Patent ID: 6840712

Claim:
A method of thermal remediation of contaminated solid media, comprising: providing a vacuum housing equipped with at least one hollow shafted screw conveyor having a plurality of openings along its length, said vacuum housing providing two or more separate temperature zones along its length such that the temperature of each successive temperature zone can be maintained at a temperature which is equal to or greater than that of the previous temperature zone; indirectly and separately heating the two or more temperature zones to temperatures sufficient to volatilize one or more of the contaminants in the contaminated solid media; feeding the contaminated solid media into the at least one screw conveyor and conveying the contaminated solid media through the vacuum housing with mixing by rotating the at least one screw conveyor; injecting a hot, inert, non-condensible gas through the plurality of openings in the at least one screw conveyor to directly heat the contaminated solid media in each of the temperature zones to temperatures sufficient to volatilize one or more of the contaminants in the contaminated solid media; withdrawing the volatilized contaminants and the hot, inert, non-condensible gas from the at least one screw conveyor while holding the contaminated solid media under a vacuum; maintaining the vacuum on the contaminated solid media; separating the volatilized contaminants from the non-condensible gas; and discharging from the vacuum housing solid media reduced in contaminants.