"Many researches have been made to predict and mitigate in spontaneous combustion of coal which have failed at times due improper monitoring and conventional methods of its early detection. Here is a paper presents methods that shall be the future face of mining industry which is taking avid steps to encourage IT and other technologies to fight against such problems"

1. Prepared By :
Sujit Surendran
Saroj Raj Kumar Ramnaresh
Katariya Prashant Rameshbhai
Future Approaches To Cope with Spontaneous Combustion
Government Engineering College - Bhuj

2. Future Approaches To Cope with Spontaneous
Combustion
Prepared Under the guidance of
N.N. Mupkalwar
Mining Department
Government Engineering College -Bhuj

3. Theme Of Our Project
Fires in coal mines can be categorised into two
groups, Viz. –
A) Fires resulting from
spontaneous combustion of coal and
B) Open fires – which are
accidental in nature and are caused because of
ignition of combustion materials. Here, in this
paper we are going to discuss for –
“Group A)” kind of fires – its detection,
prevention techniques and newly developed ideas
which can bring about a revolutionary change in the
face of Safety in Mines. SPONTANEOUS COMBUSTION IN OPENCAST MINES

4. What Is Spontaneous Combustion ?
“SPONTANEOUS COMBUSTION OF COAL DEFINED
AS THE PROCESS OF “SELF-HEATING” RESULTING
EVENTUALLY IN ITS IGNITION WITHOUT THE
APPLICATION OF EXTERNAL HEAT.”
MAINLY CO, CO2, WATER VAPOR ALONG WITH
THE EVOLUTION OF HEAT DURING THE CHEMICAL
REACTION. THE PROCESS TAKES PLACE AT NORMAL
TEMPERATURE, BUT IT IS SLOW AND THE HEAT
EVOLVED IS NOT PERCEPTIBLE AS IT IS CARRIED
AWAY BY AIR UNLESS AIR IS STAGNANT.

5. How Spontaneous Combustion Leads to fire
The Fire Triangle
OXIDATION OF COAL (FUEL) AND HENCE –
PRODUCTION OF HEAT
IF HEAT NOT DISSIPATED, TEMPERATURE OF
COAL INCREASES
OXIDATION INCREASES AT HIGHER
TEMPRETURE- IGNITION POINT REACHED
FIRE

6. Future Approaches To Cope with Spontaneous Combustion
MAJOR DETECTION TECHNIQUES :
“Radon Detection Technique”
“Thermal Remote Sensing”
“Infrared Technique”
“Installing Smell Sensors & Thermal
Survey”
PREVENTION AND CONTROL BY :
“Colloid Injection Technique”

7. Radon Detection Technique
Principle of Radon-Detection Technique
 U-238 is a common rare element in rock strata, as is its
decay product Rn-222 (radon) and radon progeny.
 Radon has a strong diffusion ability. Activated carbon,
silica gel, polyethylene and some other materials can
easily adsorb radon and its progeny.
 This property enables radon and its progeny to be easily
collected from the surface with a container coated with
these adsorbents and analyzed.
 Experimental test data show that when the coal is
heated up, the emanation rate of radon from overlying
strata will increase.
 This relationship, combined with radon radioactive and
its unique properties form the fundamental principle of
radon-based detection techniques for coal sponcom.

8. Radon Detection Technique
KEY INSTRUMENTS
USED :
Adsorbents :
Activated charcoal
silica gel and
polyethylene
Alpha Cup
Radon Detector
Alpha Cup Radon Detector
Ionization Chamber inside a
Radon Detector which takes
the readings of a Radon-222
Emanations.

9. Radon Detection Technique
OPERATION AND ANALYSIS :
 After the survey area is decided the grid pattern
is designed.
 Measurement spacing point can be 20 m×20 m,
15 m×15 m or 10 m×10 m, depending on site
conditions.
 An auger machine is used to dig holes for
placing alpha cups. Hole is 30 cm in diameter
and 30-40 cm in depth.
 Cups are analyzed and radon detectors is used
to take the CPM values.
 A program used produces a 3D map of
abnormal.CPM values, and the location of
“high-temperature” area.
Detection Point and Collection Cup
Hot spots detected with the radon technique.
Sample of Grid Pattern

10. Radon Detection Technique
Merits of Radon Detection Technique :
 It can remotely locate abnormal temperature
areas. Its accuracy for locating the sponcom
center is 90%. Detection depth is up to 800 m.
 It is of high suitability, low cost and easy to
operate
 It has a high reliability and is largely unaffected
by external factors.

11. Thermal Remote Sensing and Infra-Red Techniques
Principle of Infrared Detection Techniques
 All warm (warm defined as being above “0 Kelvin” in
temperature) objects’ atoms, molecules, and electrons
are always in motion, vibrating and radiating (emitting)
infrared waves, forming in infrared radiation field.
 As the object’s temperature increases, the intensity of
the radiation increases. The radiation field can be
characterized by its energy, momentum, direction and
other information.
 Like any other objects, a coal seam is also emitting
infrared waves. If there is a spontaneous combustion in
the coal seam, this should be reflected in the
characteristics of its infrared radiation field.

12. “Thermal infrared remote sensing systems” record thermal infrared images that can be used to determine the type
of material in certain instances based on its thermal emission characteristics and evaluate if significant changes have taken
place in the thermal characteristics of these phenomena over time. It is obvious that coal fires will heat the ground around
them even when they are located underground, provided that they are not at a great depth.
Thermal Remote Sensing and Infra-Red Techniques
The process of remote sensing can be briefly described by the
following steps:
 Energy source illuminates/provides electromagnetic energy to
the target.
 Radiation energy travels from the source to the target.
 Interaction with target – depending on the properties of both
target and radiation.
Within the overall thermal infrared region, the 3-5μm and 8-14μm
regions are used in thermal remote sensing as in the intervening
part of the electromagnetic spectrum the energy is greatly
absorbed by the atmospheric gases.

13. Thermal Remote Sensing and Infra-Red Techniques
Thermal infrared radiation of an object is controlled mainly by several factors:
i.The emissivity of the object,
ii. Its geometry and
iii. Its temperature.
Why acquire data at night ?
Coal fires on the surface, when present as flaming combustion, emit significant thermal energy that is easy to detect by
any remote sensing scanner. Some of these may be at a high enough temperature to become visible in wavelengths. In
the case of a subsurface coal fire the surface heating is comparatively subdued and may be masked by the solar heating or
reflected solar thermal radiation during the day. In that case it is necessary to use night-time remote sensing data to
reveal and measure the extent of heating. Coal fire detection using remote sensing has three major steps:
 Acquire a thermal image (preferably night) of the area under investigation using remote sensing and process digitally
to create a surface temperature map to reveal the temperature anomalies,
 Acquire information about local geological setting, temperatures of coal fire vents and different land covers through
field survey,
 A final temperature map calibrated with field collected temperatures to reveal the coal fires.

14. Thermal Remote Sensing and Infra-Red Techniques
Use of Handheld Infrared camera /Infrared detector in a localized area of a mine.
A thermal imaging camera works similar to a normal video camera.
The glass of a normal video camera doesn’t transmit infrared radiation well. The infra-red camera is equipped
with germanium glass which is a good transmitter of infra-red radiation.
Sensor
Electronics
LCD SCREEN
Infrared radiations coming
from an object
Infrared
detector
transforming a
infrared image into
radiometric
Calculated temperature
values from the image. Note : Before capturing a
thermal image the camera is to
be set with correct emissivity.
The camera is preloaded with
“Emissivity table” for certain
objects.

15. Thermal Remote Sensing and Infra-Red Techniques
A thermal Image of Stockpile
A thermal imaging camera

16. Thermal Remote Sensing and Infra-Red Techniques
1.Layout of measurement points :
Measurement stations are set along the gate road
to be surveyed. Each measurement station covers a
number of adjacent measurement points in the
ribs, roof and floor.
Schematic layouts of measurement stations and points with the infrared technique
2.Field Measurement:
An infrared camera is used to measure the strength of the energy field of infrared radiation and surface temperatures of the
measurement points. If a zone of abnormal strength is recorded, then repeated measurements in that zone are undertaken.
3.Data Analysis.
A program is used to process measurement data. The program has three main functions:
(1) Graphic outputs of strength profiles of infrared radiation,
(2) Identifying any abnormal strength of radiation caused by sponcom, and
(3) Determining the position and temperature of the spontaneous combustion by the inverse calculation of heat conduction based on the
heat conduction mechanism of coal strata.

17. Thermal Remote Sensing and Infra-Red Techniques
Merits of the Infrared Detection Technique:
 It is remote and requires no direct contact to detect spontaneous
combustion of coal.
 Maximum detection depth of 10 m in a coal pillar.
 90% accuracy for detecting the location of a sponcom.
 It can detect a coal sponcom with temperature at 130º C and above.
 Suitable for detecting “hot spots” in coal pillars and areas adjacent
to roadways.

18. Smell Sensor & Thermal Survey
This invention not only detect heating by smell like a human nose but also
measure the degree of smell. It makes use of piezoelectricity to calculate
the amount of odorant present on the mine atmosphere.
What is piezoelectricity?
Piezoelectricity is the electric charge that accumulates in certain solid
materials in response to applied mechanical stress. The word
piezoelectricity means electricity resulting from pressure.
Working :
 The sensor component employs synthetic bilateral membrane like
human lipid membrane.
 For quantifying the odorants a piezoelectric crystal device that can oscillate several million per second is used.
 Upon absorbing the odorants the weight of the membrane increases and the frequency of the oscillator is changed.
 The magnitude of frequency changes an electrical signal which enables measurement of frequency.
Structure of Smell Sensor

19. Thermal Survey :
The thermal survey can be categorized as :
1. Direct Method
2. Indirect Method
The direct measuring instruments operate making use of following principles:
 Expansion of confined volume of materials e.g. Hg in glass type maximum thermometers, bimetallic strips.
 Melting point of suitable material fire alarms operated by relays with fusible plugs (made of alloys/agents of
suitable melting points).
 Thermoelectric effect e.g. thermocouple type sensors commonly marketed.
 Transducer of different types continuously measuring temperature differential.
Smell Sensor & Thermal Survey

20. Colloid Injection Technique
What is a colloid?
A colloid is a substance microscopically dispersed throughout another substance. A colloid is a
solution that has particles ranging between 1 and 1000 nanometres in diameter, yet are still able
to remain evenly distributed throughout the solution.
Colloids developed for the control of spontaneous combustion can be broadly divided into three
categories :
 Gels,
 Large -molecule colloids,
 Compound colloids.

21. Colloid Injection Technique
Water solidification
Cooling effect due to two
processes: Gelatinization
and Vaporization
Block air leakage paths
Control of formation time of
gelatinization
Thermally stable
Low content
High Elasticity
Low Viscosity
Low cost
Better control of
spontaneous combustion.
HIGH MECHANICAL STRENGTHLARGE -MOLECULE COLLOIDSGELS
SPECIAL PROPERTIES COLLOIDS :

22. Colloid Injection Technique
Two systems have been developed for the colloid injection
technique for sponcom control:
 An underground based system suitable for controlling
small-scale spontaneous combustion.
 A surface-based method suitable for controlling large-
scale spontaneous combustion.
The main equipment used in the underground-based
system includes
i. A movable colloid mixer and
ii. pumping station.
An underground-based system for colloid injection
Required materials are fed into the station and mixed to make the colloid and then pumped into the area
of sponcom via pipelines.

23. Colloid Injection Technique
 To control large-scale sponcom, a surface-based
system should be used. A surface-based mixer blends
base materials with water.
 A pipeline is then used to deliver colloids from surface
to underground, the pipeline is connected to a
number of borehole drilled from underground
workings into the area(s) of sponcom.
 A small mixer and pumping station located
underground is used to mix water with the additive
for fast gelatinization and pump the mix into the
pipeline. Figure shows the flow chart of the system.
The system is capable of delivering 30-100 m³/h of
colloids into sponcom spots. A surface-based system for colloid injection
A surface-based method for Large scale
spontaneous combustion.

24. Colloid Injection Technique
Merits of the Colloid Injection Technique:
 Speedy control of sponcom. For a small-scale e sponcom in a
coal pillar it may take only a few hours to control, even for a
large -scale sponcom in goaf it may take a couple of days at
maximum.
 Colloid can be solidified in fragmented coal, resulting in the
blockage of leakage passes and hence stopping poisonous
gases flowing out from the passes. At high temperatures a
colloid gives off a very small amount of water steam (unlike
water injection technique) and therefore there is no
possibility of explosion of water gas and no risk of injuries
resulted from high temperature water steam.
 To date there has been is no reoccurrence of sponcom in an
area treated with colloid.

25. Any Questions???

26. Thank You !!!