When coal exposes to air it undergoes Oxidation which gives out various gases such as carbon monoxide, methane etc. along with the evaluation of heat. the reaction takes place even at normal atmospheric temperature but when the temperature and the heat evolved reached ignition temperature of coal, coal catches fire.

1. SPONTANEOUS
COMBUSTION
SUBMITTED BY:-
MOHD ANAS (21)
B.TECH MINING 4TH YEAR
SPONTANEOUS COMBUSTION OF COAL
Author: MOHD ANAS
anas.mohd14@stu.upes.ac.in

2.  The process of self heating of coal or other carbonaceous material due to
auto oxidation resulting eventually in its ignition is termed as
“spontaneous heating”.
 It is the most important cause of fires in coal mines across the world.
 It has been a major problem in the leading coal producing countries like
China, Australia and India.
 In Indian coal mines, 80% of the coal fires occur due to spontaneous
combustion.
 The main reason is that the Indian coal seams are thicker and there is a
tendency of coal to spontaneous heating during depillaring operation.
• The process of self heating of coal or other carbonaceous material
due to auto oxidation resulting eventually in its ignition is termed as
“spontaneous heating”.
• It is the most important cause of fires in coal mines across the world.
• It has been a major problem in the leading coal producing countries
like China, Australia and India.
• In Indian coal mines, 80% of the coal fires occur due to spontaneous
combustion.
• The main reason is that the Indian coal seams are thicker and there
is a tendency of coal to spontaneous heating during depillaring
operation.

3. • Results in loss of lives and property.
• Causes considerable economic losses to the organizations and nation.
• Substantially increases greenhouse gas emanation levels and
responsible for environmental pollution.

4. • The Coal-Oxygen Complex Theory
• Pyrite Theory

5. • Establishment of peroxyl radical &
hydro peroxide.
• O2 get absorbed by coal on its surface
, which rapidly gives place a chemical
chain reaction.
• oxidation of certain constituent of coal
• Oxidation is exothermic which gave
huge quantity of heat
• Heat generated is greater than heat
dissipated, hence rise of temperature
• Rate of sorption of o2 will increase

6. • Coal containing iron pyrite in disseminated form is much liable to
spontaneous heating
• 2FeS2 + 7O2 + 16 H2O = 2H2SO4 + 2FeSO4 . 7H2O + 632 kcal
• The reaction of iron pyrites with oxygen and moisture gives products
of larger volume than the original pyrite hence opening more pore
area of exposure for oxygen, which is a exothermic reaction
• Less than 5% effect is negligible

7. • Chemical composition of coal
• Banded constituent of coal
• Friability
• Presence of iron pyrite
• Nature of adjoining strata
• Depth of seam
• Thickness of seam
• Geological disturbances
iron pyrite in coal

8. 1. Initial stage
• Faint haze
• Moisture deposition
• Faint odour known as gob stink
• Cricket and other small insects activity increase
2. Intermediate stage- petrol like odour
3. Final stage- tarry odour

9. • Bord and pillar method without Stowing
• Dimension, shape and size of pillar
• If depillaring is not taking for long time after formation of pillars
• If the mine is to be worked by longwall method of mining without stowing
• The longwall face should be in panel which can be sealed off in case of emergency.

10. Several methods and strategies which can be adopted to prevent and control spontaneous
combustion in coal are given as follows:
1. Mining layout
• Design of general mine layout should be simple.
• Panel system of working: appropriate for mining seams liable to sp. heating, which
facilitates effective sealing with a few stoppings.
2. Coal winning
• The coal should be won as completely as practicable especially in disturbed zones, thick
seams and strongly folded steep seams.

11. • A high rate of extraction should be adopted to prevent fire due to spontaneous
heating.
3. Ventilation and air leakage control
• All active mine workings and roadways in coal should be adequately ventilated and
unused roadways sealed off.
• Doors, stoppings, and regulators should be properly sited. Unnecessary stopping and
starting of main and booster fans should be avoided.
• Short-circuiting of air as well as its uncontrolled circulation must be eliminated

12. 4. Inhibitors
• Stacking ground should be concrete, free from growth of any vegetation
• Coal should be screened and uniform size should be stocked
• Coal stocks should be cleared first cum first basis
• Should be compacted by dozer to retard oxidation process.

13. REFERENCES
 R. D. Singh, Principle and practices of modern coal mining, new age
international publishers, Pp. 156-170
 www.Britania.com
 www.Researchgate.com
 www.Wikipedia.com