New method that recovers up to 97% of silver from discarded solar panels

Recovering most of the silver from discarded solar panels? It can be done! In environmental issues, there are rarely simple solutions: what seems promising today may reveal new problems tomorrow. This is also true for the solar industry, which faces a crucial challenge: dealing sustainably with panels that have reached the end of their life span.

Research from the University of Newcastle in Australia, published November 2024, introduces an innovative method for recovering silver from photovoltaic cells, promising to radically change current recycling processes.

New, less burdensome techniques

Currently, the recovery of silver from discarded solar panels is primarily dominated by acid leaching. While this technique is effective, it requires extensive use of chemical reagents and produces significant amounts of waste - factors that limit its widespread application. In contrast, the new research proposes the use of froth flotation to separate the metallic silver, drastically reducing the environmental impact.

How froth flotation works

The method involves mechanically grinding the panels and then subjecting the finely ground material to flotation: a separation technique that uses water, air bubbles and a minimal amount of standard reagents to float precious metals while the waste material sinks to the bottom. Tests showed that the process is particularly robust and works not only with ultrapure water, but also with ordinary tap water. Under realistic conditions, the team managed to recover 97.60% of the silver, demonstrating the potential industrial applicability of the method.

Results in record time

One of the most striking aspects of this innovation is the speed of the process: about 80% of the silver is recovered within the first 60 seconds and 90% in just three minutes. Moreover, a subsequent purification phase makes it possible to obtain a concentrate containing around 47 percent of silver by weight, making the process not only fast but also highly selective.

The research was led by associate professor Mahshid Firouzi of the University of Newcastle's Centre for Critical Minerals and Urban Mining (CRITIUM). Firouzi emphasized that solar panels and the valuable metals they contain at the end of their life do not necessarily have to end up as waste.

Although froth flotation is widely used in mining to separate valuable minerals from ore, to our knowledge this is the first demonstration of froth flotation for the recovery of metallic silver from recycled and ground solar panels - something many in the industry believed was not feasible, estimates associate professor Firouzi.

A step forward for the circular economy

The use of froth flotation can dramatically change the logistics of recycling solar panels, thanks to a sharp reduction in reagents, waste and environmental impact, as well as the efficient recovery of valuable materials.

(MP/©ResearchGate via GreenMe.it/translation and adaptation: The Global Nature/Illustration: Harisankar for Unsplash)