Pillar construction
The pillar method is a reduction method that the degradation of the plate-like deposits is applied. The process is particularly suitable for the degradation of powerful Steinkohlenflözen with little mountains funds for the mountain misalignment . In addition, this mining method is used for the mining of iron stone seams and for mining lignite seams . It is also suitable for mining rock salt deposits . This mining process, which is usually carried out by painting or floating, was used in coal mining for hydromechanical extraction .
Basics
Since the hanging wall is broken when building piers , it is also called broken pillar construction . Another name is pillar demolition . The reason for this designation is that the dismantling begins at the building boundary and is returned from there. The procedure requires a special route. The construction of the piers will be carried out in two separate sections, the driving of the routes and the dismantling of the piers. First of all, basic stretches starting from the shaft are driven to the field boundaries. These routes are usually driven as parallel routes . To ventilate the mining sites, the routes are connected by means of weather breaches. These weather blows also serve to control the strength of the piers. In the case of steep inclines, wide weather boreholes are created instead of the weather blows. Then the seam strips, which are located between two basic stretches, are divided into mining fields by floating companies. These mining fields are divided into pillars around ten to twenty meters wide. The pillars are then dismantled during dismantling, the upper pillars being dismantled first. The pillars can be dismantled either individually or in pairs. In contrast to on- site construction , the pillars are not left standing when building piers.
The miner differentiates between three types of pillar construction, depending on the location of the mining sections in relation to the seam level:
- Painting pillars
- Floating pillar construction
- Diagonal pillar construction
The striking length of the mining fields is between 100 and 300 meters. The length depends in particular on what difficulties it causes to keep the conveyor lines open. The flat height of the individual mining fields is determined by the formation of the bottom.
Painting pillars
The painting pillar construction is the most widely used mining method with piers, as it can be used at any angle . As a result, this method can also be used to manage gradual changes in the angle of fall relatively well. Therefore, this method can also be used in the area of hollows and saddles. In the second half of the 19th century, more than 50 percent of the funding in the Ruhr district was gained in the building of piers. First of all, the mining field is divided into pillars by several parallel mining stretches . With greater thickness , the pillars are seven to eight meters wide, with smaller thicknesses, pillar widths of up to 20 meters are selected. The width of the pillars depends primarily on the strength of the mineral to be mined. The width of the sections is chosen as large as the strength of the hanging wall allows. As a rule, the width of the routes is between two and two and a half meters. One of these floating stretches will be developed as a braking mountain , on which the extraction takes place from the mining stretches to the basic stretch. Are from the ropeway out sweeping pillars routes ascended at a distance of twelve to twenty meters. The dismantling of the pillars now takes place in floating or stroking strips or even over the entire width of the pillar. Dismantling takes place in the opposite direction to the drive-up direction, which is why one speaks of pillar demolition . To protect the tusks from falling stones from the hanging wall, safety measures are taken in the vicinity of the workplace by means of beams. In the area of the old man , precautionary measures are taken against the breakage of the previous pillars using special break stamps. As the mining progresses, these break stamps are stolen so that the old man can break.
Floating and diagonal pillar construction
With floating and diagonal pier construction, the excavation sections are driven diagonally or floating. However, the routes may have a gradient of a maximum of 4.4 gon . The pillars are then dismantled, sloping. Both mining methods can only be used in shallow seams. The dip may be up to 19.8 gon. Since both mining methods offer significantly more points of attack, they have advantages when stored flat compared to the pillar construction. This is especially the case if the deposit has a poor hanging wall. The use in seams with fire weather hazard is problematic , therefore these mining methods are not used here. These mining methods are almost unsuitable even if the seam has fallen heavily. Only in a few exceptional cases are these dismantling methods possible even with a larger incidence, here the use is possible with an incidence of up to 33 gon. The diagonal pillar construction was only used to a limited extent until the last third of the 19th century. Due to the great demands placed on the location of the deposit (flat storage), both methods were only marginally successful and were only used in a few marl mines in the northern Ruhr area.
Pillar construction in hard coal mining
The pillar construction can be used for thick coal seams without a large amount of mining, where the hanging wall is supposed to collapse . With this method, the mining of seams with a thickness of ten meters or more is feasible. In the case of deposits in which the hanging wall does not collapse quickly enough, in order not to leave the pier section open, the respective charred section is filled by means of an offset . In order to separate the filled section from the rest of the mining area, a wooden crate or a dam is placed in the appropriate places . In order to protect the other pillars and construction sections, an additional pillar (coal leg) is left here. With this mining method, the degradation losses are up to 40 percent.
Depending on its thickness, the seam is either mined all at once or, in the case of very thick seams, the seam is mined by strokes or, more rarely, by firs. When mining the entire thickness, the tusks have to be on the move in order to also mine the seam in the upper area. It can happen that lumps of coal injure the hammer working on the drive. The miner always has coal over him when the fires are mined, and the seam can break down in an uncontrolled manner when the upper banks are being won. For this reason, the quarrying is very dangerous and is rarely used. The safest method is the pus-like removal. First the upper bank is won and the roof is intercepted with caps and short stamps, so-called lost stamps. Then the middle bank is dismantled and finally the lower bank. The roof is supported with longer stamps. Pillars can only be used to a limited extent and with great effort in hard coal seams with little thickness. In order to get enough height, the sole has to be partially taken along, which in turn leads to a higher proportion of mountain climbing.
In the Lower Silesian coal mining , pillar construction was used in a modified form of striking quarry construction . From the beginning of the 19th century, the process was modified so that the old man was also filled with an offset . The process was improved several times and adapted to local conditions. This mining method then dominated Lower Silesian hard coal mining for 150 years and was only replaced by longwall mining after the First World War.
Seams with intermediate means
Thick seams with stone inclusions, so-called intermediate media, or several closely spaced seams with thin intermediate media are a specialty . Such special seams are being mined in two stages. First the lower seam is mined and then the upper seam. The intermediate means serves as a roof for the lower seam. The hanging wall is supported so that the upper seam does not collapse into the cavity after the lower seam has been excavated. This is done either by supporting them with joists made of punches and caps or by moving the cavities with excavated material . To avoid excessive tension in the intermediate means, the reduction is always carried out in sections.
Pillar construction in civil engineering
In civil lignite mining , broken piers are used when the lignite is not too hard. In lignite mining in particular, the great difficulty lies in the orderly breaking down of the hanging wall. Since lignite seams in the hanging wall can also have floating sand deposits in addition to clay , floating sand can be flooded into the fracture area when the pillars collapse. In the case of larger quantities, this floating sand emerges from the fracture area into the mining area. These floating sand deposits can make it impossible to dismantle it using broken piers. Here, dams are prepared in advance in the stretches in order to close them if necessary and thus to stop the inflow of swimming sand.
The excavation fields are divided up by means of intersecting routes. This creates square pillars around two to four meters in size. These pillars are then dismantled until the hanging wall collapses. Depending on the nature of the hanging wall, individual charcoal piers are left to support the hanging wall. As a result, mining losses amount to up to 50 percent in thick seams with soft coal and pressurized hanging walls. Since the mining areas are only ventilated through special ventilation or diffusion, the weather management is very difficult to design. Seams up to five meters thick are mined in one go. For larger widths to reduce such seams are several soles created. Very thick seams are mined in sections, so that a residual proportion of 0.5 - 1 meter of coal always remains. This coal strip serves as a hanging wall for the dismantling of the lower section. In seams with a thickness of 12 to 16 meters, the coal is extracted all at once in the chamber construction .
mechanization
While the piers were dismantled manually until the 19th century, mechanization came to the fore in the 20th century. Initially by means of drilling and blasting work, then later with special mining machines such as the continuous miner . In potash mining, the deposit is mined using continuous miners in the chamber pillar construction. If the hanging wall is poor, trackless conveyance is made more difficult. The reason for this is the expansion required when the hanging wall is poor . In the hard coal mining the pillar construction could not prevail, here the coal is extracted mechanically by means of longwall mining or local mining.
literature
- Emil Stöhr, Emil Treptow : Basics of mining science including processing. Spielhagen & Schurich publishing bookstore, Vienna 1892
Individual evidence
- ↑ a b c d e f Albert Serlo: Guide to mining science. First volume, fourth revised and up to the most recent edition supplemented, published by Julius Springer, Berlin 1884
- ^ A b Wilhelm Leo: Textbook of mining science. Printed and published by G Basse, Quedlinburg 1861
- ^ Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .
- ↑ a b c d e f F. Heise, F. Herbst: Textbook of mining science with special consideration of coal mining. First volume, published by Julius Springer, Berlin 1908
- ↑ a b c d e f g h i j k l m Carl Hellmut Fritzsche: Textbook of mining studies. Second volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1962
- ↑ a b c d e f g h i j k l m n o p Gustav Köhler: Textbook of mining science. 6th improved edition, published by Wilhelm Engelmann, Leipzig 1903
- ↑ a b c F. Freise: Alignment, installation and mining of hard coal deposits. Publishing house by Craz & Gerlach, Freiberg in Sachsen 1908
- ↑ a b c d Association for Mining Interests in the Upper Mining District Dortmund: The Development of the Lower Rhine-Westphalian Coal Mining in the Second Half of the 19th Century. Julius Springer's publishing bookstore, Berlin 1902
- ↑ Zygfryd Platek: Lower Silesian coal mining in the 19th and early 20th centuries ( Memento from October 22, 2007 in the Internet Archive )
- ↑ Self-propelled machine for the extraction of mineral raw materials, especially coal (last accessed on January 31, 2013)
Web links
- Patent: Procedure for pillar dismantling during chamber pillar construction and expansion unit for pillar dismantling (last accessed on January 31, 2013)