Production-associated risk factors of seismicity in the Kiirunavaara mine

Abstract

When it comes to deep mining, the geomechanical risks of production planning decisions are amplified due to the high-loading environment and typical deep rock mass behaviour such as seismic activity, ground falls, spalling, strainbursting, and rockbursting. Assessing how production decisions influence hazards is an important aspect of risk assessment. A preliminary analysis of the historic production at the Luossavaara-Kiirunavaara Aktiebolag (LKAB) Kiirunavaara mine indicated a significant likelihood of ore/host rock remnants after production blasting in some volumes of the mine. These remnants are caused by a combination of drill fan geometry, orebody geometry, safety regulations minimising the likelihood for drill breakthrough, and typical limitations of blasting practices. Numerical stress analysis modelling was used for a selected volume of the mine critical to production to evaluate the effect of possible geometric realisations of the production remnants. A qualitative risk assessment of the production remnants was completed, with focus on results that indicated seismically active volumes. The understanding gained from this work is important to the mine’s future production planning, as it gives insight into factors that increase the risk of seismicity.