In 1938, two mines in Sosnowiec were merged: Kazimierz Coal Mine (1884) and Juliusz Coal Mine (1914), creating the Kazimierz-Juliusz Coal Mine in Kazimierz Górniczy in Sosnowiec. In 1945 Dorota Coal Mine joined the complex. It was the last European mine where coal was extracted in a unique system. Due to the enormous deposit angle, a longwall shearer did not work there (as in other Polish coal mines). Explosives were placed in the mining walkway, and after the detonation, the crushed excavated material was placed on a belt conveyor. In May 2015, the last tonne of coal was mined, and the mine was decommissioned in 2019.