As part of its strategic transformation, Luossavaara-Kiirunavaara AB (LKAB) is currently evaluating an expansion of activities at four of its sites located in northern Sweden, encompassing production rate and depth increases at its existing underground mines, a surface to underground transition, as well as a potential greenfield operation. Ventilation modeling is part of the evaluation process and requires an extensive set of inputs.
This paper details the obtaining and assessment of geothermal gradient and thermal rock properties for each site. These parameters were not previously available yet are essential inputs for ventilation modeling and will influence future ventilation designs.
Geothermal gradients were determined through depth-temperature logging of select boreholes and validated against historical and recent measurements. Core samples extracted during exploration were analyzed using various analytical approaches, with multiple samples for each of the main site-specific lithologies selected.
Results show depth and location-dependent differences between geothermal gradients as well as differences in thermal properties obtained, which are compared to values calculated using modal composition data for a limited set of lithologies. The potential causes of these differences and general implications for ventilation modeling are discussed and lead to recommendations for future thermal parameter studies.
