Go with the Counterflow
Interview with Dirk Auler Product Trainer at BENNINGHOVEN
How can I add as much recycled asphalt as possible?
"The best way would be to split the old asphalt back into its original constituents. The old asphalt can then be reused in the mixing plant in accordance with the grading curve of the desired final product. We recommend using the “hot gas generator with counterflow parallel drum system” for this process. This makes it possible to achieve rates of 90% + X added recycled asphalt."
How exactly does this work?
"The recycled material is heated in a countercurrent. This means that the material flows towards the heat source in the drum. This allows higher material temperatures to be achieved while at the same time reducing the exhaust gas temperature. The outlet temperature of 160 °C corresponds to the further processing temperature, the exhaust gas temperature stands above the dew point, at approx. 100 °C. One positive effect for the white material is that the material no longer has to be overheated, which leads to a significant reduction in energy.
The entire process is only possible by using a hot gas generator, because direct firing would burn the recycled material and make it unusable. The burner, hot gas generator, drying drum, separating hood, and air circulation system are designed to work together perfectly."
How else can I conserve resources when mixing asphalt?
"In general, asphalt production materials should be stored in a dry place to protect stockpiles and feeder belts from the rain. When recycling reclaimed asphalt, moisture reduction is an issue that begins as early as the milling process. WIRTGEN milling machines cut water consumption by up to 20%, making the entire process more energy-efficient, because the following rule applies: 1% less water in the source material equals one liter less heating oil required per ton of asphalt during further processing into RAP in BENNINGHOVEN asphalt mixing plants."