Extraction of Crown Pillar in Kittilä
Extraction of the crown pillar separating the open pit from the underground mining was to be conducted as a part of the transition from open pit to underground mining at the Kittilä mine.
Itasca carried out a study of crown pillar mining on the stability of the open pit and underground infrastructure. A numerical model including the open pit, mined underground stopes, and large-scale geological structures and shear zones was created to study stress redistribution, yielding and deformation. The model was set up in 3DEC using the CAD-software Rhino together with the mesh generator KUBRIX Geo.
The results showed that mining could be conducted wihtout adverse effects on the pit walls and existing infrastructure. Recommendations were also given regarding excavation sequencing and backfill of the crown pillar stopes.