Underground mining (soft rock)
As underground mining, the production of underground cavities (tunnels, tunnels, shafts, caverns, etc.) is referred to in the surrounding rock in closed design in mining and tunneling.
Underground mining, there were already in the Neolithic period. Archaeological finds from the 1984 date the flint mine of Abensberg - Arnhofen to 5500 BC From about 8 meters deep shafts flint was recovered by mining work. When a shaft was broken, a few meters further was a new geteuft and the old backfilled with the overburden of the new. This process represents the transition from open pit to underground mining
The tunnel construction is about 3000 years old, by means of fire setting has been degraded to the time of ore. Under Emperor Claudius a tunnel to drain the lake Fucino was driven about 2000 years ago. The first underground mines date back to the 16th century. So reached the pits of the Fugger near Kitzbühel a depth of 880 meters.
Development of the deposit
In underground mining, the differences lie in the orientation of the deposit. For development of the deposit by underground mining, there are two possibilities, the tunnel construction (including mining tunnels ) and cataloged the shafts. Critical to the type of development is mainly the depth and the shape of the surface.
A tunneling is applied in hilly terrain or in mountainous areas. For this purpose, and ascended to the horizontal, slightly inclined tunnel into the mountain located in the deposit and the deposit exploited. The tunnel construction is not suitable for reservoirs, which are located below the valley floor. Chance of scheduled reduction is operated below the lug sole by tunnel construction, in this case the conveyed via conveyor belts and the mine water has to be lifted by pumps.
For the development of the deposit via shafts first seigere or inclined shafts down into the reservoir or in the vicinity are sunk. Subsequently, the deposit is aligned with main lines and cross passages, then the degradation areas are pre- aligned. Finally, be dismantled and transported to further processing to days with a suitable mining method the mineral resources. The decomposition method based on the natural resource (raw material ), the deposit ( flözartig, gang -like or massive ) and the stability of the ground. Accordingly, there are special mining methods are used, for example, chamber construction, longwall mining, Weitungsbau, Teilsohlenbruchbau.
Depending on depth, a distinction has underground mining:
- Days near mining
- Near-surface mining
- Deep mining
As days near mining excavation work are referred to whose outer layer is less than 30 meters. In the days near the mining deposits were mostly accessed via tonnlägige shafts. For ventilation were similar to the tunneling mostly small shafts, so-called light holes sunk. A reduction method that has been applied in the days near mining to reduce irregular deposits occurring very often with low cardinality, was the Duckelbau.
As near-surface mining excavation work are designated with a top layer of at least 30 meters and a maximum depth of up to 100 meters. In the near-surface mining the deposits are developed both seigere and over tonnlägige shafts. In Braunkohlenflözen with widths up to 12 meters of Tummelbau has been applied very often.
Deep mining, often referred to as civil engineering, will take place in depths greater than 100 meters. In civil engineering, the deposits to be tapped in usually about seigere shafts, on some mines done the promotion of raw materials to feed mountains by strip mills. The mountains usually have an increase in 9-15 Gon and a length of several kilometers.
Underground mining often involves the installation of piles, and thus leads to a consumption of landscape. On the surface, it may cause large-scale subsidence and thereby come to mining subsidence. Underground mining can also cause the lowering of the water table and the pollution of surface waters. Another far greater danger arises when daily near and the near-surface mining. This can lead to the collapse of the overburden in inadequately secured underground cavities, which then leads to a day break. In the old, no longer used ( dropped ) shafts may occur Schachtverbruch with insufficient filling. Through this old, no longer used mines there is a risk of personal injury.