Home – Home – Jornals – Journal of Mining Sciences 2025 number 6

The main problem in solar energy is reducing optical losses due to light reflection from the surface of photovoltaic cells. This paper presents the results of a numerical study of antireflection properties of nanostructured silicon dioxide (SiO₂) coatings deposited on the surface of a solar cell. Two types of porous antireflection coatings are considered: a multilayer assembly of nanospheres and vertical air nanopores embedded in a continuous silicon dioxide layer. The light transmission efficiency is assessed depending on the thickness and structural design of the antireflection coating. It is found that the efficiency of solar energy conversion into electricity can significantly vary across different spectral ranges for the same antireflection coating type. It is shown that a coating made of vertical nanopores in most cases provides more efficient conversion of incident light compared to a porous layer formed by an ordered microassembly of nanospheres. The results are important for the development of more efficient solar cells and can be used to create anti-reflective coatings to improve the overall performance of photovoltaic devices.

Most measurements of aerosol attenuation of the atmosphere are carried out in the visible and near-infrared regions of the spectrum. However, many atmospheric optics tasks require data on the spectral course of aerosol attenuation coefficients in the visible and IR regions, including the atmospheric “transparency window” 8-12 mm. In this regard, models that make it possible to calculate attenuation in the IR region based on measurements in the visible region are of great interest. A one-parameter model of the spectral course of the aerosol attenuation coefficient for the surface layer of the atmosphere is proposed. The input parameter of the model is the aerosol attenuation coefficient at a wavelength of 0.55 mm or the meteorological range of visibility S _m. The model enables one to calculate aerosol attenuation coefficient in the spectral range 0.44-12 mm at meteorological visibility range S _m > 8 km. The model can be used to evaluate the efficiency of different optical systems and to separate aerosol attenuation into submicron and coarse components.

Natural gamma radiation easily penetrates into the cells of a human body and destructively affects all structures causing a wide range of diseases. It also plays an active role in the atmosphere by participating in electrical processes and origination of ions, which affects cloud formation, precipitation, radiation balance, etc. There are very few measurements of the vertical distribution of gamma background over the Russian territory. This paper summarizes the results of aircraft sounding in 2003-2025. Based on the analysis of the long-term data, an average vertical profile of this parameter was calculated, which shows its nonlinear increase with altitude. In the surface air layer, this parameter varied within 0.03-0.25 mSv/h with the average over the period under study being 0.11 mSv/h. At an altitude of 10 km, the gamma background varied in the range 2.18-2.80 mSv/h, and the average was 2.35 mSv/h. The analysis of the latitudinal distribution revealed the belt 60-70° N with high gamma radiation values; the gamma background was lower to the south and north of that belt The data analysis has also revealed a weak annual variation with a maximum in November and a minimum in August, which is not typical for other atmospheric parameters. The results can be useful for choosing the range and uncertainty of developed radiation protection devices and means, as well as for assessing the probability of origination of radiative effects.

Stratospheric polar vortices, which form over the polar regions in late autumn, are large-scale cyclonic formations whose stability in the winter-spring period determines the scale and depth of spring ozone depletion. Using the vortex delineation method based on ERA5 reanalysis data, we studied the features in the vertical dynamics of the Arctic and Antarctic polar vortices in 2020 during their anomalous strengthening, which was accompanied by deep and prolonged ozone depletion in the Arctic and Antarctic. In particular, we examined the synchronicity in temporal changes at different stratospheric levels. The polar vortex breakdown in 2020 was observed from late spring to early summer spreading from top to bottom over 1-2 months. The dynamics of the Arctic polar vortex showed three peaks of activity, spreading from the upper to the lower stratosphere within a month. The dynamics of the Antarctic polar vortex clearly showed one peak of activity spreading from the upper to the lower stratosphere over a period of 2 months. The anomalous duration of the western phase of the quasi-biennial oscillation in the middle stratosphere has been proposed as a possible reason for the unprecedented strengthening of the polar vortices in 2020. The results can be used to assess the risks of increasing ground-level UV-B radiation which is dangerous for the biosphere.

The objective of this study was to determine an optimal radiation wavelength for scanning marine surface from air, which provides minimal radiation absorption, parasitic fluorescence, beam divergence, and scattering in the water column. These parameters depend on the probing laser type used. The research focused on water samples from the Black Sea collected 200 m from the shore immediately before the experiment and water samples stored for one year in light-protected hermetically sealed containers. For both sets of samples, the following were examined: scattering phase function, spectral transmission coefficients, laser beam divergence, particle size distribution of organic matter in the samples, and its effect on fluorescence spectra. Commercial semiconductor lasers with wavelengths of 450, 520, and 660 nm were used. The study shows a 450-nm laser to be optimal for underwater probing tasks since it exhibits the lowest radiation attenuation in the water column (0.5 dB/m), the smallest scattering spot, and minimal fluorescence. Organic particles do not significantly affect hydro-optical properties of seawater in the samples both immediately collected before the experiment and stored for one year. The results can be used in the design of above-water and underwater laser probing systems for marine surface analysis.

To perform accurate atmospheric correction (elimination of the distorting influence of the atmosphere) of satellite images, it is crucial to consider various factors that influence the received signal, including the non-Lambertian surface reflectance (the difference between surface reflection and Lambert's law, according which radiation is equally reflected in all directions and depends only on the irradiance of the surface and the reflectance). High-quality satellite information is important for solving a wide range of problems in monitoring the ground surface, such as forest condition, agricultural productivity, and others. In some algorithms, non-Lambertian reflection is taken into account after solving the problem in the Lambertian reflection approximation. In this case, the assumption is used that the adjacency effect (received radiation reflected from areas of the ground surface adjacent to the observed one and scattered in the atmosphere) is formed only by surfaces with Lambertian reflection. The calculations performed show that at S _M ≥ 6 km, neglect of non-Lambertian reflection produces an error in determining the reflectance of no higher than 20.3%, neglect of non-Lambertian reflection in the formation of adjacency effect and additional illumination results in an error of no more than 12%, and neglect of non-Lambertian reflection in additional illumination, of no more than 1.4%. For more clear situations ( S _M ≥ 6 km), the maximal error for similar models does not exceed 92, 14, and 1.2%, respectively. For solar zenith angles θ_sun ≤ 60° and angles of the optical axis of the receiving system θ_sun ≤ 60°, the errors do not exceed 30, 7.5, and 1%, respectively. The results prove the possibility of considering non-Lambertian reflection after taking into account adjacency effect and additional illumination of the ground surface in the Lambertian reflection approximation.

Interest in understanding the influence of forest ecosystems on the formation of climate parameters continues to grow. This paper examines two approaches to the study of interaction between Siberian forests and the atmosphere. Based on the results of the analysis, it was suggested that the formation of a 4-year cycle in precipitation over forest areas may occur with the participation of tree transpiration. This finding will help us to understand the emergence of similar cyclical patterns in meteorological data from other regions with extensive forest ecosystems. The results may be useful for specialists dealing with problems of biosphere-atmospheric interaction.

A dielectric mirror with high reflectance at a wavelength of 266 nm has been designed for use in ultraviolet lidar systems for ozone concentration monitoring. A multilayer interference coating based on HfO₂ and SiO₂ was manufactured and optimized using experimentally obtained dispersion data. The effect of thermal annealing on the optical properties of the coating was investigated, and a temperature limit was identified, excess of which leads to structural degradation. The results can be used in the design of highly efficient optical elements for ultraviolet differential absorption lidars, as well as other laser systems which require UV dielectric mirrors.

It is known that the formation of vortex structures in a fire negatively impacts the consequences: swirling high-temperature flows of combustion products cause greater destruction than a normal fire. Identifying such vortices is a pressing issue. For this purpose, in the big aerosol chamber of the Institute of Atmospheric Optics SB RAS, two isopropanol flame plumes were simultaneously studied by the thermal imaging method. One of them was a vortex flame obtained by blowing around a stationary container installed on the axis of an ascending swirling air flow, and the other was in a container without blowing. Using the fast Fourier transform (FFT) of the time pulsations of the thermal imaging signal, the power spectra of the pulsation frequencies were calculated. In the calculated spectra, a frequency interval was determined where a significant difference between the mentioned flames was observed. The influence of distance and the averaging effect of the size of the initial region of thermal imaging signal reception on the difference in flame spectra was analyzed.

The article presents the results of a study of the problem of propagation regimes of narrow (millimeter) laser beams in a Kerr-nonlinear turbulent medium, which is a model of evolution of the light inhomogeneities generated at multiple filamentation of high-power laser pulses in the corresponding media. We used methods of diffraction beam tubes and diffraction beams in the theoretical study. It was found that there are three propagation regimes for laser beams with certain parameters in a turbulent medium: self-focusing with generation of a nonlinear focus (beam collapse), self-channeling over a limited distance, and turbulent propagation. An analytical relationship for the square of the beam's effective radius was derived, which is of interest for practical applications in nonlinear atmospheric optics.

This work is devoted to the development and experimental verification of effective methods for compensating for the dynamic atmospheric distortions of a laser beam propagating through a turbulent medium. The paper presents the results of a laboratory experiment on the correction of wavefront distortions of laser radiation propagating along a turbulent path in a pavilion. Turbulence was simulated using a fan heater supplying warm air perpendicular to the beam propagation. Distortion compensation was performed using an adaptive optics system, including a wavefront tilt corrector and a bimorph deformable mirror. The system efficiency was assessed by analyzing the far-field intensity distribution. It is shown that the generated turbulent distortions are spectrally similar to Kolmogorov turbulence with a bandwidth of about 30 Hz. It is found that for effective compensation of wavefront aberrations, the operating frequency of the adaptive optics system should be 20-30 times higher than the turbulence bandwidth. At a system operating frequency of 1 kHz, the beam divergence was reduced to 1.4 of the diffraction limit, and by increasing the frequency to 2 kHz, a beam stabilization accuracy of 5 mrad can be achieved using an FPGA. The results of this work can be used to design high-performance systems related to the propagation of laser radiation in a turbulent medium.

Determining the isotopic shift of vibrational energy levels of molecules is a challenging task in molecular spectroscopy. Detailed knowledge of the vibrational-rotational energy spectrum is necessary, for example, for laser isotope separation. In this paper, a calculation method based on high-order perturbation theory and summation of series by the method of quadratic Padé-Hermite approximants is proposed. The method is applied to determine the isotopic shifts of vibrational energy levels of all stable hydrogen sulfide isotopologues. Calculations were performed using ab initio intramolecular potential function within a simple quartic force field model. To refine the results, corrections were introduced to account for the error in ab initio data. The results of summation of perturbation theory series coincide with the levels determined by the variational method with accuracy of 10^-10-10^-2 cm^-1. The corrections reduced the root-mean-square error in the available experimental level values to 3.5 cm^-1 (0.3%).

This article presents an improved internet-accessible expert system, SLON, for analyzing high-resolution molecular spectra. It was developed in the Laboratory of Molecular Spectroscopy at Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences. The SLON expert system is based on a neural network model capable of making independent decisions when analyzing combination differences formed by groups of molecular transitions from different rotational sublevels of the ground state to the same excited vibrational-rotational state. The set of features by which the neural network distinguishes the correct variant of a combination difference from random realizations has been improved. Restrictions on the size of the analyzed spectrum have been removed. The format of the databases used is now universal and enables expanding the class of molecules under study. A modern multi-platform user interface allows this program to be compiled for Windows and Linux systems. The operating principles, operational experience, and prospects for the development of the created expert system are described.

The problem of aerosol pollution of the atmosphere and associated climate change has become increasingly relevant. Of particular interest are physicochemical properties and structure of atmospheric aerosols. Being an important component of polluted air, aerosols affect various atmospheric processes, the environment, and human health. Analysis of the morphology and composition of aerosol particles allows us to identify the features of their behavior in the atmosphere and determine their origin. This paper studies the composition and morphology of ground-level atmospheric aerosol particles at a year-round monitoring station (Irkutsk) in different seasons of 2024 using scanning electron microscopy and X-ray spectral analysis. The main types of aerosol particles (soot, fly ash, mineral, and biogenic particles) are identified, and their shapes and sizes are determined. It has been established that mineral and biogenic particles predominate in the composition of ground-level atmospheric aerosol in Irkutsk during the warm season, while fly ash and soot particles predominate during the cold season. Brochosomes (fullerene-like structures of biological carbon-containing particles) were detected for the first time in the surface aerosol at the urban Irkutsk station. The results of this study expand our understanding of the morphological properties and composition of individual particles in surface atmospheric aerosol in the urbanized area of the Southern Baikal region.

Atmospheric ions play an important role in the formation of aerosol particles and affect public health. At the same time, measurements of their concentration in Russia are extremely insufficient. To fill the gap, the Fonovaya observatory began monitoring the ion content in July 2019. Analysis of the data obtained showed that from July 2019 to May 2024, the concentrations of both positive and negative aeroions were in the range 220-720 cm^-3. Negative ions have a trend of +7%/year, and positive ions have a trend of -1.2%/year. Ions of both signs have a pronounced annual cycle with a maximum in summer and a minimum in winter. The long-term average daily cycle revealed that the concentrations of ions of both signs change synchronously. The minimum of their concentration is observed in the morning hours and the maximum in the afternoon. The results allow us to clarify the role of ions in atmospheric processes.

Snow cover in the temperate and northern latitudes of Eurasia accumulates atmospheric precipitation during winter. The analysis of the trace element composition of snow cover makes it possible to estimate the level of aerosol pollution of the atmosphere. The estimations are usually made relative to the average background concentrations of elements. However, in a poorly studied region, the selection of background points may be incorrect. We suggest using the upper limit of geochemical baseline variation (ULBL) as a norm. It considers the natural and controlled anthropogenic input of an element and is defined as the sum of the 75-quantile of the distribution of element concentration and the difference between the 75- and 25-quantiles multiplied by 1.5. Using the suggested approach we have detected contamination with Ag, Sn, and Hg in places a priori considered background; a zone of heavy metal contamination at a distance of 9-26 km from the industrial zone; and conventionally "clean" points, where the concentrations of trace elements do not exceed the ULBL. The use of ULBL as a norm enables objective estimation of air pollution over a territory from the results of a single snow survey.

The paper presents the results of lidar measurements of the vertical distribution of optical characteristics of dust aerosol from the Gobi Desert in the free troposphere of Vladivostok. The instrument used is an aerosol-Raman lidar with a cross-polarization channel, which provides vertical profiles of a set of (3β + 2α + δ). High values (δ_а = 0.13÷0.24), typical of submicron dust aerosol particles, are noted in the altitude range 3.00-4.25 km. This altitude range was also characterized by low values of the Ångström parameter (Å = 0.5) and high values of the single scattering albedo ω = 0.98÷0.99. The values of complex refractive index ( m = m _r + im_i ) in the dust layer were characteristic of dust particles: m _r = 1.48÷1.56, m_i = 0.001. The effective radius ( r _eff) varied within 0.2-0.4 μm with a maximum at an altitude of 3.8 km. The particle size distribution function in the dust layer had a well-defined bimodal structure with a slight excess of the coarse mode over the fine one. The modal radii of the fine and coarse fractions r _f = 0.18 μm and r _c = 0.8 μm, respectively.

Stratospheric aerosol, the main component of which is volcanic emissions, is one of the main factors influencing global climate. The role of aerosol formed during wildfires and injected into the stratosphere is clearly underestimated. Taking into account the influence of stratospheric aerosol generated by wildfires into climate models leads to significant uncertainties and highlights the need for an in-depth study of this phenomenon. This paper presents the results of lidar monitoring of stratospheric aerosol dynamics over Tomsk in 2025, with an emphasis on the study of disturbances in the stratospheric aerosol component caused by wildfires. Ground-based lidar sensing in June 2025 detected aerosol layers in the stratosphere over Tomsk at altitudes of 10-17 km. Using trajectory analysis and satellite data on fires, it was shown that the possible source of the observed aerosol layers could be combustion products, including soot injected into the stratosphere by pyrocumulative clouds formed in late May and early June 2025 in the area of severe wildfires covering parts of Canada and the United States. These results are of interest for climate change research in Western Siberia.

The current global warming is caused by an increase in the concentration of greenhouse gases in the atmosphere. Therefore, the estimation of the potential of different ecosystems for the sequestration of atmospheric carbon dioxide on both regional and global scales is relevant. The balance of natural carbon dioxide fluxes throughout the Sverdlovsk region is considered. An integral assessment of the net CO₂ absorbed from the atmosphere by regional ecosystems for the period 2020-2022 is made based on the original NorthFlux machine learning model, where spectral data from the MODIS satellite sensor, meteorological data from retrospective climate analysis, and satellite data on the classification of the underlying surface vegetation are used as input data. Data on anthropogenic CO₂ emissions are taken from the inventory of greenhouse gas emissions in the Sverdlovsk Region. To assess the transboundary transfer of carbon dioxide, we used a balance equation for CO₂ fluxes in the atmospheric column and data on the average annual rate of increase in the CO₂ concentration in the region's atmosphere obtained from ground-based IR Fourier spectroscopy using the Bruker IFS 125M high-resolution spectrometer at the Kourovka Astronomical Observatory for the period 2012-2024. As a result, it was found that the sequestration of atmospheric CO₂ by the ecosystems of the Sverdlovsk region ranges from 10.9 to 15.2%, and its transboundary transfer outside the region to neighboring regions ranges from 72.5 to 76.7% of the annual industrial CO₂ emissions in the region.

The paper proposes a method for analyzing the quality of wind fields from hydrodynamic model forecasts for a specific transport model. This is done using the results of measurements in the Kincaid tracer experiment. The method involves adding normalized random fluctuations to the wind fields up to an altitude of 4 km and analyzing the maximum values of wind speed and direction to obtain accurate results for the transport of pollutants. The measurements are taken from a dense network of specialized stations.

Imaging in the visible spectrum of processes in media transparent only to IR radiation requires the use of active converters of IR radiation into the visible spectrum. In this work, we simulate the transformation of IR radiation into the visible due to competition between transitions in manganese vapor active media. Our approach is based on the spatio-temporal kinetic model of the active medium. We evaluate the coefficient of the transformation for continuous and pulsed modes an input IR signal for a wide range of its power and various pulse repetition frequencies (from 2 to 20 kHz). We show the pulsed mode and pulse repetition frequency lower than the optimal one in terms of the amplified spontaneous emission power to be optimal for this transformation. The measurable transformation factor is higher than 10 for medium-size GDT. Results confirm than the bistatic scheme of a laser monitor on Mn vapor active media can be used to obtain a negative image of processes in a medium transparent for IR radiation, i.e., to make a pulsed narrowband converter of IR signals into visible ones.

The primary challenge in observing small (inconspicuous) space objects with ground-based optical telescopes is the effect of the atmosphere on the passage of radiation from a small (inconspicuous) space object. This paper examines the specifics of long-exposure observations of small space objects by recording short-exposure images of a laser guide star and then summing them in the telescope's focal plane. Correlation analysis is used to investigate the relationship between random displacements of the observed laser guide star image and the predicted position of the small space object. It is shown that a sufficient condition for determining their relative positions is the ratio of the absolute values of the energy centers of gravity of the images as two jointly correlated Gaussian random variables with a Cauchy probability density distribution. Calculation results for monostatic and bistatic laser guide star formation schemes are presented.

The article analyzes efficiency of safety and support of underground excavations at great depths in potassium salt rock masses as a case-study of the Starobin and Petrikov deposits. Various protection technologies are discussed. It is found that owing to formation of block structures and cohesion loss zones nearby the perimeter of mine excavations, the expansion gaps can have both beneficial and adverse influence on excavation stability. The relaxation excavation technology allows a great reduction in the dimensions of limiting state zones in rock mass surrounding mine openings. The model of block movement is proposed, and it is shown that mutual displacements of blocks by more than 1-2 mm in the vicinity of an excavation perimeter can be a cause of the dynamic failure of blocks into mined-out areas. It is recommended to install rock bolting as soon as cohesion loss is detected on sliding surfaces.

Using the mathematical modeling, the author performs the stress-strain analysis of stratified rock mass in the course of mining of close-spaced coal seams with regard to linear change in temperature field with depth. The problem is considered in an incoherent quasistatic formulation: first the temperature field is determined and then the stress-strain assessment is made using the Duhamel-Neumann law. The problem solving used the finite element method. It was assumed that the rock mass layers occur in complete contact. The initial stress state was found on the basis of Dinnik’s hypothesis. The features of the initial stress state, which influence stress redistribution during coal mining, are determined. The variants of close-spaced coal seam mining are discussed, and the related stress state peculiarities are highlighted as compared with mining with no regard to the temperature gradient.

The authors substantiate the method for the qualitative assessment of stresses and permeability parameters characterizing mass transfer in gas-saturated fractured porous coal mass, namely: mass transfer coefficient β, and permeability coefficients of fractured zone and matrix, k₁ and k₂, respectively. The method consists in formulation and solving of a mixed-type inverse problem within the framework of a dual porosity/dual permeability model to estimate the values of β, k₁ and k₂ by the measurement data of the pressure P(t) in a shut-in vertical well. The solvability of the inverse problem is demonstrated on the basis of the analysis of the introduced objective function, and an original algorithm is developed to find a minimum value of the function using additional information on the behavior of P(t). It is found that in the course of time, the function P(t) reaches a stationary value which is independent of the model parameters and is equal to the pressure of gas in an intact seam, which makes it possible to calculate the horizontal stresses outside the influence zone of the well. The proposed method can be used to provide parameters for geomechanical modeling in justification of technologies of pre-mine drainage and methane recovery.

The methane emission parameters are determined in the face areas of the Boldyrev seam, Kirov Mine, and seams 50 and 52, Yalevsky Mine. It is shown that coal of the same seam can have greatly different gas emission rates determined in a few hours after coal detachment from rock mass. The gas emission rate depends on the regularity of microstructure, determined by calculation of information entropy and statistical complexity using digital images of coal surface from an electron microscope. The lower gas emission rate is a feature of coal with a less uniform (more chaotic) microstructure, which is explained by the higher number of cut-off bonds in the aliphatic component of coals, while these bonds are the adsorption centers and prevent faster diffusion of methane.

The authors compare the strength characteristics of rocks, determined by standards GOST 21153.8-88 and ASTM D7012-04. The research involved 7 rock lithotypes (shale, diabase, metasomatic rock, marble, gneiss, quartzite, garnet) and bulk compression, uniaxial compression and indirect tension testing. Mohr’s circles and failure envelopes are plotted for each rock lithotype. The differences between the standards are found in terms of adhesion factors and internal friction angles: ASTM yields higher adhesion factors; internal friction angles vary depending on the rock type. The calculation formula allows predicting the uniaxial compression strength at an error of 10.5%. The failure envelopes are updated using the calculated data. The results highlight the significance of proper selection of a failure envelope plotting procedure in engineering design.

The increase of an undercut height relative to haulage drifts is one of the effective measures aimed to enhance operating safety of the latter. The FEM-based stress-strain change modeling is performed in rock mass during ore block mining in complex geological conditions at different vertical distances between development drifts and stopes. The research reveals an inversely proportional dependence between the undercutting level height relative the haulage level and the total length of operating excavations in the influence zone of stoping. The determined dependence makes it possible to select an optimal height of the undercut level for the benefit of stress control in rock mass and towards minimization of the adverse influence of stresses on mine infrastructure.

The fluid transport analysis in fractured porous rocks requires investigating flow in large fractures and inside porous blocks. This is possible with the flow model with the hereditary-type sources, which allows adding the flow analysis with the pressure difference of fluid in blocks and fractures, which is called a piezometric wave. Its influence on the change in the stress-strain behavior of structural elements in a seam (matrix) is investigated. The theoretical studies validate the possibility of the seam matrix transition to pre- and post-limiting deformation. It is shown that zones of probable pressure-induced disintegration in rocks adjoin the highly permeable zones of seams. Origination of such zones greatly reduces permeability of confined aquifers and efficiency of drainage well. The necessary conditions for these processes to develop and their prevention activities are set forth.

Physical lab-scale simulation finds out that in polydisperse broken ore draw, the medium undergoes structuring which leads to the formation of a consolidated block shaped as a flaring cone. Along the side surfaces of the cone, slide zones originate as layers of small size particles. The angle of the cone generators is governed by the internal friction angle of the medium, which depends on the degree of fragmentation and on the grain size composition. An empirical formula is proposed for calculating the angle of the cone generators. The obtained results make it possible to develop an algorithm and a method for optimizing parameters of structural elements in the caving systems of mining with self-propelled machinery.

The article analyzes interaction of a hydraulic fracture and a permeable crack nearby a void in a uniform medium under triaxial compression. 2D modeling used the finite element method. Possible paths of the created fracture are set as cohesive layers composed of elements which can deform and fail depending on an applied stress. A fluid flow is modeled by additional points with crossflow of fluid from the created fracture into the permeable crack when they intersect. The numerical studies are presented for the nature of the hydraulic fracture-permeable crack interaction depending on the: distance between their interaction point and the void; stress state; strength and internal friction factor of the medium; fluid viscosity. On the basis of the obtained results, for the creation of an antiseepage screen, it is recommended to perform hydraulic fracturing in the vicinity a void at a distance equal to the void radius.

The authors analyze the main approaches to the assessment of the dynamic fracture tendency in rocks on a laboratory scale and report the data of experimental investigation of rock samples. It is shown that the dynamic fracture tendency of rocks depends on their loading conditions, namely, on the stiffness ratio of the loading system and loaded object, on the energy input rate (loading/deformation rate) and on the type of the stress state. It is found that the change in the loading parameters of rock samples during a lab experiment can influence their behavior in fracture; for this reason, in assessment of the dynamic fracture tendency in rocks, it is necessary to consider not a sample, individually, but the whole press-sample system.

The article describes the experimental investigations of stresses and strains in a tubular sample made of an equivalent geomaterial subjected to static compression, torque and multiple weak impacts. The tests show that the sample pre-loaded by the static compression and then additionally loaded by the torque at the shearing stresses of 5-7% of the compression stresses elongates and its diameter reduces and the compressive stresses grow. This process lasts for 120-200 h. The additional loading of the sample by the multiple weak impacts gradually leads to the stress relaxation and to the increase of the axial and circumferencial strains. The process of relaxation is nonmonotonous, with the stress picks and drops. During loading, the elastic energy accumulates and releases in the sample with a period of 80-120 h.

Different coals preserve characteristic acoustic features of failure in self-sustained burning irrespective of the ignition cause. Phenomena which promote coal disintegration in heating are described. The failure mechanism of live coal in a seam is set, and appropriateness of the rating of the typical acoustic features revealed in coal burning on a lab scale is proved on this basis.

The article sets forth the studies on the longwall top coal caving technology with the powered roof support under development using the discrete element method in RockyDEM. The computer-assisted modeling with regard to geological and geotechnical conditions determines the LTCC technology parameters. They ensure the most efficient performance of the technology in terms of the integrated combination of caved coal mass, coal dilution, coal loss behind the support and frequency of poor roof caving events.

The problems connected with the adjustment of drill-and-blast patterns for the volume change in a charge cavity in case of deformation of borehole walls in case of drilling in open pit coal mining in the permafrost zone in Russia’s Far East are justified. The examples show that in drilling on benches 10 and 15 m high, 2-17% of boreholes require redrilling because of partial disintegration of rocks beyond the hole perimeter and due to caving of rocks inside the holes. In case of redrilling, the drill-and-blast patterns undergo decrease in the borehole spacing, which leads to the increase in the range of hazards in terms of the damage factors (flyrock and seismic impact). Borehole wall caving changes the charge cavity volume, which affects the quality of liquid emulsion explosive charges in mechanical pumping. A set of devices is proposed for the charge decoupling to ensure stability of the explosive charge cavity under conditions of large block blasting at mineral deposits situated in the zones of discontinuous permafrost.

The authors assess prospects for recycling of carbonate-fluorite ore processing waste in the Voznesensky ore district in the Primorski Krai. The main factors that can influence processing of slime are determined. The flotation-based recoverability of fluorite from low-grade (11.56-13.12% CaF₂) and fine-dispersion secondary material containing up to 88% of particles less than 10 µm is demonstrated. A rational process flow sheet to produce concentrates with CaF₂ content more than 93% mass at fluorite recovery to 52% is substantiated and proposed. Processibility of samples having different degrees of dispersion is compared. The use of electrochemically pretreated water in the process increases recovery of fluorite in concentrate by 3.6-4.7%. The variants of joint processing of charge material from different areas of the manmade deposit are discussed.

The article exhibits possibility of efficient treatment of coal siftings 0-13 mm in size as a case-study of the combined dry and wet separation of coking low-caking, low-metamorphozed coal. On the basis of estimation of processing behavior of the initial material, as well as the sieve, fraction and mineral analyses of different size grades of coal, several process flow sheets are developed. These process flow sheets include dry pneumatic separation of coal size grades of 1-13 mm, wet spiral separation of coal slime 0.2-3.0 mm in size, as well as flotation and oil agglomeration to separate coal and rock particles in fine coal slime. The proposed process flow sheets allow producing concentrates with the ash content from 15.3 to 9.9% at the mineral-free matter recovery to 90% and the calorific value over 7000 kcal/kg.

The articles describes the studies into the physical properties and composition of loparite ore processing waste from the dormant tailings ponds Karnasurt-1 and Umbozero in the Murmansk Region. The test samples were obtained by drilling to a depth to 4 m. The implemented studies included geological and geotechnical investigations, as well as the sieve, chemical, X-ray phase and radionuclide analyses. The properties and composition of the test tailings exhibited essential nonuniformity. The mineral composition is dominated by nepheline, and K- and Na-feldspar. The radioactivity of the waste is mostly due to radium and thorium. The obtained information of the peculiarities of change in the properties and composition of loparite ore mill tailings depending on their depth of burial are important for the development of the environmental measures and for the design of process flow sheets for manmade materials.

An engineering geological block model is conceptualized as a framework for the integrated digital model of a deposit. The scope of the article encompasses the methods of import and transformation of data from different sources, implementation of multi-level generalization, selection of scalable control systems for data bases and hybrid storage systems, as well as integration with MGIS, ERP and other information systems via standardized interfaces. It is shown that an engineering geological block model ensures highly accurate modeling, supports analytical and forecasting activities, becomes a single source of actual information on a deposit, and shapes a core of a digital twin of a mine. The engineering geological block model is the key element of digital information, which ensures data consistency, enhanced efficiency and risk reduction at all mining phases.