“Yakutniproalmaz” Institute (Mirnyy, Russia):

Drozdov A. V., Head of Laboratory, Candidate of Geological and Mineralogical Sciences, e-mail: DrozdovAV@alrosa.ru

Kramskov N. P., Chief Researcher, Doctor of Engineering Sciences, e-mail: KramskovNP@alrosa.ru

Sorochenko M. K., Junior Researcher, e-mail: SorochenkoMK@alrosa.ru

“ALROSA” JSC (Mirnyy, Russia):

Doynikov Yu. A., Vice President

“Udachnyy” mine is referred to the type of dangerous, because of the gas and oil ingresses. Meanwhile, any forms of gas ingresses (including even dynamic ones) are possible to be found in the stripped rock and ore massifs. The deposit gas constituent comprises the complicated gas mixtures of aerial, chemical, metamorphic, magmatic, and radiogenic origin with three basic variety types of state: free, sorbed and dissolved. The sorbed gases make the greatest problem, because they are contained in separate pores and caverns, which are not directly related with each other, but during the massif destruction, they release and go over to the free state. The carried out investigations identified the gas composition components, which include methane, heavy hydrocarbons, hydrogen, nitrogen, carbon dioxide, helium, argon and unsaturated hydrocarbons. Distribution of gas constituent in adjoining rocks and in kimberlite bodies has a complicated character. The composition, scales and intensity of gas ingress depend, in the first place, on the material composition of rocks, structural-tectonic situation in one or another part of the deposit and close to it, as well as on other nature factors. The close interrelation between gas- and dead oil (bitumen) saturation of rocks was determined for the adjoining sedimentary strata, which explains their genetic relationship. In order to avoid the possible emergencies, connected with the stripping of high-permeability and gas-saturated zones, a complex of measures was worked out, and directed at the degasation of ore bodies and adjoining rocks. There was proposed a number of recommendations on the gas safety providing, including the development of gas saturated intervals with phase stages and decreased charges for drilling and blasting operations. These recommendations also include the following methods of massif gas recovery increase:
-drilling of prolonged (200–300 m) exploration and degassing boreholes;
-advance dewatering for the removal of dissolved gases;
-induced fracture stripping by method of shock blasting;
-vibroseismic impact on rock and ore massifs.
Later on, it is necessary to continue the perfection of technical solutions, aimed at the decreasing of gas dangerous factors, which have an influence on the underground mining of the largest diamond deposit, and on the development of efficient degasation methods of stripped rock massifs with the creation of safe conditions for underground mining.

This research work was held with the financial support of the Ministry of Education and Science of Russian Federation, within the project No. 2010-218-01-001 “Creation of complex innovation environmentally safe technology of extraction and processing of diamondiferous ores in the Far North”, which is being held with the participation of North-Eastern Federal University named after M. K. Ammosov and “ALROSA” JSC.

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