At „Grube Clara“, located in the Rankach Valley in Oberwolfach, the industrial minerals baryte and fluorite are being mined underground.
For further preparation the material is being transported to the processing plant located 13 km away from the mine.
The annual production of crude ore amounts to 150.000 tons of baryte and fluorite.
From the produced crude ores various concentrates are produced.
Barite is used as a basic product in the automotive industry in sound reduction, underbody protection, plastics, carpets. Other applications are in the deep drilling, radiation protection and as heavy concrete example in counterweights for cranes.
Fluorspar is used in the chemical industry as a raw material of fluorine, which is part of toothpastes, refrigerants and much more applications. In addition, fluorite is used as a flux in the metal smelting, in welding electrodes or welding powders or in other melting processes.
The natural mineral deposits of Grube Clara consist of various veins which were formed by hydrothermal processes.
The baryte vein, known since the Middle Ages, is 600 metres long and has an average thickness of 3,4 metres. Meanwhile it has been mined up to depth of 800 metres. The fluorite vein lies parallel to the baryte vein and has an average thickness of 3 metres. The two veins are cut by a huge geological disruption and another vein called “Diagonaltrum” which is 2,5 metres thick and also contains baryte as well as fluorite. However it is workable in some small areas only.
There are two possibilities to get to the mineral deposit by truck: the Rankach adit and the main ramp that meanwhile has reached a length of a5 kilometers. The mining areas are accessible by so-called spiral ramps and crosscuts which meet the sublevels lying one upon the other every 12 metres. All drifts are excavated by drilling and rock blasting. For protection they are consolidated with anchors, plates and shotcrete.
The mining of the veins is also performed by drilling and blasting. The resulting voids are filled again with rock and binders.
The loaders topple the crude ore over into ore passes (small shafts). Trucks are being loaded from these shafts. They transport the crude ore directly to the processing plant in Wolfach where it is tilted on different stockpiles.
In the course of the dressing process the crude ore is being broken and washed, separated according to the specific weight, if necessary ground, floatated, dried and stored in different product silos from where the final products, mainly as flours, are being packed into big bags or loaded directly into silo trucks.