A process for reforming the fly ash by heating a raw fly ash powder that contains the unburned carbon and thereby decreasing the content of the unburned carbon, characterized in that (a) as means for heating the raw fly ash powder, use is made of a heating unit that heats the raw fly ash powder by passing it through a heated medium-fluidized bed, (b) a high-temperature gas stream is passed through the heating unit to form the heated medium-fluidized bed and to fluidize and convey the raw fly ash powder that is thrown into the medium-fluidized bed, (c) the flow rate of the high-temperature gas stream is so set that the raw fly ash powder thrown into the heating unit is all heated in the medium-fluidized bed and is taken out from a take-out port provided at an upper part of the heating unit but that the particulate medium forming the medium-fluidized bed is not discharged from the take-out port, (d) the fly ash powder after heated and discharged from the take-out port of the heating unit is introduced into an air classifier where it is separated into a fine powder and a coarse powder, (e) the fine powder separated by the air classifier is recovered as the reformed fly ash, and (f) the coarse powder separated by the air classifier is measured for its content of the unburned carbon and when the measured value is larger than a predetermined threshold value, the coarse powder is introduced again into the heating unit so as to be heated again and when the measured value is smaller than the threshold value, the powder is recovered as the reformed fly ash.

To provide a fractionating device capable of stably fractionating powders such as cement raw materials by a simple configuration. A fractionating device 1 for fractionating some of a powder (cement raw material) R falling in a chute (main body) 2, wherein the fractionating device is equipped with a screw conveyor 5 which passes through the chute, a part of a casing 5a opening inside the chute, and receives part of the powder from an opening (inlet) 5b, and a collision separation member (collision separation rod) 4 which is provided above the screw conveyor in the chute and collides with an object when an object of a predetermined size or larger falls, and prevents the object from falling directly onto the screw conveyor. A rotation shaft 5d of the screw conveyor may be inclined from 5 to 20 with respect to the horizontal plane so that the end of the discharge port side of the screw conveyor is positioned above the other end and may be equipped with a guide member 3 that guides the powder falling in the chute in the direction of the opening of the screw conveyor.

A process for reforming the fly ash by heating a raw fly ash powder that contains the unburned carbon and thereby decreasing the content of the unburned carbon, characterized in that (a) as means for heating the raw fly ash powder, use is made of a heating unit that heats the raw fly ash powder by passing it through a heated medium-fluidized bed, (b) a high-temperature gas stream is passed through the heating unit to form the heated medium-fluidized bed and to fluidize and convey the raw fly ash powder that is thrown into the medium-fluidized bed, (c) the flow rate of the high-temperature gas stream is so set that the raw fly ash powder thrown into the heating unit is all heated in the medium-fluidized bed and is taken out from a take-out port provided at an upper part of the heating unit but that the particulate medium forming the medium-fluidized bed is not discharged from the take-out port, (d) the fly ash powder after heated and discharged from the take-out port of the heating unit is introduced into an air classifier where it is separated into a fine powder and a coarse powder, (e) the fine powder separated by the air classifier is recovered as the reformed fly ash, and (f) the coarse powder separated by the air classifier is measured for its content of the unburned carbon and when the measured value is larger than a predetermined threshold value, the coarse powder is introduced again into the heating unit so as to be heated again and when the measured value is smaller than the threshold value, the powder is recovered as the reformed fly ash.