ALBERT

Description: 〈h3〉Abstract〈/h3〉 〈p〉The results of investigations aimed at solving the topical problem of geodynamic risk assessment in mining of the Khibiny rockburst-hazardous deposits in the Kola Peninsula are presented. The developed procedures and approaches contribute to minimization of geodynamic risks under large-scale mining of close-spaced apatite-nepheline ore deposits. The geomechanical model is designed, which allows analyzing successive development of a system of closely spaced deposits in the Khibiny Massif. Based on the model data on the stress-strain state, the optimal sequence and direction of mining in the conditions of rockburst hazard is determined. The nested structure of the rock mass, direction of the tectonic compression, main radial faults, daylight surface relief and the parameters of the ore bodies are taken into account. The complexing of the predicted stress fields and seismicity improves reliability of detection of higher rockburst hazard zones. The examples of stoping sequence substantiation using a set of in-situ and numerical methods are given. The main lines of development in the geomechanical support of mining and the variants of process solutions toward regional and local unloading of rock mass are shown.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Intersector models are efficient mathematical and modeling tools, which are well studied and widely used in economy. It is contradictory that intersector analysis is neglected in mining, especially since no other field has accepted and implemented the application of the model of operation research as mining did. There are not many satisfactory explanations as to why this is so. In order to explain this dilemma, this paper is directed at the peculiarities and characteristics of the intersector analysis, towards observation of its application in the mining industry on the intersector model of the Mining basin of Kolubara, which operates in the system of the Electric Power Industry of Serbia, and demonstrates the implementation and validation of observations and conclusions.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The test bench and procedure are proposed for investigating intensification of methane release from coal samples under wave field action, which favors increase in degassing rate. The additional equipment is designed for delivering coal cores from mines and taking into account free-released methane volume.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The influence of surface mining on the initiation of large seismic event is considered. The conditions of shearing-type dynamic events are described. A surface mine with the similar parameters as the Bachatsky open pit mine in Kuzbass is adduced as an example for quantifying the mining-induced change in the stress state in the plane of a future rupture as a result of an induced tectonic earthquake nearby a fault plane is quantified. The calculations are performed for different geometrical parameters of the fault zone: the changes are more observable in the zones of gently dipping thrust faulting and less appreciable in the area of steep normal faulting and strike-slip. In case of large surface mines, the zone of positive change in the Coulomb stresses higher than several tenths mega pascals has a considerable dimension and an area markedly larger than the area of nucleation zone of earthquakes of the magnitude 〈em〉M〈/em〉 ≤ 6. In such conditions, even a small variability at the level of first percentage points of the natural stresses can be sufficient for the initiation of seismicity-generating shearing along the high-stress faults. It is found that, as against underground mining, the surface mining activities have no influence on localization of large earthquake sources but can draw the event nearer.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The influence of structural characteristics and interaction parameters of minerals on separation method of lead-bearing complex ore in Russia is analyzed. Based on the studies of deep dissociation of minerals under disintegration using Mineral Liberation Analyzer (MLA), the quantitative distribution of mineral associations in grain-size categories is determined. From the data on mineral dissociation, the series of mineral associations, characteristic of complex ore from some deposits, are defined using milled samples of ore material. It is shown that galena associations with chalcopyrite, fahlore, secondary copper sulphides, sphalerite, pyrite and gangue mostly occur in finely dispersed aggregates with fahlore and, to a lesser degree, with other sulphides. The obtained series of mineral associations make it possible to determine the sequence of dissociation and separation of final-size minerals in the inter-cycle operations during flotation. The primary flotation concentrate contains fahlore, secondary copper sulphides, gold associations, galena and corroded pyrite.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The results of the research and tests in production of beryllium concentrate of the superior and commercial grades as well as the marketable fluorite concentrate from ore and waste of the Ermakovsky deposit are presented. The ore and waste contain a mineral complex which is hard to separate using fat acids and features an increased content of fluorite. Production of the marketable flotation concentrate is based on fixation of calcium in pulp using sodium carbonate, caustic soda and sodium tripolyphosphate. The autoclave-membrane electrolysis technology is developed for the production of marketable beryllium hydroxide from beryllium concentrates. The technology consists of a set of successive operations: dissociation in autoclave, separation of the suspension after the autoclave dissociation, removal of admixtures from the solutions, membrane electrodyalysis of alkaline solutions, hydrolysis of sodium beryllate and separation of beryllium hydroxide. The processing data of the test beryllium concentrates obtained using the autoclave-membrane electrolysis technology are given.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The relevance of the studies into ash and slag from coal combustion in the thermal power sector in Eastern Transbaikalia is governed by the demand for highly efficient and environmentally clean processing technologies aimed at complete utilization of waste. The compositional analysis of the coal-fly ash—ash-and-slag geosystem is given. A special study of processability of ash and slag from combustion of Kharanor, Tataur amd Urtuy coals is carried out, and the main areas of their efficient use in the regional economy are substantiated. The process flow chart is developed for the integrated processing of ash-and-slag waste from thermal power plants in order to obtain marketable products in the form of xenospheres, magnetic fractions, rare and rare earth concentrates, as well as by-products for the building and road construction industries, etc. The proposed complete processing integrates principles of flotation, magnetic and electrostatic separation as well as leaching, and enables considerable reduction in the environmental impact, improvement in performance and increase in investment attractiveness of thermal power plants.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The purposeful formation of man-made deposits is connected with the creation of such conditions under which a waste material acquires preset process properties while stored. This will enable future environmental clean processing of waste. Aiming to determine general mechanisms of formation of process properties in copper-pyrite ore tailings, the comprehensive analysis of mineralogical composition of tailings from three concentration plants processing ore from six large copper-pyrite deposits in the South Ural was performed. The crystal-chemical formulas of the basic ore minerals are studied and systematized. The morphological varieties of ore minerals are identified. It is found that even in case of deposits of the same genetic type, processing regimes and parameters of current mill tailings depend on the initial mineralogical features of waste based on which man-made deposits are formed. These features have influence on the mechanisms and stages of the secondary minerogenesis in the man-made deposits.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Longwall top coal caving mining provides high productivity where thick coal seams exist. The study aims to predict the cavability character of the top coal for deep and thick coal seam in Soma lignite basin located at Western Turkey. Active longwall top coal caving mines are at a depth of 100–400 m and they were used for comparison purposes. New coal mining operations will be initiated in deep sectors of the basin in the future. Future longwall top coal caving operations will be unique under a depth of 700–1200 m with a varied thickness. Several empirical and numerical methods are utilized in the study. Pre-existing empirical approaches lack of essential data and additional numerical modeling is necessary to be employed in order to assess cavability character of the projected new mines. Numerical modeling provides a practical platform for construction of ground response curves. Existing mines and future mining operations can be evaluated and compared by ground reaction curves and a final conclusion about cavability character is reached.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The process of a rigid rough plate shear in a granular medium is considered. The influence of three factors is analyzed: stiffness of loading, weak shocks and air filtration. It is shown that weak shock actions and air filtration, either separately or jointly, can act as a trigger of uncontrolled dynamic release of elastic energy in rock mass.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Based on the differentiation of coal ash content into constituents, the procedure is developed for estimating overall (technological and natural) dilution. The accumulated data base on the Elgin coal deposit (South Yakutia) is described. This data base was used to model coal seams for studying variability of their parameters and properties. The estimated ash contents due to mining operations and connected with the discriminated natural groups of mineral admixtures are presented. Higher variability of the overall ash content and its components across the area and in section of coal seams is shown. The percentage of various thickness steaks inside coal seams in the structure of ash content may reach 14–27% and more. Coal mines insufficiently account for this fact, which leads to incomplete utilization of geological potential of complex-structure deposits. It is emphasized that the resource-saving ash content control should not only be focused on processing efficiency. Based on additional appraisal of mineral reserves, it is possible to gain new capabilities of control at the stages of mine planning and design, actual mining and coal pretreatment.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Airflow reverse is a severe problem in an underground ventilation system. In addition, the airflow stability and safety production can be seriously affected by the problem of air velocity overrun in the roadways. In this study the crucial causes of the ventilation problems in a coal mine case study are analyzed and a solution is proposed through an analytical methodology. Measurements indicate high air resistance in the shaft and low values in the maintenance roadway, generating abnormal airflow directional behaviors. Strategies to solve the ventilation-related problems have been proposed and implemented, verifying normal ventilation conditions.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The method of theoretical analysis, finite element numerical simulation and experimental research were used to explore the damage and the strength degradation law of granite under ultrasonic vibration over time. It is of great significance to improve the effect of rock crushing, and to provide theoretical guidance for the application of ultrasonic vibrators in hard rock drilling and development of ultrasonic vibration rock drilling. The finite element method is used to establish the practical heterogeneous rock model to analyze the law of rock crack propagation in different time periods, and the ultrasonic vibration time threshold is proposed to provide theoretical guidance for the experiment. The porosity and strength of the rock samples are measured by nuclear magnetic resonance and uniaxial compressive strength after vibration. The influence of vibration time on rock damage is analyzed.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The problems of mining in British Columbia (Canada) open pits over three decades under various mining conditions were discussed. The case histories of slope instability with analysis of their features were investigated. The recommendations are given that will benefit present and future pit operations in managing slope stability issues.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Physical processes are initiated in rock mass by long-term induced vibration loads which give rise to triggering factors the neglect of which can result in instability of underground structures. The methodical characteristics of the trigger effect monitoring are described for the specific operating conditions of an underground powerhouse hall of a hydroelectric plant in the Kola Peninsula in Russia.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The application variants of remote metering technologies, such as laser scanning and airborne imaging, are discussed. Based on the international experience gained in photogrammetry, a technique is proposed for surveying using a camera, quadcopter, electronic tacheometer and an appropriate software support. The sources of errors and the requirements imposed on the survey precision in point positioning in the horizontal and in the vertical are determined. The experimental approval of the technique with the assessment of the obtained data accuracy has been carried out in the Sokolovskaya Mine of the Sokolov-Sarbai Mining and Processing Production Association.〈/p〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉A unified mechanism explaining the rotation of a suspension and the azimuthal rotation of a dust structure in the plasma of a vertically oriented gas discharge placed in a longitudinal magnetic field is proposed. Basically, it consists in the action of a magnetic field on the electric current produced by the directed motion of ions in the layer of space charge around the solid bodies placed in a plasma. The derived expressions, which define the dependences of the torque of the magnetomechanical effect acting on the plate and the angular velocity of azimuthal rotation of the dust structure on external plasma parameters, qualitatively correspond to the experimental results.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉The dynamics of the motion of the magnetic moment averaged over an ensemble of nonequilibrium spin-injected electrons in a ferromagnetic junction is considered with allowance for the exchange interaction, as well as the interaction with an external electromagnetic field and a thermostat. The solution of this problem is important for the experimental development of compact terahertz-band radiation sources. The rate of quantum transitions of electrons with opposite spins, which determine the spin relaxation under the interaction with a thermostat, is calculated within the density matrix formalism. It is shown that two spin-relaxation modes can be implemented that correspond to low- and high-Q precession of spin-nonequilibrium injected electrons. The effect of the characteristic features of spin-flip transitions under the relaxation of the magnetic moment on the emission and absorption of photons with-energy corresponding to the energy of effective exchange splitting of spin subbands is discussed.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉We study the stability of a convective flow in a nonuniformly rotating plasma layer in an axially uniform magnetic field. The stationary and oscillating regimes of magnetic convection are considered depending on the angular velocity profile (Rossby number Ro) of the electroconducting medium. Using the Galerkin method for describing the weakly nonlinear stage of evolution of convection, we have obtained a nonlinear dynamic system of Lorentz-type equations. Numerical analysis of these equations has revealed the chaotic behavior of convective flows. The criteria for the emergence of chaotic flows are obtained depending on parameters of convection (Rayleigh number Ra), magnetic field (Chandrasekhar number Q), and rotation (Taylor number Ta) for the Rayleigh (Ro = –1) and Kepler (Ro = –3/4) angular velocity profiles of the medium.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉We consider some general aspects of dependence of magneto-conductivity on a magnetic field in metals having complicated Fermi surfaces. As it is well known, a nontrivial behavior of conductivity in metals in strong magnetic fields is connected usually with appearance of non-closed quasiclassical electron trajectories on the Fermi surface in a magnetic field. The structure of the electron trajectories depends strongly on the direction of the magnetic field and usually the greatest interest is caused by open trajectories that are stable to small rotations of the direction of 〈strong〉B〈/strong〉. The geometry of the corresponding Stability Zones on the angular diagram in the space of directions of 〈strong〉B〈/strong〉 represents a very important characteristic of the electron spectrum in a metal linking the parameters of the spectrum to the experimental data. Here we will consider some very general features inherent in the angular diagrams of metals with Fermi surfaces of the most arbitrary form. In particular, we will show here that any Stability Zone actually has a second boundary, restricting a larger region with a certain behavior of conductivity. Besides that, we shall discuss here general questions of complexity of the angular diagrams for the conductivity and propose a theoretical scheme for dividing the angular diagrams into “simple” and “complex” diagrams. The proposed scheme will in fact also be closely related to behavior of the Hall conductivity in a metal in strong magnetic fields. In conclusion, we will also discuss the relationship of the questions under consideration to the general features of an (abstract) angular diagram describing the behavior of quasiclassical electron trajectories at all energy levels in the conduction band.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉The absorption of ultrashort laser pulses by diatomic CO and HF molecules is studied theoretically. The probability of absorption in the total pulse action time and its dependence on the pulse duration and carrier frequency are calculated. In contrast to atomic systems, where the finite pulse duration effects are noticeable on time scales of the order of femtoseconds, these effects in molecular structures manifest themselves on time scales of the order of picoseconds. In this case, the vibrational–rotational structure of molecular transitions plays a significant role. The results of our calculations of the vibrational–rotational spectra for the absorption of ultrashort laser pulses by diatomic CO and HF molecules are presented. The transition from the nonlinear dependence of the absorption probability for short pulse durations to the standard dependence at long pulse durations corresponding to the transition probabilities per unit time is investigated.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉The photoluminescence of bulky films and heterostructures with HgCdTe quantum wells is studied in the far IR range upon interband optical excitation. Photoluminescence lines are found whose position is independent of temperature, and intensity nonmonotonically changes with increasing temperature. These lines are shown to be related to the radiative recombination of holes by singly ionized mercury vacancies. A drastic increase in the equilibrium recombination of such centers involved in the formation of the photoluminescence signal with the temperature change from 40 to 70 K leads to the nonmonotonic temperature dependence of the photoluminescence intensity.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉The method of masking of a large-radius sphere made of an arbitrary material by a masking coating with a random quasi-zero refractive index is substantiated theoretically and experimentally. In this method of masking, the sphere is first coated with a mirror layer (e.g., high-reflectivity silver) and then with a masking layer with a thickness much smaller than the radius of the sphere. The fraction of the external radiation intensity bending around the sphere at the points of observation near the surface of the sphere and the extinction cross section of the sphere with the masking coating for points of observation far away from the sphere are calculated. It is shown that extinction cross section 〈em〉Q〈/em〉 of the sphere with a masking coating is much smaller than 2〈em〉D〈/em〉, where 〈em〉D〈/em〉 is the geometrical cross section of the sphere; this corresponds to the masking effect for the sphere in the wavelength range of at least 450–1200 nm in the transparency region of the masking coating.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉The volume and the electrical resistivity of glassy selenium (g-Se) are precisely measured at a high hydrostatic pressure up to 9 GPa. The bulk modulus at normal pressure (〈em〉B〈/em〉 = 9.05 ± 0.15 GPa) and its baric derivative (〈span〉 〈span〉\(B_{P}^{'}\)〈/span〉 〈/span〉 = 6.4 ± 0.2) fall on the general concentration dependence of the properties of Se–Ge glasses. The bulk modulus is found to behave substantially nonlinearly in the pressure range 〈em〉P〈/em〉 〈 3 GPa, and this behavior is not related to glass density relaxation (which is absent in this pressure range). The electrical resistivity of g-Se decreases almost exponentially with increasing pressure and reaches 20 Ω cm at 8.75 GPa. The inelastic behavior and weak volume relaxation in g-Se begin at a pressure above 3.5 GPa. Both the volume and the logarithm of electrical resistivity exhibit noticeable (logarithmic in time) relaxation at above 8 GPa. The detected volume hysteresis (1%) and significant (two orders of magnitude) electrical resistivity hysteresis are associated with the pressure-induced structural changes in the glass. They cannot be explained by partial glass crystallization, since no crystalline phase impurity was detected right after experiments. A noticeable (about 1.5%) crystalline phase impurity appears in a sample only after long-term (1 day) storage at a pressure above 8 GPa. Moreover, the crystallization kinetics of g-Se is studied under normal conditions after the action of a high pressure.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉The crystal structure and the magnetic properties of the HTSC cuprates YBa〈sub〉2〈/sub〉Cu〈sub〉3〈/sub〉O〈sub〉6 + δ〈/sub〉, Y〈sub〉1 ‒〈/sub〉 〈sub〉〈em〉x〈/em〉〈/sub〉Ca〈sub〉〈em〉x〈/em〉〈/sub〉Ba〈sub〉2〈/sub〉Cu〈sub〉3〈/sub〉O〈sub〉6 + δ〈/sub〉, and Nd〈sub〉1 +〈/sub〉〈sub〉〈em〉x〈/em〉〈/sub〉Ba〈sub〉2 –〈/sub〉〈sub〉〈em〉x〈/em〉〈/sub〉Cu〈sub〉3〈/sub〉O〈sub〉6 + δ〈/sub〉 (〈em〉x〈/em〉 = 0.2) with the structure of a layered perovskite are studied. The well-known aging effect detected in these HTSC materials during storage under standard conditions, namely, an increase in their critical temperature 〈em〉T〈/em〉〈sub〉〈em〉c〈/em〉〈/sub〉 and a decrease in lattice parameter 〈em〉c〈/em〉 in time, is investigated. Using YBa〈sub〉2〈/sub〉Cu〈sub〉3〈/sub〉O〈sub〉6 + δ〈/sub〉 as an example, we show that the dependence of 〈em〉c〈/em〉 on the oxygen content undergoes the following changes in time: (1) the negative slope of the dependence with respect to axis δ increases and (2) nonlinearity appears and grows in time according to a quadratic law. The first type of changes is explained by an increase in the valence of copper ions, which is accompanied by a decrease in their radius. The second type is explained by the electrostatic interaction of structural CuO〈sub〉2〈/sub〉 planes due to the accumulation of electron holes, which come from CuO〈sub〉δ〈/sub〉 planes, in them. The calculation of the second type of changes in parameter 〈em〉c〈/em〉 in the YBa〈sub〉2〈/sub〉Cu〈sub〉3〈/sub〉O〈sub〉6 + δ〈/sub〉 cuprate exhibits good quantitative agreement with the experimental data. The second-type changes in the Y〈sub〉1 –〈/sub〉〈sub〉〈em〉x〈/em〉〈/sub〉Ca〈sub〉〈em〉x〈/em〉〈/sub〉Ba〈sub〉2〈/sub〉Cu〈sub〉3〈/sub〉O〈sub〉6 + δ〈/sub〉 compound (hole doping of CuO〈sub〉2〈/sub〉 planes) turn out to be identical to those in YBa〈sub〉2〈/sub〉Cu〈sub〉3〈/sub〉O〈sub〉6 + δ〈/sub〉. However, the differently directed (in time) changes in lattice parameter 〈em〉c〈/em〉 in Nd〈sub〉1 +〈/sub〉〈sub〉〈em〉x〈/em〉〈/sub〉Ba〈sub〉2 –〈/sub〉〈sub〉〈em〉x〈/em〉〈/sub〉Cu〈sub〉3〈/sub〉O〈sub〉6 + δ〈/sub〉 indicate that the CuO〈sub〉2〈/sub〉 planes in the neodymium cuprate are doped by electrons at the initial stage of aging. However, when these planes are saturated with holes in time, the type of doping changes from 〈em〉n〈/em〉 to 〈em〉p〈/em〉 without a noticeable change in the crystal structure, which has been considered to be impossible for layered cuprates to date.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉Monte Carlo methods are used to study the anisotropic Ising model with competing interactions in the region of the phase transition from the modulated to the paramagnetic phase. Using histogram analysis of Monte Carlo data and the theory of finite-size scaling, it is shown that the transition from the modulated state to the paramagnetic one is a second-order phase transition. The critical parameters and temperatures of phase transitions in this region are calculated. It is shown that the modulated–paramagnetic phase transition cannot be described within the framework of the known universality classes of critical behavior.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉A dynamic method is used to measure the thermodynamic functions and the electrical resistivity of fluid lead for a wide range of specific volume and pressure. The measurements errors have been reduced to a level comparable to those of stationary methods. It is found that the transition of the fluid from the metallic state to a nonmetallic state occurs when its specific volume increases 2.7 times relative to the normal value. In each individual experiment the transition occurred at almost a constant pressure, and was detected by the change in sign of the isochoric temperature coefficient of resistance determined for the entire series of the experiments. In the pressure range of 0.6–5 GPa, the specific volume at which the metal–nonmetal transition occurs is found to be independent of pressure, and therefore, the transition line is close to an isochore. For the whole range of states of fluid lead investigated here, the speed of sound and the Grüneisen coefficient have been determined.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉Based on a microscopic approach, we have derived equations for the local magnetization dynamics of a spin system coupled by a dipole–dipole interaction in a uniform magnetic field in the continuum approximation. Using the generalized method of multiple scales, we have found the corrections to the Larmor precession frequency of the magnetic moments due to the interparticle interaction, which lead to a broadening of spectral lines and the formation of satellites far from the Larmor frequency. We have derived nonlinear equations for the magnetization amplitude in higher expansion orders, which admit wave and soliton solutions. We have analyzed the influence of the nonsecular part of the dipole–dipole interaction on the stability of solitons and determined the conditions for their existence.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉Two systems of magnetohydrodynamic equations in the shallow water approximation are proposed as a basis for studies in the field of plasma astrophysics: the system of equations with a full allowance for the Coriolis force and the system of equations on the β-plane in which the changes of the Coriolis parameter are linear in coordinate. Both systems of equations take into account such fundamentally important phenomena in plasma astrophysics as the compressibility and external magnetic field effects, increasing significantly the potential for applying these equations to study astrophysical objects. Compressibility in plasma astrophysics is shown to change significantly the dispersion laws for magneto-Poincare, magnetostrophic, and magneto-Rossby waves. The same nonlinear interactions as those in the absence of compressibility have been found to be realized in the case of a compressible rotating plasma. Three-wave equations in the weak nonlinearity approximation, in which the interaction coefficients depend on plasma large-scale compressibility and thermodynamic characteristics, have been derived by the method of multiscale expansions. Expressions for the growth rates of the parametric instabilities of three-wave interactions with large-scale compressibility have been derived.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉A model is presented and the interaction of accelerated electrons with atoms in a thin film “shooting through” Be target is theoretically described. The algorithm is based on the Monte Carlo simulation of the electron motion in the target accompanied by energy losses in elastic and inelastic interactions. The conversion of the electron energy to the radiation energy in the 11.4-nm 〈em〉K〈/em〉〈sub〉α〈/sub〉 line of Be and the emission spectrum are calculated. The maximum conversion efficiency to the solid angle 4π CE = 3.0 × 10〈sup〉–4〈/sup〉 is achieved for the electron energy 〈em〉E〈/em〉〈sub〉〈em〉e〈/em〉〈/sub〉 = 2.0 keV and a 40-nm-thick freely suspended beryllium film. 200-nm and 400-nm-thick films were experimentally investigated. The maximum conversion efficiency to the solid angle 4π for a 200‑nm-thick film and the electron energy 〈em〉E〈/em〉〈sub〉〈em〉e〈/em〉〈/sub〉 = 2.75 keV was CE〈sub〉exp〈/sub〉 = 9.2 × 10〈sup〉–5〈/sup〉, whereas the calculated value was CE〈sub〉calc〈/sub〉 = 2.5 × 10〈sup〉–4〈/sup〉. The observed discrepancy between the theory and experiment is explained in the paper.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉It is shown that two electrons situated in a quantum well near a metallic electrode are attracted to each other due to the Bychkov–Rashba spin–orbit interaction (SOI) and electrostatic image forces. For quite accessible values of the characteristic parameters of the system, the effective attraction due to the SOI dominates over the Coulomb repulsion, and the formation of a bielectron becomes possible. The theory of the effect is especially simple and clear in the case of a quantum wire. The binding energy of the electron pair significantly increases under the application of a gate voltage of appropriate polarity.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉An explicit expression for the energy of interaction between two spherically symmetric particles via the strain field in cubic crystals is obtained with an accuracy up to quadratic terms with respect to the anisotropy parameter 〈em〉d〈/em〉 = 〈em〉c〈/em〉〈sub〉11〈/sub〉 – 〈em〉c〈/em〉〈sub〉12〈/sub〉 – 2〈em〉c〈/em〉〈sub〉44〈/sub〉. The diagrams depicting the regions of attraction and repulsion between particles projected onto the 〈em〉xy〈/em〉 plane are drawn. It is found that at 〈em〉d〈/em〉 〈 0, the attraction regions are formed mostly along the 〈em〉x〈/em〉 and 〈em〉y〈/em〉 axes. At 〈em〉d〈/em〉 〉 0, the directions preferable for the attraction in the linear approximation with respect to the anisotropy parameter 〈em〉d〈/em〉 are diagonals. However, each such direction becomes “split” into two directions if the nonlinear corrections are taken into account. In passing, we reveal the errors and misprints in the earlier papers based on the isotropic medium approximation (〈em〉d〈/em〉 = 0) and on the linear approximation with respect of parameter 〈em〉d〈/em〉.〈/p〉 〈/span〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The undertaken research is aimed to reveal optimal physicochemical conditions for deep conversion of calcium-bearing alumosilicate raw material. An innovative technology of integrated extraction of nano-dispersion amorphous silica, alumina, calcium fluoride and other useful elements has been developed.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉The authors analyze collecting capacity of desorbable species of xanthates. Desorbable species of the reagent are understood as the species capable to transfer from a mineral particle to air bubble, i.e. to gas–liquid interface, at the moment of rupture of an interlayer between these interacting objects. Flotation process performance is evaluated at the presence of a mixed coating resulting from physical and chemical adsorption and in the presence of a chemisorption coating only. The rates of spreading products of interaction between butyl ethyl xanthates and lead nitrate over water surface are found. The spreading rates and collecting capacities of the mentioned reagents are correlated. It is found that an increase in the length of the hydrocarbon fragment increases collecting capacity of a reagent and the rate of spreading of its products on water surface.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Under analysis is on-site extractability of nonferrous and noble metals from tailings by leaching with natural reagents (humus acids, water, lignin). Redistribution of nonferrous and noble metals in a percolation bed made of old tailings in the Norilsk copper–nickel ore field is studied. Kinetics of dissolving of nonferrous and noble metals under capillary ascensional percolation is investigated. It is shown that directional capillary percolation of solutions is applicable to extraction of nonferrous and noble metals under long-term mining waste storage.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Tunneling operations in urban areas are always associated with surface and subsurface ground movement, which may affect the stability of nearby structures and utilities. One of the main issues in the analysis and design of tunnels, is ground movement after the support systems and settlement systems caused by excavation. This paper takes the discrete element calculation software of Universal Distinct Element Code (UDEC) to set three dimensional calculations models to simulate the construction of Esfahan subway tunnel, analyzing the displacement and stress dynamic response during the construction process. The paper also carries out the comparison analysis of the field measurement of the ground movement. The result indicates that the simulation objectively reflected the rules of movement during the construction process. The results show that the tunnels are stable before support system installation and the tunnel induced movement is allowable.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉Gas–water relative permeability (GWRP) is measured in the tests of full-diameter cores. Based on the obtained GWRP 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.〈/p〉

Description: 〈h3〉Abstract〈/h3〉 〈p〉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.〈/p〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉A magnetic resonance method is applied to the investigation of a number of isostructural diamagnetic compounds ABO〈sub〉3〈/sub〉 (A = Sc, In, and Ga) with small additions of Cr〈sup〉3+〈/sup〉 ions (〈em〉S〈/em〉 = 3/2) sufficient to observe single-ion and pair spectra. It is shown that the resonance spectra for isolated Cr〈sup〉3+〈/sup〉 ions can be described to a good accuracy by the ordinary axial spin Hamiltonian for 3〈em〉d〈/em〉 ions in octahedral oxygen environment. The parameters of the spin Hamiltonian are determined for single Cr〈sup〉3+〈/sup〉 ion and Cr〈sup〉3+〈/sup〉–Cr〈sup〉3+〈/sup〉 pair. Lattice distorsions of the parent ABO〈sub〉3〈/sub〉 crystals caused by the Cr〈sup〉3+〈/sup〉 impurities is discussed.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉Recently, the concept of supersonic 〈em〉N〈/em〉-crowdions was offered. In molecular dynamics simulations, they can be excited by initial kick of 〈em〉N〈/em〉 neighboring atoms located in one close-packed atomic row along this row. In the present study, in 2D Morse crystal, we apply initial kick to 〈em〉M〈/em〉 neighboring atoms located in neighboring close-packed atomic rows along these rows. This way, we initiate crowdion clusters called subsonic 〈em〉M〈/em〉-crowdions. It is well known that static 1-crowdion in 2D Morse lattice is unstable; as a result, the interstitial atom leaves the close-packed atomic row and becomes immobile. However, we show that 1-crowdion moving with sufficiently large subsonic velocity remains in the close-packed atomic row. Crowdion clusters with 〈em〉M〈/em〉 equal to or greater than 2 appear to be stable even at rest, with growing 〈em〉M〈/em〉 transforming into prismatic dislocation loops. It is important to note that stable subsonic 〈em〉M〈/em〉-crowdions (〈em〉M〈/em〉 〉 1) remain mobile and they can carry interstitial atoms over long distances.〈/p〉 〈/span〉

Description: 〈span〉 〈h3〉Abstract〈/h3〉 〈p〉Ab initio calculations were used to determine the structure, electronic zone dispersion, partial (atomic and orbital) densities of states, and levels of impurity–vacancy cluster (MV)〈sup〉–〈/sup〉 (M = Si, Ge, Sn) in diamond. Wavefunctions were determined in the density functional theory approximation using hybrid exchange-correlation functional, localized basis set of Gaussians, and a supercell consisting of 192 atoms. Results are compared with data on undoped diamond and with experimental results. The dependence of the direct and indirect energy gap on the cluster type is discussed. Calculations are carried out taking into account the spin–orbit interaction to identify impurity levels in the valence band. The effect of electron–electron interaction on the position of impurity levels is discussed. The dominant contribution of the 〈em〉d〈/em〉 orbitals to the density of states at the impurity level in all clusters is detected.〈/p〉 〈/span〉