Liberation of Printed Circuit Assembly (PCA) and dust generation in relation to mobile phone design in a size reduction process

Complex electronic devices entering our recycling systems often generate losses in the whole treatment chain. For better liberation, crucial for the mechanical separation process, the devices are crushed which also generates dusts that are not recovered. This study investigated the relation between the liberation of Printed Circuit Assembly (PCA) and dust generation in the crushing process of two different types of mobile phone samples. The results revealed that the overall PCA grade in both samples was approximately 70% with around 3.4% dust generation. However, the liberation distribution of PCAs differed between mobile phones resulting in better distribution for sophisticated mobile phones due among other things to the initial size of the phones. Further, the dust fractions comprised both noble and valuable metals but also contaminants that need to be taken into account when further processing is planned. A higher gold concentrate was detected in dusts from regular phones since the protective plastic casing crushed more easily thus exposing the PCA surface for grinding.