Turning RAP into black gold

Economical and environmentally friendly: the BENNINGHOVEN granulator MBRG 2000 turns RAP into a resource for new mix.

Recycling technologies are on the advance around the world. This is mainly because the earth‘s resources are finite – but it is also due to the associated reduction in costs. In road construction especially, the advantages are obvious: when roads are being rehabilitated and resurfaced, cold milling machines remove asphalt layers. And this raw material can well be regarded as “black gold”. And recycling technologies from BENNINGHOVEN make this possible – particularly the granulator MBRG 2000. The mobile plant breaks asphalt in blocks with an edge length of up to 1.8m down into its constituent parts without destroying the original grain structure. This careful crushing process ensures that almost 100% of the milled asphalt can be reused. Another great virtue of this crushing method is that it is associated with a much lower fines content. That means asphalt mixing plants from all manufacturers can process the granulated RAP without it sticking to the recycling drums and transport equipment.

Saving money while protecting the environment

RAP that has been crushed with the BENNINGHOVEN granulator can be almost entirely processed to form new mix. That is because the gentle crushing technique produces no additional fines. And that in turn allows the MBRG 2000 to achieve high recycling rates, benefiting both operators and the environment – cutting white mineral, energy and emissions in one fell swoop. Recycling rates in Europe currently stand at around 30% – and this figure is rising around the world. Depending on the market and statutory requirements, granulated RAP is being reused in all layers of the road paving right up to the surface course. The requirements on quality, the grading curve and the asphalt formulas are met in full; only the formulas are adapted accordingly.

Incidentally, asphalt mixing plant specialist BENNINGHOVEN also offer a large number of systems for the cold and hot feeding of RAP into the mixing process, allowing RAP proportions of 25 – 90 + X% to be achieved. You can find out more in the next issues of RoadNews or beforehand at www.benninghoven.com

Primary granulator

A wheel loader loads the hopper of the granulator. Inside, tampers carefully push the RAP or asphalt blocks onto a milling shaft located underneath. This prevents bridges from forming and brings about speedy and reliable crushing in the range 0 – 70mm. The easily exchangeable milling shaft is absolutely reliable thanks to wear protection and special cutters.

Screening unit and secondary granulator

The next stage of the journey through the granulator is the magnetic separator, where tramp iron is reliably separated. The pre-granulated material is then delivered onto an internal screening unit. Small grain sizes (0 – 8mm) are carried away directly by a stockpile conveyor. The fraction in the 8 – 22mm range, which already has the target size, is also transported away. The rest of the material goes into the variably adjustable secondary granulator, where it is crushed to grain sizes in a range ≤ 22mm. The crushing process is carried out by the shafts of the secondary granulator with hard cast lug shells. The oversize grain still contained in the material is returned to the screening unit. This ensures that the output is free from oversize grain.

Highlights of the BENNINGHOVEN granulator MBRG 2000:

  • Utilization of finite resources
  • Lower personnel costs
  • Minimal wear costs
  • Maximum cost-effectiveness
  • Minimal dust and noise emissions
  • Minimal fines content
  • Prevents blockage of the transport paths and the parallel drum to the greatest extent in the asphalt mixing plant
  • Can handle tramp iron
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