In the Garzweiler lignite surface mine operated by the RWE Power AG, the Lokotrack® LT1213STM, an impactor plant with screening equipment, does the job of up to three separate plants. According to first estimates, the deployment of the LT1213S in the Rheinische Baustoffwerke GmbH (RBS), a subsidiary of the RWE Power AG, has saved operating costs of about 30 %. “Depending on the desired product, we previously used to process the oversized gravel particles with up to three separate mobile plants – one jaw crusher, one cone crusher and one screening plant. According to the required end product, our new impact crusher LT1213S can do this job even alone”, explains Franz-Josef Santüns, Production Manager of the Rheinische Baustoffwerke GmbH. “In comparison to the fleet of three plants, the capacity increased from 100 t/h to 150 or 200 t/h – and this in a closed cycle.”
Lignite covered by sand and gravel
The Garzweiler surface mine, measuring 48 km2, is one of the three lignite opencast mines of the RWE Power AG in the Rhenish brown coal field. The lignite is covered, inter alia, by a thick overburden of sand and gravel which is selectively extracted by bucket wheel excavators within the framework of the overburden haulage.
Part of the excavated overburden, then in the form of gravel, is transported by band conveyors over several kilometers to reach a stacker that deposits the material in close proximity to the semi-mobile screening plant operated by RBS in the Garzweiler surface mine. The screening of sand with a grain size of 0 - 4 mm and gravel with 4 - 16 mm and 4 - 32 mm occurs in the screening plant; the oversize, up to 50 000 t/a, is crushed by the leased Lokotrack LT1213S, which is also used in other RBS gravel quarries for the crushing of oversize and coarse aggregate fractions. The end products of 0 - 45 mm, 0 - 32 mm and 0 - 16 mm as well as the aggregates and crushed sands which are produced in combination with a mobile screening plant are sold to local construction firms or further processed in the gravel washers of RBS.
“Significantly more efficient”
In January 2016, a technological shift from the previous mobile crushing to the Lokotrack LT1213S technology took place. First figures are already promising. “Our oversize processing has become significantly more efficient – at least by 30 %. We achieve considerable savings in fuel, as the impact crusher consumes only about 30 l/h. Precise figures will soon be available”, says Franz-Josef Santüns.
For this deployment, the LT1213S was equipped with composite cleats made of cast steel and with ceramic inserts from Metso, which, depending on the abrasiveness of the gravel, will bear up between 10 000 and 15 000 t. The impact crusher of the Lokotrack LT1213S runs at 430 rpm, the gap width is set at 16 to 25 mm. Due to the good quality, the end products are in great demand with local construction firms and used for a number of construction projects. “The new hydraulic gap adjustment is precise and particularly useful in the production of various end products. For the production of 0 - 16 mm, for example, we set the crusher gap to 16 mm and in a short time, the process runs smoothly again”, explains Franz-Josef Santüns.
“In Garzweiler, we are very satisfied with the service time and the availability of the machine. The LT1213S runs up to 8 - 10 hours per day, and if necessary, we can also produce in two shifts. The cleaning of the Lt1213S as well as the set back to transport position takes us only two hours, i.e. about half the time compared to the machines we used before”, adds Franz-Josef Santüns.