Lecture Overview

  • Introduction
  • Pit Geometry
    • Interaction deposit geometry
  • Design and management
  • Overall process
    • Interaction of distinct operations
  • Machinery – Drill Rigs, Loaders, Excavators etc.
  • General appraisal
  •  History
    • From ancient times to now
  •  Classifications
    • By operation size
    • By material
    • By level of mechanization

Operation Size

  • Huge operations
    • 50 Mio t and more
  • Big operations
    • 10 Miot
  • Standard operations
    • 1-10 Mio t, incl.quarries
  • Small operations
    • < 0.1 Mio t and much smaller

Operation Dimensions

  • Horizontal
    • up to few kilometers in horizontal extension (length – width)
    • several square kilometers in size
  • Vertical
    • up to 600m in depth
    • up to 300m in height

Material

  • Distinction by
    • Hard rock mining
    • Alluvial mining(dredging)
    • Coal mining
    • Dimension stones
  • Due to…
    • Characteristic operations – procedures – shapes

Mechanization

Aspects of Open Pit Mining

  • Stability of steepness of wall
    • Important economic factor
    • Geomachenical considerations
  • Efficiency
    • Due to high mechanization
    • In particular hauling
  • Quality control
    • Quality, grades, averaging,blending
  • Weather /Climate
    • Direct interaction
    • Temperature (arid to arctic), rain (monsoon), etc.
  • Environment
    • Emission (dust, noise,vibrations)
    • Effects on water (ground water, drainage, ..)
    • Landscape (visibility, reclamation,…)
  • Over burden disposal
    •  Due to high overburden amount
    • Space, stability,transportation
  • After mining
    • Utilization of mining area
    • Reclamation, remediation, rehabilitation
    • Land use, land fill, etc.

Pit geometry

  • Open pit
    • Simple basic geometry
    • Open to the atmosphere
    • Cone-like shape
    • Slope angle by rock characteristics

Pit Slope

Pit Deposit

Benches

  • subdivision of overall slope into
  • Access of men and machinery
  • Dimensions
    • Size of equipment used
    • Efficiency of operations
    • Safety,stability
    • Quality control
  • Working Benches
    • benches where extraction, loading and hauling takesplace
    • design criteria based on operation, incl.safety
  • Safety, residual benches
    • remaining bench-shape on overall pit slope
    • dimensions determined by general slope angle (geomechanics)

Design – pit project

  • Distinction
    • Long term (strategic > 10-20 years)
    • Midterm (1-5 years)
    • Short term (operational, daily -monthly)
  • Goal
    • Optimization – of course
    • Dependent on time scale
      • What can be changed within time period
    • Dependent on knowledge (deposit,market)
  • Project Phase

Pit development

  • Flexibility on pit adjustment
    • Rather low due to the simple basic pit shape
    • Access to certain areas requires usually preceding top-down extraction(pre-strip)
    • Which is time consuming
    • Hence decisions need some preliminary lead time to take effect
  • Required Flexibility
    • Knowledge on deposit (reliability)
    • Characteristics of deposit
    • Market situation
    • Technical situation
  • project design
    • Variation / divergence from assumptions
      • By experience (for adaptations)
      • In advance (starting project)

Summary

  • Approach of optimum of overall process from deposit to market
  • Assessment of uncertainties of
    • Deposit (incl. geomechanics)
    • Technical process,market
  • Pit design based on required flexibility
    • Number of extraction areas, mainly number of working benches
    • Adequate equipment – Drilling Rigs, Loader, Trucks, Curshers etc.

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