Navoi Mining and Metallurgical Combinat, Navoi, Uzbekistan:

Yu. D. Norov, Head of Industrial Engineering and Innovation Department, Professor, Doctor of Engineering Sciences, yud.norov@ngmk.uz

Tashkent State Technical University, Tashkent, Uzbekistan:
U. F. Nasirov, Dean of the Faculty of Geologic Engineering and Mining, Doctor of Engineering Sciences
Sh. A. Ochilov, Senior Lecturer

At the present time, all large open pit mines in the world predominantly tend towards benching at increased height. This approach enables better technical and economic performance of deep open pit mines, less number of haulage and mining horizons, higher slope of highwall, reduced stripping ratio and, finally, smaller volume of stripping. The continuous improvement of drilling and blasting methods is aimed at quality fragmentation of rocks in open pit mines with high benches. Among the practiced methods, it is most frequently recommended to use parallel close-spaced blasting. Efficiency of this method is explained by the fact that in the direct vicinity of such blastholes, at a distance of their half-spacing, cylindrical stress waves start to interact and generate a plane front. As a result, rock mass is largely saturated with blast energy, and fragmentation in the remote zones is intensified due to the increased stresses. At the Navoi Mining and Metallurgical Combinat, applicability of parallel close-spaced blasting at high benches of Muruntau open pit mine was studied. The blast pattern and sizes of explosive charges were calculated with respect to the physical and mechanical properties of rocks. Then, an experimental block of a high bench was subjected to large-scale blasting using the conventional and new (studied) methods. The comparison of the blasting outcomes showed that the parallel close-spaced blasting improved rock fragmentation quality along the whole height of the bench, which would increase productiveness of cutting and loading machines.

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