The program for the development of the national economy based on own mineral raw materials as adopted in the Socialist Republic of Vietnam requires an increase the volumes of minerals. This includes both liquid hydrocarbons, and non-traditional solid minerals. This paper examines the resource base of mineral deposits in the South China Sea. The objective was to determine and scientifically establish classification criteria for zoning (regionalization), as well as to identify prospective areas with deposits of ferromanganese formations and other solid minerals. An analysis was undertaken of placers on the shelf and deposits of ferromanganese formations in the deep areas of the Vietnam Sea. A multiparameter analysis of the hydrological, geophysical, engineering and geological, environmental conditions of the deposit positions was conducted. In addition, criteria for the prospects of the formation and development of deposits of ferromanganese formations were established. These criteria enabled areas with different prospectivity ratings to be identified. Within the South China Sea, zones (areas) with a high, medium, and low potential for the presence of nodules were identified. Similar zoning for the crusts was also identified. The areas of these zones were determined. The results of the research established that the total potential area of ferromanganese nodules is 91,480 km². The area with the potential of ferromanganese crusts is 2,421.6 km², while the area of coexistence of nodules and crusts is 18,777 km². Furthermore, priority regions for future exploration are those with high nodule potential covering an area of 18,110 km² and the regions of high crust potential with an area of 882.6 km². Based on the materials obtained, the bed of the Vietnamese Exclusive Zone of the South China Sea was zoned. Maps of the resource and predictive prospects of the seabed were drawn, and the prospecting and exploration operations can be established within this framework.

The goals of this study were to analyze the capabilities of DAS (distributed sensors) in resolving mining problems, compare them with existing seismoacoustic data collection systems, and prepare the basis for conducting seismoacoustic studies with recording by a fiber optic distributed system. This paper considers the capabilities of recording seismoacoustic responses using fiber optic distributed acoustic systems (DAS). Based on physical and geometrical analysis, the amplitude-frequency responses (characteristics) of recorded longitudinal waves for straight and helically-wound fibers were obtained. In the case of helically-wound fiber, the frequency response depends on several key factors: integrating the measured value along the fiber based on the measurement; the angle of incidence on the cable; and the winding angle of the fiber in the cable. An increase in the winding angle increases the uniformity of the amplitude-frequency characteristics of longitudinal waves both in terms of frequencies and angles of incidence. At the same time, helical winding changes the effective response spacing (gauge length). This makes it possible, by summing the responses of the straight and helically-wound fibers due to the overlap of the spectra, to record frequencies that are suppressed in case of separate recording. Based on the study results, a cable design was proposed to record broadband seismoacoustic responses enabling a wide range of mining and engineering problems to be resolved, and for seismic surveys both in wells and on the surface to be carried out.

In rock physics, much attention has been paid to the study of the processes of strain of natural materials    at small strains. Experiments using high-precision measurements have allowed new knowledge at micro/nano level to be acquired. The microplasticity of solids is studied in materials science, but there is also data regarding some rocks. The property of microplasticity of natural materials is still little studied.  The study was carried out on rock samples. The effect of strain amplitude and confining pressure on the velocity and attenuation of P and S waves in dry and water-saturated sandstone has been studied. The method of reflected waves was used in the frequency range of 0.5–1.4 MHz at four strain amplitudes (0.5–1.67)·10⁻⁶ Amplitude cycling causes an open and closed hysteresis effect for wave velocity and attenuation. This has been observed for both dry and water-saturated sandstone. The hysteresis loop overlaps in both states. The amplitude changes in the velocity of P-wave in dry sandstone is 1.12 %, and the attenuation of P-wave in dry sandstone is 5.43 %. As for S-wave, its maximum attenuation in dry sandstone reaches 8.81 %. The behavior of a wave velocity and attenuation can be explained by the combined effect   of viscoelasticity and microplasticity. Elastoplastic transition strongly depends on the details of the microstructure, its defectiveness, and other parameters. The characteristics of the complications of wave parameters can be the signs of the internal structure of the subject.

Rock joint hollowness coefficient is an important parameter when resolving practical mining problems. Geophysical methods used to resolve this problem are indirect. Thus the interpretation of their results may cause certain difficulties as a result of the uncertainty of the physical relationships between the parameters of joints and the measurement results. One of the ways to resolve this problem is to combine experimental research methods with analytical and numerical simulation. The studies were aimed at investigating the electrical conductivity of a two-dimensional medium in the presence of thin insulating (non-conducting) joints. This paper proposes an analytical method for assessing the dependence of the specific conductivity of a medium with inclusions in the form of elliptical joints on their half-length. This dependence is show to have the form of an exponent depending on the square of the length of the maximum semi-axis as an argument. The simulation method is based on the assumption of the elliptical shape of a joint when the length of the minor semi-axis of the ellipses tends to zero. A review of publications and their results presented in this paper showed that this method for determining the specific conductivity of the medium with thin joints is one of the best in terms of compliance with experimental data. Its predictions are close to those of the Effective Media Approximation (EMA). However, the proposed method is distinguished by the simplicity of the formulas and their physical visibility essential for the use in interpreting the data of a physical experiment. In two-dimensional formulation, numerical simulation of the specific electrical conductivity of a sample of a medium measuring 1×1 m with elliptical joints of conductivity less than that of the matrix was carried out in the COMSOL Multiphysics environment. A square sample of unit sizes with unit conductivity was considered in which 25 joints with uniform distribution along the length occurred. 40 models were built wherein the maximum length of the joints varied from 0.01 to 0.4 sample size in increments of 0.01 m. The satisfactory concordance of the results of numerical and analytical models, both visual and confirmed by statistical estimates, has been shown. It was noted that when the size of the joints changes to achieve the value of the maximum semi-axis α = 0.15 m, the influence of single joints that do not extend beyond the boundaries of the sample prevails. Above this value, at α > of 0.15 m, the influence of joint coalescence, as well as their extension to and beyond the sample boundaries begins to affect. Comparison   of the proposed theoretical model of electrical conductivity, depending on the square of the length of the maximum semi-axis of a joint, with a similar model in the form of an exponent with a linear dependence showed a better concordance of the proposed model with observations at the stage of the lack of joint coalescence and their extension to the sample boundaries at α < 0.15 m. At α > 0.15 m. The proposed model has a lower coefficient of determination compared to the full range including both intervals, but higher than that of the model with a linear dependence in the exponent argument. This indicates the universal nature of the proposed model.

In recent years, with the development of techniques and methods for in-situ leaching (ISL), additional uranium extraction from previously worked-out blocks is becoming not only relevant, but also quite achievable. In this case, the extraction of residual uranium reserves from previously worked-out blocks does not require additional costs for the necessary infrastructure. One of the most important factors in the formation of residual uranium reserves in worked-out blocks is the presence of clay minerals in the ore horizon. In this regard, we conducted a number of studies on the adverse and positive effects of clay minerals on ISL process. Water permeability and relatively good filtration (not less than 0.5–1 m/day) of ores and rocks of a productive horizon (aquifer) is the most important hydrogeological factors affecting the performance of uranium ISL. The second most important hydrogeological factor is the lack of fluid communication between the productive aquifer and nonproductive aquifers, i.e., the obligatory presence of aquicludes. The role of clays in these hydrogeological factors is twofold. On the one hand, the presence of clays negatively affects both the solutions filtration rate and uranium extraction. On the other hand, the presence of clay minerals (forming an aquiclude) enhances the effect of ISL. The study findings allowed the role of clay minerals in uranium ISL to be assessed. The diffusion coefficients of nitrate ions in the clays were determined, and the protective effect of aquicludes was calculated. The effect of the clay content in the ore sand horizon on the solutions filtration coefficients was also established. The static uranium exchange capacity of clays was determined by studying the process of uranium sorption by clay samples from sulfate and bicarbonate solutions. The studies established the diffusion coefficients of nitrate ions in montmorillonite and kaolinite clays, which amounted to 3.34 10⁻⁶ and 2.14 · 10⁻⁶ cm²/s. Taking into account the calculated values of diffusion coefficients, the protective time of the clayey aquiclude for nitrate ions was 43 years. At 20 % clay minerals content, the solution filtration coefficient decreases to values where ISL conditions become unfavorable. It was found experimentally that the sorption of uranium by clay minerals depends on both the nature of the clays and the composition of the solution. Uranium sorption from sulfate solutions proceeds noticeably better than that from bicarbonate solutions. The highest values of the static uranium exchange capacity were obtained for bentonite (104 mg/g).

Determining the sources of hazardous and toxic substances released into mine air, their gas composition, as well as providing each such source of pollution with the required amount of fresh air are important issues in terms of ensuring normal healthy and safe working conditions for miners. This paper studies blasting as one of the most dangerous sources of mine air pollution. The study was carried out for a long dead-end exploration working, and a development (preparatory) working of a copper-nickel mine. In accordance with the federal rules and regulations (FNiP), a number of requirements, including monitoring of gas hazard at a face, is applied to blasting operations.

The study examined the behavior of gas-air mixture in dead-end mine workings after blasting. The findings are based on the experimental data obtained in the conditions of two dead-end workings at an operating coppernickel mine. A technique for the experimental studies of gas release after blasting in a dead-end working was developed. The main technical characteristics of the instruments involved in the in-situ measurements are given. Time dependences of the concentrations of toxic gases after blasting at the blasted working mouth,   at the return ventilation current, and near a booster were established. In order to assess the reliability of the data obtained, the volume of released carbon oxides was calculated based on the data of gas analyzers and chemical reactions of explosives decomposition during detonation, depending on the types and weights of the explosives. A model of gas-air mixture transfer was described, constructed, and calibrated allowing for longitudinal dispersion. The Voronin model was used to simulate the gradual removal of toxic gases from the working face and solving the problem of boundary conditions. Based on experimental data, the coefficients of longitudinal dispersion, ventilation efficiency, and volume concentration of the considered gas admixture in the mixing zone at initial time were determined for a long dead-end mine working.

The constructed gas-dynamic model and longitudinal dispersion coefficients obtained as a result of the analysis enabled the time required for long dead-end mine workings ventilation to be analysed and estimated. Based on the model, the algorithm for calculating the velocity of spreading the combustion products in a mine ventilation network in emergency situations is being improved. The value of longitudinal dispersion coefficient for different operating conditions is also being refined.

Based on the gas distribution simulation within the interval of 1,500 m from a working face, the time required for the ventilation of a dead-end mine working was determined.

An increase in the rate of coal mining and a reduction of its prime cost can be ensured by comprehensive mechanization and automation of the system of mine auxiliary transport through the widespread introduction of overhead monorail tracks. The potential use of mine monorail tracks are conditioned by the following factors: low payload ratio of the train; reduction of the mine workings cross-section area due to transfer of auxiliary transport to the upper part of the workings; high operational safety; as well as the possibility of dismantling the track in the unused sections and subsequently installing it in new mine workings. The use  of rubberized rollers in the drives of mine monorail locomotives enables the coefficient of adhesion of the wheel with the monorail to be increased. It also reduces dynamic loads and the noise level during operation. The purpose of this research is to assess the durability of polymeric rims of drive wheels for mine monorail locomotives, taking into account their operating conditions. Stress distribution over the contact area of the wheel rim with the monorail was determined, enabling the development of measures to increase the service life of drive wheels of mine monorail locomotives to be developed. It was established that the effect of the monorail track deformation has no significant impact on the durability of drive wheel rims of mine monorail locomotives. A mathematical model was obtained to determine the durability of drive wheel polymeric rims, taking into account the maximum dynamic forces arising during the contact of drive wheels with the monorail. The durability of wheel polymeric rims of mine monorail locomotives was assessed in accordance with the Bailey criterion with regard to the maximum values of dynamic contact loads arising during the monorail train movement. It was also established that an increase in the carriage mass from 20 to 47 kN leads to 32 % less durability of a monorail locomotive drive wheel rim (from 8700 to 5900 hours).

A significant portion of mineral deposits developed by open-pit mining is opened to the full depth by road transport ramps without the use of combined transport. In most cases, this is dictated by the high rate of a pit deepening and multi-stage development. In this study, the energy intensity of rock mass (RoM) haulage from the working zone of a pit to the surface is considered at several hierarchical levels. Mineframe software was used to study 3D-models of open pits with different slope angles in order to test the method of analytical calculation of a pit volume that allowed ensuring accuracy under a wide range of mining conditions. The findings of the research are as follows: with an increase in the pit bottom diameter, the zone of stabilization of rock mass lifting (haulage) height shifts to greater target depths. An increase in the pit slope angles entails shifting the weighted average height to deeper elevations. By increasing the pit target depth, combined modes of transport become more economical in comparison with dump trucks due to an increase in the total volume of rock mass. Depending on the comparison purpose, it was proposed    to use different types of energy intensity. For a broad estimation of the rationality of the pair “scheme of opening – mode of transport” for open pits, the ratio of potential energy intensities of rock mass haulage   of a considered option of a pit opening and its basic option without transport berms was used. The ratio of potential energy intensities as a function of a pit depth was determined. The values of total energy intensity of rock mass haulage from a pit to the surface were also established.

Successful mining businesses rely heavily on the safety and reliability of their mine power distribution systems. Mine power distribution systems are designed to withstand an aggressive environment with a range of hazards. The harsh operating conditions require improvement to personnel protection systems through the study and simulation of the electric network’s normal and emergency operations. The purpose of this study is to assess insulation leakage current using an equivalent circuit of a mine power distribution system. The simulation identified the key properties of the equivalent circuit which can model potential hazardous situations. We also selected the quantitative metrics and the equivalent circuit property ranges. In order to simulate the transients, we recommended using the time constants for the oscillation damping in circuits, the insulation phase resistance properties, and the absorption currents. This paper presents the equations to estimate these values. As an example, we considered the equivalent circuit of a mine power distribution system with an R-L filter in the residual current device line. The equivalent circuit helps analyze the current leakage when a person touches a live phase conductor accounting for low-frequency polarization in the phase insulation. The proposed approach to the simulation and analysis of the insulation current makes it possible to generate an equivalent circuit of the mine power distribution system to analyze phase voltage asymmetry, trip currents of residual current devices, low-frequency polarization of the insulation, and the leakage current effects on the human body.

Digitalization and digital transformation of companies have turned from global trends to an urgent need. Thanks to digitalization and digital transformation, organizations can overcome the times of crisis, the times of lockdowns with less losses and respond more effectively to any adverse changes in the external environment. The assessment of the level of digitalization and digital transformation allows to determine how fast the processes of introducing digital technologies and optimizing processes with digital solutions proceed, both in companies and across the industry as a whole. The article provides an analysis with the systematization of foreign and domestic methods, methodological approaches, methods for assessing the digitalization level and digital transformation, as well as reveals their positive and negative aspects. Based on a comparative analysis, an improved author-developed methodological toolkit is proposed for assessing the level of digitalization and digital transformation, alleviating the disadvantages of the existing methodological experience. The approbation of the author-developed methodological toolkit was performed using the oil and gas industry as an example; the following companies, being the industry leaders, were analysed: PJSC “Lukoil”, PJSC “NK “Rosneft”, PJSC “Gazprom”, and PJSC “Tatneft”. According to the results, the digitalization and digital transformation processes of the domestic oil and gas industry are insufficiently dynamic. It was found that in the period from 2016 to 2020, the Russian Federation industry leaders were in the following order from the most advanced to the least advanced in terms of the digitalization level and digital transformation: PJSC “Gazprom” topped the list; PJSC “NK “Rosneft” was second; PJSC “Lukoil” was the third largest company, and PJSC “Tatneft” held the fourth position.