Scrap Materials Research Articles

Direct recycling of anode active material from Li-ion batteries using TiNb2O7 anode

As the demand for large lithium-ion batteries (LIBs) for automotive and other applications rapidly grows, recycling of electrode materials has become essential owing to the large amount of waste material generated by battery manufacturing (e.g., battery scrap) and end-of-life (EOL) batteries. While there have been many studies on recycling of cathode materials, we propose a direct recycling process for anode material using TiNb2O7 (TNO) as the active material, as it offers high capacity and long life. Calcination was introduced to separate the anode active material from the current-collecting foil, and a regeneration method was investigated for TNO anodes from scrap and EOL battery waste. After calcination, the active material can be easily separated from the aluminum current-collecting foil owing to the binder disappearing. The structure of the active material was investigated using X-ray diffraction and scanning electron microscopy. TNO active material recycled from scrap and EOL was found to maintain the structure of virgin material. A cell was fabricated using recycled TNO and cell performance was evaluated. The cell capacity and rate capacity were found to be almost equivalent to those of virgin material. In terms of the carbon footprints of products (CFP), CO2 emissions during the recycling process were compared between recycled material and virgin material, and it was found that CO2 emissions were reduced to 0.7-CO2eq/kg for scrap material and 3.8-CO2eq/kg for EOL waste material, compared with 4.8-CO2eq/kg for virgin material. Thus, the feasibility of low CO2 emissions during TNO anode direct recycling was confirmed in principle. A simple and low CO2 emission recycling loop can thus be constructed by employing a stable TNO active material structure and direct-recycling process with calcination.

A sustainable semiconductor supply chain under regulation

Modern life would not exist without semiconductors as all electronic components used in computers, telecommunications, health care, transportation, and energy systems are equipped with chips. To examine both backward and forward activities in semiconductor industry, this paper formulates the industry as a closed-loop supply chain. It articulates how old semiconductors are processed and recycled to manufacture new silicon and chips, and examines the impact of a commonly applied subsidy scheme on the performance of semiconductor firms which operate in upstream and downstream layers of the industry. Specifically, the proposed semiconductor supply chain involves (i) a return function sensitive to monetary incentives; (ii) a subsidy legislation rewarding end-users for recycling; (iii) upstream industry where silicon is produced using virgin and scrap materials; (iv) downstream industry in which semiconductor manufacturers (such as TSMC, Samsung, Intel) buy silicon and other materials, hire workers, and then produce and sell chips. We characterize Stackelberg equilibrium silicon and semiconductor prices and outputs and calibrate model parameters using actual data to quantify the effects of subsidy and collection channels on silicon and semiconductor firms’ performance. We find that the subsidy scheme neither distorts firms’ strategies nor causes any inefficiency for the semiconductor industry. It stimulates circular economy activities and provides economic and environmental benefits.

Selective removal of iron from sulfuric acid leaching solution of aerospace magnetic material scraps by jarosite process

Aerospace magnetic material scraps are abundant in cobalt and nickel. Sulfuric acid leaching process is an efficient method for extracting them. But it is a non-selective process, a significant amount of iron dissolves in the solution. This study focuses on the selective removal of iron from this solution using the jarosite process. Eh-pH diagram of K-S-Fe-H2O system was established. Based on thermodynamic analysis, H2O2 is used to oxidize Fe2+ into Fe3+, achieving efficient and selective removal of iron from the solution containing cobalt and nickel. The optimal conditions are as follows: temperature 95°C, K2SO4 dosage coefficient 1.5, seed dosage 10 g/L, time 90 min, pH 1.76, and endpoint pH controlled at approximately 3. Under these conditions, the iron removal efficiency is above 99%, while the loss ratios of cobalt and nickel are below 2%. The product is characterized by XRD and SEM-EDS. Results indicate that the product is jarosite ((K,H3O)Fe3(SO4)2(OH)6), exhibiting an ellipsoid structure with the mean particle size in the range of 0.2–5.0 μm. Temperature, pH value and seed dosage significantly affect reaction rate, particle size and crystallinity, and K2SO4 dosage mainly affects reaction rate and the morphology of jarosite. The jarosite crystallization kinetics can be described by the Avrami equation, with an Avrami index (n) of approximately 2.5 and the apparent activation energy of 42.68 kJ/mol.

Methodology for shielding design and evaluation for container scanners.

There has been an increase in the use of high energy photon beam for container scanners in many countries for multi purposes such as detecting high atomic number materials which might be nuclear materials, drugs, high explosive materials and other contrabands etc. High energy photon beams generally 6 and 9 MV can be used for scanning such materials. However, it is important to ensure that radiation level beyond the container scanner installation is within the permissible dose limit specified by the national competent authority for the protection of public and radiation workers. In this paper, challenges in the biological shielding during the installation of high energy X-ray system for scanning vehicles containing suspected materials are discussed. The purpose of the present study is to develop a methodology for shielding design and evaluation for container scanner installations. The basic concept pertaining to shielding evaluation of radiotherapy installations provided in National Council on Radiation Protection and Measurements (NCRP)/International Atomic Energy Agency (IAEA) reports are referred, and appropriately used to calculate optimized shielding thicknesses requirements for container scanner installation. Workload is estimated based on number of containers scanned, machine ON time and dose rate at 1m. The shielding evaluation includes use of beam stopper in the primary beam, scattering by heterogeneous metallic scrap materials or any other suspected materials contained in the vehicle and their impact on the thickness of shielding walls. A model lay out plan to be used for installation of container scanner is developed. A methodology for shielding evaluation for various protective walls and ceiling of this model is also discussed. The study provides basic requirement for designing a structural room for installing 9MV container scanner from radiological safety view point.

Modernization of the stamping process using eddy current and load sensors in the manufacturing of automotive parts

In this research, an experimental study is presented, which extends the usage of eddy current and load sensors in progressive stamping tools to optimize and continuously monitor the stamping process. The purpose of the research was to automatically detect material scrap before it leaves imprints on the part and based on the sensor’s readings, determine the optimal tool bottom position. The scrap thickness that needs to be detected was established in an experiment by visual evaluation of the result. To determine the optimal bottom position, a linear regression method was used, and the results were evaluated by part quality parameter. The research results consist of separate detection steps and the conclusion was made only after the serial type production. Overall results of scrap detection were influenced by the design of the existing tool. The bottom position detection consists of various readings interpretations and multi-step method descriptions. Based on the acquired results of both methods, implementing the in–die sensors was considered successful and applicable to new tools.

Modeling solute drag during austenite–ferrite transformation with ab initio binding energies

The solute drag effect can have a considerable impact on the austenite to ferrite transformation. Most models describing the solute drag effect require knowledge of solute binding energies, which due to lack of accurate data typically are treated as fit parameters. In this study we use density functional theory (DFT) calculations to estimate the effective binding energies of the substitutional alloying elements in an ultra low carbon steel. For the first time these energies are used to calculate the solute drag effect considering site competition for the austenite to ferrite phase transformation. The depletion of elements in solid solution as a result from precipitation is computed and the solute drag contribution of each element is calculated. Comparison of the binding energies with the resulting solute drag effect to literature data shows reasonable agreement. The outlined approach points the way to future alloy development based on interface-controlled integrated computational materials engineering. Another field of application is given by the circular economy driven transition in the steel industry from the BF/BOF- to the EAF-based production route with increased utilization of scrap material introducing new tramp elements.

New methodology for estimating the influence of Cu content of Ferrous Scrap materials in the Total Cost of Operation (TCO) of scrap mix in Electric Arc Furnace steelmaking

Scrap is the main raw material of the electric arc furnace (EAF) route of steelmaking and an important one in the primary route. The decarbonisation commitment acquired by the most relevant steelmaking companies, will only increase the amount of scrap used by both routes, making it a critical component to succeed in the worldwide challenge of reducing CO2 emissions. While being a very relevant material, scrap characterisation is complex due to its heterogeneity, but furthermore, its quality is worsening as its demand increases. This includes the sterile content, such as copper. Higher sterile content scrap comes at a lower price, while scrap with a lower content in undesired elements is most costly. Being able to balance the cost and benefit of purchasing scrap with a higher or lower content of copper with a respective, lower or higher purchase cost would be of interest to optimise the mix and produce the required quality steel at the lowest possible cost. Nowadays, this cost benefit analysis can only be done by performing Total Cost of Operation (TCO) calculations that require a considerable amount of information, including but not limited to the complete chemical composition of scrap, market parameters, production forecast and other relevant data; moreover, involving an arduous optimization process. Based on a parametric study of the TCO calculation, this work proposes a mathematical model to estimate the impact on the TCO of a predefined scrap mix when only modifying the specifics of one given scrap type. The results would facilitate the decision making by comparing the two scenarios as a factor of cost. This mathematical model can be easily programmed and requires only 5 parameters to be run, while providing a low error result.

Electrorefining for copper tramp element removal from molten iron for green steelmaking

Steel recycling is crucial for lowering greenhouse gas emissions and reducing the pressure on natural resources within the manufacturing sector. Yet, the challenge of effectively dealing with impurities like carbon and tramp elements (copper), in scrap materials, persists as a major obstacle that current technologies fail to fully overcome. This study introduces an innovative oxysulfide electrolyte for electrorefining that significantly enhances steel recycling by effectively removing carbon and copper impurities from molten iron. This method not only achieves simultaneous extraction of these elements but also generates liquid iron and sulfur as by-products. By applying an electromotive force, this approach propels non-spontaneous electrochemical reactions, achieving refining efficiencies surpassing traditional methods. Results indicate a substantial reduction in carbon levels and copper to as low as 790 ppmw from 0.43 wt% Cu from molten iron can be achieved. The electrorefining process using this electrolyte offers a promising solution for improving scrap recycling in secondary steel production, highlighting its potential for reducing emissions and overcoming current technological limitations.

Optimizing Auto Manufacturing: A Holistic Approach Integrating Overall Equipment Effectiveness for Enhanced Efficiency and Sustainability

In the face of pandemic-induced emergencies and unpredictable natural disasters, industries are compelled to implement rescue plans to mitigate unexpected risks. In this context, Overall Equipment Effectiveness (OEE) is considered as a key metric, followed by sustainability efforts to manage unforeseen risks, encompassing social, environmental, and economic aspects. OEE is considered as a lean tool to determine the efficiency of equipment or processes on par with the world class OEE standard, i.e., 85%. Performance, Availability and Quality as three main drivers of OEE. This research study explores the implementation of OEE in conjunction with sustainability principles in an auto sector manufacturing firm, aiming to enhance operational efficiency and sustainability practices. The research involves a 12-week initial session from April to June 2022, followed by an analysis of July to September 2022, resulting in an impressive OEE value of 48%. Notable improvements in Availability (89.75%), Performance (72.68%), and Quality (73.82%) contribute significantly. The analysis reveals enhancements in scrap rework (17%), training (16%), maintenance (13%), material availability (12%), and production capability (11%). Achievements include improvements in green profile (25%), health and safety (20%), and energy efficiency (25%), along with reductions in carbon dioxide emissions (21%), waste management (17%), and scrap (15%). This research underscores the commitment of the case study industry to sustainable development and economic growth, showcasing significant enhancements in product quality and efficiency. The integration of sustainability principles into OEE initiatives is pivotal for modern industrial optimization. The study results highlight the profound significance of this synergistic relationship, particularly within the blending section, driving substantial positive outcomes in manufacturing processes and operational excellence. The implementation of sustainability efforts not only mitigates risks and fosters growth for automotive manufacturers but also yields environmental benefits. Based on findings of this study, a roadmap for automotive manufacturers is devised to achieve robust OEE while concurrently reaping economic and environmental rewards by employing sustainability principles.

Deflection and Elastic Modulus Assessment of Subgrade in Flexible Pavement mixed with Waste Tire Scrap Material

This study aims to assess the deflection and elastic modulus (Es) of subgrade in flexible pavements, focusing on a comparative analysis between pavements with clayey soil subgrade and subgrade modified with tire scrap. The research utilized Falling Weight Deflectometer (FWD) for measuring subgrade deflection, essential in evaluating pavement performance. The FWD applied a dynamic load to the pavement, with deflection measurements processed using the KGP-BACK software to calculate the Es of the pavement subgrade. This approach included assessing the Lower Layer Index (LLI) and Es of the subgrade. Findings revealed a notable reduction of 37.5% in deflection and 2.68 times increase in Es for the tire scrap modified subgrade pavement compared to the standard clayey soil subgrade pavement. These results demonstrate significant enhancements in pavement structure, underlining the potential of recycled materials in sustainable civil engineering practices.

Development of a self-reinforced starch-derived film with biocompatibility and mechanical properties

The scraps produced while processing packaging materials will cause a waste of resources. In this study, starch-based self-reinforced film (SSRF) using thermoplastic starch (TPS, 45 wt%) and polypropylene (PP, 53 wt%) was developed. The effect of extrusion times (1–4 times) on the film structure and performance was explored. The results show as the number of extrusions increases, the color of SSRF deepens from gray-white to brown, and the crystallinity increases. The mechanical properties of the four types of SSRF first increase and then decrease. The 2-SSRF has the best performance, with tensile strength of 13.23 MPa, elongation at break of 61.35%, Young's modulus of 1128.99 MPa, and flexural strength of 33.19 MPa. Proper extrusion improves the compatibility of TPS and PP. However, repeated extrusion will cause PP degradation and TPS carbonization, reducing interfacial interaction. This study developed new starch-based self-reinforced film and provided theoretical guidance for reusing packaging material scraps.

The Effectiveness of HEVs Phase-Out by 2035 in Favor of BEVs with Respect to the Production of CO2 Emissions: The Italian Case

The EU has planned the phase-out of new vehicles based on internal combustion engines in favor of high-efficiency battery electric vehicles (BEV) by 2035 (Fit for 55 package). However, many doubts remain about the effectiveness of this choice for each country of the Union in terms of CO2 emissions reduction, as each State is characterized by a different carbon intensity related to the production of electricity needed to manufacture and recharge vehicles. This study seeks to explore the Italian case. To this aim, carbon intensities related to electricity production were calculated considering both the Italian electricity mix production in 2022 and those envisaged in 2035, considering two energy scenarios based on different introductions of renewable energy sources (RES). Afterward, the values obtained were adopted for determining the CO2 emissions related to the whole production process of battery systems in Italy (emissions from mining and refining, scrap materials, and final assembly included) by comparing some of the most up-to-date Life-Cycle Assessment (LCA) analyses related to the manufacturing cycle of the batteries. Finally, the results were adopted to calculate the starting carbon debit for A, B, C, and M car segments for Mild Hybrid, Full Hybrid, and Full Electric powertrains. At the same time, statistical road fuel/electricity consumption data were collected and overall CO2 emissions were calculated for the same vehicles adopting a dynamic approach and plotted for a defined distance, so as to determine break-even points with respect to the cumulative (i.e., from battery and road) carbon emissions. The results showed that advantages related to electric vehicles are significant only if a low carbon intensity related to electricity production is reached by means of a very high introduction of RES, thus keeping the door open for innovative hybrid powertrain technologies, if fed with low carbon fuels.

Environmental impact assessment of steel reinforcing bar manufacturing process from scrap materials using life cycle assessment method: a case study on the Ethiopian metal industries

A clear understanding of the major environmental impacts of steelmaking from scraps, as well as potential solutions involving a circular economy paradigm, is essential. This study is conducted to pave the way for using life cycle assessment (LCA) to have sustainable development and effective resource management by evaluating the environmental impacts of the steel rebar manufacturing process using secondary resources. It is a cradle-to-gate LCA that includes scrap collection and sorting, transportation, melting, continuous casting, billet reheating, and reinforcing bar rolling. Inventory data were acquired as primary data from the factory and secondary data from ecoinvent v3.8, 2021 version integrated with SimaPro 9.4.0.2 faculty version. All of the analyses in this LCA were conducted using the Recipe 2016 Midpoint (H)V1.00 and Endpoint (I)V1.00 impact assessment techniques taking one-ton reinforcing bar production as reference flow. This LCA study shows that using renewable energy and bulk transport systems has a significant advantage in reducing the environmental impact created during steel production processes. Because of this, the global warming potential created during the rebar manufacturing process is 467 kgCO2 eq as taken from the environmental impact calculation report. By charging hot billet from the continuous casting machine (CCM) to the rolling mill and using an efficient transportation system, the environmental impact of GWP can be reduced by 50%.

Modeling laser processing of materials

For a long time, the complexity of the phenomena occurring during the laser exposure to the material made possible the mainly experimental selection of processing modes. The analysis of the thermal processes taking place at the same time and the programs being used require in-depth knowledge of physical phenomena, as well as broad capabilities of computing equipment, so they have become inaccessible to many researchers. Goal. The purpose of the study is to model the interaction of laser radiation with substance on the example of acrylic glass using the COMSOL Multiphysics 5.5 software package. Methodology. The scrap material for research was acrylic extrusion glass according to GOST 17622-72 and GOST 10667-99. Successful laser treatment requires maximum absorption of radiation, so a CO2 laser with a wavelength of 10.6 microns was chosen for the research. Other laser processing parameters (power 10 W, focus point diameter 1 mm, pro-menu movement speed 40 mm/s) are typical for the StoLaser Standard 4030 Mini installation. Results. The main task was modelling of the interaction of laser radiation with substance on the example of acrylic glass using the COMSOL Multiphysics 5.5 software package. The paper investigates the peculiarities and nature of the interaction of laser radiation with acrylic glass using the finite element method, as well as with the help of the COMSOL software complex, which works according to this method. A program for modelling the interaction of a laser beam with a material, in this case non-metallic, was created experimentally. A graphical distribution of heat on the surface and an isotherm of the depth of heat distribution inside the material were obtained. Scientific novelty. In this paper, a model of the passage of laser radiation through a block of dielectric material was created using the COMSOL Multiphysics package. The possibility of modeling laser processing of materials by the finite element method was proven. Practicality. The developed model can be used when choosing the modes of laser processing of various materials.

Direct recycling of lithium-ion battery production scrap – Solvent-based recovery and reuse of anode and cathode coating materials

The rapid growth in the use of lithium-ion batteries is leading to an increase in the number of battery cell factories around the world associated with significant production scrap rates. Direct recycling of this scrap material has both environmental and economic benefits, such as reducing the carbon footprint of cell manufacturing, as well as reducing production costs and raw material requirements. In this work, a solvent-based direct recycling route for anode and cathode coating materials is presented that allows direct reuse of the recovered coating materials. A high yield of recovery is achieved by mechanical stress in a suitable solvent (96 % for anodes, 85 % for cathodes). The resulting suspension is used for electrode production to study the influence of direct recycled material on the resulting electrode and cell performance. It can be seen that the electrodes and cells with up to 10 % recyclate content have similar high performance in terms of electrical conductivities, initial discharge capacity (approx. 165 mAh g−1 for graphite/NMC622 coin cells) and C-rate stability. Overall, the work demonstrates that direct solvent-based recycling is an efficient method for recycling electrode scrap without compromising the performance of the cells produced when fresh material is added to the recycled suspension.

Negative-carbon recycling of copper from waste as secondary resources using deep eutectic solvents

Copper plays a crucial role in the low-carbon transformation of global communities with prevalent use of electric vehicles. This study proposed an environmentally friendly approach that utilizes a deep eutectic solvent (DES), choline chloride-ethylene glycol (ChCl-EG), as green solvent for the selective extraction of copper from scrap materials. With hydrogen peroxide as an oxidizing agent, the copper species from the printed circuit boards (PCBs) scraps were efficiently leached by the DES through oxidation-complexation reactions (conditions: 25 min, 20 °C, and 5 wt% H2O2). Molecular dynamics and density functional theory were performed to simulate the intricate cascade of interactions between copper species and hydrogen bond donors/acceptors of DES, providing insights into the mechanistic processes involved. Copper was selectively recovered from the DES leachate containing impurities (e.g., Pb2+, Sn2+, and Al3+) through electrodeposition via a diffusion-controlled reaction under a constant potential mode. A comprehensive life cycle assessment of the process demonstrated that the utilisation of DES in the extraction of copper from waste PCBs could result in significant reduction in carbon dioxide emissions (−93.6 kg CO2 eq of 1000 kg waste PCBs), thus mitigating the carbon footprint of global copper use through the proposed solvometallurgical recycling process of secondary resources.

DOES - A multimodal dataset for supervised and unsupervised analysis of steel scrap

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.

Process Development of Screen-Printed Magnetic Sheets for Electric Machines via Statistical Design of Experiments

Electrical machines play a major role in achieving a more sustainable economy by driving the further electrification of industry and transportation. To enhance the electric motor productivity during production and the efficiency during operation, it is essential to maximize the material yield rate during the production of stator and rotor sheet stacks and reduce iron losses during operation. Screen-printing technology can help to achieve these goals by producing thin magnetic sheet laminations in near-net-shape geometry, resulting in minimum material waste during production. Moreover, reducing the sheet thickness decreases the eddy current losses and avoids mechanical stress during manufacturing, leading to improved motor efficiency. Additionally, screen printing facilitates the production of multi-material components and variable alloy compositions. This study aims to identify the relevant factors and printing parameters so that screen-printed magnetic sheets can achieve product specifications. A method involving the statistical design of experiments is performed in several iterations to investigate the target parameters of the print cycle time, green part weight, shape integrity and layer thickness, and to analyze the main interdependencies. The results of this study provide valuable insights into optimizing the screen-printing process for soft magnetic sheets, enabling the production of efficient electric motors while reducing material scrap.

Direct Recycling of Hot‐Deformed Nd–Fe–B Magnet Scrap by Field‐Assisted Sintering Technology

Recycling of Nd–Fe–B magnets is an ongoing challenge regarding circular economy. State‐of‐the‐art magnet production methods, such as hot deformation, have limitations with respect to direct recycling of magnet scrap particles that differ from pristine melt‐spun Nd–Fe–B powder. Recent work has shown that a combination of presintering by field‐assisted sintering technology/spark plasma sintering (FAST/SPS) and hot deformation by flash spark plasma sintering (flash SPS) has the potential to directly produce Nd–Fe–B magnets from 100% scrap material. Both processes have the capability to adjust and monitor process parameters closely, resulting in recycled magnets with properties similar to commercial magnets but made directly from crushed and recycled Nd–Fe–B powder that partially or completely replaces pristine melt‐spun Nd–Fe–B powder. Herein, a systematic study is done inserting recycled magnet particles into a flash SPS deformed magnet, considering the effects of different weight percentages of scrap material of varied particle size fractions. In some cases, coercivity HcJ of >1400 kAm−1 and remanence Br of 1.1 T can be achieved with 20 wt% scrap material. The relationship between particle size fraction, oxygen uptake, and percentage of recyclate in a final magnet are all explored and discussed with respect to magnets made from pristine material.

Recycling fibre-reinforced composite parts

Recycling fibre-reinforced composite parts Uncured carbon fibre recycling by Bulk Moulding Compound (BMC). Another route to valorise the fresh carbon prepreg scrap from aeronautical field has been stablished by Gaiker in MC4. In this case the scrap is used to develop bulk moulding compound (BMC), an intermediate product relying on short fibre, for production of new composite for transport applications. This new approach permits valorise a wide range of fresh prepreg scrap without any dimensional restrictions. This scrap is ground to reduce the fibre length and manufacture a BMC material mixing with new virgin resin formulation. An appropriate virgin resin formulation should be defined based on properties of scrap to ensure the compatibility between scrap and virgin material. The BMC produced is transformed to final composite part by a moulding process where temperature, pressure and time should be stablished to ensure the polymerization of material as well as correct geometry qualities and tolerances. Regarding the properties of this new composite, the initial studies reveal that the mechanical performance of the composite produced with new BMC is equivalent to commercial BMC based on virgin raw materials, with more than 250 MPa of flexural strength and more than 80 MPa of tensile strength.