Rävliden Rock Mechanics Pre-Feasibility Study
Project Background
Exploration between the two closed mines Rävlidmyran and Rävliden has successfully led to more mineralizations being discovered. Initial project work by Boliden has identified longitudinal or transversal sublevel stoping as possible mining methods. Two major lenses are defined: Rävliden Norra (including Fredolage) and Nisse. An existing exploration drift from the old Rävliden mine lead to this area and some test mining has been conducted. A ventilation shaft from the surface has been
drilled to the exploration drift.The purpose of the rock mechanics pre-feasibility study is to provide input to mine planning in terms of rock mechanics design parameters.
Itasca has analyzed possible mining methods, mining sequences, design parameters, location of infrastructure, reinforcement, and backfilling requirements. A geomechanical model was developed based on collected information including geological model, core logging, and core testing data. Rock mass properties for each
domain were determined. Empirical methods were used to evaluate stope dimensions, overbreak and rock support. Analytical methods were used to evaluate fill strength and rock support. Numerical methods were used for evaluation of sill pillar thickness, pillar width, distance between main levels, mining sequence, distance to infrastructure and main gallery, stresses in rill pillars, and pillar widths between stopes.
Results Summary
The project resulted in concrete recommendations for the mine planning, including:
- When to switch between longitudinal and transversal sublevel stoping, depending on ore width and rock domain.
- Dimensions of the stopes, depending on longitudinal or transversal sublevel stoping, rock properties, and supportmeasures.
- Distance between main levels and sill pillar thickness in different rock domains.
- Fill strength.
- Rock support for drifts, ramps, crossings, and longitudinalmining stopes, depending on width.
- Distance between ore and infrastructure, depending on depth and between ore and main gallery.
It was also shown that the mining sequence was not primarily dependent on rock mechanical issues.
