Stadler Ballistic Separator delivers in test landfill site excavation
The theoretical research on mechanical processing was tested in real conditions in the Mont-Saint-Guibert landfill in Belgium. The landfill waste was excavated and processed.
Ulrich Sigmund, Head of Research and Development at Stadler, describes the process: “An STT6000 Ballistic Separator was used in the first step of the mechanical treatment for the recovery of RDF and other recoverables, such as metals and inert materials. The machine separated the output in three fractions – fines, rolling fraction and flat fraction – which were then treated separately in order to investigate further recycling possibilities.”
Dr. Cristina Garcia Lopez, one of the New-Mine project´s researchers, adds: “Since the landfill waste is a very complex and heterogeneous material due to the amount of impurities, the ballistic separator provided us the opportunity of dosing the unsorted and unshredded excavated waste into three different material flows: potential RDF, 3D fraction and fines. It also allowed us to sort the landfill waste in its original size without shredding, avoiding the loss of small particles in the fine fraction – which required fewer steps. Besides, the great infeed of the ballistic STT 6000 (150t/h, depending on the density of the material), made it quite interesting since the amount of waste buried in landfills is considerably high while the general mechanical processing capacity is really low compared to the excavation capacity.”
Landfills present a particular challenge, as Dr. Lieven Machiels explains: “The level of moisture of landfilled waste is much higher than in fresh waste, and the waste is strongly degraded. Work package 1 analyzed how this material behaves in all steps of the mechanical separation process and what the properties are of the different output fractions. This research was new, and therefore its results are important for the future of landfill mining.”
Dr. mont. Bastian Küppers, also a researcher in the New-Mine project, adds: “The continuous mechanical treatment of the landfill is extremely challenging, as the high water content leads to blockages in the process chain and reduces the performance of plant and machinery. This is especially true for fine fractions.”
Another significant challenge in the project was the fact that the excavated waste had to be processed on site, so the Ballistic Separator had to be installed on a temporary concrete foundation in the landfill.
The Stadler Ballistic Separator has overcome all the challenges, showing that it can perform in these difficult conditions and confirming the feasibility of the project: “The high moisture value of the material was very challenging because the input was composed of pieces of rock and lumps of earth of up to 100 kg,” says Ulrich Sigmund.
Mr. Christian Nordmann, Deputy Head of Research and Development at Stadler, who worked actively on the tests in Belgium, explains: “The machine is very robust due to the two drives and central lubrication during operation. Also, the bearings are very well sealed, so the machine can operate outdoors. This enables the STT6000 to deal with the challenges found in the excavated landfill material, such as high moisture, dust and impact. In the tests we were able to model the material separation, including mass distributions and material parameters of the derived fractions.”
Dr. mont. Bastian Küppers adds: “Stadler’s Ballistic Separator has proven to be very robust and useful for loosening up, separating and thus preconditioning the material for treatment.”
“The tests showed that a new approach of starting a recycling process with a separation in three fractions is possible. This saves wear and energy compared to standard processes with a shredder/screen combination,” concludes Ulrich Sigmund.