Novel approach of in-situ nickel capture technology to recycle silver and palladium from waste nickel-rich multilayer ceramic capacitors

Waste multilayer ceramic capacitors (MLCCs) are important secondary resource containing silver and palladium. Current methods of directly recovering precious metals from waste MLCCs have certain deficiencies in terms of environmental protection, recovery efficiency and purity. Capture technology has advantages of high enrichment efficiency and less pollution. Nickel can be used as the capture agent. Therefore, this study proposed a novel approach to recycle silver and palladium from waste nickel-rich MLCCs by in-situ nickel capture technology without adding additional capture agent. SiO2 and Al2O3 were selected as the slag former. Silver and palladium were enriched in the alloy and separated from the slag. The recovery rates of silver and palladium were 98.31% and 98.62% under the optimal conditions. Through the microstructure and component analysis of the alloy, nickel and silver formed two phases and palladium existed in silver phase. Furthermore, the capture mechanism was proposed as the separation process of metals and slag, and alloy formation process. Recycling of slag can be achieved by crystallization. This study proposed a green and efficient process to recycle silver and palladium in waste nickel-rich MLCCs and provided a theoretical basis for capture technology to recycle waste MLCCs. (C) 2020 Elsevier Ltd. All rights reserved.