Patent ID: 11364481

Abstract:
A system and method for producing a modified coal ash involves collecting a bulk quantity of such coal ash, generally after it has been produced or landfilled, or is otherwise at temperatures closer to ambient, as opposed to power plant operational temperatures. In one possible implementation, the method herein involves removing carbon from the coal ash, such removal occurring by exposing the carbon to indirect heat, that is, externally-applied heat. For coal ashes with higher ash content. This removal is accomplished by subjecting the coal ash stream to heat, in one implementation, ranging between 850° F. and 1200° F., and such heat exposure occurring from about 10 minutes to about 30 minutes. The range of exposure time for the coal ash is determined so as to reduce the LOI from its initial level to a level acceptable for intended re-use or recycling. In one application, the LOI of carbon in the ash is reduced to 3% or less carbon. Upon completion of the range of the exposure time, the coal ash stream is removed from the sublimation heat, thereby forming a modified coal ash.