Triangular construction
The triangular building is a mining method that exclusively in the shale mining has been applied. Since this method is only used in slate mining, it is not as well known as the other mining methods. The triangular structure was replaced by the transverse structure .
The dismantling process
In triangular construction, a distinction is made between two methods, the simple triangular construction and the triangular construction with hanging and lying pillars. The simple triangular construction is used for less thick slate deposits. These are slate beds with a maximum thickness of 26 feet and a dip in excess of 56 gons . Such slate stores are known as Leyen. These Leyen consist of a solid, closed mass, in which the hanging wall and the lying is almost continuously durable and firm. The triangular construction with hanging and lying pillars is used for deposits with great thickness and a fall greater than 56 gon.
Simple triangular construction
In order to mine the deposit with the simple triangular construction, a cross passage is first driven up to the deposit from a main line or a main tunnel. The warehouse is being dismantled by so-called walls, which have a trapezoidal profile . The height of the walls is between 12 and 20 feet. The short parallel side of the trapezoid is 2 to 4 feet long and lies alternately against the sole and the roof . The long side of the trapezoid is between 15 and 21 feet long. The sloped side is at an angle to the stroke line from 56 to 67 gons.
After three to four walls in the base have been dismantled, the dismantling under the base begins. This degradation takes place in a similar way. Depending on the water ingress, the so-called soils are mined to a depth of 12 to 15 feet. Afterwards, the resulting cavity is, with hereingewonnenem from the front bottom portion tailings , filled rearwardly. The roof is then dismantled with equal trapezoidal spaces 8 to 15 feet high. The resulting mountains are used for backfilling when the roof is removed. The offset is always introduced close to the roof. If you want to extend the bottom of the tunnel even further, a place remains open in the old man , for this the dismantling is started from the front area. If the site is not to be continued, mining is started from the rear of the deposit section.
This process continues until the deposit is depleted.
Triangular building with hanging and lying pillars
In principle, the process is carried out in the same way as the simple triangular construction. However, the parallel sides are designed with a sharper slope. In addition, pillars are left standing in the hanging wall as well as in the horizontal and partly in the middle to support the overburden. These pillars are dimensioned to withstand ridge pressure. In the case of shallowly falling deposits, however, they give way to pressure, as a result of which the outer layers of slate pull loose under the strong pressure and the roof collapses halfway up the pillar. To avoid this, additional support pillars are built. Since the pillars cannot withstand high side pressure, they are supported by a so-called arch when working on the ground or roof. This means that the slate must remain at a height of 6 to 16 feet across the camp. The pillars and arches will be partially recovered after the site has been completely dismantled and the widenings have been backfilled. However, most of these pillars and arches are lost and cannot be dismantled.
The usable roof slate
First of all, the roofing slate layers to be extracted are loosened by a process known as scraping. Here, one layer of roofing slate after the other is completely crushed with a special cutting machine. The depth of the shot depends on the thickness of the respective roof slate layers, it is 0.5 to 1 foot. If a deposit is criss-crossed by a fissure, no milling is done. The usable slates are then detached either by wedging them loose or by so-called gentle blasting with low-explosive explosives. The slate blocks obtained in this way are crushed into transportable slabs and transported above ground.
literature
- Carl Johann Bernhard Karsten, H. von Dechen: Archives for Mineralogy, Geognosy, Mining and Metallurgy. Eleventh volume, published by G. Reimer, Berlin 1838
Individual evidence
- ↑ Albert Serlo: Guide to mining science. First volume, published by Julius Springer, Berlin 1869
- ↑ Dunker: Overview of the usable mountain types, minerals and mineral springs. (PDF; 1.2 MB)