Innovative method for the recycling of end-of-life LED bulbs by mechanical processing

Technological development has led to increasing quantities of waste electrical and electronic equipment. At the same time, the search for more efficient uses of energy is an urgent current issue. Both problems have relations to LED bulbs. The presence of hazardous and valuable materials in these bulbs makes their recycling essential. However, due to the many different parts that compose an LED bulb, the separation of LEDs from the bulbs is difficult, but is crucial for proper recycling. This work describes a recycling process for LED bulbs solely using mechanical processing. Firstly, the LED bulbs were dismantled and their components were characterized in terms of their weight and by DSC and SEM/EDS analyses. Then, operations including comminution, sieving, electrostatic separation, magnetic separation, and gravity separation were applied to separate the LED bulb components, according to their characteristics. The operations were adapted in order to achieve the maximum possible separation of the components. A mechanical processing flowchart was proposed for LED bulb recycling. Characterization of LED bulbs revealed the presence of polymers and valuable and/or hazardous materials including copper, silver, and lead. The results showed separation efficiencies in the range 98-100% for many components (polymeric cover, metallic housing, Edison screw, PCB, and heat sink with LEDs). A simplified economic analysis of the recycling process showed it to be feasible, with estimated profit of US$ 639.82/ton of processed LED bulbs. The results indicated that the proposed mechanical processing was highly effective for the recovery of materials at high purity from LED bulbs.