The Brügmannschacht, founding shaft of the oldest still-accessible potash mine in the world, today serving as the visitor descent shaft of the Erlebnisbergwerk Glückauf at Sondershausen.
The Brügmannschacht (Schacht I) of the Kaliwerk Glückauf Sondershausen is the founding shaft of the eleventh German potash mine, located 4 kilometres northwest of the town between the villages of Stockhausen and Großfurra. Its sinking began on 1 May 1893 and it reached the rock salt horizon at 404.50 metres on 2 April 1895 and the hard salt seam at 634 metres on 9 September 1895. The shaft was named in honour of Heinrich Leonhard Brügmann, who initiated the project and died before production began.
Potash winding started in 1896 with 32,100 tonnes; from 24 February 1898, after the Chlorkaliumfabrik was completed, refined potassium chloride fertiliser was despatched. The Brügmannschacht and the Raudeschacht (Schacht IV) were the only two shafts kept partially in operation during the First World War. The underground workings of the Brügmannschacht reach the 670-metre level and extend to 1,150 metres where rock salt is still extracted.
Today the shaft serves as the visitor descent shaft of the Erlebnisbergwerk Glückauf, carrying visitors to the 670-metre level by cage.
The Brügmannschacht was the first shaft of the Kaliwerk Glückauf Sondershausen, founded by the entrepreneur Heinrich Leonhard Brügmann (1832–1893) from Brünninghausen bei Dortmund, who was both a trained mine surveyor (Markscheider), director of the Dortmunder Union-Brauerei, and a member of the Grubenvorstand of the Gewerkschaft Wilhelmshall zu Anderbeck. On 13 March 1891 Brügmann applied to the princely Landrat in Sondershausen for a Schürfschein; the licence was granted on 15 June 1891 and the first exploratory bore began at the Gänsespitze near Jecha on 1 August 1891. On 1 December 1891 rock salt was found at 465.2 metres depth, and six months later a 25-metre carnallite seam, the Kaliflöz Staßfurt, was intersected at 616 metres.
After prolonged negotiations with the Prussian state and its Schutzbohrgemeinschaft, a unique compromise was reached: Brügmann would be permitted to develop one works — the eleventh in Germany — but no further enterprises could be founded in the Fürstentum. He received the exclusive potash rights for 519 square kilometres. On 9 February 1893 Brügmann and the Cologne bank A. Schaaffhausenscher Bankverein founded the Gewerkschaft Glückauf-Sondershausen.
Sinking of the Brügmannschacht began on 1 May 1893, 4 kilometres northwest of Sondershausen between the villages of Stockhausen and Großfurra, close to the Erfurt-Nordhausen railway and on the bank of the Wipper. On 2 April 1895 the shaft reached rock salt at 404.50 metres; on 9 September 1895 it reached the hard salt seam at 634 metres, where a 14-metre potash seam of sylvite, halite, and anhydrite was intersected. Brügmann did not live to see production begin; he died of influenza in Cologne on 10 December 1893. The shaft was named the Brügmannschacht in his honour.
Potash production from Schacht I began in 1896 with an output of 32,100 tonnes, initially despatched unground. Following the completion of the Chlorkaliumfabrik, the first consignment of potassium chloride fertiliser left the Sondershausen works on 24 February 1898. On 1 March 1898 the Gewerkschaft became a full member of the Deutsches Kalisyndikat with provisional production quotas.
The Brügmannschacht was connected underground with the Petersenschacht (Schacht II) of the neighbouring daughter Gewerkschaft Glückauf-Bebra, which reached its hard salt layer at 760 metres depth in August 1910. During the First World War production was severely curtailed: Schächte I, III, V, and VI were temporarily closed, and only the Brügmannschacht and the Raudeschacht (Schacht IV) remained partially in operation.
From early 1922 the Wintershall-Konzern moved to acquire the entire Glückauf group, and on 20 September 1926 the Sondershäuser Gewerkenversammlung resolved on the liquidation of the independent Gewerkschaft. The Brügmannschacht continued as a production shaft throughout the DDR period when Sondershausen developed into the principal Kalikombinat of East Germany.
In 1989 the Brügmannschacht site produced its part of the mine's last-year output of 2,300,000 tonnes (2,299,400 tonnes according to one source). Potash production was discontinued in 1991 and from that year to 2002 voids under Sondershausen and Großfurra were backfilled to stabilise the old workings.
In 1995 the GSES GmbH was established as the privatised successor entity. The Erlebnisbergwerk Glückauf visitor mine was opened in 1998. The Brügmannschacht, sunk 1893–1895, continues to serve as the visitor descent shaft, lowering visitors to the 670-metre level from which they travel by small trucks to the old kali workings, reaching depths of up to 1,150 metres where rock salt is now extracted for road gritting at approximately 200,000 tonnes per year. A covered bridge to the cage was constructed in 2015 to handle increased visitor numbers.