Mineral Processing
M. Naderi; Seyed Z. Shafaie; M. Karamoozian; Sh. Gharanjik
Abstract
In this work, the parameters affecting the recovery of copper from the low-grade sulfide minerals of Sarcheshmeh Copper Mine were studied. A low-grade sulfide ore was used with a copper grade of 0.25%, which was about 28% of the mineral oxide, and the sulfide minerals made up the rest. Much more sulfide ...
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In this work, the parameters affecting the recovery of copper from the low-grade sulfide minerals of Sarcheshmeh Copper Mine were studied. A low-grade sulfide ore was used with a copper grade of 0.25%, which was about 28% of the mineral oxide, and the sulfide minerals made up the rest. Much more sulfide minerals were found to be pyrite and most of the gangue minerals were quartz, anorthite, biotite, and muscovite. In order to investigate, simultaneously, the solids (10 to 20%) and acidity (1.5 to 2.5) and shaking (110 to 150 rpm), the separation of bacteria from Sarcheshmeh Copper Mine was carried out. After adjustment of the sample, bio-leaching tests were performed in accordance with the pattern defined by the software DX7 in shaking flasks, and the Cu recovery was modeled and optimized using the response surface methodology. The influential parameters were comprehensively studied. The central composite design methodology was used as the design matrix to predict the optimal level of these parameters. Then the model equation was optimized. The results obtained showed that increasing solids (from 10 to 20%) was bad for bacteria. The highest copper recovery was equivalent to 69.91%, obtained after 21 days at 35 degrees using the Acidi Thiobacillus Ferrooxidans bacteria and a K9 medium with a pulp density of 10% and pH 1.5.
K.M. Tanguturi; R.S. Balusu
Abstract
It is necessary to obtain a fundamental understanding of the goaf gas flow patterns in longwall mine in order to develop optimum goaf gas drainage and spontaneous combustion (sponcom) management strategies. The best ventilation layout for a longwall underground mine should assist in goaf gas drainage ...
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It is necessary to obtain a fundamental understanding of the goaf gas flow patterns in longwall mine in order to develop optimum goaf gas drainage and spontaneous combustion (sponcom) management strategies. The best ventilation layout for a longwall underground mine should assist in goaf gas drainage and further reduce the risk of sponcom in the goaf. Further, in the longwall panel, regulators are installed in the maingate (MG) seals to control the gas migration on the MG side and the mine operators frequently encountered with seals leakage problems leading to abnormal gas contents in the tube bundles. Extensive parametric studies were carried out to investigate the effects of ventilation layouts, regulators, and seals leakages on the goaf gas distribution using the Computational Fluid Dynamics (CFD) techniques. The results of various CFD simulations are presented and discussed in detail in this paper.
Rock Mechanics
M. Akhyani; R. Mikaeil; F. Sereshki; M. Taji
Abstract
Predicting the wear performance of circular diamond saw in the process of sawing hard dimensional stone is an important step in reducing production costs in the stone sawing industry. In the present research work, the effective parameters on circular diamond saw wear are defined, and then the weight ...
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Predicting the wear performance of circular diamond saw in the process of sawing hard dimensional stone is an important step in reducing production costs in the stone sawing industry. In the present research work, the effective parameters on circular diamond saw wear are defined, and then the weight of each parameter is determined through adopting a fuzzy rock engineering system (Fuzzy RES) based on defining an accurate Gaussian pattern in fuzzy logic with analogous weighting. After this step, genetic algorithm (GA) is used to determine the levels of the four major variables and the amounts of the saw wear (output parameter) in the classification operation based on the fixed, dissimilar, and logarithmic spanning methods. Finally, a mathematical relationship is suggested for evaluation of the accuracy of the proposed models. The main contribution of our method is the novelty of combination of these methods in fuzzy RES. Before this work, all Fuzzy RESs only use simple membership functions and uniform spanning. Using GA for spanning and normal distribution as membership function based upon our latest work is the first work in fuzzy RES. To verify the selected proposed model, rock mechanics tests are conducted on nine hard stone samples, and the diamond saw wear is measured and compared with the proposed model. According to the results obtained, the proposed model exhibits acceptable capabilities in predicting the circular diamond saw wear.
J. Manyepa; V. Patson Mutambo
Abstract
Designing suitable extraction methods for mining randomly occurring pocket formation of gemstones has never been easy at the Musakashi emerald mine due to the limited geological information. In order to improve the productivity as well as the recovery, in this work, we undertake a detailed ...
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Designing suitable extraction methods for mining randomly occurring pocket formation of gemstones has never been easy at the Musakashi emerald mine due to the limited geological information. In order to improve the productivity as well as the recovery, in this work, we undertake a detailed geological survey (airborne, surface mapping, geochemical sampling, and trenching activities), and review, analyze, and establish the appropriate extraction methods, and conduct the economic viability of the mining emeralds in the Musakashi area. A total of 51 holes are drilled in order to define the mineralization and estimate the mineral resource for the rubble ore and the in-situ ore zones using the Surpac Geovia software. The diamond drilling unravels the existence of an alteration zone enveloping the shales in an area of 150m by 100m. The emerald is localized within these reaction zones, and is estimated to extend to a depth of about 20–30m below the surface. The total mineral resource stands at 345, 290 grams for the rubble ore and 123,870 grams for the discordant veins. From the geological information obtained, a trial pit design is established with a target of increasing recovery of emeralds from the current 10 kg to 100 kg per year.
Blessing Olamide Taiwo
Abstract
Assessment of blast results is a significant approach for the improvement of mining operations. The different procedures for investigating rock fragmentation have their limitations, causing different variation prediction errors. Thus every technique is site-explicit, and applicable for a few explicit ...
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Assessment of blast results is a significant approach for the improvement of mining operations. The different procedures for investigating rock fragmentation have their limitations, causing different variation prediction errors. Thus every technique is site-explicit, and applicable for a few explicit purposes. This work evaluates the existing empirical blast fragmentation model predictions in the case study of small-scale dolomite quarries. An attempt is made to compare the prediction accuracy of the modified Kuz-Ram model, Lawal 2021 model, and Kuznetsov-Cunningham-Ouchterlony (KCO) model with the WipFrag© analysis result and proposed artificial neural network (ANN) models. The prediction error analysis of the current models and that of the new proposed ANN models is evaluated using the three model assessment indices. The assessment indices uncover that the KCO model when compared to the modified Kuz-Ram model has the least error for most blast round percentage passing size predicted. However, the proposed artificial neural network models show high prediction exactness in predicting blast fragment mean size than the existing empirical models. Therefore, the proposed ANN models can be used to improve the productivity of small-scale dolomite blasting operation results for practical purposes.
S. Mulenga; R. Kaunda
Abstract
In this work, a new drilling and blasting design methodology is introduced and applied at a case study mine to improve productivity. For the case study copper mine, a blast diameter of 203 mm is proposed to be used in the ore zone to meet the new required production rate of 90mtpa from 75mtpa. Currently, ...
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In this work, a new drilling and blasting design methodology is introduced and applied at a case study mine to improve productivity. For the case study copper mine, a blast diameter of 203 mm is proposed to be used in the ore zone to meet the new required production rate of 90mtpa from 75mtpa. Currently, the Konya and Walter’s model is used to generate drilling and blasting design at a blasthole diameter of 172 mm. The new drilling and blast design approach is advantageous in the sense that it generates a lower specific drilling value and predicts an average fragment size compared with the current method being used. In this regard, a modified available energy blast design method that incorporates the blastability index of ore zone in the calculation of the input powder factor is introduced. The results of the blast design simulations at a 203 mm blasthole diameter shows that the modified available energy model generates a drilling and blasting design with a specific drilling value that is 15.3% less than that generated by the Ash’s and Konya and Walter’s models. Further, the modified available energy model generates a blast design with a predicted average fragment size that is 3.4% smaller than that generated by the Ash’s model, and 6.7% smaller than that generated by the Konya and Walter’s model.
Rahul Shakya; Manendra Singh
Abstract
Due to fast urbanization, there is a shortage of above-ground surfaces. Thus to reduce this shortage of above-ground surface, underground tunnels are constructed beneath the structure for transportation purposes. As a result, it is critical to understand how earthquakes affect underground tunnels, so ...
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Due to fast urbanization, there is a shortage of above-ground surfaces. Thus to reduce this shortage of above-ground surface, underground tunnels are constructed beneath the structure for transportation purposes. As a result, it is critical to understand how earthquakes affect underground tunnels, so that people's lives can be saved and service levels can be maintained. Underground constructions cannot be considered entirely immune to the impacts of ground shaking, as evidenced by the Kobe earthquake (1995), the Chi-Chi earthquake (1999), and the Niigata earthquake (2004), when some underground structures were severely damaged. A typical section at Chandani Chowk of DMRC (Delhi Metro Rail Corporation) tunnels, New Delhi, India, has been analyzed by using the finite element method. Response of the soil tunnel system for the Uttarkashi earthquake (1991) has been found out in the form of maximum forces induced in the RC liner of the tunnel, displacement, induced acceleration and stresses. The results have been compared with the available closed-form solutions. Parametric studies by considering different parameters such as effect of contraction (volume loss), influence of boundary conditions and damping, effect of interface condition between soil and tunnel, effect of displacement time history and effect of a nearby building have also been conducted. Forces in RC liners and stress concentration obtained in the present study are well-matched to those obtained by available closed formed solutions. The vertical stress concentration and volume loss depend upon the soil medium's constitutive behavior. The section under consideration was safe against the 1991 Uttarkashi earthquake. It can also be observed that, due to the presence of the building, the axial force and bending moment increased in tunnel’s liner, and the value of all three forces reduced as the position of the building was away from the tunnel. Shear force and bending moment were maximum for full slip condition between soil and tunnel lining however the effect of the interface condition on the displacement was negligible after a certain value of the interface condition.
Mineral Processing
G.G. Berhe; A. Velázquez del Rosario; Y. Abubeker; W. Girma; T. Bogale; C. Mulugeta Sisay
Abstract
The decomposition of the Ethiopian Kenticha tantalite ore was studied using the KOH fusion and H2O leaching system at 400 0C for a 1 h reaction time. The experimental results obtained showed that 27 wt% of Ta2O5 was mainly transformed into insoluble KTaO3, not to be KNbO3, and as well, into the dissolved ...
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The decomposition of the Ethiopian Kenticha tantalite ore was studied using the KOH fusion and H2O leaching system at 400 0C for a 1 h reaction time. The experimental results obtained showed that 27 wt% of Ta2O5 was mainly transformed into insoluble KTaO3, not to be KNbO3, and as well, into the dissolved liquor containing 94.73 vol% of Nb2O5 and 75.80 vol% of Ta2O5. The observations, supported by the EDXRF, XRD, and ICP-OES techniques, showed that the ratio of the dissolved mixture of Nb and Ta metal ions was beneficial to the solvent extraction from both Ta2O5 and Nb2O5. Niobium and tantalum were extracted from their neutralized alkaline dissolved and hydrolyzed solution by a new process using the EMIC/AlCl3 ionic liquid as the extractant using selective stripping, precipitation, and calcination of a highly crystalline pure 99.84 wt% of Nb2O5 and amophours 90.81 wt% of Ta2O5. The compositions of the dissolved metal ions and solids were analyzed by the ICP-OES, EDXRF, XRD, and FT-IR techniques.
Exploration
Prince Ofori Amponsah; Eric Dominic Forson
Abstract
This study was set out to delineate prospective zones of gold mineralization occurrence over the Julie tenement of Northwestern Ghana using two spatial statistical techniques, namely information value (IV) and weight of evidence (WofE) models. First, 110 locations, where gold (Au) mineralization has ...
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This study was set out to delineate prospective zones of gold mineralization occurrence over the Julie tenement of Northwestern Ghana using two spatial statistical techniques, namely information value (IV) and weight of evidence (WofE) models. First, 110 locations, where gold (Au) mineralization has been observed, were identified by field survey results derived from highly anomalous geo-chemical assay datasets. Of these 110 locations, 77 (representing 70% of the known locations, where gold has been observed) were randomly selected for training the aforementioned models, and the remaining 33 (analogous to 30% of the known Au occurrence) were used for validation. Secondly, eleven mineral conditioning factors (evidential layers) comprising analytic signal, reduction-to-equator (RTE), lineament density (LD), porphyry density, potassium concentration, thorium concentration, uranium concentration, potassium-thorium ratio, uranium-thorium ratio, geology, and arsenic concentration layers were sourced from geo-physical, geological, and geo-chemical datasets. Subsequently, by synthesizing these eleven evidential layers using the two spatial statistical techniques, two mineral prospectivity models were created in a geographic information system (GIS) environment. Finally, the mineral prospectivity models produced were validated using the area under the receiver operating characteristics curve (AUC). The results obtained showed that the IV model produced had a higher prediction accuracy in comparison with the mineral predictive model produced by the WofE with their AUC scores being 0.751 and 0.743, respectively.
Exploration
V. Adjiski; D. Mirakovski; Z. Despodov; S. Mijalkovski
Abstract
Auxiliary ventilation of the blind development heading in underground mines is one of the most challenging work activities amongst mining underground operations. The auxiliary forcing ventilation system provides positive pressure, cooling, controlling gas layering, and removing diesel fumes and dust ...
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Auxiliary ventilation of the blind development heading in underground mines is one of the most challenging work activities amongst mining underground operations. The auxiliary forcing ventilation system provides positive pressure, cooling, controlling gas layering, and removing diesel fumes and dust levels from development headings, stopes, and services facilities. The effectiveness of the auxiliary forcing ventilation system depends upon many system variables. Currently, no scientific models and calculations are available that can be used to estimate the optimal distance from the outlet of the auxiliary forcing ventilation system to the development heading in underground mines that can provide the most efficient ventilation close to the face of the heading. In this work, scenarios are developed and simulated with a validated CFD model inside the ANSYS Fluent software. In each scenario, the system parameters such as dead zone, mean age of air, and face velocity are calculated, which are later used in the optimization process. By examining these parameters at the development heading zone, we can quantify the effectiveness of the ventilation system and confirm that the system design meets the government regulations. This work is carried out using the k-epsilon realizable turbulent model inside the ANSYS Fluent software.
R. Koner
Abstract
The Wardha valley coalfields, situated in the western part of India, contribute to more than 7% of the national coal production. The open-pit mining methods are the modes of exploitation of coal in the majority of the mines in the area. Due to the increased depth of working and higher stripping ...
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The Wardha valley coalfields, situated in the western part of India, contribute to more than 7% of the national coal production. The open-pit mining methods are the modes of exploitation of coal in the majority of the mines in the area. Due to the increased depth of working and higher stripping ratio, the output of waste overburden is increased. The challenges are the scarcity of the available land for dumping waste overburden geo-material safely. Optimization of the mine dump slope geometry is the only available alternative in the hands of the management in order to increase the life of the projects and continue the production of coal. This investigation specifically addresses this issue, and proposes a combination of the optimum geometric configurations of the dump slope. This work utilizes the computational power of the numerical modeling technique in order to solve a large number of alternatives and zero them down to the optimum combination. The numerical modeling is considered as a major external factor that contributes to the mine dump's instability. This work shows an 18% increase in the dumping waste material volume in the present condition. This investigation also reveals that double stage dumping is comparably better in optimizing the dump slope configuration.
Muhammad Junaid; Rini Asnida Abdullah; Radzuan Sa'ari; Wahid Ali; Amber Islam; Mahmut Sari
Abstract
This research work aims to critically analyze the efficacy of inexpensive and rapid 2D electrical resistivity tomography (2D ERT) survey for sub-surface geological delineation of granite deposits. The research work involves six ERT profiles using the Schlumberger protocol with an inner and outer electrode ...
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This research work aims to critically analyze the efficacy of inexpensive and rapid 2D electrical resistivity tomography (2D ERT) survey for sub-surface geological delineation of granite deposits. The research work involves six ERT profiles using the Schlumberger protocol with an inner and outer electrode spacing of 5 m and 10 m, respectively. In addition, the unmanned aerial vehicle (UAV) survey is also performed to obtain the terrain information of the studied area. At the same time, a few boreholes are drilled to validate the 2D ERT interpretations. The 2D ERT survey reveals that strong resistivity contrast enables inverted resistivity imaging to characterize the deposit such as topsoil (100-800 Ωm), fracture granite (800-2300 Ωm), and solid granite (> 2300 Ωm). The results obtained from UAV, 2DERT, and borehole survey are further processed to estimate the bedrock to topsoil ratio to assess the feasibility of the deposit. The bedrock to topsoil ratio, estimated by 2D ERT and borehole, is 3.2 and 2.2, respectively. At the same time, the combined UAV, 2D ERT, and borehole survey calculates the bedrock volume 3.2 times to topsoil. Thus the research work allows us to conclude that 2D ERT is an inexpensive, viable, and efficient technique for sub-surface geological documentation, and helps select appropriate mining methods.
A. Owolabi
Abstract
In this paper, we report a geospatial assessment of the selected mine sites in the Plateau State, Nigeria. The aim of this work is to determine the impact of mining on the terrain as well as the Land Use/Land Cover (LULC) of the host communities. The Shuttle Radar Topographic Mission (SRTM) is used for ...
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In this paper, we report a geospatial assessment of the selected mine sites in the Plateau State, Nigeria. The aim of this work is to determine the impact of mining on the terrain as well as the Land Use/Land Cover (LULC) of the host communities. The Shuttle Radar Topographic Mission (SRTM) is used for the terrain mapping. The derived impact of mining on LULC between 1975 and 2014 is determined by classifying the relevant Landsat imageries. The digital terrain map reveal that the mining activity is not well-coordinated. Hence, the parts of the mine sites that are rich in the desired minerals are punctuated with low depth, while the other parts have high terrain as a result of the haphazard mining activity. The analysis of the LULC change show that the degraded land (DL), built-up area (BU), water bodies (WB), and exposed rock outcrop (RO) increase by 15.68%, 4.68%, 0.06%, and 14.5%, respectively, whereas the arable farmland (FL) and forest reserve (FR) decrease by 28.29% and 6.63%, respectively. Mining has adversely affected the natural ecology of the studied area. Therefore, the mine sites should be monitored, and their environmental damages should be pre-determined and mitigated. There should be regular inspections to keep these activities under control. The existing laws and regulations to conserve the natural ecosystems of the host communities should be enforced to curtail the excesses of the operators of the mining industries. Restoration of the minefields to reduce the existing hazards prevent further environmental degradation, and facilitating the socio-economic development of the area is also suggested.
Exploration
Ahmed Abdelhalim; Islam Abuelella; Shawky M Sakran; Said Mohamed Said
Abstract
Kharit basin is an interior Cretaceous rift basin hosted in a Precambrian basement complex of the Arabian-Nubian shield. Satellite images and potential geophysical data previously outlined the basin without a detailed field study. Kharit area is a remote and hyper-arid area; therefore, the application ...
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Kharit basin is an interior Cretaceous rift basin hosted in a Precambrian basement complex of the Arabian-Nubian shield. Satellite images and potential geophysical data previously outlined the basin without a detailed field study. Kharit area is a remote and hyper-arid area; therefore, the application of remote sensing is essential for completing the process of its geo-structural mapping. A multi-spectral optical dataset of the Landsat-8 and high-resolution images of Google Earth was integrated with the field investigation to classify the lithological units and define structures. That integration between analyzed satellite images and field investigations led to a geological map of a minimum scale of 1:50,000 for the lithological rock units and a maximum scale of up to 1:7000 for the structural mapping. The map shows an elongated NW-oriented rift basin filled by a thick deposit of Cretaceous sequences bounded from the east, west, and south by Proterozoic igneous and metamorphic rocks. Additionally, rift-related volcanic rocks were mapped along the western border fault system of the basin. The main mapped faults were delineated in three trends, NW-SE, WNW-ENE, and N-S, while several folds of NW orientations are developed as a normal drag of the main bounding faults. The Early Cretaceous extension along inherited Precambrian lineaments propagated this fault pattern and its associated folds. These structural elements configured the studied area architecture as several grabens with thick Cretaceous sequences.
Rock Mechanics
Pankaj Bhatt; Anil Kumar Sinha; Mariya Dayana P J; Parvathi Geetha Sreekantan; Murtaza Hasan
Abstract
The rapid development of road networks needs huge construction materials. Mining and industrial wastes can be used as sustainable road construction materials and will be alternatives to fulfill the huge demand in road construction. Zinc tailing is one such mining waste and has the potential for road ...
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The rapid development of road networks needs huge construction materials. Mining and industrial wastes can be used as sustainable road construction materials and will be alternatives to fulfill the huge demand in road construction. Zinc tailing is one such mining waste and has the potential for road construction. This material was collected from Zawar mines (Rajasthan), and characterization was carried out for embankment/subgrade applications. A physical model test was conducted in the laboratory to examine the stress-settlement behaviour. To improve the modulus value of tailing, it was reinforced with geogrid in two different laying patterns, viz. layer/loop and stress-settlement behavior was studied. Different parameters were studied: reinforcement depth, layer of reinforcement, number of loops, and depth of loop of reinforcement. The experimental result was validated with the numerical finite element method (SoilWorks). Tailing comprises fine-grained silt-size particles (61%) with no swelling behavior and non-plastic nature. It has values of MDD and OMC as 1.86 g/cm3 and 11%, respectively. It has a higher value of CBR (12%) and internal friction angle (34.6o) with cohesionless nature. The variation of settlement with stress is linear for reinforced and unreinforced tailing fill. As the depth of reinforcement increases, settlement increases in both layer and loop reinforcement. The settlement trajectory obtained from a numerical method closely resembles that of a laboratory physical model, particularly when the applied stress is up to 600 kPa. The modulus of elasticity of tailing was significantly improved with the introduction of geogrid reinforcement either in layer or loop.
N. I. Aziz; I. Porter; F. Sereshki
Abstract
The volumetric changes in the coal matrix (Coal Shrinkage), permeability under various gas environment conditions as well as perographical properties were studied in the laboratory. The shrinkage and permeability of coal were examined with respect to changing gas type and confining pressures. The shrinkage ...
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The volumetric changes in the coal matrix (Coal Shrinkage), permeability under various gas environment conditions as well as perographical properties were studied in the laboratory. The shrinkage and permeability of coal were examined with respect to changing gas type and confining pressures. The shrinkage tests were carried out in high-pressure bombs while the permeability study was conducted in a specially constructed high-pressure chamber. Methane (CH4), carbon dioxide (CO2), nitrogen, (N2) and a 50% -50% volume mixture of CO2/CH4 gas were used in the study. The tests showed that under different pressure levels gas type affected permeability and shrinkage characteristics of coal. This paper presents a case study of Tahmoor Colliery, NSW, Australia and an overall discussion on coal shrinkage, permeability and coal petrography data of Tahmoor that permits a better understanding of the gas regime in this mine. The results are important to the further understanding of the inter-relationship between gas flow, the coal matrix and permeability in ‘normal’ and ‘tight’ coal conditions (locally referred to as disturbed coal).
S. R. Torabi; M. Ataei; M. Javanshir
Abstract
A literature review revealed that most of the empirical equations introduced for determination of the uniaxial
compressive strength (UCS) of rocks based on the Schmidt hammer rebound number (N) are not sufficiently
reliable mostly due to the relatively low coefficient of correlations. This is ...
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A literature review revealed that most of the empirical equations introduced for determination of the uniaxial
compressive strength (UCS) of rocks based on the Schmidt hammer rebound number (N) are not sufficiently
reliable mostly due to the relatively low coefficient of correlations. This is attributed to the fact that in most
cases one formula is used for all types of rocks, although the density of rocks is introduced to the formulae in
some cases. On the other hand, if one specific relationship between N and UCS is introduced for one rock
type, the equation will yield a much higher coefficient of correlation. During a research program supported
by the Shahrood University of Technology, Iran, a third type of approach was considered. The study aimed
to establish a relationship between N and UCS of a rock mass under particular geological circumstances. As
an example, in this study, the immediate roof rock of coal seams in North-Eastern coal fields of Iran was
selected. In order to determine the N and UCS, a significant number of samples were selected and tested,
both in-situ and in the laboratory, and a new equation was established. The equation can be used to predict
UCS of the roof rock in coal extracting areas in this zone by performing simple in-situ Schmidt hammer
tests. It is predicted that such a procedure will be feasible for other geological conditions.
M. Behnia; K. Goshtasbi; M. Fatehi Marji; A. Golshani
Abstract
Numerical methods such as boundary element and finite element methods are widely used for the stress analysis in solid mechanics. This study presents boundary element method based on the displacement discontinuity formulation to solve general problems of interaction between hydraulic fracturing and discontinuities. ...
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Numerical methods such as boundary element and finite element methods are widely used for the stress analysis in solid mechanics. This study presents boundary element method based on the displacement discontinuity formulation to solve general problems of interaction between hydraulic fracturing and discontinuities. The crack tip element and a higher order boundary displacement collocation technique are used to study the hydraulic fracture propagation and its interaction with the pre-existing cracks and discontinuities in an elastic rock mass. The maximum tangential stress criterion (or -criterion) and the strain energy density criterion (SED) are used to obtain the fracture path and the results of both criteria are compared with each other. The comparison of numerical method with the results brought in the literature shows a good performance of the method in the case of interacting cracks.
Kh. Maroufi Naghadehi; A. Hezarkhani; K. Seifpanahi Shabani
Abstract
Taknar deposit is located about 28 km to the north-west of Bardaskan in the Khorasan-e-Razavi province, which is situated in the north-eastern part of Iran. This deposit is unique, formed within the Taknar formation in the Ordovician time. As a result, it is of much interest to many researchers working ...
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Taknar deposit is located about 28 km to the north-west of Bardaskan in the Khorasan-e-Razavi province, which is situated in the north-eastern part of Iran. This deposit is unique, formed within the Taknar formation in the Ordovician time. As a result, it is of much interest to many researchers working in this field. By choosing the lithogeochemical study performed to recognize new exploration targets which a new stage in the field. After pre-processing the lithogeochemical data obtained, the distribution maps were obtained for the element anomalies and alteration indices. The ratios of additive composite haloes were used to study the erosion levels in the Taknar area. In order to produce the favorability map, eight information layers were integrated using the simple overlay method, and four new exploration targets were obtained.
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.
Maysam Abedi; Kiomars Mosazadeh; Hamid Dehghani; Ahmad MadanchiZare
Abstract
This paper describes an efficient edge-preserved regularization algorithm for downward continuation of magnetic data in detection of unexploded ordnance (UXO). The magnetic anomalies arising from multi-source UXO can overlap at a height over the ground surface, while causative sources may not be readily ...
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This paper describes an efficient edge-preserved regularization algorithm for downward continuation of magnetic data in detection of unexploded ordnance (UXO). The magnetic anomalies arising from multi-source UXO can overlap at a height over the ground surface, while causative sources may not be readily separated due to low level of signal-to-noise ratio of the observed data. To effectively the magnetic method work in the cleanup stage of contaminated area with UXO, the magnetic anomalies of UXO sources should be enhanced in order to separate the locations of different sources. The stable downward continuation of magnetic data can increase the signal-to-noise ratio which subsequently causes the separation of UXO sources by enhancing the signals. We formulate the downward continuation as a linear ill-posed deconvolution problem in this study. To obtain a reasonable downward continued field, it is stabilized in a Fourier domain to regularize the downward solution using the edge-preserved (or total-variation) algorithm. The L-curve method is used to choose the optimum value of the regularization parameter which is a trade-off between the misfit and the solution norms in the cost function of optimization problem. A synthetic magnetic field is constructed from isolated multi-source UXO anomalies, whose results show that the data can be stably downward continued by the proposed method. Likewise, a field data set has been provided to demonstrate the capability of the applied method in UXO detection.
H. Mohammadi; M. A. Ebrahimi Farsangi; H. Jalalifar; A. R. Ahmadi; A. Javaheri
Abstract
In advance longwall mining, the safety of mine network, production rate, and consequently, economic conditions of a mine are dependent on the stability conditions of gate roadways. The gate roadway stability is a function of two important factors: 1) characteristics of the excavation damaged zone (EDZ) ...
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In advance longwall mining, the safety of mine network, production rate, and consequently, economic conditions of a mine are dependent on the stability conditions of gate roadways. The gate roadway stability is a function of two important factors: 1) characteristics of the excavation damaged zone (EDZ) above the gate roadway and 2) loading effect due to the caving zone (CZ) above the longwall working, which can extend the EDZ size. Generally, due to the coal seam dip, the failure possibility of main gate roadway is more severe than tail gate roadway. The aim of this work is to determine the longwall working effect on the EDZ extension above main gate roadway. To achieve this purpose, considering three factors involved in the CZ characteristics, the coal seam properties (dip and thickness) and the geomechanical properties of hangingwall, a new geometrical model is developed. Then, based on the geometrical calculations, a new relationship is presented to determine the working influence coeffiecint. Furthermore, taking into account the new geometrical model, an algorithm is suggested for the stability analysis of main gate roadways. Validation of the new geometrical model is carried out by the instrumentation and monitoring results of a longwall working carried out in the Parvade-2 coal mine of Tabas, Tabas, Iran. The results obtained show that there is a good agreement between the values obtained by the new model and the actual measured values. Finally, a sensitivity analysis is carried out on the effects of pillar width, bearing capacity of support system, and coal seam dip.
Ahmed Abd El-Dayiem Abd El-Fatah; Ahmed Ali Madani; Adel Abd Allah Surour; Mokles Kamal Azer
Abstract
The present work aims to enhance the utilization of Landsat-8 data in geological mapping when they are paired with spectroscopic measurements and field observations. This is applied to map and differentiate the different plutonic rocks in the Gebel El-Bakriyah pluton, a peculiar igneous body in the central ...
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The present work aims to enhance the utilization of Landsat-8 data in geological mapping when they are paired with spectroscopic measurements and field observations. This is applied to map and differentiate the different plutonic rocks in the Gebel El-Bakriyah pluton, a peculiar igneous body in the central Eastern Desert of Egypt. Therefore, we use a combination of remote sensing techniques such as principal component analysis (PCA), band ratios, fusion technique, and spectroscopic measurements to interpret igneous lithologies, and produce a new geologic map of the Gebel El-Bakriyah area. A false-color composite principal component image PC1, PC2, and PC3 in red, green, and blue (RGB) discriminates between alkali feldspar granite, syenogranite, and younger gabbro. In general, the spectral profiles of granites exhibit three distinct absorption features in the 1.4, 1.9, and 2.2 μm wavelength regions. These features are attributed mainly to altered mineral products such as kaolinite, sericite, and chlorite. The spectral profiles of pink and alkali feldspar granites show a broad absorption feature at 0.9 μm, which is attributed to a considerable Fe content. The spectral profiles of fresh, younger gabbros exhibit absorption features around 1 μm and 2.2 μm. A false-color composite image provides the most accurate discrimination of the three varieties of younger granites with band ratios of 7/4, 6/3, and 3/1 in RGB. The data that appear in the present work strengthen the usefulness of Landsat-8 imagery and spectroscopic measurements as a prevailing grouping to discriminate and map Neoproterozoic shield rocks in the Eastern Desert of Egypt.
V.F Navarro Torres; G Zamora Echenique; R.N Singh
Abstract
Hydrographically Bolivian Poopó Lake is located in the basin of Desaguadero River and it has over a dozen main tributary rivers and other smaller rivers with lower flow. The mine water discharge from the abandoned and current mining activities polluted these rivers by carrying heavy metals, dissolved ...
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Hydrographically Bolivian Poopó Lake is located in the basin of Desaguadero River and it has over a dozen main tributary rivers and other smaller rivers with lower flow. The mine water discharge from the abandoned and current mining activities polluted these rivers by carrying heavy metals, dissolved and suspended solids which in turn polluted the Poopó Lake which is considered as an important Lake in this area. The present paper deals with the environmental hazards associated with the mining activities with an objective of determining the environmental quality of the Poopó Lake and its tributary rivers, based on physical-chemical analysis of superficial water and sediment samples. The results of the research show that the Poopó Lake water quality can be classified as highly saline, containing high concentration of dissolved or suspended solid, as well arsenic, lead, cadmium, zinc and other heavy metals exceeding the permissible limits of pollutants. Desaguadero River contributed to the Poopó Lake pollution by 70% arsenic, 64% lead, 4.27% zinc and 2.18% cadmium. Other important pollution contributors are Antequera River by 57 % zinc, 32.9 % cadmium and 0.66% lead, and Huanuni River by 61.2% cadmium, 2.23% lead and 34.3% zinc. Vinto foundry, Kori kollo mine and mainly San José mine polluted the Poopó Lake by arsenic and lead through Desaguadero River. Bolivar and Huanuni mines polluted the Poopó Lake by cadmium and zinc through Antequera and Huanuni Rivers. Additionally the mining activities continue to pollute the Poopó Lake by dissolved and suspended solids transporting through Desaguadero, Antequera and Huanuni rivers.
Omid Saeidi; Ahmad Ramezanzadeh; Farhang Sereshki; Seyed Mohammad Esmaeil Jalali
Abstract
This study aims at presenting a numerical model for predicting grout flow and penetration length into the jointed rock mass using Universal Distinct Element Code (UDEC). The numerical model is validated using practical data and analytical method for grouting process. Input data for the modeling, including ...
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This study aims at presenting a numerical model for predicting grout flow and penetration length into the jointed rock mass using Universal Distinct Element Code (UDEC). The numerical model is validated using practical data and analytical method for grouting process. Input data for the modeling, including geomechanical parameters along with grout properties, were obtained from a case study. The effect of rock mass properties such as joint hydraulic aperture, spacing, trace length, orientation and grout properties as yield stress and water to cement, w/c ratio was considered on grout flow rate and penetration length. To illustrate the effect of aforementioned properties, models were constructed with dimensions of 40×20m. A vertical borehole with diameter of 60mm and 10m depth was drilled in a jointed rock media. The results were in a good agreement with analytical method. It was observed that by increasing joint hydraulic aperture, grouting flow increases using a power law function. The optimum grout penetration observed with joint sets intersection of 40°-60° as experienced in practice. With an increase in joint spacing grout penetration increases around borehole when spacing exceeds two meters it decreases, gradually.
