Researchers at the University of Newcastle have developed a method for recovering almost 100 percent of the silver from used solar panels without using acids.

The scientists conducted the world’s first continuous industrial-scale trial for recycling photovoltaic waste using flotation technology.

During the 90-minute trial, specialists processed approximately 22 kilograms of material obtained from around 468 kilograms of old solar panels. Almost all of the silver was successfully separated from the other components.

The method uses water, air, and a small amount of specialized reagents. Silver-containing particles attach to air bubbles and rise into the foam, where they are collected as a concentrate.

The process operates at normal temperatures and does not require large volumes of acids.

During stable operation of the system, the silver was concentrated by approximately 83 times. The resulting concentrate contained an average of 48.8 percent silver by mass, while in most waste samples, the silver concentration was below the detection limit.

The technology could reduce the cost of recycling solar panels by three to five times compared with acid leaching.

This is particularly important for Australia, where more than one million tonnes of used solar panels are expected to accumulate by 2050, containing an estimated 300 to 500 tonnes of silver.

The researchers plan to investigate whether the method can also be applied to other types of electronic waste, including printed circuit boards from data-center equipment.