Rethinking Silver Recovery Pathways in End-of-Life Photo Voltaic Recycling Using Froth Flotation

Current research concerned with recovering silver from end-of-life (EoL) photovoltaic modules is dominated by acid leaching which, while effective, imposes substantial reagent and waste burdens that impede large-scale deployment. This work presents, for the first time, the application of froth flotation as an upstream selective recovery step for extracting metallic silver from EoL PV cells. Method development was undertaken in a 0.5 L mechanical cell, followed by 1 L tests in ultrapure water to evaluate robustness and scale effects under matched hydrodynamics. Experiments used delaminated cells sourced from waste panels with AEROFLOAT 242 and AEROPHINE 3418A at 150 g/t of dry feed. To assess industrial relevance and water-quality sensitivity, the rougher flotation was repeated using tap water, resulting in silver recovery of 97.60 ± 0.03% and upgrade of 32.2 ± 2.3, demonstrating strong reagent compatibility under realistic water chemistry. For a controlled baseline, the 1 L rougher flotation in ultrapure water delivered 91.31 ± 0.61% recovery and upgrade of 33.8 ± 3.5. Kinetic data indicated a fast response, about 80% recovery within 60 s and about 90% by ~3 min, with minimal improvement beyond 3 min. These results indicate pre-concentration by flotation can drive substantial downstream savings: only ~2.8% of the original feed reports directly to leaching for the 3-minute rougher in tap water (about 35 times less mass than direct leaching). A closed circuit or a plug-flow-type cell could provide additional cleaning in practice. As an illustration, adding only a cleaner stage downstream of the rougher flotation in ultrapure water increased the upgrade to 62.6 ± 2.0 at 86.5 ± 2.8% recovery, producing a concentrate of ~47 wt% Ag. These results demonstrate a viable beneficiation route for critical-material recovery from secondary resources, supporting circular-economy objectives with lower reagent intensity and smaller processing footprint.