Technologies from Kleemann and Benninghoven optimize recycling process.
At present, 12 million tonnes of RAP (Reclaimed Asphalt Pavement) are produced and used in Germany alone every single year — out of a total 40 million tonnes of paved material. It is a huge figure that highlights just how great the potential of recycling technologies is.
Systems and technologies from Kleemann and Benninghoven enable operators of asphalt mixing plants to boost their process efficiency. A particularly impressive example comes from the Juchem Group, a long-standing customer of the Wirtgen Group. The construction company have invested in four Kleemann Mobiscreen screening plants that screen the RAP, boosting the asphalt production quality and efficiency of the Benninghoven mixing plants.
New efficiency in the recycling process – With technologies from the Wirtgen Group.
For the Juchem Group, recycling reclaimed asphalt is part and parcel of their daily work. Layer after layer, Wirtgen cold milling machines of a variety of milling contractors remove damaged road pavements. This mono-material is transported to the group’s asphalt mixing plants for processing with equipment made by Kleemann and Benninghoven . The aim is to achieve aggregate fractions that are as homogeneous as possible, laying the basis for a high-quality end product. That is why the RAP needs to be screened thoroughly first. For the last few months, the Juchem Group have been deploying 4 mobile Mobiscreen MS 16 D and MS 16 Z screening plants from Kleemann for this process step. They are each operated in combination with a Benninghoven asphalt mixing plant of type BA at the Landau, Niederwörresbach, St. Wendel and Ürzig locations.
Step 1: Reclaiming and inspecting recycling material
In the rehabilitation projects carried out by the Juchem Group, Wirtgen cold milling machines remove the surface, binder and base courses, extracting three different fractions. It is not uncommon for 3,000t of RAP to be milled off in a construction project in just one work shift. “To ensure a high material quality, we inspect the RAP closely in our own laboratory and then select it,” says Dr Hermann Heppenheimer, Branch Manager at Asphaltmischwerk Landau Juchem KG. “The material also has to be highly homogeneous to allow further processing, and that calls for perfect processing techniques.”
Step 2: Screening with mobile screening plants from Kleemann
Next in line are Kleemann’s Mobiscreen mobile classifying screens. They ensure that up to 80% of the RAP can be used for direct further processing immediately after delivery. Only the oversize grain needs to be treated in crushers or a granulator. This method is a great deal more cost-effective than subjecting all of the RAP to secondary treatment.
Since part of the previously classified material is then stored in the open and can therefore become damp through exposure to the weather, fines < 5mm are screened beforehand, if necessary, and then stored in a dry place. This results in a significant reduction in the energy consumption of the asphalt mixing plant. The rule of thumb is that a 1% reduction in moisture corresponds to a 1 litre reduction in heating oil in 1t of asphalt mix.
These facts prompted the Juchem Group to buy 4 Kleemann Mobiscreen screening plants — three MS 16 D triple-deck screening units and one MS 16 Z double-deck screening unit. The MS 16 D used by Juchem has a throughput of 150 – 300t/h. The feed material (0- 150mm) is classified into the following grain sizes, depending on the asphalt formula of the mixing plant: 0-8, 0-11, 0-16, 0-22, or 0-32mm. The feed capacity is lower with finer screen meshes, but for the purposes of further processing, the focus is on achieving a homogeneous product. That’s another strength of Kleemann: the large number of different screen meshes combined with the simple replacement gives operators considerable flexibility. The operator can feed material to the MS 16 D while controlling it remotely at the same time. All the components of the unit are also easily accessible, making them very maintenance-friendly.
Step 3: Production of mix in the BENNINGHOVEN asphalt mixing plant
In the Juchem Group’s mixing plants, the classified RAP is processed into a new mix. This has been the case since 1999, when the company invested in one of the first parallel drum systems in the Rhineland-Palatinate region. “The investment in recycling feed systems from Benninghoven has boosted our competitiveness,” reports Dr Heppenheimer. Juchem have since equipped several of their asphalt mixing plants with a variety of systems.
Combination of multivariable feed and parallel drum systems delivers flexibility
The use of parallel drums, a hot feed system, is particularly worthwhile for large quantities and high RAP feed rates of up to 70%. Juchem also rely on the multivariable cold feed system. In this case, the RAP is fed directly into the mixer in a cycled process. Feed rates of up to 40% are possible. Why have Juchem integrated both systems into their recycling process? “It gives us the flexibility we need. The multivariable feed enables us to also cover small quantities from 2t. And we use the parallel drum for large jobs. Both systems are sophisticated and deliver first-class quality,” Dr Heppenheimer explains.
Kleemann GmbH is a member company of the Wirtgen Group, an expanding and international group of companies doing business in the construction equipment industry. This Group includes the five well-known brands, Wirtgen, Vögele, Hamm, Kleemann and Benninghoven with their headquarters in Germany and local production sites in Brazil, India and China. Worldwide customer support is provided by its 55 own sales and service companies.