Mining Institute, Kola Science Center, Russian Academy of Sciences, Apatity, Russia:

S. V. Lukichev, Director, Doctor of Engineering Sciences
I. E. Semenova, Divisional Manager, Candidate of Engineering Sciences, innas@goi.kolasc.net.ru
O. V. Belogorodtsev, Researcher

Kirovsk Branch Apatit, Kirovsk, Russia:

V. S. Onuprienko, Chief Engineer

The annual production capacity of the Kirovsk mine in the last decade has almost doubled and reached 18.5 million tons. But this is not the limit—the perspective plan for Apatit provides for its increase to 25 million tons, including 23.5 million tons of underground mining. In this regard, it becomes necessary to involve ore reserves located in more complicated mining conditions, which requires an integrated approach to solving problems in order to achieve the wanted rates of mining development. For the scientific substantiation of excavation and integrated solution of engineering problems, numerical simulation methods and modern software tools were used, allowing obtaining full-fledged digital models of underground and open geotechnologies. This approach is widely used in world practice. The Mining Institute, KSC RAS created original software products adaptable to specific tasks and conditions, namely:
– mining and geological information software MINEFRAME;
– software Sigma GT for 3-D finite element modelling of rock mass stress–strain state with regard to the main geological and geotechnical factors.
The alternate modeling of lower level mining in the Kirovsk mine and stress–strain analysis provided engineering solutions towards the increased production capacity from 18.5 to 25 million tons per year under conditions of reduced ore bodies thickness and the need to excavate some of reserves in the transition zones between open and underground mining, as well as near the thick and geodynamically active structure of the Saamsky fault. The optimal location of cuts and transition zones, as well as the transit order for the Saamsky fault were found. The parameters of the sublevel caving with advanced relaxation zone arranged in the hanging wall were determined. The value of the optimal angle of the stoping front relative to its advance is determined to ensure safety of mining. The proposed recommendations will be used in the mining project for the lower levels in the Kirovsk mine. The principles formulated for the safe mining during intensified ore extraction are also relevant in other cases of deep-level mining in hard rock masses subjected to high tectonic stresses.

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