The Niederlausitz region is just under an hour's drive from Dresden on the A 13 highway heading towards Berlin. The area is a heath landscape characterized by its pine forests, which makes it hard to believe that this is one of Germany's largest lignite mining areas.
The diameter of the rotary
excavator wheels is 17 m
Exemplary recultivation measures have left large lakes, nature conservation areas and local vacation areas in the tracks of the gigantic coal excavation machines. These areas give the population a chance to go and relax whilst providing an environment for flora and fauna.
Opencast Mining
However, mining lignite in opencast mines does require the use of the heaviest machinery and the most modern technology. An opencast mine is a huge pit about 3 km long and 1 km wide. The coal lies at a depth of 40 to 100 m, so huge volumes of overburden have to be cleared away before the lignite fuel source can be reached.
This is achieved by using rotary and bucket excavators to dig out the pit to a depth of about
100 m over an area of 3 x 1 km. The overburden is collected by bucket and rotary excavators and transported by conveyor systems, overburden spreaders, etc. to the mined-out areas of the opencast mine where it is dumped. Some of the equipment in the overburden area is made up of conveyor bridges which run on rails, thereby enabling a strip of coal about 3 km in length to be uncovered. The coal lying in seams of 12 m thick is then dug out by rotary and bucket excavators and loaded into railway trucks via conveyor belts. The coal in the trucks is transported to power stations or coal conversion facilities.
Opencast mining operations on this scale make it necessary to lower the water table. This is achieved by installing well points in a zone dozens of kilometers around the mine, pumping out the ground water and channeling it away.
INTERBUS-ST modules provide
the interface between the
controller and the peripherals
Huge Scale
Looking into the mine gives a good overview of the complex arrangement of conveyor belts, excavators and the overburden bridge. INTERBUS links the numerous sensors, limit switches, contactors and motor protection switches on the conveyor belts via a serial cable and, in the case of conveyor systems for example, transmits the information either to the head station located several kilometers away or, for the large opencast mining machinery, to the control desk.
Harsh Operating Conditions
The opencast mine operates round the clock, come rain or shine. Every day, the mechanical and electronic systems of INTERBUS are subjected to vibration. In summer, it is not unusual for the installation to have to withstand temperatures in excess of 50 °C whereas winter brings ice, snow and temperatures below minus 20°C. By its successful use in this harsh mining environment, INTERBUS has now demonstrated that it is suitable for use in extremely exacting conveyor systems and environments. Although the INTERBUS cable runs past huge motors, these motors do not cause disruptions in the bus cable when they start up. The INTERBUS plug connectors make it easier to perform the frequent conversions which are necessary as the opencast mine moves onward, particularly in the case of the water drainage systems.
To summarize this, INTERBUS is being used in the Niederlausitz region to assist in opencast mining operations, thereby guaranteeing our supply of energy.
Dipl.-Ing. Bodo Seifert