Unit
- Resource classification: Mineral resources are categorized as inferred, indicated, or measured based on geological sampling density and confidence levels. This classification guides feasibility studies and investment decisions for mining projects.
- Ore deposit types: Deposits form through magmatic, hydrothermal, sedimentary, and metamorphic processes. Each type dictates the spatial geometry and grade distribution that influence extraction method selection.
- Grade and tonnage: Ore grade refers to the concentration of valuable mineral within the host rock, typically expressed as a percentage or grams per tonne. Tonnage represents the total quantity of ore available for extraction.
- Cut-off grade: The minimum grade at which material can be economically mined and processed. Below this threshold, material is considered waste and must be separated during mining operations.
- Strip ratio: The ratio of waste material removed to ore extracted. A high strip ratio increases costs and may favor underground methods over open pit approaches.
- Mineral deposit geometry: Shape, dip, thickness, and continuity of the ore body influence access methods. Flat-lying deposits suit longwall mining, while steep veins require cut-and-fill techniques.
- Geotechnical factors: Rock strength, joint patterns, groundwater conditions, and in-situ stresses determine excavation stability and support requirements. These factors are critical for both surface and underground operations.
- Mineral rights and tenure: Legal ownership of mineral resources varies by jurisdiction and includes exploration licenses, mining leases, and surface rights. Securing tenure is a prerequisite for any extraction project.
- Mining method classification: Extraction methods are broadly divided into surface mining (open pit, quarry, strip mining) and underground mining (room-and-pillar, cut-and-fill, sublevel stoping). Selection depends on depth, geometry, ground conditions, and economic factors such as cut-off grade and strip ratio.
- Open pit mining design: Used for near-surface, large-tonnage deposits. Key parameters include bench height (typically 10-15 m), overall pit slope angle (40-55°), and haul road width. Proper design minimizes stripping volume and ensures stable slopes throughout the mine life.
- Underground mining methods: Chosen when stripping ratio or depth makes surface mining uneconomic. Methods include unsupported (longwall, sublevel caving) and supported (cut-and-fill, shrinkage stoping). Selection depends on rock mass rating, ore body dip, and required production rate.
- Mine planning and scheduling: Determines the sequence of extraction, equipment fleet requirements, and waste management using block models and optimization software. Long-term plans guide capital investment, while short-term schedules ensure consistent mill feed and operational efficiency.
- Dewatering and water management: Groundwater inflows into pits or underground workings must be controlled via pumping wells, drainage galleries, or grouting. Effective dewatering prevents slope instability, reduces blasting costs, and maintains safe working conditions below the water table.
- Ore handling and processing: Extracted ore undergoes crushing, grinding, and beneficiation (flotation, leaching, gravity separation) to concentrate valuable minerals. The processing route is tailored to mineralogy, with comminution energy and reagent consumption directly affecting operating costs.
Safety Consideration
Hazard: Inadequate knowledge of ground conditions can lead to slope failures in open pits or roof collapses in underground mines. Early geotechnical assessments are vital.
Mitigation: Conduct thorough geotechnical investigations before designing extraction methods. Use empirical charts and numerical modeling to evaluate stability. Establish monitoring systems for ground movement.
Quick Revision
- Mineral resources are classified by confidence level into inferred, indicated, and measured categories.
- Ore deposits form through multiple geological processes that dictate geometry and grade distribution.
- Cut-off grade and strip ratio are economic thresholds that influence method selection.
- Geotechnical factors and mineral rights are foundational for safe, legal extraction.