Keywords:industrial ecology printed circuit board (PCB) recycling resource recovery substance flow analysis (SFA) waste electrical and electronic equipment (WEEE) SummaryThe manufacturing of electronic and electrical equipment (EEE) is a major demand sector for precious and special metals with a strong growth potential. Both precious and special metals are contained in complex components with only small concentrations per unit. After the use-phase, waste electronic and electrical equipment (WEEE) is an important source of these "trace elements." Their recycling requires appropriate processes in order to cope with the hazardous substances contained in WEEE and to recover efficiently the valuable materials. Although state-of-the-art preprocessing facilities are optimized for recovering mass-relevant materials such as iron and copper, trace elements are often lost. The objective of this article is to show how a substance flow analysis (SFA) on a process level can be used for a holistic approach, covering technical improvement at process scale, optimization of product life cycles, and contributing to knowledge on economy-wide material cycles. An SFA in a full-scale preprocessing facility shows that only 11.5 wt.% of the silver and 25.6 wt.% of the gold and of the palladium reach output fractions from which they may potentially be recovered. For copper this percentage is 60. Considering the environmental rucksack of precious metals, an improvement of the recycling chain would significantly contribute to the optimization of the product life cycle impact of EEE and to ensuring the long-term supply of precious metals.

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A fundamental metric for the assessment of the recyclability and, hence, the sustainability of coated magnesium scrap is presented; this metric combines kinetics and thermodynamics. The recycling process, consisting of thermal decoating and remelting, was studied by thermogravimetry and differential thermal analysis (TG/DTA) experiments and thermodynamic simulations. Decoating phenomena are interpreted using kinetic analysis, applying existing reaction models. The derived kinetic model parameters ln A and E a /(RT p ) are used to characterize the decoating process. The impact of inorganic coating components on remelting is quantified using exergy. Oxidation and entrapment losses, quality losses, and material resource depletion caused by the inorganic components are expressed in exergy units and combined into the single parameter R. Based on the results, the coating characteristics favorable for recycling are derived. The obtained metric is a three-dimensional (3-D) combination of ln A, E a /(RT p ), and R, which represent the decoating velocity, the ease of decoating, and the impact of coating materials on the remelting process, respectively. The metric, therefore, directly links coating characteristics, coating design, and product design with process technology and recyclability, enabling the ranking of coating alternatives in terms of their respective recyclability. Therefore, the key idea of this article is to use fundamental metallurgical theory to express the recyclability of postconsumer scrap in a unique combination of parameters. This should pave the way for ranking the sustainability of different materials.