Case Study
N. Aziz; A. Mirzaghorbanali
Abstract
Canister desorption is a widely used technique to measure the gas content of coal. The gas content data, when normalized to volume/weight and multiplied by coal seam mass, is used to estimate the gas in place in an area around the cored hole. However, the gas content and the percentage of each constituent ...
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Canister desorption is a widely used technique to measure the gas content of coal. The gas content data, when normalized to volume/weight and multiplied by coal seam mass, is used to estimate the gas in place in an area around the cored hole. However, the gas content and the percentage of each constituent are likely to be influenced by trapped air in the canister at the time of the coal enclosure and subsequent sealing. Freshly-cored coal samples were collected from three mines, mining coal from Bulli seam, Sydney Basin. The studied underground mines were Appin West, West Cliff, and Tahmoor. The research programme, spanning for a period of four years, focused only on the influence of the trapped air in the canister on the coal gas percentage of each constituent. It was found that the percentage of each coal gas constituent was influenced by the trapped air in the canister space. The effect of trapped air was extended to the component percentage of the gases in the crushed coal samples, normally used for the estimation of Q3.
Case Study
J. Mantey; F. Owusu-Nimo; K.B. Nyarko; A. Aubynn
Abstract
The uncontrolled spread of illegal artisanal small-scale gold mining (ASM), popularly termed “galamsey” in Ghana, has, for decades, impacted adversely upon water bodies, soils, wildlife, human health, and safety. A lack of understanding, however, of the types of galamsey, their operational ...
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The uncontrolled spread of illegal artisanal small-scale gold mining (ASM), popularly termed “galamsey” in Ghana, has, for decades, impacted adversely upon water bodies, soils, wildlife, human health, and safety. A lack of understanding, however, of the types of galamsey, their operational attributes, and their relative impacts has unfortunately hindered an effective policy response despite numerous calls from civic societal groups to address this menace. This paper is part of a comprehensive study in 11 selected municipal and district assemblies of the Western Region of Ghana to help provide an in-depth understanding into the galamsey operations in Ghana. It discusses the various forms of galamsey, their operational attributes, and relative environmental impacts. Through extensive literature review, site visits, and task observations, five broad categories and 11 sub-groupings of galamsey were unearthed based on the gold deposit type, resources used, origin of technology used, mining, and processing style as well as the local names given. These include (1) Placer/alluvial galamsey (“dig and wash”, “washing plant”, “washing board”, “anwona”, dredging, and panning), (2) Underground galamsey (abandoned underground shafts and “sample pit”), (3) Surface (“chamfi”) galamsey, (4) Mill-House galamsey, and (5) Selection galamsey. Whilst the underground and selection galamsey involve ore mining only, the mill-house focuses exclusively on ore processing. The alluvial and surface galamsey, however, involve simultaneous mining and ore processing activities. The information presented in this paper could prove valuable to policy formulation efforts, design, and implementation of effective wasteland remediation programs by governments, conservation organizations, and other stakeholders in hard-hit regions with similar illegal gold mining dilemma.
Case Study
Z. Bayatzadeh Fard; F. Ghadimi; H. Fattahi
Abstract
Determining the distribution of heavy metals in groundwater is important in developing appropriate management strategies at mine sites. In this paper, the application of artificial intelligence (AI) methods to data analysis,namely artificial neural network (ANN), hybrid ANN with biogeography-based optimization ...
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Determining the distribution of heavy metals in groundwater is important in developing appropriate management strategies at mine sites. In this paper, the application of artificial intelligence (AI) methods to data analysis,namely artificial neural network (ANN), hybrid ANN with biogeography-based optimization (ANN-BBO), and multi-output adaptive neural fuzzy inference system (MANFIS) to estimate the distribution of heavy metals in groundwater of Lakan lead-zinc mine is demonstrated.For this purpose, the contamination groundwater resources were determined using the existing groundwater quality monitoring data, and several models were trained and tested using the collected data to determine the optimum model that used three inputs and four outputs. A comparison between the predicted and measured data indicated that the MANFIS model had the mostpotential to estimate the distribution of heavy metals in groundwater with a high degree of accuracy and robustness.
Case Study
H. Dehghani; A. Siami; P. Haghi
Abstract
One of the most important steps involved in mining operations is to select an appropriate extraction method for mine resources. After choosing the extraction method, it is usually impossible to replace it with another one because it may be so expensive that implementation of the entire project could ...
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One of the most important steps involved in mining operations is to select an appropriate extraction method for mine resources. After choosing the extraction method, it is usually impossible to replace it with another one because it may be so expensive that implementation of the entire project could be economically impossible. Choosing a mining method depends on the geological and geometrical characteristics of the mine. Due to the complexity of the process of choosing an appropriate mining method and the effect of the parameters involved on the results of this process, it is necessary to utilize the new decision-making methods that have the ability to consider the relationship between the existing parameters and the mining methods. Grey and TODIM (an acronym in Portuguese, i.e. Tomada de Decisão Interativa Multicritério) decision-making methods are among the existing ones, which in addition to the convenience, show high accuracy. The proposed models are presented to determine the best mining method in the Gol-e-gohar iron ore mine in Iran. The results obtained are compared with the methods used in the previous research works. Among the decision-making methods introduced, the open pit mining method is the most appropriate option and the square-set mining is the worst one.
Case Study
M. Mohebbi; A.R. Yarahmadi Bafghi; M. Fatehi Marji; J. Gholamnejad
Abstract
Presence of joints and fractures in rocks strongly influences the behavior of the rock mass by dividing the media into smaller units. These structures intensify the potential instability besides the development of sliding and rotational movements. The assumption of discontinuum media changes the whole ...
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Presence of joints and fractures in rocks strongly influences the behavior of the rock mass by dividing the media into smaller units. These structures intensify the potential instability besides the development of sliding and rotational movements. The assumption of discontinuum media changes the whole analysis conditions in relation to the continuum analysis. Acquisition of geometrical and structural discontinuity data alongside their mechanical properties is of paramount importance in a rock mass analysis. Orientation, spacing, expansion, and other geometrical characteristics of the rock mass and their relative geometrical position to the studied projects influence the pattern and potential of failure. Therefore, inevitably, the first step involved in the analysis of rock mass is geometric data collection of the discontinuities as a crucial step before analysis. In this study, the traditional data collection methods in structural discontinuities with their disadvantages are reviewed. Then the discontinuity data collection based on digital image analysis is developed and applied in a case study to several walls of the Choghart iron ore mine. The results obtained show that this method has a very good accuracy in assessing the fine structures, and also it collects data in a much shorter time. This study, therefore, suggests that the proposed method can be used as a practical approach.
Case Study
M. Rezaee Rad; Sh. Shahhoseini; M. Janfada; H. A. Mirzaee; P. Kelidari
Abstract
Low grade diasporic bauxite in the Jajarm mine with an A/S (Al2O3/SiO2) ratio of 2.3 is not usable in the Bayer process at Jajarm Alumina Complex. Due to the severe interlocking effect between the diaspore and aluminosilicate minerals (Chamosite and Kaolinite) and iron-containing minerals in a microcrystal ...
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Low grade diasporic bauxite in the Jajarm mine with an A/S (Al2O3/SiO2) ratio of 2.3 is not usable in the Bayer process at Jajarm Alumina Complex. Due to the severe interlocking effect between the diaspore and aluminosilicate minerals (Chamosite and Kaolinite) and iron-containing minerals in a microcrystal matrix, the thermo-chemical treatment, which is independent from micro-mineralogy, was chosen for bauxite desilication. Five parameters affecting the process and their interactions were investigated using the Taguchi experimental design method. The results obtained showed that there was an interaction between the furnace temperature and the leaching time. Moreover, the optimum values for the parameters involved in the thermo-chemical treatment were determined to be a furnace temperature of 950 °C, a furnace residence time of 90 min, a leaching agent (soda) concentration of 150 g L-1, and a leaching time of 120 min, where the solid content (in leaching) had no effect. Moreover, a model was proposed using the Dx7 software to predict the A/S ratio. The ratio was predicted to be 7.52 at the optimum conditions, whereas in the experiments carried out under the same conditions, it was obtained to be 6.96 ± 0.2, which means a 59% decrease in silica and an increase in the A/S ratio of up to 3 times with 80% weight recovery.
Case Study
H. R. Nejati; Seyed A. Moosavi
Abstract
Assessment of the correlation between rock brittleness and rock fracture toughness has been the subject of extensive research works in the recent years. Unfortunately, the brittleness measurement methods have not yet been standardized, and rock fracture toughness cannot be estimated satisfactorily by ...
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Assessment of the correlation between rock brittleness and rock fracture toughness has been the subject of extensive research works in the recent years. Unfortunately, the brittleness measurement methods have not yet been standardized, and rock fracture toughness cannot be estimated satisfactorily by the proposed indices. In the present study, statistical analyses are performed on some data collected from the literature to develop two equations for estimation of modes I and II fracture toughness. Then a probabilistic sensitivity analysis is performed to determine the impact of the input parameters on the output ones. Based on the results obtained for the probabilistic analysis, a new empirical brittleness index including tensile strength, uniaxial compressive strength, and elastic modulus is suggested for estimating modes I and II fracture toughness. The analyses results reveal that the proposed index is capable of estimating rock fracture toughness with more satisfactory correlation compared to the previous indices.
Case Study
A. Khojamli; F. Doulati Ardejani; A. Moradzadeh; A. Nejati Kalateh; A. Roshandel Kahoo; S. Porkhial
Abstract
The Ardabil geothermal area is located in the northwest of Iran, which hosts several hot springs. It is situated mostly around the Sabalan Mountain. The Sabalan geothermal area is now under investigation for the geothermal electric power generation. It is characterized by its high thermal gradient and ...
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The Ardabil geothermal area is located in the northwest of Iran, which hosts several hot springs. It is situated mostly around the Sabalan Mountain. The Sabalan geothermal area is now under investigation for the geothermal electric power generation. It is characterized by its high thermal gradient and high heat flow. In this study, our aim is to determine the fractal parameter and top and bottom depths of the magnetic sources. A modified spectral analysis technique named “de-fractal spectral depth method” is developed and used to estimate the top and bottom depths of the magnetized layer. A mathematical relationship is used between the observed power spectrum (due to fractal magnetization) and an equivalent random magnetization power spectrum. The de-fractal approach removes the effect of fractal magnetization from the observed power spectrum, and estimates the parameters of the depth to top and depth to bottom of the magnetized layer using the iterative forward modelling of the power spectrum. This approach is applied to the aeromagnetic data of the Ardebil province. The results obtained indicated variable magnetic bottom depths ranging from 10.4 km in the northwest of Sabalan to about 21.1 km in the north of the studied area. In addition, the fractal parameter was found to vary from 3.7 to 4.5 within the studied area.
Short Communication
S. Moghaddam; S. Dezhpasand; A. Kamkar Rohani; S. Parnow; M. Ebrahimi
Abstract
Protection of water resources from contamination and detection of the contaminants and their treatments are among the essential issues in the management of water resources. In this work, the time-lapse electrical resistivity tomography (ERT) surveys were conducted along 7 longitudinal lines in the downstream ...
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Protection of water resources from contamination and detection of the contaminants and their treatments are among the essential issues in the management of water resources. In this work, the time-lapse electrical resistivity tomography (ERT) surveys were conducted along 7 longitudinal lines in the downstream of the Latian dam in Jajrood (Iran), in order to detect the contamination resulting from the direct injection of a saltwater solution in to the saturated zone in the area. To investigate the pollutant quantities affecting the resistivity of this zone, the temperature and electrical conductivity measurement were carried out using a self-recording device during 20 days (before and after the injection). The results obtained from the self-recording device measurements and ERT surveys indicated that in addition to the salt concentration changes in water, the resistivity changes in the saturated zone were dependent on other factors such as the lithology and absorption of contaminants by the subsurface layers. Furthermore, the expansion of contamination toward the geological trend, sedimentation, and groundwater flow direction of the area were shown.
Case Study
M. Nikkhah; Seyed S. Mousavi; Sh. Zare; O. Khademhosseini
Abstract
The joints between segmental rings can withstand a certain amount of bending moment as well as axial and shear forces. Generally, in the structural analysis of tunnel segmental lining, the joints can be modeled as elastic hinges or rotational springs, and their rigidity should be demonstrated in terms ...
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The joints between segmental rings can withstand a certain amount of bending moment as well as axial and shear forces. Generally, in the structural analysis of tunnel segmental lining, the joints can be modeled as elastic hinges or rotational springs, and their rigidity should be demonstrated in terms of the rigidity of the joints or their rotational stiffness. Therefore, the bending moment acting on the tunnel lining is reduced. Hence, the tunnel designers are free to choose a lining with a lower cost. In this research work, especially considering the joints, the structural analysis of the segmental lining with variation in the flexural stiffness of the joints ( ), soil resistance coefficient ( ), number of segmental lining joints, and joint arrangement of segmental lining were carried out by the Force-Method equations. The imposed bending moment and axial forces were computed based on the Beam-Spring method, which is widely used to analyze the internal forces of segmental lining, and compared them with the results of the Force-Method equations. Then the effects of joint arrangement patterns and joint rotational spring stiffness on the results of the Beam-Spring analysis were evaluated. Finally, the optimum characteristics of the reinforced concrete segmental lining design were evaluated using the interaction diagram of bending moments and axial forces. The results obtained showed that the presented pattern for the segmental lining at the Chamshir tunnel was imposed against the external pressures on the segmental lining with an acceptable safety factor.
