National Mineral Resources University (University of Mines) (Saint-Petersburg, Russia):

Galkin A. F., Professor, Doctor of Engineering Sciences, e-mail: afgalkin@mail.ru
Naumov A. A., Postgraduate

In recent 10–15 years, revitalization has involved gold and other mineral mining in hard-to-reach places of the North, with underground operations and rotation method, without fixed settlements and appropriate infrastructure constructed. This being the case, the wide use of high-performance mining machines with independent (diesel) drive requires large fresh air amount to be fed in a mine to thin down harmful exhaust and create gas-safe working conditions. The air volume fed in some mines reaches 150–200 m³/s. Heating of huge air amount in cold season up to 6–7 months long demands for high energy input and creation of special energy-generating facilities to service air heaters. For this reason, it is often that, in prejudice of comfortable working conditions, fresh air at outside temperature is fed in underground mines. This increases risk of illness with common cold in winter whereas in warm season this causes thawing out of frozen rocks, which results in their reduced stability, and it becomes necessary to set additional support in roadways within the positive temperature area [1, 2] that can spread for several kilometers along the ventilation route. This article reviews the current problems in the field of roadway support in mines of the North, connected with increase of air volume to be fed for mine ventilation and operation in natural thermal conditions. In warm season, this results in reduced stability of rocks. Aiming at higher stability of roadways, it is suggested to use dry-spray light concrete lining. Successful application of this lining in mines of Norilsk and South Yakutia is described. The method of assessing economic effect of thermal-protective coating in mine roadways is offered. The method is based on comparison of expenditures connected with the assigned thermal resistance lining made of light concrete and common shotcrete. The basic formulas for the comparative calculations are given. The plotted nomogram allows on-the-fly definition of the effective use range of light concrete depending on cost of heat-insulating filler.

1. Dyadkin Yu. D. Osnovy gornoy teplofiziki (Basis of mine thermal physics). Moscow : Nedra, 1968, 256 p.
2. Skuba V. N. Issledovanie ustoychivosti gornykh vyrabotok v usloviyakh mnogoletney merzloty (Research of excavations’ stability in permafrost conditions). Novosibirsk : Nauka, 1974, 118 p.
3. Galkin A. F. Teplovoy rezhim podzemnykh sooruzheniy Severa (Thermal mode of underground facilities of North). Novosibirsk : Nauka, 2000, 304 p.
4. Gendler S. G. Zapiski Gornogo instituta – Proceedings of Mining University, 2006, Vol. 17, No. 1, pp. 129–136.
5. Shuvalov Yu. V. Regulirovanie teplovogo rezhima shakht i rudnikov Severa (Regulations of thermal mode of Northern shafts and mines). Leningrad : Leningrad State University, 1988, 196 p.