Researchers at the University of Newcastle have developed a safe and effective method to recover high-grade silver from end-of-life solar panels without using acid, offering a potential breakthrough for the solar recycling and resource recovery industries.

The new process helps recover more than 97% of the silver from an end-of-life photovoltaic panel within just a few minutes, marking a significant improvement over conventional recovery methods that take several hours and rely heavily on chemical-intensive processes that pose environmental and safety challenges at scale.

The technique combines two mineral processing methods of comminution and flotation.

In the first stage, solar panels are mechanically crushed and ground into fine particles through comminution. This is followed by froth flotation, a separation process that uses water, air bubbles, and a small quantity of standard flotation reagents.

During the flotation, valuable metallic components attach to air bubbles and rise to the surface, while waste materials sink. Unlike traditional approaches, the process does not rely on acids or aggressive chemicals, reducing environmental impact and operational risk.

While froth flotation is widely used in the mining sector to separate valuable minerals from ore, this is believed to be the first demonstration of using flotation to recover metallic silver from recycled, ground solar panels, an outcome previously considered unfeasible by many in the field.

End-of-life solar panels contain silver concentrations in the range of 300 to 500 parts per million, which is comparable to, and in some cases higher than, the cut-off grades used in primary silver mining operations.

The research was conducted over an 18-month period and involved collaboration between two University of Newcastle research centers based at the Newcastle Institute for Energy and Resources.

According to Mahshid Firouzi from the University of Newcastle’s Centre for Critical Minerals and Urban Mining (CRITIUM), the work demonstrates that solar panels and the valuable materials embedded in them do not need to end their life as waste.

Beyond silver, the research team is also investigating the recovery of silicon, which accounts for nearly 90% of the weight of a crystalline solar cell and is a critical input for global solar manufacturing.

Firouzi noted that silver is only the starting point and that similar comminution, flotation, and hydrodynamic techniques could unlock billions of dollars’ worth of metals and minerals currently trapped in urban and mining waste streams.

The project aligns with Research Theme 2 of COEMinerals, which focuses on developing rapid and efficient beneficiation technologies to minimize losses of high-value minerals.

This includes advances in fine-particle beneficiation, the use of biomolecules and reversible addition-fragmentation chain transfer polymers, novel reagent delivery systems, and emerging technologies such as ultrafast agglomeration, enhanced gravity separation, and AI-driven reagent design.

Last May, Scientists at Germany’s Fraunhofer Institute for Solar Energy Systems ISE (Fraunhofer ISE) claimed to have produced silicon heterojunction solar cells with a total silver consumption of 1.4 mg per watt of peak power. This consumption would be one-tenth compared to the current industrial production standard.

In September 2024, Scientists from the University of Camerino developed a novel way of extracting silver from end-of-life solar cells. By combining hydrometallurgical and electrochemical processes, the scientists have reportedly recovered pure silver with an efficiency of 98%.