Gold removal from e-waste using high-intensity focused ultrasound

Area of Science:

• Materials Science
• Environmental Science
• Engineering

Background:

• Increasing demand for rare and precious metals (RPMs) in electronics drives technological advancement.
• Virgin mining of RPMs is becoming increasingly difficult and costly due to their scarcity.
• Global generation of over 62 million tonnes of e-waste annually presents a significant recycling challenge.

Purpose of the Study:

• To develop a sustainable and efficient method for gold removal and recycling from electronic waste (e-waste).
• To investigate the use of high-intensity focused ultrasound and water for selective gold layer erosion.
• To align recycling practices with the United Nations Sustainable Development Goal 12.

Main Methods:

• Utilizing an 11.8MHz ultrasonic transducer for imaging and selective gold removal from printed circuit boards (PCBs).
• Employing cavitation induced by focused ultrasound in water to erode the gold layer.
• Controlling gold removal by adjusting the number of ultrasonic bursts and optimizing energy efficiency.

Main Results:

• Demonstrated successful, controlled removal of gold layers from PCBs using ultrasound-induced cavitation.
• Identified optimal conditions for energy efficiency, involving minimal removal of the underlying nickel layer.
• Showcased a greener alternative to traditional pyrometallurgical and hydrometallurgical recycling processes.

Conclusions:

• The developed ultrasonic method offers an environmentally friendly approach to gold recycling from e-waste.
• Selective gold removal reduces the need for extensive downstream processing.
• This innovation contributes to sustainable consumption and production patterns, aligning with SDG 12.