Method and apparatus for reducing carbon content in fly ash

Method of removing carbon particles from fly ash having a moisture content comprising the steps of:

• heating fly ash in a thermal processor to a temperature of at least 100.degree. F. to remove the moisture from the fly ash and break the surface bond between fly ash and carbon particles caused by moisture,
• applying the heated fly ash to the exposed upper surface of the belt of a generally horizontal belt-type conveyor in a thin layer,
• conveying said layer of heated fly ash by said belt below and overhead planar electrode of an electrostatic charging zone,
• repeatedly mechanically rearranging the orientation of the particles of fly ash in said layer while in said zone by increasing vibration to said layer by mechanical vibrations through said belt,
• subjecting said fly ash to an electrostatic field extending between the overhead electrode and said belt to impart on the carbon particles a charge in which the attraction to said electrode substantially exceeds the mass of such carbon particles for displacing said particles from said layer, and
• collecting said displaced particles in a bin.

Apparatus for separating carbon particles from fly ash, comprising:

• a generally horizontally-extending conveyor having a head pulley and a tail pulley, and having an electrically conductive conveyor belt extending between said pulleys, said belt defining an exposed upper conveyor surface along an upper run of said belt,
• a hopper for applying fly ash to be treated in a layer to said upper belt surface at a position adjacent said tail pulley,
• a portion of said conveyor downstream of said hopper defining a carbon separating zone,
• belt impact apparatus positioned adjacent a lower surface of the upper run of said belt in said zone for imparting vibrational excursions to said belt upper run in said zone for causing said fly ash layer to be in a state of agitation,
• an elongated electrostatic charging electrode positioned above said belt upper run and extending the length of said zone, and extending transversely throughout said zone a distance greater than the width of said belt with lateral edges of said electrode extending over said bins,
• said electrode having a surface spaced from said belt upper surface and transversely inclined to said belt upper surface,
• bins positioned along the lateral sides of said belt for capturing therein carbon particles discharged from said zone at such belt lateral sides,
• means for driving said belt so that said layer moves through said separating zone,
• means for applying an electrostatic potential difference between said belt and said electrode, and
• means at the off-running side of said head pulley for receiving ash from which carbon particles have been removed.

Apparatus for separating carbon particles from fly ash, comprising:

• a generally horizontally-extending conveyor having a head pulley and a tail pulley, and having an electrically conductive conveyor belt extending between said pulleys, said belt defining an exposed upper planar conveyor surface along an upper run of said belt,
• a hopper for applying fly ash to be treated in a layer to said upper belt surface at a position adjacent said tail pulley,
• a portion of said conveyor downstream of said hopper defining a carbon separating zone,
• a vibrator for causing said fly ash layer in said zone to be in a state of agitation for releasing carbon particles from said layer,
• an elongated electrostatic charging electrode positioned above said belt upper run and extending the length of said zone,
• said electrode being formed with two planar portions connected along a line positioned over the center of said belt and each diverging at a shallow angle from said belt planar surface,
• bins positioned along the lateral sides of said belt for capturing therein carbon particles discharged from said zone at such belt lateral sides,
• said electrode having a width which exceeds the width of said belt, with lateral edges extending over said bins,
• means for driving said belt so that said layer moves through said separating zone,
• means for applying an electrostatic potential difference between said belt and said electrode, and
• means at the off-running side of said head pulley for receiving ash from which carbon particles have been removed.