Coal Seam Fire And Spontaneous Heating

Abhishek Kumar PandeyB. Tech Mining Engineering, IIT (ISM) Dhanbad

What is Mine Fire?

MINE FIRE

Oldest problem associated with mining industry.• In India its history can be traced back to 1865

when the first mine fire was reported in Raniganj Coal field.

Coal seam fire is the greatest challenge faced by the mining industry.

Coal fires are a serious health and safety hazard.

It can be defined as underground smouldering of a coal deposit, often in a coal mine.

Why should we be concerned about it?

Impacts

Mine fire causes massive destruction of affected areas and has social, economical, and ecological impacts.

Air Pollution: Besides destruction of the affected areas, coal fires often emit toxic gases, including carbon monoxide and sulfur dioxide.

Economical loss: China's coal fires, which consume an estimated 120 million tons of coal a year.

Social impacts: It not only effects the livelihood of workers working in the mines but also the peoples residing nearby. It creates an environment of fear in the society.

What is the cause behind it?

Origin

Fires in mine may be initiated due to various reasons. It may be of exogenous origin or endogenous origin.

Exogenous Fire: The fire is ignited from an external source of energy.• Open flames from explosion due to short firing operations.• Fire in conveyer belt due to frictional heating.• Ignition of the electrical equipment due to sparking.

Endogenous Fire: The fire which is caused due to spontaneous heating phenomenon of the fuel/material concerned (coal in this case). It is the major cause of mine fire.

The serious threat to mining industry Spontaneous Heating

The main cause behind the greatest problem of mining industry which turned tones of coal into ashes. More than 75 per cent of mine fire are caused due to the spontaneous heating.

The process of self heating of coal or other carbonaceous material resulting eventually in

its ignition without the application of external heat is termed as spontaneous combustion or spontaneous heating.

It generally takes place in goaves but can also develop in sides of coal pillars, and roof and floor strata of certain seams, and in coal stocks.

Factors leading to Spontaneous Heating

• Mining aspects influencing heating.• Presence of pyrites in coal which leads to oxidation of coal.• Relative humidity and sorption of water vapour in coal.• Bacterial action.

Apart from this, the oxidation of carbonaceous matter is the prime reason responsible for spontaneous heating

Study of Mine Fires at different mines

Dhori Colliery Mine Fire

Cause: The reason behind one of the biggest disaster in mining industry was the increase in amount of methane gas but the reason behind the ignition was the hurricane lantern carried by the worker.

Outcome: The disaster led to the death of around 265 peoples.

Bokaro and Ramgarh Mines Limited, Dhanbad, Bihar (at that time) (on 28-5-1965)

Sudamdih Colliery Mine Fire (on 4-10-1976)

Cause: It took place due to the accumulation of large amount of gas (methane). There was no clue about the reason for ignition. Outcome: 43 peoples lost their life in the fire.

Mine Fire Research Of US

The Mine Fire Research Of United States Reveals that most of the mine fires in US were outcome of flame cutting, welding operations and frictional heating. During the time period from 1990-2007, there were 1601 reportable fires that occurred in the U.S. mining industry (an average of 89 fires per year). The leading causes of U.S. mine fires include flame cutting and welding operations, frictional heating and ignitions, electrical shorts, mobile equipment malfunctions, and spontaneous combustion.

Graphical analysis of causes of mine fires in India (1969-89)

•

1969 1973 1977 1981 1985 19890

5

10

15

20

25

8

11

23

8

19

99

17

12

0

5

0

4

1

5

13

24

0 02

0 123

0

3

0 0

5 5

0 02 1

Spontaneous heating of coal undergroundSpontaneous heating of coal on surfaceSpontaneous heating of coal in open castFire in quarry from other causes other than spontaneous heatingOut-break of fire undergound from cause other than spontaneous heatingout-break of fire on surface from cause other than spontaneous heating

Year

No. o

f fire

s

How to deal with it?

Detection

“Earlier a fire is detected easier it is to deal with”The development of heating in a goaf is generally accompanied by the progressive appearance of-

• Haze

• Sweating of the strata.

• Gob stink or fire stink .

• Sound

• Smoke and fire

Though all these stages may not always be observed therefore may technological advancement and detecting appliances are being improved.

Detecting Instrument

These devices are based on the following phenomena:-

1. Energy changes occurring in the system.• Flame detector • Temperature measuring devices.

2. Material degradation of the affected fuel.• Smoke detectors • Product of combustion measuring devices.

Fire detector

Basic principle to stop a fire

The following three things are essential for the sustenance of any type of fire.

1. Availability of the fuel.

2. Necessary supply of oxygen

3. Adequate quantity of heat.

Withdrawal of any of these would lead to collapse of fire. For these to happen a number of methods

are being adopted.

Methods Of Extinguishing Mine Fire

1. Using chemical extinguishers.2. Application of water.3. Infusion of slurry/solid inert.4. Gel infusion.5. Inert gas infusion.6. Loading out of fire.7. Sealing off the fire.

What is outcome of the study?

Conclusion

• Mine fire is the burning the coal seams beneath the earth crust which have

hazardous consequences.

• The main reason behind the occurrence of mine fire in India is

spontaneous heating while in United States it is mainly due to frictional

heating.

• Developed detecting devices have made detection easy.

• Many times it is successfully detected but it is the negligence of the

employees which results in severe disaster.

Conclusion continues……

• Removal of oxygen through various chemicals and by the sealing off the fire.

• Water for removal of heat (latent heat of water =539 calorie/gm) .

• Removal of the hot combustible mass or the fuel

• Advancement in technology is required for the application of these methods.

Thank You