A new method is proposed that can be implemented in case of mine fire. One of the most fatal accidents in Mining is outbreak of mine fire, this method helps to isolate the area under fire and simultaneously tries to diminish the fire to prevent coal loss.
3. INTRODUCTION
The main objective of mine
ventilation is the provision of
sufficient quantities of air to all the
working places and travel ways in an
underground mine to dilute to an
acceptable level those contaminants
which cannot be controlled by any
other means. Where depth and rock
temperatures are such that air
temperatures are excessive,
mechanical refrigeration systems
may be used to supplement the
beneficial effects of ventilation.
4. DEVICES USED FOR VENTILATION
1. VENTILATION STOPPING:
These have to be made of
incombustible material and are therefore
of brick or stone. The thickness of a
ventilation stopping is min. 38cms of
brick or stone in lime or cement and
plastered to prevent leakage of air.
PERMANENT STOPIING
5. 2. Aircrossing:
These are constructed where
intake air and return air
currents have to cross each
other. These should be leak-
proof, fire- proof and have
ample cross-section.
Normally it is constructed at a
place where it has reasonably
long life and the ground is free
from rock movement.
Air crossing in gassy coal mines
should be explosion-proof.
MODEL FOR AIRCROSSING
6. 3. Ventilation Doors:
These are used on those
roads which are required for
haulage or travelling purpose.
The ventilation doors must be
arranged to close automatically
and with this object the frame
of the door is so fitted that the
top leans about 50mm-70mm
forward in the direction of air
pressure. The door, of course,
should be open against the
intake air so that the air
pressure normally keeps it
closed.
7. 4.Regulator :
It is a window of adjustable opening in a brick stopping. The
shutter of the regulator can be locked in position to prevent
tampering by workers.
Introduction of regulator in a roadway increases the
resisitance to air current and therefore should be used on
return side of a district whose ventilation has to be reduced
and fixed in a place where all the air of the district has to
pass.
The regulator has the effect of reducing the air flowing in the
regulated split and at the same time increasing the volume of
air flowing in unregulated split.
8. 5. Fans:
To achieve the high pressures necessary to cause the air to flow through
long lengths of duct, multiple fans with either contra-rotating or co-
rotating impeller arrangements may be used. Air leakage is the greatest
problem in auxiliary fan and duct systems, particularly over long
distances. Rigid ducts fabricated from galvanized steel or fibreglass, when
installed with gaskets, have suitably low leakage and may be used to
develop headings up to several kilometres in length.
9. 6. Ducts:
Flexible ducts are considerably
cheaper to purchase and easier to
install; however, leakage at the
couplings and the ease with which
they are ripped by contact with
mobile equipment results in much
higher air losses. Practical
development limits using flexible duct
rarely exceed 1.0 km, although they
can be extended by using longer duct
lengths and ensuring ample clearances
between the duct and mobile
equipment.
10. TYPES OF NATURAL VENTILATION
Ascensional:
It implies taking the intake
ventilating air to the lowest
point of a district or face and
allow it to travel to higher
levels to ventilate the district or
face before it goes to the
return.
Desenctional:
It implies taking the air to the
rise side of a district and allow
it to travel to lower levels as it
ventilates the working places.
11. REQUISITES IN PROPOSED PLAN
Fire-proof Curtain
Sensors
Alarm
Absorbent
Extinguisher
Sprayer
12. CSP’s innovative Activ-Films® offer the
ability to address a wide variety of product
stability needs in ways that are invisible to
the consumer and more efficient for the
manufacturer. This makes Activ-Films® ideal
for applications ranging from foil pouches,
stick packs and blister packs to substrates
for diagnostic test strips.
Incorporating our patented three-phase
Activ-Polymer® technology helps protect
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Activ-Films® can be formulated for moisture
absorption, gas absorption or the release of
ClO2 or other agents.
ABSORBENT
13. Activated through exposure to UV light on the
packaging line, these films do not need
moisture to be effective and are effective at
low relative humidity. CSP's oxygen scavenging
films can consistently reduce O2 levels below
1%.
Speciality: It can absorb oxygen from
100mts range in 2 minutes.
14. EXTINGUISHER
The extinguishing powders used in
powder extinguishing systems are
highly efficient, quick-acting
extinguishants. The sudden
extinguishing effect of the powder
cloud is caused by the suffocation
effect and the anticalytic effect, a
chemical intervention into the
combustion process. Extinguishing
powders mainly consist of non-
poisonous inorganic salts mixed with
waterproofing and pouring agents.
They are used for fires with solid,
liquid or gaseous substances and for
metal fires, thus, they are used for fire
classification A, B, C and D.
15. Powder fire extinguishers with
Eurotroxin and Eurotroxin S
powder ensure powerful extinguishing
through the formation of a powder cloud,
which provides effective protection against
heat during the extinguishing process.
Powder extinguishers, which are also
available as stored pressure extinguishers
with 6, 9 and 12 kg of solution, are frost-
proofupto-30ºC.
16. SPRAYERS
The coal dust explosion prevention can be
done using a low pressure spray gun
sprayer direction of excavating working
surface of the conveyor belt and the
deposition the place of the coal dust spraying
thickness is 0.5 percent of Polyvinyl
Alcohol water solution; Because the
polyvinyl alcohol is high molecular polymer
fog polyvinyl alcohol adhesive it can absorb
dust particle and quickly drop to the ground
is reduced effectively in air and coal dust
concentration. Using this method the need to
use the cleaning method and watering and
washing method is eliminated and it does not
need to spreading rock powder and it saves
manpower physical resources financial.
COST: US $1,000 - 2,700 / Metric Ton
20. Fire-Proof Curtain :
CarbonX flame resistant fabric deleiver the ultimate
level of protection significantly outperforming competitor.
In field test conducted over the force of several years and
across multiple applications, our flame retardant fabrics
have consistently proven their ability to withstand heat
and direct flame for up to 20 times longer than
competitive products.
Cost: Rs.80/mt (but in bulk Rs.50/mt)
21.
22. EMERGENCIES IN UNDERGROUND MINES
1. MINE FIRE –
Coal fires are a serious health and
safety hazard as well as affecting the
environment by releasing toxic fumes,
reigniting grass, brush, or forest fires,
and causing subsidence of surface
infrastructure such as roads, pipelines,
electric lines, bridge supports, buildings
and homes. Whether started by humans
or by natural causes, coal seam fires
continue to burn for decades or even
centuries until either the fuel source is
exhausted.
23. 2. COAL DUST EXPLOSION-
A dust explosion is the
fast combustion of dust particles
suspended in the air in an enclosed
location. Coal dust explosions are a
frequent hazard in
underground coal mines.
Dusts have a very large surface area
compared to their mass. Since
burning can only occur at the
surface of a solid or liquid, where it
can react with oxygen, this causes
dusts to be much more flammable
than bulk materials.
24. 3.Firedamp-
Firedamp is flammable gas found in coal mines. It is the name
given to a number of flammable gases, especially methane. It is
particularly commonly found in areas where the coal
isbituminous. The gas accumulates in pockets in the coal and
adjacent strata, and when they are penetrated, the release can
trigger explosions. Historically, if such a pocket was highly
pressurized, it was termed a "bag of foulness"
25. PRESENT SCENERIO
The chief measure of ventilation control in the event of fire
is the provision of fire doors. These are in the form of
fireproof (usually steel) doors installed in suitable leak-
proof stoppings which are normally kept open.
Such fire doors are generally erected both at
inbye and outbye of working panels and district so that any
fire in such a district can be quickly sealed after withdrawal
of men.
Sometimes the door flap may be taken off its hinges and
stored alongside for quick installation in case of emergency.
28. In this method we put areal sensor with alarm in triangulation ways
so that it covers maximum area .
In this method there are two curtains placed in intake and return
gate.
If any hazard occurs in mine, sensor detects change in
concentration of gases like percentage of CO2 and CO present in
mine atmosphere which gets increased.
The sensor then activates the two curtains placed at the intake
and return side of the district .
The intake and return airways consist of two sliding doors back
coated with absorbent layer of active films of cps technology.
The door gets closed after 8 minutes of detection of fire by sensor
and by the siren of alarm which also activates as soon as the
sensor detects fire
31. In this method, the curtains are placed near to the working face i.e. in
front of the developed pillars which are being left for depillaring.
In this method, as soon as the battery operated sensor detects the
concentration of gases the sensor activates the alarm which then
operates the roller curtain which then operates the extinguisher and
sprayer.
The extinguisher will extinguish the fire if caught and sprayer sprays
material in powedered form which gets mixed with the mine air present
there and supresses the coal dust explosion from taking place.
The roller curtain which is opened is being coated with absorbent layer on
one side i.e side opposite to the working face where fire is being caught.
The roller curtain consist of active film which reduces oxygen
concentration to below 1% within few minutes of activation of alarm, so
that no oxygen is being present for further fire to take place.
Now, the working at the face is not being hampered due to occurrence of
fire at any of the pillars which divers the ventilation instantly from the fire
area.
32. NOW, WHAT HAPPENS IF THE
SENSOR FAILS TO DETECT
THE ROLLER CURTAIN WILL ALSO BE MANUALLY OPERATED SO IF ANY
(OVERMAN OR MINING SARDAR ) DETECTS THE FIRE IN THAT AREA
AND THE SENSORS IN TECHNICALLY FAILED CONDITION CAN ALSO
CAN’T HAMPER THE WORKING AT THE FACE AND VENTILATION
DIVERSION.
38. In this case, there will separate curtains for each row
and line sensor for each line of pillars being placed
In this arrangement as soon as the fire is detected by
any one of the line sensor then the sensor which is also
battery operated operates the curtain along rows and
the curtain which is placed in parts near to the face.
The curtain fall down brings the oxygen below 1% at the
line of pillars and hence the complete panel is
surrounded as at the packed place Extinguisher and
aprayer also works to bring down the fire and coal dust
explosion.
43. CONCLUSION
1. This is a newly proposed idea which need a wide
research to apply in the mining condition.
2. Continuous output can be obtained even in case of any
hazard( open fire, coal dust explosion etc.) if this idea
is applied.
3. It could look superficial now since, no experimentation
of this method is has been done.