2. Content
• Open pit mining
• Advantages & disadvantages of open pit mining
• Underground mining
• Advantages & disadvantages of underground mining
• Khalashpir Coal Mine
3. Open Pit Mining
What is Open Pit Mining method?
Open pit mining is a surface mining technique
of extracting rock or minerals from the earth.
4. Advantages Of Open Pit Mining
Minimum development work need prior to coal production.
Greater safety no danger of explosion or fire. However danger include
landslides on excavation or spoil pile.
Fewer and more simple machinery need for coal production.
Almost all in situ coal may be recovered.
5. Disadvantages Of Open Pit Mining
Large area of land temporarily lost for mining further area needed
for overburden emplacement.
Noise and coal dust pollution in and around mining area.
Need to excavate large volume of overburden to extract coal.
Mining is affected by rigorous climate condition like heavy rain or
snow.
Maximum depth of mining limited by cost of overburdened.
6. Underground Mining
What is Underground Mining method?
Underground mining refers to various
underground mining techniques used to
excavate minerals & rocks.
7. Advantages of Underground Mining
• It allows minerals to be extracted from deep underground
• It doesn't create a mess like open cut or surface mining
• Does not affect the physical environment as much as surface
mining
• It enables the land above the zone of mining to be reclaimed for
other uses
• If it is accessed by horizontal adits, it can mine until the lowest
adit upwards.
• The development and mining can continue so long as economic
exploitation is possible.
8. Disadvantages Of Underground Mining
• Untreated mine water discharge may pollute environment.
• Methane gas explosion, spontaneous combustion root, collapse ,water
flooding pose danger to mine personnel.
• More complex mechanics are required for coal production.
• Need major development work i.e. shaft sinking, tunnel building etc.
• Subsidence at the surface may occur if backfilling is not done.
• Pillars often contain valuable ore that has to be left in situ for safety
measures
• Mining in an underground environment is often inefficient with
economically valuable material inevitably, occasionally, being left in
the stope roof / floor or side walls
9. Comparison between Open pit & Underground Mining
Open Pit Mining Underground Mining
Minimum development work need prior to coal
production.
Need major development work i.e. shaft
sinking, tunnel building etc.
Need to excavate large volume of overburden to
extract coal.
Most excavations apart from entry and tunnel
are made in saleable coal.
Large area of land temporarily lost for mining
further area needed for overburden emplacement.
Only the area around pit-top is visibly disturbed
.Subsidence at the surface will occur if
backfilling is not done.
Noise and coal dust pollution in and around mining
area.
Untreated mine water discharge may pollute
environment.
Greater safety no danger of explosion or fire.
However danger include landslides on excavation or
spoil pile.
Methane gas explosion, spontaneous combustion
root, collapse ,water flooding pose danger to
mine personnel.
Mining is affected by rigorous climate condition like
heavy rain or snow.
Climate do not affect the mining.
Maximum depth of mining limited by cost of
overburdened
Can work coal to grater depth overburden to
coal ratio not critical.
Fewer and more simple machinery need for coal
production.
More complex mechanics are required for coal
production.
Almost all in situ coal may be recovered Less than 60% of the in situ coal commonly
recovered
10. Khalashpir Coal Field
• Khalaspir coalfield is located in pirganj
upazilla of Rangpur district, about 13 km
west of pirganj town. The coal field is
about 35 km to the southeast of
barapukuria coal field.
• It was discovered in 1989 by geological
survey of Bangladesh. The coalfield was
delineated and defined on the basis of the
four drill holes done during 1989-90.
• The coal was encountered at depths
ranging from 257-482 meter below the
surface.
11. Coal Quality
• Khalashpir coal is low sulfur high volatile bituminous to low volatile
bituminous type.
• The sulfur content of the coal range from 0.24 to 3.15% with average
of 0.77% .ash content 7.66 to 50.51% averaging 21.08%, volatile
matter from 2.93 to 30.47 averaging 22.86%.Fixed carbon 32.0 to
80.81%. Moisture content .36-5.99%.
12. Thickness of Coal Seam in Khalashpir
Coal
zone
Area
Average
thickness
(m)
Total
probable
reserve
(million ton)
proved probable
I
2.52
sq. km
12.26
sq. km
16.9
685
II 9.9
III 1.2
IV 6.9
V 2.7
VI 2.6
VII 1.6
VIII 1.3
• The more thickness seam is
I, II and IV. And less coal
seam is III, VIII .
• Khalashpir coal field have 8
(VIII) coal seam
• The proved area is 2.52 sq.
km and probable 12.26 sq.
km and probable reserve is
685 million ton.
13. Mining System In KHALASHPIR
• In that field, coal seams I, II and IV are thickest, thus mining activity has to
be proceeded from, in consequence, I to IV. Over and above that a pre-
requisite option for choosing the appropriate underground mining method is
the thickness of coal seam. Indeed, more than 2m to less than 50m ranged
coal is susceptible for longwall multi-slice mining method, on the other side
room and pillar method requires more than 50m. In khalashpir coal field,
the shallower depth of coal seam is 215.14m thus inclined shaft with an
inclination of roughly 600 has recommended to rendering the proposed
mining activity additionally in perspective of stripping ratio, top coal caving
and backfilling are mandatory to accomplish.
14. References
• M. Badrul Imam Sir, Energy Resources of Bangladesh .
• Wikipedia/khalashpir coal field.
• http://www.academia.edu/khalashpir coal field.
• M.B. Imam, mineral resources of bangladesh. Dhaka, bangladesh:
university press ltd., 1997, 169pp (in bengali).
• http;//www. Advantages and disadvantages of open pit mining
and under ground mining .
