Uhelná trasa
The Družba Open Pit
Modern economic development in North West Bohemia is based on the extraction and processing of brown coal. In the mid-20th century, dozens of underground and open pit mines were operating in the region of Sokolov. The underground mines were systematically closed down and operations turned to surface mining, which climaxed in 1983 with the production of up to 23 million tonnes of coal. The mining operations in the district encompass approximately 50 km2. The Družba Pit lies in the Sokolov Basin, which is vertically confined to the north and south by tectonic lines. The basin is filled with Tertiary sediments of fluvial, volcanic and limnic origins. The brown coal was formed in a swamp environment as the basin‘s depth decreased. It formed in two layers – the older seam of Josef was formed approximately 25 million years ago and the younger brown coal formations with the seams of Antonín (Anton) and Anežka (Agnes), 22 million years ago. The seam of Antonín, with an average thickness of 24 m, is mined in the open pit and lies approximately 200 m deep and rises towards the basin‘s edge. The seams are covered by grey claystone, which was deposited at the bottom of a Tertiary lake. Their lower section is mined for the production of the expanded ceramic granules “liapor”, and their top section contains layers used for reclamation purposes and sorbents, which are used in environmental protection. The basement of the seams, at the mine’s perimeter, contains exposed, coloured volcanic extrusions from Tertiary volcanoes. The unused overburden is deposited on an inner spoil heap in the open pit and on the outer Smolnice spoil heap.
