Mechanical Recycling of Bulk Moulding Compound: A Technical and Environmental Assessment

The recent EU directive on Waste Electrical and Electronic Equipment (WEEE) mandates ambitious targets for WEEE collection, recovery, and recycling. Ensuring full circularity of plastics, constituting 20-30% of WEEE, becomes pivotal. Thermoset composites like Bulk Molding Compound (BMC), are widely used in the electrical sector, posing unique challenges in end-of-life waste management. In fact, the high content of inert fillers and flame retardants negatively affects the in-cineration for energy recovery, while the thermosetting nature of the resin makes thermal reprocessing impossible. Among emerging alternatives for composite waste management, mechanical recycling is particularly promising due to its low technological complexity, easy scalability, and reduced energy consumption. This method involves milling waste into fine particles for use as fillers in the same material (closed-loop recycling) or in new materials (open-loop recycling). In this study, the effect of closed-loop recycling of BMC is studied from both a technological and environmental perspective. The technological assessment involved the collection and recycling of post-industrial BMC scrap generated by the compression molding of cases for ABB circuit breakers, a process generating up to 15% of scrap, on a yearly average. Parts with a variable recycled content (5 to 10%) underwent tensile, impact, and flammability tests to assess the effect of recycling on the key properties of the material. The environmental study, conducted using Life Cycle Assessment (LCA), aimed to provide data-driven validation of the full-scale implementation of this technology within ABB's supply chain. The results confirm the feasibility of closed-loop recycling for post-industrial BMC waste without compromising product performance up to a 10% recycled content. Moreover, the implementation of such a process could potentially reduce the carbon footprint of the material by up to 16%.