Sergo Ordzhonikidze Russian State Geological Prospecting Institute, Moscow, Russia:

K. S. Malskiy, Dean at the Faculty of Oil&Gas Geology and Geophysics, Associate Professor, Candidate of Engineering Sciences, malskiyks@mgri.ru
Yu. A. Borovkov, Professor, Doctor of Engineering Sciences
A. A. Nikitin, Professor, Doctor of Physico-Mathematical Sciences
A. V. Petrov, Professor, Doctor of Physico-Mathe matical Sciences

The analysis of theoretical approaches and the results of experimental studies into frozen shows the technical and economic feasibility of using frozen backfill material in underground mining in the conditions of negative temperatures of rock mass. At the same time, the disadvantages of such schemes are identified. These include low constructability of frozen backfills in comparison with cemented backfills, high labor content and difficult delivery and storage of unfrozen water in winter. These disadvantages determine the relatively high cost of backfilling but the main factor affecting mining performance is the long time of ice freezing. However, despite the obvious negative experience of froze backfill, in some cases it is possible to obtain good results comparable to the cemented backfilling. The most affordable refrigerants in natural conditions of the permafrost zone include cold air and naturally chilled gangue rocks after heading and stoping. On the other hand, backfilling with these refrigerants takes a long time and lags behind the rate of formation of the mined out space in case of highly mechanized stoping. Therefore, the task of accelerating the formation of backfill elements using the most affordable refrigerants is crucial, because this is the only way to ensure high productivity of mineral extraction at minimal loss and dilution of valuable ore. The process of the frozen backfill formation is analyzed as a function of such key influences as composition of backfill materials, as well as temperature of mine air, gangue and water. The conditions of frozen backfilling of the required strength are formulated.

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