Metallurgical processes must process diverse input feeds cost-effectively
SMS in its article on recycling says that it is not only the metallurgical challenges that limit recycling rates. To effectively use the material goods of modern life – such as buildings, cars, electrical appliances, and mobile phones – as “urban mines,” a comprehensive infrastructure for collecting, pre-processing, and distributing the scrap is essential.
While primary extraction through mining, although often at low grade, benefits from a large ore volume available at a fixed location with a well-defined mineralogy, urban mines are dispersed over millions of units in private households and industries. Therefore, their “mineralogy” or composition is not well defined.
One of the main challenges is accumulating these millions of discarded products to achieve economically viable recovery while managing the complex composition of these materials. The key challenge of metallurgy is to develop robust processes that can process diverse input feeds cost-effectively with a product-centric approach.
The complexity of metal-bearing end-of-life materials makes recycling challenging. Items such as mobile phones can contain over 70 different elements and compounds, intricately and functionally mixed and combined, making it impossible to achieve 100% recovery of all materials and elements. Losses are inevitable, as dictated by thermodynamics.
The metal wheel for end-of-life products effectively visualizes the challenges of dealing with complex metal-bearing end-of-life materials. It elucidates the interconnectedness of metals in nature and recycling and the resulting effects on the entire metal production and circular economy when these connections are disrupted. The circular economy of metal production and recovery is categorized into metal product sectors, each representing a specific base metal industry. The inner ring of the wheel depicts base metals, while the outer rings show the metals associated with each base metal andchemical processing compatibility, either as recoverable by-products or as non-usable components.
That basically means they remain in residues, whichcannot be processed economically due to theircomplexity, and slags. Metals and compounds thatcan be extracted from intermediate or by-productsin the base metal industry are marked in green inthe wheel, indicating chemical refining compatibility.
Metals shown in yellow can be recovered but arealso prone to losses due to incomplete chemicalcompatibility. Metals marked in blue are lost asresidues, especially when they appear in a segmentwith an incompatible carrier metal (e.g., for reasonsof product functionality).
Achieving an efficient circular economy requires a metallurgical infrastructure that fully integrates all segments of the metal wheel. This approach helps maximize resource efficiency by enabling the production of a maximum number of valuable alloys, materials, and compounds. Additionally, energy recovery becomes crucial when end-of-life material mixtures become too complex. We must understand and minimize entropy creation within our systems, and, in turn, minimize exergy dissipation in our solutions. In simple terms, this means designing processes that create as little waste and energy loss as possible to ensure minimal exergy dissipation.
