1. Problems Associated with Mining

2. Types of Mining
Surface Mining
Deep Mining
Open Cast
Longwall Retreat
Pillar and Stall
Drift mining / Adit

3. Open Cast / Strip Mining
Dragline Excavator

4. Brainstorm a list of problems associated with open cast mining……….

5. Drift mining / Adit

6. Pillar and Stall

7. Long Wall Retreat

8. Pillar and stall mining
1. Subsidence
Pillar and stall mining
Cracking & collapse of buildings
Cavities open up

9. Sag Subsidence
Pit Subsidence
Most common type (gentle depression)
Bell shaped hole 2 m deep
Spreads over several acres
1m to 30m across
Cause: Pillar Collapse
Cause: Roof collapse

10. 2. Acid Mine Waste Contaminating Groundwater
Mining
Surface area
Groundwater flow
Leaching of mineral deposits
Iron pyrite (“fools gold”)
Abandoned mines
Water Pumping
Water Table
Prolonged water contact
Dissolves
Sulphuric Acid
Leaching
Acidic Mine waste
Iron minerals
Reddish-brown suspension
AFFECTS:
Fish
Irrigation
Industry
Livestock
Drinking water

11. 3. Release of untreated mine waste into rivers
Wheal Jane Tin Mine, Cornwall 1993 – a major spill of mine waste released serious amounts of acid waste into Falmouth Bay.

12. Map: Showing Deep Mines areas with Acid
Mine Waste Risk
INTERACTIVE MAP
Deep Coalfields 1. 2. 3. 4. 5. 6. 7.
Clyde & Ayreshire
Durham / Northumberland
West Cumbria
South Yorkshire
Lancashire and North Wales
Forest of Dean
South Wales

13. 4. Collapse of Mine Waste
Mine waste is disposed of near to the mine site due to its weight & amount.
600, 000 tons / yr
1966
1964
Aberfan, South Wales

14. 4. Collapse of Mine Waste
On steep slopes, overlooking the village, mine waste tipped since 1914.
In 1966, tip No.7 failed killing 147 (116 children) people.
Heavy rainfall
Tip situated on clay
Spring
Hydrogeology disturbed by mining

15. 5. Emission of Hazardous Gases
Methane is explosive, has a noxious smell and contributes to global warming.
Especially coal mining gives off methane as CH4 is produced during the
Coalification process when plant material (CHONS) was broken down over millions of years.
Mining process – fractures coal – increasing its permeability – releasing GAS!
Mining is also a pathway for the colourless, odourless and carcinogenic
Radon Gas (produced by radioactive decay deep within earth)!

16. 6. Flooding of Mines
Mining below water table requires pumping which causes local disruption of the water table.
East Durham coalfield – 36 billion litres of water pumped from mine system each year.

17. Flooding of Mines
Mining below water table requires pumping.

18. 7. Rock Fall / Landslides
Quarries / opencast mines have steep open faces
Liable to collapse / rockfall
Need careful management:
Soft rocks e.g. clay – Re-graded to a stable angle and drained!
Hard rocks e.g. granite or limestones – Stability analysis to identify weaker areas. Then regrade as well as using cliff stabilization techniques e.g. bolting, mesh curtains and fences to catch boulders