Tạp chí của Hội Khoa học và Công nghệ Mỏ Việt Nam
Application of Sentinel-5P Satellite Data for Determining Atmospheric SO₂ Concentrations in Lao Cai Province
Lao Cai is a locality experiencing rapid socio-economic development, particularly in the Tang Loong industrial zone, where numerous metallurgical and chemical facilities, as well as intensive transport and heavy industrial activities, are concentrated. These activities have increased pressure on local air quality, adversely affecting the living environment of residents. This paper presents the results of applying Sentinel-5P satellite data from the TROPOMI sensor to analyze atmospheric SO₂ concentrations in Lao Cai province during the period 2019–2024. Data processing was conducted on the Google Earth Engine (GEE) cloud computing platform and subsequently compiled into quarterly and annual maps of SO₂ concentration distribution. The results reveal clear spatial and temporal variations in SO₂ concentrations across Lao Cai. This information provides an objective and effective basis for air quality management and monitoring in the study area.
VENTILATION, SAFETY AND ENVIRONMENTAL PROTECTION
Study on the Calculation and Selection of Hydraulic Cylinders for Radial Gate Hoisting System of Nui Ngang Reservoir, Quang Ngai Province
Currently, the demand for lifting equipment used across various economic sectors in Vietnam is very high, especially in the fields of hydropower and irrigation. According to statistics, Vietnam currently has 385 operating hydropower plants with more than 600 hydropower reservoirs. The irrigation sector manages and operates over 6,750 reservoirs of different capacities and tens of thousands of gates (including vertical lift gates and radial gates) used for water regulation. To operate these gates, lifting devices such as hydraulic cylinders, hoists, or screw jacks may be employed. Nui Ngang Reservoir in Quang Ngai Province is one of the major irrigation reservoirs in Ba To, a mountainous district. It is the third-largest reservoir in the province, after Nuoc Trong and Liet Son reservoirs. The reservoir has been in operation since 1997, with a storage capacity of over 19 million cubic meters of water. For water regulation, the Nui Ngang Reservoir uses a hydraulic system with three radial gates, each sized B×H = (8×5) m, and each gate is operated by two hydraulic cylinders with a lifting capacity of 25.5 tons. After nearly 30 years of operation, the hydraulic cylinder system has deteriorated, requiring research and selection of modern replacement equipment to improve operational efficiency and proactively respond to increasingly complex climate change conditions.
MECHANICAL ENGINEERING, ELECTRICITY- ELECTRONICS - AUTOMATION
Study on the Effect of Cutting Parameters on Surface Quality and Cutting Force in Turning SKD11 Alloy Steel on CNC Lathe
SKD11 steel is a high-alloy tool steel, widely used in die and mold manufacturing due to its superior hardness and wear resistance. However, machining SKD11 steel after heat treatment (hard turning) presents many challenges because of the high cutting forces and elevated cutting temperatures. This paper presents an experimental study to evaluate the effects of cutting parameters, including cutting speed v_c, feed rate f_z, and depth of cut a_p, on surface roughness (R_a) and spindle load (Load SPL) during CNC turning using Sumitomo carbide inserts. Using the Taguchi experimental design method with an L_9 orthogonal array, the analysis of variance (ANOVA) results shows that the feed rate f_z is the most dominant factor affecting surface roughness, with a contribution of 99.60%. Meanwhile, the depth of cut a_p has the greatest influence on spindle load, with a contribution of 62.76%. The study successfully developed second-order regression equations with high reliability (R^2>96%). The optimal parameter set was determined as v_c=130 m/min, f_z=0.12 mm/rev, and a_p=1.0 mm, enabling the achievement of a surface quality comparable to fine grinding (R_a=0.642 μm) while still ensuring safe machine loading.
Design Calculation and Strength Testing of Explosion-Proof Electric Gate Valve DN300 under High Pressure in Underground Mining
This paper presents the results of a design, calculation, and durability simulation study for a DN300 explosion-proof electric gate valve, used in drainage pumping systems in underground coal mines with harsh working conditions. The study focuses on determining optimal geometric parameters and selecting SUS 304 stainless steel material to resist corrosion in acidic water environments. Using analytical calculation combined with simulation, the authors determined the required valve disc thickness to be 110 mm and the valve cover thickness to be 12 mm to withstand a working pressure of 6.4 MPa. Simulation results show that the stress and displacement of the valve body are within permissible limits (maximum displacement 0.148 mm), ensuring reliability and explosion-proof safety according to current TCVN and QCVN standards.
Study on Nonlinear Dynamic Characteristics of a Two-Stage Planetary Gearbox Used in Mine Hoists
Planetary gearboxes are widely applied in mine hoists due to their high torque transmission capability, compact structure, and high efficiency. However, under actual operating conditions characterized by heavy loads and variable working regimes, planetary drive systems are strongly affected by nonlinear factors, leading to complex vibrations and adversely impacting system stability, durability, and reliability. In this study, a two-stage planetary drive system of a JK2.5×2.0 mine hoisting gearbox is selected and modeled using 3D CAD software (Inventor, SolidWorks). Subsequently, a dynamic model of the transmission system is established based on a multibody dynamics CAE platform (ANSYS Workbench) to investigate the dynamic behavior of the system. The impact dynamics problem is solved using the LS-DYNA solver within a nonlinear dynamic framework, enabling accurate simulation of contact–separation processes, sliding–rolling behavior, impulse transmission, and short-time stress wave propagation. Simulation results indicate that impact events generate high contact force peaks and significant dynamic stresses at several characteristic meshing pairs. The vibration amplitude increases markedly with impact intensity and backlash magnitude, resulting in a high risk of stress concentration and premature damage at the gear tooth root and contact surfaces. Moreover, the dynamic simulation reveals that meshing impacts between the second-stage planetary gears and the ring gear constitute the primary source of vibration. In practical applications, gear meshing impacts can be mitigated by selecting appropriate lubrication methods. This study provides a scientific basis for structural parameter selection, optimal design of backlash and system stiffness, as well as the development of damping strategies to enhance the dynamic stability of planetary gearboxes used in mine hoisting winch systems.
Determination of Selected Parameters of a Mobile Saw in an SVP Hot-Rolled Steel Production Line for Mine Supports
According to the current coal industry development strategy, the majority of coal production comes from underground mines. Deep mining operations require advanced technology and support equipment, thus the demand for steel SVP (CBΠ) and certain types of U, I, and L-shaped steel is increasing. To meet this demand, Vinacomin Machinery Manufacturing Joint Stock Company (VMC) has invested in a modern steel rolling line with a capacity of approximately 80,000 tons/year. In the steel rolling line, steel billets are fed into a furnace at temperatures ranging from 1050°C to 1150°C, then passed through a shaping die to create the preliminary shape of the part. After the shaping process, the part, at a temperature of approximately 750°C, is cut into standard lengths by a sawing machine. Finally, the part is sent to a cooling area before being straightened by a straightening machine to ensure the desired dimensions and quality. In this study, the authors focused on the process of sawing the parts into segments after the rolling stage. The research content introduced the structure, working principle, and presented some theoretical foundations for calculating and designing the machine. In addition, the study has shown the relationship between the parameters in machine operation (cutting depth, feed rate, cutting speed, etc.). Based on this, a 3D sawing machine structure is constructed, and the optimal design of parts and sub-assemblies is calculated using NX12 software. The research results provide a reasonable machine structure and parameter set, which can be used as a reference for the design calculations of mobile sawing machines.
Study on the Technology for Constructing Thick Wet-Mix Shotcrete Linings in Underground Coal Mines in the Quang Ninh Region
The technology of constructing the tunnel casing by spraying wet concrete with large thickness is one of the advanced solutions, which has been widely deployed in countries with developed mining industries such as Germany, the US, Russia, China... as well as being effectively applied in many large underground works in Vietnam in the fields of transportation, hydropower and irrigation. This technology not only contributes to improving the level of mechanization in tunnel construction but also significantly improves the quality of the casing structure, increases stability and safety, while reducing construction costs, shortening construction time and expanding the application capability in complex geological conditions. Within the framework of the article, the group of authors conducted an overview study on the process of formation, development and practical application of the technology of spraying wet concrete with large thickness in the world and in Vietnam. On that basis, the article proposes a number of technological diagrams and synchronized equipment suitable for the conditions of underground coal mines in Quang Ninh area.
Study on stability of the GKQD-2000/1.6/2.4 Transitional Frame Hydraulic Support at the Longwall Junction Using Discontinuous Environment Simulation
The paper presents the results of verification and analysis of the operational stability of the GKQD-2000/1.6/2.4 GKQD-2000/1.6/2.4 Transitional Frame Hydraulic Support at the intersection area of the mining roadway, based on discrete element environment simulation (UDEC).The simulation results demonstrate the successful construction of an interaction model between the frame support and the surrounding rock mass in the mining roadway, continuously aligned with the excavation progress. Stress redistribution and rock mass displacement phenomena were realistically reproduced. The coal face and the frame support exhibit stable structural behavior, ensuring safety within the permissible mining limits. Detailed evaluation results indicate that the variation trends of support force and moment on the hydraulic frame are consistent with the evolution of mine pressure and rock mass displacement under normal mining conditions prior to the collapse of the main roof. In the context of limited monitoring of mine pressure in the roadway and restricted experimental space for support operation, the numerical model analysis of frame stability provides initial confirmation of support safety. Moreover, it serves as a foundation for improving frame characteristics to better adapt to extreme roof displacement phenomena in subsequent studies.
Training of mining mechanical engineers at the University of Mining and Geology: Directions for innovation in the period of scientific and technological breakthrough
In the context of the Fourth Industrial Revolution (Industry 4.0) and the rapid development of artificial intelligence (AI), the training of mining mechanical engineers is facing a strong demand for innovation to meet the breakthroughs in science and technology. Building upon 60 years of development of the mining mechanical engineering sector at the Department of Industrial Machinery and Equipment, Faculty of Mechanical and Electrical Engineering, Hanoi University of Mining and Geology, this paper focuses on assessing the current state of training, analyzing existing problems, challenges, and requirements. Simultaneously, it synthesizes advanced engineering training trends worldwide, thereby proposing directions for reforming the mining mechanical engineering training program to align with Resolution 57 and the trends of modern scientific and technological development.
Applying Exploratory Factor Analysis (EFA) to Identify Factors Affecting Business Performance at Vinacomin- Mao Khe Coal Company
Business performance is an important economic indicator and a valuable source of information for managerial decisions as well as scientific research. Based on a review of studies on factors influencing business performance, this paper employs a quantitative research approach to identify the determinants of business performance at Mao Khe Coal Company – Vinacomin. From the perspective of material flow dynamics, business performance is formed through the stages of production preparation, production, consumption, and outsourcing. The research team used a five-point Likert scale to design a survey questionnaire. After eliminating invalid responses, the collected data were analyzed using Cronbach’s Alpha reliability testing, Exploratory Factor Analysis (EFA), correlation analysis, and regression analysis with SPSS 27 software. The results reveal three groups of factors influencing business performance at Mao Khe Coal Company – Vinacomin, corresponding to production, consumption, and outsourcing activities. The regression analysis is statistically significant at the 0,05 level and explains 68,2% of the variance in business performance. Among these, the production-related factors have the strongest impact, with a standardized coefficient of 0,554, followed by consumption and outsourcing factors.
Petrovietnam’s Growth Model Transformation Based on Science, Technology, Innovation and Digital Transformation
In the context of global upheaval and a strong trend toward energy transition, transforming the growth model has become an urgent requirement for the Vietnam National Industry - Energy Group (PetroVietnam). The traditional resource-based growth model is increasingly revealing its limitations. This paper analyzes PetroVietnam’s strategic shift toward a new growth model, driven by core pillars: Science and Technology (S&T), Innovation, and Digital Transformation. The foundation for this transformation is the "Strategy for Science, Technology, and Innovation to 2030, with Orientation to 2050" currently under development. The paper focuses on key strategic technology directions that PetroVietnam intends to prioritize for development and application, including: optimization of current operations through digital technologies and AI; development of clean energy and green chemicals; decarbonization technologies and circular economy practices; and advanced energy and material technologies. Additionally, the paper introduces systemic implementation solutions being proposed, particularly the development of the “Petrovietnam Innovation Ecosystem (PIVOT),” to ensure a successful transformation. This approach aims to enhance PetroVietnam’s competitiveness and secure sustainable development in the evolving energy landscape.
Determination of the Optimal Operating Mode of Main Surface Fans during Non-Working Days to Save Electricity at Khe Cham I Coal Mine, TKV- Ha Long Coal Company
According to current regulations, underground coal mines must be ventilated continuously, day and night. This means that both the main surface fans and the auxiliary underground fans must operate 24 hours a day. However, in practice, underground coal mines normally do not operate on public holidays, Tet holidays, or Sundays. On these non-working days, no production activities take place in the mine. Consequently, factors that pollute the air environment and pose risks of gas explosions or coal dust explosions are greatly reduced compared to those in working days. This practice indicates that the main fans do not necessarily need to operate in the same mode as on regular working days to supply fresh air into the mine. The question, therefore, is what operating mode of main fans should be implemented to contribute to reducing coal production costs through electricity savings. This paper presents the potential for reducing electricity costs by determining the appropriate operating mode of the main fans during non-working days in coal mines.
Evaluation of the Applicability of Fuel Cell - Battery Hybrid Electric Trucks for Serving Open-Pit Mining
As the mining industry moves towards more sustainable development, mining corporations are looking for low-carbon energy sources for trucks. Replacing diesel engines in mining trucks with electric batteries or fuel cells has been studied. Each system has its own advantages and disadvantages. Recently, there have been studies in the world applying hybrid power systems between hydrogen fuel cells and electric batteries for mining trucks. Fuel cells combine hydrogen and oxygen to generate electricity, electric batteries store electricity for use when sudden power increases are needed and regenerate energy when braking. When replacing diesel engines, the challenge is to improve trucks originally designed to use diesel engines into trucks using hybrid fuel cells and electric batteries. This article provides initial assessments of some indicators of large-capacity mining trucks using diesel engines, converted to fuel cell - battery hybrid electric truck, as a basis for choosing environmentally friendly mining truck power systems.
Strength Verification Calculation of the Explosion-Proof Vacuum Circuit Breaker Enclosure THCDPN-660 (1140) for Underground Coal Mines
In the design of electrical equipment intended for use in underground coal mines where explosive gas and dust atmospheres may be present, the flameproof enclosure plays a critical role. The enclosure shall comply with all applicable requirements of type of protection “d” (flameproof enclosure) in accordance with IEC 60079 and the corresponding Vietnamese standard TCVN 7079. Therefore, the design process requires conformity with enclosure construction requirements in combination with mechanical strength verification calculations. This paper presents the technical requirements for the flameproof enclosure of a vacuum switch, together with the methodology and results of strength verification performed during the design stage. The research methods, design procedure, and results presented in this paper can be generally applied to the design of flameproof enclosures for electrical equipment intended for use in underground coal mines.
Study on the Use of Tailings Sludge from the Ta Phoi Copper Concentration Plant as a Replacement for Natural Sand in the Production of Cement-Free Green Concrete
This paper presents the experimental results on the use of waste mud from the Ta Phoi Copper Processing Plant as a partial replacement for natural fine aggregates in the production of green concrete without cement. The plant generates approximately 60,000 m³ of waste mud and tailings per month, posing significant challenges to storage capacity and environmental safety. The study follows current Vietnamese standards to evaluate the workability and compressive strength of green concrete mixtures containing 0÷30% waste mud. The resulting mixtures exhibited good workability with slump values ranging from 14.5 to 20.0 cm, stable bulk densities, and 28-day compressive strengths exceeding 40 MPa. The optimal mixture containing 10% waste mud achieved the highest compressive strength of 55.5 MPa. These findings demonstrate the potential of waste mud to function as an artificial fine aggregate, offering a sustainable solution to reduce natural sand consumption, manage industrial waste, and promote eco-friendly construction materials..
Innovation in Management and Production Organization through Artificial Intelligence (AI) Application in Underground Coal Mines in Quang Ninh Region
Artificial Intelligence (AI) is emerging as a key technology to address systemic challenges in the mining industry, ranging from operational optimization and cost reduction to enhancing worker safety and environmental protection. Despite its proven potential, the large-scale adoption of AI in underground coal mining remains limited due to high investment costs, lack of supportive policy frameworks, and the industry’s cautious approach to technological transformation. Overcoming these barriers requires close collaboration between enterprises, regulatory bodies, and academic institutions, alongside the development of a digitally skilled workforce and the promotion of a responsible innovation culture. In the context of underground coal mines in Quang Ninh – the largest coal-producing region in Vietnam – management models remain dominated by traditional approaches, manual operations, and limited automation. This study analyzes the current status of management and production organization in the region’s coal mining enterprises. Based on the findings, the paper proposes an AI-based management and production model aimed at improving productivity, ensuring occupational safety, and advancing sustainable development. Furthermore, a practical roadmap for AI implementation in underground coal mines of Quang Ninh is introduced, tailored to the specific conditions of local enterprises.
Research on Selecting Appropriate Drilling and Blasting Methods and Parameters for Open-Pit Coal Mines in Quang Ninh Area of TKV
The paper presents a study on selecting appropriate drilling and blasting methods and parameters for open-pit coal mines in Quang Ninh area of TKV, and the results of experimental blasting at Cao Son coal mine. The results of the research and testing show that although the explosive index increased from 7.5 ÷ 21.1% compared to the current standard depending on each type of excavator bucket capacity and the physical and mechanical properties of soil and rock, the productivity of the loading and unloading transport combination was significantly improved, the excavator's loading cycle time was reduced by an average of 19.74%, the excavator's productivity increased by an average of 21.86%; the productivity of the car increased from 5 ÷ 8.33% compared to the standard; the volume of drilling and blasting for the second time was reduced. The calculation results in Cao Son mine conditions show that the average cost of removing soil and rock will decrease by 542 VND/m3 when applying the proposed drilling and blasting parameters.
A Proposed Method for Determining Water Inflow Sources into the 11-1.10 Longwall at Levels -175/-180 in Zone III of Seam 11, Vinacomin – Ha Lam Coal JSC
The Ha Lam Coal Mine, operated by Ha Lam Coal Joint Stock Company – Vinacomin, has been exploited using both open-pit and underground mining methods. After the completion of surface mining, the spoil dumps have been reclaimed and graded to elevations equal to or higher than the regional drainage level. During underground extraction at longwall face 11-1.10 (level −175/−180) in Zone III of Seam 11, located beneath the waste dump of Seam 14 in the western field, a sudden water inrush occurred, disrupting production activities. This study investigates the source of the inflowing water through hydrogeological analysis and field data interpretation. The results reveal a potential hydraulic connection between the overlying spoil dump and the underlying coal seam, which led to the incident. Based on these findings, technical measures are proposed to prevent similar events and to improve the safety and stability of mining operations in the remaining reserves.
Study on establishing a set of criteria for identifying rare earth elements in weathering crusts
Ion-adsorption type rare earth element (REE) deposits in weathering crusts represent a strategic class of mineral resources with high economic value and relatively simple mining and processing technologies. These deposits have been extensively discovered and exploited in China, Myanmar, and more recently in Vietnam. This paper presents a framework of six groups of geological–environmental identification criteria to support the investigation, exploration, and assessment of the potential of REE deposits in weathered crusts, including: (1) Characteristics of parent rocks, (2) Topography and geomorphology, (3) Chemical alteration indices, (4) Climatic conditions, (5) Composition of REE-adsorbing clay minerals, and (6) Forms of REE occurrence and field identification methods. Through a synthesis of international literature and field data from Vietnam, this study emphasizes the controlling roles of REE-enriched felsic parent rocks, long-term tropical to subtropical humid climates, gentle hill topography, deep chemical weathering, and the presence of clay minerals with high cation exchange capacities (kaolinite, halloysite, illite, etc.). In addition, the paper proposes several supplementary criteria, such as the thickness of the weathering profile, HREE/LREE ratio, and Ce/Ce* anomaly, to assist in the rapid evaluation of orebody potential. These findings contribute to the development of a standardized identification framework for REE resources in Vietnam, in the context of increasing global demand for rare earth elements.
GEOMECHANICS, GEOMATICS, GEOLOGY, GEODESY
Application of Machine learning and Kriging methods in the geological investigation of ion-adsorption rare earth deposits
Ion-adsorption type rare earth element (REE) deposits are of strategic significance and commonly occur within deeply weathered profiles in tropical humid regions. However, evaluating their resource potential and delineating prospective zones remain challenging due to complex spatial variability and limited sampling data. In this study, modern techniques including geostatistical interpolation (Kriging) and machine learning models such as Random Forest (RF) and Support Vector Machine (SVM) were integrated to analyze geochemical data and model the spatial distribution of REE across a 10 km² study area. Based on 30 field sampling points and a simulated grid of 10,000 locations, the RF and SVM models were trained to classify prospective zones using REE_sum concentrations. The classification results revealed that the central area exhibited the highest probability of REE enrichment, consistently identified by both RF and SVM models. Kriging interpolation (on a log-transformed scale) showed a clear geochemical gradient with REE concentrations decreasing outward from the center, demonstrating strong spatial continuity. The study area was further subdivided into 500 m × 500 m blocks for resource estimation, resulting in a total calculated resource of approximately 11,300 tonnes of REE, predominantly concentrated in the central blocks. A 3D block model was constructed to support spatial visualization and aid in future mine planning. This study demonstrates the effectiveness of integrating Kriging and machine learning models for spatial modeling and resource assessment of ion-adsorption rare earth deposits. Beyond its methodological contribution, the study provides scientific and practical significance by establishing a data-driven workflow applicable to similar REE_sum-based investigations in Vietnam, supporting strategic resource planning.
Ứng dụng phương pháp giảm cường độ cắt trong nghiên cứu và xác định vùng biến dạng của mái dốc
Quá trình thay đổi giá trị thông số cường độ chống cắt của đất tạo nên vùng biến dạng dẻo của mái dốc. Tại trạng thái sau biến dạng, vật liệu sẽ thay đổi và không còn ở trạng thái nguyên dạng như trước, các liên kết trong vật liệu bị phá vỡ và kết cấu bị phá hủy. Trong bài báo này, phương pháp giảm cường độ cắt được sử dụng để xác định cơ chế hình thành, quá trình phát triển, khả năng dịch chuyển cũng như vị trí chính xác của vùng biến dạng dẻo trên bề mặt trượt của mái dốc. Mô hình mái dốc 3D được xây dựng, phân tích, tính toán hệ số an toàn cũng như xác định vùng biến dạng dẻo gây nguy cơ trượt lở mái dốc bằng phần mềm Midas GTS NX tích hợp phương pháp giảm sức chống cắt.
Estimation of geological coal reserve by structure modeling for Vinacomin coal seams
The structure of coal seams in Vietnam is quite complex with tectonic disturbances and inseam rock partings. Determining the geological structure, calculating reserves and especially the geological reserves of coal seams is a common but rather difficult task for mining engineers. The traditional method in Vietnam is linear interpolation and calculating reserves by parallel cross-sections. But now, with the support of computers, the modeling method is being widely applied, and moreover, it also helps to accurately describe the structure of the coal seam and eliminate the rockpartings located between the roofs and floors in the seams, which is very necessary for calculating coal reserves. At the same time, new criteria for coal reserves have also been introduced, such as T, T1, T2. This newly applied method of calculating coal reserves not only increases the accuracy, but also shortens the time and even increases the calculated coal volume compared to the traditional method, has many scientific and practical meanings, and can be effectively applied to geological and surveying works such as calculating geological reserves and calculating mining excavated volume. The main content of the paper is to introduce the method of calculating reserves by combining structural modeling and thickness of coal seam. This method is applied to calculate all major coal seams in large open-pit mines of Vinacomin, but the typical case study presented in the paper is the case of Caoson and Hatu mines, using data from boreholes in Vinacomin's geological exploratory reports. In order to have good results of reserve estimation, the article also introduces the creation of relational geological databases of coal deposits for mines. The modeling results demonstrate the effectiveness of these PC applied works, including establishment of coal seam structural maps such as elevation isolines of roof, floor and thickness of coal seams, as wel as tectonic zone planes. These modeling results can be served as the basis for mine design, mine planning, mine scheduling, mine optimization and economic efficiency calculation... on computers in a continuous and intergrated way.
Design of a vacuum contact pair for 660/1140 V switchgears used in underground mine power networks
The vacuum contact pair located in interruption chamber (The vacuum contact pair) is the core component of switchgears used in mining power systems. The design and evaluation process of the vacuum contact pair are often influenced by empirical parameters. With the advancement of modern technology, the application of numerical simulation tools in vacuum contact pair design has significantly improved reliability and shortened the design time. This paper presents the analysis and design of a vacuum contact pair using the finite element method (FEM) implemented in ANSYS software. Experimental validation was conducted on a physical prototype to verify the theoretical results. The findings of this study provide a solid scientific basis for domestic manufacturers to develop and produce vacuum switchgears, contributing to the replacement of imported equipment for mining power systems.
Analysis of electron transport coefficients in gas mixtures for plasma discharge in emiconductor etching- Atrend in mining electrical equipment manufacturing
This study presents the calculation and analysis of electron transport coefficients in gas mixtures composed of argon (Ar), molecular fluorine (F2), and nitrogen (N2), with a focus on their relevance to gas discharge applications. Using the BOLSIG+ Boltzmann solver and well-established electron collision cross-section data, key parameters such as mobility, diffusion coefficients, and ionization coefficients were evaluated across a range of reduced electric fields (E/N) and mixture ratios. These data serve as critical input for the modeling and optimization of low-temperature plasma discharges, particularly in applications such as reactive ion etching and thin film deposition using inductively coupled plasma systems.
Experimental investigation on the effect of surface micro-texture on friction–wear characteristics and operational performance of swash plate axial piston pump
In the context of the increasingly urgent demand for enhancing the operational efficiency and extending the service life of mechanical–hydraulic equipment, research into solutions that minimize friction- and wear-induced losses while improving lubrication performance in friction pairs operating under high load, high pressure, and high-speed conditions has become essential. Globally, the application of surface micro-texturing to friction pairs has emerged as a breakthrough in the field of tribology. Micro-textures such as micro-grooves, dimples, protrusions, and other specialized geometries have demonstrated a remarkable ability to improve lubrication effectiveness, reduce friction coefficients, and mitigate wear. These micro-texture designs have been successfully applied in several countries, including the United States, Austria, Turkey, Russia, and particularly China, achieving reductions in friction coefficient of up to 20%, extending component lifespan by 15%–35%, while also saving energy and lowering maintenance costs. This study presents an experimental investigation evaluating the practical effectiveness of micro-textures in improving the friction–wear performance and lubrication characteristics of a swash plate axial piston pump. The results contribute to clarifying the role of surface micro-texturing in reducing friction and wear, controlling lubrication regimes, and enhancing the overall efficiency of hydraulic equipment. The findings not only provide a scientific basis for applying micro-texture technology in hydraulic devices but also reveal its potential for deployment in mechanical and energy systems operating under harsh conditions, particularly in Vietnam’s mining and heavy industries.
Mechanical performance of concrete incorporating fluidized catalytic cracking residue from the petrochemical industry as a supplementary cementitious material
The increasing demand for sustainable construction materials has highlighted the need to reduce the environmental footprint of cement production. This study investigates the reuse of petrochemical residue fluidized catalytic cracking (RFCC) waste as a supplementary cementitious material (SCM) in concrete. RFCC was subjected to two activation methods: high-temperature treatment at 800, 1000, and 1200 °C, and mechanical grinding to enhance pozzolanic activity. Concrete mixtures were prepared with cement replacement levels ranging from 10% to 50% by mass. Fresh properties, including workability and setting time, and hardened mechanical properties such as compressive strength, flexural strength, and elastic modulus, were evaluated at 28 days. Results show that RFCC reduces slump and shortens the setting time of concrete mixtures. At 50% cement replacement, compressive and flexural strengths decreased by up to 45%. However, thermal activation at 1000–1200 °C significantly improved compressive and flexural strengths as well as elastic modulus by 10–20% compared to untreated RFCC. Ground RFCC showed lower early-age strength at 10% replacement but outperformed heat-treated RFCC at higher replacement levels (20–50%). The findings demonstrate that properly treated RFCC waste can replace up to 30% of cement without compromising mechanical performance, offering a viable route for cost reduction, carbon emission mitigation, and sustainable concrete production.
Finite element and fictitious component methods for solving the poisson equation in a rectangular domain
This study presents a novel hybrid numerical framework for solving the Poisson equation ∇²u = f in a unit square domain Ω, discretized into a uniform 14×14 coarse grid, with the computational domain encompassing a triangular subregion defined by vertices (0,0), (0,1), and (1,1). The methodology integrates the Finite Element Method (FEM) for triangulation—refining each grid cell into two linear triangular elements along a diagonal—with the Fictitious Component Method (FCM) to embed the irregular domain into a fictitious square, enhancing iterative efficiency. A stiffness matrix is assembled via FEM weak formulation, modified by FCM penalty terms, and solved using Richardson iteration with an optimal parameter ω ≈ 2/( + ), where and are extreme non-zero eigenvalues of the system matrix. Numerical simulations across mesh refinements (3,249 to 201,601 nodes) demonstrate rapid convergence in 39 iterations to ||r|| < , achieving O(h²) accuracy ( < 0.00015) and linear time scaling (~1.2 ms/node). Compared to pure FEM, the hybrid reduces iterations by 54% and computation time by 40% on fine meshes, underscoring its novelty in preconditioning ill-conditioned systems for irregular geometries. This framework offers significant potential in geomechanics and mining engineering, enabling efficient modeling of stress-strain fields and rock deformation around tunnels, with broader applicability to nonlinear and 3D problems.
Research on wall cutting using a mixed hydraulic-directed blasting method in mining technology without leaving protective pillars
Controlling the rock mass's state to relieve mine pressure on the longitudinal haulage roadway in the longwall pressure zone is the most important and complex technological stage in the combination of support and maintenance solutions for reusing the longitudinal haulage roadway under non-pillar mining schemes. Directional roof-cutting blasting has been widely applied in China and the Russian Federation. Due to the the wide variability in physico-mechanical properties and structural characteristics of roof strata, it is difficult to form an ideal fracture surface (weakly connected surface) that allows the roof to cave and break as expected. In practice, combined methods are commonly employed: combining the method of concentrated blasting to cut the rock face with the method of blasting to break up the rock mass; combining the method of directional hydraulic blasting with the method of blasting to break up the rock mass. These approaches result in a very large volume of drilling and blasting work, especially in the case of mining thick seams according to the longwall mining scheme - lowering the roof to recover coal and the rock face is of a stable, non-collapsible type. Based on theoretical research and practical application of methods to weaken the rock mass, the authors propose a technology for roof cutting using a combined hydraulic-directional blasting method applied to the conditions of mining thick seams and some experimental results of the technology at the IV-9-17 longwall haulage roadway of Ha Long Coal Company.
Numerical study on stability of retained roadway in non-pillar mining at Nam Mau coal mine
By using numerical modelling method, the study aims to better understand the geomechanical behaviours of roof strata and stability of retained roadway in the non-pillar mining method at Nam Mau coal mine. The analysis of numerical model shows that when the face is far away from the retained roadway, the mining does not cause significant impact on roadway stability. When the face approaches the roadway, the vertical stress gradually increases around the roadway. The stress reaches a peak value when the face is from 10 to 20 m away and then rapidly decreases when the roadway complete falls within the stress relief zone of longwall. In combination with the insignificant concentration of horizontal stress, the surrounding stress condition induces the roadway to deform and fail when the face approaches roadway. The study finds that the roadway is significantly affected when the face is adjacent to it. The rock mass around roadway fails up to 25 m towards the unmined area. At the end of the upper panel mining, only immediate roof caves that form a caving line of less than 70 degrees to seam floor. The strong main roof does not cave but sag downwards, causing significant load on roadway. The results in this paper can serve as fundamental knowledge for efficient design of roof cutting techniques, contributing to reducing the cost of using non-pillar mining method into Vietnam coal industry.
The urgency of applying the circular economy model in bauxite mining and processing in Tay Nguyen
The article presents an overview of environmental and resource issues in Bauxite mining and processing activities at Lam Dong Aluminum Company and Dak Nong Aluminum Company. On that basis, propose a circular economy model in Bauxite mining and processing activities in Tay Nguyen. Using specific data from the exploitation and processing of Bauxite ore of the two companies above, the report evaluates the socio-economic and environmental benefits, as well as proposes specific solutions for effective implementation. effective circular economy model for bauxite mining and processing activities in Tay Nguyen.