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The authors study the influence of physicochemical parameters on methane adsorption capacity of coal and offer the analytical method for the methane adsorption capacity for three-phased condition of methane. It is found that in the depth interval to 300 m below surface, methane adsorption capacity measured in lab can exceed natural gas content of coal obtained from geological exploration data by 30%, and the change in the thermodynamic condition of coal-methane system brings irreversible physicochemical consequences in terms of the altered ratios of physical states of the main components. There is no linear connection between natural gas content of a coal bed and its methane adsorption capacity with respect to occurrence depth. The application of Big Data in treatment and interpretation of large data flows is described. The theoretical data predicted using the proposed method and the experimental data on methane content of Kuzbass coal agree.

In focus of the article is minimization of aftereffects of the large-scale accident connected with the flooding of Berezniki Potash Mine in the Perm Krai. The authors construct a synthesized geomechanical model of the flooded mine to show the mining conditions, the process of salt rock dissolution and the elastoplastic behavior of deformation and failure of undermined rock mass in time. Approaches to analyzing intensity of degeneration of load-bearing elements of the open stoping system as a consequence of salt rock dissolving are proposed. The obtained estimates are the parametric framework for prediction of the ground surface deformation using 3D mathematical modeling. The geomechanical calculation results are used in the managerial decision-making on safety of the industrial and civil infrastructure within the hazardous territory.

Gas-water relative permeability (GWP) is measured in the tests of full-diameter cores. Based on the obtained GWP curves, the standard normalized curves are plotted for three types of carbonate reservoirs: matrix pore, fracture and solution pore. The corresponding gas and water two-phase flow model was deduced by considering stress sensitivity and non-Darcy effect, and the IPR curve calculation and analysis of gas wells of the three types were carried out. Based on huge gap between the matrix and fracture permeability, the phenomenon of gas drive water mainly exists in the cracks. So the conventional gas-water relative permeability of fractured gas reservoirs was modified. The research will lay the foundation for the application of gas reservoir engineering calculation with the production and application of numerical simulation technology to make dynamic forecast.

The integrated study of coal is performed using methods of optical and electron paramagnetic resonances, infrared spectroscopy and Raman spectroscopy. It is found that gas content of coal is governed by the rank of coal and its material constitution as well as by the coal bed structure at the macro-, micro- and nano-levels which interwork. It is discovered that the size and amount of bubbles, of paleo-origin presumably, and the content of coalbed methane are related. The influence of each scale level of the coal bed structure on the gas content is revealed. The authors illustrate benefits of the integrated study of gas-bearing coal with the physical methods that complement one the other at different levels of coal structure.

The authors solve the problem on forces required to change drilling path of air hammers in soil. Soil mass is assumed a rigid-plastic medium with the Mohr-Coulomb yield, and the air hammer deviator is considered as a nondeformable body. The problem is solved in two stages: introduction of the deviator in soil and travel of the air hammer in soil with the rear deviated at a certain angle. The loads applied to the rear, the forces and the moment required to changing the path of an air hammer in soil are calculated.

The substantiated dimensionless criterion of jamming characterizes relationship between the temperature of the contact links of spiroid gearing and the load-bearing capacity of an oil film. Based on the review of the existing tribotechnical systems used in scoring resistance testing, a physical model of spiroid gearing is selected. The test data obtained on a rolling-and-disc scheme of a friction assembly are presented. The relations between the friction coefficient in the spiroid gearing and the unit load are determined for the steel-steel material couples in a range of slip velocities and temperatures. A design procedure for spiroid gearing with respect to jamming is proposed.

Under study is a production system composed of a power motor, compressor, pneumatic percussive machine and a treated medium. Based on the generalized theoretical and experimental data, the author relates productiveness of pneumatic percussive machines, energy intake of rock breakage in the uplands with the rare atmosphere and elevation of the machine work site above sea level. The obtained results offer a reason-why approach to selection of the pneumatic percussive machine parameters for operation in the uplands.

The authors describe a technical approach to validating efficient regimes and process flow charts for draglines in open pit mining in permafrost zone; the approach integrates modeling data on temperature conditions of permafrost treated by blasting, geometrical parameters of a dragline face and interaction of work cycle time and face rock temperature in different seasons. It is shown that a dragline has the appreciably reduced productivity in slice-by-slice handling of broken-rock disintegration having negative temperature.

The article presents a procedure to select loading and transportation machines for an open pit complex ore mine. The choice of a shovel-dump truck production system is validated using a statistical testing method (Monte Carlo technique). Stop-watch readings allowed relating the productivity of the production system, degree of ore fragmentation and content of oversizes; the soundness of the choice of the production system based on the revealed criterion was proved. Using the law of the Palm flows, the authors determine the number and sequence of dump trucks for loading in a one-server system.

The authors have studied the mechanism of the controlled modification of composition, structure, chemistry, physicochemical and process properties of columbite, tantalite, zircon and feldspar at the meso-, micro- and nanoscales after nonthermal treatment by high-voltage nanosecond electromagnetic pulses. The studies used the methods of X-ray photoelectron spectroscopy, scanning electron and atomic force microscopy, potentiometric titration, electromigration chromatography, Kelvin probe force microscopy, microhardness metering and assessment of hydrophobic behavior and flotation activity of the minerals. It is found that the change in the chemical state of atoms on the surface of the minerals is mainly connected with the sequential transformation of stages in the process of formation and modification of the functional cover of a mineral surface, with the variation in the ratio of different type hydroxyl groups on the surface of columbite, zircon and feldspar, which conditions contrast physicochemical properties of rare metal minerals and improves selectivity of their separation by flotation.