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In North America, the infrastructure for sorting aluminum from automotive scrap is fairly extensive with roughly 6000 scrap collection and dismantling yards, 200 scrap shredders, and ten sink-float plants currently in operation. Almost half of the aluminum contained in an automobile is removed directly in the dismantling yard and recycled. The othe...
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... Literature from the last two decades that focused on the need to increase scrap-based production or improve scrap usage share a common theme: the need to address the uncertainties in scrap compositions as input materials, whether this be by the use of advanced separation technologies for end-of-life products (Lu et al., 2022), better control of scrap quality (Mehlhart et al., 2016), expanding of the infrastructure for collection and sorting scrap (Javaid and Essadiqi, 2003;Michaelis and Jackson, 2000), use of specialized commercial standards (Bracquené and Duflou, 2019), or deployment of Best Available Techniques (BAT) (Remus et al., 2013). The issue has long been recognized yet persisted. ...
... Many publications and research activities on scrap classification focus on shredded scrap, non-ferrous materials and techniques such as LIBS (laser induced breakdown spectroscopy) or multi-spectral image analysis, e.g. [17][18][19][20][21][22][23] . Publications focusing on ferrous scrap classification in steel plant settings do not provide reference to the dataset used or discuss classification techniques without providing classification results, e.g. ...
DOES - Dataset of European scrap classes. Today, scrap is already an important raw material for industry. Due to the transformation to green steel, the secondary raw material scrap will become increasingly important in the coming years. With DOES a free dataset is presented, which represents common non-alloyed European scrap classes. Two important points were considered in this dataset. First, scrap oxidizes under normal external conditions and the visual appearance changes, which plays an important role in visual inspections. Therefore, DOES includes scrap images of different degrees of corrosion attack. Second, images of scrap metal (mostly scrap piles) usually have no intrinsic order. For this reason, a technique to extract many overlapping rectangles from raw images was used, which can be used to train deep learning algorithms without any disadvantage. This dataset is very suitable to develop industrial applications or to research classification algorithms. The dataset was validated by experts and through machine learning models.
... MAIN MATERIAL The aluminum recycling process can be divided into aluminum scrap sorting, aluminum purification and particle size separation [13,22,[29][30][31]. Density separation is one of the first procedures in extracting aluminum from the scrap mix and reducing its mass and dimensions to be suitable for the use in smelting furnaces [32][33][34]. ...
... The other half is passed into the shredder. As a result of three separation techniques: magnetic, air and Eddycurrent separation, the composition of the scrap increases from 2.5 to 5% to nearly 70% Al [286]. Maximizing Al recycling is of importance for energy savings since the secondary metal produced from recycled metal requires only about 2.8 kWh/kg of metal produced, while the primary Al production requires about 45 kWh/kg of metal produced [287,288]. ...
Rare-earth metals create unique opportunities in improving properties of aluminum alloys. For over a century, there have been attempts to explore cerium for aluminum alloying, emphasizing advantages it exhibits among rare earths. This review covers laboratory and industrial efforts of applying cerium for a purpose of developing aluminum alloys with superior properties. The binary Al–Ce, ternary Al–Ce–X and higher-order phase systems are reviewed with a focus on the aluminum-rich sections. The role of cerium in forming stable, high-melting-point compounds, improving strength and thermal stability is analyzed along with its function as a grain refiner in the aluminum melt, the eutectic modifier, as de-gasifying and de-slagging agent through its reaction with gas and liquid impurities. In addition to conventional alloys with cerium as a minor and major ingredient also amorphous alloys along with aluminum matrix nanocomposites, exploring cerium oxide as reinforcement, are assessed. The role of cerium in bulk alloying is expanded to surface engineering solutions enhancing aluminum wear and corrosion resistance. Efforts of cerium recovery from parts after end of service life and alloy design for a recycling friendly world are discussed to minimize losses and prevent contamination of material supply chain in modern manufacturing.
... The new researches propose some new methods for the recycling of aluminum alloys used Laser Induced Breakdown Spectroscopy (LIBS) method which is the only method to separate both cast and wrought aluminum into their individual alloys. The major limitation for the LIBS is that the surface of the aluminum scrap must be free of paints, lubricants or adhesives, since the pulse laser can only penetrate to a depth of 30 Å or less on the surface of the aluminum [7], [8]. The other researches propose pressing and hot extrusion aluminum alloy by cold and hot pressing followed by hot extrusion but this method is expensive [9]. ...
Annual anthropogenic greenhouse gas emissions must be cut by 40-70% by 2050 to limit global warming this century to 2o C above the pre-industrial temperature and avoid the worst consequences of climate change. This cut in global emissions is likely infeasible without U.S. decarbonization efforts equaling the global target. The transport and industry sectors account for 57% of U.S. GHG emissions. These two sectors must decarbonize and match the target if the U.S. is to achieve the necessary cut in emissions. Emissions from U.S. transport and industry are coupled with advanced transport technologies (e.g., battery electric vehicles (BEVs) with Li-ion batteries) typically requiring emissions-intensive manufacturing. Previous studies have largely ignored the transport-industry emissions nexus. Instead, this thesis presents a parametric fleet-scale production-use-disposal model that combines life cycle assessment with macro-level consumption parameters to calculate consumption based cumulative emissions and global temperature changes attributable to U.S. light duty vehicles (LDVs). Future pathways account for emerging powertrain technologies, electricity decarbonization, transport demand, recycling rates, and vehicle lifespans. Only 3% of the 1,512 modeled pathways meet the emissions target. Without aggressive actions, U.S. LDVs will likely exceed the cumulative emissions budget by 2039. Cumulative emissions are most sensitive to transport demand and the speed of fleet electrification and electricity decarbonization. Increasing production of BEVs to 100% of sales by 2040 (at the latest) is necessary, and early retirement of internal combustion engine vehicles is beneficial. Rapid electricity decarbonization minimizes emissions from BEV use and increasingly energy-intensive vehicle production. Deploying high fuel economy vehicles can increase emissions from the production of BEV batteries and lightweight materials. Increased recycling has only a small effect on these emissions because over the time period there are few batteries and lightweight materials available for recycling. A quarter of U.S. industry emissions are from the steel and aluminum sectors. Previous studies have shown that there are limited opportunities for further energy efficiency improvements in these upstream industries; however, increased material efficiency might prove fruitful, where services are delivered using less emissions-intensive materials produced from natural resources. Detailed material flow analyses (MFAs) are needed to identify the opportunities for material efficiency and to model the supply chain emissions. MFA construction is time consuming and fraught with missing and contradictory data. This thesis presents an easily updatable nonlinear least squares data reconciliation framework for MFA that is then applied to the annual U.S. steel flow. The MFA reveals key opportunities for U.S. steel material efficiency: increased manufacturing process yields and domestic recycling of landfilled and exported scrap. To understand the barriers to increased recycling, an optimal reverse supply chain model is derived using linear programming (LP). It shows that U.S. domestic steel and aluminum recycling is already constrained by compositional mismatches between the scrap streams and industry demand. The LP model is coupled with a dynamic material flow analysis to show that the increasing volumes of high-quality wrought aluminum being used in U.S. vehicles are likely to be downcycled or landfilled at vehicle end-of-life. The LP model is revised to show the potential for using emerging scrap separation and refining technologies to increase closed-loop recycling rates towards 90%. The technical assessments presented here highlight the scope for change. In future work, socioeconomic analyses could be coupled with these models to further assess the viability of the material efficiency strategies highlighted throughout.
In the framework of the industry of secondary aluminum, the chemical neutralization of highly reactive materials that come from the pre-treatment screening processes of scraps (beverage cans and domestic appliances) was investigated through experiments in aqueous alkaline solutions. Metallic aluminum-rich by-products are classified, according to EU law, as dangerous waste, as they can potentially develop flammable gases capable of forming explosive mixtures with air. In this way they cannot be disposed of in landfills for non-hazardous wastes if chemical neutralization is not planned and performed beforehand. In this way, these experiments were mainly aimed at unraveling the oxidation rate and at quantifying the production of hydrogen-rich gases from the reactions of the metallic aluminum-rich by-products in a water-rich alkaline (liquid or vapor) environment. Reactions were carried out in a stainless-steel batch mini-reactor with metering and sampling valves, with the resulting gases analyzed by gas-chromatography (GC). The experimental setup was planned to avoid the following issues: (i) the corrosion of the reactor by the alkaline solution and (ii) the permeability of the system to hydrogen (i.e., possible leaks of H2), related to the fast kinetics and short duration of the reactions (which may hinder a pileup effect) between the solid by-products and the liquid. The procedure was defined by a controlled interaction process between metals and liquid, using NaOH to increase reaction rates. The experimental runs performed in the mini-reactor proved to be effective for eliminating the reactive metallic aluminum, reaching a maximum hydrogen production of 96% of the total gases produced in the experiments. The relations between gas generation (up to 55 bar of H2 in the experiments, which lasted for four days) and each specific parameter variation are discussed. All the obtained results can be transferred and applied to (i) the possible industrialization of the method for the chemical neutralization of these dangerous by-products, increasing sustainability and workplace safety, (ii) the use of the resulting hydrogen as a source of energy for the furnaces of the secondary aluminum industry itself, and (iii) new technological materials (e.g., "foamed geopolymers"), by using hydrogen as a foaming agent, coupled with aluminosilicate materials, during geopolymeric reactions.
Scrap yards have long been responsible for identifying and sorting specific alloys from large quantities of mixed metals by means of visual and cognitive recognition with the aid of a few standard tools (a magnet, file, acids, and/or grinding wheel). Performing visual inspection successfully requires extensive knowledge obtained through years of experience physically handling material. This level of expertise cannot reasonably be expected of all those in the operations process but, the right instrumentation in capable, well-trained hands could work to bridge the difference between an expert and a novice. Handheld analyzers (HHs) that utilize X-ray fluorescence (XRF) and laser induced breakdown spectroscopy (LIBS) technology offer a level of technological assistance that could improve identification during the inspection process. Although the technology harnessed by these instruments is not new, the accessibility of it is- which has allowed the functionality, performance, and purpose of these HHs to expand. Subsequently, the attractiveness of these instruments goes beyond being able to obtain results similar to laboratory analysis. HHs are in-field ready, and the ergonomics, safety settings, read times, data sharing and accessibility are continually improving. Additionally, the costs of HHs are shrinking; this coupled with the opportunity to improve profit and avoid loss through reducing incorrect identification produces the more immediate return on investment (ROI) that yards require. Currently, we have a good indication of how HHs perform on material that has clean, smooth, uncoated surfaces but, what we aim to find is their response when used on “unprepared materials,” like those coming out of stock that are old, used, weathered, and/or warped. For these instruments to be deemed useful for inbound inspection/ identification purposes, it is crucial to understand and evaluate their limitations on scrap that is not altered and thus, true to a yard setting. Our results indicate that in their current state, HHs can inform and verify content for a significant range of materials, but there are still metal types and conditions that exist that lead to unreliable reporting of compositional percentages.
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.
In general, aluminum alloys at industrial end-of-life are considerably recycled into aluminum alloys, but they are mostly recycled as alloys for casting because their acceptable concentration limits are not strictly designated and not comparable with those of wrought alloys. This means that recycling from end-of-life wrought alloys to cast alloys has been practiced instead of closed-loop recycling from end-of-life wrought alloys to wrought alloys. The energy required for producing aluminum from recycled aluminum is only 5 % of the energy required for producing aluminum from bauxite. In addition, refining material into wrought aluminum alloys requires many primary aluminum ingots. In terms of saving energy and resources, it would be better if we could conduct closed-loop recycling from end-of-life wrought alloys to wrought alloys. In this study, a combination of X-ray transmission and eddy-current testing is examined with the aim of sorting wrought aluminum alloys. The seven types of wrought aluminum alloys were only sorted into three groups by using X-ray transmission testing and eddy-current testing, while they were sorted into six groups by using a combination of X-ray transmission and eddy-current testing.