Patent ID: 8127931

Claim:
An apparatus for removing unburned carbon from fly ash, comprising a slurry adjusting tank in which a slurry is generated with the addition of water to fly ash, a collector addition device in which a collector is added to the above-mentioned slurry, a vertical high speed stirring tank in which the slurry with added collector is stirred at high speed and through the application of a shearing force and the collector is attached to the surface of the unburned carbon in the slurry, an adjusting tank in which a frother is added to the slurry having its surface modified by the high speed stirring tank, and a flotation unit in which the unburned carbon is floated and separated along with the air bubbles from the slurry after the frother has been added, wherein a plurality of the high speed stirring tanks are connected in series by connecting tubes and have a bypass channel arranged to bypass a predetermined high speed stirring tank connected by said connecting tubes.