Drying / Mixing

Double Barrel® X™ Dryer / Mixer

Double Barrel® X™ Dryer / Mixer

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The Double Barrel® X™ Dryer/Mixer for Hot Mix Asphalt Plants

The DBX dryer separates the drying process from the mixing process, thereby providing a very reliable plant to be used for the purpose of recycling reclaimed asphalt pavement (RAP). The concept allows for RAP to be pre-conditioned through the external part of the Double Barrel® X™ dryer, flashing off moisture in the drum, thus eliminating the problems associated with scavenger systems.

With a Double Barrel® X™ dryer the virgin aggregate passes through the inner drum and the RAP and baghouse fines are introduced into the outer drum where it is mixed with the already-heated virgin aggregate. As the RAP's AC softens, the baghouse fines evenly coat the RAP. The liquid AC is not added at this point. Instead, the aggregate, fines, and RAP mixture passes out of the Double Barrel® X™ dryer and moves into a mixing chamber (which can either be a pugmill or rotary mixer). This is where the liquid AC is added.

With the addition of the Green Pac™ option, the Double Barrel® X™ dryer produces warm mix asphalt.

Advantages of the DBX Dryer:

  • The plant can process asphalt mixes with up to 50% RAP content while maintaining zero opacity at the stack.
  • The liquid AC only enters at the mixing chamber, so virtually no build-up is produced in the dryer.
  • The hottest part of the drum is surrounded with the insulated mixing chamber, thereby providing the benefit of energy savings.
  • The producer has a choice of using either a rotary mixer (for large, abrasive aggregates) or a twin-shaft pugmill (which offers both compact size and efficient operation).
  • Virgin aggregate and RAP are discharged into a twin-shaft pugmill mixer/coater.
  • Choose a rotary mixer if working with large, abrasive aggregates.

A side elevation cutaway illustration of how the Astec double rap dryer mixer works