An apparatus for separating hot particles including a plurality of materials having different magnetic properties includes a plurality of permanent magnets arranged in a magnet assembly and configured to create a magnetic flux capable of providing a coercive force on at least a portion of the particles, the magnet assembly being mounted on a stationary shaft, a moving surface proximate the magnet assembly for carrying the particles in a downward path through the magnetic flux while the coercive force attracts the portion of the hot particles toward the moving surface, the moving surface being mounted on a drive shaft supported by a bearing, and an inert gas supply system which supplies inert gas into a gap between the stationary shaft and the drive shaft for cooling the drive shaft and the bearings, and into the magnet assembly for purging the magnet assembly of oxygen.