F. E. Schulte Strathaus GmbH u. Co. KG

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.

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
www.schulte-strathaus.de

Replacing scrapers on a conveyor belt system is almost always a lengthy process for any company. In the case of the Hohenlimburger Kalkwerke in Germany, the whole process took almost two years.

Ulrich Kolhagen is a mining engineer (Figure 1 ). After completing his studies, he started work in an ore mine and since 1989 he says, “I’m a quarry man”. He is operations manager at Hohenlimburger Kalkwerke, where Devonian hard limestone is quarried and treated. The plant is one of the few in Germany that washes its material, putting high demands on the conveyer belt system. Some 40 belts ensure that the broken limestone, stone chippings and frost proof gravel reach their transfer points. “Scraper replacement is almost always a lengthy process”, says Kolhagen. It took almost two years before all the equipment – with a few exceptions – was replaced with Starclean scrapers from the German manufacturer F. E. Schulte Strathaus GmbH & Co. KG, Werl, a member of FESS Group. As the operations manager explained, it was a gradual pro-cess. When a scraper reached the end of its service life, it was replaced by a new one. Eight were replaced in one go during the winter overhaul. Kolhagen: “It’s only feasible with rational planning. Production has to continue.”

The need for what the company described as “a considerable investment” were poor cleaning results. “There was too much carryback underneath and next to the belts”. Differing granulations and humidity of the material being transported put the scrapers under relatively high stress, particularly since quite a large amount of fine material demands fine scraping. Belt centre distances are between 7 and 220 m, with belt widths between 650 and 1,400 mm. Many aspects had to be taken into consideration during the refitting, according to the operations manager. The material from which Starclean scrapers are made – polyurethane for the primary scraper and a combination of polyurethane and carbide for the secondary scraper – is very important. Together with the right contact pressure, this guarantees consistently good cleaning results. The average service life of the blades is at least two years, after which they must be replaced.

“The investment has paid off for us”, says Kolhagen. The new scrapers have proven their worth, cleaning quality is good and fulfils expectations. Blades can be easily replaced without any tools and since their service life is relatively high, there is less work for the fitters. There has been an overall decrease in maintenance and servicing needs and the whole plant’s process reliability has increased. But the advantages cannot be measured solely in financial terms: “There have been improvements all round”, according to Kolhagen.

Further information/Weitere Informationen:
F. E. Schulte Strathaus GmbH & Co. KG
www.schulte-strathaus.de

“We want to be known as providers of integral solutions for conveying systems, not just as a scraper manufacturer”, says André Hanke (Figure 1), General Manager of the Starclean division of F. E. Schulte Strathaus GmbH & Co. KG (Fess Group), Werl/Germany. He is responsible for all conveyor system products and services. Before the company sold scrapers, tracking systems and impact beds, he explained. With the addition of an in-house developed transfer point seal to the product programme the company has now become a full-service supplier.

The Schulte Strathaus engineers examined similar solutions on the market before developing their new seal. The result is a transfer point seal previously not known to the market. Its unique design is based on the use of two different kinds of polyurethane. Hard polyurethane is used for guiding the material and softer polyurethane for the secondary dust seal. During conveying, the dust seal applies light pressure on the belt to prevent dust emissions. The relative softness of the material employed results in low wear on the belt and thus increased belt lifespan.

Another feature is that the seal can be adjusted when necessary. “That not only guarantees a further increase in lifespan, but also ensures a continually high level of dust emission prevention throughout its working life”, says Hanke. That in turn helps to increase efficiency and lower costs. Rubber would not have been a suitable material, according to Hanke, since rubber grinding against rubber would have produced too much friction and thus relatively rapid wear. The company also considered the use of polyurethane coated rubber impracticable: “As soon as the coating wore off, the seal would be useless”, Hanke says.

There is more competition within the sector now with Schulte Strathaus joining the ranks of full-service suppliers. “We can re-engineer complete conveying systems, including sheet metal work on the chutes”, added Hanke.

Further information/Weitere Informationen:
F. E. Schulte Strathaus GmbH & Co. KG
www.schulte-strathaus.de

The new two-piece STARCLEAN® SEAL transfer point seal of the F. E.. Schulte Strathaus GmbH & Co. KG eliminates material and dust emissions in belt conveyor transfer points and reduces maintenance and operation costs. At first, the material guiding primary seal keeps the bulk material inside the chute. The secondary dust seal, which is soft but abrasion resistant is adjustable in height and avoids dust emissions with smooth pressure. Enabled by a carefully chosen combination of special, multi component materials in different hardnesses the STARCLEAN® SEAL system reaches highest lifespans and optimum belt-saving properties. Optionally F. E. Schulte-Strathaus offers a toggle lever clamping set for installation and maintenance.

Further information:
www.schulte-strathaus.de