PURPOSE: To omit or simplify muddy waste water treament and dehydrating and drying stages by fluizing the particles of fine powder, charging these particles electrostatically with an electrostatic charging sieve, passing the same through an electric field and separating these by the electrical properties of the particles.

CONSTITUTION: The pulverized coal which is ground and dried is mixed with a non-combustible gas and is blown into an electrostatic charger from a flowing ports 25. Since the charger has a net electrode sieve 26 and a ground electrode 28 supported by supporting insulators 26A, 26B in an insulating vessel 24, and pulverized coal is controlled of grain sizes with the sieve 26, an at the time when it detaches from the electrode 28, it is induction-charged. The charged powder is fed into an electrostatic separator. The separator generates a DC electric field between electrode plates 31A and 31B facing each other. Since this electric field is moved by applying multiphase AC voltages to an electrode plate 32, the charged powder is separated under conveyance according to the respective polarities and charge quantity and is conducted to capturing pipe 33W35.