Vol 52, No 5 (2016)

The article focuses on seismic monitoring of causes of landslides. Such studies are of great importance in open pit mining in permafrost rocks. Extensive mining-induced impact in combination with natural thawing of permafrost as a consequence of the planet warming may end in catastrophe. The authors describe a procedure for plotting velocity profiles of seismic waves along slopes in the presence of extremely contrast discontinuities conditioned by permafrost rocks. The presented approach enables studying slip surfaces of landslides and detecting potential failure zones where wave velocities are lower due to extensive jointing. The processed field data obtained in the area near Chagan-Uzun settlement in Kosh-Agach district of the Republic of Altai are reported.

The article describes a proved method to calculate stress state of support and surrounding rock mass, considering roof and wall rocks displacement until the contact with the support. The method is based on the use of the intact rock mass stiffness matrix formed prior to mining. Modeling of drivage using the method of initial stresses allows splitting the problem into two subproblems: the first subproblem is on mechanical state of rock mass during roof and wall rocks displacement, the second subproblem describes joint deformation of roof rock, walls rocks and support. The cases of stress calculation for rocks and support, considering support installation conditions, are described. The stress behavior depending on the value of roof and wall rocks displacement until the contact with the support is determined. The features of the method application in case of greatly different mechanical characteristics of rocks and support are discussed.

Based on the tests of packings of calibrated glass balls with a diameter of 1 mm, it is shown that multiple point impacts improve waveguide characteristics of the medium—conducting paths composed of force “chains” emerge in the test material. The further quasi-static alternating shears change the packing of particles, break the chains and reduce conduction. If continued onward, the multiple impulsive loading results in recovery of the “chains” and in better conduction of the paths.

The author reports test data on disc-shaped specimens of rocks and model media with a hole drilled through the center of the specimens loaded along the diameter. The test data processing uses non-local fracture criteria. The calculated destructive forces are compared with the measured destructive loads. Based on the tests of specimens with the central through holes, the tensile strength algorithm is presented.

Gravity-induced horizontal stress in rocks is assessed in the framework of physical simulation using a flexible thin-walled cylinder. Compression of loose geo-materials changes diameter of the cylinder, which allows estimating horizontal stress. The observed dependences with various compacted geo-materials are then theoretically approximated based on characteristics of porosity, rock deformation modulus and Poisson’s ratio. The obtained relations are applicable to estimation of gravity-induced horizontal stress in an intact rock mass.

Based on the developed procedure, experimental regularities are obtained for the formation of submicron particles under rock failure. The experiments involved explosion load on rock specimens and their uniaxial compression with the concurrent control over size and amount of particles until failure using laser spectrometry. It is found that most of all particles are formed in the size grade of a few microns irrespective of the kind of loading. Dynamics of the formation of particles depends on structural characteristics of specimens and on the value of the compression stress. The authors emphasize the promising nature of the experimental results usable both in the environmental monitoring and for disaster prediction in the course of mining.

Under discussion is the experimental estimate of an actual power variation range of pneumatic hammer with a ring-type elastic valve arranged in exhaust unit of back-drive cell in order to lock mechanically this cell until exhaust stroke at various values of the hammer travel. The variation ranges of the valve channel cross-section are found to ensure sustained operation of the pneumatic hammer and the minimized air flow rate irrespective of the hammer weight and position (vertical or horizontal) and the ratio of the hammer power-stroke to the hammer power-stroke cell diameter.

The authors present the schematic circuit of the new-generation compression/vacuum–impact machine (CVIM) and its operation using an adjustable magnetic lock, which allows varying the machine power performance and extends the machine capacities in mining, construction and seismic exploration. The operational cycle of CVIM is tested. The authors determine technical parameters of the machine and mechanisms of interaction between the lock, striking unit, air reserve tank and compressed air source. CVIM unit blow energy is estimated at different space positions of the machine. The field trial has assisted in denoting ways of further improvement of the machine.

The authors develop a version of a compound technology with consolidating backfilling and caving for thick flat body of polymetals. Numerical evaluation shows that the technology with the cover caving above consolidating backfill ensures higher safety of mining.

The authors give basic design procedures for two-level rock bolt support in underground mining in permafrost regions. The use of rockbolting in combination with heat insulation on a test site in Dzhebariki-Khaya Coal Mine is studied.

Under discussion is the particle and bubble interaction in froth flotation. Water flow from an interlayer between a particle and a gas bubble under effect of hydrophobic component of wedging pressure is studied. It is assumed for a mineral to be extracted, that electrostatic interaction slightly influences the particle and bubble contingence and the liquid interlayer thinning. For this reason, particular attention is given to the effect exerted by mineral particle surface hydrophobicity on water flow rate from the interlayer. It is found that water flow rate under influence of hydrophobic component of wedging pressure is less than water flow rate under physical adsorption of a reagent. The authors hypothesize that hydrophobization creates areas on the mineral particle surface, where the reagent species active relative to gas–water interface attach in accordance with the polarity equalizing rule. Physically adsorbed reagent species pull out water from the interlayer after the interlayer rupture and, thus, remove the kinetic constraint of the particle–bubble attachment.

Laser diffraction analysis and dynamic light scattering method are used to study highly dispersed particles generated during milling of lead–zinc ore (Gorevsky deposit), rich sulfide and impregnated copper–nickel ore (Norilsk and Kingash deposits), as well as Gorevsky Pb concentrate and Sorsky deposit Cu and Mo concentrates. Zeta-potentials of particles are measured in clarified (colloid) solution above precipitation; surface composition of ores and their fine sizes is analyzed using X-ray photoelectron spectroscopy. The highest yield of particles under 5 μm size grade (to 3 total percent) was observed in case of Kingash ore; moreover, zeta-potential of these particles was positive at pH 9.5 and surface compositions of precipitation and colloid particles were nearly the same. Comparatively high content of ultra dispersed fractions was observed in case of Gorevsky ore and Pb concentrate. Clarified solutions contained mostly aggregates of nano-size particles, first of all, Si and Mg minerals, with the hydrodynamic diameter of 500–1200 nm, which shows little changes with time. Sulfide component of hydrosols contains many nano-size particles of minerals that better resist oxidation (sphalerite, molybdenite, pentlandite, chalcopyrite) and, in particular, can transfer metals within the ambient medium.

Integrated development of Volkov copper–iron–vanadium deposit is impossible without heap leaching of copper from old oxidized and complex ore stock pile. The current condition of the stock pile imposes risks of pollution on the Laya River water and on the topmost aquifer groundwater. The natural protection barrier between the groundwater and the old oxidized and mixed ore stock pile is rather good. Permeability of the upper layer of the stock pile, determined by the standard procedure in accordance with the construction norms and regulations, is classified with ambiguousness. For final decision-making after geological engineering survey, permeability characteristics of the upper layer were analyzed using different−concentration sulfuric acid solutions to simulate heap leaching conditions.

The entropy analysis is used to study composition of trade effluents in the Kemerovo Region. Clusters of pollutants: aniline, fats, oils, oil products, phenols, synthetic surfactants, silicon, fluorine, chromium, cyanides, aluminium, vanadium, iron, magnesium, copper, nickel, lead, zinc, nitrates, nitrites, ammonia nitrogen are detected in organic and metal-bearing water solutions. The evolution of population of the pollutants in surface water bodies in 2008–2013 is illustrated. It is found that water quality of most water bodies in the discussed mining region is beyond standard.

The down-the-hole unbalance vibration exciter with the pneumatic drive is designed to treat face zone in the seismic frequency range. The modular-type source consists of a vibration generator with the automated stepped static moment variation, a hold-down unit and an in-built pneumatic percussive device to advance the facility in uncased holes. The article gives pilot test data on R&D model of the vibration exciter, and amplitude–frequency characteristic and spectral content of the excited signal.