Cues to Greater Recycling Efficiency - Characterization of a Crushed Mobile Phone by Mineral Liberation Analysis (MLA)

Abstract

In the year 2016 alone, more than 1.35 billion smartphones were manufactured globally. These smartphones contain up to 60 different chemical elements and the summarized metal weight of the 2016 production may have well exceeded 50,000 metric tons. At present, most elements contained in this very complex “mixture” represented by a smartphone have recycling rates well below 50%, and the recycling rates of rare earths, indium, tantalum or gallium are even below 1%. The major challenge of mobile phone recycling is the complex composition of the devices made of many individual components – and the lack of transparent information as to the composition of these components. This is aggravated by the fact that many elements occur in traces only and / or are located in highly complex material composites. To enable more effective recycling of mobile phones, it is thus imperative to characterize the constituent components, the presence of elements in it, as well as their behavior during comminution. In a pilot study, a Nokia mobile phone Model 5228 Type RM-625, crushed with a granulator UG300, was examined by Mineral Liberation Analysis. The analysis of three particle size fractions of the comminuted material was carried out in an automated measurement mode with a grid of energy-dispersive X-ray spectra. A total of 130 different phases were detected during this analysis. More than 100 of these phases occur at levels <1% by weight. This strongly illustrates the very complex composition of smartphones. A comparison of the modal content of the three particle size fractions showed good liberation of certain components and an enrichment of some components in specific fractions. These observations reveal the potential to successfully separate different technical components from one another with the goal to increase the resource efficiency of the recycling process.