MEMRECS—A Sustainable View for Metal Recycling from Waste Printed Circuit Boards

Abstract

This study analyses the metal recyclability from waste Printed Circuit Boards (PCBs) with three material recycling quoting approaches: Material Recycling Efficiency (MRE), Resource Recovery Efficiency (RRE), and Quotes for Environmentally Weighted Recyclability (QWERTY). The results indicate that MRE is likely inapplicable to quoting the metal recyclability of waste PCBs because it makes the recycling of any metal equal to each other (e.g. recycling of 1 kg of gold is as important as recycling of 1 kg of iron). RRE and QWERTY can overcome the poor yardstick of MRE because they concern not only the weight of recycled materials but also the contribution of recycled materials to the natural resource conservation and the environmental impact reduction, respectively. These two approaches, however, report an extremely different result, that makes the target stakeholders get confused with which material recycled. From the findings of the aforementioned analysis, this study proposes the Model for Evaluating Metal Recycling Efficiency from Complex Scraps (MEMRECS) as a new approach to quotes the metal recycling performance. MEMRECS allows the trade-offs between three criteria: mass, environmental impacts and natural resources conservation, hence it can provide the result in a sustainable sound manner. MEMRECS clearly models and enhances the role of natural resources conservation aspect rather than QWERTY does.

Recycling Tin from Electronic Waste: A Problem That Needs More Attention

“…There are ∼23 different types of naturally occurring tin minerals, but only cassiterite is economically feasible to mine and recover. The grade of tin in ore is ∼0.2–1.5%. − Although the content of tin in waste PCBs is ∼1–6%, the average value is ∼4%. − Cassiterite is concentrated from tin ore using jigs, spirals, shaking tables, centrifugal concentrators, and froth flotation. Approximately 50–60% of cassiterite is recovered using gravity concentration.…”

What Is ‘Value’ and How Can We Capture It from the Product Value Chain?

“…Again simplicity is the goal of this indicator. Other methods of assessing recyclability tend to focus on the environmental responsibility of recycling, but less the economic advantages [20][21][22]. Furthermore, other indicators often include efficiency of the recycling system in recovering the metal.…”

“…The phone is modelled as consisting of a subset of components including the main PCB, mounted with processor and memory ICs, the display (LCD), the battery, antenna and the metal case. The component weights and compositions are based upon a Fairphone [25] with supplementary data for PCB [22], battery [26] and LCD [27] composition used where appropriate. The antenna and LCD are assumed to contain a PCB and ICs as part of their construction.…”

Evaluation of US EPA Method 3052 Microwave Acid Digestion for Quantification of Majority Metals in Waste Printed Circuit Boards

“…Three main types of recyclable materials can be retrieved from PCBs: metals (mainly Cu, Al, Sn and Pb) and precious metals (Au, Ag and Pt), polymeric materials and ceramic materials [8]. Each metal occurring in PCBs has its own specific properties depending on the particular point of view, such as weight share, economic value, environmental impacts, or natural resources depletion [9].…”