Bead Mill for NdFeB Magnet Recycling: Grinding Rare Earth Powder Back Into New Magnets. NdFeB (neodymium-iron-boron) magnets can be recycled "magnet-to-magnet" — ground back into fine alloy powder and resintered into new magnets — rather than only recovered as raw rare earth chemicals. Hydrogen decrepitation (HD) is the standard pretreatment step: exposing scrap magnets to hydrogen gas causes internal cracking that reduces bulk magnet to a friable powder in the 6–600 µm ra