Environmental footprint analysis of gold recycling from electronic waste: A comparative life cycle analysis

Abstract

While e-waste poses significant environmental and health risks, it also harbors valuable metals like gold, ripe for recycling. However, extracting gold from e-waste carries its own ecological footprint. Therefore, employing tools like Life Cycle Assessment (LCA) to evaluate environmental impacts and identify mitigation measures is imperative. This research addresses critical gaps in the literature surrounding gold recovery from e-waste. It covers a range of methods, including hydrometallurgical and pyrometallurgical (well-established) to mechanical and biotechnological (less explored for gold recovery), rectifying the imbalance in methodological attention. This study also prioritizes environmental assessment, elevating LCA to a central investigative focus for understanding the sustainability of gold recovery from e-waste. Notably, there is a paucity of consistent and systematic comparisons between diverse gold recovery methods from e-waste in existing literature. While some publications touch on environmental aspects, comprehensive LCA investigations are lacking. Thus, this research explicitly bridges this gap through a comparative LCA, evaluating mechanical, hydrometallurgical, pyrometallurgical, electrochemical, and biotechnological methods and contrasting them with conventional mining (baseline method). The results highlight significant reductions in damage to human health, with the mechanical and electrochemical methods leading the way with a noteworthy 98% reduction compared to the baseline. The hydrometallurgical and pyrometallurgical methods also demonstrate substantial decreases of 83% and 92%, respectively. Though the biotechnological method exhibits a comparatively lower reduction of 60%, it represents a significant advancement in curbing damage to human health. Regarding ecosystem quality, the mechanical and electrochemical methods excel with exceptional reductions of over 99%, while the biotechnological, hydrometallurgical, and pyrometallurgical methods collectively achieve a decrease of approximately 99% compared to the baseline. Across the board, all evaluated methods manifest substantial reductions in total weighted environmental impacts, amounting to an approximate 99% reduction. The biotechnological method does entail the highest exergy demand, signifying greater energy consumption, while the mechanical method demonstrates the lowest exergy consumption. Considering feasibility and scalability, the electrochemical and mechanical methods emerge as the most favorable options for sustainable gold recovery. These methods demonstrate promising results in reducing environmental impacts and are well-suited for practical implementation.