Cell-Phone Recycling by Solvolysis for Recovery of Metals

摘要

Mobile phones represent a significant and growing problem with respect to electrical waste and electronic equipment (WEEE). Nevertheless, they are perhaps one of the most valuable electronic products, since they are an important resource for the recovery of metals in terms of mass and volume. In this research a chemical recycling of mobile phones by solvolysis was investigated. The processing was performed by comminution in a hammer mill followed by screening to obtain mesh-4 sized flakes. Flakes were subjected to solvolysis. Different reaction conditions were tested. A reaction time between 2 - 7 hours and a temperature between 150°C - 300°C were the optimum conditions to dissolve the polymer contained in mobile phones. Metals were separated by filtration. Chemical analyses (ATR FT-IR, UV) were carried out on the solvent and the mobile phone flakes before and after solvolysis. A SEM study was carried out, before and after solvolysis, but only to the mobile phone flakes. Thermal transitions of mobile phone flakes were determined by DSC. Chemical results showed that some aromatic species migrate from mobile phones flakes to the solvent, due to the solvolysis reaction. Thermal analysis showed that the Tg, (glass transition temperature) of mobile phone flakes after solvolysis was different to Tg of the polymer before solvolysis, this is due to chemical changes in the molecule. A comparative SEM study revealed that, after solvolysis, the polymer contained in mobile phone flakes is more elastomeric. After solvolysis, solvent was recovered by means of a rotatory evaporator, so that it can be used again. The results obtained in this research showed that solvolysis is an alternative for metal recovery from mobile phones.