Ventilation

Chimney of a weather furnace to supply a mine with fresh weather ( Buchholz weather chimney )

As a term from mining, ventilation or pit ventilation stands in general for technical measures to supply mines with fresh air. Sufficient ventilation is required by law in the European Union for all underground workplaces.

history

Mine ventilation is about as old as underground mining . When the miners extracted minerals in underground mining and penetrated further and further into the mountains , the air circulating through natural diffusion in the mine workings was no longer sufficient. Very early on, the miners had to use tools and technical measures to avoid suffocating underground . In his twelve books on mining and metallurgy, Agricola describes how the miners used wooden constructions such as the weather hat to direct the wind into the mine or create an artificial weather draft with bellows . In the Harz mountain area, weather separators were used in the 16th century in order to achieve targeted weather management and thus to save light holes . The first weather machines were developed in the Harz mining area at the beginning of the 18th century.

tasks

Taking a closer look, three main tasks can be distinguished:

Supply of fresh air to the fresh weather
Removal of stale air and harmful gases
Lowering the temperature in warm pits

The supply of fresh weather is necessary to supply all people and animals underground with the air they need to breathe. In addition, there must be enough air for certain combustion processes, such as B. when operating the light , are supplied. This fresh weather must be distributed throughout the mine.

For discharging the used air the washing away or at least diluting the occurring underground belongs mats , toxic or beating weather. All of these gas mixtures then emerge from the mine again as weather . In many hard coal mines, vehicles with diesel engines have long been operated underground. The emissions from these engines must also be diluted or washed away by ventilation.

The air in the mine workings heats up due to different processes. The geothermal depth plays an essential role in warming the weather. But also through the compaction of the weather at great depths it comes to the warming of the weather. Here ventilation plays a major role in the air conditioning of the mine workings.

Generation of the weather movement

Natural weather patterns and their seasonal change of direction as a result of the temperature difference between the pit and the environment

In order to achieve a movement of the weather, one must either add some air to the amount of weather in the mine, i.e. blow it in, or remove some air, i.e. suck it off. Corresponding to this type of weather movement, one speaks of blowing or sucking ventilation. With blowing ventilation , the fresh weather is sucked in from the environment and pressed into the mine. The weather gets into the open through the pull-out shaft. With suction ventilation , the weather is sucked in from the mine and blown outside. At the pull-in shaft, the fresh weather falls into the mine, following the existing pressure gradient. The ventilation can arise through natural processes or be caused artificially. If there is a temperature difference between the mine and its surroundings and / or if there are different air pressures at the daytime openings , the air begins to flow through the mine, the stronger the greater the above-mentioned differences. Air pressure and temperature effects overlap so that they can complement or counteract each other. The influence of the temperature difference usually predominates. In this context, one speaks of natural weather patterns . In small, near-surface mines, the air currents created by natural drafts can be sufficient for a sufficient change in weather . The required strength of a weather flow depends on the number of people working underground, the number and performance of machines with internal combustion engines and the amount of harmful gases flowing in from the mountains. In most mines, the natural weather conditions are generally insufficient, so that the weather flow has to be generated with the help of technical measures.

Pit fan of a mine

A simple way to artificially strengthen the weather draft is to generate a heat lift by heating the downweather. This method was used with the fire bucket . The weather oven , which was first used at the beginning of the 18th century, was much more effective . It worked on the principle of suction ventilation. The convection of the fire burning in it created a current of air that accelerated the weather . Another way to create a weather movement is to use the natural wind. For this purpose, vestibules or weather hats are placed on the shaft , which should then direct the air currents on the surface of the earth into the mine. Bellows or weather wheels powered by human or animal power were also used. The facilities used for artificial ventilation are called weather machines . A distinction is made between weather-sucking and weather-blowing weather machines. Today, only pit ventilators (i.e. large fans ) are used as weather machines. These machines are usually set up as two-stage fans in order to provide the necessary pressure difference at great depths . Pit fans can have a nominal diameter of up to five meters with an electrical drive power of 2500 kW and are therefore among the largest fans built.

Weather management

The prerequisite for the supply and removal of air is that the mine has (at least) two underground openings to the surface of the earth ( day openings ): the air flows in through one, and out again through the other. Depending on how the weather flows through the mine , a distinction is made between ascending and descending ventilation. With ascending ventilation, the weather is guided by the shortest route to the deepest level. From there, they are directed upwards through the mine workings to be ventilated and then over the top level to the weather shaft. With sloping ventilation, the weather is directed from top to bottom through the mine building. As a rule, ascending ventilation is used in mining today.

Location of the weather shafts

Ventilation through the weather shafts

The location of the weather shaft is of particular importance for ventilation. Depending on the location of the weather shaft, a distinction is made between different types of ventilation. The weather shaft can be placed in the vicinity of the incoming shaft or on the border of the pit field . If you place the shaft near the incoming shaft, you will place it in the middle of the construction site. As a result of this positioning of the weather shaft, the weather initially flows from the entering weather shaft in the direction of the mine field boundary. After the mine workings have been ventilated, the waste air flow is now conducted to the middle of the mine field in order to be discharged from the weather shaft. The miner calls this type of ventilation central or retrograde weather management. If the weather shaft or shafts are set on the field boundaries, one speaks of borderline weather management. Here the weather moves from the middle of the field to the field boundaries and is discharged into the atmosphere via the weather shafts. Another possibility is to place the incoming shafts on the field boundaries and the weather shaft in the middle of the field. As a result, the outer working points are supplied with cool weather.

The retrograde weather pattern is best suited for the development of a new mine building. As soon as both shafts have reached the planned depth , a breakthrough is created between the two shafts. This is very important for the further alignment of the mine. A sufficiently strong weather stream is available for the alignment and installation work and one is not forced to wait for the breakthrough to a more distant manhole set on the field boundary. This type of weather management is also advantageous for dismantling near the shaft. However, as soon as the mine workings are a greater distance from the weather shaft and approach the field boundaries, the weather resistance increases with a simultaneous decrease in the width of the pit. Another disadvantage is the high risk of weather short circuits . With borderline weather management, the weather only has to cover the one-way route. Also, one always has the same long weather paths of medium length. In addition, with this form there is little risk of a short circuit in the weather. This type of weather management has a more uniform effect for the individual operating points. Here are simultaneously on the respective soles each crosscuts and basic routes better use of weather-technically. The borderline weather management is thus more reliable than the retrograde weather management.

Distribution of weather in the mine

Distribution of the weather:
a) The unaffected flow of weather leaves parts of the mine unpressurized.
b) By directing the flow of weather, all areas of the mine are supplied with air.

Without technical measures to distribute the weather in the mine, the weather flow between the pull-in and pull-out shaft would always move along the path with the least flow resistance. In the case of a very small and not very extensive mine building, it is often sufficient to ventilate the entire mine building one after the other with a single stream of weather. This is not feasible with larger mine buildings. The reason for this is that the weather routes are too long, and the cross-sections of the route would be too small to allow the entire amount of weather to flow through. In order to ensure the ventilation of the entire mine, the weather flow is divided into partial flows. For this purpose, the entire incoming weather flow is first divided into several main partial flows. These main streams are further divided into sub-streams. The division begins at the manhole that is drawn in, where the flow of weather is distributed to the individual floors. There, the individual main partial flows are divided into partial flows over the individual straightening sections and crosscuts . From there, the respective partial flows are further divided. Ultimately, this means that there are more than 60 partial flows in a mine building, depending on its size.

So that the weather supply also reaches those areas of a mine that are off this route, so-called weather structures are built in the mine . In principle, such a structure should increase the low flow resistance ( weather resistance ) in a mine construction to such an extent that the weather flow splits up and a certain part of the weather flows into a branching mine construction . Depending on how much the weather resistance has to be increased in one branch, this task places different demands on the construction of the weather structure. Simpler constructions are so-called weather screens . These are wooden frames built in transversely to the direction of flow or wooden frames covered with cloth, which influence the flow cross-section through more or less large openings and thus reduce or increase the weather resistance.

Weather door in the Bochum mining museum

If the rather complete separation of two weather routes is required, so-called weather locks are built. These are two largely airtight walls or walls that are erected a short distance apart. If the path is to remain usable for driving and material transport, doors ( weather doors ) are built into the walls . The double version is chosen, on the one hand, to increase the tightness and, on the other hand, if there is a large difference in air pressure between the two sides of the lock in order to be able to open the doors at all. For the sake of completeness, the so-called weather crosses should not go unmentioned in connection with the weather structures , the purpose of which is to separate crossing weather paths from one another.

However, any influence on the weather flow at one point changes the conditions in other branches of the weather network and increases the resistance of the overall system. This then leads to the fact that, under otherwise identical conditions, the overall weather flow ( volume flow ) passing through the mine is reduced. The disadvantage of a large number of partial flows is the increased effort for monitoring the weather management. Due to the strong branching of the weather, the weather speed of the individual partial streams also decreases . This ultimately leads to the weather warming up more. If air flows uncontrollably into areas that have been broken or filled after the mineral has been broken down ( old man ), this is known as a creeping flow . Creeping weather can be very dangerous, especially in coal mines, as they lead to spontaneous combustion of the remaining coal and can thus be the cause of a mine fire . After all of the mine workings have been ventilated, all of the partial streams reunite to form a single extract stream. This exhaust stream is weathered via the weather shaft.

Ventilation of the mining operations

In the past, when building the piers , ventilation was usually done through weather drill holes, hitting or chopping through. Starting from the basic route, the weather flow passes through all the throws one after the other and is ultimately discharged via the weather route. However, this method has the disadvantage that the weather, both in narrow and in wide pits, is enriched with mine gases. In narrow pits with widely branched weather paths, the performance of the suction fan is severely impaired due to the multiple curvatures of the weather paths. In the case of large pits, the curvatures have no effect on the performance of the fan. Today there are a total of six different forms of ventilation, depending on the type of mining, which are used depending on the layout of the deposit. These are the U, Z, Y, H, W and double Z ventilation.

With underground ventilation, the fresh weather sweeps in through one of the mining sections , from there through the longwall and then out again in the same direction through the other mining section. The direction of the fresh weather is either with or against the mining direction . In the case of Z-weathering, this is similar, only that the downweather takes an opposite direction than the fresh weather. With Y-ventilation, one section of the mining section is supplied with fresh weather, while the other is refreshed using fresh weather. The weathers leave in the opposite direction, either in the mining direction or against the mining direction, depending on the cut. With W-ventilation and with double Z-ventilation, the fresh weather is supplied over a middle distance. The weather is discharged via the two outer stretches, namely with W-ventilation against the mining direction and with double Z-ventilation with the mining direction.

Special ventilation

Special ventilation of non-penetrable mine structures:
a) blowing, b) sucking.

Pit workings in the driveway must, because they are not yet penetrable , i. H. are only open on one side, can be weathered in a different way. One way of weathering a route that is not penetrable is to divide the route into two parallel routes using a weather divider. The routes are only connected on site. In another method, following the construction progress, a weather duct is carried along, which is connected to a fan near the entrance. The technical terminology used in mining uses the term special ventilation in this context . In addition, a Sonderbewetterung be generated by air removal from the compressed air network, but this method requires the permission of the Mining Office . When setting up facilities for special ventilation, particular care must be taken that the waste weather is not mixed with the fresh weather flow and fed back to the area with special ventilation. In underground mining operations where mine gases occur, no special ventilation may be used. To mix the methane gas concentration with the weather stream, vortex tubes are used, especially in mechanical propulsion .

Special ventilation can be operated with blowing or suction:

In the case of blowing special ventilation, the fan sucks in fresh air from the fresh weather stream and blows it into the mine; the downpours flow back to the entrance outside the duct.
In the case of suction special ventilation, the fan sucks the waste air out of the tunnel and blows it out at the entrance; Fresh weather streams in from the entrance outside the Lutte.

Which form of special ventilation is used depends on what the purpose of the special ventilation is. Blowing ventilation has the advantage that the fresh weather is blown out on site. This has the consequence that the climatic conditions on site improve. The disadvantage is that the on-site team is adversely affected by dust turbulence or drafts. Another disadvantage arises when shooting when the crew is changing shifts. Although the explosive gases are flushed away on site by the blowing ventilation, this waste weather in the open cross-section of the route takes considerably longer to be flushed away. Suction ventilation has the advantage that it can quickly evacuate it, especially in the case of strong outgassing. However, the fresh weather only flows in at a slow weather speed, so that they may warm up or otherwise deteriorate on the way to the site. Another disadvantage is that the suction effect is only effective in the immediate vicinity of the end of the duct. As a result, firedamp can remain almost immobile on the face. This disadvantage can be avoided by using a small blowing duct with an economy fan, which then supports the ventilation on the face.

Individual evidence

↑ ^a ^b ^c ^d ^e Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. Glückauf Verlag, Essen 1988, ISBN 3-7739-0501-7 .

^ Wilhelm Hermann, Gertrude Hermann: The old collieries on the Ruhr. 4th edition. Verlag Karl Robert Langewiesche, successor to Hans Köster KG, Königstein i. Taunus 1994, ISBN 3-7845-6992-7 .

↑ ^a ^b Mining Ordinance for all mining areas (General Federal Mining Ordinance-ABBBergV) Online (accessed on July 17, 2012; PDF; 145 kB).

↑ The history of mine ventilation. Retrieved June 23, 2020 (43 pages, online at docplayer.org).

^ Georg Agricola: Twelve books on mining and metallurgy. In: Commission VDI-Verlag GmbH, Berlin.

↑ Wilfried Ließmann: Historical mining in the Harz. 3. Edition. Springer Verlag, Berlin and Heidelberg 2010, ISBN 978-3-540-31327-4 .

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Fritz Heise, Fritz Herbst: Textbook of mining studies with a special focus on hard coal mining. First volume, fifth improved edition. Published by Julius Springer, Berlin 1923.

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r Carl Hellmut Fritzsche: Textbook of mining studies. First volume, 10th edition. Springer Verlag, Berlin / Göttingen / Heidelberg 1961.

↑ Friedrich Prinz, Edwarda Forster, Dirk Dahmann: Determination of the pollution of the mine weather by diesel engine emissions in hard coal mines underground. Reprint from the magazine “Hazardous Substances-Reinhaltung der Luft” Volume 58/1998 Online (accessed on July 18, 2012; PDF; 43 kB).

↑ Ventilation of penetrable mine workings - main ventilation (accessed on July 17, 2012).

↑ Carl Hartmann: Conversations-Lexicon of mining, metallurgy & salt works and their auxiliary sciences. Second volume, J. Scheible bookstore, Stuttgart 1840.

^ ^A ^b ^c ^d ^e ^f ^g 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 revised edition. Published by Julius Springer, Berlin 1884.

^ Wilhelm Leo: Textbook of mining science. Printed and published by G Basse, Quedlinburg 1861.

↑ Fritz Heise, Fritz Herbst: Textbook of mining science with special consideration of hard coal mining. First volume, published by Julius Springer, Berlin 1908.

^ ^A ^b Emil Stöhr: Catechism of Mining Studies. Lehmann & Wentzel bookstore for technology and art, Vienna 1875.

↑ Reinhard Wesely: The development of weather technology and explosion protection in the early 20th century up to the mine accident at the Anna II hard coal mine in Alsdorf on October 21, 1930 . In: Anna . No. November 23 , 2005 ( online ( memento of July 26, 2015 in the Internet Archive ) [PDF; accessed June 23, 2020]). The development of weather technology and explosion protection in the early 20th century up to the mine accident at the Anna II hard coal mine in Alsdorf on October 21, 1930 ( Memento of the original from July 26, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2
^ Gustav Köhler: Textbook of mining science. Second improved edition. Published by Wilhelm Engelmann, Leipzig 1887.
↑ Heinz Kundel: coal mining . 6th edition. Glückauf Verlag, Essen, 1983, ISBN 3-7739-0389-8 .
↑ ^a ^b ^c ventilation of non-penetrable mine workings. (accessed on July 17, 2012)
↑ General mining ordinance on underground operations, opencast mines and salt pans ABVO. dated February 2, 1966.
↑ General Mountain Police Ordinance ( Memento of June 7, 2012 in the Internet Archive ), accessed on July 17, 2012; PDF; 233 kB.

Web links

Commons : Ventilation - collection of images, videos and audio files

Weather management (last accessed on December 20, 2012)

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

[Quelle_17-2] Wilhelm Hermann, Gertrude Hermann: The old collieries on the Ruhr. 4th edition. Verlag Karl Robert Langewiesche, successor to Hans Köster KG, Königstein i. Taunus 1994, ISBN 3-7845-6992-7 .

[Quelle_0-3] Mining Ordinance for all mining areas (General Federal Mining Ordinance-ABBBergV) Online (accessed on July 17, 2012; PDF; 145 kB).

[Quelle_16-4] The history of mine ventilation. Retrieved June 23, 2020 (43 pages, online at docplayer.org).

[Quelle_15-5] Georg Agricola: Twelve books on mining and metallurgy. In: Commission VDI-Verlag GmbH, Berlin.

[Quelle_14-6] Wilfried Ließmann: Historical mining in the Harz. 3. Edition. Springer Verlag, Berlin and Heidelberg 2010, ISBN 978-3-540-31327-4 .

[Quelle_2-7] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j Fritz Heise, Fritz Herbst: Textbook of mining studies with a special focus on hard coal mining. First volume, fifth improved edition. Published by Julius Springer, Berlin 1923.

[Quelle_3-8] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ ^o ^p ^q ^r Carl Hellmut Fritzsche: Textbook of mining studies. First volume, 10th edition. Springer Verlag, Berlin / Göttingen / Heidelberg 1961.

[Quelle_13-9] Friedrich Prinz, Edwarda Forster, Dirk Dahmann: Determination of the pollution of the mine weather by diesel engine emissions in hard coal mines underground. Reprint from the magazine “Hazardous Substances-Reinhaltung der Luft” Volume 58/1998 Online (accessed on July 18, 2012; PDF; 43 kB).

[Quelle_12-10] Ventilation of penetrable mine workings - main ventilation (accessed on July 17, 2012).

[Quelle_11-11] Carl Hartmann: Conversations-Lexicon of mining, metallurgy & salt works and their auxiliary sciences. Second volume, J. Scheible bookstore, Stuttgart 1840.

[Quelle_4-12] A ^b ^c ^d ^e ^f ^g Emil Stöhr, Emil Treptow: Basics of mining science including processing. Spielhagen & Schurich publishing house, Vienna 1892.

[Quelle_5-13] Albert Serlo: Guide to mining science. Second volume, 4th revised edition. Published by Julius Springer, Berlin 1884.

[Quelle_10-14] Wilhelm Leo: Textbook of mining science. Printed and published by G Basse, Quedlinburg 1861.

[Quelle_18-15] Fritz Heise, Fritz Herbst: Textbook of mining science with special consideration of hard coal mining. First volume, published by Julius Springer, Berlin 1908.

[Quelle_9-16] A ^b Emil Stöhr: Catechism of Mining Studies. Lehmann & Wentzel bookstore for technology and art, Vienna 1875.