Mining methods 1 - AMRE · Content •Massive Mining >35 0 dip: •Sub-level (open) stoping (blast...
Transcript of Mining methods 1 - AMRE · Content •Massive Mining >35 0 dip: •Sub-level (open) stoping (blast...
Content
•Introduction
•Tabular Deposits <350 dip:
•Longwalling
•Scattered
•Caving
•Wide reef
•Backfilling
Content
•Massive Mining >350 dip:
•Sub-level (open) stoping (blast hole stoping)
•Shrinkage stoping
•Cut and fill
•Sub-level caving
•Block caving
•Conclusion
IntroductionIntroduction
Considerations in the Choice of Mining Method
• Geometry of orebody
• Geological complexities
• Geotechnical properties of the country rock and orebody
• Depth below surface of extraction
IntroductionIntroduction
Considerations in the Choice of Mining Method
•Economic viability including:
• infrastructure
• value distribution
• Environmental aspects
• Engineering constraints
• Relevant legislation
Tabular deposits <35Tabular deposits <3500 dipdip
Considerations:
• depth > 2000m
• high grade – total extraction possible although not desirable
• geological complexity
Longwalling
Tabular deposits <35Tabular deposits <3500 dipdip
Advantages:
• Follow behind development
• Can be trackless
• Concentrated stoping
Longwalling
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Longwalling
Disadvantages:
• Inflexibility
• Variable geology
• Highly stressed abutments
Tabular deposits <35Tabular deposits <3500 dipdip
Scattered Mining
Considerations:
• Narrow reef 2-5m
• Depth intermediate
Tabular deposits <35Tabular deposits <3500 dipdip
Scattered Mining
Advantages:
• Advanced knowledge of geological complexities –pre-development
• Flexibility in choice of stopes - value
Tabular deposits <35Tabular deposits <3500 dipdip
Scattered Mining
Disadvantages:
• Less concentrated stoping
• Change in stress of tunnels as over –stoping takes place
• Highly stressed abutments
Tabular deposits <35Tabular deposits <3500 dipdip
Caving
Considerations:
• Application – weaker hangingwall than footwall
• Controlled bulking
Tabular deposits <35Tabular deposits <3500 dipdip
Caving
Advantages:
• Cost effective
• Face stresses lower
Tabular deposits <35Tabular deposits <3500 dipdip
Caving
Disadvantages:
• Back area support compromised typically gullies
• Controlled cave difficult to obtain
Tabular deposits Flat Tabular deposits Flat -- <35<3500 dipdip
Wide Reef – Bord and Pillar, Drift and fill
Considerations:
• Span between pillars
• Fill material availability
• Subsidence
• Geological weaknesses particularly jointing, potholes, triplets, smectites, etc
• Depth relatively shallow
Tabular deposits Flat Tabular deposits Flat -- <35<3500 dipdip
Wide Reef – Bord and Pillar, Drift and fill
Advantages:
• Mechanization
• Total extraction can be achieved
Disadvantages:
• Economies of scale – lower value ore
• Ore oxidation, groundwater control
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Sub-level (Open) Stoping
Considerations:
• Steep dip
• Favourable geotechnical characteristics
• Regular orebody geometry
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Sub-level (Open) Stoping
Advantages:
• Mechanization – drilling carried out in advance of stoping
• Extraction on retreat
Disadvantages:
• Extensive development prior to extraction
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Shrinkage Stoping
Considerations:
• Steep dip
• Favourable geotechnical characteristics
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Shrinkage Stoping
Advantages:
• Mechanization – drilling carried out in advance of stoping
• Only bulk of ore removed after every blast – provide stability for hangingwalls and footwalls
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Shrinkage Stoping
Disadvantages:
• Ore prone to oxidation and hydrolysis
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Cut-and Fill Mining
Considerations:
• Steep dip, thin
• Favourable geotechnical characteristics
• Fill material characteristics
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Cut-and Fill Mining
Advantages:
• Can be used in ore bodies with irregular contours
• Offers more mining selectivity
• Total extraction
• Working platform
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Cut-and Fill Mining
Disadvantages:
• Orebody is above mining – potential for fall-out if orebody not competent
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Sub-level caving
Considerations:
• Easy separation of waste from ore (magnetic)
• Orebody boundaries are vague
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Sub-level caving
Advantages:
• Pre-drilling
• Economies of scale
• Total extraction
• Little support required
Disadvantages:
• Extensive pre-development
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Block caving
Considerations:
• Steep dip or large vertical extension
• Orebody weak –susceptible to breakage
• Subsidence acceptable
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Block caving
Advantages:
• Economies of scale – cost effective
• Total extraction
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Block caving
Disadvantages:
• Extensive pre-development
• Time lag – slow build-up to production
• Hang-ups at drawpoints – costly secondary blasting