March 2, 2011
NCC Roads operates under the name “Ballast” some 90 plants across Sweden, some of which exporting to countries such as Poland, the Baltics and Russia. Ballast processes a total of 15 million tons of stone material per year.
At the Tagene pit in Gothenburg, 800 000 tons of red gneissic granite per year are turned into macadam used in concrete, asphalt, drainage layers when building houses, etc. The production flow reaches about 330 tons of crushed material in fraction 0-90 mm per hour.
In 2004, NCC Roads invested in a complete intermediary stage crushing plant consisting of a Sandvik CH660 cone crusher and a Sandvik CS86D screen, as well as several conveyor belts and feeders. The circular motion screen CS86D, of size 1,8 W x 4,8 L m, consists of 2 decks. The upper deck functions as a protection deck and the lower deck is separating at 63 mm. In its initial configuration, the screen was equipped with a crosswise tensioned rubber screening mesh, which did not prove to be optimal for the production. Indeed, due to the coarse fraction combined with the tonnage, certain areas of the screen mesh got heavily damaged and the life length of the material was way too short. Replacing cross tensioned screening media was heavy and would cause unnecessary production stoppage. NCC Roads needed a cost-effective and better solution.
Thomas Svedman, responsible for the sales of screening media and wear protection at SMC Sweden, initiated a discussion with NCC Roads’ production manager, Sten-Inge Persson, about the possibility to replace the rubber mesh with new and durable 45 mm thick modular rubber screening media from Sandvik.
The modules are not custom-made for specific screens, and they are adapted to fit most screens on the market. The solution is cost-effective, since only the worn out modules need to be replaced instead of, as in the past, the entire mesh. Furthermore, the modules can be moved around to maximize their life length. In addition, the costs are further decreased by the fact that only a few modules need to be kept in stock as opposed to an entire rubber mesh. The stable modules stay in place and optimize the flow of material. The system offers great flexibility when switching to another aperture size is required. Sandvik modular screening media is made of hard-wearing rubber material especially developed to give long life and minimal maintenance requirements.
In October 2007, both partners agreed to rebuild the existing Sandvik CS86D screen with modular rubber screening media. The installation was done during the winter close-down in January to minimize the impact on production. The operation took only four working days for the two decks, including operator training.
Sten-Inge Persson noticed very quickly the difference. The operators were pleased with the quick changes of screening media and the screen operated more smoothly.
„We can now easily move the modules around to get an even wear and thus maximize their usage. But what’s even more noteworthy is the fact that the screen operates much better now when the modules stay in place without fluttering, which the mesh did at the end of its life cycle. We are very pleased with both the costs savings and the improved operation obtained with the simple change to Sandvik modular rubber screening media,“ summarizes Stein-Inge Persson