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Optimizing parameters of stopes and pillars for the Zhdanov deposit mining

The Zhdanov deposit occurs in the Pechenga area of the Murmansk Region [1–3] and holds one of Russia’s largest reserves of copper and nickel. Minerals are extracted by Severny Mine of the Kola Mining and Metallurgical Company. The mining project embraces 6 ore bodies: South-West, West, Central, East, SouthEast and South [4]. The South ore body occurs in the south-east of the Zhdanov deposit, is tabular and composed of mostly ordinary disseminated ore. The ore body is from 7 to 20 m thick, and its dip angle varies from 70 to 75 [5]. One of the accepted mining systems for the Zhdanov deposit is sublevel caving combined with stopes and pillars [6]. Within a level 60 m high, ore is extracted from stopes with temporal rib and level pillars. Inside a stope, the reserves are caved by sublevels with a height from 15 to 30 m [7]. Stability of the pillars and enclosing rock mass is ensured by efficient span of stopes and dimensions of pillars [8–11]. Intensive and deeper level mining results in worsening of geological and geotechnical conditions in the Zhdanov deposit. Thus, it is of concern to analyze stress state of rocks and to assess meticulously parameters of stable stopes and pillars.