Ammosov North-Eastern Federal University, Yakutsk, Russia:

B. N. Zarovnyaev, Director of Mining Institute, Doctor of Engineering Sciences, mine_academy@mail.ru
G. V. Shubin, Head of a Chair, Candidate of Engineering Sciences

Chersky Institute of Mining of the North, Siberian Branch, Russian Academy of Sciences, Yakutsk, Russia:
A. S. Kurilko, Deputy Director of Scientific Work, Doctor of Engineering Sciences
Yu. A. Khokholov, Leading Researcher

Majority of Russian and foreign open pit mines will reach ultimate depth and will transit to mining with underground methods in the nearest decades. To protect underground mines from aerodynamic and geomechanical disturbance from the side of an open pit, the structure of underground mining flow charts is introduced with a special element — safety ore-and-rock cushion that is to subside gradually, next to ore extraction from upper levels of underground mines using systems with caving. While in service, the cushion is subjected to various eff ects from above, from the side of an open pit void (low temperature and snow in winter, raining in summer, saline infl ows the year round) and from below, from the side of an underground mine (moist mine air). As a consequence, complex thermal processes run in the body of the cushion; and it is required to study comprehensively these processes to avoid complete adfreezing of the cushion and loss of required flowability (mobility). A mathematical model is developed to forecast temperature and moisture content of safety cushion during ore extraction in pit bottom under conditions of permafrost. The model takes into account initial temperature and moisture content of rocks, grain composition, stratifi cation, porosity of broken ore, temperature and moisture content of mine and open air, depression. The authors report the forecast results for temperature and moisture content of safety cushion. It is shown that ice accretion rate under seepage of atmospheric precipitation and snowmelt is 2–3 times higher at the top of the cushion than at its bottom. The forecast results allow predicting potential adfreezing of broken ore and, thus, decision-making on rational conditions of ore discharge.

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