Geology and Resource

The criteria for block caving resource models differ from those for other mining methods. Because mixing processes are integral to cave mechanics, any caving resource model should include the grade contained in rock surrounding the ore body. Being a non-selective method, caving may require less detailed spacing for resource classification than selective methods do.

Geotechnical Characterization

Geotechnical characterization for block caving must address stability, instability, and fragmentation Unlike in geotechnical evaluations for more traditional mining methods, the impact of rock block defects other than open joints has to be understood. It is also essential that rock weathering characteristics are evaluated.

Downstream Effects on Processing

Block cave mining can significantly impact downstream processing and, in particular, the performance of crushing and grinding circuits. As caving progresses, variations in ore hardness and fragmentation size can reveal bottlenecks in circuits designed for “average” conditions. To handle feed property variations, a flexible process flowsheet should be matched with an unselective mass mining method like block caving.

Caving Mechanics

Caveability and fragmentation are key components of caving mechanics. In addition to addressing critical hydraulic radius, caving rates, and cave propagation, impact of large scale structures has to be also understood. For realistic estimates of cave behaviour the in situ stress magnitude and stress direction must be also known.

Mining Method Selection

Not all large-tonnage ore bodies are suitable for caving methods. Factors such as geological context, ore body geometry and inclination, surrounding country rock quality, orebody strength, overlaying strata, and surface water conditions must be taken into consideration when selecting an appropriate mining method, including any caving variant.

Mining Strategy and Mine Design

Mining strategy must be determined before mine layout and not the other way around. In addition, the success of a cave mine design in one situation does not guarantee its success in another. Access, material handling, and infrastructure such as ventilation must be tailored to each mine’s unique conditions.

Equipment Selection and Productivities

To satisfy goals for mine productivity, ventilation, and safety, it is important to make sound equipment selection and sizing decisions. Equipment should be selected to suit optimal underground openings, rather than vice versa. While options for mine automation could be considered during the early stages of mining, the expectations of what could be achieved should be realistic.

Caving Simulation and Production Scheduling

Caving simulation and production scheduling software such as Footprint Finder, PCBC, PCSLC, MineSIM should be used throughout the mining cycle, rather than only after mine design. Simulation can aid mining method selection, trade-off studies, project optimization, forecasting, and reconciliation.

Monitoring and Instrumentation

Unlike with most other mining methods, knowledge of cave mining processes is limited and instrumentation often provides the only clear indication of what is happening inside the cave. Instrumentation such as microseismic monitoring as well as in-hole monitoring, production level deformation monitoring, and direct surface subsidence measurements are being used.