Vol 53, No 4 (2017)

The article reports the results obtained in the trial of elements of the monitoring system for potentially hazardous areas at Korobkovo deposit of the Kursk Magnetic Anomaly. The system is based on the seismic and deformation measurements aimed to estimate and control shear stiffness of potentially hazardous faults. The fault shear stiffness is estimated through the analysis of parameters of seismic waves in the vicinity of a fault. The sources of seismic signals in the trial were explosions carried out at the neighbor surface and underground mines.

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.

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 gasbearing 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.

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 intensity 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 authors have studied the mechanism of 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 methods: 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 changes in the chemical state of atoms on the surface of minerals are mainly connected with the sequential transformation of stages in the process of formation and modification of a functional cover of mineral surface, with variation in a 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.

In terms of sulfide copper–molybdenum ore of Sorsk stockwork deposit (Republic of Khakasia), the authors discuss the option of selective dissociation of minerals. The scope of the discussion embraces the effect of pulsed-discharge treatment on particle-size indexes, structural and chemical properties and floatability of objects of the study. It is shown that the pulse-discharge treatment in a greater degree influences copper sulfides and levels their floatability while surface of molybdenite undergoes minor alteration. The pulse-discharge treatment allows enhancing flotation selectivity in separation of copper sulfides and molybdenite, and promotes removal of hydrophobic molybdenite film from quartz surface, which results in production of high-quality molybdenite concentrates.

When gold occurs in mining waste for a long time, it becomes coated with dense films of hydroxide of iron, manganese, copper and silver sulfides, hydromica powder and clayey particles, which greatly complicate concentration of such gold by gravity. An efficient method to remove such coatings from gold is treatment of waste using chemical reagents based on halogen-containing compounds. The article presents experimental results on extraction of fine gold from tailings of sluice boxes and dredging classifiers using such chemical reagents.

Under consideration is the influence of various crushing techniques on the particle-size distribution and selectivity of dissociation of basic mineral components in the composition of Dalnegorsk complex ore under pretreatment. Distribution of basic elements per size grades is determined in crushing feed and in products of magnetic separation and flotation. Conditions of preparation and separation of disintegration products are described. The authors illustrate the change in the dissociation selectivity criterion in jaw crushing and in disintegration in a press to prepare different-size ore for processing by magnetic separation and flotation.

The article summarizes the results of the long-term research on the anthropomorphic soil in reclaimed and successive areas of the Most Basin in Czech Republic. The main attention is paid to the main dump localities of the Most Basin monitored on the long-term basis. Based on the evaluation of the paedological development of the areas, the presence of contaminants and the development of the vegetation cover, the authors of the article propose optimal management methodology for the areas damaged by mining based on the detailed survey of individual localities within the Most Basin conditions. Emphasis is placed on the methodology of establishing areas left to undergo natural succession.

In terms of Tashtagol Mine, the authors address the issues connected with the configuration and surface of cavities formed by blasts of explosive charges in high-stress rock mass structured as a hierarchy of blocks. Laser scanning of a cavity offers the data on linear and angular characteristics of the cavity surface. The analysis of the surface structure provides details of the rock mass block hierarchy, which essentially influences formation of the roof and sidewalls of the cavity. Individual areas of the cavity surface are described with the help of approximation of measured coordinates of the cavity boundary in the cross sections using the second order curves, including circumferences and ellipses the radius of which are canonically connected with the phenomenon of zonal disintegration of rock mass.