Mineral Processing
F. Basirifar; M.R. Khalesi; M. Ramezanizadeh; M. Abdollahy; A. Hajizadeh
Abstract
Partition curves are widely used to determine the spiral separator efficiency. In this work, the partition curves were used in order to investigate the particle transportation to concentrate and tailing streams. Simulation of fine particle removal using the size-by-size partition curves showed that the ...
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Partition curves are widely used to determine the spiral separator efficiency. In this work, the partition curves were used in order to investigate the particle transportation to concentrate and tailing streams. Simulation of fine particle removal using the size-by-size partition curves showed that the recovery of gangue particles to concentrate can decrease 8.7%. It also showed that the recovery of valuable particles would increase by 6.5% and reaches 90%. Therefore, pilot-scale tests were conducted to verify the simulations. After removal of fine particles from the feed of spiral separator and treating the removed materials with high-intensity magnetic separator, total mass recovery, iron recovery, and iron grade increased from 71%, 85%, and 54% to 80%, 91%, and 56%, respectively.
Rock Mechanics
M. Zoorabadi
Abstract
Numerical modelling techniques are not new for mining industry and civil engineering projects anymore. These techniques have been widely used for rock engineering problems such as stability analysis and support design of roadways and tunnels, caving and subsidence prediction, and stability analysis of ...
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Numerical modelling techniques are not new for mining industry and civil engineering projects anymore. These techniques have been widely used for rock engineering problems such as stability analysis and support design of roadways and tunnels, caving and subsidence prediction, and stability analysis of rock slopes. Despite the significant advancement in the computational mechanics and availability of high speed computing hardware, the input data and constitutive models remain the main source of errors affecting the reliability of numerical simulations. The problem with the input data has been deepened more by introducing empirical-based methods such as GSI classification to downgrade the rock properties from laboratory scale to field scale. The deformability modulus and strength parameters are the main outputs of these downgrading techniques. Numerical modelling users simply apply these downgrading methods and run the model without considering the real mechanics behind the stress induced failure and deformation around the underground excavations. While to the contrary to the commonly used downgrading methods that produce a constant modulus for rock at all depths, the rock modulus is stress dependent and varies with depth. In addition to this, the mechanism of stress induced displacement is not similar to the deformation of a continuum model simulated with equivalent rock properties. Apart from the mechanical characteristics of rocks, the magnitude and orientation of in-situ stresses are two other important parameters that have significant impacts on stress induced rock fracturing. The impacts of these two parameters have also been neglected in many practical cases. This paper discuss this old fashioned topic in more details with presenting the known facts and mechanics which numerical modelling users ignore them due to the unquestioning acceptance of downgrading methods. It also covers the influence of the stress magnitude and orientation on stress induced rock fracturing.
Exploitation
H.R. Nezarat; Seyed M. E. Jalali; M. Nazari
Abstract
Knowledge of the airflow distribution inside a Tunnel Boring Machine (TBM) can create a safe working environment for workers and machinery. The airflow quality and the related mass flow rate in the ventilation system should be sufficient to dilute gases and remove dust inside the tunnel. In this work, ...
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Knowledge of the airflow distribution inside a Tunnel Boring Machine (TBM) can create a safe working environment for workers and machinery. The airflow quality and the related mass flow rate in the ventilation system should be sufficient to dilute gases and remove dust inside the tunnel. In this work, airflow distribution in the single shield TBM tunnel was studied using computational fluid dynamics. The finite volume-based finite element method was used in the simulation based on the 3D complex geometry of TBM. In order to validate the numerical results, the air velocity inside the Chamshir tunnel was measured experimentally at different sections. With a length of 7050 m and a final diameter of 4.6 m, the Chamshir water transport tunnel is located in the south of Iran. The results obtained show that there is not enough airflow in 59.6% of the TBM space in the current working conditions. In other words, there are many dead zones from the control cabin to the end of gantry 6 in the backup system. Several applicable scenarios were studied to remove the dead zone area and optimize the airflow velocity by employing high capacity jet fan in the ventilation system. The results show that the dead zone volume can be decreased by about 5.21% by increasing the airflow rate of the jet fan.
A. Srivastava; B. Singh Choudhary; M. Sharma
Abstract
Blast-induced ground vibration (PPV) evaluation for a safe blasting is a long-established criterion used mainly by the empirical equations. However, the empirical equations are again considering a limited information. Therefore, using Machine Learning (ML) tools [Support Vector Machine (SVM) and Random ...
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Blast-induced ground vibration (PPV) evaluation for a safe blasting is a long-established criterion used mainly by the empirical equations. However, the empirical equations are again considering a limited information. Therefore, using Machine Learning (ML) tools [Support Vector Machine (SVM) and Random Forest (RF)] can help in this context, and the same is applied in this work. A total of 73 blasts are monitored and recorded in this work. For the ML tools, the dataset is divided into the 80-20 ratio for the training and testing purposes in order to evaluate the performance capacity of the models. The prediction accuracies by the SVM and RF models in predicting the PPV values are satisfactory (up to 9% accuracy). The results obtained show that the coefficient of determination (R2) for RF and SVM is 0.81 and 0.75, respectively. Compared to the existing linear regressions, this work recommends using a machine learning regression model for the PPV prediction.
R. Mikaeil; M. Piri; S. Shaffiee Haghshenas; N. Careddu; H. Hashemolhosseini
Abstract
The noise of drilling in the dimension stone business is unbearable for both the workplace and the people who work there. In order to reduce the negative effects drilling has on the health of the environment, the drilling noise has to be measured, assessed, and controlled. The main purpose of this work ...
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The noise of drilling in the dimension stone business is unbearable for both the workplace and the people who work there. In order to reduce the negative effects drilling has on the health of the environment, the drilling noise has to be measured, assessed, and controlled. The main purpose of this work is to investigate an experimental-intelligent method to predict the noise value of drilling in the dimension stone industry. For this purpose,135 laboratory tests are designed on five types of rocks (four types of hard rock and one type of soft rock), and their results are measured in the first step. In the second step, due to the unpredicted and uncertain issues in this case, artificial intelligence (AI) approaches are applied, and the modeling is conducted using three intelligent systems (IS), namely an adaptive neuro-fuzzy inference system-SCM (ANFIS-SCM), an adaptive neuro-fuzzy inference system-FCM (ANFIS-FCM), and the radial basis function network (RBF) neural network. 75% of the samples are considered for training, and the rest for testing. Several models are constructed, and the results indicate that although there is no significant difference between the models according to the performance indices, the proposed construction of ANFIS-SCM can be considered as an efficient tool in the evaluation of drilling noise. Finally, several scenarios are designed with different input modes, and the results obtained prove that the types of rock and the drill bits are more important than the operational characteristics of the machine.
F. Rastegar; H. R. Nejati; A. Ghazvinian; M. R. Hadei; A. Nazerigivi
Abstract
The tensile strength of rocks plays a noteworthy role in their failure mechanism, and its determination can be beneficial in optimizing the design of the rock structures. Schistose rocks due to their inherent anisotropy in different foliation directions show a diverse strength at each direction. The ...
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The tensile strength of rocks plays a noteworthy role in their failure mechanism, and its determination can be beneficial in optimizing the design of the rock structures. Schistose rocks due to their inherent anisotropy in different foliation directions show a diverse strength at each direction. The purpose of this work was to compare and assess the tensile strength of phyllite, which was obtained in direct and indirect tensile tests in different foliation directions. To this end, several phyllite specimens with different foliation angles (0º, 30º, 45º, 60º, and 90º) related to the loading axis (β) were prepared. Finally, the direct tensile test, diametrical and axial point load tests, Brazilian test, and Schmidt hammer test were conducted on 188 samples. The results of the experimental tests revealed that the maximum and minimum tensile strengths in direct tensile testing tension were directly related to the angles of 0º and 90º. Also it was observed that the Brazilian tensile strength overestimated the tensile strength. Furthermore, an exponential correlation was introduced between the direct tensile strength and the Brazilian tensile strength.
Rock Mechanics
E. Dadashi; A. Noorzad; K. Shahriar; K. Goshtasbi
Abstract
The utilization of the lining type in pressure tunnels is highly dependent on the geological and hydraulic conditions. There are two types of lining, namely concrete and steel lining but steel lining is one of the most expensive arrangements. To decrease the length of steel lining in these tunnels, the ...
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The utilization of the lining type in pressure tunnels is highly dependent on the geological and hydraulic conditions. There are two types of lining, namely concrete and steel lining but steel lining is one of the most expensive arrangements. To decrease the length of steel lining in these tunnels, the concrete lining, which prevents water seepage from the surrounding rock mass, is the appropriate alternative. In this work, a special attention is devoted to limit water losses in the concrete lining of pressure tunnel based on the critical reinforcing ratio in concrete lining. In order to evaluate the effect of internal water pressure on the permeability coefficient variation of the concrete lining and the surrounding rock mass, some simulations of reinforced concrete lining is implemented in the ABAQUS finite element software based on the coupled pore fluid-stress analysis. The results obtained indicate that although the critical reinforcing ratio has an important role in capturing the seepage flows and water losses, it is not sufficient to rely only on this parameter. However, among the various influential factors involved, a suitable arrangement of the reinforcement in the concrete lining should also be considered.
Environment
H. Nikoogoftar; A. Hezarkhani
Abstract
In this paper, we aim to achieve two specific objectives. The first one is to examine the applicability of the Artificial Neural Networks (ANNs) technique in ore grade estimation. Different training algorithms and numbers of hidden neurons are applied to estimate Cu grade of borehole data in the hypogene ...
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In this paper, we aim to achieve two specific objectives. The first one is to examine the applicability of the Artificial Neural Networks (ANNs) technique in ore grade estimation. Different training algorithms and numbers of hidden neurons are applied to estimate Cu grade of borehole data in the hypogene zone of porphyry copper-gold deposit, Masjed-Daghi, East Azerbaijan Province (Iran). The efficacy of ANNs in function-learning and estimation is compared with ordinary kriging (OK). As the kriging algorithms smooth the data, their applicability in the pre-processing of data for fractal analysis is not conducive. ANNs can be introduced as an alternative for this kind of problem. Secondly, we aim to delineate the potassic and phyllic alteration regions in the hypogene zone of Cu-Au porphyry deposit based on the estimation obtained by the ANNs and OK methods, and utilize the Concentration-Volume (C-V) fractal model. In this regard, at first, C-V log-log is generated based on the ANN results. The plots are then used to determine the Cu threshold values for the alteration zones. To investigate the correlation between the geological model and C-V fractal results, the log ratio matrix is applied. The results obtained show that Cu values less than 0.38% from ANNs have more overlapped voxels with phyllic alteration zone by an overall accuracy of 0.72. Spatial correlation between the potassic alteration zones resulting from 3D geological modeling and high concentration zones in C-V fractal model show that Cu values greater than 0.38% have more voxels overlapped with the potassic alteration zone by an overall accuracy of 0.76. Generally, the results obtained show that a combination of the ANNs and C-V fractal methods can be a suitable and robust tool for quantitative modeling of alteration zones instead of the qualitative methods.
K. Sultan shah; M. H. bin Mohd Hashim; H. Rehman; K. S. bin Ariffin
Abstract
Indirect tensile testing is used in order to investigate the effect of particle morphology (shape and size) on the various weathering grade sandstone fracture characteristics. Several fracture characteristics are discussed in depth in this work including the fracture length (FL), fracture deviation area ...
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Indirect tensile testing is used in order to investigate the effect of particle morphology (shape and size) on the various weathering grade sandstone fracture characteristics. Several fracture characteristics are discussed in depth in this work including the fracture length (FL), fracture deviation area (FDA), fracture angle (FA), and fracture maximum deviation distance (FMDD). A tabletop microscope (TTM) is used to measure the particle morphology. The image analysis techniques induce the uncertainty-related particle shape and size. Therefore, the Monte Carlo simulation (MCS) is used in order to incorporate the inherent uncertainties-related particle morphology. The results obtained reveal that the sandstone fracture angle presents an unclear relationship with the particle shape and size. The effect of particle size on FL is completely obvious, and FL increases with the particle size. In contrast, the particle shape and size have an unclear relationship with the fracture characteristics. Furthermore, the sandstone porosity affects the fracture characteristics, which increase with the weathering grade. Moreover, the findings reveal that the Monte Carlo simulation is a viable tool for integrating the inherent uncertainties associated with the particle shape and size.
Abderrahim Ayad; Saad Bakkali
Abstract
In Sidi Chennane, Central Morocco, the cost of phosphate mining is often influenced by problems bound to the existence of sterile bodies called derangements. These bodies consisting of a waste rocky material affect the sedimentary phosphate series, and thus disturb the phosphate extraction process. In ...
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In Sidi Chennane, Central Morocco, the cost of phosphate mining is often influenced by problems bound to the existence of sterile bodies called derangements. These bodies consisting of a waste rocky material affect the sedimentary phosphate series, and thus disturb the phosphate extraction process. In this work, we attempt to analyze and quantify the economic impact of these sterile bodies on the cost of phosphate mining in Sidi Chennane. The work is carried out through a prototype model prepared as a real mining trench, using data collected during our internships in the Sidi Chennane mining field. The results of this work show that the cost of removing derangements increases the cost of phosphate mining for the entire cycle of production, drilling, blasting, ripping, dozing, loading, and hauling. It is concluded, therefore, that the outcomes of this work are of great importance for obtaining an accurate understanding of phosphate mining when confronted derangements. This can be adapted to analyze and interpret such similar structures in phosphate mines around the world (e.g. Taïba phosphate mine in Senegal).
A. Ghanizadeh Zarghami; K. Shahriar; K. Goshtasbi; A. Akbari Dehkharghani
Abstract
Calculation of the specific charge and specific drilling before a blasting operation plays a significant role in the design of a blasting pattern and the reduction of the final extraction cost of minerals. In this work, the information from the Sungun, Miduk and Chah-Firouzeh copper mines in Iran was ...
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Calculation of the specific charge and specific drilling before a blasting operation plays a significant role in the design of a blasting pattern and the reduction of the final extraction cost of minerals. In this work, the information from the Sungun, Miduk and Chah-Firouzeh copper mines in Iran was assessed, and it was found that there was a significant relationship between the specific charge and specific drilling and the hole diameter, bench height, uniaxial compressive strength and joint set orientation. After finding a technical and economic model to calculate the specific charge and specific drilling, this model was tested on the Sungun copper mine. Due to the insufficient consideration during the design of a blast pattern and because of the high hardness of the rocks in some parts of the mine, lots of destructive events such as boulders, back break, bench toe, high specific charge and high specific drilling, fly rock, and ground vibration in the blast operations were observed. The specific charge and specific drilling were found to be the most important technical and economic parameters involved in designing a blasting pattern, and they were found to play an important role in reducing the blasting cost. The blasting cost could be largely controlled by the accurate examination and computation of these parameters. An increase in the rock strength and the angle between the bench face and the main joint set would increase the specific charge and specific drilling. On the other hand, a specific charge and a specific drilling would decrease when the hole diameter increased in every range of the uniaxial compressive strength.
M. Kor; E. Abkhoshk; Kh. Gharibie; S. Z. Shafaei
Abstract
An attempt has been made in this paper to investigate the effect of particle size distribution on coal flotation kinetics. The effect of particle size (Ps) on kinetics constant (k) and maximum theoretical flotation recovery (RI) was investigated while other operational parameters were kept constant. ...
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An attempt has been made in this paper to investigate the effect of particle size distribution on coal flotation kinetics. The effect of particle size (Ps) on kinetics constant (k) and maximum theoretical flotation recovery (RI) was investigated while other operational parameters were kept constant. The relationship between flotation kinetics constant and theoretical flotation recovery with particle size was estimated with nonlinear equations. Analysis of variance showed that the effect of particle size on the kinetics constant was statistically significant at 95% confidence level. However, it was not significant on maximum theoretical flotation recovery (RI). Different regression methods were conducted in order to model the effect of coal particle size on flotation kinetics. Results indicated that the quadric regression method gave better prediction of the cumulative recovery for different particle size fractions. The correlation coefficient (R2) values of this model were 0.99, 0.996, 0.98, 0.98 and 0.97 for average of particle sizes of 37.5 µm, 112.5 µm, 225 µm, 400 µm and 625 µm respectively.
A. H. Ansari; K. Alamdar
Abstract
Potential field methods such as gravity and magnetic methods are among the most applied geophysical methods in
mineral exploration. A high-resolution technique is developed to image geologic boundaries such as contacts and faults.
Potential field derivatives are the basis of many ...
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Potential field methods such as gravity and magnetic methods are among the most applied geophysical methods in
mineral exploration. A high-resolution technique is developed to image geologic boundaries such as contacts and faults.
Potential field derivatives are the basis of many interpretation techniques. In boundary detection, the analytic signal
quantity is defined by combining the values of horizontal and vertical derivatives. The outlines of the geologic
boundaries can be determined by tracing the maximum amplitudes of analytic signal. However, due to superposition
effects, in some cases that a variety of sources are adjacent, the detected boundaries are blurred. To overcome this
problem, this study used enhanced analytic signal composed of the nth- order vertical derivative of analytic signal. The
locations of its maximum amplitudes are independent of magnetization direction and geomagnetic parameters. This
technique is particularly suitable when interference effects are considerable and when remanent magnetization is not
negligible. In this paper this technique has been applied to gravity data of southwest England. Using this method, five
granites outcrops and their separating faults are enhanced accurately.
P. Masoudi; B. Tokhmechi; A. Zahedi; M. Ansari Jafari
Abstract
Distinguishing productive zones of a drilled oil well plays a very important role for petroleum engineers to decide where to perforate to produce oil. Conventionally, net pay zones are determined by applying a set of cut-offs on perophysical logs. As a result, the conventional method finds productive ...
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Distinguishing productive zones of a drilled oil well plays a very important role for petroleum engineers to decide where to perforate to produce oil. Conventionally, net pay zones are determined by applying a set of cut-offs on perophysical logs. As a result, the conventional method finds productive intervals crisply. In this investigation, a net index value is proposed, then; diffusivity equation is utilized to calculate the proposed index value. The new net determination method is applied on the interval of Sarvak Formation of two datasets of two nearby wells. The best advantage of this newly developed net determination method is its fuzzy output. Fuzzy net pay determination is valuable in grading pay zones and not classifying all productive zones in a single class. Another advantage of the proposed net determination method is its higher accuracy in identifying productive zones in comparison with cut-off based method.
vahab sarfarazi; Mohammad Omidi manesh; nima babanouri; amir rezaei
Abstract
This work presents the hollow center cracked disc (HCCD) test and the cracked straight through Brazilian disc (CSTBD) test of oil well cement sheath using the experimental test and Particle Flow Code in two-dimensions (PFC2D) in order to determine mode I fracture toughness of cement sheath. The tensile ...
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This work presents the hollow center cracked disc (HCCD) test and the cracked straight through Brazilian disc (CSTBD) test of oil well cement sheath using the experimental test and Particle Flow Code in two-dimensions (PFC2D) in order to determine mode I fracture toughness of cement sheath. The tensile strength of cement sheath is 1.2 MPa. The cement sheath model is calibrated by outputs of the experimental test. Secondly, the numerical HCCD model and CSTBD model with diameter of 100 mm are prepared. The notch lengths are 10 mm, 20 mm, 30 mm, and 40 mm. The tests are performed by the loading rate of 0.018 mm/s. When the notch length in CSTBD is 40 mm, the external work is decreased 48%, related to the maximum external work of model with notch length of 10 mm (0.225 KN*mm decreased to 0.116 KN*mm). When the notch length in HCCD is 30 mm, the external work is decreased 33%, related to the maximum external work of model with notch length of 10 mm (0.06 KN*mm decreased to 0.04 KN*mm). The fracture energy is largely related to the joint length. The fracture energy is decreased by increasing the notch length. In constant to the notch length, the fracture energy of the CSTBD model is more than the HCCD model. Mode I fracture toughness is constant by increasing the notch length. The HCCD test and the CSTBD test yield a similar fracture toughness due to a similar tensile stress distribution on failure surface. The experimental outputs are in accordance to the numerical results.
A Igder; Ali Akbar Rahmani; Ali Fazlavi; Mohammad Hossein Ahmadi; Mohammad Hossein Ahmadi Azqhandi; Mohammad Hassan Omidi
Abstract
The main objective of the present study is to investigate the feasibility of using Carboxymethyl chitosan magnetic nanoparticles (CCMN) for the adsorption of Cd2+. The study also reports important parameters, which affect the adsorption process, i.e., pH, adsorbent dose, contact time and concentration ...
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The main objective of the present study is to investigate the feasibility of using Carboxymethyl chitosan magnetic nanoparticles (CCMN) for the adsorption of Cd2+. The study also reports important parameters, which affect the adsorption process, i.e., pH, adsorbent dose, contact time and concentration of Cd2+, using Box-Behnken designs. Firstly, functional carboxymethyl chitosan magnetic nanoparticles (about 33 nm) was prepared by chemical coprecipitating and characterized by means of scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR). Then, CCMN was used as the adsorbent for the treatment of effluent. The ANOVA result of the full model shows that pH, adsorbent dosage and metal concentration had a significant effect on metal removal. In addition, this parameters indicates which contact time variable does not have a significant effect (p>0.05).
Saeed Alishahi; Ahmad Darban; Mahmood Abdollahi
Abstract
Since a high toxicity of cyanide which use as a reagent in the gold processing plant, thiosulfate has been recognized as a environmental friendly reagent for leaching of gold from ore. After gold leaching process it's important for recovery of gold from solution using adsorption or extraction methods, ...
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Since a high toxicity of cyanide which use as a reagent in the gold processing plant, thiosulfate has been recognized as a environmental friendly reagent for leaching of gold from ore. After gold leaching process it's important for recovery of gold from solution using adsorption or extraction methods, One of these methods is activated carbon.The loading of gold from industrial thiosulfate solution that obtained from Zarshuran gold plant-Takab-Iran, onto activated carbon have been investigated. The affecting variables of the adsorption of gold on the carbon included, temperature, concentration of gold, size of activated carbon, pH and the ratio of amount of activated carbon to the volume of solution. The results have shown that at low concentration of gold, effective loading can be achieved at pH 10.5. The size of activated carbon has a significant effect on the loading of gold. In this research the recovery of gold on activated carbon has been predicted using artificial neural network. For this purpose temperature, pH, the proportion of solution volume to weight of activated carbon, gold concentration and time of adsorption were taken as input parameters, whereas, the recovery of gold on activated carbon from thiosulfate solution was considered as an output parameter. The network with LMBP algorithm with two hidden layer were used and the topology 5-4-13-1 showed the best ability for prediction.Moreover sensitive analyze were indicated parameters pH and temperature have substantial influence on adsorption.
M. Fakhrerad; A. Nejati Kalateh; S. Ghomi
Abstract
Coastal Fars gravimetry project in Fars province was carried out to find the buried salt domes and to determine characteristics of faults in this area. The Lavarestan structure was covered by 4203 gravimetry stations in a regular grid of 1000*250 m. Depth structural model of this anticline made in previous ...
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Coastal Fars gravimetry project in Fars province was carried out to find the buried salt domes and to determine characteristics of faults in this area. The Lavarestan structure was covered by 4203 gravimetry stations in a regular grid of 1000*250 m. Depth structural model of this anticline made in previous studies was based on geological evidences and structural geology measurements. In order to have a complete coverage of Lavarestan anticline, 4 profiles with appropriate intervals were selected on gravity data for further processing and interpretation. 2D inverse modeling was performed on these profiles using Encome Modelvision and Encome PA software. Geometrical and physical parameters of each layer were changed step by step and forward gravity calculations were repeated until we reached a desirable fitting between observed and calculated gravity anomaly. The results of 2D gravity modeling were focused on Lower Paleozoic and Kazerun (cap rock) top horizon, also the underground contour map was extracted from seismic data after interpretation. The results show appropriate correlation between the underground contour map of 2D gravity modeling and interpretation of seismic data.
Gh. Mojarradi; R. Rezaei; A. Ketabi
Abstract
This descriptive analytical survey was aimed to study the negative impacts of mine exploitations carried out in the rural regions of the Tekab Township located in Iran. The statistical population of the studied areas consisted of all the heads of the rural households in the villages located in the vicinity ...
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This descriptive analytical survey was aimed to study the negative impacts of mine exploitations carried out in the rural regions of the Tekab Township located in Iran. The statistical population of the studied areas consisted of all the heads of the rural households in the villages located in the vicinity of the mines in the Tekab Township (N=2680). According to the Cochran formula, a sample size of 220 was selected using a stratified random sampling technique (n=220). A questionnaire was used to collect the data required. The validity of the questionnaire used was confirmed by a panel of experts. A pilot study was conducted to establish the reliability of the instrument used. The Cronbach’s alpha coefficient for the main scale of the questionnaire including the negative effects of the mine exploitations was equal to 0.94. The results obtained from the factor analysis revealed that five factors including the environmental, social, economic, cultural, and hygiene factors explained 60.19% of the total variances of the negative impacts of the mine exploitations in the rural regions of the Tekab Township.
Rock Mechanics
M. T. Hamzaban; H. Memarian; J. Rostami
Abstract
Rock abrasivity is an essential factor for selecting cutting tools, estimating tool wear and life, and ultimately, matching various mechanized excavation systems with a given geologic condition. It also assists engineers to determine economic limits of different cutting tools and machines used in civil ...
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Rock abrasivity is an essential factor for selecting cutting tools, estimating tool wear and life, and ultimately, matching various mechanized excavation systems with a given geologic condition. It also assists engineers to determine economic limits of different cutting tools and machines used in civil and mining projects. The Cerchar abrasion test is a simple and most widely used method for rock abrasivity assessments. However, it has some shortcomings to describe the steel-rock interaction during the cutting process. In this work, two new parameters are used to describe the pin-rock interaction in the Cerchar abrasion test and to evaluate the efficiency of the rock scratching process. A set of 41 different rock samples are tested by a newly developed testing device. The device provides a more precise control of the testing operational parameters, and measures the applied frictional force on the pin and its horizontal and vertical displacements on the sample surface. The results obtained are used to calculate the Modified Cerchar Abrasion Index (MCAI) and the Scratch Energy Index (SEi), as two newly developed parameters. The accuracy of the calculated parameters is discussed. Our investigations show that MCAI has closer correlations with rock mechanical parameters than CAI, and therefore, has a higher potential to estimate the rock cutting tool wear in tunneling applications. Also SEi shows sensible correlations with sample hardness and mechanical properties. The results obtained show that SEi can be used to compare the efficiency of various pin hardnesses to create scratches on various rock samples, and could be used as a determinative parameter in selecting the cutting tool hardness.
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.
Rock Mechanics
A. Asgari; A. Ramezanzadeh; Seyed M. E. Jalali; B. Brouard
Abstract
Ensuring the stability and integrity of underground gas storage salt caverns is a very complicated subject due to the non-linear and time-dependent behavior of rock salts under complicated thermal and mechanical loading conditions. For this reason, pressure and temperature fluctuations in the caverns ...
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Ensuring the stability and integrity of underground gas storage salt caverns is a very complicated subject due to the non-linear and time-dependent behavior of rock salts under complicated thermal and mechanical loading conditions. For this reason, pressure and temperature fluctuations in the caverns and their surrounding strata must be integrated into the analysis and the numerical tools that are used for this purpose. LOCAS, a 2D axisymmetric finite-element code, dedicated to the stability analysis of underground salt spaces, was applied to assess the effects of various operating and geometrical parameters on the cavern behavior. In this paper, we aimed to give an overall assessment of the behavior of the salt caverns used for natural gas storage. In this work, some specific loading scenarios were considered first, followed by thorough parametric and sensitivity analyses to reveal the impacts of the geometrical parameters and operational parameters involved on the behavior of salt caverns using the modern stability criteria. The findings showed that the onset of dilation was more likely to happen within the first cavern life cycle when pressure dropped to the minimum level. As for the potential of tension occurrence in the surrounding rock, this is more likely to happen by increasing the number of operation cycles, especially in the upper one-third of the cavern wall. Finally, it was seen that the cavern depth and minimum cavern internal pressure had even more important influences than the others on the salt cavern behavior.
N. M. Shahani; M. J. Sajid; I. M. Jiskani; B. Ullah; A. R. Qureshi
Abstract
In this work, we employ the fuzzy logic technique to achieve and present, for the first time, a proper analysis of the actual intensity of the increase in the coal miners’ fatality rates in Pakistan from 2010 to 2018, compared with China and India, with an objective to minimize the impact of incidents ...
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In this work, we employ the fuzzy logic technique to achieve and present, for the first time, a proper analysis of the actual intensity of the increase in the coal miners’ fatality rates in Pakistan from 2010 to 2018, compared with China and India, with an objective to minimize the impact of incidents on the miners’ fatalities. The average and yearwise fatality rates in Pakistan, compared with China and India, are used for the fuzzy logic technique in order to calculate the actual degree of flexibility for the surging fatalities. The findings show that both the average (2010-2018) and yearwise fatality rates in 2011, 2015, and 2018 are 2.44, 1.74, and 1.6, respectively. In the fuzzy logic technique, the variables whose membership function (µ) values are ≥ 1 represent the absolute truth. The membership function values for the years 2011, 2015, and 2018 are alarmingly high for the fatalities of coal miners. Similarly, except for 2014 and 2010, where 0 represents the absolute falseness, the results for the remaining years indicate high fatality rates with a flexibility (or small extent) of its corresponding membership function (µ) values such as 0.623, 0.739, 0.219, 0.173 and 0.115, and 0.714, 0.24, 0.01, 0.324 and 0.317 using the average and yearwise analysis, respectively, compared with China. Likewise, the fuzzy logic membership function (µ) values compared with India in the remaining years are 0.704, 0.795, 0.386, 0.159, 0.352 and 0.306, and 0.675, 0.795, 0.386, 0.186, 0.321 and 0.322, respectively. The proposed fuzzy logic analysis has been founded based on the theory of fuzzy sets to properly identify the miners’ fatalities, and also to suggest the implementation of appropriate recommendations to reduce the fatalities in the coal mines in Pakistan.
Deemah Saad Mahmoud; Ahmed Ali Madani; Said Mohamed Said; Mohamed Mokhtar Yehia; Tamer Nassar
Abstract
The eastern border of the Nile valley south of Cairo is distinguished by numerous springs and associated surface water bodies, e.g. Ain El-Sira, Helwan, and Atfih. Except the latter, all of them were disseminated in urban areas, and were hardly detected by remote sensing data. Thus, studying the surface ...
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The eastern border of the Nile valley south of Cairo is distinguished by numerous springs and associated surface water bodies, e.g. Ain El-Sira, Helwan, and Atfih. Except the latter, all of them were disseminated in urban areas, and were hardly detected by remote sensing data. Thus, studying the surface water of Atfih spring is key to understanding the nature of the east Nile spring system. Change in this surface water has been detected based on the integration between the spatiotemporal analysis of the multi-spectral satellite images and the Modern-Era Retrospective Analysis for Research and Applications (MERRA-2) rainfall data from 1987 to 2019, and the field investigation. The normalized differential water index analysis reveals an increase in the surface area of the Atfih water body by two to three times during the years 2016-2017. The results clarified the relationship between the appearance of the surface water of Atfih spring and rainfall amounts. Another factor controlling the Atfih water body treated in this work is the geological structures. A field survey aided by the processed satellite data revealed the presence of three fault populations: WNW-ESE, E-W to ENE-WSW, and NNE-SSW. The E-W to ENE-oriented faults are the main faults and have a right-lateral strike-slip sense of movement. This fault pattern and Pliocene shale have a substantial impact on the appearance of the Atfih water body. These faults act as a horizontal channel that allows lateral movement of meteoric water through Eocene carbonate, and water recharge occurs at the highly fractured strike-slip transfer zones.
Mineral Processing
Y. Kianinia; M. R. Khalesi; M. Abdollahy; A. Khodadadi Darban
Abstract
Processing of gold ores with high sulfide minerals is problematic as they consume cyanide and reduce gold leaching. Optimization of gold leaching and cyanide consumption requires a methodology to estimate the amount of exposed cyanicides, their leaching kinetics, and speciation of cyanide complexes that ...
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Processing of gold ores with high sulfide minerals is problematic as they consume cyanide and reduce gold leaching. Optimization of gold leaching and cyanide consumption requires a methodology to estimate the amount of exposed cyanicides, their leaching kinetics, and speciation of cyanide complexes that consume the free cyanide and compete with gold. In this paper, a physico-chemical approach is presented to estimate the liberation and exposure of cyanicides to the leaching solution, and then prediction of the speciation of all possible related species in the solution. The results obtained show that this methodology not only could successfully estimate the gold leaching and cyanide consumption based on the mineralogical data with a lower number of parameters compared to existing empirical models, but also offers the prediction of formation of all the possible complexes that could be used for optimization purposes.
