Coal Mining Techniques and Problems
Read the Information Sheet and complete the table:
1.
Question
Describe open cast mining
Answer
3.
What are the main
disadvantages of
underground mining?
4.
What is washout?
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5.
What is seam splitting?
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Surface
Overburden is rocks removed to depth of coal seam – can be
expensive to remove
Spoil heaps are overburden near edge of pit
Restoration by backfill of pit
Pit dug at angle – weak rocks = shallower slope; faults and
joints weaken rock and need improvement
Underground
Main shaft dug from surface
Ventilation shaft required
Coalface between two roadways
Rotating machine cuts coal from face, which falls onto
conveyor belt
Held up by steel supports (chocks)
Mining is backwards – mined-out area allowed to collapse
Faults displace seam
Meet hard rock = machine damage
Fault = weakness = permeability and flooding
Horizontal so if dipping seams = can’t do
Change in sedimentation as peat eroded away by river,
leaving sand and gravels instead of coal seam
Splits into several uneconomical seams
6.
How does the water table
affect mining?
Why is methane gas a
problem?
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Flooding
Expensive to pump out water
Builds up and can be explosive
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2.
7.
Describe longwall mining.
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Opencast Mining
Advantages
Disadvantages
Underground Mining
Advantages
Disadvantages
Cheap – low tech
Can’t reach deep seams
Reach deeper seams than open
Expensive – high tech
Flexible if problems
Overburden storage instability
Mine under sea or areas where
open pits would be eyesores
Inflexible if problems
Mine steeply dip seam
Groundwater supply disruption
Less polluting
Only mine horizontal seams
Economically mine thinner
seams
Eyesore
Waste backfilled into mine
Water issues – expensive to
pump out
Gas dispersed to air
Dust and noise (baffle)
Roof collapse/cave ins
Roof collapse less problematic
Less safe
Safer
Spoil tips unstable
Water easily dealt with
Coal Mining Techniques and Problems
Read the Information Sheet and complete the table:
1.
Question
Describe open cast mining
2.
Describe longwall mining.
3.
What are the main
disadvantages of
underground mining?
4.
What is washout?
5.
What is seam splitting?
6.
How does the water table
affect mining?
7.
Why is methane gas a
problem?
Opencast Mining
Advantages
Disadvantages
Answer
Underground Mining
Advantages
Disadvantages