The Davidschacht waste rock pile was in operation from 1951 to 1964. It has a surface area of approx. 6.3 ha and a volume of approx. 760,000 m3. Due to the processing of ore from the Freiberg mining district at the Davidschacht, mainly residues from wet chemical flotation and finely ground components of the Freiberg gneiss were washed into the flushing dump.

The Davidschacht waste rock pile, together with the Hammerberg waste rock pile, the Grobbergedamm and the David-Richtschacht waste rock pile, is part of the former Davidschacht mining site. The Davidschacht waste rock pile is located on the north-eastern outskirts of Freiberg, directly on the valley slope to the Freiberger Mulde. Numerous commercial enterprises characterize the image of the Davidschacht site (IBUR, 1995b).

The beginning and the end of mining in the Davidschacht

With the construction of the David Shaft, work began in the early 1820s to excavate the old David discovery shafts. In the following decades, the cross-section of the shaft was extended several times. The Davidschacht was part of the former Himmelfahrt-Fundgrube ore mine, which has been documented since 1715 and was the largest mine in Saxony in the middle of the 19th century. After Himmelfahrt Fundgrube was taken over by the state in 1886, the mining equipment was modernized and the site further expanded. An ore washing pond was built in 1888. Like all mines in the Freiberg mining district, the Davidschacht was temporarily closed in 1913 (Fritze, 2000).

Mining was resumed in 1936, mainly for military reasons, and a new ore processing plant was built at the Davidschacht. This marked the beginning of the last operating period, which lasted from around 1937 to 1969 and in which the Davidschacht became the main production shaft of the Himmelfahrt mine alongside the Reiche mine. At 736 m, the Davidschacht is the deepest shaft in the Himmelfahrt mine area (Fritze, 2000). In addition to rope transportation, material transport and mining, the shaft was also used to mine ore for the entire Freiberg and Brand-Erbisdorf mining district from 1963 onwards. It was during this time that the huge slag heaps, which are still visible from afar today, were created. These were heaped up around the actual shaft site, where the winding shaft and surface mining and processing facilities were located. These are the David-Richtschacht coarse waste dump, the Davidschacht waste dump and the Hammerberg waste dump. The flushing dumps consist of the fine flushing sands and sludges from the processing plant, while the coarse mining dumps were filled with coarse tailings (TU Bergakademie Freiberg, 2016).

The Davidschacht slag heap was mainly in operation from 1951 to 1964. It comprises the old flushing basins of the first slag heap, which were constructed in 1943/44 and operated until they were exhausted in 1951, and the industrial tailings management facility (IAA) developed from it, the Davidschacht flushing slag heap (Fritze, 2000).

To seal off the valley, a dam was constructed to the east of the Davidschacht waste rock pile, consisting of coarse gravel material from the coarse gravel pile. The basal part of the western embankment consists of a pioneer embankment with coarse berm material, above which a berm of flushing sand was laid every four meters as the flushing progressed, so that in the final state three berms with a width of 3 – 4 m were created. Every year, around 50,000 m3 to 70,000 m3 of processing sands were injected into the Davidschacht waste rock pile. In 1969, the final closure took place with the end of Freiberg mining (Fritze, 2000).

After the end of mining in Davidschacht

After the end of mining, all mine workings below the Rothschönberger Stolln (230 m above sea level) in the Freiberg mining district were flooded. The former site with the above-ground facilities and buildings of the Davidschacht was assigned to the newly founded rationalization operation of the VEB Bergbau- und Hüttenkombinat “Albert Funk” Freiberg and the organization and computer center (1969 – 1989). The brick-built chimneys of the Davidschacht slag heap were backfilled and the protruding remains were blown up. In 1969/70, the flushing dump was covered with topsoil (Bergarchiv, 1958-1970). Since 1990, numerous exploration measures and planning services have been carried out at the Davidschacht site. The Davidschacht waste rock pile is currently unused.

Various BMBF research projects have taken place on/at the Davidschacht waste rock pile since 2012. Further projects are currently underway or being planned as part of recomine. The following is an excerpt:

• Project SMSB: “Extraction of strategic metals and minerals from Saxon mining tailings” as part of the funding measure “r³ -Innovative Technologies for Resource Efficiency – Strategic Metals and Minerals”, 2012 – 2016, project coordination: Helmholtz Institute Freiberg for Resource Technolog
• Project ReMining: “Plant for recovering valuable materials from sulphidic tailings and their environmentally friendly remediation” as part of the funding measure “r + impulse – impulses for industrial resource efficiency”, project coordination: GEOS Ingenieurgesellschaft mbH, 2017-2021
• ReMining Plus project: “Plant for the recovery of valuable materials from sulphide tailings and their environmentally friendly remediation” as part of the funding measure “recomine – resource-oriented environmental technologies for the 21st century”, project coordination: G.E.O.S. Ingenieurgesellschaft mbH; continuation of ReMining, 2020 – 2023
• SULTAN Project: “European training network for the remediation and reprocessing of waste deposits in the sulphide mining”, project coordination: Katholieke Universiteit Leuven, Belgium, 2018 – 2022
• EcoMetals-Project: “Innovative environmentally friendly processes for the extraction of strategic and rare metals from primary and secondary resources”, project coordination: Francoise Bodenan (Bureau de Recherches Géologiques et Minières), France, 2013 – 2017

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