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  • Created by: lucy
  • Created on: 18-02-13 14:59
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  • Mining
    • Opencast coal mining
      • Quarries or "open pits"
        • Sides are dug at an angle and stepped
          • Increase stability and prevent collapse
          • Rock Type
            • Weak, incompetant rocks like clay
              • Shallow slope angles
          • Structures
            • Faults and joints
              • Weaken the rock
                • Rock bolts Wire netting Shotcrete Rock drains
          • Weathering
            • Heavily weathered rock
              • Weaker
                • Shallow slope angles
    • Underground coal mining
      • Longwall mining
        • Shaft is dug from the surface, two roadways are driven out, shearer rotates to and fro the coalface, coal falls on conveyer belt, transported to shaft
          • Roof is held up by hydraulic steel on chocks
            • When coal is sliced, chock moves into new space
        • Problems
          • Faults displacing coal seam
            • 1 or 2 m can disrupt production
              • Damage shearer
          • Folds and steep dips
            • Longwall mining takes place horizontally
              • Coal seams cannot dip at an angle greater than 5 degrees
          • Washouts
            • river channel switching on the delta top
              • Coal seam is lost as the peat is eroded away by the river
                • In peats place is now conglomeratesand sanstones
          • Seam splitting
            • 1 thick coal seam splits into several thinner, uneconomic seams
              • Result of different rates of subsidence in different parts of the delta
          • Methane gas
            • Flammable -> danger of explosions
    • Aberfan 1966
      • Long term -> Pore water pressure on saturated ground
        • Trigger -> Heavy rain two days before
          • Unconcolidated soil on top of town slid down mountain
      • 144 deaths


Sam Cockman

One improvement that could be added to the types of underground mining is the pillar and stall method. 

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