Method for industrial processing of charcoal ash (1) created in the power plants by separating a carbonaceous product from the mentioned charcoal ash to be reused and by gathering essentially carbon free, siliceous ash products gained during the processing. Li the method charcoal ash (1) is directed to the foaming process (11, 6a) in which process ash contents containing silicate and coal are separated by using water as an intermediate agent in which case the separation is based on the surface-active properties of the coal regarding an easy foaming; further the coal concentrate created during the foaming and the harsh ash fraction nearly freed from the coal and fine components are filtered in filters (7a), (7b) and at least a harsh ash fraction containing silicate and being nearly carbon free is transferred in order to evaporate the water left over during the filtering by using hot, low pressure work gas through a pneumatic classification device as dried to product silos (12) and (13) and the concentrated coal is returned to produce energy.