Recycled asphalt process

A method of making hot mix asphalt using recycled asphalt, the method comprising:

• providing a hot air generator at a discharge end of a mixing chamber of a rotary counter-flow dryer;
• firing a burner into a refractory lined chamber of the hot air generator;
• producing products of combustion in the refractory lined chamber using fuel, primary, and secondary air;
• surrounding the refractory-lined chamber with an annulus;
• introducing tertiary air into the annulus;
• mixing the tertiary air with the products of combustion at an exit of the refractory-lined chamber to produce hot controlled temperature process air;
• increasing the temperature of the tertiary air while decreasing the temperature of the product of combustion to adjust a temperature of the hot controlled temperature process air;
• heating particles of the recycled asphalt by exposing the particles to the hot controlled temperature process air in the rotary counter-flow dryer and mixer and removing moisture from the recycled asphalt with the hot controlled temperature process air;
• adding virgin aggregates into the rotary counter-flow dryer as a fraction of the recycled asphalt;
• mixing the recycled asphalt and the virgin aggregates with liquid asphalt in the mixing chamber of the rotary counter-flow dryer;
• controlling the temperature of the hot controlled temperature process air to slow melting of bitumen in the recycled asphalt until it is mixed with the liquid asphalt;
• adding indirect heat to a mixing chamber of the rotary counter-flow dryer and mixer by introducing the hot controlled temperature process air into a rotating tube that radiates heat into the mixing chamber;
• maintaining a temperature of the hot controlled temperature process air introduced into the rotating tube and the rotary counter-flow dryer and mixer by modulating an amount of the tertiary air;
• measuring an exit gas temperature from the rotary counter-flow dryer and mixer and adjusting the burner in response to a moisture level of the recycled asphalt entering the rotary counter-flow dryer and mixer;
• adjusting the burner in response to the exit gas temperature;
• limiting a temperature of the rotating tube to the temperature of the hot controlled temperature process air;
• melting the bitumen in the mixing chamber without substantially coking the bitumen;
• and
• collecting and separating coarse and fine particles from an exhaust of the rotary counter-flow dryer in an inertial mechanical particle separator and adding the coarse and the fine particles to the recycled asphalt.