Determination of Underground Mineable Reserve with Regard to Metal Price Uncertainty and Sustainable Development

Mineable reserve determination is one of the important parameters in economic profitability and the safety of underground mining production. The fluctuations in the metal prices will lead to a change in the cut-off grade, and as a result, the mine layout and mineable reserve will change. On the other hand, changing the underground mine layouts will also change the economic, social and environmental impacts (sustainable development parameters). Therefore, ignoring metal price uncertainty lead to a non-optimal design. The aim of this paper is the determination of underground mineable reserve regarding metal price uncertainty and sustainable development. Metal price uncertainty is simulated with Monte Carlo technique and the most important sustainable development indicators are entered in the cut-off grade formula. In this way, four types of cut-off grades were defined. Based on these cut-offs four types of mine layouts are obtained. Basic, simulated, green and sustainable mine layout. Basic Mine layout is that obtained by normal design, simulated mine layout considers just metal price uncertainty, green mine layout considers metal price uncertainty and environmental criteria and sustainable mine layout considers metal price uncertainty and environmental and social criteria. Results from the use of this methodology in a hypothetical gold mine show that the mineable reserve in sustainable mine layout is 17 percent greater than the basic mine layout. Regarding the result, with this methodology in addition to consideration of metal price uncertainty and sustainable development criteria, the more mineable reserve will be achieved. For future research, in addition to using other price simulation methods; it is suggested that other indicators of sustainable development be included in determining the underground mine layout.

Decrease in coal losses during mining of contiguous seams in the near-bottom part at Vorkuta deposit

The problem of formation of extended zones with high rock pressure (HRP) from safety pillars at the boundaries of extraction pillars formed due to the mine layout of complex geometry is considered at the example of JSC Vorkutaugol mines. A detailed analysis of the remaining reserves of the near-bottom part of the deposit was carried out to estimate losses and the impact of HRP zones from the Chetvertyi protective seam to mining operations on the Troinoi upper seam along with the possibilities for the reduction of sizes of HRP zones at the account of expanding the underworked space. Due to research on the near-bottom part of the Vorkuta deposit, within the framework of the accepted layout, a zone at the Komsomolskaya mine and two zones at the Zapolyarnaya-2 mine were singled out, at which losses at the boundaries of the extraction pillars amount up to 13-22 % of the total resources of the mine field. The high volume of losses in these pillars indicates the relevance of research on the priority extraction impact of protective seams on the efficiency and safety of mining operations in the working area of underworked and HRP zones. Based on the analysis of foreign and Russian experience in the pillar cleaning-up at the boundaries of working areas and the methodical guidelines and instructions, a technological scheme was developed that allows increasing the coal mining recovery factor in the near-bottom part of the Vorkuta deposit from 0.75 to 0.9 without fundamental changing of the ventilation and transport networks and also without purchasing any additional mining equipment. The conducted economic calculations confirmed the effectiveness of implementing the new technological scheme for cleaning-up reserves at the boundaries of extraction districts. The economic effect is from 0.079 to1.381 billion rubles of additional profit from coaxial extraction pillars, depending on the mining and geological conditions and the size of the pillars.