The relevance of the subject is determined by the need to solve the problem of ensuring the safety and prevent failure of facilities containing an interface between rock and concrete. These include mine shafts, hydroelectric dams in mountainous areas, reinforced concrete tunnel supports and others that are subjected to both static loads from overlying rocks and soils and dynamic loads from explosions and earthquakes. We perfomed laboratory tests according to the International Society for Rock Mechanics (ISRM) methodology on specimens with interfaces between gypsum stone and sand-cement mortar. The fracture toughness coefficient K_IC of the interfaces in the specimens was investigated. The cylindrical specimens were 40 mm in diameter and 150 mm long with a V-shaped notch in the middle part. The specimens bending strain measured using a three-point pattern allowed the K_IC to be determined based on the maximum force at 5–6 cycles. The average K_IC value for interface between rock and concrete proved much lower than that for rock and even for specimens made entirely of concrete. For the specimens without concrete, the average value was 1.327 MPa×√m, and for fully concrete specimens, 0.858 MPa×√m. The average value K_IC for the specimens with concrete was 0.323 MPa×√m, which was 4 times lower than that for the specimens without concrete and 2.5 times lower than that for the concrete specimens. The formation of a calibrated fracture during testing results in a relative increase in the internal mechanical loss factor Q⁻¹, determined by the resonance method, by up to 30%. This allows estimating K_IC fracture toughness coefficients of rock-concrete interfaces using Q⁻¹. The obtained results can be used in actual practice in the design, operation, and organization of nondestructive testing and monitoring of industrial mining facilities that include these interfaces.

In a number of cases during construction and operation of engineering facilities, development of mineral deposits it is necessary to improve the properties of sandy soils by strengthening them with polymer compounds. Analysis of current research shows that the effect of flow rate and method of treatment with polyurethanes on the acquired properties of loose rocks is poorly understood. The paper presents the results of laboratory research of chemical strengthening of sandy soil with polyurethane compounds. Geomaterials typically produced by strengthening loose rock with highly elastic polymers have low strength properties and are stable under only minor loads. To improve the strength, a two-binder sandy soil treatment process is proposed, which includes sequential mixing of the soil with a two-component highly elastic slow-reacting compound and a small volume of a fast-curing one-component resin. The aim of the work is to experimentally investigate the dependence of strain and strength properties of sandy soil on the method of mixing with polyurethane compounds and the polymer volume flow rate. A standard one-component method of mixing samples with highly elastic resin at the resin-to-sand volume ratio from 0.05 to 0.4 and a two-component method including additional treatment with fast-curing one-component resin in the volume of 5 % of the strengthened soil were experimentally tested. The effect of polyurethane resins on rock properties was evaluated by triaxial compression strength tests. Electron scanning microscopy was used to determine the content and distribution of cured polymers in the loose rock structure. It was found that the addition of a fast-curing polyurethane compound in the two-component mixing method leads to the formation of aggregates of cured polymer, binding mineral grains without continuous filling of intergranular voids. The presence of such aggregates improves the strength characteristics of sand up to 5 times that is 1.3–3 times more than at the standard one-component mixing with highly elastic resin at a resin-to-rock to be strengthened volume ratio up to 0.3. It was found that under triaxial compression conditions, the geomaterial obtained by the two-component mixing method withstands higher axial stresses. In case the volume ratio of resin to rock is more than 0.3, the strength of the produced geomaterial does not depend on the addition of the fast-curing compound. The study findings practical significance consists in increasing the strength of a sandy soil due to its low-volume strengthening with highly elastic polyurethanes.

The results of gas-air surveys conducted at the mines of the Verkhnekamsk potassium-magnesium salt deposit indicate that the volume of gaseous impurities recorded in the main ventilation drifts is often significantly lower than in the working areas of dead-end workings. Many studies attribute the reduction of gas impurities along the ventilation airflow path in potash mines not only to the dilution of harmful impurities due to fresh air leakage from intake drifts but also to the neutralization of gases through chemical reactions with the potash rock mass. Previous laboratory studies have shown that sylvinite (NaCl + KCl) is capable of absorbing impurities of toxic and combustible gases. Based on these laboratory findings, the present study was conducted under real mining conditions, taking into account the dynamics of gas impurities in the underground atmosphere and the dilution effect caused by air leakage. As part of this study, measurements of combustible and toxic gas concentrations were conducted in productive seams of varying mineral composition at one of the mines of the Verkhnekamsk potassium-magnesium salt deposit to assess the influence of potash salt properties on the gas balance in long dead-end workings. An analysis was conducted to assess the extent to which the properties of the potash rock mass influence changes in the concentration of combustible and toxic gases in the workings along the ventilation airflow path. The collected air samples were analyzed under laboratory conditions. The concentration of combustible gases, carbon monoxide, and carbon dioxide in the collected air samples was determined using gas chromatography with the CHROMOS GX-1000 instrument. The contribution of gas neutralization and dilution due to leakage from the ventilation ducting to the reduction of combustible and toxic gases in the outgoing airflow from the working area was evaluated. The results of the conducted tests established that in long dead-end chambers of seam AB (100 m or more), the volume of gaseous impurities decreases along the length of the working from the dead end to the entry. The study accounted for factors that could influence the reduction of gas concentration in the working area.

The expansion of mining in potash mines has faced the problem of fresh air shortage, which cannot be solved within the current paradigm of self-contained ventilation. Prospects are related to sequential and recirculation ventilation, as well as the concept of "ventilation on demand", requiring a detailed description of the processes of "self-cleaning" of a mine air from dust. Crushing a rock mass results in the formation of many aerosol hygroscopic salt particles, which in humid air conditions aggregate and settle on a drift floor. Accurate mathematical models are necessary for predicting the dispersion of these particles and associated gases. The paper considers the regularities and mechanisms of the effect of relative air humidity on the size of salt dust particles, aerosol hygroscopic salt particles of halite (NaCl) and sylvin (KCl). The interactions at the contact "salt surface – humid air" are described and the current understanding of the hysteresis processes and the stages of deliquescence and efflorescence (recrystallization) of hygroscopic aerosol particles are considered. Due to the fundamental difficulties of using modern experimental electronic equipment in the conditions of underground mines, data on oceanic aerosols of the same chemical composition were involved in the analysis. A number of models of hygroscopic growth of oceanic aerosol particles were reviewed and then adapted to the conditions of a potash mine atmosphere that made it possible to obtain average values of the factor of a salt aerosol particle hygroscopic growth. The good convergence of the known scientific data on the changes of the hygroscopic growth factor depending on relative air humidity for both oceanic aerosol and salt dust aerosol characteristic of a mine air was shown. The obtained theoretical-empirical data characterizing the changes in the size of salt particles depending on relative humidity were tested in model studies with salt aerosol. Young's model was proposed to interpret and predict the changes in the size distribution of salt aerosol particles. The heuristic value of the proposed approach was confirmed by the example of the Young's model record in log-log coordinates. The results of the study can be applied to calculate the processes of dust conditions formation in rock-salt and potash mines.

Mining and metallurgical operations are inextricably connected with the consumption of large volumes of water and, consequently, the generation of liquid waste. The priority is to solve the problems of treatment and rational reclaiming of process waters with high content of valuable components. This will make it possible to obtain a significant environmental and economic effect, i.e. to bring profit directly to enterprises, save material resources and reduce the environmental impact in mining regions. Processing of copper-zinc ores is accompanied by the formation of metal-bearing wastewater with a wide range of associated metals and nonmetals with low concentrations of each individual component and pH fluctuations within wide ranges. These factors make it difficult to select a rational treatment technology, so enterprises have to pay for excessive metal-bearing discharges into the environment. Heavy metals are toxic, do not undergo decomposition, can be accumulated by aquatic plants and reach a human body through the food chain. Centralized accumulation of accidental discharges, surface and drainage water with subsequent treatment for use in recycled water supply can solve a number of environmental problems in the field of water resources protection. Adsorption of heavy metals by zeolites produced from inexpensive clay minerals due to the simplicity of the process, possibility of zeolite regeneration, high efficiency in Cu²⁺, Zn²⁺ and Fe²⁺ ion exchange with release of non-toxic  Na⁺ cations into the environment is a good alternative to chemical precipitation. The purpose of this study is to optimize the conditions for producing zeolites from kaolin and bentonite with the assessment of the possibility of their use for the treatment of wastewater generated during mining and processing of ores from sulfide copper-polymetallic deposits. The technology of alkaline fusion of bentonite or kaolin with sodium hydroxide was used as a basis for zeolite synthesis from crude mining products. The novelty of the technological approach in obtaining zeolites from natural aluminosilicates in comparison with the published data is that the adjustment of the chemical composition of alkaline alloy for the synthesis of zeolites with a certain crystal structure was carried out using Al₂O₃–NaAlО₂ waste suspension. The alkaline alloy was dissolved in water, filtered, and subjected to hydrothermal crystallization. The phase composition of the zeolite adsorbents was studied. Through studying the recovery of heavy metals from model solutions, the mass composition and conditions of alkaline fusion processes as well as the hydrothermal crystallization mode were optimized. The achieved metal recovery of 95% from the model solutions with initial concentration (mg/L): 150 Cu²⁺, 180 Zn²⁺ and 125 Fe²⁺ allowed to draw the conclusion that zeolites based on bentonite and kaolin can be used in the treatment of metal-bearing wastewater.

Finely ground tailings from flotation processing of waste copper reverberatory smelting slags of the Sredneuralsky Copper Smelter ("SUMZ technical sands") was accumulated in significant amounts and may pose a threat to the environment as a potential source of heavy metals. At the same time, the waste can be considered as a promising source of useful components due to relatively high contents of zinc (3.3–3.9%) and copper (0.4–0.5%). Development of technologies for recycling the "technical sands" is a promising task of nonferrous metallurgy and requires their comprehensive study. The purpose of this research was to study the material composition of magnetic fractions of the "SUMZ technical sands" and assess the prospects of extraction of useful components (zinc and copper) from their flotation tailings using wet magnetic separation. Chemical analyses of the obtained fractions were carried out at the Center for Collective Use "Geoanalitik" of the Institute of Geology and Geochemistry, UB RAS by inductively coupled plasma mass spectrometry method using an Elan-9000 quadrupole mass spectrometer. Phase analyses were carried out at the Ural-M Collective Use Center of the Institute of Metallurgy, UB RAS by X-ray phase analysis using a Bruker D8 Advance diffractometer. The magnetic properties of the magnetic separation fractions were studied by thermomagnetic analysis. After treating the tailings by wet magnetic separation, the yield of the magnetic fraction (48 kA/m) was approximately 83%, that of the weakly magnetic fraction (200 kA/m) was 11%, and that of the non-magnetic fraction, 6%. The data on the phase and chemical composition of the tailings magnetic separation fractions were obtained. It was found that zinc and copper were distributed relatively uniformly among the fractions with a slightly higher content of copper in the non-magnetic fraction and that of zinc in the weakly magnetic fraction. The dependence of magnetic susceptibility of the "technical sands" minerals on the presence of isomorphic impurities in them was confirmed. The joint evaluation of the data of X-ray phase and thermomagnetic analyses showed that at practically identical X-ray diffraction patterns the thermomagnetic curves in the range of 20–700°C demonstrate significant differences between the magnetic separation fractions. All the obtained thermomagnetic curves are irreversible. At the used parameters of wet magnetic separation, this method proved inefficient for the "technical sands" separation, and additional research is required to find optimal methods of the tailings pretreatment and magnetic intensity modes. The research findings contribute to the study of magnetic properties of copper-smelting slag processing tailings and are of interest for the development of new flow schemes for their utilization and recycling.

During the operation of hydraulic excavators, the technical condition of pumps deteriorates due to wear, leading to increased internal clearances, fluid leakage, a reduction in volumetric efficiency, and higher energy losses, ultimately resulting in excessive fuel consumption. The objective of this study was to determine the optimal service life of pumps, taking into account the growing fuel overconsumption during operation. The following tasks were addressed: developing a mathematical model for pump ownership costs, incorporating progressive fuel overconsumption; designing an algorithm and conducting computer simulations using Simulink-Matlab; and assessing the increase in fuel consumption. The study examines the impact of the technical condition of the main hydraulic pumps on fuel overconsumption using the Komatsu PC2000-8 hydraulic excavator as a case study. Based on the proposed pump operation cost model, which accounts for the increase in fuel consumption over time, dependencies between fuel overconsumption and pump wear were established. Computer modeling was performed in Simulink-Matlab and Excel based on the developed calculation methodology and software algorithm. Relationships between the excavator's fuel overconsumption and the technical condition of the pumps were identified. A mathematical model for pump ownership costs is presented, taking into account the progressive fuel overconsumption during operation, along with the resulting equation for determining the optimal service life of pumps to minimize total costs, including pump acquisition and fuel expenses. This expression considers the technical condition of the main pumps, their rate of deterioration, fuel costs, and pump replacement costs. A fuel overconsumption indicator was introduced, defined as the ratio of the difference between actual fuel consumption per 1 m³ of excavated material and fuel consumption at nominal efficiency of the main pumps (nominal fuel consumption) to the nominal fuel consumption. The application of this criterion, in conjunction with the proposed equation for determining the optimal pump service life, allows for a data-driven selection of the critical wear threshold for the main pumps, reducing total ownership and fuel costs by up to 17%, depending on economic and mining-engineering conditions.

The mechanical transmissions of the hoist and drag winches, as well as the crowd mechanisms of mining shovels, operate under highly variable and shock cyclic loads. These severe operating conditions impose stringent quality requirements on both the manufacturing and assembly of such transmissions. The lifecycle management process for these gearboxes includes running-in and acceptance testing at the manufacturing plant, followed by diagnostics and condition monitoring during field operation. Test benches designed for these purposes must closely replicate the operating conditions experienced by the transmission in actual service. The developed test bench is designed to perform running-in (initial wear-in of mating surfaces) and quality control testing of hoist and crowd winch gearboxes installed in electric mining shovels of the following models: EKG-8US, EKG-10, EKG-12K, EKG-15M, EKG-18, EKG-20KM, and EKG-32R. These operations are carried out as part of the standard acceptance testing procedure. The test bench is equipped with DC excavator motors rated at 350 kW (drive motors) and 560 kW (loading motor). The hoist winch gearbox from the EKG-15M shovel serves as the torque multiplier. Two intermediate shafts are connected via an intermediate coupling, with the loading motor driving one of these shafts. Motor control is implemented using standard DC transistor converters with PWM control, identical to those used in mining shovels equipped with DC main drives. The running-in and testing processes are carried out using the mutual loading method, which enhances energy efficiency by allowing regenerative energy to be reused within the system. The test bench software is based on the Pulsar-7 information and diagnostics system, which supports the following operational modes: 1. Interactive manual control, enabling the operator to verify the functionality and calibration of test bench components. 2. Automatic control of the running-in and testing processes, where pre-programmed sequences from a built-in library generate the required control commands for each specific test type. Available test modes include: unloaded running-in, running-in under constant load, running-in under variable load and rotational speed, excavation cycle simulation. 3. Automated test report generation, including the ability to view and print previously generated reports. 4. Software configuration and auxiliary functions, including an embedded help system. A mathematical model of the mechatronic system was developed and used to simulate the running-in process of the EKG-15M crowd gearbox in Simulink. The developed test bench system has been successfully implemented at Joint Power Co., Ltd. (Moscow) and IZ-KARTEX named after P.G. Korobkov.

The economic efficiency of high-performance mining enterprises largely depends on the parameters and operating modes of energy-intensive equipment. Ventilation fans and hoisting machines are traditionally considered among the most energy-intensive equipment. This study focuses on analyzing the operation of the main ventilation fans and hoisting equipment at the Molibden mine and on developing measures to ensure optimal operating conditions aimed at improving energy efficiency and reducing operating costs. The paper presents methods for evaluating the efficiency of mine ventilation systems, including analytical approaches applied in system design and performance assessment. The study draws on operational data from the Molibden mine. The analysis revealed that the ventilation fans were operating inefficiently, with excessive specific energy consumption. Consequently, the replacement of electric motors is proposed to reduce energy use and operational expenditures. Calculations indicate that the expected economic benefit from replacing the ventilation fan motors at the Molibden mine amounts to 4.9 million rubles per year. Based on an analysis of the hoisting equipment characteristics, a required motor power assessment was performed. The study demonstrates that the use of modern multi-rope hoisting systems with balanced designs is essential for improving operational efficiency. Measures to optimize equipment utilization are proposed, which would reduce the specific energy consumption associated with ore extraction. An analysis of eight years of data revealed an inverse correlation between ore output and specific energy use: a 10–15% increase in productivity results in a 2–5% reduction in specific energy consumption. Avoiding periods of low equipment utilization and implementing automated control systems can significantly enhance overall system efficiency. The findings of this study may be applicable to other mining enterprises operating under similar conditions, particularly those engaged in deep-level mining.