Home – Home – Jornals – Journal of Mining Sciences 2025 number 3

For metals, soil and rocks, a creep model non-associated with the Tresca and Mohr-Coulomb yield surfaces is discussed. The constitutive laws for creep in the model contain angles of internal friction and dilatancy. The authors propose a procedure for finding angles of internal friction and dilatancy using creep curves obtained from testing cylindrical samples. Determination of the time of failure at different irreversible strain rates and different initial stress levels uses the deformation-based and energy-based failure criteria applicable to both uniform and non-uniform stress states under long-term loading.

The analysis of dynamic events in the earth’s crust should take into account internal mechanical losses (energy dissipation) in rocks. Such dynamic events often have a frequency under 1 Hz. Internal mechanical losses are estimated in terms of the dissipation factor Q ^-1. Rayleigh damping represents the dissipation factor with respect to the direct and inverse dependence on frequency. The authors performed three-point bending tests of rock samples of different types and genesis. The dissipation factors are calculated for various frequencies of deformation. The empirical dependences of the dissipation factor on the frequency in a range of 0.003-0.100 Hz are approximated by Rayleigh damping. The coefficients of variation and determination are calculated to define conformity between the experiment and model data, the conclusion on the good agreement with the Rayleigh model is made, and the causes of differences between experimental and theoretical results are listed.

Thermal environment in vertical mine shafts has a significant influence on the shaft support and reinforcement, and on the safety of the while hoisting facility. Fluctuation of air flow temperature causes thermal deformation of structural elements in the shafts. Subzero temperature air enters mine shafts in the winter season because of deficient heating of air supply shafts and as a result of air flow reversal in ventilation shafts. As a consequence, tubing support in the shafts experiences cooling, the tubing joints open, and water inflow in the shaft goes over and above a guideline value, which can initiate an accident. The authors analyze the impact of subzero temperatures on the opening of tubing joints after change in the stress-strain behavior of the tubing ring-concrete lining-rock mass system. The developed and implemented numerical model of the mentioned geotechnical system determines patterns of temperatures and deformations in tubing rings in the periods of exposure to cold.

Mathematical modeling investigates the influence of an underpump tubing string on the longitudinal vibration intensity in the oilwell tubing and pumping unit assembly during operation of an electric submersible pump (ESP). The use of the underpump tubing strings with a length of ¼ wavelength with a dominant frequency of longitudinal vibrations of ESP reduces the vibration rate at this frequency by 2-3 times, and the diameter of the underpump tubing string is of no importance. Such underpump tubing strings in producing oil wells can help improve reliability and service life of ESP. When an underpump tubing string is set on the well bottom and pressed to the casing string along a spiral line, the longitudinal vibrations of the underpump tubing string transform into variable side stresses which influence the casing string and the reservoir rocks in the bottomhole formation zone, while no increase in the longitudinal vibration rate takes place in the pumping unit. The working ESP with the underpump tubing string rest on the well bottom conditions continuous vibration effects on a pay zone in the course of the well operation, which improves permeability of rocks in the bottomhole formation zone.

The seismic observations of dumps at the Mikhailovsky GOK open pit mine are carried out during mass blasting. The curves of the acceleration amplitude and velocity of vibrations in a blast-induced seismic wave and the reduced distance are plotted. The dynamic stability of the overburden dumps is estimated. It is shown that at certain reduced distances, multiple seismic effects of mass blasting can lead to the loss of the dynamic stability of the dumps. The results are applicable in mass blasting design and in location and parametrization of overburden dumps.

Support design in underground mining and tunneling excavations is dependent on the geological and geotechnical behavior of rock mass. The rock mass rating (RMR) and Q-System are the key parameters to design support system. The existing support system in tunneling projects along Himalayas were studied, and it was observed that the support was lighter in some cases and heavier in others. Based on the real time data obtained from active tunneling projects and geologic conditions along Himalayas, the modified support criteria (RMR₁₉) using back calculations and incorporating stress factor in RMR and Q have been applied in this study. The stress reduction factor of the Q-system was also studied. The existing and modified RMR and Q are statistically correlated with a significant R² value.

The article presents a theoretical substantiation of a dynamic adaptation process to adjust drilling and blasting patterns to structurally complex deposits and open pit mining using the integration of zoning theory and blast impulse theory. The key stages of approaches to drilling and blasting pattern designing are discussed. Emphasis is laid on the theory of rock fracture zoning with description of the zones of deformation, fracturing and seismic effect depending on the blast impulse. The calculation formulas are proposed to determine the blast impulse, radii of fracture zones and energy balance to ensure efficient rock fragmentation and minimization of adverse effects. It is critical to introduce artificial intelligence systems capable to analyze geological data in real time. The principles of creation of the intelligence control systems for drilling and blasting adaptable to varying geological conditions are developed. This can enhance safety and efficiency of drilling and blasting at mines operating at structurally complex deposits in Russia.

It is most effective to fracture very hard rocks by impact. On the other hand, application of the dynamic rock fracture method needs optimal parameters selected using modern techniques of estimation of rock fracture resistance dependent on the properties of rocks. The features of dynamic loading of an operating tool are discussed, and the classification of the dynamic rock testing methods is proposed. The rock crushability testing procedure is recommended. Resistance of rocks to fracture under dynamic loading is estimated, and the main estimation criterion is the volume yield of crushed material -7 mm in size. The strength characteristics of rocks from different testing methods were compared with the estimates of rock resistance to fracture by the selected criterion. The comparison shows a good agreement of the results, sufficient for engineering design.

The article discusses capacities and benefits of stripping with direct dumping within the mixed-type mining technologies for structurally complex deposits of solid minerals. The authors emphasize practicality of this technology in different geological and geotechnical conditions of mineral mining, and develop a procedure to determine a reasonable application range of the technology within the mixed-type mining systems. The resource-saving process flowsheets are proposed for dragline mining of centroclinal fold-type, water-encroached and steeply dipping bedded deposits. The most feasible ways of enhancing efficiency of overburden removal with direct dumping are discussed.

The mining drawing schedule is related to the safety, environment and ground pressure control of mine production, and is of great significance for controlling the economic indicators of mine operation in block cave mining. The mixed integer programming(MIP) method has been proved to be very effective in solving the medium- to long-term drawing sequence optimization problem in mines. The amount of ore, three kinds of the draw points priority order with diamond undercutting mode, and the logical relationship are considered as constraints based on the value model of ore-rock mixing. The maximizing net present value of the mining operation is used as objective function. Application and analysis of the model is solved using CPLEX, MATLAB, and YALMIP for a specific Chinese copper mine using 770 drawpoints over 7-year (28-quarter) periods.

The studies find out that permeability of loam is 51.6 times less than permeability of coal mass. Thus, this disperse sediment can be used to prevent spontaneous combustion of coal and carbonaceous rocks. The major insulating effect is provided by a loam layer with a thickness of 0.06-0.08 m, which reduces permeability of an insulated mass by 5 times. The increase in this loam layer thickness has a minor effect on the permeability. Water sprinkling yet more decreases the permeability of loam but drying-out initiates cracks in the insulating material and they give access for air to oxidizable coal. Recovery of the insulating effect after exposure to water requires ripping and compaction of loam.

The authors propose a model of activation of sphalerite flotation by lead ions using the mechanism of physisorption of a collecting agent. Flotation tests determined the recovery of zinc and the quality of the concentrate depending on the volume densities of lead and xanthate, the ratio of their mole concentrations and pH of the flotation system. The ratio of lead and xanthate mole concentrations of the increased sphalerite floatability, which is condition of casual activation of sphalerite, is found. The causes of suppression of sphalerite floatability at the increase in a certain concentration of the activating agent or xanthate are disclosed. On the basis of sphalerite floatability suppression, it is recommended how to enhance selectivity of separation of sulphides in the lead flotation circuit.

The review of literature and research findings exhibit current situation and the most challenging problems in theory of flocculation of mineral suspensions. With a view to enhancing efficiency of flocculants, it is advisable to have a science-based concept of selecting flocculants and their compositions, including functionally modified flocculants, with branched macro-molecules, with regard to laws of adsorption of flocculants at the surface of minerals. In the light of the revealed strength characteristics and laws of destruction of floccules, it is shown that for the further development of the theory, it is important to find interconnection of these parameters and fluid dynamics, and to study recombination of floccules. It is undoubtedly interesting to determine small concentrations of flocculants both for the analysis of formation of floccules and to disclose conditions of smart use of flocculants in the industry.

Because of the need to expand the range of promising Russian-manufacture reagents to replace import analogs, the authors study effect exerted by reagents from class of dithiocarbamates on the surface of sulfide minerals in composition of complex gold ore. New research methods are used to examine interaction of the test reagents with the gold-carrying minerals in flotation of complex ore. It is found that a new reagent of bis-piperazine dithiocarbamate is an efficient selective collector of mineral carriers of noble metals in flotation of complex gold ore. The test methods were UV spectroscopy, wetting angle measurement, scanning electron microscopy and laser scanning microscopy. Different adsorbed phases of the reagent on the polished section are determined and visualized. Selective attachment of the reagent at ore minerals can ensure their selective extraction in different concentrates in flotation of complex ore.

The article proposes technology of processing and modification of zeolite-bearing rocks from the Shivyrtui and Talan-Gozagor deposits with a view to producing high-quality adsorbents to recover rare alkali elements from hydromineral resources. The mineral composition of zeolite-bearing rocks is described, and their electromagnetic and electrostatic separation is reported. Using a model solution with cations of rare alkali elements, the sorption capacity of initial, concentrated and modified zeolite-bearing rocks from the Shivyrtui and Talan-Gozagor deposits is analyzed. Sorption of rare alkali elements is studied as function of a solution/sorbent ratio. The influence of cations in the model solution composition on the capacity of zeolite is examined. The water treatment tests show high results which ensure the required quality of effluents.

The article studies a new collector represented by a dithiazine-class complexing agent-1-carboxy-2-perhydro-(1,3,5-dithiazine)-5-il ethane (CPDE). The study of the physicochemical properties of the agent and its interaction with the mineral surfaces of galena and sphalerite used the methods of IR and UV spectroscopy, as well as measurements of wetting angle and free energy. It is found that the agent makes the surface of galena hydrophobic and the surface of sphalerite hydrophilic. The comparative flotation results indicate that the CPDE possesses higher selectivity as compared with the PBX agent and ensures selective separation of galena and sphalerite during flotation.

The Donbas region has accumulated hundreds of coal waste dumps, and not less than one third of them are self-heating. With a view to substantiating parameters of a system for temperature monitoring of self-heating coal waste dumps, the temperature field dynamics was analyzed using model fills. It is found that a fill of unoxidized waste rocks possesses more pronounced properties of a heat accumulator than a fill of oxidized waste rocks. The rate of average temperature variation and the temperature field nonuniformity of the model fills under influence of internal and/or external sources of heat emission are governed by both grain-size composition and thermal destruction of waste rocks. The features of temperature stratification of heated model fills are conditioned by their genetic structure and by spatial location of heat sources. The research findings are useful for determination of sampling times for heat meters, adjustment of their positions in subsurface zones of self-heating waste dumps, as well as for interpretation of temperature monitoring data of such man-made formations.

The deepest-level underground structures of various purpose are mines, tunnels, hydropower stations and underground research laboratories. The authors describe a possible classification of rockbursts by their initiation mechanism: ahead of a mined-out space, in a pillar, nearby a fault. The authors review the common applied systems of rockburst hazard prediction and select continuous measurement systems which produce data suitable for machine processing. The geodynamic situation prediction at a mineral deposit using artificial neural networks is described. The comparative test of machine learning methods for the analysis of geodynamic phenomena is carried out. The structure of artificial neural networks for the prediction of geodynamic phenomena and stability of underground openings is described. The seismic events in the Sheregesh Mine are selected for the analysis. It is found that different models accurately determine clusters of seismic events. k-means clustering produces the best results (97.92%).

The article presents an assessment algorithm for vegetation in areas of coal dust pollution. Two problems are solved: delineation of a dust pollution area by the Enhanced Coal Dust Index with data clustering; calculation of vegetation indexes in selected clusters for the vegetation analysis. Clustering used the Hill Climbing algorithm. The source data were Sentinel-2 imagery obtained during the spring and summer seasons. The algorithm was tested as a case-study of the mining area of the Urgal Coal Mine in the Khabarovsk Krai. The test data for a period one year long show the vegetation damage on drawing nearer the test mine area.