Sealed former potash shaft site at Springen in the Rhön hills, where the Kaliseilbahn Springen–Dorndorf ropeway once carried salt to the Werra valley below.
The Werra-Kalibergbau Schacht Springen I, formally the Heiligenroda I shaft of the Gewerkschaft Heiligenroda, was the first of five potash shafts sunk by that concern in the hills above Springen in western Thüringen. Sinking began in 1908 and the shaft reached its final depth of 393 metres in November 1909 when the upper potash seam was intersected. The shaft lay about six kilometres from the nearest railway and was connected first, from 1910, by a 6,550-metre ropeway to the Kaliwerk Wintershall at Heringen, then from 1913 by the 3.5-kilometre Kaliseilbahn Springen–Dorndorf to the associated processing works at Dorndorf.
The processed salt product was potash and potassium sulphate. During the Second World War a sub-camp of Konzentrationslager Buchenwald operated at Springen, with prisoners forced to work in the mine. Potash production at all five Heiligenroda shafts ended in 1990 with the political transformation in East Germany.
The Kaliseilbahn was demontiert in 1990–1991. The shaft site today is sealed. The former Grube Springen void has been discussed as a future disposal site for production wastewaters from the still-active Hattorf-Wintershall mine complex.
The Gewerkschaft Heiligenroda was founded on 14 July 1906 and registered at the Saxon district court in Vacha on 21 October 1908. Its concession area, the Heiligenroda and Dönges fields together covering some 59,570,000 square metres, lay entirely in the Sachsen-Weimarische state, adjoining the concessions of Alexandershall, Wintershall, Heringen, Hattorf, Großherzog von Sachsen, and Kaiseroda. The ore deposit consisted of two nearly horizontal seams of mainly sylvinite and hard salt.
Schacht Heiligenroda I — designated in the TSV as Schacht Springen I — was the westernmost of the three Springen-area shafts. Sinking began in 1908. The shaft reached its final depth of 393 metres in November 1909, intersecting the upper potash seam. Rohsalzlieferungen for the Kali-Syndikat began in December 1909. The shaft wound raw salt by a drum winding machine driven by an electric motor of the Koepe-Scheibe type, as documented in contemporary technical publications.
Because the shaft lay approximately six kilometres from the nearest railway through the Werratal and in difficult hill terrain, the Gewerkschaft chose to connect it not by a dedicated branch line but by a Drahtseilbahn to the established Kaliwerk Wintershall at Heringen. This 6,550-metre ropeway, with a transport capacity of 45 tonnes per hour using 75 wagons of 600 kilograms each, was built within a few months; its acceptance inspection took place on 22 January 1910. The raw salt was ground in a dedicated mill at Wintershall and sold as Rohsalzgut, yielding a lower margin than refined product. Internal seilbahnen of approximately 1.5 kilometres linked Schacht I to the neighbouring Schächte II and III at Springen.
In 1912 and 1913 the Gewerkschaft Heiligenroda erected extensive processing works at Dorndorf in the Rhöngebirge. The Chlorkaliumfabrik entered service in August 1913 with a daily processing capacity of 20,000 Doppelzentner; the Sulfatfabrik followed in November 1913 with a capacity of some 800 Doppelzentner of 90-percent sulphate per working day. Also in 1913 the 3.5-kilometre Kaliseilbahn Springen–Dorndorf entered service, carrying potash salt from the Springen shaft complex across the Werra valley to the new Dorndorf processing plant and the rail despatch facilities there. Seilbahnen also connected the Schächte IV and V at Möllersgrund to the Springen complex. The two remaining shafts in the group, Heiligenroda IV and V, reached their final depths of 435 metres (July 1913) and 411 metres (May 1914) respectively.
The majority of the Kuxe in the Gewerkschaft Heiligenroda were held by the Wintershall-Konzern. During the First World War raw salt from Schacht I was processed at the Wintershall plant rather than at the Dorndorf works, to avoid the administrative and transport complexity of maintaining a separate factory for an externally supplied raw material.
During the Second World War a satellite camp (Außenlager) of KZ Buchenwald was established at Springen, and prisoners were compelled to work in the mine. A memorial stone in Springen today commemorates the victims of this forced labour.
After 1945 the thüringische portion of the Werra potash district was in the Soviet zone. From 1 September 1946 all potash operations in the Soviet zone were incorporated into the Sowjetische Aktiengesellschaft (SAG) for potash fertilisers. From 24 June 1952 they were transferred to Volkseigene Betriebe. Under the Kali-Syndikat consolidation of the 1920s the Gewerkschaft Heiligenroda had already passed into the Wintershall-Konzern sphere; in the GDR period the five Heiligenroda shafts at Springen and Möllersgrund were operated as components of the DDR potash industry. The Springen shafts delivered significant quantities of potassium salt for both domestic agricultural supply and hard-currency export.
With the political transformation at the end of 1989, potash mining in the thüringische part of the Werratal ended in 1990. The Kaliwerk Dorndorf, to which the Kaliseilbahn Springen–Dorndorf had transported salt since 1913, ceased processing on 30 June 1991; shortly after the operations at the Springen shafts ended, dismantling of the ropeway began, and it was fully removed by 1990–1991. The Kaliseilbahn Springen–Dorndorf was the last surviving ropeway in the Werra potash district when it was decommissioned.
The shaft tubes at Springen are now sealed. In December 2020 the Thüringen Landtag agreed in principle to amend the Kali-Staatsvertrag with Hessen to permit disposal of wastewaters from the still-active Hattorf-Wintershall mine complex into the void of the former Grube Springen. A public hearing of the Thüringen Landtag environment committee on this proposal took place on 19 May 2021.