Abstract
Increasingly used today, the light-emitting diode (LED) technology today replaces other technologies and has gained a notable market share. This growth in use implies an increased demand for specific materials used in LED manufacturer, aiming at improved performance of devices. However, most materials used in LED manufacture are considered critical in terms of availability, since they are increasingly sought after by the industry. Chemical elements like gallium (Ga) and indium (In), rare earth elements like yttrium (Y) and cerium (Ce), and precious metals such as gold (Au) and silver (Ag) are used in LED devices. An additional difficulty concerns the methods used to sort and reuse these materials, especially due to the small amounts used. This poses a considerable challenge in the full recycling of LED devices. Research is carried out to develop sorting and recovery methods for critical metals generated during the production of LED devices and at the end of life of these devices. Some of the most important methods developed for this purpose include pyrometallurgical (pyrolysis), hydrometallurgical (acid leaching), and biotechnological technologies (microbial leaching).
