Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences最新文献

In the context of the European Critical Raw Materials Act, this work attempts to demonstrate the potential of residual material flows from non-ferrous metallurgy and their possible contribution to the supply security of metals by locally available new secondary resources, assuming technically and economically viable processing. Based on the aluminium, zinc, copper and lead industries, the resulting waste streams are discussed and, in particular, the complex process consisting of physical, chemical and metallurgical steps is described. Their diversity, be it slags, dusts or even sludges, has a wide variety of morphologies and compositions due to the process of generation. In the past, many concepts for reprocessing were investigated, but the goal was usually only the recovery of one target element or to avoid landfilling by using it, for example, as a building material, whereby the metals contained are completely lost. If the target is the extraction of valuables, the required interdisciplinary process development must be based on an in-depth characterization to understand the behaviour of metals and trace elements in possible extraction steps and also to develop suitable strategies for influencing the behaviour of target elements with the aim of extraction. This starts with an in-depth comprehension of the formation process, which is the subject of this article and has a direct influence on the composition and morphology of the materials, thus forming the basis for understanding the behaviour in potential recycling processes. Furthermore, typical compositions of the residual material streams, sources and, if available, quantities are shown and, in summary, an attempt is made to evaluate the materials in a SWOT analysis and to address the challenges in developing extraction steps for processing. While mine tailings are mostly found outside of Europe, the potential of the residual materials from metallurgy is local due to the processing of the concentrates in Europe. This leads to several potential advantages in a possible reprocessing, such as no or shorter transport routes, which is linked to lower quantity of emissions, defined volume and known composition, no geopolitical risk, conservation of primary resources, and increasing Europe's sustainability through a more comprehensive use of the raw materials.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

The ever-increasing market demand and the rapid uptake of the technologies of electronics create an unavoidable generation of high-volume electronic waste (e-waste). E-waste is embedded with valuable metals, alloys, precious metals and rare earth elements. A substantial portion of e-waste ends up in landfills and is incinerated due to its complex multi-material structure, creating loss of resources and often leading to environmental contamination from the release of landfill leachates and combustion gases. Conversely, due to the ongoing demand for valuable metals, global industrial and manufacturing supply chains are experiencing enormous pressure. To address this issue, researchers have put multifaceted efforts into developing viable technologies and emphasized right-scaling for e-waste reclamation. Several conventional and emerging recycling technologies have been recognized to be efficient in recovering metal alloys, precious and rare earth metals from e-waste. The recovery of valuable metals from e-waste will create an alternative source of value-added raw materials, which could become part of supply chains for manufacturing. This review discusses the urgency of metal recycling from e-waste for sustainability and economic benefit, up-to-date recycling technologies with an emphasis on their potential role in creating a circular economy in e-waste management.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

Decarbonizing the global steel industry hinges on three key limited resources: geological carbon storage, zero-emission electricity and end-of-life scrap. Existing system analysis calls for an accelerated expansion of the supply of these resources to meet the assumed ever-increasing steel demand. In this study, we propose a different view on how to decarbonize the global steel industry, based on the principle that resource supply can only expand in line with historical trends and actual construction plans. Our analysis shows that global steel production cannot grow any further within a Paris-compatible carbon budget, resulting in a shortfall of approximately 30% against 2050 demand. This trajectory involves the phasing out of blast furnaces, along with strong growth in scrap recycling and hydrogen-based production. These findings highlight critical yet often overlooked challenges: (i) reducing excess demand while providing essential services, (ii) producing high-grade steel through upcycling scrap, and (iii) ensuring an equitable distribution of limited production across the globe. These perspectives contrast with those of the current agenda, which largely emphasizes the need to invest in new production technologies. Grounded in a physical basis, this analysis offers a complementary perspective for a more balanced debate in policymaking and industrial strategy. This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

A transition to a more sustainable human-nature system is inextricably linked to raw materials production, if economic growth is to be maintained or increased by the emergence of new, energy- and metal-hungry technology innovation clusters. The dependence on mined raw materials is a wicked problem for societies vulnerable to negative ecological impacts and for global power bases wanting to secure access to an increasing array of feedstocks. We interrogate the issue of what constitutes a sustainable metal from a triple perspective: (i) the characteristics of ore deposits and the primary extractive operations that supply critical raw materials; (ii) the impediments for complex and interacting supply chains to maintain critical (and other) metals in use; and (iii) the lack of transparency in supply chains that makes it challenging for customers to avoid resources that have been produced by unsustainable and poor practices. We examine existing and emerging structures for resource management to explain the limits to the circular economy and what constitutes a meaningful systemic structure for primary production by responsible mining. We call for the inclusion of a standardized statement of the 'natural capital' embodied in R&D for technological materials as a means to create transparency about what constitutes a sustainable metal.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

The global steel sector is undergoing a transition from being a major CO₂ emitter to a more sustainable circular material service provider, moving towards (near) net zero CO₂ through combined strategies of reuse, remanufacturing, recycling and changes to primary steelmaking. This paper considers the transition using the UK as an example, based on the current sector state and future plans/opportunities. Some key enablers/barriers have been identified, and case studies are presented on the current state of knowledge and technology developments. For example, increasing reuse/remanufacturing requires data on the component's remaining life at the end-of-product life; in this work use of in-service monitoring for steel-intensive applications in the transport sector is discussed identifying sensor types/locations for fatigue loading assessment for different use conditions to feed into material/product passports for reuse/remanufacturing decisions. Increased recycling of obsolete scrap has implications for composition control with increases in residual elements, such as Cu, Sn, Cr and Ni inevitable. Current and future approaches to recycling and scrap sorting are discussed along with case studies for how residual elements affect microstructural development during steel processing, including effects on recrystallization, phase transformation and fine-scale precipitation, which potentially could be exploited to give increases in product strength. This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

Energy infrastructure requires metals, and metals production requires energy. A transparent, physical model of the metals-energy system is presented to explore under what conditions this dependence constrains or accelerates the transition to a net-zero economy. While the mineral (as high as 340 Mt yr^-1 iron ore, 210 Mt yr^-1 limestone, 250 Mt yr^-1 bauxite and 5.5 Gt yr^-1 copper ore in the 2040-2050 decade, assuming no improvements) and total energy (up to 22 EJ yr^-1) requirements for building low-carbon energy infrastructure are significant, it compares favourably with the current extraction and energy use supporting the fossil fuel system (15 Gt yr^-1 fossil minerals and ~38 EJ yr^-1). There are levers to significantly reduce material use and associated impacts over time. The metals industry can play a key reinforcing role in the transition by adapting to the increasing supply of renewable electricity. Specifically, direct electrolysis can extract metal from ore close to the thermodynamic limit, to make efficient use of low-C electricity. The unique features of emerging technologies for iron extraction, molten oxide electrolysis and molten sulphide electrolysis are considered in this evolving system. Electrification enables elegant separations and provides a pathway to build out infrastructure while reducing environmental impacts, though material efficiency measures will still be crucial to meet 2050 carbon budgets.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

The nickel metal hydride (NiMH) battery technology has been designed for use in electric vehicles, solar-powered applications and power tools. These batteries contain the critical and strategic raw materials cobalt, nickel and several rare earth elements (REE). When designing a battery recycling process, there are several choices to be made regarding end-products and process chemicals. The aim of this study is to investigate and compare the environmental and economic sustainability of different recycling options for NiMH batteries by taking projected market developments into consideration and by applying life cycle assessment and life cycle costing methods. The comparative study is limited to recovery of the REEs. Two hydrometallurgical processes for recovery of the REEs from the anode material are compared with extraction of REEs from primary sources in China. The processes compared are a high-temperature sulfation roasting process and a process based on hydrochloric acid leaching followed by precipitation of REE oxalates. By comparing the different recycling approaches, the hydrochloric acid process performs best. However, the use of oxalic acid has a large impact on the overall sustainability footprint. For the sulfation roasting process, the energy, sodium hydroxide and sulphuric acid consumption contribute most to the total environmental footprint. This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

This review article provides a comprehensive examination of sustainable extraction and recycling methods for non-ferrous metals, which are critical to a wide range of industries including electronics, construction and renewable energy. Focusing on metals such as aluminium, copper and silicon, the study highlights the importance of recycling in conserving resources and minimizing environmental impact. It discusses the challenges posed by material diversity in recycling processes and the advances in recycling technologies that have emerged in response. Special emphasis is placed on the importance of a circular economy in maintaining a sustainable balance between consumption and conservation of metal resources. Through detailed analysis, it advocates innovative recycling practices and improved design for recyclability and highlights the role of policy, industry and consumer behaviour in achieving sustainability goals. The findings contribute to the discourse on strategic self-sufficiency in Europe through recycling, providing insights into how to improve efficiency and manage the complexity of the global material cycle. This work calls for a collaborative effort towards sustainable metallurgy and underlines the critical need for advances in recycling infrastructure and technology to ensure the long-term availability and environmental stewardship of non-ferrous metals.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

Active learning comprises machine learning-based approaches that integrate surrogate model inference, exploitation and exploration strategies with active experimental feedback into a closed-loop framework. This approach aims at describing and predicting specific material properties, without requiring lengthy, expensive or repetitive experiments. Recently, active learning has shown potential as an approach for the design of sustainable materials, such as scrap-compatible alloys, and for enhancing the longevity of metallic materials. However, in-depth investigations into suited best-practice strategies of active learning for sustainable materials science are still scarce. This study aims to present and discuss active learning strategies for developing and improving sustainable alloys, addressing single-objective and multi-objective learning and modelling scenarios. As model cases, we discuss active learning strategies for optimizing Invar and magnetic alloys, representing single-objective scenarios, and more general steel design approaches, exemplifying multi-objective optimization. We discuss the significance of finding the right balance between exploitation and exploration strategies in active learning and suggest strategies to reduce the number of iterations across diverse scenarios. This kind of research aims to find metrics for a more effective application of active learning and is used here to advance the field of sustainable alloy design.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

Global production of steel and aluminium is a major driver of greenhouse gas emissions. Various processes might allow continued primary production of the two metals, but all depend on emissions-free electricity or carbon storage, and global capacity of these two key resources will be below demand for decades to come. As a result, zero-emissions steel and aluminium will mainly come from recycling, but supply will be lower than demand. This motivates demand reduction, and for the first time, this article estimates the inefficiency in current metal use by component type. The results demonstrate that around 80% of steel and 90% of aluminium liquid metal produced today may be unnecessary. Around 40% of liquid steel and 60% of liquid aluminium are never used in final components as they are removed along the supply chain of manufacturing. Of the metal that enters final service, approximately one-third could be saved by avoiding component over-specification. A further third could be saved, where the properties of metal are not used to their limits. These results point to specific opportunities for innovation in design and manufacturing technology, of which the highest priority is to re-think the use of sheet metal in construction.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.