At the gravel pits owned by the North German family run company Lucht Sand und Kies, sand and gravel are now extracted under the management of the fifth generation. The current owner, Jens Lucht, and his father have long relied on mobile technology supplied by Extec for their operations. The decision for this came easy as the Extec S5 double screener with its two consecutively working screens – the pitch of each being adjustable to the material handled – obtained optimum screening performance in respect of capacity and the quality of the product grain. In spring 2011 another mobile screen, a Sandvik QA 340, was ordered from Oppermann & Fuss. This is an advanced model of the former Extec S5 screen (Fig. 1).
The QA 340 is equipped with a 7-m³-large feed bin, on top of which Jens Lucht ordered a double-deck vibrating grizzly as an optional extra, to obtain three efficiently sized products in one screen pass. The core component of the machine is, however, the unique double screen box with a total size of 5000 x 1500 mm. “No other screen of this size can screen to 2 mm as well as the QA 340,” says Jens Lucht. “Here we screen at hourly rates up to 350 t,” Lucht confirms when asked. In addition, he stresses the good cooperation with Oppermann & Fuss, the distribution and service company that took over representation of Sandvik screening and crushing equipment two years ago. “With this partner I can get all common spare parts on the same day or within 24 hours at the latest! If needed, a fitter is on site in the same time.”
To further improve cost efficiency in downstream production, a 24-m-long, wheel-mounted ST8042 stockpiling conveyor manufactured by Northern Irish manufacturer Anaconda was also ordered from Oppermann & Fuss (Fig. 2). This stockpiling belt is equipped with its own diesel power unit and can therefore be operated self-sufficiently. With a throw-off height of 10.30 m, the conveyor stockpiles 1600 m² sand. Stockpiling used to be done with a wheel loader, which can now carry out other tasks together with its operator.