Sealed shaft site of the Gewerkschaft Bernhardshall near Leimbach, now serving as an intake ventilation shaft for the active Erlebnisbergwerk Merkers of K+S Minerals and Agriculture GmbH.
Schacht Salzungen was the sole shaft of the Gewerkschaft Bernhardshall, sunk between 1896 and 1899 at a site west of Bad Salzungen near Leimbach. It was the first shaft to be completed in the entire Werra-Fulda-Kalirevier, though it failed to achieve commercial potash production. Sinking was halted at 332 metres, just short of the potash seam, because of severe carbon dioxide outbursts from the Rhön-volcanic salt.
Trials to establish whether a viable ore body existed continued until May 1901 but the workings proved uneconomic. Three miners were killed in carbon dioxide outbursts shortly after limited extraction began. The Kaligerechtsame passed to the newly formed Aktiengesellschaft Heldburg, which reopened the mine in 1903 and built a Chlorkaliumfabrik; however the same geological problems persisted and only rock salt was ultimately extracted for an associated Saline.
The works were finally closed in 1926. The Gewerkschaft Bernhardshall retained one field in which a carbon dioxide deposit had been found, and used this gas as feedstock for a Kohlensäurefabrik built near Leimbach on the Salzungen-Vacha railway. Schacht Salzungen today is connected underground to the Grubengebäude Merkers and serves as an intake ventilation shaft for K+S Minerals and Agriculture GmbH.
During 1943–44, archival holdings of the Preußische Staatsbibliothek zu Berlin were stored in the shaft workings.
The Gewerkschaft Bernhardshall was one of the earliest potash enterprises in the Werra valley, and the shaft it sank, Schacht Salzungen, was the first to be completed in the entire Werra-Fulda-Kalirevier. Teufarbeiten at Schacht Salzungen were conducted from 1896 to 1899 at a location immediately west of Bad Salzungen in the vicinity of Leimbach. The shaft reached a final depth of 332 metres but was halted just before intersecting the potash seam Hessen because of powerful carbon dioxide outbursts from the salt, a characteristic of the Rhön volcanic geology of the Werra region. Already during the trial borings in 1895 the Gewerkschaft Bernhardshall had encountered this feature of the Werra-Fulda deposit.
During the sinking, explosive carbon dioxide degassing occurred without causing immediate fatalities, but shortly after limited winding commenced, further carbon dioxide outbursts in the underground workings killed three miners. By May 1901 no viable potash occurrence could be established and the mine was closed on those grounds. The Kaligerechtsame of the Gewerkschaft Bernhardshall passed to the newly formed Aktiengesellschaft Heldburg. The Gewerkschaft itself retained ownership of a single field in which a carbon dioxide deposit had been discovered, and constructed a Kohlensäurefabrik (carbon dioxide factory) approximately 3 kilometres away near Leimbach, on the Bahnstrecke Salzungen-Vacha, to exploit this gas commercially.
In 1903 the Aktiengesellschaft Heldburg reopened the underground workings and commissioned a Chlorkaliumfabrik. The reopening proved only marginally better: the deposit remained uneconomic, in part because of the continued presence of carbon dioxide, and extraction shifted to rock salt for an associated Saline (brine works) which had been established on site. Potash extraction was definitively abandoned and only rock salt was produced. The works were finally closed in 1926. The Anschlussgleis (branch railway connection) to the mine was still partially visible in the landscape as of recent documentation.
During 1943–44 archival holdings of the Preußische Staatsbibliothek zu Berlin were evacuated to and stored in the stillgelegten Schachtanlagen at Bad Salzungen — which included the Bernhardshall site — for protection against Allied bombing. Following the end of the war these materials were removed.
Schacht Salzungen has since been connected underground to the Grubengebäude Merkers of the Kaliwerk Kaiseroda II/III and today serves as an einziehender Wetterschacht (intake ventilation shaft) for the active Grubenbetrieb Merkers, operated by the Werke Werra division of K+S Minerals and Agriculture GmbH.