Metal recovery from industrial solid waste by ultrasonic-assisted hydrometallurgical leaching: a review

In the context of the circular economy, there is a need for advanced methods to recover metals from industrial waste, yet classical hydrometallurgical techniques are limited. Here, we review ultrasonic-assisted hydrometallurgical leaching with focus on the use of acids, bases, oxidants, bacteria and electrolysis. Oxidative leaching is done with ferric ions, dioxygen, ozone and hydrogen peroxide. Upscaling is also detailed. Ultrasonication allows to reduce the dosage of leaching agents, to reduce reaction time, and to enhance leaching efficiency. Large-scale equipments are still limited by low cavitation efficiency, low throughput, high usage costs, and high energy consumption.