Zhironkin S.(Department of Trade and Marketing, Siberian Federal University, 79 Svobodny Av, Krasnoyarsk, 660041, Russian Federation, Department of Open Pit Mining, T.F. Gorbachev Kuzbass State Technical University, 28 Vesennya St., Kemerovo, 650000, Russian Federation, School of Core Engineering Education, National Research Tomsk Polytechnic University, 30 Lenina St., Tomsk, 634050, Russian Federation)
Rybár R.(Faculty of Mining, Ecology, Process Technologies and Geotechnology, Institute of Earth Sources, Technical University of Košice, Letná 9, Kosice, 042 00, Slovakia)