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Development
Introduction
Underground Mining DevelopmentDifferent Access to Ore Bed
Mining Cycle
Some Examples
Surface mining Development
Blasting
Explosives
Drift or Tunnel Blasting
Blast Pattern Design
Firing SequenceSmooth Wall Blasting
Supporting
Objective
Material Used and reinforced
Typical rockbolt systems
Wire Mesh
Shotcrete
Steel Set SystemsTimber Support Systems
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Development
Introduction
Mine Development contains the following:
Drilling Large Deposits
Drilling Small Deposits
Development Shafts and Adits Blocking Out Ore
Access
Power
Communications
Site PreparationMine
Mill
Town Site
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Underground Mining Development
(Mechanized Drift or Tunnel Development)
Basic drilling cycle for drill and blast drifting and tunneling:
Surveying and setup
Drilling
Charging
Blasting
Ventilation
Scaling
Mucking
Scaling
Bolting
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Different Access to Ore Bed
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Mining Cycle
1. Roof bolting
2. Undercutting
3. Drilling
4. Blasting
5. Loading
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Some Examples
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Surface Mining Development
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Blasting in Underground Mining
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Eplosives
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Drift or Tunnel Blasting
Divided Drift or Tunnel face into Design Sections
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Blast Pattern Design
Four section cut.
Large diameter center hole
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Blast Pattern Design
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5-hole Burn-Cut
Various Burn-Cuts
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V-Cut
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Firing Sequence
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Firing sequence for a large tunnel round
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Smooth wall Blasting
Applied Explosives Technology For Construction and Mining, Stig Olofsson, 1997
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Ground Support for Drifts and Tunnels
Objective
- to mobilize and enhance the inherent strength of the rock mass so that it becomes self supporting.
Materials used in tunnel support and reinforcement
Rock Bolting
Shotcrete
Steel rib or arch
Rock Bolt + Wire mesh
Rock Bolt + Shotcrete + Wire mesh
Steel arch + Shotcrete
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Typical Rockbolt Systems
The following groups of bolts are considered based on their anchoring technique:
-mechanically anchored rockbolts
-grouted rock- and cablebolts
-friction anchored rockbolts.
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Principles of Rock Bolts
Rock bolts cause compression to the sides of the holes. Compression strengthens the rock.
Rock bolts in a bedded roof cause the layers to act like beams. Tension at the center of the entry is reduced.
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Rock bolts are used for both surface and underground applications.
Rock bolts can be used with other devices to enhance ground support.
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Face Plates
A face plate is designed to distribute the load at the bolt head uniformly into the surrounding rock.
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The JAMA DBU 800 underground drill/bolt machine.
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Dry Mix Shotcrete
The dry shotcrete components are fed into a hopper with continuous agitation.
Compressed air is introduced through a rotating barrel or feed bowl to convey the materials in a continuous
stream through the delivery hose. Water is added to the mix at the nozzle.
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Wet Mix Shotcrete
The wet shotcrete components and the water are mixed (usually in a truck mounted mixer) before delivery into a
positive displacement pumping unit,
which then delivers the mix hydraulically to the nozzle where air is added to project the material onto the rock
surface.
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Shotcrete robots
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Shotcrete robot applying shotcrete in a tunnel opening
i f S
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Mesh Reinforced Shotcrete
Chain link mesh not recommended because shotcrete can not penetrate
Welded wire mesh, firmly attached to the rock surface, provides excellent reinforcement for shotcrete.
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Steel Set Support
Rigid
Yielding
Timber Support Systems
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Timber Support Systems