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Fig. 1. One of the biggest mobile machines in the world: the AFB F60/34 conveyor bridge in the German opencast lignite mine Jänschwalde near Berlin. // Bild 1. Zählt zu den größten beweglichen Arbeitsmaschinen der Welt: die Förderbrücke AFB F60/34 im deutschen Braunkohlenrevier Jänschwalde bei Berlin. Photo/Foto: Schulte Strathaus

High belt speeds: a challenge for scrapers

High belt speeds represent a challenge for scrapers. Cleaning results are often less than satisfactory. But that is not always the case, as you can see at the opencast lignite mine in Jänschwalde, near Cottbus/Germany.

These are some of the biggest mobile machines in the world. They are approximately 200 m wide, 500 to 600 m long, up to 80 m high and weigh several thousand tons. We are talking about the four F 60 series conveyor bridges still operating in Germany, built by the former GDR company TAKRAF Lauchhammer. Their job is to transport and dump overburden from the mining area in the Lausitz lignite mines (Figure 1).

The maximum hourly load is a prodigious 34,000 m3. Once a year, “all bridges stop running”. The time is used for major maintenance and repair work. This time, primary and secondary belt scrapers also had to be renewed or replaced. Since the belts are not only hundreds of metres long and up to 3 m wide but also run at very high speeds of up to 10 m/s, the demand for cleaning efficiency, ease of servicing and durability are high. High speeds are extremely challenging for scrapers.

The main No. 5 conveyor belt alone reaches a speed of 9 m/s. Cleaning efficiency is often visibly reduced at such speeds and scraper wear and tear greatly increased. With the Starclean scrapers of F. E. Schulte Strathaus GmbH & Co. KG, Werl/Germany, another manufacturer was found who can supply the particular needs. Both cleaning efficiency and ease of servicing were considered exemplary in practice.

Fig. 2. Starclean primary scrapers made by German manufacturer Schulte Strathaus adjust to the amount of material being conveyed by deploying individual segments.
Bild 2. Durch den Einsatz von Einzelsegmenten passen sich die Starclean-Kopfabstreifer von Schulte Strathaus den jeweils geförderten Massenströmen an. Photo/Foto: Schulte Strathaus

As Franz Hering, in charge of distribution in East Germany for Schulte Strathaus, explained, thanks to the use of individual blades the scrapers automatically adapt to the conveyed material and the belt (Figure 2). The automatic torsion tensioning device ensures that the segments always operate with the correct tension. Manual adjustment is unnecessary. The same principle applies to the secondary belt scrapers. Here too the individual carbide segments with polyurethane snap-on feet adapt to the belt in optimal fashion. In addition, their position ensures belt cleaning with reduced wear. Installation and maintenance are relatively simple thanks to the snap-on system.

Further information:
F. E. Schulte Strathaus GmbH & Co. KG