Breakthrough in Sweden
Sweden is associated with Midsommar, elks and detective novels – and hard rock. A mobile plant combination from Kleemann is at work in the Boda quarry south of Stockholm.
With an average compressive strength of around 180 Mega-Pascals (MPa), granite is one of the hardest rocks on earth. The granite found in the Boda quarry near Vrigstad, a small town in southern Sweden, even yields values of more than 300 MPa in some cases. This imposes particularly high demands when it comes to processing the material. TJ Gräv AB, a provider of crushing services from Brandstorp, was contracted to process 40,000 tons of this material. The company was already familiar with Kleemann and its products and was quick to decide when new machines had to be purchased for the new order. “We bought our first crusher in 2007 after seeing the machines at work during a visit to Germany. In my opinion, they are durable and exceedingly robust,” says Tomas Johansson, proprietor of TJ Gräv AB.
Johansson chose a combination comprising a mobile jaw crusher and a mobile cone crusher with integrated triple-deck screening unit. The granite is first loaded onto the MOBICAT 120 Z jaw crusher with separate pre-screening unit by an excavator. The preliminary crusher reduces the original material with an edge length of up to 1,000 millimeters to a size of not more than 200 millimeters and then transfers it directly to the secondary crushing unit, a MOBICONE MCO 11 S. The mobile cone crusher produces three end products of different grain sizes in a single pass (see diagram on the right). This is achieved by the unit‘s three screening decks measuring 2,050 mm x 5,000 mm (middle and top deck) and 2,050 mm x 4,800 mm (bottom deck). A fairly large amount of material is in circulation due to the spreading the granite over three decks. As a result, the MCO 11 S cannot achieve its normal maximum total output of 280 t/h. Despite this, the mobile plant combination produces more than 1,000 tons of crushed stone aggregate per day.
Tomas Johansson considers the Kleemann plants to be particularly suitable for the job in Boda: “Both units have a diesel-electric drive, which is very good as regards the fuel consumption – in spite of the high load.” Other plant features are also important for Johansson. “Preliminary screening can be very important sometimes. In such cases, the end product must be virtually free from fine organic constituents, but that can only be achieved if the crusher has a separate preliminary screening unit.” For the provider of crushing services, it is essential that the units are easy to transport and that they are quickly operational after arriving at the new location. Mobile plants from Kleemann are ideal for such jobs.
ONE OPERATION, THREE END PRODUCTS
The MOBICAT MC 120 Z and MOBICONE MCO 11 S are electrically connected mobile crushers whose dieselelectric drives ensure particularly economical operation. The MOBICONE series of cone crushers is ideal for secondary crushing of hard rock, such as granite. Thanks to its triple-deck screening unit, the MOBICONE MCO 11 S operates in a closed material cycle producing three different grain sizes in a single pass.
|Operating site:||BODA Quarry in Vringstad, Sweden|
|Partner:||TJ Gräv AB|
|Machines on the job:||MC 120 Z and MCO 11 S|