Search

Progressing towards circular economy requires smarter and more efficient use of energy and resources. Laser beam can be efficient and flexible tool for melting different metals, commonly used in cladding and additive manufacturing (AM) with a wire and powder feedstock. As an alternative, feedstock in the form of plates and sheets can be used for cladding to achieve corrosion resistant surfaces. Compared to powder or wire, plates are easier to process, less costly to use, and may come as scrap metal. This leads to smarter and more efficient resource utilization. However, processing plates in such way is not mature and requires more in-depth investigation to be competitive with well-established methods. In this work, 2.0 mm thick 316L stainless steel plates were remelted by a high-power fibre laser beam for cladding on carbon steel substrates. It was compared to the conventional cold metal transfer (CMT) welding-based arc cladding which is frequently used due to a low heat input. In the first phase, different defocusing distances were studied to understand the laser remelting process capabilities to optimize the productivity. It was found that a highly defocused laser beam provided unstable melt pool conditions with low track quality. Compared to CMT, the laser remelting provided enhanced productivity, reduced heat input by 50% per pass, and lower distortions. Microhardness testing showed an increase in hardness in the intermediate layer towards the fusion line due to carbon diffusion. Despite a higher delta ferrite formation in laser-remelted tracks, a comparable corrosion protection to CMT was observed. The proposed method is promising for reducing CO2 emissions with respect to reusing scrap metal in the form of plates or use of ordinary plates instead of filler wires which opens possibilities for further enhancements. [ABSTRACT FROM AUTHOR]

The article "Black Metallurgists and the Making of the Industrial Revolution" by Jenny Bulstrode explores the contribution of Black metallurgists in Jamaica to the development of ironworking techniques. It discusses the translation of technology between the sugar and iron industries and the historical connections between Jamaica and England. The article challenges conventional narratives of technological development by highlighting the contributions of enslaved African peoples and emphasizes the importance of diverse perspectives and critical engagement with historical sources. It also addresses the ongoing impact of anti-Black formulations in history-writing and the need to recognize historical conditions of conquest and enslavement. [Extracted from the article]

In this study, we propose a transfer learning-based classification model for identifying scrap metal using an augmented training dataset consisting of laser-induced breakdown spectroscopy (LIBS) measurement of standard reference material (SRMs) samples, considering varying experimental setups and environmental conditions. LIBS provides unique spectra for identifying unknown samples without complicated sample preparation. Thus, LIBS systems combined with machine learning methods have been actively studied for industrial applications such as scrap metal recycling. However, in machine learning models, a training set of the used samples may not cover the diversity of the scrap metal encountered in field measurements. Moreover, differences in experimental configuration, where laboratory standards and real samples are analyzed in situ, may lead to a wider gap in the distribution of training and test sets, dramatically reducing the performance of the LIBS-based fast classification system for real samples. To address these challenges, we propose a two-step Aug2Tran model. First, we augment the SRM dataset by synthesizing spectra of unobserved types through attenuation of dominant peaks corresponding to sample composition and generating spectra depending on the target sample using a generative adversarial network. Second, we used the augmented SRM dataset to build a robust real-time classification model with a convolutional neural network, which is further customized for the target scrap metal with limited measurements through transfer learning. For evaluation, SRMs of five representative metal types, including aluminum, copper, iron, stainless steel, and brass, are measured with a typical setup to form the SRM dataset. For testing, scrap metal from actual industrial fields is experimented with three different configurations, resulting in eight different test datasets. The experimental results show that the proposed scheme produces an average classification accuracy of 98.25% for the three experimental conditions, as high as the results of the conventional scheme with three separately trained and executed models. Additionally, the proposed model improves the classification accuracy of arbitrarily shaped static or moving samples with various surface contaminations and compositions, and even for differing ranges of charted intensities and wavelengths. Therefore, the proposed Aug2Tran model can be used as a systematic model for scrap metal classification with generalizability and ease of implementation. Graphical Abstract This is a visual representation of the abstract. [ABSTRACT FROM AUTHOR]

Metal sorting is the first step in scrap metal recycling. The traditional magnetic separation method can classify ferromagnetic metals, but it is not applicable to some nonmagnetic metals with higher value. To address this situation, we propose an eddy current testing (ECT) technology-based method for classifying nonmagnetic metals. In this study, a triple-coil electromagnetic sensor, which works as two coil pairs, is tested. By analyzing the physical model of the sensor, a feature related to the conductivity of the sample under test is obtained as the difference in the tangent of the impedance changes in the two coil pairs. Additionally, we derive a linear relationship between this feature and the lift-off height, which is verified experimentally and will help to solve the classification error caused by the variation in the lift-off height. In addition, we find that the excitation frequency does not affect this linear feature. Moreover, in this study, the spectrum scanning method is converted into a single-frequency measurement, and the time consumption is greatly reduced, which improves the efficiency of the real-time metal classification system. [ABSTRACT FROM AUTHOR]

This pilot study addresses the analytical characterisation of 26 well‐known bronze objects of the Early and Middle Bronze Age of Central and Northern Europe. Besides swords and axes of the hoards from Apa, Téglás and Hajdúsámson, the investigation includes the famous Sky Disc and its accompanying finds from the Nebra hoard and several full‐hilted swords from Period I in Denmark. In contrast to former publications, the isotopic systematics of lead, tin and copper are the focus of the present investigation. With a combined approach, we try to relate the typologically closely linked or otherwise related artefacts with chemical and isotopic proxies by identifying mixing scenarios. The results demonstrate that artefacts from different locations are most likely not directly linked, but mixing lines across isotope systems suggest a production of the items from common sources by mixing of bronze batches (e.g., bronze ingots), which were probably disseminated between 1600 and 1500 bce. This helps to correlate objects of different locations with each other and to draw conclusions upon typological and cultural connections. Isotopic and chemical correlations of objects within the individual hoards, on the other hand, allow reconstructions of metallurgical practices in single workshops, which, for example, implies recycling of metal scrap. [ABSTRACT FROM AUTHOR]

A radioactive source that is not under regulatory control, either because it has never been under regulatory control or because it has been abandoned, lost, misplaced, stolen, or otherwise transferred without proper authorization, is considered an orphan source. Orphan sources are usually gathered as scrap metal because of their heavy metallic containers. Melting an orphan source with scrap metal produces contaminated recycled metal and waste; the consequences will be extremely serious for humans and the environment, affecting the economy and social stability. In this paper, we propose and develop an Internet of Radiation Sensor System (IoRSS) to detect radioactive sources out of regulatory control in scrap metal recycling and production facilities. It is a complete IoT system consisting of a network of wirelessly connected radiometric devices that optimizes the detection, localization, and identification of radioactive sources by integrating data from multiple portable radiation detectors. The proposed IoRSS system creates a robust and flexible network architecture along with advanced data fusion algorithms that combine information from many detectors. The IoRSS system provides advanced search and monitoring capabilities in a large coverage area and in difficult operational environments. [ABSTRACT FROM AUTHOR]

Dual-energy X-ray transmission analysis technology recycles scrap metal by identifying material types. In order to solve the problems that the identification result is greatly affected by the metal thickness and the range of metal thickness can be recognized is small, a metal identification method based on outliers is proposed based on the curve fitting method. The fitting curves based on high and low energy T-values are used to reduce the influence of thickness factor on the correlation of fitting curves, and the problem that the thick metal cannot be identified is solved. Outliers judgement is introduced to improve the accuracy of recognition. The identification experiments of metal aluminum and metal copper with different thicknesses are carried out. The results show that the T-value fitting identification algorithm based on outliers judgment has a better identification effect on aluminum and copper with different thicknesses. Compared with the traditional algorithm, the recognizable thickness range is increased to 90 mm and 40 mm respectively, which expands the range of metal thickness that can be sorted. [ABSTRACT FROM AUTHOR]

The use of electric arc furnaces is important in steelmaking, notably to recycle scrap steel, yet arc furnace is an unintentional source of persistent organic pollutants (POPs) such as chlorinated dioxins and furans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs) and brominated dioxins and furans (PBDD/Fs). Here, we review the level, profiles, influencing factors and formation mechanisms of such pollutants from arc furnaces of steelmaking plants. Comparison of various industrial sources shows that pollutant concentrations in the stack gas from the arc furnace in steelmaking plants are lower than that in the fly ash of all industrial sources. Preheating the scrap steel could increase the formation and emission of pollutants. The composition of raw materials is suggested to be an important influencing factor in pollutant formation. Air pollution control devices significantly reduce emissions of pollutants. [ABSTRACT FROM AUTHOR]

PRESENT-DAY ESTONIA WAS INCORPORATED into the Christian world in the early 13th century. This event brought dramatic changes to both its society and landscape, including the establishment of the first towns that soon played an important role in the emerging Hanseatic network, mediating trade between the West and East. These political and cultural changes are also reflected in the influences that reached Estonian towns, with the migration of craftspeople from German-speaking areas and Scandinavia; in particular, these innovations occurred in non-ferrous casting technology. The most important changes included the introduction of refractory crucibles, massive melting furnaces and more complex stone-casting moulds. Residue analysis showed evidence of highly specialised metalworking taking place. The large sample size revealed some unusual alloys, which are explained either by craftspeople's experimentation or by the reuse of scrap metal. By looking at the different crucible types and mould fragments, we are able to demonstrate how the mobile craftspeople were the carriers of both casting tools and knowledge inside the Hanseatic world. [ABSTRACT FROM AUTHOR]

• Experimental tests oriented to HTC process layout assessment. • A flash expansion step could improve plant performances. • The correct process scheme depends on waste biomass treated. • Sulfur emission per unit of energy produced significantly reduced. This paper contributes to the knowledge on waste biomass conversion processes occurring in the presence of hot compressed water. The experimental procedure detailed herein assesses different process schemes based on the low-temperature reaction known as hydrothermal carbonization. The performances of two lab-scale reactor configurations, with and without a downstream flash expansion step, were evaluated and compared. Each setup was tested with six different types of waste biomass. Fir, beech, and olive prunings are representative of lignocellulosic raw materials, while potato, pea, and carrot are representative of non-lignocellulosic wastes from processing in the local agro-food industry. The batch reactions (200 °C, water/solid = 7/1) were carried out for up to 120 min. The hydrochars were characterized by elemental composition, humidity, heating value, and mass and energy yields. The extent of difference between the results obtained for the two procedures varied significantly with the material treated. At a residence time of 30 min, the solid yields increased due to expansion, ranging from 10 to 36% for lignocellulosic material and 50 to 220% for agro-food industry scraps. The downstream flash expansion step causes an increase of the solid yields, especially for hydrochars from lignocellulosic materials, leading to higher energy recovered compared to the configuration without expansion. Lignocellulosic and agro-food wastes behaved dissimilarly, likely because of different hydrothermal reaction pathways. The additional expansion step can considerably increase the efficiency of energy recovery in full-scale plants, the extent of which depends on the biomass waste substrate used. [ABSTRACT FROM AUTHOR]

Achieving a U.S. circular economy would reduce environmental impacts and increase material independence. This article calculates maximum recycled contents (RCs) and recycling rates (RRs) in an independent U.S. steel sector, and estimates the potential to displace current imports with recycled scrap that is currently destined for landfill, hibernating stocks, or export (LHSE). A U.S. dynamic material flow analysis (1880–2100) is conducted to estimate annual steel consumption and scrap generation. The results are coupled with a linear optimization model that minimizes primary steel demand while satisfying the volumetric and compositional demands of new consumption. The compositional analysis examines only copper content because it is of greatest concern to recyclers. The best estimate is that the maximum independent RR is already constrained by copper contamination. Without interventions, this maximum RR will gradually decline throughout the century. The annual consumption to scrap availability ratio (C2SR) will decrease from around 1.4 today. Concurrently, the maximum RC rises but then plateaus below 75% as the RR falls. This highlights a conflict in the conditions for a circular economy: a C2SR approaching unity is a necessary condition for a high RC but leads to fewer opportunities for scrap contaminant dilution, which decreases the RR. Improved product design for recycling and deployment of scrap refining technologies will be needed to reach higher RCs. In 2017, the mass of U.S. scrap destined for LHSE exceeded direct steel imports. Domestic recycling of scrap exports alone could have displaced 36% of direct steel imports, reducing the U.S. deficit by $5.5 billion. [ABSTRACT FROM AUTHOR]

Scrap melting is of increasing interest to the metallurgical industry because it can significantly improve the production efficiency of electric arc furnace (EAF). In the present study, a water model experiment and theoretical analysis were used to investigate the effect of ice melting on the cooling effect of water bath under different ice shapes, ice sizes, bottom-blowing gas flow rates, side-blowing hot steam flow rates and top-blowing hot steam heights. Correspondingly, the melting rate of ice in water bath has also been studied. The results show that an increase in the original size of ice, the flow rate of bottom-blowing gas and the height of top-blowing hot steam, and a decrease in the flow rate of side-blowing hot steam, cause an increase in the cooling effect of ice melting on the bath. The melting rate of ice increases with increasing the flow rates of bottom-blowing gas and side-blowing hot steam, while an increase in the ice size and top-blowing hot steam height, prolongs the melting time of ice. The theoretical analysis results of ice melting process are in agreement with the results of the water model experiment. The results are beneficial to the optimization of the scrap melting process in the EAF. [ABSTRACT FROM AUTHOR]

Bac Ninh, a province adjacent to the Hanoi Capital Region of Vietnam, has long been renowned for its centuries-old craft villages. Today, Bac Ninh is becoming renowned for the toxic environments produced by its contemporary craft industries, such as the recycling of scrap metals and electronic waste. In this context, this paper considers how residents of a commune in peri-urban Hanoi perceive the cleanliness of their water, and how, accordingly, the social differentiation which has emerged since doi moi ('economic renovation') shapes their practices in procuring water they deem fit for household use. Analysis reveals a complicated picture of the ways in which households access water for everyday domestic use. In spite of the rollout of piped water infrastructure, we find residents relying on a mix of water sources, with private sources clearly preferred but access to those restricted by wealth. The results of these considerations offer glimpses both of the unintended consequences of doi moi and of how future events, including a diminishing supply of water and potential climate change impacts may affect residents of the expanding zones of peri-urban Vietnam. [ABSTRACT FROM AUTHOR]

We identified the key sectors of water resource use in China from the perspective of the water footprint to improve the use of water resources. The empirical results showed that there were six key sectors (including Crop Cultivation; Forestry; Livestock and Livestock Products; Fishery, Technical Services for Agriculture, Forestry, Livestock and Fishing; Other Food Products, and Scrap and Waste) for water consumption in China in 2015.We analyzed the use of green water, blue water, and grey water. These six sectors accounted for 66.15% of the total impact and 90.76% of the direct impact. Seven key sectors (the six sectors above plus Steel Processing)for the consumption of blue water in China can explain 59.70% of the total impact and 86.94% of the direct effect in 2015. Eight key sectors (Crop cultivation, Other food products, Scrap and Waste, Railway Freight Transport, Highway Freight and Passengers Transport, Water Freight and Passengers Transport, Pipeline Transport, and Health Services) responsible for the consumption of grey water in China in 2015 can explain 81.28% of the total impact and 95.73% of the direct impact. Therefore, the Chinese government should focus on the departments that manage water resources in these sectors when designing water-saving policies and improving water-use efficiency, such as promoting water-saving irrigation technology (including sprinkler irrigation and drip irrigation) in the agricultural sector. [ABSTRACT FROM AUTHOR]

The ever-increasing pressure on the steelmaking industry to reduce its environmental footprint and achieve higher performance ispushing the sector to continuous improvement of its processes, This new paradigm places steel scrap recycling-based manufacturingprocesses as one of the main alternatives for the steelmaking industry. Using heterogeneous recycled scrap mixtures for producing new andhigher performance steel products requires the use of well characterized scrap to reduce uncertainties of the process. However, ferrousscrap might be stored for long periods of time in scrap yards and be affected by atmospheric corrosion that degrades its initial quality. Inthis paper a new empirical methodology is proposed, which helps quantify the influence of this degradation phenomenon on the Electric ArcFurnace (EAF) performance based on the Value In Use (VIU) of the scrap. The equations proposed allow estimating the extra cost induced bydegradation of ferrous scrap material during storage periods. [ABSTRACT FROM AUTHOR]

• An integrated capture of scrap copper and electrodeposition process is proposed. • Capture mechanism and electrodeposition principles of process are clarified. • Purity palladium is deposited on the cathode under optimal conditions. • Environmental performance of this process is superior to traditional process. The coordinated treatment for two kinds of waste is an effective way to save energy and improve the recovery efficiency of resource. In worldwide, more than half of palladium is used to produce catalysts in automobile. However, with the increasing consumption of palladium, the scarcity of palladium resource is becoming prominent. This paper proposed an integrated process based on capture of copper scrap and electrodeposition process to recycle palladium in spent catalysis from automobile. The technological process mainly consisted of two procedures: capture of copper scrap with the purposes of enriching palladium and electrodeposition process with the purposes of separating and purifying palladium. Several highlights were summarized as follows: (i) a capture mechanism of palladium by copper scrap was studied by the calculation of surface thermodynamics and first principles. (ii) Optimum designs, parameter and product analysis were developed to guide industrial recycling. The appropriate parameters for capture of copper scrap are the melting temperature reached 1400 °C, adding 20% dosage of copper scrap and 2 of mass ratio of SiO 2 /Al 2 O 3 and for the electrodeposition process, nearly 100% of palladium was deposited on the cathode under 0.1 M concentration of HNO 3 , −0.042 V of electrodeposition potential and 25 °C reaction temperature with 9 h. (iii) This process overcame the shortages of traditional process and showed its efficiency and environmental performance. This study is significant for high-efficient, low-cost and environment-friendly recycling of valuable resource in spent catalysis from automobile. [ABSTRACT FROM AUTHOR]

Re-processing of scrap metal is one of the most important directions in the production of metals and alloys, as well as in the manufacture of various metal products. This activity is called the recycling. Recycling of scrap metal can be carried out, both by melting it, or by technology, currently gaining distribution in some metallurgical and engineering plants and which includes the processing of end-of-life metal products by hot forming. In this paper, the technology of recycling of ferrous metal scrap in the conditions of Akmola branch of JSC “Kazvtorchermet”, in order to obtain high-quality commercial product in the form of bars of circular cross-section or wire, is proposed. [ABSTRACT FROM AUTHOR]

Steelmaking is immersed on continuous development of new steel products with higher performance and lower environmental footprint. This new paradigm places scrap recycling steel manufacturing processes as one of the main alternatives for the steelmaking industry. Using heterogeneous recycled scrap mixtures for building new and more demanding steel products require the use of Hot briquetted Iron (HBI) to reduce process uncertainties process. However, HBI might be stored for long periods of time and is affected by atmospheric corrosion that degrades its initial quality. The present work proposes, for the first time, a methodology to empirically quantify the influence of this degradation phenomenon on the EAF performance by extending the calculation of the Value In Use considerating degradation processes. The proposed equations allow estimating the extra cost induced by HBI degradation during storing periods and help calculating a more precise scrap mixture to deal with the required technical and cost specifications. [ABSTRACT FROM AUTHOR]

Recycling of the cupronickel alloy scraps not only solves environmental related issues but also realizes the extraction of valuable metals and saves consumption of primary ore resources. Oxidative dissolution is a critical step for the recycling of valuable metal from the alloy scraps. In order to improve the dissolution kinetics and efficiency, a novel integrated electrochemical dissolution strategy for the sustainable recycling of the cupronickel alloy scraps was first developed, where the in-situ electro-generated reactive oxygen species (ROS) were employed as the indirect oxidative mediator. Much higher dissolved concentration of Ni, Zn, and Cu was reached by the present integrated strategy than that of the direct anodic dissolution process, which is attributed to the in-situ produced oxidative H 2 O 2 and ·OH via oxygen reduction reaction and electro-Fenton-like reaction, respectively. Moreover, the large quantity of ROS can be electro-generated, thus achieving high dissolved concentration, under the optimum condition with the preset potential of 0.3 V (vs. Ag/AgCl) or current density of 2.54 mA/cm2, respectively. This novel synergistic strategy may serve as a promising and cost-effective technique for the alloy scraps recycle and valuable metal extraction. Image 1 • Novel sustainable recycling of the cupronickel alloy scraps was proposed. • The mechanism of enhanced anodic dissolution of cupronickel alloy scraps was discussed. • Electro-generated reactive oxygen species is the main oxidative mediator. [ABSTRACT FROM AUTHOR]

Today, a significant portion of steel production worldwide is coming from recycling practices. It is inevitable that the smelting process during steel recycling operations is expensive and consumes a tremendous amount of energy. Therefore, hypothetically, direct reuse of steel materials without smelting can be environmentally and economically advantageous over recycling. In this article, an innovative recovering path for size-specific sheet metal scrap from the automobile industry is being proposed. The idea is to directly use the sizable sheet metal scrap generated from the car-body manufacturing process in the automobile industry to design and fabricate new metal facade systems for buildings' exteriors. An empirical case study was conducted, which is being presented to illustrate the benefits of reusing steel scrap over recycling with the same material using quantitative analysis. The required capital cost and energy consumption of generating a building metal facade system were evaluated. The results showed that reusing the sheet metal scrap over conventional recycling of the same material would lead to a cost reduction of approximately 40% (400 $/ton) and savings of approximately 67% (10 MJ/kg) of energy consumption. The tested concept promotes an innovative industrial symbiosis between the auto industry and the building and construction industry through creating a secondary closed supply-chain loop to achieve both circular economy and energy savings through adding value by design. [ABSTRACT FROM AUTHOR]

• Zinc recycling from Waelz oxide (treating EAFD) to increase sustainability of steelmaking industry. • Evaluation of sustainable technologies to recover zinc from unpurified secondary sources. • These techniques proven to solve limitations of Waelz oxide to be industrially processed as sole source. • Revision of most promising hydrometallurgical processes to produce high-purity ZnO and zinc metal. The steelmaking industry that uses electric arc furnaces to recycle steel scrap generates dust (EAFD) as its main residue. This waste must be treated to recycle some heavy metals for economic reasons and to prevent negative environmental impacts. It is formed basically by different metallic oxides with heterogeneous composition and size. The Waelz Kiln Technology is the most commonly used technology for this purpose, generating concentrates of Zn and Pb oxides (called Waelz oxides). The main component of Waelz oxides is zinc and nowadays the production of metallic zinc and high purity zinc oxide covers approximately 97 % of the zinc market. The impurities content in the Waelz oxides (different heavy metals, halogens, ...) makes impossible to use it as raw material to produce industrial high purity zinc oxide or in the electrolytic production of metallic zinc. At present, the Waelz oxides are blended with other purer raw materials. That supposes the unfeasibility of obtaining these products only through direct recycling EAFD. Therefore, the goal of this work is an in-depth study of the newest hydrometallurgical processes in order to achieve the production of these zinc products from Waelz oxides, showing their possibilities and limitations. [ABSTRACT FROM AUTHOR]

A review of environmental protection technologies for the integrated disposal of metallurgical industry waste is given. The results of studies on obtaining and determining the basic physicochemical properties of a new composition of self-curing, chemically resistant refractory mass are presented. The mass is comprised of industrial waste, including slag from electrothermal reduction of niobium pentoxide — crushed and purified fused Al2O3 (electrocorundum), and scrap of periclase-chromite articles. The mass has high chemical resistance, fire resistance, mechanical strength, hardness, wear resistance. [ABSTRACT FROM AUTHOR]

The Triple-bottom-line concept suggests that firms must consider the environmental and social impacts of their decisions, beside the economic aspects. Hence, the sustainability of the firms' operations can be reached. The purpose of this study is to develop a bi-objective, multi-product and multiperiod mixed-integer model for the operations planning of electrical-electronic waste (WEEE) recovery facilities, by considering social (workforce) constraints. Main objective is the minimization of net recycling and logistics costs offset by the profit earned by recovered material sales, and second objective is the maximization of hazardous materials recovery. Collection of used products from the specified regions is decided and the required machinehours, inventory and workforce decisions are made. Besides, both weightbased and unit-based WEEE recovery targets are separately considered, as a unique aspect. A sensitivity analysis is conducted with various scrap prices to understand operations planning in changing conditions. Results show that weight-based targets enhance recovery amounts. [ABSTRACT FROM AUTHOR]

Abstract A novel method was proposed in this study to recycle WC and Co from cemented carbide scraps by remelting and electrodissolution. WC was recrystallized and purified through melting process. The WC that embedded in alloy was independent of each other and thus was easily separated by electrodissolution. The effects of dissolving parameters were investigated, and the results indicated that the maximum dissolving rate was 0.045 g·h−1·cm−2 and the anodic passivation was not found even at 500 A·m−2 of current density. In addition, the temperature and concentration of HCl were irrelevant to the rate and the current efficiency of the electrolysis. The SEM showed that the final WC powder was 5–20 μm in particle size with a regular shape, and the Co was directly recycled from the cathode at the same time. Highlights • The cemented carbide scraps were remelted in VIM furnace after adding Co. • The WC grains recrystallized in the metal melt and the grain gap increased. • The electrodissolution was applied due to the WC keep a distance with each other. • A maximum dissolving rate of 0.045 g·h−1·cm−2 for Co was achieved. • The new WC powder was obtained from the anode and Co was deposited on the cathode. [ABSTRACT FROM AUTHOR]

• Design of new process of conversion of metallic waste to SnO 2 :Fe 3 O 4 nanocomposite. • Tuning of the composition of nanocomposite have been carried out. • SnO 2 :Fe 3 O 4 nanocomposite act as an efficient photocatalyst in UV and Visible range. Appropriate recycling of waste to reusable materials is much sought after in the scientific community to control the incessant rising pollution in environment due to insufficient management of waste materials. To address this issue, efforts were directed to obtain SnO 2 -Fe 3 O 4 nanocomposites from scrap tin plated steel and the use of these composites for the degradation of organic pollutant. We have demonstrated a novel, efficient and facile hydrometallurgy approach for the extraction of iron from waste tin plated steel containers found in plenty in the common waste generated in society. The extracted iron has further been utilized for the preparation of SnO 2 :Fe 3 O 4 nanocomposites with different compositions (SnO 2 :Fe 3 O 4 ratio of 93.2:6.8, 85:15, 58:42 and 40:60) using hydrothermal route. The photocatalytic activities of nanocomposite were determined spectroscopically using Rhodamine-B (RhB) as a model dye. Our results indicate that among all the composites with SnO 2 (85%):Fe 3 O 4 (15%) exhibits the best photocatalytic efficiency under UV light whereas the composition of SnO 2 (93.2%):Fe 3 O 4 (6.28%) is the most efficient in visible light. The above visible light efficiency was supported by density functional theory (DFT) studies which suggest a small amount of pure Fe is present at the Sn sites in the nanocomposite, leading to the reduction in the band gap of the nanocomposite and resulting in absorption in the visible range. Thus, in the present study, we have shown a process of conversion of waste to nanomaterials and its utilization for treatment of organic pollutants. [ABSTRACT FROM AUTHOR]

Highlights • Increasing product complexity metals causes mounting challenges to the scrap industry. • Inbound inspection and identification can be improved with technology solutions. • Sensor based technologies combined with physical diversion are optimal. • Large volume yards gain the most from technical interventions. Abstract Metals recycling is one of the oldest industries in the United States that now employs over 530,000 individuals. It has always played a significant role in the economy, supplied extensive goods and services, and the costs and benefits directly and/or indirectly extend worldwide. Improved efficiency in metals recycling is crucial to achieving a more circular economy; to enable this requires understanding how the industry operates and the challenges it must overcome. Increasing metal product diversity and design complexity combined with increased feed volumes has introduced recent additional challenges. This review explores the current status and state of the industry and examines potential technology solutions that address inbound inspection and material identification challenges. [ABSTRACT FROM AUTHOR]

Eddy current separation (ECS) is a process used throughout the scrap recycling industry for separating nonferrous metals from nonmetallic fluff. To date, however, the physical theory of ECS has generally been limited to empirical approximations and numerical simulations. We therefore introduce a simplified, two-dimensional model for ECS based on a cylindrical array of permanent, alternating magnets. The result is a Fourier-series expansion that describes the total magnetic field profile over all space. If the magnets are then rotated with constant angular velocity, the magnetic fields vary as a discrete series of sinusoidal harmonics, thereby inducing electrical eddy currents in nearby conductive particles. Force and torque calculations can then be used to predict the corresponding kinematic trajectories. [ABSTRACT FROM AUTHOR]

The paper describes an innovative technological solution for producing balls from scrap rail heads. The proposed method consists in performing the following operations: the side pressing of a rail head to increase shape compactness, a process for forming a cylindrical rod by cross-wedge rolling (CWR), a CWR process for producing balls that have a diameter which is by 35% larger than that of the billet, quenching of the produced balls. Tools for the above manufacturing operations are designed, and numerical simulations are performed to verify whether the assumptions of the proposed technique are correct. A flat-wedge reversing mill is designed and constructed that enables performing the two abovementioned rolling operations without idle running, which makes the design innovative on a global scale. The implementation of the proposed method would enable producing balls for grinding media used in ball mills. [ABSTRACT FROM AUTHOR]

Tungsten’s unique properties and the excellent cutting and wear resistance properties of its carbides have made it a strategic commodity of high importance globally. Cemented carbides, used for the production of tools and components for metal cutting, rock drilling and wear resistance applications, are highly employed in the manufacturing, petrochemical, construction, gas drilling and mining sectors. These materials, with a typical tungsten content of about 40–95 wt%, become available for recycling and re-use when scrapped. Cemented carbide recycling methods are classified into three categories: (1) direct, (2) indirect and (3) semi-direct. The direct methods have advantages of high recoveries, good quality powders’ production and good grain size control. These methods, however, suffer from incomplete separation of metal carbides from the binding material, require specialized costly equipment and are energy intensive. Indirect methods have the advantage of producing ‘virgin Ammonium para tungstate (APT)’, the most important precursor for tungsten intermediate products such as tungsten trioxide, tungsten blue oxide, tungstic acid and ammonium metatungstate. These methods, however, have a shortcoming of long reaction times and use several conversion steps. The semi-direct methods have the advantage of being low on energy requirement and environmental impact. However, these methods have a disadvantage of slow process kinetics. Statistics show that tungsten-based scrap will become an increasingly important source of raw material for the worldwide tungsten industry. Thus the future prospects of recycling will require optimization of current recycling methods, as well as the possible development of new ones with special emphasis on conversion and energy costs, purity of the scrap metal, recovery of all valuable constituents, as well as diminished environmental impact. In this paper, a review of current research efforts and various methods of scrap recovery, future prospects and sustainability of the tungsten industry, are presented. [ABSTRACT FROM AUTHOR]

Molten salt electrolysis was utilized for the separation of cobalt and tungsten from cemented carbide scrap in the NaCl–KCl melt at 1023 K (750 °C). The WC-15 Co sacrificial anode was dissolved to cobalt and tungsten ions and consequently discharged on the cathode to deposit cobalt and tungsten during electrolysis. The carbon remained at the anode with a porous structure. The oxidation potential of the cobalt and the tungsten carbide in the cemented carbide were analyzed through the electrochemical method. The effects of anode potential, current and duration on the dissolution were investigated. The anodic dissolution processes under different conditions were characterized through SEM and EDX. Subsequently to the two-step electrolysis, the cobalt powders of 100 nm in diameter, the tungsten powders of below 200 nm in diameter and a porous structure of carbon were obtained. [ABSTRACT FROM AUTHOR]

This papers details a simple, sustainable approach for the recovery and concentrating of indium from waste scrap LCD panels. After manual dismantling, the glass fraction of the panel was pulverized through a mechanical treatment, Indium from crushed glass was then mobilized in an acidic solution such as HCl:HNO 3 lixiviant followed by an ultrasonic wave. Indium was successfully adsorbed by three macro porous polystyrene-divinylbenzene resins (Lewatit TP 208, Lewatit TP 260 and Amberlite IRA 743) and the influence of pH, weight of resin, contact time, temperature and type of resin on the efficiency of sorption process were investigated and the optimum condition was found. Theoretical calculations, indicated the In(III) phase formed through the leaching process was InCl 3 (aq). The adsorbed In(III) onto the resins was effectively desorbed in acidic medium to prepare concentrated indium solution. For the kinetic study, the adsorption onto Lewatit TP 208, Lewatit TP 260 and Amberlite IRA 743 could be fitted to pseudo second-order. [ABSTRACT FROM AUTHOR]

Nickel (Ni) and copper (Cu) are the most prevalent metals found in the Greater Sudbury Region ecosystems. The main objectives of this study are to (1) assess silver maple(Acer saccharinum) tolerance to different doses of Ni and (2) determine the translocation pattern of metals inA. sacharinum. This study revealed thatA. sacharinumis highly tolerant to high doses of NI (1600 and 9200 mg/kg). Growth chamber screening trials revealed that Ni is stored in roots and does not translocate to other plant parts. Analysis of samples fromA. sacharinumgrowing for >30 years in soil contaminated with metals also showed that the levels of iron (Fe), manganese (Mn), Ni, and zinc (Zn) were significantly higher in roots compared with soils and aerial parts. On the other hand, the amount of Cu was higher in soil compared with roots and other plant parts. In fact, the bioaccumulation factors (BFs) were 0.29, 2.00, 3.6, 1.9, and 4.0 for Cu, Fe, Mn, Ni, and Zn, respectively. The translocation from roots to aerial parts showed an insignificant level of movement of Cu, Fe, and Ni. Hence,A. saccharinumis classified as excluder for Fe, Mn, Ni, and Zn, and avoider for Cu. [ABSTRACT FROM AUTHOR]

Printed circuit board is an essential part of almost all electrical and electronic equipment (EEE). As the rapid increase of waste EEE (WEEE), caused by the shorter and shorter life span and the accelerated innovation of information communication technologies, waste printed circuit boards (WPCBs) is being a hot issue due to its characteristics of resource abundant but hazardous. In this research, the concentrated metal scraps, obtained by WPCBs mechanical separating, were directly recycled to superfine copper powders by slurry electrolysis. And the effect of polyvinyl pyrrolidone (PVP), oleic acid and H 2 SO 4 concentration, current density and electrolysis time on the purity and particle size of copper powders were discussed in detail. Results showed that all these factors could intensively impact the obtained copper particle size, which became finer as the increase of current density and coarser with the extension of time. Copper powder purity first increased and then decreased as the increase of PVP, oleic acid and H 2 SO 4 concentration. The purity of copper can reach to 99.3% with a particle size of 7.142 μm under the optimum conditions: 30 g/L CuSO 4 ·5H 2 O, 60 g/L NaCl, 150 g/L H 2 SO 4 , 30 g/L PVP, 6 mL/L oleic acid, 80 mA/cm 2 for 4 h. XRD analysis indicated that copper was the main phase; SEM and TEM analysis showed that the obtained copper powders were dendritic single crystal coated by a layer of PVP and oleic acid. Therefore, slurry electrolysis could be a perspective approach for WPCBs recycling. [ABSTRACT FROM AUTHOR]

In this paper we report synthesis of tungsten nanoparticles of high purity >99.7 wt% from heavy alloy scrap using a novel chemical route of selective precipitation and reduction. The effect of Poly(vinylpyrrolidone) polymer on controlling the particle size is established through FTIR spectra and corroborated with TEM images, wherein the average size decreased form 210 to 45 nm with increasing PVP content from zero to 2 g under different experimental conditions. This process is economical as raw material is a scrap and the efficiency of the reaction is >95%. [ABSTRACT FROM AUTHOR]

This paper reports the study on the dissolution behavior of the alnico scraps generated during the manufacture of alnico permanganate magnets. Composition of the scrap used in the study was: 26.09% Co, 16.36% Ni, 47.02% Fe and 8.04% Al. Electroless leaching of the alnico scraps with sulphuric acid had no significant influence on the extraction of metals and which was due to the low surface area and less activity of the scraps. In order to improve the leaching efficiency, electric current was introduced to the system. Various experimental factors such as time, sulphuric acid concentration and current density were studied to determine the best conditions for the dissolution of the metal values. Effective leaching of scrap was due to the synergistic effect of ferric sulphate and temperature both generated during leaching with the current and sulphuric acid concentration in the system. Based on the leaching efficiency, they could be order as Ni > Fe > Co > Al. Under optimum leaching conditions (sulphuric acid 10% (v/v), current density 400 A/m 2 and equilibrium time 4 h), more than 99% of the metal content was dissolved. Based on the process steps involved, a flow sheet was proposed for the commercial application. [ABSTRACT FROM AUTHOR]

The narrative on global shipments of used electronic devices to Africa is incomplete. It focuses on end-of-life device dumping and on health and environmental hazards for local populations. Utilizing fieldwork and interviews in Accra, Ghana, with e-waste processors, scrap recyclers and exporters, local industries, and the Ghana Customs Excise and Preventive Service officials, as well as analysis of customs trade data, Grant and Oteng-Ababio uncover the development of informal urban mining of valuable metals from used electronics, a practice that calls into question conventional city-mine, consumption-production, and waste-resource spatial oppositions. Urban mining is an important heuristic concept for understanding Accra's place within the global political economy and for creating and implementing policies for improving the livelihoods of informal e-waste workers in Ghana and elsewhere. [ABSTRACT FROM AUTHOR]

Disparities in earnings between Western and Eastern European countries are the reason for a well-established informal sector actively involved in collection and transboundary shipment activities from Austria to Hungary. The preferred objects are reusable items and wastes within the categories bulky waste, WEEE and metals, intended to be sold on flea markets. Despite leading to a loss of recyclable resources for Austrian waste management, these informal activities may contribute to the extension of the lifetime of certain goods when they are reused in Hungary; nevertheless they are discussed rather controversially. The aim of this paper is to provide objective data on the quantities informally collected and transhipped. The unique activities of informal collectors required the development and implementation of a new set of methodologies. The concept of triangulation was used to verify results obtained by field visits, interviews and a traffic counting campaign. Both approaches lead to an estimation of approx. 100,000 t per year of reusable items informally collected in Austria. This means that in addition to the approx. 72 kg/cap/yr formally collected bulky waste, bulky waste wood, household scrap (excluding packaging) and WEEE, up to a further 12 kg/cap/yr might, in the case that informal collection is abandoned, end up as waste or in the second-hand sector. [ABSTRACT FROM AUTHOR]

The reuse and recycling of industrial solid wastes such as scrap metal is supported and encouraged both internationally and domestically, especially when such wastes can be used as substitutes for raw material. However, scrap metal processing facilities, such as mini-mills, have been identified as a source of mercury (Hg) emissions in the United States. This research aims to better define some of the key issues related to the source and nature of mercury in the scrap metal waste stream. Overall, it is difficult to pinpoint the key mercury sources feeding into scrap metal recycling facilities, quantify their associated mercury concentrations, or determine which chemical forms are most significant. Potential sources of mercury in scrap metal include mercury switches from discarded vehicles, electronic-based scrap from household appliances and related industrial systems, and Hg-impacted scrap metal from the oil and gas industry. The form of mercury associated with scrap metal varies and depends on the source type. The specific amount of mercury that can be adsorbed and retained by steel appears to be a function of both metallurgical and environmental factors. In general, the longer the steel is in contact with a fluid or condensate that contains measurable concentrations of elemental mercury, the greater the potential for mercury accumulation in that steel. Most mercury compounds are thermally unstable at elevated temperatures (i.e., above 350 °C). As such, the mercury associated with impacted scrap is expected to be volatilized out of the metal when it is heated during processing (e.g., shredding or torch cutting) or melted in a furnace. This release of fugitive gas (Hg vapor) and particulates, as well as Hg-impacted bag-house dust and control filters, could potentially pose an occupational exposure risk to workers at a scrap metal processing facility. Thus, identifying and characterizing the key sources of Hg-impacted scrap, and understanding the nature and extent of associated releases, represent a practical research need that is essential for improving the environmental management of Hg-impacted scrap and assessing measures to protect workers from potential health and safety hazards that might be posed by mercury and Hg-impacted scrap. [ABSTRACT FROM AUTHOR]