Methane Emission Control at the High-Productive Longwall Panels of the Yalevsky Coal Mine

The analysis of the experience of methane emission control at the V. D. Yalevsky mine (Kuznetsk coal basin, Russia) during the series of shallow gassy coal seams mining with the high productive longwall was performed. The analysis of the efficiency of gob degassing by the vertical wells and isolated methane removal by gas-suction fans is performed. The efficiency of reducing the distance between ventilation crosscuts between entries is shown. It is also shown that the problems of providing the longwall high productivity in conditions of increasing the natural gas content in the coal seams are associated with gas emission from the extracted coal seam and the lack of effective methods for its early and preliminary degassing. Recommendations for using advanced mining of close-up coal seams as an effective method of degassing of rock mass within the zone of influence of undermining and overmining are given.

RISK REDUCTION ESTIMATION FOR UNDERGROUND MINING OF GAS-CONTAINED COAL SEAMS WHILE USING THE HYDRAULIC FRACTURING

In the paper, influence of hydraulic fracturing parameters on filtration resistance of system of parallel holes during preliminary degassing of coal seam loaded with strata pressure is considered. Results of comparative analysis of degassing rates of coal seam while using holes without hydraulic fracturing and holes with non-directed or plural interval hydraulic fracturing of various orientation are represented. Estimation of influence of fracturing of different types on risk reduction of underground mining of gas-contained coal seams is given. Obtained results allow to estimate perspective of application of present modifications of hydraulic fracturing technology at coal mines.

FACTORS AFFECTING SURVIVAL OF LYOPHILIZED FUNGAL SPORES AND CELLS

Spores of Alternaria, Aspergillus, Fusarium, Gliocladium, Penicillium, and Pestalotia, budding vegetative cells of Ustilago, and uredospores of Puccinia graminis, P. helianthi, and Melampsora lini were lyophilized using several techniques and various conditions. The best percentage survival of the lyophilized spores and cells was obtained when the initial freezing of the spore suspensions was just low enough to keep the suspension solid until evaporative freezing conditions were reached. Freezing to very low temperatures was unnecessary. Conditions permitting fast warming of the frozen suspension resulted in increased survival. A preliminary degassing treatment greatly enhanced percentage germination, as did the conditioning of the spores in a moist atmosphere immediately after the opening of the tubes for revival of the organisms.