Treatment of fly ash from coal combustion to improve its marketability

Abstract

A system and method for treating unmarketable fly ash and improve its properties as an additive for concrete is disclosed. The method includes the steps of providing a gas stream containing ionized air ( 34 ), and an amount of fly ash ( 10 ) containing carbon having an adsorption capacity. The fly ash ( 10 ) is then exposed to the gas stream ( 34 ) to expose the carbon to the ionized air to promote the attachment of the ions to the carbon to reduce the adsorption capacity of the carbon.

1 . A method for treating carbon-containing fly ash to reduce the adsorption capacity of the contained carbon, the method comprising:
 providing a gas stream containing ionized air;   providing an amount of fly ash containing carbon having an adsorption capacity;   exposing the fly ash to the gas stream to expose the carbon to the ionized air to reduce the adsorption capacity of the carbon.   
     
     
         2 . The method of  claim 1  wherein said ionized air is produced by exposing a stream of air to an alternating electrical field having a peak voltage of seven to twenty kV of peak voltage and a voltage rise and fall that exceeds 10 6  volts per second. 
     
     
         3 . The method of  claim 2  wherein said air has a high relative humidity, and said fly ash contains ammonia, so that the ammonia and water react with the fly ash to create an oxidizing species that further reduces the adsorption capacity of the carbon. 
     
     
         4 . The method of  claim 3 , wherein said gas stream containing ionized air is at a temperature below that required for oxidation of substantial amounts of the carbon. 
     
     
         5 . The method of  claim 4  and further comprising exposing the fly ash to ultraviolet light. 
     
     
         6 . The method of  claim 5  wherein said ultraviolet light comprises UV-C at 254 nm.