Active potash mine at Philippsthal (Werra), operating since 1908 as part of the K+S Verbundbergwerk Werra, with the Schacht Hattorf headframe and processing plant as the principal hoisting and production centre of one of the world's largest potash operati
The Schacht Hattorf, located at the Kaliwerk Hattorf in the Röhrigshof district of Philippsthal (Werra), Landkreis Hersfeld-Rotenburg in Hessen, is the main hoisting shaft of the Kaliwerk Hattorf and one of the two active shaft complexes at the Verbundbergwerk Werra, which is the largest potash extraction site of the K+S group and one of the largest in the world. Potash deposits at the site were identified in July 1897 when a borehole of the Kalibohrgesellschaft Hattorf struck the upper potash seam at 586 metres and the lower seam fifty metres deeper. Shaft-sinking began in September 1905 following the formation of a Gewerkschaft in 1905 and its conversion to an Aktiengesellschaft in 1906.
The first delivery of potash fertiliser from the mine was made in 1908. The mine expanded through the acquisition of adjacent field sections at Heimboldshausen and Ransbach, whose shafts entered service in 1913. Following the post-First World War crisis, production continued and the mine was acquired by the Vereinigte Kaliwerke Salzdethfurth AG from 1937.
On 1 July 1970, the mine was absorbed into the newly formed Kali und Salz GmbH, a BASF subsidiary created by the merger of Salzdetfurth AG, Wintershall's potash operations, and the Burbach-Kaliwerke AG. In 1979 an underground connection was established between the Hattorf and Wintershall workings, creating a combined field of approximately 150 square kilometres. The Verbundbergwerk Werra was formally constituted in 1997, integrating the Hattorf and Wintershall sites in Hessen with the Unterbreizbach and Merkers sites in Thüringen.
Schacht Hattorf remains an active main hoisting shaft. The cumulative output of the combined Hattorf-Wintershall field since 1903 reached one billion tonnes of raw salt in January 2024.
The first evidence of economically valuable potash deposits in the Philippsthal area came in July 1897, when a deep borehole of the Kalibohrgesellschaft Hattorf struck the upper potash seam (Werra-Formation, Zechstein) at 586 metres depth and the lower seam at approximately 636 metres. The commercially rich character of the find prompted a protracted period of fundraising. A Gewerkschaft was formed in 1905 to finance shaft construction, but the administration of share certificates became so disorderly that the organisation was reconstituted as an Aktiengesellschaft — the A.-G. Kaliwerke Hattorf — in 1906. Shaft-sinking began in September 1905; the first delivery of potash fertiliser (Düngesalz) was made in 1908, marking the effective start of production.
In 1909 the A.-G. Kaliwerke Hattorf promoted the founding of two further Gewerkschaften — the Gewerkschaft Heimboldshausen and the Gewerkschaft Ransbach — to develop the adjacent field sections. The Heimboldshausen shaft (final depth 803 metres, second shaft connected to the Ransbach shaft) entered service in 1913; the Ransbach shaft (final depth 810 metres, connected by underground breakthrough to Heimboldshausen) also entered service in 1913, having begun sinking before 17 December 1909. The Hattorf, Heimboldshausen, and Ransbach field sections thus formed a connected complex straddling the Werra valley.
The post-First World War collapse of the German potash export monopoly caused profound disruption across the Werra-Fulda Kalirevier. At Hattorf, the situation was complicated by the position of the mine immediately adjacent to what became the inner-German border: the transport railway through the Werra valley (the Bahnstrecke Gerstungen–Vacha) crossed the border twice, and its operation was periodically disrupted — requiring rerouting via the Hersfelder Kreisbahn between 1952 and 1954 and again between 1967 and 1969. Despite these difficulties, the Hattorf mine maintained production through the interwar period. From 1937 it belonged to the group of the Vereinigte Kaliwerke Salzdethfurth AG, which competed with the Wintershall AG for leadership of the German potash industry.
On 1 July 1970 the formal competitive era ended: both the Salzdetfurth group and the Wintershall AG's potash and salt operations were combined under the newly formed Kali und Salz GmbH, a subsidiary created under the umbrella of BASF. The Burbach-Kaliwerke AG, which had been a Wintershall majority holding since 1955, was included in the merger. In 1979 the Hattorf and Wintershall underground workings at Heringen were connected underground, enabling the transfer of raw salt between the two mines and shared ventilation — a technical and organisational milestone that created a combined field of approximately 150 square kilometres. The Verbundbergwerk Werra, combining the Hattorf and Wintershall sites in Hessen with the Unterbreizbach and Merkers sites in Thüringen, was formally constituted in 1997. In January 2024, the cumulative output of the Hattorf-Wintershall field since 1903 reached one billion tonnes of raw salt (Rohsalz).
The Schacht Hattorf is the main hoisting shaft of the Kaliwerk Hattorf and lies south of the Bundesstraße 62 together with the Aufbereitungsanlage (processing plant) and the Halde Hattorf spoil heap. The hoisting shaft and processing installation remain in active operation. The combined Verbundbergwerk Werra produces approximately 20 million tonnes of raw salt annually, from which around 3.5 million tonnes of finished products are made; it employs approximately 4,400 people.