Institute of Mining, Metallurgy and Chemical Technologies, National Polytechnic University of Armenia, Yerevan, Armenia

A. G. Oganesyan, Doctor of Engineering Sciences, Professor, armen.hovhannisyan@politechnic.am
A. T. Bagdasaryan, Acting Head of Department, Candidate of Engineering Sciences, Associate Professor

RSM Armenia International Center for Sustainable Resource Management, Yerevan, Armenia
S. V. Mamyan, President of Non-Governmental Organization, Candidate of Engineering Sciences

One of the copper–molybdenum deposits, earlier operated in Armenia, represents a stockwork. At the present time, the deposit is subjected to fundamental re-appraisal for the purpose of its commercial development. Two methods of mining of the deposit were discussed: open pit mining and hybrid (open pit/underground) mining. In the second variant of mining, optimization and justification of a technology reduces mainly to solving economic issues—determination of optimal boundaries between the open pit and underground operations. The optimality criterion was assumed to be the maximum profit over the whole period of the deposit development. The optimal open pit depth was determined based on the condition of equality of the limiting and economic stripping ratios. The economic stripping ratio was determined as a ratio of the difference between the horizontal area of the open pit on ground surface and the horizontal area of the stockwork within the open pit limits to the horizontal area of the stockwork within the open pit limits. The optimal scenario of mining the test copper–molybdenum deposit assumes the use of the hybrid open pit/underground method, with the expedient open pit operations to the level of 1990 m, and ore reserves beyond the ultimate pit limit to be extracted using the underground mining method. The optimized ultimate pit limit in the hybrid mining technology, owing to sublevel caving of ore reserves beyond the ultimate pit limit, makes it possible to lower the average stripping ratio by 27.2 %. This leads to a decrease in the total cost of mining and processing by 17.5 % per 1 t of ore and, finally, to an increase in the economic efficiency by 22.8 %The comparison of the limiting and economic stripping ratios shows that the optimal depth of the open pit is confined by a level at the absolute elevation of 1990 m. In this case, the decrease of the total cost of mining and processing by 17.5 % per 1 t of ore leads to the increased economic efficiency by 22.8 %.

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