Researchers at the University of Newcastle have successfully completed a continuous pilot-scale trial of an innovative, acid-free method for extracting silver from decommissioned solar panels. By utilizing mechanical crushing followed by froth flotation, the team achieved a recovery rate of nearly 100% of the silver content. This process concentrates the valuable metal into a small fraction of the original material weight, offering a sustainable alternative to traditional chemical-intensive recycling. The breakthrough represents a significant step toward commercial viability, potentially lowering recycling costs and addressing the environmental challenges posed by the growing volume of end-of-life photovoltaic modules.
The recycling of crystalline silicon solar cells has long been hindered by the difficulty of isolating silver, which is the most valuable component within the modules. Conventional recovery techniques often rely on harsh acids that produce hazardous waste, complicating the disposal process. The new approach developed by the Australian research team adapts froth flotation—a technique standard in the mining industry—to separate silver particles from the rest of the solar cell components using only water, air, and minimal amounts of reagents.
During the pilot trial, the researchers processed approximately 22 kilograms of solar-cell material derived from roughly 460 kilograms of end-of-life panels, which equates to about 23 residential modules. The mechanical comminution process grinds the panels into fine particles, which are then treated to ensure silver-bearing material adheres to air bubbles and rises to the surface. This method successfully concentrated the silver into a product representing just 1.25% of the original feedstock, with a silver concentration more than 80 times higher than the starting material.
Associate Professor Mahshid Firouzi, Deputy Director of the University of Newcastle’s Centre for Critical Minerals and Urban Mining, noted that the transition from small-scale batch experiments to continuous operation is a critical milestone. Previous laboratory tests had already confirmed recovery rates exceeding 97% within minutes, but the pilot trial proves the technology can function at a larger scale. This advancement brings the process significantly closer to industrial adoption.
From an economic perspective, the flotation-based method shows promise for improving the financial feasibility of solar panel recycling. Preliminary assessments indicate that this process could be three to five times cheaper than conventional acid-leaching techniques. Currently, recycling a solar panel in Australia costs between AUD 10 and AUD 15, which is significantly more expensive than sending the units to a landfill. The researchers anticipate that the revenue generated from the high-purity recovered silver will help bridge this price gap, encouraging more widespread adoption of sustainable recycling practices for aging solar infrastructure.