In open- cast lignite mining , conveyor bridges are used to transport and directly collapse the excavated material over the shortest possible route. They have supports on the mining side and the dump side of an open pit . Thus, they span the entire pit including other conveying equipment, for example that of coal mining.
On the mining side, they receive overburden from excavators, which they transport over the actual open pit mine on a conveyor belt and topple over on the pile side. This eliminates the need to transport the overburden with conveyor belts or trains around the open-cast mine, as well as tipping it down using a stacker . This also makes open-cast mining at deposits economical where a lot of overburden has to be removed in relation to the coal being extracted. Bucket chain excavators of the types Es 1120, Es 3150 and Es 3750 are currently connected to the overburden conveyor bridges.
Overburden conveyor bridges run on rail bogies in conjunction with the connected excavators parallel to the excavation edge. In order for the open pit to continue, it is necessary that the tracks are moved further in the direction of the excavation edge by special track- moving machines .
The world's first conveyor bridge, which was built according to plans by the Plessa mine director Friedrich von Delius , was put into operation in Plessa in 1924 . While conveyor bridges that were specially adapted to the respective opencast mines were initially built, in the 1950s the GDR switched to building overburden conveyor bridges of the same type as possible - the so-called standard conveyor bridges.
The largest overburden conveyor bridge in the world is the F60 . There are five bridges of this type in the Lusatian lignite district . Four of them are still in use today in the Nochten , Jänschwalde , Reichwalde and Welzow-Süd opencast mines . The fifth, now disused F60 is a visitor mine in Lichterfeld . It can be climbed by visitors, has a total length of around 500 meters, a height of 74 meters and weighs around 13,500 t. In combination with up to three bucket chain excavators, it is one of the largest land-moving machines in the world.
Other unit sizes were the F45 and F34. A total of two bridges of the F45 type were built, for the Meuro opencast mine and the Klettwitz opencast mine , while a total of 9 conveyor bridges were built of the F34 type. Almost all of these bridges have been moved from one open pit to another at least once. The last bridge of the type F34 (No. 27) was in use in the Cottbus Nord opencast mine until August 2015 and was blown up on March 3, 2016. Another conveyor bridge with a thickness of 34 m was located in the open- cast lignite mine Morosowskij (Ukraine). Like some others, it was dismantled as a reparation payment in Germany and rebuilt in the Soviet Union (e.g. Scado opencast mine , Ilse-Ost ). The sizes of the F60, F45 and F34 mainly differ in the intended removal height of 60, 45 or 34 meters. The real value depends on the connected excavators.
- Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum (ed.): The small mining encyclopedia. 7th edition, Verlag Glückauf GmbH, Essen, 1988, ISBN 3-7739-0501-7
- conveyor bridge F34 makes way for the Cottbuser Ostsee , Lausitzer Rundschau, March 3, 2016