Patent ID: 8157431
Filing Date: 2012-04-17
Classification: E01C

Abstract:
1. A method of mixing HMA comprising the steps of: providing a rotary drum pre-heater configured to move RAP in a first direction and to preheat said RAP to a temperature approaching, but not more than the boiling point of water inside of said rotary pre-heater; directing such pre-heated RAP to a rotary shaft mixer; using said rotary shaft mixer for providing direct heating of said pre-heated RAP to a temperature of approximately 600 degrees F.; providing an oil heater to heat oil and to provide the heated oil to movable portions of said rotary shaft mixer, so as to heat such movable portions and thereby indirectly heat HMA disposed within rotary shaft mixer; providing exhaust from an oil heater to an open central counter-flow heated gas passage within the rotary pre-heater; providing steam from the rotary shaft mixer to a steam void in the rotary pre-heater; maintaining separation of the steam and the exhaust of the oil heater until such time as the water vapor has condensed from the steam to a liquid state; and regulating the temperature and the amount of exhaust and steam provided to the rotary drum pre-heater, so that the steam in the steam void does cool sufficiently to condense to a liquid before being exhausted separate from the air exiting the rotary pre-heater.