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 fluidized bed type electrically charging apparatus and, after charging, classified and extracted in an electrostatic apparatus to be classified into specific components.

CONSTITUTION: A raw coal fine powder is sent into a fluidized layer type charging apparatus along with drying air from an inlet 118. The inside of the charging apparatus is partitioned into a stirring chamber 113, a first and a second fluidized layer chambers 114, 115 by an earthed perforated plate 112 and, to the central part thereof, a powder discharge pipe 116 is provided. The powder is succeedingly passed through the stirring chamber, the first and the second fluidized layer chambers along with drying air introduced from an inlet 119 under pressure but, during this time, receives repeated friction with particles G1, G2 preliminarily received in those chamers to be charged and, after charging, is introduced into a cyclone part above a discharge pipe from a collecting port 120 and the gas component is discharged from a discharge port 117 and the powder is fallen into an electrostatic classification apparatus having electrode plates 121, 122 between which D.C. electric field B is imparted. By this action of the electric field, the positively charged high carbonaceous component, the negatively charged ash component and the mixed component with reduced polarity therein are respectively classified into collecting ports 124a, 124c and 124b.