From scraps to solutions: Improving metal recycling - Interesting Engineering

From scraps to solutions: Improving metal recycling
From scraps to solutions: charting progress in metals recyclingRead on to find out how new metal recycling techniques are creating a sustainable path to a greener future.Tejasri Gururaj| Sep 25, 2023 01:44 AM ESTCreated: Sep 25, 2023 01:44 AM EST innovationHow can we make metal recycling more efficient?Gary Kavanagh Get a daily digest of the latest news in tech, science, and technology, delivered right to your mailbox. Subscribe now.By subscribing, you agree to our Terms of Use and Policies You may unsubscribe at any time.Metal recycling and reuse has often taken a backseat to the recycling of other materials.Yet virgin metals are a huge source of greenhouse gas emissions.Luckily, progress is beginning to be made.We live in an era defined by an urgent need for sustainable practices. While strides have been made in various sectors, the recycling of metals—essential components in everything from towering skyscrapers to everyday utensils—has remained relatively stagnant.Billions of tons of metal are mined annually, with metal production accounting for around 8% of global greenhouse gas emissions. Yet, unlike many other materials, metals do not lose their integrity when recycled repeatedly, making them an ideal candidate for recycling and reuse.Although around 70 per cent of US and 55 per cent of European steel production is already based on recycled steel, many other metals are not recycled as commonly. However, many companies across the world are starting to take up the challenges of metal recycling and are beginning to make progress. In this article, we take a look at various aspects of the metal recycling process and some of the key players in this industry. We will also gain some insights from Annanya Agarwal, the CEO and Co-Founder of Runaya, a metal recycling startup based in India. How metals are recycledMetal recycling follows a series of steps that ensures efficient utilization and conservation of resources, reducing the need for extraction of ore.Collection: Gathering the building blocksThe first step is collecting the metal for recycling. Scrap yards incentivize individuals and businesses to contribute to recycling, promoting responsible waste management and resource conservation.Various steps involved in the metal recycling process.Cohen Recycling Online platforms that make scrap metal trading easier, such as MetCycle, are used to connect verified buyers and sellers of scrap metal, allowing both to benefit from direct negotiation, with better prices, better margins, and time savings. SortingOnce collected, metals undergo sorting to distinguish recyclable from non-recyclable materials. High-quality recycling hinges on this step. Advanced technologies, such as magnetic systems, X-rays, and infrared scanning are used to help with the accurate categorization of different metals.Processing and shreddingAfter sorting, metals are compacted and shredded to optimize processing. Smaller pieces offer a higher surface-to-volume ratio, facilitating efficient melting. Steel is generally transformed into blocks at this stage, while aluminum is converted into sheets, setting the stage for downstream processes.However, shredding can often be challenging due to the abrasive, heavy, and usually bulky nature of certain metals. A recent advance is the use of a single, high-quality shredder that can tackle heavy metals like brass, copper, and bronze, as well as lighter metals like magnesium and aluminum.Melting and purificationThe shredded metal is then subjected to intense heat and melted in specialized furnaces designed for specific metals. The melted metal is then purified, removing impurities to ensure high-quality recycled materials. Different purification methods, including electrolysis and magnetic separation, contribute to producing clean, usable metal. Scientists have also been to better understand processes used in purification. Liquid-to-liquid extraction is the basic process used in hydrometallurgy for recycling metals. However, until recently, the way this works has been poorly understood.In a 2020 paper, Thomas Zemb and a team of researchers from the Institut de Chimie Séparative de Marcoule in France, recently quantified, for the first time, the efficiency of the extractant molecules in the process, and the synergy between them, in what the researchers call the ienaics approach. They also patented a new method for extraction, using a family of chemicals that had not previously been used in recycling. The approach reduces the quantities of fluid used in metal purification, along with the amount of effluent produced, enhancing metal purification and recycling efficiency.Metal shavings in close-up.Pridannikov Solidification and transportMolten metal is solidified in cooling chambers, taking on new shapes and sizes to meet diverse manufacturing needs. Once shaped, the recycled metal is packaged and transported to factories, contributing to the creation of a closed-loop cycle.Technological advancements The metal recycling industry faces challenges that demand innovative solutions. One such challenge is dross management—a critical concern in aluminum recycling. Aluminum dross, a byproduct of smelting, presents a disposal dilemma, contributing to environmental hazards and resource wastage. Conventional methods are not good at efficiently recovering aluminum from dross, exacerbating the issue.Runaya's focus is on aluminum recovery, and they have a three-stage process to tackle the problem of aluminum dross. Explaining this, Agarwal said, "One of the biggest challenges is aluminum dross management. Globally, over 60% of one million tons generated annually is unethically disposed.""Runaya and Taha International developed India's first zero aluminum dross smelter. Processing approximately 40,000 metric tons in Odisha and Chhattisgarh, we recover 40% aluminum, emitting 0.7 tons carbon dioxide per ton aluminum, certified and four to five times lower than traditional [methods]."A close-up of aluminum dross, a major waste challenge faced in metal recycling.Nbritton/Wikimedia Commons The first two steps of the process involve recovering aluminum from dross without using extra energy. The recovered aluminum is reused, while residual oxides find use in other applications, achieving a zero-waste solution."The remaining 60% creates value-added products, following our green mission. Restore Ultra, jointly launched by Runaya and Vedanta, offers aluminum with an ultra-low carbon footprint, certified by DNV for GHG emissions. Solar-powered operations and Ultra Green Briquettes showcase our commitment to environmental sustainability and 100% waste utilization," he concluded. Apart from advances in dross management, the industry has also benefitted from sorting systems equipped with artificial intelligence (AI), sensors, and cameras. For example, ZenRobotics manufactures a fully automated robot for use in sorting. It comes fully equipped with metal detectors, AI, 3D laser technology, and spectroscopic imaging.Urban mining is also gaining traction as a vital means of metal recovery from urban waste, driven by growth, environmental concerns, and market potential.Urban mining is key for a shift to a circular economy.Holcim A study led by Zhi Sun, from TU Delft, evaluated waste streams using resource and technology indices. This approach identified promising categories like information and communication technology (ICT) scrap and rare-earth element (REE)-containing end-of-life products for advancing recycling technologies.Energy-efficient processing methods, such as microwave-assisted recycling and advanced electric arc furnaces, are also significantly reducing energy consumption and emissions. In fact, a study led by Jing Sun, from Shandong University in China, found that microwave-assisted treatment of spent graphite can yield various valuable materials, including graphene and its derivatives, with potential applications in energy storage, catalysis, sensors, and other fields.Technological advancements are the key to improving rates and efficiency of metal recycling. As highlighted by Agarwal, “We have experienced a range of benefits as a result of our commitment to technological advancements, such as improved productivity, optimized resource utilization, enhanced safety measures, seamless operations, and strengthened control systems. Additionally, our focus on innovation has led to improved asset life, ensuring long-term sustainability.”The changing landscapeDespite its somewhat slow progress, a growing number of innovative companies are leading the way in increasing the rates and efficiency of metal recycling and contributing to the creation of a circular economy.For example, recycled metal is commonly used in architecture, especially steel. Around 86% of structural steel is recycled as scrap charge used in furnaces while around 13% of architectural steel is dismantled and used directly for new structuresRecycled metal is even being used in art. 60 Second Docs via GIPHYOther innovative metal recycling processes include the recovery of aluminum from coffee pods and production of personal care products like razor blades out of recycled metals. Embracing the circular economyThe concept of a circular economy has gained momentum as a transformative approach to resource management. In contrast to the traditional linear take-make-dispose model, a circular economy promotes the continuous use and regeneration of materials, aiming to minimize waste and maximize resource efficiency.Several industries are adapting this approach to reduce waste and promote sustainable practices. We see companies like Redwood Materials, which focuses on a circular supply chain for lithium-ion batteries. They collect, recycle, and reprocess battery materials to create a closed chain, reducing the need for new raw materials and minimizing environmental impact.This is supported by recent research that underscores the pivotal role of advanced circular economy systems and sophisticated recycling technologies in fostering a resource-efficient and sustainable society.A study by Christian Hagelüken and Daniel Goldmann found that closed metal cycles emerge as a significant contributor by ensuring a stable supply of essential raw materials for high-tech products and concurrently curbing carbon dioxide emissions during production.The rise of urban mining also highlights the need for waste management, logistics, and recycling experts. Digitalization and principles like the shared economy, coupled with cross-sectoral collaboration, are crucial for advancing the circular economy and transitioning toward a sustainable society.Collaboration among stakeholders, including businesses, policymakers, and consumers, underpins the circular economy's advancement, fostering a resilient and eco-conscious society.ConclusionAs the imperative for sustainable practices intensifies, nations around the world are stepping up their efforts in metal recycling to combat resource depletion and environmental degradation. NewtownCreekAlliance via GIPHYA notable example is South Korea, which imports 99% of its mineral metal resources. In response, the Korean government launched the Valuable Recycling Project in 2011, a 10-year initiative to develop efficient recycling technologies to enhance resource recycling ratios and meet international environmental standards. Explaining the significance of recycling and the circular economy, Agarwal said, "We came to realize that approximately 40% of the 100 billion tons of industrial waste generated each year undergo processing, while the remaining 60 billion tons are relegated to landfills or unethical disposal practices."Runaya's aluminum recovery process has been successfully implemented at Vedanta's Aluminium Smelters.Runaya Additionally, the engineering sector plays a crucial role in advancing metal recycling efforts. Agarwal underscores key steps engineers can take, including raising awareness about recycled metals, optimizing supply chains, and prioritizing sustainable materials. Collectively, these measures represent a united front in the pursuit of sustainable metal recycling and a greener, more resilient future. 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