2014 Volume 55 Issue 3 Pages 616-621
Recovery of rare earth metals from bond magnets has been investigated by means of thermally activated semiconductors (abbreviated to TASC). TASC is a novel technology developed recently by us, allowing to decompose any organic materials including polymers in an instant into H2O and CO2. This technology has been utilized in the present investigation to reclaim rare earth metals from bond magnets by removing only polymer binders while retaining mostly the original composition of magnets. The TASC technology is based on our accidental finding that the semiconductor exhibits significant oxidative catalytic effects when heated at about 350–500°C. The initial process of the polymer decomposition is the capture of bonded electrons to create cation radicles in polymers. Then, the unstable radicles propagate throughout the polymer chains to make the whole polymer unstable, resulting in the fragmentation of the polymer into tiny molecules such as ethylene, propane etc. These fragmented molecules end up with reaction with oxygen in air to give rise to H2O and CO2. In this way, rare earth metals are successfully reclaimed from bond magnets in about one–two hours in the form of powders.