Currently the Mitteldeutsche Baustoffe GmbH (MDB GmbH) with headquarters in Sennewitz near Halle is operating three quarries, 14 gravel works and two sand pits, in addition to several partnerships and two railway loading installations. With 180 employees and 20 trainees, the company is an important player in the building materials sector. They produce sands, gravels, antifreeze mixtures, screed gravels, backfills, various top soils, decorative gravels, erratic blocks, twice crushed and screened chippings, broken rock, mineral mixtures, hydraulic construction stones, stone mixtures and aggregates according to the specifications of the German Federal Railways as well as rock flour.
The Petersberg Quarry near Halle, which was industrially opened up in the 19th century, produces about 500 000 t of twice crushed and screened chippings, broken rock and hydraulic construction stones every year. Already in the twenties of the 18th century they started here to extract the characteristic reddish quartz porphyry here. During the extraction they also found a lot of interesting minerals, which still today are very much in demand among collectors.
For many years hydraulic excavators and rigid frame dump trucks have been the main equipment in the extraction chain. Together with the responsible division, Boris Mocek, the Works Manager of MDB, took a decision in favour of a première after successful presentations at the Steinexpo 2011, i.e. to use a front shovel excavator of the 86-t-class, type R800‑7A FS, from Hyundai Heavy Industries (Fig.). The key extraction unit was designed by the Hyundai dealer MGH Bautechnik Leipzig and was equipped with a front shovel of 4.5 m³ and was supplied in December 2011. The lined front shovel has been particularly designed for the rock pile making it possible to load the trough tipper with a capacity of 40 t in maximally six working cycles. Due to the LC carriage of 5940 mm in length, and equipped with twin-webbed track shoes, the excavator stands very quietly even with a wide working radius. This facilitates loading and increases the comfort for the driver. Furthermore, the wear on the carriage is minimized.
The CAPO system (Computer Aided Power Optimization) allows control of the hydraulic system at various performance stages according to the requirements. Thus, for example, more power can be directed to the operating equipment for quicker working movements. As regards the implementation, this means: 10 % more breakaway force at the touch of a button on the joystick. This pays off both during the loading operation and regarding the stability of the rugged unit of 86.5 t. Due to the air-conditioned cabin, the height of which was increased by 950 mm, the driver has a good view of the trough for optimum material distribution. During the loading breaks, blocks of stones are crushed by means of a drop ball with a weight of 1000 kg. The front shovel equipment consists of a basic boom of 4600 mm in length and an arm of 3500 mm in length. The diesel consumption of the Euro III-Engine (380 kW-Cummins QSX 15 turbo diesel) of the excavator also meets the requirements of the operator.
The unit runs eight hours per day and is used about 2000 hours per year. During the operating hours so far, the front shovel excavator has met the availability specifications of the operator.