Carreau Rodolphe Pulversheim · Grand Est · France

The Bassin potassique d'Alsace extends over approximately 20,000 hectares across twelve communes north of Mulhouse. The deposit was discovered in 1904 by the master borer Joseph Vogt — who had been searching for oil — and his associates Amélie and Albert Zürcher and Jean-Baptiste Grisez, at Wittelsheim. Vogt assembled investors to exploit the find; the large German potash industry almost immediately acquired most of the concessions through a takeover, leaving Vogt with the concessions covering Ungersheim, Ensisheim, Pulversheim, and Battenheim covering 2,200 hectares. He founded the Kali Sainte-Thérèse (KST) company in 1910; his son Fernand became managing director. The decision to sink a shaft at Pulversheim was taken on 10 October 1910. Fonçage of puits Rodolphe no. 1 began in January 1911, interrupted at 89 metres and resumed in April 1912. The lower potash layer was reached at 694.25 metres on 1 August 1913 and the shaft was completed at 711 metres depth, with a diameter of 5 metres to 59 metres then narrowing to 4.50 metres. Concurrent with the fonçage, construction of the workers' cité Alex I began. The steel headframe — 40 metres high, of German type with load-bearing faux-carré, two superimposed molettes, and supported by two lattice-girder bigues — was built in 1911–1912 by the firm Zehne-Tscheiller. The extraction machine for puits Rodolphe no. 1 dates from 1912.

During the First World War, Fernand Vogt was arrested and deported by the German authorities. On 31 December 1915 a bomb dropped by a French aircraft destroyed an ammunition dump on the carreau, heavily damaging the surface installations, in particular the chevalement, rendering it temporarily unusable. After the Armistice of 11 November 1918, KST recovered its mines and undertook extensive repairs. The other potash mines in the region — the German-owned concessions — were placed under French sequestration and eventually acquired by the French state in 1924, becoming the Mines Domaniales de Potasse d'Alsace (MDPA) in 1935.

Joseph Vogt died in 1921 and was succeeded as president by Louis Mercier. In 1923 KST extracted 445,000 tonnes. Fernand Vogt was removed from the management of KST in 1923 and replaced by Félix Cussac. Fonçage of puits Rodolphe no. 2 began on 19 June 1925; it was completed in February 1928 at 744 metres depth, equipped with a large reinforced-concrete headframe built by the firm Zublin-Perrière. When puits no. 2 entered service, puits no. 1 became the ventilation shaft. The potash extracted was processed at the adjacent usine Alex. At this period a moulin à potasse (grinding mill) and a new underground changing room were also built.

During the German occupation and annexation of Alsace-Moselle from 1940 to 1945, the EKW (Elsässiche Kaliwerke) merged the MDPA and KST under a single entity. In the first month of occupation, on 23 July 1940, the worst accident in the history of the Alsace potash mines occurred at Rodolphe: a coup de mur followed by a grisou release killed 25 miners underground. It remains the most deadly accident in the history of the Alsace mines. A commemoration plaque at the entrance to the main building marks this event. At the Liberation in early 1945, KST recovered its mines, but by government decision the technical management of all Alsatian mines remained unified under the MDPA.

Post-war, the MDPA undertook extensive new construction at Rodolphe: hangars for heavy underground equipment, a day-shift stores, mechanical and electrical workshops, a carpentry, garages, and an administrative building. The lampisterie was converted into a combined changing room and canteen for day workers. By the peak year of the mine's activity, some 1,600 persons were employed at Rodolphe (900 underground, 700 at the surface). In 1959 KST leased all its mines, including Rodolphe, to the MDPA, transferring operations entirely. The MDPA had by this time integrated into the holding Entreprise Minière et Chimique (EMC) in 1967 and operated as Mines de Potasse d'Alsace. Basin-wide production peaked in 1974 at 13,361,000 tonnes of ore refined to produce 2.79 million tonnes of K₂O. Rodolphe, however, closed before this peak: extraction of the division Bollwiller — comprising mines Alex, Rodolphe, and Ungersheim — ceased on 9 July 1976 after approximately 39.5 to nearly 40 million tonnes had been raised from the Rodolphe complex. The last salt was offered to each miner in a commemorative flask.

Demolition of some elements — the changing room, the fabrication unit, and the bromine plant — began in 1980. Both puits Rodolphe no. 1 and no. 2 were backfilled in 1984. Demolitions ceased in 1987, when the site was acquired by the Écomusée d'Alsace and the Conseil général du Haut-Rhin. A rescue preserved the main production buildings, hangars, machinery, and both headframes. In 1994 the association Groupe Rodolphe was created, drawing on former MDPA miners, technicians, and engineers, with the initial goal of restoring the extraction machine of puits Rodolphe no. 1 (1912). The association constituted formally in 1997. In 2004 the faux-carré of puits Rodolphe no. 2 collapsed and was removed by cranes without damaging the main structure. The two extraction machines have been fully restored and are in working order. The site now holds two complete extraction complexes with chevalements and machines, a 1930 crystallisation hangar housing a collection of heavy underground machinery, two salt storage hangars built in 1929–1930, a water tower from the 1930s, and the monumental KST-style production buildings: moulin, bâtiment des mélanges, loading towers, and sack hangar. The machines inscribed by the Écomusée d'Alsace carry the label Musée de France. Since 2006 the carreau has been the property of the Conseil départemental du Haut-Rhin. Visits are guided by former miners of the Groupe Rodolphe association.