Recovery of silver from waste printed circuit boards (WPCBs) through hydrometallurgical route: A review

The modernization of technologies has led to the escalation of the demand for silver in the electrical and electronics manufacturing sectors. Conventional lean grade ores of silver are insufficient to account for silver consumption. This deficit compels the extraction engineers to broaden the scope and delve into secondary silver recovery and recycling. The key purpose of current work is to draw attention to the modern hydrometallurgical technologies in silver recovery from waste printed circuit boards (WPCBs). Abundant with the base and precious metals, WPCBs form a plethora of important materials and the efficient recycling of WPCBs is essential for economic and environmental reasons. Low capital cost, high selectivity, no dust generation and reduced environmental effect advocate the versatility of hydrometallurgical route. Silver leaching from WPCBs through cyanide, thiourea and thiosulfate have been investigated. Cementation, ion exchange, solvent extraction, and membrane processes employed for recovery of silver have been studied. This review provides a holistic view of the significant technological advances throughout the world to recover silver from the WPCBs by hydrometallurgical route