Lutte

As Lutte also Lotte or air pipe, is referred to in the mining an airtight tube or an airtight box which for the ventilation of mines used. A special type of duct is the vortex duct , which is used to mix the weather.

use

Schematic representation of special ventilation with air duct

Lutten used to be used to transmit fresh weather from the weather machines to the mine workings. In doing so, these ducts went through the shaft for days and there to over the hanging bench . Special ventilation with a duct is necessary in mine workings that are not in the current of the weather (e.g. stretching or tunnel construction). The fresh weather is blown with a fan through the duct to the face . But air ducts are also used for gas extraction, for dust control, for air conditioning and for handling work after mine fires and mine accidents .

Types and materials

Wood, sheet metal or plastics are used as materials for ducts. The diameters of the ducts are very different. Until the middle of the 20th century, the duct diameters were between 200 and 800 millimeters, depending on requirements. Due to the increasingly longer routes with special ventilation, it is necessary to use ducts with an ever larger diameter. In the second half of the 20th century, the duct diameter was up to 1400 millimeters. In extreme cases, ducts with a diameter of 2400 millimeters are used today. These cords are several kilometers long.

Wooden chutes

Wooden ducts are made from boards or from pressed materials. They have a square cross-section with a clear width of 0.15 to 0.3 meters. Planed boards are used to manufacture wooden chutes made of boards. The ducts can be quickly made underground from boards nailed together. The joints of the boards are compacted. The ducts are laid so that they lie firmly and are not exposed to vibrations. Wooden ducts are connected either by a socket made from pieces of board or by being snapped on. With this type of connection, the boards on one side are sharpened and the boards on the other side are widened accordingly from the inside. This allows the ducts to be plugged into one another. Wooden pipes offer too much friction to the flow of weather. The angular cross-section creates a harmful space in the corners, which means that the cross-section of the duct is not optimally used. Another disadvantage is the short shelf life. Wooden pipes spoil quickly and have to be replaced very often. For dry stretches there were so-called light pipes. These were made from cardboard. In the event of damage, these ducts could be quickly patched with nailed-on rags. However, these light tubes were not resistant to moisture. Another construction method were wooden ducts made of weatherproof glued beech plywood. The surfaces of these ducts were molded with the aid of phenolic resin. The individual wooden panels are seven millimeters thick. Special connectors made of zinc sheet were attached to the ends, which made the duct connections tighter and prevented them from slipping apart. These ducts were lightweight, corrosion-resistant, resistant to mechanical stress and had a low pressure consumption. The pressure consumption of these ducts was even below that of sheet metal ducts. Damage to the wooden panels could be repaired with glued plywood patches.

Tin plumbing

Sheet metal ducts are made from iron or zinc sheet. The sheet thickness for narrow ducts up to 350 millimeters is between one and one and a half millimeters. Sheet metal thicknesses of up to two millimeters are used for wide ducts. Ducts made of sheet iron are more resistant than ducts made of zinc sheet. Cast iron ducts were also used in some mines, but this was discontinued for cost reasons. The ducts made of sheet iron are provided with a protective coating or a rustproof metal coating made of tin or copper. Due to the lower friction, sheet metal ducts can be provided with a smaller cross section than wooden ducts. In order to increase the resistance, ducts made of zinc sheet in particular are often made from corrugated iron . However, these ducts then again have greater friction. The resistance of corrugated sheet metal tubes is three to four times as high as the resistance of smooth sheet metal tubes. Sheet metal pipes are connected with socket connections, with band connections or with flange connections. With the outdated socket connection, the end of one duct is widened slightly conically and the end of the other duct is pulled together slightly. The joints are smeared with a putty mixture and then plugged into each other. However, these connections are not very tight, so that there is significant weather loss of 25 to 40 percent. With the tape connection, the ends to be connected are connected with a sheet iron tape. The sheet iron band is lined with canvas on the inside. The sheet iron band is tensioned using wedges, screws and levers. The band connection significantly reduces the weather losses compared to the socket connection, they amount to around 15 percent. The flange connection is the tightest and most durable connection. Sheet metal ducts are also laid in such a way that they lie firmly and are not exposed to vibrations. If sheet metal lines made of zinc are hung in iron hasps, wooden blocks must be placed underneath the contact points in order to avoid contact corrosion .

Flexible ducts

Flexible ducts can be swiveled along their entire length. They consist of thermoplastics with or without reinforcement. In some cases, sailcloth ducts were also used, but these ducts could not hold their own in German mining. The reasons for this were their flammability and unsuitability for wet operating points. In addition, they have to be sewn and quilted, which led to leaks. Another disadvantage is that they can only be used for blowing ventilation. For ducts made of plastic, PVC plastic films made of PVC plastisol are used. These ducts are flame retardant and have an antistatic finish. They consist of synthetic fiber fabrics coated on both sides with PVC plastisol. The ducts are tight, rot-proof and wear-resistant and, due to their flexibility, are insensitive to tears and other damage. Each duct consists of sections up to 100 meters long. There are hanging straps attached to the ducts for hanging. The individual pipe sections are equipped with coupling pieces at the ends. The sections are connected to one another via duct connectors in such a way that the coupling pieces are pressed tightly together. This means that no leaks can occur. There are also ducts that are held open by a spiral made of wire, these ducts are called spiral ducts. Spiral ducts can be used for both blowing and suction ventilation.

Individual evidence

↑ Explanatory dictionary of the technical terms and foreign words that occur in mining in metallurgy and in salt works and technical articulations that occur in salt works. Falkenberg'schen Buchhandlung publishing house, Burgsteinfurt 1869.
^ Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen, 1988, ISBN 3-7739-0501-7 .
^ Georg Agricola: Twelve books on mining and metallurgy. In commission VDI-Verlag GmbH, Berlin.
↑ Johann Heinrich Moritz Poppe: Encyclopedia of the Entire Mechanical Engineering, or complete instruction in practical mechanics and mechanical engineering. Fifth part, published by Georg Boß, Leipzig 1810.
↑ Ventilation of non-penetrable mine workings - special ventilation online (accessed on July 16, 2012).
↑ ^a ^b ^c Gerhard W. Becker, Dietrich Braun (ed.): Kunststoff-Handbuch. 2nd completely revised edition, Carl Hanser Verlag, Munich Vienna 1986, ISBN 3-446-14161-8 .
^ ^A ^b ^c ^d Carl Hellmut Fritzsche: Textbook of mining science. First volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1961.
↑ ^a ^b ^c ^d ^e Fritz Heise, Fritz Herbst: Textbook of mining science with special consideration of hard coal mining. First volume, fifth improved edition, published by Julius Springer, Berlin 1923.
^ ^A ^b Emil Stöhr, Emil Treptow: Basics of mining science including processing. Spielhagen & Schurich publishing house, Vienna 1892.
↑ ^a ^b ^c Albert Serlo: Guide to mining science. Second volume, 4th improved edition, published by Julius Springer, Berlin 1884.
^ ^A ^b ^c Emil Stöhr: Catechism of Mining Studies. Lehmann & Wentzel bookstore for technology and art, Vienna 1875.
↑ Academic dictionaries and encyclopedias Online (accessed July 16, 2012).
↑ Oldorid Kunststoffe GmbH: Duct connector for large diameters. Patent specification, DE file number 4117446 Online (accessed July 16, 2012).

[Quelle_12-1] Explanatory dictionary of the technical terms and foreign words that occur in mining in metallurgy and in salt works and technical articulations that occur in salt works. Falkenberg'schen Buchhandlung publishing house, Burgsteinfurt 1869.

[Quelle_1-2] Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen, 1988, ISBN 3-7739-0501-7 .

[Quelle_11-3] Georg Agricola: Twelve books on mining and metallurgy. In commission VDI-Verlag GmbH, Berlin.

[Quelle_9-4] Johann Heinrich Moritz Poppe: Encyclopedia of the Entire Mechanical Engineering, or complete instruction in practical mechanics and mechanical engineering. Fifth part, published by Georg Boß, Leipzig 1810.

[Quelle_10-5] Ventilation of non-penetrable mine workings - special ventilation online (accessed on July 16, 2012).

[Quelle_7-6] Gerhard W. Becker, Dietrich Braun (ed.): Kunststoff-Handbuch. 2nd completely revised edition, Carl Hanser Verlag, Munich Vienna 1986, ISBN 3-446-14161-8 .

[Quelle_2-7] A ^b ^c ^d Carl Hellmut Fritzsche: Textbook of mining science. First volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1961.

[Quelle_6-8] Fritz Heise, Fritz Herbst: Textbook of mining science with special consideration of hard coal mining. First volume, fifth improved edition, published by Julius Springer, Berlin 1923.

[Quelle_3-9] A ^b Emil Stöhr, Emil Treptow: Basics of mining science including processing. Spielhagen & Schurich publishing house, Vienna 1892.

[Quelle_4-10] Albert Serlo: Guide to mining science. Second volume, 4th improved edition, published by Julius Springer, Berlin 1884.

[Quelle_5-11] A ^b ^c Emil Stöhr: Catechism of Mining Studies. Lehmann & Wentzel bookstore for technology and art, Vienna 1875.

[Quelle_8-12] Academic dictionaries and encyclopedias Online (accessed July 16, 2012).

[Quelle_13-13] Oldorid Kunststoffe GmbH: Duct connector for large diameters. Patent specification, DE file number 4117446 Online (accessed July 16, 2012).