The article is devoted to the study of dynamic interaction of rail track and freight wagons under increased axial load. In conditions of increasing the freight traffic volumes and axial loads, the importance of accurate understanding of the mechanisms affecting the wear of rail track elements becomes especially important. In this paper the authors have carried out experimental research and comparative analysis of freight wagon trolleys of different models. As a result of dynamic tests of the freight wagon trolleys, the necessary parameters of dynamic qualities of different models of wagons and their optimal values of axial loads of freight wagons are obtained. The necessity of improving the current design of wagon trolleys and reinforcing the design of railway track with the use of R65 type rails and reinforced concrete sleepers is substantiated. According to the data of trolley design comparison of different models, the bending moment and maximum load indices are established. © 2025 UNIVERSITY OF ZILINA. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC BY 4.0), which permits use, distribution, and reproduction in any medium, provided the original publication is properly cited. No use, distribution or reproduction is permitted which does not comply with these terms.

The research purpose is to study the forms of gold occurrence in the Takyr graben alluvial-proluvial deposits in order to develop a low-waste resource-saving processing technology. Methods. At the first stage, in the course of field studies, the geological structure of the site is specified, samples are taken for mineralogical-technological analysis, which includes the following procedures: studying granulometric and mineral composition of detrital material; fractional gravitational beneficiation of the source material; fractional beneficiation of material pre-processed in the autogenous mill (AG mill); studying free (native) and bound gold in beneficiation products, their quantitative assessment. The samples are processed under the three-stage scheme using an autogenous mill for sample preparation. Findings. For the first time, the geological structure of the site has been specified with the identification of the deposits in the Turangi and Tuzkabak suites within its boundaries, as well as granulometric and petrographic composition of gold-bearing deposits, and the specifics of gold bearing. The detrital material, represented by quartz with a sharply subordinate amount of quartzite, quartz diorites and jasperoids, is practically identical in all fractions. Originality. For the first time, various types of gold mineralization have been identified in placer sands: clastogenic, newly-formed hypergene, newly-formed hydrothermal and residual. Fractional beneficiation makes it possible to estimate the gold con-tent in each fraction and gravitational beneficiation products, as well as the ratio of free and bound native gold in different frac-tions. The largest amount of free native gold has been revealed in fractions of-0.25 + 0.1 mm (60%) and-0.074 + 0.044 mm (~40%). Gold is high-grade (96.5%) with an admixture of silver and iron. Together with gold, ilmenite, zircon, scheelite, native bismuth, as well as barite, galena, sphalerite, and dolomite have been identified. Practical implications. The research results make it possible to reassess the prospects of similar objects, to adjust the scheme and methodology for processing stream-sediment samples, to solve the issues of productive sand processing technolo-gy, as well as to improve the efficiency of geological exploration and eliminate the “underestimation” of gold deposits. The results obtained can be recommended for implementation by both domestic and foreign organizations specializing in the exploration and mining of gold deposits

The aim of the study is to create a unified diagnostic criterion suitable for the effective assessment of the current condition of pumping equipment and for predicting the development of degradation processes. The article addresses issues related to vibration diagnostics and the evaluation of the technical condition of pump units. As part of the research, a sample of diagnostic data based on the vibration parameters of centrifugal pump units was used. The methodology for conducting vibration diagnostics on operating equipment using a vibration analyzer is described. To process the vibration signals, methods of direct spectrum analysis (autospectrum) and envelope spectrum analysis were applied, allowing for the determination of the signal's frequency components. The results of spectral analysis of the vibration signals from the bearing assemblies of the centrifugal pump unit are presented. The scientific novelty of the research lies in the development of a digital monitoring system for the operation of pump units, which represents an important step towards increasing the efficiency and reliability of pumping equipment. As a result of the study, fundamental diagnostic features for assessing the technical condition based on vibration parameters were developed, making it possible to create a unified diagnostic criterion for the assessment and prediction of the condition of centrifugal pump units.

The study addresses the development of an envi ronmentally sustainable and economically efficient technol ogy for processing low-grade molybdenum ore. Methodol ogy: Particular attention was given to the effect of roasting temperature on the phase composition of intermediate prod ucts and the subsequent recovery of molybdenum. Experi ments were carried out in 2023 using ore from a Kazakh stan molybdenum deposit. Results: The results showed that roasting at 550 °C provided the most favorable conditions, yielding up to 88.28% molybdenum trioxide (MoO3) and ensuring a high extraction rate of molybdenum into solution (97.79%). From the purified solution, calcium molybdate (CaMoO4) was obtained that complied with MDK-2 grade requirements, with molybdenum content of 47.6%, phospho rus 0.0317%, and sulfur 0.253%. These findings demonstrate that even low-quality ores can be efficiently processed to produce a commercially valuable product, while minimizing both material losses and environmental impact.

In connection with recent economic events in the world, the problems of providing countries with energy resources have become particularly relevant. A special role in solving these problems belongs to the mining enterprises of Uzbekistan, which today are characterized by the further development of the openpit mining method, one of which is the Angren coal mine. The main task, its relevance, is to present one of the ways to model the optimal options for the operation of cyclic flow t echnology i n d ifficult con ditions of stripping operations. The methods used. In this work, finite e lement m ethods a nd mathematical modeling based on the computer program “Ansys” were used to model the structures of the Central Processing Plant in order to determine the optimal parameters of the unloading and loading bunkers of the central processing plant of the Angren site. The main hypotheses and conclusions. The work carried out, the main factors 183 ISSN 2224-5278 6.2024 affecting the integrity of the belt were identified: the tensile strength of the main belt when unloading rock by the unloading and loading hopper of the Central Processing Plant at various belt speed parameters. Originality. The purpose of this study is computer simulation of the CPU operation process based on the program “Ansys”. Practical significance. The calculation methods used in this study using the finite element method based on the Ansys program can be used to determine the causes of belt conveyor gusts during its operation in various production conditions, when choosing the optimal technical parameters of structures: the height of the production hopper, the speed of the conveyor belt, its angle of inclination and the material of the belt itself

В данной статье рассматривается проблема оптимизации пусковых режимов технологических машин с тяжелым ротором, актуальная для различных отраслей промышленности, включая горно-металлургический комплекс. Предложено использование пневматического пуско-вспомогательного устройства на базе сильфонных пневмобаллонов с храповым механизмом для облегчения пуска таких машин и снижения пусковых токов. Описана конструкция экспериментального стенда, имитирующего работу шаровой мельницы и приведена методика проведения исследований. Показано, что предварительная работа предложенного пневматического пуско-вспомогательного устройства в пошаговом режиме, без включения основного двигателя, существенно снижает пиковые значения пускового тока. Определено влияние давления в пневмосистеме на эффективность пуска, установлено, что увеличение давления приводит к дальнейшему снижению пускового тока. Определены оптимальные параметры работы предложенного устройства (положение конечного выключателя, давление сжатого воздуха), обеспечивающие минимальные пусковые нагрузки на штатный привод. Сделан вывод о перспективности использования предложенного устройства для повышения надежности, энергоэффективности и снижения эксплуатационных расходов на предприятиях, использующих технологические машины с тяжелым ротором.

This study proposes a novel computational method, employing the integral dynamics of multibody systems to simulate the transverse vibrations of the rotor in a cantilever-type centrifugal pump. This method was applied to the kinematic assembly of the rotor and its supports, with the latter modeled as springs possessing stiffness and damping properties equivalent to those of real bearings supporting the shaft in an actual design. To investigate transverse vibrations within the system, three key observation points were defined—at the locations of the left and right bearings, as well as at the rotor’s center of mass—to allow for a thorough dynamic analysis. Additionally, the influence of motor rotational speed and the impeller’s eccentricity on the transverse vibrations of the supports and the shaft was examined. The results have revealed that transverse vibrations significantly affect the system’s dynamics at lower rotational speeds, leading to the classification of the shaft as flexible. As the rotational speed increases, the system exhibits enhanced dynamic stability. Furthermore, it was found that for impellers with a diameter less than 300 mm, the unbalanced forces are negligible and can be disregarded in pump design. To reduce vibration levels, an elastic damping ring was selected and incorporated into the system. This novel method provides an effective tool for analyzing the transverse vibrations of centrifugal pump rotors and for optimizing vibration mitigation strategies.

Introduction. This study focuses on enhancing the energy efficiency, operational stability, and ecological sustainability of screw compressor systems widely used in industrial and mining enterprises. Despite significant progress in compressor modernization, challenges remain in adapting operating modes to variable loads, harsh climatic conditions, and high production demands. This work introduces an integrated approach combining experimental testing and mathematical modeling to develop optimized operating modes based on frequency and vector control of induction motor drives. Methods. The methodology combines laboratory experiments on an industrial screw compressor with numerical simulations of drive dynamics in d–q coordinates. Comparative tests were carried out under scalar and vector control modes using precision measurement equipment for electrical, mechanical, and thermal parameters. Statistical analysis, including averaging and confidence interval estimation, was applied to ensure the reliability of results. Additional simulations extended the analysis to scenarios difficult to reproduce experimentally, such as variable load cycles and fluctuating ambient conditions. Results. The findings demonstrate that vector control reduces starting currents by more than 50%, shortens acceleration time by 25%, and lowers bearing and winding temperatures by up to 9 °C compared to scalar control. Specific energy consumption decreased by 7–14% depending on the load profile, while overall system efficiency improved from 77.9 to 82.6%. Vibration levels during startup were nearly halved, and long-term stability under fluctuating load conditions was significantly enhanced. Calculations further showed that annual energy savings can reach up to 18 MWh per unit, resulting in notable cost reductions and extended equipment lifespan. Conclusions. The proposed approach demonstrates the effectiveness of integrating vector-controlled frequency drives into screw compressor systems, ensuring higher energy efficiency, reduced mechanical stress, and improved reliability. The results provide practical recommendations for industrial modernization projects, offering both economic and ecological benefits. The methodology is particularly relevant for mining enterprises with variable demand profiles and contributes to advancing sustainable industrial development in line with Industry 4.0 principles. © 2025, North Caucasian Institute of Mining and Metallurgy, State Technological University. All rights reserved.

As high-grade gold-bearing ore reserves rapidly become depleted, there is a growing shift towards processing lower-grade refractory ores. These ores contain gold that is finely dispersed, making it more challenging to extract. Gravity beneficiation is a common initial processing method used for these ores. However, due to the extremely small size of the gold particles, significant amounts of gold are lost during this process. This study explores methods to improve gravity beneficiation of refractory gold-bearing ores from the Vasilkovskoye deposit. Physicochemical and particle size distribution analyses have shown that gold particles in the ore samples are very small, ranging from 0.01 mm to 0.074 mm in size. Most of these particles are either dust-like or flaky and are smaller than 0.074 mm. In order to optimize the recovery of fine particles of heavy native gold and gold-bearing minerals, the design of the centrifugal hydroconcentrator was refined and a closed-cycle multi-stage concentration process was developed, which improved the recovery of gold from the Vasilkovskoye deposit ore to 56.7 %. Comparative concentration experiments for various gold-bearing ores, including tailings and waste from several processing plants, have demonstrated that the newly developed gravity beneficiation technology can improve gold concentration efficiency by a factor of 2.38. This advanced technology enables the almost complete recovery of gold particles up to 0.074 mm in size and improves the recovery of very fine, dust-like, plate-like, and flaky gold particles by approximately 15–20 %. The resulting concentrate grades meet the current requirements of gold plants.

Reliable and energy-efficient capacity control in high-pressure single-rotor screw compressors requires precise regulation of adjustable ring mechanisms operating under combined gas and thermal loading. Thermo-mechanical deformation, friction-induced torque demand, and stress concentration near discharge windows significantly influence structural integrity, clearance stability, and actuation performance. This study presents an integrated thermo-structural and analytical investigation of a regulating ring system with a hydraulic wedge-groove drive concept. Three groups of geometric variants (nine configurations total) were analyzed using coupled Steady-State Thermal and Static Structural finite element modeling in ANSYS 19.2. Thermal asymmetry between suction (22 °C) and discharge (120 °C) regions produced peak thermally induced deformation of 0.17–0.18 mm, consuming up to 60–70% of nominal operating clearance. Neglecting thermal effects underestimated peak thermally induced structural deformation of the regulating ring by 12–15%. Among the configurations, variant 2b provided the most balanced response, reducing peak equivalent stress by 12–15% and required actuation torque by 8–11%. An analytical model for friction torque and driving force was derived based on distributed contact pressure. The results reveal quadratic sensitivity of torque to contact radius and strong dependence on groove geometry. The proposed framework supports reliable clearance design and efficient actuation in heavy-duty rotating machinery.