Recovering materials from waste mobile phones: Recent technological developments

Due to the vast consumption and shortened lifespan of mobile phones, waste mobile phones (WMPs) have become one of the fastest-growing global waste electrical and electronic equipment (WEEE) streams. Although the recycling potential of WMPs is well-recognized, the current recycling rate remains low, jeopardizing the sustainability of both the environment and mobile phone industries. With the objective of identifying limitations in the current method developments that hinder WMP recycling, we review the material recovering technologies for WMP recycling, published in academic journals and/or conferences between Jan 2005 and Apirl 2019. Most WMP recycling processes have been developed to recover precious metals (such as gold and silver) from mobile phone printed circuit boards (PCBs), via acid leaching processes. However, pre-treatment and separation steps required to concentrate the waste stream for efficient extraction are often overlooked. In addition, to separate the individual components of the WMP, most recycling methods use manual disassembly as their first step, a practice which is not suitable for scale-up. Generally, particle size ranges used in laboratory trials are smaller than those used in current industrial practice, as it is not economically feasible to acquire such small particle sizes industrially. There is a current trend to replace the inorganic acids used for metal leaching with more environmentally-friendlier lixiviants, however, industrialization of these approaches is not economically viable. This review serves as a guidance for future research and development in this area, providing information to facilitate WMP management.