Hydromechanical extraction

As Hydromechanical extraction is referred to in mining method, wherein the minerals , usually coal , by means of high pressure from the rock are dissolved out. The method is used in seams with inclined storage . In this process, the minerals extracted are hydraulically removed. The combination of hydromechanical extraction and hydraulic extraction is known as hydro-mining . A mine where the coal is extracted using this method is also called a hydro pit .

history

Since ancient times, people tried to placer gold and other minerals by water jet win . The first attempts to extract hard coal by means of a water jet were made in 1935 in the Soviet mining industry. In the German hard coal mining industry in 1957, attempts at hydromechanical extraction were carried out at the Consolidation colliery . The aim was to end the use of demolition hammers in the half-steep and steep storage and also to reduce costs. In 1962, a large-scale test for hydromechanical extraction was started at the Carl Funke colliery . This trial run ran for a period of five years. Further experiments took place between 1965 and 1968 at the Robert Müser colliery . In 1968 the experiment at the Carl Funke colliery was finished and the hydromechanical extraction was fully operational. From October of 1977, was on the bill Hansa the trial run was added to the hydro-mechanical extraction of the same from the end of November the year started on the bill Hansa officially operating as a hydraulic pit. After the closure of the Hansa hydro mine, no hydro mining was carried out in Germany. In the Soviet Union, hydromechanical extraction is still carried out at the Jubilejnaja hydro mine.

The extraction process

In order to be able to extract the hard coal hydromechanically, a water jet with a pressure of 80 to 100 bar is required. With this pressurized water jet, the coal is then extracted from the seam . The extraction process is particularly advantageous in pillar construction , as the pillar space does not have to be entered during extraction. The extraction takes place in three phases. First, a pillar with the water jet is so in Verhieb taken that a 1.5 to 2 meters high and 3 to 4 meters wide recess is dissolved out from the seam. Then the niche thus generated is with the water jet against the already broken previous pillars widened. However, in this phase of extraction, the coal is left standing in the hanging wall area and against the neighboring pillar. In the last phase of extraction, the remaining pier parts are removed until the hanging wall collapses. The pillar is secured where it is necessary by means of supporting structures . During extraction, the water jet produces up to 2500 liters of water per minute. The water and the coal form a mixture known as turbidity . The pulp is conveyed through special channels for partial processing underground . There the coal is partially recycled, concentrated and then hydraulically over days promoted . The degradation losses in this process are between 15 and 20 percent.

Equipment needed

The central device in this form of extraction is the water cannon. This should be as light as possible, be able to generate a beam with a sufficient range, and be easy to operate. In order to be able to convey away the sludge generated during extraction, trough or trapezoidal channels must be laid in such a way that the sludge can be conveyed away by gravity. The channels must be open at the top in order to receive the conveyed material. The channels must be open at the top so that the material can be conveyed by gravity. There is also the option of conveying the pulp via a pipeline. In addition, a system is required in which the coal can be processed for surface extraction. A roller crusher is required to crush larger lumps of coal. A collecting basin is required to thicken the slurry. The rinsing water must be reused so that the water consumption is not excessively high. Water treatment is required for this. The entire process is controlled and monitored from a central control point.

Application, advantages and disadvantages

The method can be used in partial bottom fracture construction and in chamber construction. Another mining method that is suitable for hydromechanical extraction is pier construction. The advantages of this procedure are first of all the improved occupational safety . Since the process does not generate dust through the use of water, the risk of silicosis is prevented. Since the actual mining area does not have to be entered, the risk of work accidents is also reduced. This is aided by the lack of rotating machines. Since there are no electrically powered machines in the seam area, the risk of ignition is greatly reduced. Only a small part of the exposed slope end area needs to be upgraded. In the case of thickness fluctuations and geological disturbances , the process is easier to handle than longwall mining . The disadvantage is that the method cannot be used for all types of storage. A general incursion of at least 20 gons is required. The method is also unsuitable for seams with water-soluble adjacent rock. The strength of the coal also places limits on the process. Tough and hard coal cannot be extracted economically hydromechanically. Depending on the mining method used, the introduction of backfill is not feasible.

Individual evidence

↑ ^a ^b ^c ^d ^e Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary . 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .
↑ Helmut Schaefer (Ed.): VDI-Lexikon Energietechnik . Springer-Verlag Berlin Heidelberg GmbH, Berlin Heidelberg 1994, ISBN 978-3-642-95749-9 , p. 546.
↑ ^a ^b ^c ^d ^e ^f ^g Horst Detering: From evening light to dwarf mother . 400 years of mining in Heisingen, 1st edition, Klartext Verlag, Essen 1998, ISBN 3-88474-739-8 , pp. 161–162.
↑ ^a ^b ^c ^d ^e Lars Bluma, Karl Pichol, Wolfhard Weber (eds.): Technology mediation and technology popularization . Historical and didactic perspectives, Waxmann Verlag GmbH, Münster 2004, ISBN 3-8309-1361-3 , pp. 73–83.
↑ ^a ^b ^c ^d ^e Ernst-Ulrich Reuther: Textbook of mining science. First volume, 12th edition, VGE Verlag GmbH, Essen 2010, ISBN 978-3-86797-076-1 , p. 471.
↑ ^a ^b Hydromechanical coal extraction and hydraulic extraction II . In: Commission of the European Communities (Ed.): Research books coal. No. 63, Gebirgsdruckforschung Synthesis Report I of the Steinkohlenbergbauverein, Luxembourg 1974, pp. 33–38, 84–89.

[Quelle_1-1] Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary . 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .

[Quelle_6-2] Helmut Schaefer (Ed.): VDI-Lexikon Energietechnik . Springer-Verlag Berlin Heidelberg GmbH, Berlin Heidelberg 1994, ISBN 978-3-642-95749-9 , p. 546.

[Quelle_2-3] ↑ ^a ^b ^c ^d ^e ^f ^g Horst Detering: From evening light to dwarf mother . 400 years of mining in Heisingen, 1st edition, Klartext Verlag, Essen 1998, ISBN 3-88474-739-8 , pp. 161–162.

[Quelle_3-4] Lars Bluma, Karl Pichol, Wolfhard Weber (eds.): Technology mediation and technology popularization . Historical and didactic perspectives, Waxmann Verlag GmbH, Münster 2004, ISBN 3-8309-1361-3 , pp. 73–83.

[Quelle_4-5] Ernst-Ulrich Reuther: Textbook of mining science. First volume, 12th edition, VGE Verlag GmbH, Essen 2010, ISBN 978-3-86797-076-1 , p. 471.

[Quelle_5-6] Hydromechanical coal extraction and hydraulic extraction II . In: Commission of the European Communities (Ed.): Research books coal. No. 63, Gebirgsdruckforschung Synthesis Report I of the Steinkohlenbergbauverein, Luxembourg 1974, pp. 33–38, 84–89.