Search

The paper analyzes the technical and safety factors for the storage of different gaseous products (air, carbon dioxide, hydrogen, methan gas, etc.), in the eligible salt caverns from Romania, especially in the compact salt caverns created by dillution process. This new approach to research and project results, will be an important contribution to the evaluation of large-scale storage capacities in Romania and is necessary for decision-makers to consider these technologies as some of the most appropriate in terms of risks. Especially was studied the geological and lithological diagrams and colected data from the conserved salt mines in order to analyze the storage conditions. The paper analized the Slanic river area, a Trotus tributarry, where disollution method was well implemented, near Targu Ocna town, Bacau County, Romania. The mining area is located near a well-known industrial center for chemical processing, Borzesti Chemical Works, with a great interes in the gas storage facilities. The storage of different gases implies different technologies for gas compression and gas transportation, this beeing in the near future a new challenge for research for reducing greenhouse gas emissions, according to the UN 2030 Agenda for Sustainable Development.

The present paper explores the change of the harmful factors by means of full-scale numerical models. In the numerical models, the tunnel length is 400 m; the slope gradient varies within 0-9%, with a 2% step; and the heat release rate is within 5-50 MW. The outdoor air temperature on the models was assumed to be 20℃, while the pressure difference between the portals on different models varied depending on the slope, and the variation range was 50-400 Pa. The modeling results show that the propagation of the harmful factors is characterized by stabilization as demonstrated by the fact that the distance of descending propagation of the harmful factors decreases for each specific tunnel gradient and eventually shows a pronounced asymmetry with respect to the seat of fire. This confirms the preferential and pronounced ascending movement of the ventilation flow with toxic products of combustion. Thus, the worst results during the natural ventilation are expected for ascending flows. Based on the isolines of temperature, as well as the concentrations of carbon monoxide and oxygen, the gradient factor can be calculated, which can be used to design ventilation systems for engine tunnels, ensure their safe operation and save human lives during the fire.

Corrosion is a major problem in the mining industry, significantly affecting the durability and reliability of mining equipment. In order to better evaluate and understand these effects, in the first part of this study, the analysis by the finite element method of the metallic structure of the rotary arm of an ERc 1400-30/7 bucket excavator type, produced in Romania in 1985, is presented. This paper presents an analysis of the impact of corrosion on the structural integrity of mining equipment. The focus of the research is on the use of advanced spectral analysis methods and the implementation of wavelet analysis. These methods allow an increase in the degree of accuracy of the information and results obtained. The study also focused on the impact of corrosion on the natural frequencies and structural changes in mining equipment, which were evaluated based on advanced methods of structural analysis. The obtained results show that corrosion deeply affects the dynamic behaviour of the metallic structure, leading to significant changes in the dominant frequencies. It was found that the measured dominant frequencies show a tendency to increase with the increase of structural degradation, an observation that is consistent with the physical aspects of the phenomenon. [ABSTRACT FROM AUTHOR]

Jiu Valley is in an extensive transition process from an area rich in coal deposits to an area with 0 Carbon emissions. Coal mining was carried out in 14 mining perimeters arranged along the Jiu Valley. At the same time, the extraction of the useful mineral substance resulted in waste material that was stored in tailings dumps. Out of the total of 49 landfills, 25 have been greened, 15 are inactive and 9 are active. The total area occupied by them is approximately 210 ha, arranged near mining operations, in the valleys of some streams and even in the vicinity of human settlements. The paper aims to identify the potential for soil contamination due to inactive tailings dumps. [ABSTRACT FROM AUTHOR]

Coal mining is a vital industrial activity but often associated with negative environmental effects, including the accumulation of waste containing heavy metals in tailings dump. These heavy metals, such as lead, chromium, copper, zinc, cadmium, mercury, and others, pose significant risks to the environment and human health. The mobility of these heavy metals is a major concern, as they can be released into soil and water during rain or erosion processes, contaminating water sources and affecting aquatic and terrestrial life. These metals can be taken over by plants and eventually end up in the trophic chain, including in humans. The toxicity of heavy metals is well known, with these substances having harmful effects on human health. In this paper, the main ways of transferring heavy metals into environmental components and their spatial distribution from sterile holes to water and soil environment components. As a case study, the sterile Balomir hole, an inactive hole for about 9 years resulting from the exploitation of the hule from the Uricani mine located in the Jiu Valley. [ABSTRACT FROM AUTHOR]

Anthropogenic activities related to mining generate both progress and a vast amount of waste that is responsible for environmental degradation. The Jiu Valley is one of the areas of Romania where mining has affected large areas of land, used to build mines and tailings ponds. The former Coroiesti coal processing plant (CCPP) is such a location with a total area of 25 ha containing approximately 5.5 million tons of tailings. The assessment of the stability of tailings dams is extremely important from safety and environmental aspects. This study proposes a solution based on numerical methods for determining the stability of a section of the dam of a tailings pond. The model of tailings pond no. 1, compartment B, from the Coroieşti Coal Preparation was built using COMSOL Multiphysics. Two scenarios of stability analysis were conducted on a section of the tailings dam: the FOS was determined using the shear strength reduction (SSR) method for both the initial and the current state of this TP. This method is a modern alternative to the limit equilibrium method, and its implementation by COMSOL is new to our country, thus aligning this methodology with current worldwide trends and developments in the field. The results obtained proved to be in line with those calculated in the past with traditional analytical methods, proving that the safety criteria of the studied TP/TD are being met. [ABSTRACT FROM AUTHOR]

The results of numerical modeling in longitudinal ventilated sloping road tunnels are given. The slope of the tunnels varies in the range of 0-6%. The geometry of the tunnel is as follows: length: 100 m; width: 8 m; height: 6 m; area of the seat of fire: 16 m2. The seat of fire sized: 2.75x5.8x1.5 m is in the central part of the tunnel. The scenarios of development of 5, 10, 20, 30, 50 MW fires are studied in the case of positive and negative directional ventilation flows. The time of modelling was 120 seconds. The numerical problems were modelled with a volumetric grid method. The grid cell dimensions were: 0.5*0.5*0.5 m. Virtual point and volumetric measuring equipment was used to record the modeling results. The modelling used 4 groups of measuring devices that measured and recorded air velocity, temperature, and air and smoke densities. The paper discusses cases of algebraically summarizing the ventilation and fire-induced flows. Based on the results of numerical modeling, we can point out that the widely accepted indices of critical velocity and back-layering length in inclined road tunnels often give erroneous results. Therefore, in strategies for emergency ventilation, indicators such are critical velocity and back-separation should be used with caution.

Determining the risk factors of a job is a process that requires many studies. Determining risk factors is necessary to prevent accidents at work. The process of closing and greening the Lupeni Mining Exploitation is a very complex one. The closure of the mining operation is done in stages for the underground and the surface based on a closure project. When implementing the closure and greening project, all occupational safety and health regulations must be observed. As part of the process of closing and greening a mining operation, it is necessary to redo the risk factor assessment sheets with additional measures for the closure and greening of the mining operation. In this paper we intend to establish the risk factors for the miner workplace within the Lupeni Mining in the process of closure and greening.

All main and auxiliary equipment in the tunnel with an intelligent ventilation system are designed to ensure the safety. These systems “talk” and “listen” to each other, make decisions to switch on/off certain system(s) or part(s) thereof and duly inform the tunnel operator, who is authorized to the centralized control of all systems of necessity. The present article uses the numerical models to assess the efficiency of the transformable elements ensuring safe operation of the tunnels. The idea of their use is based on an artificial increase of the tunnel aerodynamic resistance by means of a flexible element, which will hamper the dissemination of combustion products, but not the movement of people through the tunnel and will help isolate clean and polluted air masses. Such resistance will be used to swiftly divide the tunnel carriageway into smaller sections what will help extinguish the fire as early as at its initial stage, prolong the evacuation time and save lives during the strong uncontrollable fires. As for the compact transformable element, it can be used in both, the operating and the planned tunnels, as it in practice does not reduce the volume of valuable underground space.

The work gives the study results for 1:10 scale physical models of the road tunnels. The tunnel slope changes from 0 to 10% with a 2% spacing. As the models show, the fire strength varies within the range of 5 to15 MW with 5 MW increments. The properties of the tunnel geometry in nature are as follows: cross-sectional area: 46.7m2, length: 120 m, width: 8.5m, height: 5.5m and width and height ratio: 1.54. The models are made of 2 mm-thick stainless-steel sheets. We studied the nature of the spread of smoke, the variation of critical velocity depending on the tunnel slope and the characteristic value of such variation - the grade correction factor. The observation over such values is done depending on the air temperature variability in the tunnel model. The measurements are made with K-type thermocouples with open and closed detectors. Maximum temperature measurement is 800°C. The thermocouples are located in the holes provided in the ceiling of the tunnel model. The distance between the holes is 5 and 10 cm what corresponds to the natural length of the tunnel of 5 and 10 m. Fire is modeled by using the natural gas. The indications of thermocouples and air and gas meters are measured simultaneously and the primary analysis and the digital data transmission are provided with a Data Taker DT85 data logger. The gained results may be used to develop ventilation and emergency management projects for transport tunnels as well as to train personnel and rescuers.

This paper studies how the activity of hydraulic excavators found in the Rosia quarry of Jiu affects the environment. For this study we chose the Caterpillar 323D L and 323 D LN hydraulic excavators. The study took place over a period of 30 days. These days we have collected data on the noise level and the level of PM 10 particles in the quarry. Caterpillar equipment not only helps to build a better world, but also helps to preserve the environment, which is so fragile today. The evolution of excavators has led to a more efficient way of working both in terms of production, costs and effects on the environment. Their efficient way of working has led to an increase in production and a decrease in the level of pollution in the Rosia Quarry area.

The studied geographical area is situated in a intramontane region situated on the Jiu River called the Jiu Valley, where the main economic activity is mining. The importance of studying this area is related to the effect of coal mining on the climate. Coal extraction in the area led to a change of atmospheric temperature due to the emissions of gases and dust that affects the environment. The use of LM75A sensors allow us to accurately read the air temperature and transmit warning messages when certain temperature intervals are exceeded.

In the article, the authors present the approach of combining energy production systems, subsystems by obtaining specific advantages, facilitating the efficient conversion of resources subject to advanced energy-thermal treatment, and solutions are proposed for the creation of a "photovoltaic - other combining resources" matrix. obtaining the generational energy mix. The paper describes the endogenous economic growth through the knowledge of hybrid technological processes, the technical and technological changes in the field of energy, the relational implications in the field and advances the proposal of a hybrid energy system based on the mix of geothermal energy resources from closed coal mines) and renewable energy resources solar. Also, the breakdown of energy/geothermal heat sources recovered from galleries and long-front abattoirs as lots of a sub-system of energy production in a hybrid energy system based on the mix of geothermal mining and renewable solar energy resources is reported. The authors conclude that the addition of the "hydrogen production" sub-system to the hybrid energy system based on the mix of fossil and renewable energy resources represents extensive conceptual and operational specific development. [ABSTRACT FROM AUTHOR]

The bucket wheel excavator (BWE) is a complex continuous digging machine, used to excavate material using a layout of buckets installed on a rotor (bucket wheel), and at the same time, using the conveyor system installed on its boom, transferring this material to the main conveyor. The bucket wheel is the operating equipment, and it rotates in the vertical plane and performs (with the boom) a pivoting movement in the horizontal plane and an ascendant – descendent movement in the vertical plane. The paper presents a new grafo-numeric method of determination of the operation power of the BWE rotor, using computer simulation in SolidWorks. The aim of using virtual models for the analysis of the operation of some components of the BWE is to reduce the specific energy consumption during cutting while maintaining the installed operation power of the rotor, to increase the excavation capacity and to improve the cutting – loading system.

The calculation of defects represents the analysis of the behavior of the energy system in short-circuits and/or phase outages, and the purpose of performing these calculations is to determine the current circulations and the values of the residual voltages in the nodes. This paper presents the behavior of the 220/110/20 kV power substation Sardanesti to certain types of short-circuits in order to verify the stability of the system in the Oltenia area and to develop a strategy on the safety and security of the National Energy System. [ABSTRACT FROM AUTHOR]

Frequency spectral analysis and resistive tensometry are two fundamental techniques in engineering, used to monitor and evaluate the durability of structures and mechanical equipment. Spectral analysis in the context of rotary excavators is a method of evaluating the dynamic characteristics of these machines, using the decomposition of signals into their spectral components. This approach is essential for understanding the dynamic behavior of rotary excavators and identifying structural elements or machine parts that can produce resonant frequencies. For the work methodology has been considered the excavator with rotor type ERc 1400-30/7M, for which in the first stage the specific deformations were measured on certain structural elements, and in the second stage they been determined by the finite element method the first natural frequencies to be able to compare them with the dominant frequency determined from the measurement of the specific strains. [ABSTRACT FROM AUTHOR]

The paper deals with a case study for carried out in order to justify the installation of a gas cogeneration system fitted with an internal combustion engine, system used to supply electricity and heat to the users of an energy user which exceeds 1000 toe/year. 2 scenarios were therefore compared based on the energetic analysis: -the actual scenario in which energy is supplied from the National Energetic System. - the scenario in which a combined heat and power plant is used. The amount of energy saved yearly, the specific fuel consumption and the environmental impact were determined by the comparative study. The diagrams representing the variation of the performance indicators according to the operation period were also created. The usefulness of the paper consists in the creation of the yearly optimum installation operation time chart.

Copyright of EMERG: Energy. Environment. Efficiency. Resources. Globalization is the property of Romanian National Committee of World Energy Council and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)