Mining engineering 3rd semester mining environment

Helps to know about mining conditions and minerals . their importance and occurance

1. National Institute of Technology
Raipur Chhattisgarh 492010
Subject : Mine environment I
Topic:-Mine gases and
their origin & occurrence
Presented by:-
Akshay Gupta 23121007
Aman Kumar 23121008
Aman Soni 23121009
Aman Dhar diwan 23121010
Amit Kumar 23121011
Animesh Kumar 23121012

2. Mine Gases.
Mine gases, also known as damps, area toxic or explosive mixture of
gases that can be found in mines.These gases can be harmful to
human health and mine safety.Some of the most common mine
gases include:
Oxygen (O2).
Methane (CH4).
Carbon dioxide (CO2).
Carbon monoxide (CO).
Nitrous fumes (N2).
Hydrogen Sulphide (H2S).
Sulphur Dioxide (SO2).

3. Gas mixture terms used
for mines.
Firedamp –Methane.
Afterdamp -Gases formed after the coal dust
and firedamp explosion.
Blackdamp –Mixture of carbon dioxide and
nitrogen .
Whitedamp –Carbon monoxide.
Stinkdamp –Hydrogen sulphide.

4. Oxygen
Physical properties:-
Oxygen is colorless , odourless and tasteless
gas .
Its molecular weight is 32 g/mol.
Its specific gravity is 1.105.
Oxygen can cause a dangerous condition in
a mine by its absence .

5. Origin & Occurrence
The origin of oxygen in mines is primarily due
to few factors:-
1. Ventilation System:-Modern mines are
equipped with ventilation system that supply
fresh air to underground areas these involve
pumping of air from surface.
2. Oxygen Generation:-In very deep and
isolated mines oxygen may be generated on
site using electrolysis.
3. Natural ventilation:-This can occur through
the natural flow of air between the surface
and underground environment.
4. Natural air flow:-This natural flow can help
in maintaining oxygen levels in mines.

6. Methane CH4
Physical properties :-
Methane is a colorless , odourless and tasteless
gas.
1kg of Methane at NTP (273.15K and 101.33kPa)
has a mass of 0.71kg
Methane become liquid below 112K and
solidifies below 90K.
It is poorly soluble in water.
It is lighter than air having specific gravity of 0.56.

7. Origin & Occurrence
Bacteria Decomposition:-Bacteria decomposes cellulose and
lignin producing methane and carbon dioxide . It is also called
as marsh gas .
Coal Beds and Shales:-In coal mining, methane is often found
within the coal seams themselves. It is adsorbed onto the surfaces
of the coal and can be released during mining activities.
Methane can also be found in associated shale formations.
Geological Formation:-Methane is primarily formed from the
decomposition of organic matter buried deep in sedimentary
rock formations.
A fraction of these gases escape during coalification (the process
by which organic material like vegetation are transformed into
coal over a time period ). The specific methane emission ,
defined as the methane emitted per ton of coal.

8. Carbon Dioxide CO2
Physical properties:-
It is colorless and odourless and has a slightly
acidic taste .
The specific gravity of carbon dioxide is 1.519.
It is fairly soluble in water and forms carbonic
acid.
Carbon dioxide can occurs both in coal and
metal mines.
A mixture of carbon dioxide(the concentration
of CO2 may vary from almost negligible to 20%
)and nitrogen is known as blackdamp.

9. Origin & occurrence
Carbon Dioxide is produced from a variety of sources including
strata emission (the release or discharge of material from different
layer or strata) , oxidation of carbonaceous material.
It is also produced by internal combustion engines , blasting , fires ,
explosions and respiration.
Exhalation of men:-They bring oxygen to our body and leaves
carbon dioxide.
Burning of light:-When something burns it produces carbon dioxide.
Decay of timber:-It is caused due to excessive exposure to moisture.
Oxidation of coal:-When carbon in coal combines with oxygen in air
it produces carbon dioxide.
Blasting of explosives Or mine fires:-The heavy action of an explosive
is a result of the large quantity of rapidly expanding hot gases
produces it detonates as carbon dioxide and nitrogen.

10. Carbon
monoxide CO
Physical properties:-
CO is colorless and odourlesswith a specific
gravity of 0.972.
It burns with the blue flame and is explosive in
presence of air concentration between 12.5%
and 75%.
The ignition temperature of CO is 873K.
Though CO is an inflammable gas this fact is no
practical importance in mining because it never
cause in significant concentration to burn or
cause explosion.

11. Origin &
occurrence
Active mine fires:-An active mine fire is a fire that
occurs in an active or abandoned coal mines.
Coal dust explosion:-It is a process of rapid oxidation
between oxygen in air and coal dust under the action
of high temperature or heat source.
Firedamp explosion:-It is an explosion caused by the
release of flammable gas or firedamp that builds up in
coal mines.
Exhaust of Diesel locomotive:-It is a complex mixture of
gases and particles produced by the combustion of
diesel fuel in diesel locomotive.
Timber fire
Blasting

12. Nitrous fumes or nitrogen N2
Physical properties:-
Nitrogen is colorless , odourless and tasteless gas .
It is slightly lighter than air with a specific gravity of 0.967.
It is usually inert and does not support ignition.
It has low solubility in water.

13. Origin &
occurrence
Decomposition of organic substances:-It is the
process of breaking down dead organic
substances into simpler organic or inorganic
matter.
Blasting using explosives :-Blasting is the process of
using explosive to fragment material such as rock ,
by breaking them down into smaller pieces.(1kg of
nitroglycerine release 0.135 m3 N2).
Tunnel and shafts with a heavy shot firing
Exhaust fumes of Diesel locomotive

14. Hydrogen
sulphide H2S
Physical properties:-
It is heavier than air and highly
soluble in water.
It is combustible in nature.
It has wide explosibility range
between 4.3% to 45.5%.
It burn with a light blue flame.

15. Origin and occurrence
Occurs in Afterdamp:-Afterdamp is a toxic mixture of
gases left in a mine following an explosion caused by
methane rich firedamp this occur hydrogen sulphide.
Methane blowers:-A methane blower is a device that
can move methane gas from one place to another
place and may occur hydrogen sulphide.
Gob fires:-It is the fire that occur in the gob area of
coal mine and are often caused by spontaneous
combustion of residual coal that occurs hydrogen
sulphide.
Produced by metal mines by the action of acid:-
FeS2 + H2O = Fe(OH)2 + H2S + S .
By blasting in heavy sulphide ores.

16. Thank you