 Subjects -> CONSERVATION (Total: 128 journals)
| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z | | The end of the list has been reached or no journals were found for your choice. |
|
|
- Compressibility behavior of conditioned sandy clay considering the
physical degradation of foam: tunneling issue
Authors: Mœz SELMI et al.
Abstract: Surfactants in the form of liquid foam are commonly used for ensuring the fluidity of conditioned soil during shield tunneling in mining zone. The compressibility can be significantly affected, depending on the percentage of fine soil. Thus, this paper investigates the compressibility of foam-conditioned fine soil. Oedometric tests as a function of the percentage of foam have been performed. Foam’s stability was analyzed, considering a laboratory soil made from 40% kaolinite and 60% of sand and mixed with a foaming agent based on an anionic surfactant. Experimental results showed that the foam stability was manifested through a reduction of the foam’s volume followed by liquid drainage, under loading and due to the foam’s physical degradation over time. The compressibility increases with the adding rate of the foam in the soil. Therefore, consolidation and foam’s degradation over time are two factors that allow the recovery of the compressibility property of conditioned soil.
PubDate: Wed, 01 Nov 2023 12:30:50 PDT
- Ventilation of tunnels during drilling using a forcing ventilation system
– a case study
Authors: Krzysztof Słota et al.
Abstract: In Poland, more and more tunnels are being built using mining methods. Mostly ventilation systems are described for tunnels already commissioned. There are few examples of ventilation calculations for tunnels under construction. The paper shows a case study where calculations were made of the minimum air volume flow required to ventilate a tunnel during its tunnelling using four duct ventilation systems. The first system used two separate fans with a 1200 mm diameter duct line, the second system changed the diameter of the duct line to 1400 mm, the third system used one fan with two 1200 mm diameter duct lines connected in parallel, and the fourth system increased the diameter of the duct line to 1400 mm. Fan power requirements were determined for these layouts. The cost statement shows that it is advantageous to change the diameter of the duct line to a larger one – reducing the total cost by about 10%. With the assumed electricity prices, the more favourable variants are the systems for which two fans with separate duct lines are provided – a cost difference of about 5%.
PubDate: Mon, 30 Oct 2023 16:17:48 PDT
- Influence of explosive maximum instantaneous charge on blasting
environmental impact
Authors: Olukemi Yetunde Odeyemi et al.
Abstract: Our research looked at the effect of explosive maximum instantaneous charge on ground vibrations and noise levels during blasting operations at the Calaba limestone quarry in Nigeria. Vibrock (V9000) seismograph was used to take readings related to ground vibrations and noise generated during all blasting operations that took place in the quarry for a period of one year. The results obtained indicate that the average ground vibration readings fall between 0.25mm/s to 3.6mm/s and the average noise decibel generated during the blasting operations between 35 to 158 dB. An artificial neural network (ANN) model is developed in this study for the prediction of blast-induced ground vibration and noise level. The proposed ANN model was compared with existing empirical models and was found to give the highest prediction accuracy. It was revealed that both noises generated and ground vibrations during all blasting operations increase with an increase in explosive maximum instantaneous charge. Additionally, the measuring equipment distance from the blast site was also revealed to have a negative correlation with noise generated and ground vibrations.
PubDate: Mon, 30 Oct 2023 16:17:41 PDT
- Effect of priming and explosive initiation location on pull in hard rock
underground mine
Authors: K.K. Rao et al.
Abstract: In the development of hard rock mines, achieving maximum pull after blasting plays a crucial role. Various machines have been developed for rock cutting, but still, due to flexibility and cost-effectiveness, drilling and blasting are preferred. To enhance the effectiveness of this method, several techniques have been developed, including the use of appropriate stemming material, double-primer placement, selecting optimal initiation locations, improving blast designs, and exploring stress superposition techniques through electronic detonators. This research paper focuses on investigating the effect of the priming and explosive initiation location on pull through an experimental approach. The study specifically examines the influence of different initiation approaches on pull, with a particular focus on inverse initiation without solid decking. The findings indicate that inverse initiation without solid decking reveals the best pull for competent rock. Additionally, the inverse initiation with 1st and 2nd square cut solid decking (double detonators with different delays) and spacers in periphery holes was found to be the best choice to eliminate the post-blast sockets with reasonable pull for weathered competent rock.
PubDate: Sat, 21 Oct 2023 07:00:01 PDT
- Open-Cast Mining Deformations Monitoring using Sentinel-1 SAR data (SBAS
technique)
Authors: Mahvash Naddaf Sangani et al.
Abstract: Land surface deformation created by mining activities can have negative impacts on the environment. Measuring them can be a tool for managing the environmental impacts of mining. Synthetic Aperture Radar Interferometry is a remote sensing method for measuring deformations. The main aim of this research is to investigate the deformation phenomenon on a region scale and extend our understanding of it to all mining deformation areas across the country. This paper used Small Baseline Subset Interferometric Synthetic Aperture Radar technology to obtain deformations information in the Sangan mine based on mining activities. We used 48 scenes of Single Look Complex(SLC) data acquired by the Sentinel-1A, C-band of the European Space Agency descending orbit paths from 2014 to 2020. The Time Series of SBAS results show that the deformation velocity rate is about –20 to –35 mm/yr, and the displacement is attributed to approximately –120 mm in the Line of Sight direction. The main deformation zone is situated in the mining area on the main alluvial fan. This study presented the relationship between deformations and mining activity's effects on the ground. Mining activities were accompanied by ground deformation in the mining area: the ground deformation is exacerbated by the increasing mining quantity, and as a result will cause erosion, flood, and other geomorphologic phenomena in the area. We compared the results of the SBAS technique with leveling data for validating the data of SBAS. Their comparison shows approximately suitable agreement with the results of SBAS.
PubDate: Sat, 30 Sep 2023 04:54:32 PDT
- Numerical modelling of Uniaxial Compressive Strength laboratory tests
Authors: Phu Minh Vuong Nguyen et al.
Abstract: In the last decades, numerical modelling has been widely used to simulate rock mass behaviour in geo-engineering issues. The only disadvantage of numerical modelling is the reliability of required input data (e.g. mechanical parameters), which is not always fully provided due to the complexity of rock mass, project budget, available test methods or human errors. On the other hand, it was proven in many cases that numerical modelling is a helpful tool for solving such complex problems, especially when coupled with the results of laboratory and in-situ tests. This paper presents an attempt to determine the proper numerical constitutive model of rock and its mechanical parameters for further simulating rock mass response based on the outcomes of laboratory testing. For this purpose, the available constitutive models, including mechanical parameters, were taken into account. The simulation performance with the selected constitutive models is demonstrated by matching the numerical modelling results with the uniaxial compressive strength laboratory tests of rock samples from the Bogdanka coal mine. All numerical simulations were carried out using the finite difference method software FLAC3D
PubDate: Sat, 30 Sep 2023 04:54:25 PDT
- Multi-criteria analysis of the possibility of retrofitting the system of
rainwater drainage from subsidence basins in a liquidated mine.
Authors: Andrzej Chmiela et al.
Abstract: Mine closure is the natural final stage of mining activity. The process of financing mine liquidation is complex and expensive. The many years of conducted hard coal extraction affect the surface height differences. Analyses of the shifts in hydrogeological conditions and water hazard states in mining plants led to legal regulation adaptations, primarily in terms of hydrogeological documentation preparation, and made it necessary to conduct work concerning new options for water hazard assessment and prevention. Current subjects of particular interest include shifts in terrain morphology and the water regime, resulting in periodic flooding and permanent flooding of the most depressed areas as well as changes in the directions and intensity of surface water flows. This publication presents a multi-criteria analysis of the possibility of reducing the liquidation costs of an inactive mine through the retrofitting of the existing system of rainwater drainage from subsidence basins. The analysis revealed the primary factors disrupting the course of the drainage process and the problems resulting from them. Technically feasible solutions is presented, together with their assessment. Applying the multi-criteria analysis made it possible to select optimal solutions from a group of proposed technical system retrofitting variants
PubDate: Tue, 26 Sep 2023 01:06:03 PDT
- Remote sensing and GIS based approach to evaluate the impact of stone
quarrying and crushing activities on land resources
Authors: R. S. Chaurasia et al.
Abstract: The land is one of the most treasures to support life, like food, fibre, medicine, and minerals, etc. Stone quarrying is one of the key elements which supports socio-economic development and industrial expansion. RS and GIS play an important role in environmental assessment to monitor the stone quarries and related activities for time to time. The present study was carried out to evaluate the impact of stone quarrying and crushing activities (SQCA) on land resources. Therefore, matrix change analysis of 2021, 2015, 2008 and 2003 were used for change detection. High-resolution Google Earth Pro images were used for the assessment of spatial as well as temporal changes caused by stone quarries and associated activities, which result in land use/land cover changes. The results show that the temporal changes in and around the quarrying sites over 18 years have contributed to dynamic changes in land use/ land cover. According to the study, damaging mining operations have grown in the area. SQCA are mostly carried out on agricultural land as well as wasteland, which decreases about 18.44% and 59.89% during the study period. Abandoned pits left without reclamation converted to derelict ponds degrading the landscape and becoming dangerous for humans and the ecosystem.
PubDate: Thu, 24 Aug 2023 11:26:06 PDT
- Predictive model of seismic vibrations’ peak value induced by
multi-face blasting
Authors: Krzysztof Fuławka et al.
Abstract: The seismicity level induced by blasting in the Polish copper mines is very important inlight of the efficiency of active rockburst prevention and safe conduct of blasting operations in the vicinity of the mining infrastructure such as shafts, workings, or function chambers (e.g., workshops, storages, etc.). Knowledge of the seismic vibrations’ peak value might be the basis for designing blasting works in a way that ensures desired seismic effect. However, current experiences show that Peak Particle Velocity prediction models developed so far do not apply to multi-face blasting, where there are many vibrations’ sources at the same time dotted across the mining panel. This paper presents the assumptions of a new empirical model with validation data gathered in the underground trials of group blasting. This new method allows for determining the vibration level generated by firing a single face and the value of amplitude amplification resulting from the increased number of faces fired simultaneously in the group. Preliminary analysis shows that this newly developed predictive model is characterized by a high level of reliability and therefore was applied to assess the effectiveness of blasting works in the selected panel in one of the mines belonging to KGHM Polska Miedź S.A.
PubDate: Tue, 22 Aug 2023 09:10:10 PDT
- Managing the rock mass destruction under the explosion
Authors: Maksym Kononenko et al.
Abstract: Using the theory of elasticity and the main provisions of the quasi-static-wave hypothesis of the mechanism of the destruction of a solid medium under the action of an explosion, analytical modelling of the parameters of the formation of crumpling zones and crushing of the rock mass around the charging cavity during its explosive loading was carried out. Analytical models of the radii of the crumpling, intensive fragmentation and fracturing zones formed around the charging cavity in the rock mass during its explosive loading, taking into account the pressure of the explosion products, the limit of tensile-compressive strength of the rocks, their structural composition, fracturing and compaction under the action of rock pressure, were developed. Based on the change in the stress-strain state of the rock mass under the action of the explosion, numerical modelling of the radii of the zones of crumpling, intensive fragmentation and fracturing was performed using the finite element method. According to the simulation results, the power dependence of the change in the radii of the crumpling and fragmentation zones of the rock mass was determined depending on the diameter of the charging cavity, the pressure of the explosion products, and the limit of rock compressive strength. By comparing the results of analytical and numerical modelling for rigid boundary conditions of a homogeneous non-cracked rock mass, the difference in the values of the radii of the defined zones was established as being 4, 8 and 6%, respectively. The resulting analytical models of the radii of crushing zones, intensive fragmentation and fracturing increase the accuracy of estimating the parameters of rock mass destruction by explosion by up to 50% and improve the parameters of drilling and blasting operations when carrying out mining operations, special purpose cavities and rocking of the rock mass.
PubDate: Sun, 13 Aug 2023 13:09:19 PDT
- Application Geological Strength Index (GSI) quantification method on the
characterization of carbonate rock mass
Authors: Singgih Saptono et al.
Abstract: Determining GSI as a representation of the presence of rock mass in slope analysis continues to develop. The development of the quantitative GSI method was carried out because the basic (qualitative) GSI values were deemed too subjective so the results from the use of the quantitative GSIwere expected to be more objective and accurate. The method used is to combine 3 GSI quantitative methods to find GSI based on surface conditions and joint structure. The results showed that the Quantitative GSI value was smaller than the GSI predictive value (qualitative). The GSI approach with RQD and UCS parameters is also presented to describe rock mass conditions due to changes in GSI values, and the third result shows a directly proportional relationship, the greater the GSI value, the greater the RQD and UCS values. The combined application of these three quantification methods is suitable for slopes that have not been properly exposed so that surface and structural conditions can only be seen from visual observations of outcrops and some initial construction slopes.
PubDate: Mon, 07 Aug 2023 03:34:58 PDT
- Nickel recovery from low-grade laterites: study of thermal pre-treatments
to improve the efficiency of the hydrometallurgical process
Authors: Johana Borda et al.
Abstract: The processing of lower-grade laterites to obtain nickel has increased due to the gradual depletion of higher-grade sulphide ore reserves. However, the extraction from laterites has been limited because conventional technologies imply a considerable expense of energy or reagents. In this document, the effect of thermal pre-treatments on a laterite sample is demonstrated to improve nickel leaching under moderate conditions. The influence of agents such as coke, coal and NaCl in the heat treatment was also studied. With the results it is presumed that part of the nickel occluded in the goethite migrates to the iron oxides surface during the heat treatment; this is why the dissolution of nickel is linked to that of iron. The highest extractions (64.7% nickel) were achieved by combining heat treatment and leaching with 1M H2SO4 at ambient conditions. Compared to direct leaching of unpretreated laterite, leaching rates for this metal are increased by 26.5%. The chlorinating calcination and the optimization of the studied variables will be favourable to reach higher metallic extractions.
PubDate: Sun, 30 Jul 2023 22:19:43 PDT
- European feedback on post-mining seismicity
Authors: Isabelle Contrucci et al.
Abstract: Following the Paris Agreement adopted in 2015, Europe has committed to reducing its greenhouse gas emissions. In this context, the abandonment of coal as an energy source, both in terms of consumption and production, will lead to the closure of many mines in the years to come.Mine closure guidelines to manage residual mining risks already exist in European countries. However, they do not include post-mining seismic risk management due to a lack of sufficient studies and knowledge on this subject. After mining closure, the flooding of the mining works leads to hydromechanical loading of the underground and, in the longer term, to diffusion and an increase in the pore pressure. These conditions can lead, in certain situations, to the reactivation of tectonic faults, which may cause seismic events strong enough to be felt on the surface or even produce damage. Events of lower magnitudes, usually attributed to the remobilization of old mining works, are referred to as post-mining seismic hazards.The European RFCS PostMinQuake project, which started in 2020, aims to study this hazard at five mining basins located in France, Germany, Poland and the Czech Republic, known to have experienced significant seismicity during their operation. This analysis, based on the feedback of the partners of the project, aims to frame an inventory of the five studied mining basins, which all encounter post-mining seismicity problem today. Three basins out of five show events with local magnitudes of the order of 3 to 3.5, which took place between nine and thirteen years after the closure of the mines. Even though the magnitudes of these earthquakes are small to moderate, they are felt on the surface as they occur at shallow depths.In all of the considered countries, a national seismological network exists, however, none of them is fully dedicated to post-mining seismic monitoring. These networks generally consist of a sparse mesh of stations, which does not allow the detection of events of magnitude less than 1 and the location of events have high spatial uncertainties. France is not an exception, but it relies on microseismic monitoring to detect early signs of instability at the level of mining structures and to anticipate the possible appearance of surface disorders. Out of the five basins that are studied, the Gardanne basin, which has been monitored since 2008, is the most documented case study of post-mining seismicity. This article also shows the difficulty in identifying the key conditions and factors that can lead to the remobilization of faults.
PubDate: Sun, 30 Jul 2023 22:19:35 PDT
- Influence of cutting parameters on the performance of plough during hard
rock cutting in coal mining
Authors: Sathish Kumar Palaniappan et al.
Abstract: Coal ploughs have proved very successful on many faces in various parts of the world. Recently, there has been a general tendency in longwall working to increase the speed at which the machine progresses along the coal face. An increase in production rate demands enhances either due to depth of penetration or cutting speed. This, in turn, results in increasing power demand and also the force acting on an individual pick. To get maximum efficiency from a cutting machine, a number of parameters need to be investigated. The first and foremost thing of interest is naturally the pick geometry. The cutting force can be expected to depend mainly on the rack angle and clearance angle of the tool. The second parameter is the cutting depth, which when enhanced, increases the rate of advancement and, at the same time, results in enhanced cutting force. This results in large power demand and increases wear of picks. Thirdly, cutting speed, in which higher cutting speed will increase the production rate but at the same time is expected to enhance the power demand and the cutting force. This paper aims at investigating the cutting efficiency of the plough by simulating the coal cutting operation in the laboratory. The effect of three main parameters like pick geometry, cutting depth, and cutting speed, on cutting efficiency have been studied in detail. The cutting force elevates at a faster rate with an increase in depth at higher speeds. The percentage increase in force is nearly 20% for a speed increase of 20%.
PubDate: Mon, 17 Jul 2023 12:00:45 PDT
- Geophysical imprint of mining-induced rock mass deformation in the area of
construction disaster in Bytom (Poland)
Authors: Andrzej Kotyrba et al.
Abstract: The paper presents the analysis of the results of geophysical surveys conducted in the mining area located in Bytom – Karb (USCB, Poland) in the aspect of identifying the causes of significant damage to the complex of inhabited tenement houses which occurred in 2011. The surveys were carried out by microgravimetric and GPR methods. The construction disaster was caused by the exploitation of one of the hard coal seams at a depth of about 800 m along the mining longwall running underneath the settlement. The terrain deformation parameters exceeded the forecasted values, and in several places discontinuities took linear forms along the diagonal directions to the front lines of the longwall. In addition to the sliding movement, the rotational movement appeared in the ground. As a consequence of spatially complex ground movements, some buildings suffered significant damage. The extent of the damage turned out to be catastrophic and immediate relocation of the inhabitants and demolition of the buildings became necessary. The article is an attempt to explain the nature and the causes of excessive terrain deformations in relation to those modeled on the basis of analysis and interpretation of geophysical data from the current measurements as well as archival maps and geological and mining cartography data.
PubDate: Fri, 14 Jul 2023 09:25:05 PDT
- Status and prospects of fully mechanized mining technology in Vietnam coal
mines from 2005 to 2020
Authors: Hai Duong Duc et al.
Abstract: This paper analyzes the achievement and the failures of applying the mechanized mining method in underground coal mines by the Vietnam National Coal – Mineral Industries Holding Corporation Ltd. (VINACOMIN) for 15 years (from 2005 to 2020). It also proposes the recommendations for developing mechanized mining in order to improve coal production, productivity and safety management for the sustainable development of Vietnam’s underground coal mining in the period 2021-2025
PubDate: Thu, 29 Jun 2023 04:59:09 PDT
- Evaluating the impacts of the transition from open-pit to underground
mining on sustainable development indexes
Authors: Naser Badakhshan et al.
Abstract: Sustainable development is about creating a balance between development and environment, and it consists of three essential principles: environment, society, and economy. Today, one of the most important challenges in deep open pit mines is the transition from open pit to underground, which has positive and negative impacts on sustainable development indexes. In order to reduce these adverse impacts, the impact of various parts of the transition operation on these indexes should be evaluated and corrective and preventive measures should be implemented. In this study, using a hybrid semi-quantitative approach, the effects of the transition in the Songun copper mine were evaluated. The obtained results showed that the transition in Songun copper mine has the greatest impact on the economic index of sustainable development with a value of 67.72 percent. In addition, the amount of impact of transition in this mine on environmental and social index is 41.74 and 39.84% respectively. In the meantime, the most significant impact was determined on components such as production rate and productivity, mine life, operation and capital cost, mineral value and income per ton of ore, mine closure (and reclamation) cost, Initial investment rate of returns, post–mining land use type.
PubDate: Wed, 28 Jun 2023 09:05:00 PDT
- Applications of UAVs in mine industry: A scoping review
Authors: Dang Tuyet Minh et al.
Abstract: In recent years, a variety of technologies have improved mining operations. One of them is the Unmanned Aerial Vehicles (UAVs), the emerging technology that has been changing the mining process, boosting mining safety and productivity. The main purpose of this paper is to review the applications of UAVs in the mining industry based on the results of 113 research papers over the past twelve years, from 2010 to May 2022. The potential applications of UAVs in the mining industry are broad. Based on the paper identified, eight categories are used to classify UAV applications in the mining sector. The reviewed literature revealed that UAVs are an excellent tool for multitasking at any stage of a mining project and in any type of mine. The findings of this study may serve as some guidelines for developing the necessary requirements for the use of UAV technology in mine sites.
PubDate: Tue, 27 Jun 2023 04:29:11 PDT
- Research on stability of rock mass and +30 level surface construction
works when re-exploiting the seam H10 at Mong Duong Coal Mine, Vietnam
Authors: Tien Trung Vu et al.
Abstract: The re-exploitation of coal seams located near the ground is one of the solutions to increase output, reduce mining investment costs, and avoid wasting coal resources. The re-exploitation of coal seams will also cause instability of the surrounding rock mass and may affect surface construction works. Through the process of re-exploiting the longwall in seam H10 at Mong Duong Coal Mine, the authors have studied and evaluated the stability of the rock mass and +30 level surface works (including fan station and gateroad). To achieve the results in this study, the numerical simulation model method and the analytical method were applied. The model analysis results have determined that the displacement and deformation areas of the rock mass around the mining area correspond to the length of the cut in the strike direction of the longwall H10. The analysis and calculation results from the model show that the longwall in seam H10 can be re-exploited when leaving a protective coal pillar about 50 m from the center of the +30 fan station at the east side; this distance ensures the stability of the rock mass that located near the ground and the surface works at +30.
PubDate: Thu, 22 Jun 2023 23:49:37 PDT
- Evaluating the post-mining land uses of former mine sites for sustainable
purposes in South Africa
Authors: Sphiwe E Mhlongo
Abstract: This paper uses a case study of an abandoned magnesite mine in the Limpopo Province of South Africa to find ways of identifying post-mining land used from the current uses of the abandoned mine sites or features. The approach used involved carrying out a field characterization of the mine site and documentation of the current uses of the features of the abandoned mine site. The technique used to identify the internal and external factors of the land uses involved analyzing their Strength, Weakness, Opportunities, and Threats. The Analytic Hierarchy Process (AHP) technique was used for further ranking of the land uses to identify the most post-mining or rehabilitation land uses for the different parts of the mine. Lastly, the earthwork requirement in reshaping the terrain of the mine to support the selected land uses was estimated from the 3D-terrain models generated from height data collected using a Real-Time Kinematic Geographical Positioning System. The results of the study identified land use that needs further surface development as the most appropriate for the abandoned Nyala Mine. These land uses demonstrated the potential of addressing the hazards of the mine with the clear promise of improving the socio-economic status of the host communities.
PubDate: Thu, 22 Jun 2023 03:15:58 PDT
|
Open Access journal
