PURPOSE: To eliminate or simplify a sludge treatment, a dehydrating and a drying processes by a method wherein a powder mixture comprising two kinds or more of components is charged in a cyclone type electrically charging apparatus and, after charging, selected and extracted in an electrostatic classification apparatus into specific components.

CONSTITUTION: A raw coal fine powder is sent into a cyclone from an inflow port 111a along with drying air. To the inside of a cyclone main body 111, a funnel like core having plural transversely elongated pores 112a toward the peripheral direction thereof is provided. The inflow powder receives cyclone action and the gas therein is discharged to a discharge port 11b and the powder component to a discharge port 111c. In this case, the powder generates violent friction with the inner wall of the main body and the core 112 to be charged. The charged powder is introduced into an electrostatic classification apparatus having electrode plates 121, 122 between which a D.C. electric field B is imparted and, by the action of said electric field, the positively charged high carbonaceous component, the negatively charged ash component and the mixed components with reduced polarity therein are respectively classified into collecting ports 124a, 124c, 124b to be respectively recovered as a product, a waste material and a reselected part.