Erzbergwerk Grund — Knesebeckschacht Bad Grund · Niedersachsen · Germany

The Knesebeckschacht is situated above the town centre of Bad Grund on the western edge of the Harz mountains. Mining in the Bad Grund area has a documented history extending back to the twelfth century; the Grube Hilfe Gottes, to which the Knesebeckschacht belonged, had its operational beginnings in 1831 when a state initiative resumed mining at the Todtemannberg by sinking the Hilfe-Gotteser-Schacht. The Knesebeckschacht itself was begun in 1855, initially as a Lichtloch — a ventilation opening — for the Ernst-August-Stollen, which was under construction from 21 July 1851. The adit was completed in 1864. As the workings extended in depth the Knesebeckschacht was gradually developed into a transport and man-riding shaft. To Beginn des 20. Jahrhunderts it had been expanded into a Fahr- und Materialschacht. It reached a maximum depth of approximately 499 metres. The man-riding function of the shaft was discontinued in 1974, after which it served exclusively as a ventilation shaft until the closure of the mine.

A landmark feature of the Knesebeckschacht site is the hydro-compressor tower, built in 1912. This 47-metre tower, probably the only surviving installation of its kind in the world, was constructed to generate compressed air for the underground machinery. Water from a mountain reservoir was carried by pipe to a specific point above the shaft and then allowed to fall vertically through the tower, dragging air with it and compressing it in the process. The compressed air was delivered to the underground workings via pipes. The compressor remained in service until 1977. The tower is designated a listed monument.

The broader Erzbergwerk Grund, of which the Grube Hilfe Gottes and the Knesebeckschacht formed the western part, was formed in 1923 when Preussag assumed control of all the state-owned mines in the western Harz and merged the Gruben der Berginspektion Grund into a single operation. The mine's main ore minerals were Bleiglanz (galena) and Zinkblende (sphalerite) with an average metal content of ten per cent, from which lead, zinc, copper and silver were extracted. The Achenbachschacht, completed as the modern main winding shaft of Grube Hilfe Gottes in 1907, replaced the old Hilfe-Gotteser-Schacht and from 1931 concentrated all ore winding. Further westward ore bodies were discovered in 1934 and 1950. The Westschacht was sunk in 1933 to provide ventilation for the western field. The Wiemannsbuchtschacht in the eastern field was sunk in 1951 and used for skip haulage of waste rock.

The closure of the Erzbergwerk Grund on 28 March 1992, the last metal ore mine operating in Germany, ended the Oberharzer Erzbergbau after more than 450 years. At closure about 200 miners lost their employment. Following closure, the mine machinery was removed and the water pumps were shut down; the workings below the level of the Ernst-August-Stollen flooded. In 2002 the Achenbachschacht was filled, closing the last access to the underground workings.

A mining museum at the Knesebeckschacht was opened in 1986, while the mine was still in operation. After closure, the museum was established more fully and presents the technical development of the site from the mid-nineteenth century to the end of operations. The surviving buildings, machinery and technical installations, underground vehicles, part of the Aufschlagröschen water management system, and the preserved hydro-compressor tower are all accessible. The site is part of the Welterbe-Route of the UNESCO World Heritage designation Bergwerk Rammelsberg, Altstadt von Goslar und Oberharzer Wasserwirtschaft, which was expanded in 2010 to include the Oberharzer Wasserwirtschaft. The surface installations at the Knesebeckschacht, the Wiemannsbuchtschacht and the Achenbachschacht are all preserved with their headframes standing.