderately enriched with Cd and Zn, while the Pb level in the topsoil was close to the reference value. Spatial mapping of concentrations indicated potential ecological hazard (PEH) from Cd at the N, SW and SE of the factory; isolated zones of Pb within PEH at the N and SE, whereas 70 % of the area displayed Zn concentrations at the PEH threshold. Mapping of EF showed a differential pattern of EF levels, with isolated hotspots of extreme and high enrichments at the N and S, respectively. Ninety-nine percent of the studied topsoil around the factor was minimally enriched in Pb, while EF mapping indicated minimal to moderate enrichment. The immediate surroundings of the factory are moderately enriched in Zn, while the extreme N was minimally enriched. Exposure risk assessment gives an estimated hazard index that implies no current risk of health hazards for humans. However, it is advised that an effective pollution control should be implemented, because there is the possibility of increased hazard as production continues. [ABSTRACT FROM AUTHOR]

[Display omitted] • A feasible and green method is developed to prepare novel MOF composite beads. • Entanglement networks and hydrogen-bond interactions are generated by PEI in B-MOF. • B-MOF exhibited high adsorption capacity (334.68 mg.g−1) and excellent reusability. • An efficient process for the recovery of Pd from industrial waste is established. • Inner-sphere complexation and electrostatic attraction are the main mechanisms. Separation and recovery of palladium from industrial waste is an environmental way to utilize the valuable secondary resources. Metal-organic framework (MOF) has a great potential for the adsorption of Pd(Ⅱ) from aqueous solutions, but the tiny powder form of MOF restricts its practical applications. In this work, a feasible and green method is developed to prepare novel MOF composite beads (B-MOF) with a stable cross-linked network. The adsorption performance of B-MOF for Pd(Ⅱ) was evaluated in acidic solutions. Comprehensive characterization results show that the structure of B-MOF is stable throughout the adsorption process. At pH 3.0, the adsorption capacity of Pd(Ⅱ) on B-MOF was high up to 334.68 mg.g−1, exhibiting superiority to most of the other congeneric adsorbents. The adsorption behavior accorded with the pseudo-second-order kinetic model and the Langmuir adsorption isotherm, which was a spontaneous and endothermic chemisorption process. Moreover, the adsorption performance of B-MOF persisted almost unchanged even after 12 regeneration cycles. B-MOF also demonstrated high selectivity to Pd(Ⅱ) in the presence of interfering ions, including Na(Ⅰ), K(Ⅰ), Ni(Ⅱ), Mg(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Co(Ⅱ), Ca(Ⅱ) and Al(III). Mechanism studies reveal that Pd(Ⅱ) can be adsorbed on B-MOF by the inner-sphere complexation to Zr-nodes and the electrostatic attraction with protonated amine groups. The recovery of Pd from a real industrial waste was successfully achieved with a recovery rate of 92.5 %. This study provides an effective method to improve the practicability of MOF-based materials and may open a new way for the disposal of industrial waste containing palladium. [ABSTRACT FROM AUTHOR]

The processing of liquid steelmaking slags to obtain a commercial product with specified properties and maximum iron extraction is considered. The performance of existing systems for liquid-phase reduction of the metal from slag and methods of liquid-slag processing is compared. Prototype equipment for slag processing is developed and tested at OAO OMK-Stal' (Vyksa) on liquid electrofurnace slag and ladle (refining) slag. [ABSTRACT FROM AUTHOR]

The numerous accidents occurred in companies that melt scrap metals have shown that the hazard caused by the presence of radioactive materials - or 'orphan sources' - may have serious consequences on standard production, with great economic and social damage. Italian Legislative Decree No. 100/11 establishes the skills required for the safe management of scrap metals in the whole production cycle, thus requiring the involvement of experts in radiation protection. The paper details the procedures that shall be implemented in the companies that melt scrap metals. Said procedures involve several professional roles: managers, department heads and occupational physicians. The paper describes the general characteristics of the instruments used, staff training programs and the experience gained in 15 years of activity. [ABSTRACT FROM AUTHOR]

Recycling gives the industry a means to create treasure out of trash. Recycling of used metals in the form of scrap or secondary articles has assumed significance, especially in developing countries like India where reprocessing to recover metal is needed to meet the raw material deficit as well as conservation of minerals. For India, where labour is cheap, the metal and scrap recycling industry holds the potential of being a big employment generator and contributes to growth of mineral-based industrial activity. An overview on importance of recycling of metal scraps, its process, advantages, legal aspects, international scenario, etc., to conserve the domestic mineral resources for the future has been attempted in this paper. [ABSTRACT FROM AUTHOR]

A mathematical model has been developed and an algorithm of calculation of heat- and mass-transfer processes in heating and melting of metal scrap in an electric-arc steel-making furnace has been created. The results of numerical modeling of the dynamics of melting of metal scrap in this furnace have been given. [ABSTRACT FROM AUTHOR]

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[Display omitted] • Colourful residues found in Persepolis were deeply investigated for the first time. • Malachite with green earth represent an evidence of a mixture ready to use. • Red and yellow lumps of pigments are related with Fe-deposits located in Fars area. • Evidence of Egyptian blue manufacturing from bronze scarp and diopside trace. • Confirming of local workshops production according to archaeologists' hypothesis. The microstructure and chemical composition of blue and green pellets, coloured lump pigments and a metal scrap excavated in Persepolis West (Fars, Iran), by the Iranian-Italian Joint Archaeological Mission in Fars in 2008–09, were investigated to clarify their origin and production techniques. The Persepolis West urban area has its eastern limit about five hundred meters away from the Persepolis Terrace and extends for about 1 km in a westward direction. Due to the presence in this area of various kilns and other remains, the existence of a craft zone connected with the construction of imperial and élite buildings in Persepolis was proposed. The colourful residues were submitted to integrated investigations using portable X-ray fluorescence spectrometry, digital and polarized light microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray diffraction, ATR-FTIR and Raman spectroscopy. The integrated analyses allowed to identify azurite, malachite, Egyptian blue, glauconite, yellow and red ochre with hematite, magnetite and goethite. Proteinaceous material was detected only in one red lump. These pigments are in accordance with the palette used to paint the palaces of the Persepolis Terrace, thus supporting the hypothesis that in Persepolis West craft zone, there was a laboratory for production of pigments. The microscopic features of the lumps and their peculiar shape confirmed a local manufacturing process. Moreover, the diopside presence related to the Egyptian blue production, as well as the discovery of a bronze scrap with a crust of Egyptian blue also suggested that this pigment was manufactured locally. [ABSTRACT FROM AUTHOR]

• International trade of metal scrap relocates their embodied alloying elements. • Potential alloying elements leakage in scrap export may hamper circular economy. • An alloying elements composition database for scrap metals established. • An explorative case study for denmark confirms necessity for further research. Since metals are often used in alloyed forms, proper management and efficient recycling of metal scrap is key to sustainable management of those alloying metals as well. Previous studies on the trade of metals and metal containing products focused mainly on the carrying major metals themselves, however, the quantity and type of their embodied alloying elements remain rarely investigated. In this paper, we aim to address this knowledge gap by compiling an alloying element composition database for scrap of three bulk metals (iron and steel, aluminum, and copper), and using Denmark, a typical industrialized country with a high share of metal scrap export, as an example. Our results show that most alloying elements embodied in bulk metal scrap exported from Denmark depict a fluctuating yet overall increasing pattern from 1988 to 2017. While alloying elements embodied in steel scrap such as chromium and nickel and the construction sector contribute the most to the total embodied alloying elements, other alloying elements such as cobalt, bismuth, vanadium, titanium, and niobium with a lower amount yet a high market value and criticality status deserve a closer look as well. We conclude that further investigation on how the trade of metal scrap affect the recycling pathways and efficiencies of alloying elements are needed to support discussion on global and regional resource management and circular economy strategies. [ABSTRACT FROM AUTHOR]