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Deep Mining in Solid Rock
Underground Mining
Ventilation
|
germ.: |
Streckenscheider, gemauerte Lutte |
|
span.: |
canal de ventilacion embovedado, huayrachina, huayracanyon |
|
TECHNICAL DATA: | |
|
Dimensions: |
air channel approx. 30 cm in width × 70 cm in height |
|
Extent of Mechanization: |
not mechanized |
|
Form of Driving Energy: |
differential air pressure and temperature |
|
Alternative methods: |
blowing or exhaust ventilation |
|
Mode of Operation: |
continuous |
|
Operating Materials: |
contruction material |
|
Type: |
rough rocks, loam |
|
ECONOMIC DATA: | |
|
Investment Costs: |
labor costs only |
|
Operating Costs: |
none |
|
Related Costs: |
none for mechanized ventilation fans |
CONDITIONS OF APPLICATION:
|
Operating Expenditure: |
low |————|———| high |
|
Maintenance Expenditure: |
low |———|————| high |
|
Personnel Requirements: |
none |
|
Location Requirements: |
none |
|
Ore Requirements: |
none |
|
Host Rock Requirements: |
Larger host-rock fragments should be generated during blasting for |
|
|
use in constructing the duct (huayrachina), requiring that the mine's |
|
|
drilling scheme be adjusted accordingly |
|
Regional Distribution: |
In earlier times, widely distributed in Latin America |
|
Environmental Impact: |
low |———|————| very high |
|
Suitability for |
|
|
Local Production: |
very good |———|————| bad |
|
Under What Conditions: |
limited to construction of the duct (huayrachina) |
|
Lifespan: |
very long |———|————| very short |
Bibliography, Source: Priester, Schauroth, Ponson, Winkelmann
OPERATING PRINCIPLE:
Huayrachina is a bricked duct erected on one side of the roadway floor. This method is suitable for ventilating mines with only one opening to the surface. On the surface, the huayrachina ends in a chimney or short ventilation raise in order to achieve the required pressure differential.
AREAS OF APPLICATION:
For ventilation of drifting or tunnelling operations. For ventilation of isolated activities in mines with natural ventilation.
REMARKS:
The natural mine ventilation is a natural air current which automatically replaces the mine air without human intervention. Natural ventilation is possible when a mine has at least two openings located at different topographic elevations. In special cases, natural ventilation can also temporarily occur in deep mines with two shaft or roadway openings of the same elevation. Natural ventilation results primarily from differences in temperature (and therefore air density), and secondarily from variations in humidity and air pressure, between the inside and outside air. Whereas in summer the air current normally flows In from the opening at the higher elevation through the mine to the lower opening, this flow pattern reverses direction In the winter months (see Fig. 3.2). The air current in deeper mines is stronger in winter than in summer.
The Huayrachina is suitable for blowing (forced) as well as exhaust ventilation.
Materials for constructing the wall are taken from the gob, which minimizes the transport distances required for the stones used to build the huayrachina and simultaneously reduces the volume of gob.
A disadvantage of this bricked brattice ventilation system is the inhomogeneity of cross-sectional areas and rough Inner surfaces of the huayrachina, resulting in high friction losses. In order to mechanize the ventilation, larger-capacity blower fans are therefore necessary.
A similar method of ventilation was applied already in the old Japanese gold mine of Sado, where two parallel drifts at an interval of approx. 0.5 m served to ventilate the mine.
SUITABILITY FOR SMALL-SCALE MINING:
Given the prerequisite of low labor costs, this method is appropriate even today, particularly for small-scale mining operations In Latin America. The ability to ventilate with exhaust fans, together with the almost unlimited lifespan and minimal cost of materials, fulfill the requirements for small-scale mining application.
Deep Mining General
Underground Mining
Ventilation
|
germ.: |
Kleine Wetterlufter, Wetterrad, Facher, Facherceblase, Centrifugalgeblase, Windtrumel, Focher |
|
span.: |
pequeno ventilador manual, rueda pare ventilacion, abanico, fuelle abanico, fuelle centrifungal, ventilador manual |
|
TECHNICAL DATA: | |
|
Dimensions: |
approx. 0.5 × 0.5 × 0.5 m |
|
Weight: |
approx. 20 kg |
|
Extent of Mechanization: |
not mechanized or mechanized |
|
Power Generated: |
80 W or more |
|
Form of Driving Energy: |
manual, pedal or with a small electric, pneumatic or internal- combustion engine |
|
Mode of Operation: |
continuous |
|
ECONOMIC DATA: | |
|
Investment Costs: |
probably around 500 DM (estimated value) when locally manufactured |
|
Operating Costs: |
labor costs only |
|
Related Costs: |
ducts, huayrachina, etc. |
CONDITIONS OF APPLICATION:
|
Operating Expenditure: | |
low |————|———| high |
|
Maintenance Expenditure: |
lubrication |
low |———|————| high |
|
Location Requirements: |
independent of location | |
|
Mining Method Requirements: |
due to the relatively small air-flow volume, should not be employed where larger open exacavation chambers exist to ensure a complete air exchange. | |
|
Replaces other Equipment: |
Other mechanized types of ventilation blower-fans For mining activities. | |
|
Regional Distribution: |
Earlier, generally widely distributed, today used only seldom for auxiliary ventilation. | |
|
Operating Experience: | |
very good |———|————| bad |
|
Environmental Impact: | |
low |———|————| very high |
|
Suitability for |
| |
|
Local Production: |
|
very good |———|————| bad |
|
Under What Conditions: |
qualified metal workshops where the fan-rotors, gears, etc. can be manufactured. | |
|
Lifespan: | |
very long |———|————| very short |
Bibliography, Source: Delius, Schauroth, DBM, v. Hauer, v. Humbolt
OPERATING PRINCIPLE:
Different types of centrifugal and axial-flow fans which circulate and displace the air by means of rotating blades. In centrifugal fans, air is drawn in near the blades' center of rotation where it is rotated, compressed and finally expelled outward due to inertia. With axial-flow fans, the air is tangentially accelerated by the rotating fan blades in an axial direction due to the generation of a pressure differential (higher pressure on the inner side of the blades where expelled air is compressed, and lower pressure at the suction side of the blades where the expelled air creates a vacuum).
AREAS OF APPLICATION:
Complete ventilation of mines.
Auxiliary ventilation.
REMARKS:
Manual fans are available from Delius (radial air compressor).
Manual fans were industrially produced in Germany until the beginning of this century (Pelzer, Wulf, Mortier) and were driven by means of cranks and gears up to velocities of 650 rpm.
SUGGESTIONS FOR DESIGN:
To serve as a gear drive, spur gears were placed at the rotor periphery. For pedal-driven fans, a chain-coupling would suffice, such as a bicycle chain.
SUITABILITY FOR SMALL-SCALE MINING:
For small-scale and minimally-mechanized operations, a manual or pedal-driven fan which is manufactured locally offers the possibility to ventilate artificially at low investment cost and without external energy input.
Fig.: Principle of natural
ventilation (left, flow in winter; right, flow in summer). Source: Armstrong.
Fig.: Small fans: left a pneumatic
fan, right an electric fan. Source: Armstrong
Fig.: A comparison of different fan
types (in cross-section); high-pressure fan (above), equal-pressure fan
(below)
Deep Mining General
Underground Mining
Ventilation
|
engl.: |
injector fan, venturi fan, air driver, venturi blower |
|
germ.: |
Luftstrahigeblase, Pneumatisches Strahlgeblase |
|
span.: |
ventilador neumatico de inyeccion |
|
Producer: |
Turmag |
|
TECHNICAL DATA: | |
|
Dimensions: |
diameter 200 mm, length 550 mm with 3 nozzles of 2-mm diameter |
|
Extent of Mechanization: |
fully mechanized |
|
Form of Driving Energy: |
compressed air, pneumatic |
|
Mode of Operation: |
continuous |
|
Output/Performance: |
air volume of 55 m³/min; fan type Altenkamp (1921) delivered 256.9 m³/min, intake fan: 0.667 m³/min |
|
Technical Efficiency: |
somewhat less than that of pneumatic turbofans |
|
Operating Materials: |
|
|
Type: |
compressed air to 4 bar |
|
Quantity: |
1.6 m³/min |
|
ECONOMIC DATA: | |
|
Investment Costs: |
If locally made, estimated to be as low as 400 DM; for Turmag fan, 618 DM + sales tax |
|
Operating Costs: |
costs to compress air |
|
Related Costs: |
costs of ducts |
CONDITIONS OF APPLICATION:
|
Operating Expenditure: |
low |———|————| high |
|
Maintenance Expenditure: |
low |———|————| high |
|
Location Requirements: |
independent of location |
|
Mining- | |
|
Method Requirements: |
Due to the relatively small pressure gradient between the intake and exhaust sides of the fan, the length of the ducts is limited (maximum of 100 m for a 200 - 300 mm duct) therefore, the mining procedure must be so designed as to ensure that a fresh-air intake is within close proximity of the area to be ventilated. |
|
Replaces other |
|
|
Equipment: |
other ventilators, manual as well as mechanized fans |
|
Regional Distribution: |
low |
|
Operating Experience: |
very good |————|————| bad |
|
Environmental Impact: |
low |———|————| very high |
|
Suitability for Local Production: |
very good |———|————| bad |
|
Under What Conditions: |
requires qualified metal and welding workshops |
|
Lifespan: |
very long |———|————| very short |
Bibliography, Source: DBM, manufacturer's information, Stout, Armstrong
OPERATING PRINCIPLE
Compressed air is blown through one or more small nozzles (2 - 3 mm 0 or larger) into an expansion chamber of the air driver. As the compressed air expands it draws additional air into the chamber, which has the form of a laval turbine. The ratio between compressed air and the quantity of air drawn in can reach 1 : 35.
AREAS OF APPLICATION:
Ventilation and auxiliary ventilation of mines, working faces or roadways with relatively short duct lengths.
REMARKS:
Air-drivers or infector fans are stable and have a long lifespan as a result of their simple design, which involves no driven moving parts. Therefore maintenance is minimal and potential repair work is simple.
SUITABILITY FOR SMALL-SCALE MINING:
For pneumatically-mechanized mining operations with small workings, locally-made air-drivers are superior to other pneumatic ventilators due to their stable design and maintenance-free operation.
Fig.: Design of an Air-driver.
Source:
Armstrong
Deep Mining General
Underground Mining
Ventilation
|
germ.: |
Wassertrommel, Hydrokompressor, Althaus'Geblase |
|
span.: |
toner de aguacompresor, hidrocompresor fuelle de Althaus |
|
TECHNICAL DATA: | |
|
Dimensions: |
approx. 3 m × 1 m × 1 m (HWL) |
|
Weight: |
approx. 100 kg |
|
Extent of Mechanization: |
not mechanized |
|
Form of Driving Energy: |
hydromechanic |
|
Mode of Operation: |
continuous |
|
Throughput/Performance: |
small capacities |
|
Technical Efficiency: |
substantially higher than other compressors, 8 - 15 % for a simple hydro-compressor |
|
Operating Materials: |
|
|
Type: |
water |
|
Quantity: |
relatively high |
|
ECONOMIC DATA: | |
|
Investment Costs: |
highly dependent on air pressure (higher pressure requires longer pipelines and better quality) |
|
Operating Costs: |
none |
|
Related Costs: |
for operation of compressor very high |
CONDITIONS OF APPLICATION
|
Operating Expenditure: |
low |———|————| high |
|
Maintenance Expenditure: |
low |———|————| high |
|
Operator Experience: |
little |
|
Location Requirements: |
requires water and a sufficient elevation difference |
|
Mining Requirements: |
A shaft is a prerequisite for the use of hydro-compressors. |
|
Replaces other Equipment: |
fan, small compressors |
|
Regional Distribution: |
No longer in use today; distributed throughout Central Europe earlier. |
|
Operating Experience: |
very good |———|————| bad |
|
Environmental Impact: |
low |———|————| very high |
|
Suitability for Local Production: |
very good |———|————| bad |
|
Under What Conditions: |
carpenter shop for fans, qualified metal workshop for compressors and fans |
|
Lifespan: |
very long |———|————| very short |
Bibliography, Source: Calvor, v. Bernewitz, Slotta in Eckholdt, Delius, Kircher, v. Hauer, Cancrinus, Wagner
OPERATING PRINCIPLE:
The water falls into a closed barrel where it strikes a reflecting plate, separating it from the air which has been drawn along with the water; this air is then directed through a duct to the working face.
The air-collection system can be designed using a water-jet pump (injector pump) of tubular construction (Bernewitz).
AREAS OF APPLICATION:
Blowing (forced) ventilation of smaller mines.
As a small
compressor for revolution of slurries, reagents etc. according to the air-lift
pump principle.
SPECIAL AREAS OF APPLICATION:
As a compressor to produce compressed air for driving pneumatic motors.
REMARKS:
Hydro-compressors were in operation until the early 1980s in the Harz Mountains mining region in Germany, whereby the output capacity of around 11 m³/min or 16.3 m³/min was somewhat low. The air pressure sufficed, however, for pneumatic drive units.
When used to generate compressed air, the separating of the air must occur under pressure, which is created by means of a standpipe for the expelled water. The height of the standpipe determines the pressurization of the compressed air.
SUITABILITY FOR SMALL-SCALE MINING:
The hydro-compressor for ventilation is a simple, stable apparatus without moving parts; it is locally available and suitable for small-scale mining. Prerequisites for its use, without exception, are the presence of water and an elevation gradient.
Its use as a compressor to produce compressed air appears less suitable due to the high construction costs. In situations where conditions permit the construction of a hydro-compressor (water, sufficient elevation gradient), a turbine-driven conventional compressor is probably more economical than a hydro-compressor for generating compressed air.
Fig.: Waterdrum for ventilation
porposes, by Cancrinus
Fig.: A Small hydro-compressor for
operating a cirulating pump according to the air-lift-pump principle for
circulation of agitation-leaching solution. Source: Bernewitz
Fig.: Working principle of a
waterdrum for ventilation purposes, by Wabner
Fig.: A waterdrum for ventilation
purpose. Source:
Calvör
Deep Mining General
Underground Mining
Ventilation
|
engl.: |
furnace ventilation |
|
germ.: |
Bewetterungsofen, Bartels Feuermaschine, Wetterofen |
|
span.: |
horno de ventilacion |
|
TECHNICAL DATA: | |
|
Dimensions: |
large oven-house or furnace with a chimney several meters high, or preferably underground oven in a by-pass with approx. 4 m hearth area |
|
Extent of Mechanization: |
not mechanized |
|
Form of Driving Energy: |
wood or coal-fired |
|
Alternative Forms of Energy: |
gas, oil |
|
Mode of Operation: |
semi-continual |
|
Technical Efficiency: |
20 - 80 % (in English mines) |
|
Operating Materials: |
|
|
Type: |
wood or coal |
|
Quantity: |
large, 30 - 50 k9/PSuseable × h |
|
ECONOMIC DATA: | |
|
Investment Costs: |
high |
|
Operating Costs: |
high, due to high fuel costs |
|
Related Costs: |
intake ducts, huayrachinas when only one opening exists |
CONDITIONS OF APPLICATION:
|
Operating Expenditure: |
low |————|————| high |
|
Maintenance Expenditure: |
low |———|————| high |
|
Location Requirements: |
wood or coal fuel must be available in sufficient quantities |
|
Deposit Requirements: |
only suitable for small excavation areas due to the small intake capacity |
|
Mining Requirements: |
the mining procedure must be so designed that only small excavation chambers are created |
|
Replaces other |
|
|
Equipment: |
fans |
|
Regional Distribution: |
historically used in Europe |
|
Operator Experience: |
very good |———|————| bad |
|
Environmental Impact: |
low |————|———| very high |
|
Suitability for Local Production: |
very good |————|————| bad |
|
Under What Conditions: |
adobe construction, metal hearth-grates |
|
Lifespan: |
very long |————|————| very short |
Bibliography, Source: Henning Calvor, Delius, A. v. Humboldt, Schauroth, Wagner
OPERATING PRINCIPLE:
The fire in the oven heats the air which then escapes through the chimney, drawing mine-air along with it; ducts direct the mine-air into the oven. Based on convection principle.
AREAS OF APPLICATION:
Exhaust ventilation of small mines where sufficient coal or wood is available. Also suitable as supplementary support for natural ventilation.
REMARKS:
It remains to be investigated if the effects of convective flow could be achieved through the use of solar energy (e.g. air collectors).
Ventilation ovens of this type are suitable for non-coal mining only in regions of abundant vegetation; unsuitable for regions of higher elevation with low vegetation density.
Use of ventilation ovens is appropriate especially in coal mining, where even products of poor market quality (for example, coal with high ash contents or poor carbonization, etc.) can be employed for firing the ventilation ovens.
Ventilation ovens have not only been constructed on the surface, but also underground, where the entire shaft served as a chimney, making this type of ventilation significantly more effective. The ventilation oven was in this case installed in a by-pass In a slightly-ascending roadway, whereby the correct quantity of air needed for combustion was regulated by ventilation doors and gates. The heat loss from the ovens is predominantly dependent on the humidity of mining air, leading to fluctuations in the efficiency between 80% in dry ventilation shafts to 20% in wet shafts.
An alternative method was also investigated in which the heat generated by coal combustion was used to heat water and convert it to steam, which then flowed under high pressure into an injector fan (jet-stream fan by Korting), drawing mine air along with it. The effect of this arrangement was however only minimal (efficiency only 2 % that of the ventilation oven).
SUITABILITY FOR SMALL-SCALE MINING:
Ventilation ovens are not recommended for small-scale mining because of their detrimental impact on vegetation. In isolated cases, the use of ventilation ovens in coal mines may be appropriate, however the associated risk of mine fires must be taken Into consideration.
Fig.: Above-ground ventilation oven,
by Wabner
Fig.: Installation of underground
ventilation oven in by-pass roadway, by Wabner
Fig.: Elevation and section of
ventilation oven constructed underground. Source: Wabner
Fig.: Ventilation oven or Bartel's
Fire Machine. Source: Calvör
Deep Mining General
Underground Mining
Ventilation
|
germ.: |
Bewetterungssegel, Windsegel, Machina Anemica, Windfang, Wetterhut |
|
span.: |
vela de ventilacion, vela de viento, machine anemica, cortaviento |
|
TECHNICAL DATA: | |
|
Dimensions: |
up to several m in diameter |
|
Weight: |
10 - 50 kg |
|
Extent of Mechanization: |
not mechanized |
|
Form of Driving Energy: |
wind |
|
Mode of Operation: |
intermittent |
|
Throughput/Performance: |
depends on resistance of the duct/huayrachina |
|
Technical Efficiency: |
high |
|
ECONOMIC DATA: | |
|
Investment Costs: |
very low |
|
Operating Costs: |
none |
|
Related Costs: |
an alternative ventilation system may be necessary; ducts or huayrachina must be installed |
CONDITIONS OF APPLICATION:
|
Operating Expenditure: |
low |————|————| high |
|
Maintenance Expenditure: |
low |————|————| high |
|
Location Requirements: |
locations of mine or shaft openings must be characterized by sufficiently strong daily and seasonal winds |
|
Mining Requirements: |
mine has to be designed for blowing (forced) ventilation |
|
Replaces other Equipment: |
mechanized types of fans, natural ventilation |
|
Regional Distribution: |
Australia |
|
Operating Experience: |
very good |————|————| bad |
|
Environmental Impact: |
low |————|————| very high |
|
Suitability for Local Production: |
very good |————|————| bad |
|
Under What Conditions: |
carpentry and/or other workshops where the manufacture of textile sails and wooden or metal frames can be combined |
|
Lifespan: |
very long |————|————| very short |
|
|
given that the construction is storm-resistant |
Bibliography, Source: Armstrong, Kircher, A. v. Humboldt, Loehneyss, Schauroth, Wagner
OPERATING PRINCIPLE:
A funnel-shaped extension of the duct is oriented with its opening toward the wind. The creation of a pressure head causes air to flow into the duct. The windsail is constructed of wind-permeable materials such as sail cloth, coated cotton or linen, or fiber-reinforced synthetic material. The wooden or metalic frame keeps the funnel open.
MODES OF OPERATION:
Ventilation of small mines where ducts or huayrachinas are present.
REMARKS:
During periods of insufficient winds, non-wind-dependent auxiliary ventilation equipment must be available.
Kircher describes a Machina Anemica, which is a wooden wind sail automatically aligned by use of a tail fin.
Schauroth indicates that combination blowing and exhaust ventilation sails have already been constructed, the simplest being at the opening of the shaft or drift, whereby the doors and gates were opened on the windward side for exhaust ventilation and on the leeward side for blowing ventilation.
Windsails are historically the oldest form of artificial mine ventilation.
Windsails of textile-construction, such as those currently used in small-scale mines in Australia, are preferable to those of wooden construction.
Aside from the mechanics for turning the opening toward the wind direction, windsails do not have moving parts and are therefore of sturdy construction. They should be designed to accommodate the strongest occurring winds.
In downcast ventilating shafts in dry locations, ventilation can be enhanced by cooling the intake air with a fine water mist which is sprayed Into the shaft. The evaporation effect cools the air flow; the higher the air temperature and the lower the relative humidity, the stronger the cooling effect.
SUITABILITY FOR SMALL-SCALE MINING:
The use of wind sails in Latin American small-scale mines is only practical where sufficient winds occur on a regular daily or seasonal basis near the shaft or mine entrances.
Fig.: Types of historical windsails
applied primarily for bowing
ventilation.
Deep Mining General
Underground Mining
Ventilation
|
germ.: |
Kastengeblase |
|
span.: |
soplador de cajon |
|
TECHNICAL DATA: | |
|
Dimensions: |
e.g. 3 square pistons, 1 × 1 m surface area; box: 4 × 1.2 × 5 m LWH |
|
Weight: |
approx. 1,000 kg |
|
Extent of Mechanization: |
partly mechanized |
|
Power: |
starting at approx. 0.5 kW |
|
Form of Driving Energy: |
waterwheel (as for the box Freiberg) blower of above-mentioned dimensions in |
|
Alternative Forms: |
other slow-moving driving mechanisms |
|
Mode of Operation: |
semicontinual |
|
Technical Efficiency |
420 m³/h air volume with 450 mm water column pressure |
|
Operating Materials: |
|
|
Type: |
lubricant |
|
Quantity: |
small quantities |
|
ECONOMIC DATA: | |
|
Investment Costs: |
approx. 2,000 DM |
|
Operating Costs: |
depends on drive-system, however generally very low |
|
Related Costs: |
drive-system, air channel system (ducts, etc.) |
CONDITIONS OF APPLICATION:
|
Operating Expenditure: |
low |————|————| high |
|
Maintenance Expenditure: |
low |————|————| high |
|
Replaces other Equipment: |
all other blower systems for auxiliary ventilation |
|
Regional Distribution: |
to date not distributed in the Latin American small-scale mining industry |
|
Operating Experience: |
very good |————|————| bad |
|
Environmental Impact: |
low |————|————| very high |
|
Suitability for Local Production: |
very good |————|————| bad |
|
Under What Conditions: |
as traditional wooden system, possibly also produceable as plastic, fiberglass-reinforced resin, etc; valves of leather and felt for sealing, possibly also of rubber. |
|
Lifespan: |
very long |————|————| very short |
Bibliography, Source: Wagenbreth, Grube Alte Elisabeth/Freiberg
OPERATING PRINCIPLE:
Air contained in the compression chamber of the wooden box is compressed by tightly-fitting wooden pistons which work in two opposite directions. Each wooden box accordingly has an inlet and an outlet valve for each of the two compression chambers, which are separated by the piston in between. As the piston travels in one direction, the air in front of it is compressed and driven out through a simple flap valve. When the piston has reached the end of the stroke and reverses direction, the flap valve closes gravitationally and the suction valve opens due to the pressure drop behind the piston, letting fresh air into the chamber. In the other chamber, now in front of the piston, the air is compressed and then driven out the respective flap-valve in that chamber. With each piston stroke and corresponding direction change, air is alternately compressed and expelled from the one chamber while fresh air is drawn into the other. A cross head Joint assures that the pistons travel parallel to their axis. As an alternative, Watts' parallelogram system can be used in conjunction with a beam.
Box blowers are generally constructed in an upright position where the driving-axle is vertical; all other constructions have experienced significantly higher friction losses and sealing problems.
AREAS OF APPLICATION
Compressing of air for ventilation and forge furnaces
SUITABILITY FOR SMALL-SCALE MINING:
Box blowers are suitable for ventilation of small mines where waterwheels or slow moving drive-systems exist.
Fig.: Box blower for ventilation,
driven by a steam engine with balancing beam and Watt's Parallelogram
construction, by Wabner
Fig.: Horizontal box blower, by
Wabner
Deep Mining General
Underground Mining
Ventilation
|
germ.: |
Glockengeblase, Harzer Wettersatz, Baader'sches Geblase |
|
span.: |
soplador de campana, equipo pare ventilacion del Harz, soplador de Baader |
|
TECHNICAL DATA: | |
|
Dimensions of one blower unit: |
approx. 1 m in dia., 2 - 3 m in height |
|
Driving Output: |
100 W or more |
|
Extent of Mechanization: |
not or semi-mechanized |
|
Form of Driving Energy: |
manual or hydromechanic |
|
Alternative Forms: |
pedal drive, animal-powered gear |
|
Mode of Operation: |
intermittent |
|
Throughput/Performance: |
per stroke approx. 2 m³ air, frequency approx. 6 strokes/min |
|
Technical Efficiency: |
very high, due to low frictional losses |
|
ECONOMIC DATA: | |
|
Investment Costs: |
very low, < 550 DM |
|
Operating Costs: |
dependent upon extent of mechanization |
|
Related Costs: |
duct, conduit or huayrachina nessesary |
CONDITIONS OF APPLICATION:
|
Operating Expenditure: |
low |————————| high |
| |
depending upon extent of mechanization |
|
Maintenance Expenditure: |
low |————|————| high |
|
Personnel Requirements: |
low |
|
Location Requirements: |
none |
|
Replaces other Equipment: |
natural ventilation, blower |
|
Regional Distribution: |
historical only (Harz, Germany) |
|
Operating Experience: |
very good |————|————| bad |
|
Environmental Impact: |
low |————|————| very high |
|
Suitability for Local Production: |
very good |————|————| bad |
|
Under What Conditions: |
simple metal or wood manufacturers, leather or rubber valves |
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Lifespan: |
very long |————|————| very short |
Bibliography, Source: German Museum, Slotta in Eckhlodt, A. v. Humboldt, v. Hauer, Schauroth, Wagner, Treptow
OPERATING PRINCIPLE:
A small, bottomless bell-shaped or cylindrical container is continually moved up and down in a water bath within a larger open-topped container. This causes a constant increase or decrease of air space volume in the upper portion of the inside vessel, like a bellow. A pipe connecting the ventilation duct to the head of the inner container is equipped with valves to direct the air flow.
AREAS OF APPLICATION:
Ventilation and auxiliary ventilation in small mines and drifts.
REMARKS:
In the 18th century in the Harz mining region in Germany, drifts up to 3 km in length were ventilated with Baaders blowers (invented by Josef Baader, 1789). At that time, wooden ventilation ducts (hollowed out logs) were used which were connected and sealed with metal rings.
Depending on the valve type, exhaust or blowing (forced) ventilation is possible. The simultaneous operation of two Baader's blowers counterposed on a tilting beam can produce a continual air flow. Compared to all other designs of bellows, box blowers, etc., Baader's blower is distinguished by its very low friction losses and high performance efficiency.
It would be worth investigating to what extent Baader's blowers could be animal-powered.
SUITABILITY FOR SMALL-SCALE MINING:
Low investment costs, a simple operating principle and its suitability for local production make Baaders blower appropriate as one of the simplest method for artificial ventilation. Slowly-moving drive systems are most suitable.
Fig.: Design section of a bell-shaped
blower. Source: Slotta, in: Eckhold
Fig.: Schematic diagram of a Baader's
blower (Harzer Wettersatz). Source:
Lempe
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