PURPOSE: To remove powder from grains by electrical repulsive force efficiently by providing a corona discharge electrode and a counter electrode at a part for regenerating grains coated with powder to generate corona discharge.

CONSTITUTION: An electrically conductive mesh 14 to be used as a counter electrode is arranged opposite to a discharge electrode 13 in a vessel 12 in a regeneration part. Meanwhile, grains 16 coated with electrically conductive powder 15 are continuously dropped and the grains 16 are moved downward along the conductive mesh 14. At this time, a high voltage is impressed between the discharge electrode 13 and the conductive mesh 14 by an electric power source 17. Consequently, electrical repulsive force is generated between fine particles of the powder 15 and between the grain 16 and the powder 15. Accordingly, the conductive powder 15 is released from the grain 16 before reaching the bottom part of the vessel 12, passed through the conductive mesh and the accumulated under the mesh. The grains 16 are accumulated in another space separated by a partition plate 18.