Leila Nikakhtar; Shokroallah Zare; Hossein Mirzaei
Abstract
Surface settlement induced by tunneling is one of the most crucial problems in urban environments. Hence, accurate prediction of soil geotechnical properties is an important prerequisite in the minimization of it. In this research work, the amount of surface settlement is predicted using three-dimensional ...
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Surface settlement induced by tunneling is one of the most crucial problems in urban environments. Hence, accurate prediction of soil geotechnical properties is an important prerequisite in the minimization of it. In this research work, the amount of surface settlement is predicted using three-dimensional numerical simulation in the finite difference method and Artificial Neural Network (ANN). In order to determine the real geotechnical properties of soil layers around the tunnel; back-analysis is carried out using the optimization algorithm and monitoring data. Among the different optimization methods, genetic algorithm (GA) and particle swarm optimization (PSO) are selected, and their performance is compared. The results obtained show that the artificial neural network has a high ability with the amounts of R=0.99, RMSE=0.0117, and MSE= 0.000138 in predicting the surface settlement obtained from 150 simulations from randomly generated data. Comparing the results of back-analysis using the optimization algorithm, the genetic algorithm shows less error than the particle swarm algorithm in different initial populations. In all cases of analysis, the calculation time for both algorithms lasts about 5 minutes, which indicates the applicability of both algorithms in optimizing the parameters in mechanized tunneling in a short time.
Rock Mechanics
Vahab Sarfarazi; Lei Zhou; Hadi Haeri; Parastou Salehipour; Ali Elahi; Ali Moayer; Mohammad Fatehi Marji
Abstract
The mechanical behavior of rock-rock bolt interface considering the effects of indents’ shape and their number was numerically simulated based on discrete element method using the two-dimensional particle flow code. The conventional and standard uniaxial compressive and Brazilian tensile strengths ...
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The mechanical behavior of rock-rock bolt interface considering the effects of indents’ shape and their number was numerically simulated based on discrete element method using the two-dimensional particle flow code. The conventional and standard uniaxial compressive and Brazilian tensile strengths tests were used to calibrate the modelled samples with 100 cm 100 cm in dimension. The numerical models were prepared such that different indent shape and number were inserted in the cable bolts arrangements during the rock reinforcement process. The effects of confining pressure 3.7 MPa and different shear failure loads were modeled for the punch shear test of the concrete specimens. The results of this study showed that the dominant failure mode of the rock-cable bolt interface was of tensile mode and the shape and number of cable indents significantly affected the strength and mechanical behavior of the modelled samples. It has also been showed that the indent dimensions and number affected the shear strength of the interfaces.
Environment
Masoud Rabieian; Farhad Qaderi
Abstract
Offshore produced water (OPW), a type of wastewater rich in hazardous compounds such as polycyclic aromatic hydrocarbons (PAHs), requires effective treatment. This study presents a novel methodology utilizing TiO2 nanoparticles, ultraviolet (UV) lamps, and ozonation for the degradation of phenanthrene ...
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Offshore produced water (OPW), a type of wastewater rich in hazardous compounds such as polycyclic aromatic hydrocarbons (PAHs), requires effective treatment. This study presents a novel methodology utilizing TiO2 nanoparticles, ultraviolet (UV) lamps, and ozonation for the degradation of phenanthrene (PHE) from OPW. Various factors including UV lamp power (10W-50W), ozone dose (0.1 mg/L-0.5 mg/L), TiO2 concentration (0.5 g/m²-2.1 g/m²), ethanol fraction (25%-85%), pH (4.5-10.5), PHE initial concentration (5 mg/L-25 mg/L), and treatment time (15 min-45 min) were systematically investigated to understand their impact on PAH degradation in the OPW. The study employs Response Surface Methodology (RSM) for modeling and optimizing PHE removal efficiency. The results contribute to the development of a mathematical model, and through optimization, optimal conditions are proposed to maximize PHE removal efficiency. Experimental implementation of the optimized conditions in a physical model resulted in an impressive 98% PHE removal efficiency. The identified optimal conditions include UV lamp power of 40 W, ozone dose of 0.5 mg/L, TiO2 concentration of 2 g/m², ethanol fraction of 25%, pH of 5.2, initial PHE concentration of 15 mg/L, and a treatment time of 40 min. This optimized approach provides valuable insights for efficient and environmentally friendly treatment of PAHs in OPW, emphasizing on the potential for practical application in soil washing effluent treatment.
R. Dabiri; M. Bakhshi Mazdeh; H. Mollai
Abstract
The aim of this study was to determine the extent of metal pollutions and the identification of their major sources in the vicinity of the Sangan iron mine occurring in NE Iran. Soil samples were collected from the vicinity of the mine site and analyzed for heavy metals. In addition, the chemical speciation ...
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The aim of this study was to determine the extent of metal pollutions and the identification of their major sources in the vicinity of the Sangan iron mine occurring in NE Iran. Soil samples were collected from the vicinity of the mine site and analyzed for heavy metals. In addition, the chemical speciation of these metals was investigated by means of the sequential extraction procedure. The statistical and spatial variability of the metal concentrations and other soil parameters were also analyzed by the multivariate statistical methods (principal component analysis and cluster analysis). Contaminant Factor (CF) and Enrichment Factor (EF) were used to evaluate soil pollution in the samples. By this study, one can conclude that a notable enrichment of heavy metals happened in the margin of the mining area. The data obtained reveal that soils in the area are contaminated, showing higher levels of Fe, Sn, Co, Cu, Sb, S, and Cd in comparison with their normal distributions. The results of sequential extraction analysis and multivariate (geo)statistical methods show that the variability of Fe, Sn, Co, Cu, Sb, S, and Cd is predominately controlled by the anthropogenic source (mining activity), whereas Pb, Cr, and Zn are mainly of natural (geogenic) origin.
Mineral Processing
M. Mohseni; M. Abdollahy; R. Poursalehi; M. R. Khalesi
Abstract
The reactivity of the protonated and hydroxylated sphalerite (1 1 0) surface with xanthate was simulated using the density functional theory (DFT). The difference between the energy of the lowest unoccupied molecular orbital of the sphalerite surface and the energy of the highest occupied molecular orbital ...
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The reactivity of the protonated and hydroxylated sphalerite (1 1 0) surface with xanthate was simulated using the density functional theory (DFT). The difference between the energy of the lowest unoccupied molecular orbital of the sphalerite surface and the energy of the highest occupied molecular orbital of xanthate ( was used to compare the reaction capability of xanthate with fresh and functionalized surfaces. The Mulliken atomic charge analysis was used to provide an in-depth insight into the effects of –H+ and –OH- groups on the reactivity of Zn atoms at the sphalerite surface. The values for different systems showed that the protonated surfaces exposed a higher reactivity with xanthate than the fresh and hydroxylated surfaces. The results of the Mulliken atomic charge analysis demonstrated that after the formation of –H+ and –OH- contained groups on the sphalerite surface, the surface atoms found a new charge due to the reduction and oxidation mechanism. In addition, the results obtained revealed that the electrophilicity of Zn atoms after the ion adsorption could be considered as a key factor in the reactivity of the sphalerite surface with xanthate. The DFT-based calculations also showed that different alkyl groups of xanthate had no significant influence on the reactivity of their head groups. The findings of this research work provided insights into the reactions of the sphalerite surface with xanthate.
Rock Mechanics
E. Bakhshi; V. Rasouli; A. Ghorbani; M. Fatehi Marji
Abstract
In this work, we used a grain-based numerical model based on the concept of lattice. The modelling was done to simulate the lab experiments carried out on the mortar samples. Also the analytical solutions corresponding to the viscosity-dominated regime were used to estimate the fracture length and width, ...
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In this work, we used a grain-based numerical model based on the concept of lattice. The modelling was done to simulate the lab experiments carried out on the mortar samples. Also the analytical solutions corresponding to the viscosity-dominated regime were used to estimate the fracture length and width, and the results obtained were compared with the numerical simulations. As the analytical solutions are proposed for a penny-shaped fracture with no presence of any obstacle such as natural interfaces, in this work, we presented the results of lattice simulations for hydraulic fracturing in the cement sample, similar to the lab, but with no natural fractures, and compared the results obtained with analytical solutions. The results indicated that in the case of a continuous medium, the analytical solutions may present a reasonable estimation of the fracture geometry. Also the viscosity-dominated leak-off model showed a better match between the analytical solutions and the numerical simulation results, confirmed by observing fluid loss into the sample in the lab post-experiment. In the case of assuming leak-off, the results indicated that the fracture width and length would reduce. However, it should be noted that in real cases, rock formations exhibit fractures and inhomogeneity at different scales so that the applications of the analytical solutions are limited.
M. Hosseini Nasab; M. Noaparast; H. Abdollahi
Abstract
In this research work, the bio-leaching of Co and Ni from an iron-rich laterite ore is assessed using the acidophilic heterotrophic (Delftia acidovorans)and autotrophic (Acidithiobacillus ferrooxidans) bacteria. The metabolic products of the acidophilic bacteria play an important role in bio-leaching. ...
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In this research work, the bio-leaching of Co and Ni from an iron-rich laterite ore is assessed using the acidophilic heterotrophic (Delftia acidovorans)and autotrophic (Acidithiobacillus ferrooxidans) bacteria. The metabolic products of the acidophilic bacteria play an important role in bio-leaching. The results obtained from the indirect bio-leaching indicate the highest nickel recoveries of up to 83.65% and 80.18%, respectively, by the supernatants of Acidithiobacillus ferrooxidans and Delftia acidovorans, both measured at 90 °C for 3 h with a stirring speed of 370 rpm and S/L of 0.1, while the corresponding cobalt recovery rates have reached 86.93% and 83.94%, respectively. The iron dissolution rates in these conditions for the two studied bacteria are 64.34% and 54.41%, respectively. The nickel and cobalt extractions by the indirect bio-leaching of Delftia acidovorans are, respectively, 29.84% and 23.75% higher than those for the direct bio-leaching, performed at 30 °C and 150 rpm of an incubator shaker for 30 days. For the indirect bio-leaching, the chemical control has a larger influence on the dissolution rate of the iron-rich laterite compared to the diffusion control. The activation energies of nickel and cobalt in the chemical control model are 40.07 and 39.08 kJ/mol, respectively.
Exploitation
A. Hosseini; M. Najafi; Seyed A. Shojaatlhosseini; R. Rafiee
Abstract
The longwall mining method is one of the most applied methods in extracting low-inclined to high-inclined coal seams. Selection of the most suitable extraction equipment is very important in the economical, safety, and productivity aspects of mining operations. There are a lot of parameters affecting ...
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The longwall mining method is one of the most applied methods in extracting low-inclined to high-inclined coal seams. Selection of the most suitable extraction equipment is very important in the economical, safety, and productivity aspects of mining operations. There are a lot of parameters affecting the selection of an extraction equipment in mechanized longwall mining in steeply inclined coal seams. The important criteria involved are the geometric properties of coal seam (dip, thickness, and uniformity of coal seam), geological and hydraulic conditions (faults, fractures, joints, and underground water), and geomechanical properties of coal seam and surrounding rocks. Extraction of inclined coal seams with gradients greater than 40 degree is different from low-inclined seams, and requires a special equipment. Therefore, the influence of the above-mentioned parameters must be considered simultaneously in the selection of extraction equipment for steeply inclined seams. This paper presents an application of the Fuzzy Analytical Hierarchy Process (FAHP) method in order to select a suitable extraction equipment in the Hamkar coal mine. In the proposed FAHP model, fifteen main criteria are considered, as follow: dip of coal seam, thickness of coal seam, seam uniformity, expansion of coal seam, faults, fractures and joints, underground waters, hangingwall strength, footwall strength, coal strength, in-situ stress, equipment salvage, dilution, system flexibility, and operational costs. Among the 6 considered longwall extraction equipment system alternatives, the findings show that the most suitable extraction equipment system is shearer on footwall and a support system using hydraulic props and the transport of coal with the force of gravity.
M. M. Pourgholam; P. Afzal; A. Adib; K. Rahbar; M. Gholinejad
Abstract
Signal analysis approaches are a powerful and widely used tool in processing multi-spectral satellite images for detection of alteration zones. The main goal of this work is application of the spectrum-area fractal methodology based on the Landsat 8 OLI satellite images’ data for separation alteration ...
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Signal analysis approaches are a powerful and widely used tool in processing multi-spectral satellite images for detection of alteration zones. The main goal of this work is application of the spectrum-area fractal methodology based on the Landsat 8 OLI satellite images’ data for separation alteration zones for iron oxides at the Tarom region (NW Iran). These alteration zones, Normalized Difference Vegetation Index (NDVI), and Normalized Difference Water Index (NWDI) are detected using the band-ratio and band combination methods. Then the calculated values are categorized by Spectral Angle Mapper (SAM), k-means, and S-A fractal model. Considering a positive correlation of iron oxides alterations along with magnetite mineralization as an index of mineralization at the studied region, the promising areas are classified by a decision-making model using the TOPSIS method with an acceptable accuracy for presenting in the exploration models.
R. Siyar; F. Doulati Ardejani; M. Farahbakhsh; M. Yavarzadeh; S. Maghsoudy
Abstract
Copper smelting and refinery factories are the final stages of a pyrometallurgical processing chain, and they cause many environmental challenges around the world. One of the most common environmental problems of these factories is toxic emissions. These toxic gases have harmful effects on the vegetation, ...
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Copper smelting and refinery factories are the final stages of a pyrometallurgical processing chain, and they cause many environmental challenges around the world. One of the most common environmental problems of these factories is toxic emissions. These toxic gases have harmful effects on the vegetation, animal species, soils, and water resources around the factories. Phytoremediation can play an important role in the reduction of the adverse effects of environmental pollutions arising from copper smelting and refinery factories. In this paper, we first discuss different types of pollutions caused by copper metallurgical factories, and present the main research approaches and studies conducted on these factories. In the second part, we provide a summary and comparison of different remediation technologies used to reduce the environmental pollutions of these factories. Besides, the advantages and disadvantages of each method is also investigated. In the third part, we review the different aspects of the phytoremediation including the effective mechanisms, different types of plants, application environments, and the effective factors. The next part includes the selection of suitable plants for the phytoremediation process applied for copper metallurgical factories and investigation of the native and cultivated hyperaccumulator plants. In addition, different efficiency indices are introduced for evaluating the phytoremediation efficiency and selecting an appropriate hyperaccumulator plant. At the final stage, some appropriate plant species for various types of phytoremediation are introduced. The effects of different environmental stresses and the possibilities of integrating phytoremediation with other remediation technologies as well as the advantages and disadvantages of phytoremediation are eventually investigated.
Hadi Bejari; Jafar Khademi Hamidi
Abstract
This work aims to investigate the effect of water saturation on cutting forces and chipping efficiency by performing a series of small-scale linear cutting tests with a chisel pick on twelve low- and medium-strength rock samples. The peak and mean cutting force acting on the chisel pick are measured ...
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This work aims to investigate the effect of water saturation on cutting forces and chipping efficiency by performing a series of small-scale linear cutting tests with a chisel pick on twelve low- and medium-strength rock samples. The peak and mean cutting force acting on the chisel pick are measured and recorded under dry and saturated cutting conditions by the strain sensors that are embedded in the dynamometer. Also the amplitude of cutting force fluctuations in dry and saturated cutting conditions is compared by the standard deviation measurement of cutting force data, and its relationship with the size of cutting fragments is investigated. The results obtained show that the peak cutting force is reduced in saturated conditions compared to dry conditions. The mean cutting force in the synthetic sample cutting test is unchanged or in some cases increase, while in the natural samples it decreases. The relative increase in the mean cutting force in synthetic rock specimens is due to the paste state of fine materials produced from saturated cutting and chisel pick clogging. A strong correlation is found between the standard deviation of cutting force data and the average size of rock debris, indicating that the standard deviation of cutting force data is a useful measure for evaluating the chipping efficiency. The present study's findings reveal that to have an efficient excavation system in field operations, it is necessary to consider the presence of water and saturated conditions in designing the cutting machine's operating parameters and predicting the performance of mechanical excavators.
Exploitation
Shahrokh Khosravimanesh; Masoud Cheraghi Seifabad; Reza Mikaeil; Raheb Bagherpour
Abstract
Specific energy is a key indicator of drilling performance to consider in the feasibility and economic analyses of drilling projects. Any improvement in the specific energy of a drilling operation may reflect an improvement in the overall efficiency of drilling operations. This improvement can be achieved ...
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Specific energy is a key indicator of drilling performance to consider in the feasibility and economic analyses of drilling projects. Any improvement in the specific energy of a drilling operation may reflect an improvement in the overall efficiency of drilling operations. This improvement can be achieved by delivering a suitable cooling lubricant into the drilling environment. The present study examines the mechanical characteristics of the drilled rock, the physical qualities of the cooling lubricant employed, and the drilling rig operational parameters related to the drilling-specific energy (DSE). To this end, seven rock samples (granite, marble, and travertine) were drilled using water and five other fluids as the cooling lubricants. A total of 492 drilling experiments were conducted with a custom-designed and built laboratory-scale drilling rig on cuboid rock specimens. The univariate linear regression analysis of experimental results revealed a significant drop in DSE after using cooling lubricants instead of conventional cooling fluid (i.e. water). Under constant conditions in terms of mechanical properties of the rock, using Syncool with a concentration of 1:100 and soap water with a concentration of 1:120 instead of water led to 34% and 43% DSE reductions in the granite samples, 48% and 54% in the marble samples, and 41% and 50% in the travertine samples, respectively. These variations in specific energy suggest that the drilling efficiency and performance can be augmented using properly selected cooling lubricants.
Rock Mechanics
Mohammad Rezaei; Seyed Zanyar Seyed Mousavi; Kamran Esmaeili
Abstract
This study introduces a novel approach, known as Hybrid Probabilistic Slope Stability Analysis (HPSSA), tailored for Mine 4 of the Gol-E-Gohar iron complex in Iran. The mine walls are first divided into 8 separate structural zones, including A-A' to H-H' sections for slope stability analysis. Then, sufficient ...
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This study introduces a novel approach, known as Hybrid Probabilistic Slope Stability Analysis (HPSSA), tailored for Mine 4 of the Gol-E-Gohar iron complex in Iran. The mine walls are first divided into 8 separate structural zones, including A-A' to H-H' sections for slope stability analysis. Then, sufficient core specimens are prepared from 22 drilled boreholes and the required parameters for slope design, including cohesion (c), friction angle (φ), and unit weight (γ), are measured. Finally, the HPSSA approach is performed through the combination of Monte Carlo simulation (MCS), Mohr-Coulomb criterion and Bishop's technique. According to the HPSSA results, the normal distribution function is achieved as the best curve fit for c, φ and γ parameters. Also, the obtained values of mean probabilistic safety factor (SF) for defined structural zones vary from 0.93 to 1.86, with the probability of failure (PF) of 0 to 75.6%. Moreover, SF values varied from 0.68 to 1.22 (mean value of 0.93) with a PF of 75% for the A-A' section and from 0.65 to 1.24 (mean value of 0.97) with a PF of 60% for the H-H' section. Hence, it is concluded that the A-A' section and mine’s north wall are more prone to instability with PF>60%. On the other hand, SF>1.2 and PF<5% for other mine walls (sections B-B'-G-G') prove that they are highly unlikely to be unstable. Displacement monitoring of the pit walls using installed prisms confirmed that average displacements in structural zones have a similar trend with SF values of the HPSSA. The results show a good agreement between the trend of probabilistic SFs and monitored slope displacements. Lastly, comparative analysis confirmed the validity of the suggested HPSSA approach with relatively higher accuracy than most previous slope stability analysis methods.
Exploitation
A. Aryafar; H. Moeini
Abstract
Anomaly separation using stream sediment geochemical data has an essential role in regional exploration. Many different techniques have been proposed to distinguish anomalous from study area. In this research, a continuous restricted Boltzmann machine (CRBM), which is a generative stochastic artificial ...
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Anomaly separation using stream sediment geochemical data has an essential role in regional exploration. Many different techniques have been proposed to distinguish anomalous from study area. In this research, a continuous restricted Boltzmann machine (CRBM), which is a generative stochastic artificial neural network, was used to recognize the mineral potential area in Korit 1:100000 sheet, located 15 km south of Tabas, South Khorasan Province (East of Iran). For this purpose, 470 geochemical stream sediment samples were collected from the study area and analyzed for 36 elements. In order to achieve the goal, in the first step, the robust factor analysis on compositional data was applied to reduce the data dimension and to limit the multivariate analysis by selecting the main components of mineralization. In this procedure, the third factor (out of 6) consisting of Cu, Pb, Zn, Sn, and Sb, related to the metallogenic properties, was considered as the input set in CRBM. In continuation, the CRBM structure with the best efficiency after trying different parameters was stabilized. High-identified error values or anomalies were exteracted using two different thresholds (ASC and ASE) after training with the whole data and reconstructing it by CRBM. The anomalies were then mapped. These indicated the promissing areas. The field studies and existing mining indices confirmly demonestrated the results obtained by CRBM.
Rock Mechanics
N. Aziz; A. Mirzaghorbanali; G. Yang; S. Khaleghparast; H. Resekh
Abstract
There is an increasing need to determine accurately the strength properties of tendons for an effective ground control on mines and underground structures as well as on modelling simulations. The strength properties of cables, used as cable bolts, have been evaluated mainly by their ultimate tensile ...
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There is an increasing need to determine accurately the strength properties of tendons for an effective ground control on mines and underground structures as well as on modelling simulations. The strength properties of cables, used as cable bolts, have been evaluated mainly by their ultimate tensile strength, as this kind of test can be carried out in the field as well as in the laboratory. Only recently, there has been a growing interest in cable bolt failures in shear because of the documented field failure evidence. Accordingly, this paper reports various methods of shear testing of rock bolts and cables using different shear testing rigs, some have been developed by the rock bolting research team at the University of Wollongong. A programme of shear testing of a variety of cable bolts marketed in Australia was undertaken, the results of which were reported and conclusions were drawn. It was concluded that plain cable bolts were de-bonded during shearing when compared to spiral cables under the same testing conditions. In addition, both the single shear and double shear testing methodologies will result in the same outcome if there is no de-bonding, and a proper confinement is applied.
Mineral Processing
P. Karimi; A. Khodadadi Darban; Z. Mansourpour
Abstract
Low-intensity magnetic separators are widely used in the research works and the industry. Advancement in the magnetic separation techniques has led to an expansion in the application of this method in different fields such as enrichment of magnetic mineral, wastewater treatment, and medicine transfer ...
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Low-intensity magnetic separators are widely used in the research works and the industry. Advancement in the magnetic separation techniques has led to an expansion in the application of this method in different fields such as enrichment of magnetic mineral, wastewater treatment, and medicine transfer in the human body. In the mineral processing industry, the main application of wet magnetic separation is via drum separators. The design of this separator is based on drum rotation inside a tank media, where a permanent magnet placed inside the drum as an angle form produces a magnetic field. In the present work, the magnetic variables involved (magnetic flux density, intensity of magnetic field, and gradient of magnetic field intensity) were simulated in the drum wet low-intensity magnetic separator using the finite element method and a COMSOL Multiphysics simulator; these variables were further validated through the measured data. A comparison between the simulation and laboratory measurements (of the magnetic field) showed that the mean value of the simulation error in 94 points in 2 sections was equal to 9.6%. Furthermore, the maximum simulation error in the middle of the magnets, as the most important part of the magnetic field distribution in the process of magnetic separation, was in the 6th direction and equal to 7.8%. Therefore, the performed simulation can be applied as a first step to design and construct more advanced magnetics separators.
V. Sarfarazi; K. Asgari; Sh. Mohamadi Bolban Abad
Abstract
In this work, we investigate the interaction between tunnel and surface foundation in two dimensions by the particle flow code. At the first stage, the PFC calibration is conducted using the experimental test results rendered by a biaxial test. Then the simulation of a biaxial test is performed by confining ...
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In this work, we investigate the interaction between tunnel and surface foundation in two dimensions by the particle flow code. At the first stage, the PFC calibration is conducted using the experimental test results rendered by a biaxial test. Then the simulation of a biaxial test is performed by confining a rectangular sample inside four walls. The walls are located at the top and bottom simulated loading plates and the adjacent walls are located at the left and right simulated sample side confinement. The velocities of the top and bottom walls are determined, and they are used for loading the sample in a strain-controlled mode. The respond of the material is evaluated by following the diverse stress and strain quantities. The axial deviatoric stress versus the axial strain for biaxial test on the bonded granular material is drawn, and then the Mohr's circle is drawn in order to reach the failure envelope of laboratory. Secondly, a rectangular model with dimensions of 10 m 10 m containing a central tunnel and a surface foundation is built. The tunnel is situated in sixteen different positions below the foundation. The foundation moves downward with a velocity of 0.016 mm/s. The results obtained show the position of the tunnel controlling the failure volume. Also the vertical displacement at the roof of the tunnel decreases by increasing the vertical spacing between tunnel and foundation. The settlement beneath the foundation increases by reducing the vertical spacing between the tunnel and the foundation. The settlement beneath the foundation decreases by augmenting the horizontal spacing between the tunnel and the foundation.
Hossein Mahdiyanfar; Amir Salimi
Abstract
This work aims to investigate the geochemical signatures of the Cu porphyry deposit in the Dalli area using the geochemical soil samples. At the first step, the geochemical data was opened using the Centered Log-Ratio (CLR) transform method. Then those outlier samples that reduce the accuracy of the ...
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This work aims to investigate the geochemical signatures of the Cu porphyry deposit in the Dalli area using the geochemical soil samples. At the first step, the geochemical data was opened using the Centered Log-Ratio (CLR) transform method. Then those outlier samples that reduce the accuracy of the geochemical models were detected and removed using the Mahalanobis Distance (MD) method. We applied the Principal Component Analysis (PCA) and Geochemical Mineralization Prospectivity Index (GMPI) methods on the cleaned transformed geochemical dataset. The PCA method identified five principal components (PCs), from which PC1 including Cu, Au, and Mo, are specified as the mineralization factor (MF). The GMPI approach can improve the multivariate geochemical signature in geochemical mapping. Hence, the GMPI values of the samples were calculated based on the score values of MF (Cu, Au, Mo). The results convey that the large values of GMPI (MF) (Cu, Au, Mo) strongly correlate with the quartz diorite porphyry rocks and potassic alteration zones. The GMPI (MF (Cu, Au, Mo)) index was modeled using the Concentration-Number (C-N) fractal method. The C-N fractal model identified four geochemical populations based on the different fractal dimensions. The geochemical anomaly map of GMPI (MF) (Cu, Au, Mo) was delineated using these classified populations. The obtained promising areas were validated adequately by more detailed exploration works and deep drilled boreholes as well. The Cu-Au mineralization potential parts are appropriately mapped by this hybrid method. The results obtained demonstrate that this scenario can be adequately used for geochemical mapping on local scales.
R. Satari; A. Akbari Dehkharghani; K. Ahangari
Abstract
Within the last few decades, copper has been identified as one of the most applicable metals by many researchers. These researchers have also been enthusiastic to predict the price of this valuable metal. These days, the available technical analysis methods have been highly applied in the financial markets. ...
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Within the last few decades, copper has been identified as one of the most applicable metals by many researchers. These researchers have also been enthusiastic to predict the price of this valuable metal. These days, the available technical analysis methods have been highly applied in the financial markets. Moreover, the researchers have used these methods to predict the suitable price trends. In the present work, some technical analysis tools including the Fibonacci series, Elliott waves, and Ichimuko clouds were practiced to scrutinize the price changes and predict the copper price. All copper prices from 2008 to 2016 were considered. Regarding the fractal property of these methods, the relations among prices were obtained within an eight-year time sequence. Since 2016, the copper price has been gradually deviated from its previous trend. Using the wave count and Elliott waves has specified that the wave number 1 and wave number 2 have been completed. Now, the time has come to develop the wave number 3. According to the relations introduced by the Elliott waves and the clouds made by Ichimiku, it was determined that the copper price would be almost $16000 per ton in 2022.
Ataallah Bahrami; Reza Hassanpour Kashani; Mirsaleh Mirmohammadi; Fatemeh Kazemi; Ahmad Fathzadeh; Yousef Ghorbani
Abstract
Due to anthropogenic activities of arsenic, its contamination has been widely recognized as one of the most consequential environmental pollutants. This study aims to investigate the possible controlling factors in the amount of arsenic in copper concentrate of the Sungun processing plant – located ...
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Due to anthropogenic activities of arsenic, its contamination has been widely recognized as one of the most consequential environmental pollutants. This study aims to investigate the possible controlling factors in the amount of arsenic in copper concentrate of the Sungun processing plant – located in northwestern Iran. For this purpose, via utilization of process mineralogy approach, an attempt is made to provide a mineralogical-based approach to reduce or remove As from copper concentrate. Chemical analysis of flotation circuit products shows changes of 0.13-1.00% for As in concentrate, and up to 0.003% for tailings. Arsenic is recovered to concentrate in the form of sulfosalt minerals including tennantite and enargite, along with copper sulfides. In order to reduce the arsenic in copper concentrate, flotation tests are performed in Eh values of +300, +200, +100, 0, -100, -200, and -300 mV. Based on the results, a re-flotation step on copper concentrate with a pulp potential range of -300 to +300 mV is conducted as an effective and optimal solution to reduce the amount of As. At a potential of -100 mV, Cu-As minerals (tennantite and enargite) tend to be depressed, and at +300 mV, these minerals tend to float. During the processing circuit, via flotation of particles with a size of -25 μm and adjusting the pulp potential to +300 mV, it is possible to produce two copper concentrates with low arsenic content (< 0.2%) and high arsenic content (> 0.2%). The first concentrate, which is flotation tailings, can be sold in the same way. The second one can be sold after complete removal of arsenic by leaching and then collection of harmful gases.
Rock Mechanics
H. Fattahi; N. Babanouri; Z. Varmaziyari
Abstract
The dynamic response of slopes against earthquake is commonly characterized by the earthquake-induced displacement of slope (EIDS). The EIDS value is a function of several variables such as the material properties, slope geometry, and earthquake acceleration. This work is aimed at the prediction of EIDS ...
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The dynamic response of slopes against earthquake is commonly characterized by the earthquake-induced displacement of slope (EIDS). The EIDS value is a function of several variables such as the material properties, slope geometry, and earthquake acceleration. This work is aimed at the prediction of EIDS using the Monte Carlo simulation method (MCSM). Hence, the parameters height, unit specific weight, cohesion, friction angle, vibration duration, and maximum horizontal acceleration are used to predict the EIDS values. To do this, a multiple non-linear regression relationship is first derived between EIDS and the independent variables. Then MCSM is performed based on the developed regression equation. The results obtained demonstrate that the stochastic approach used is able to successfully reproduce the EIDS values and calculate the confidence intervals. The average of the measured and simulated values for EIDS was 4.34 cm and 4.48 cm, respectively. Eventually, the results of a performed correlation sensitivity analysis revealed that the maximum horizontal acceleration had the greatest impact on EIDS.
A. Hasanzadeh_Sablouei; Seyed M. Moosavirad
Abstract
The electrocoagulation/flotation process is a novel approach in mining industry that is implemented to return Cu metal to the production cycle, which improves copper recovery and reduces waste water. In this research work, the response surface methodology was applied to optimize the factors effective ...
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The electrocoagulation/flotation process is a novel approach in mining industry that is implemented to return Cu metal to the production cycle, which improves copper recovery and reduces waste water. In this research work, the response surface methodology was applied to optimize the factors effective in Cu metal recovery and sludge volume produced from thickener overflow. To this end, the D-optimal experimental design was utilized. The influences of four independent parameters including the electrolysis time, initial pH, current density, and electrodes type were studied to investigate the initial Cu grade percentage (28%) and sludge volume produced from thickener overflow. All these parameters were found to have important effects on the Cu metal recovery and the sludge volume produced. The linear and quadratic models were utilized for the Cu grade and sludge volume, respectively. The importance of the independent variables and the interaction between them was assessed by ANOVA. The optimum operating conditions with 27.22% Cu grade were taken to be: electrolysis time: 6.5 min, initial pH: 6.7, current density: 50.2 A/m2, and electrode type: Fe-Al. Similarly, for the produced sludge volume of 861 cm3, the following conditions were found: electrolysis time: 15 min, initial pH: 4.1, current density: 48.7, and electrode type: Fe-Al. The outcomes underscored a practical viewpoint of electrocoagulation, known as an acceptable method for Cu recovery from mine industrials, especially in mineral processing plants.
Rock Mechanics
Ehsan Taheri; Reza Mohammadpour; Mohammad Hossein Mokhtarzadeh
Abstract
In recent years, the demand for new trenchless methods has dramatically risen. Pipe jacking is a trenchless method widely used in recent years. Ground deformation is one of the significant parameters that may lead to unrepairable harm to facilities and even people. So, ground deformation analysis is ...
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In recent years, the demand for new trenchless methods has dramatically risen. Pipe jacking is a trenchless method widely used in recent years. Ground deformation is one of the significant parameters that may lead to unrepairable harm to facilities and even people. So, ground deformation analysis is necessary for safety and design reasons. The present study analyzes the factors affecting ground deformation during pipe jacking. This is a descriptive-interventional study. Pipe jacking causes soil displacement in three dimensions (3-D). Therefore, 3-D numerical methods were applied for analysis. In this study, numerical simulation was performed using PLAXIS finite element numerical software, taking the case study into account. The effect of each parameter on the ground deformation pattern was studied in three directions; the uplift and their exact position were then analyzed. It should be noted that displacement analyses were performed in two areas: pipe crown and ground surface. Also, the relation of each parameter was estimated with the ground subsidence. Finally, the effect of each different factor and their sensitivity index were determined using sensitivity analysis. The highest subsidence occurs at the end of the shield due to stress relaxation. Considering the results, it was found that the relationship between the internal friction angle and subsidence is linear and direct. The relationship between the elastic modulus and subsidence is also linear but indirect. The results indicate that the most sensitive factor of ground deformation is the diameter, but the least sensitive factor is the face pressure.
Environment
Morteza Niromand; Reza Mikaeil; Mehran Advay; Masoud Zare Naghadehi
Abstract
Slope instability can occur due to external loads such as earthquakes, explosions, and pore pressures. In addition, under natural conditions, slope instability can be caused by factors such as the erosion of some parts of the slope due to water or wind currents and the gradual rise of groundwater levels. ...
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Slope instability can occur due to external loads such as earthquakes, explosions, and pore pressures. In addition, under natural conditions, slope instability can be caused by factors such as the erosion of some parts of the slope due to water or wind currents and the gradual rise of groundwater levels. Another factor leading to slope instability is human activities involving various types of loading and unloading on the slope. The instability of slopes may be associated with limited or large displacements, which either can cause problems or damage structures on the slope. Therefore, this phenomenon needs due care at all slope design and implementation stages. In general, slope stability is influenced by natural factors such as rock type (lithology), tectonic conditions of the area, rock mass joint conditions, and climatic conditions of the area. Furthermore, it is a function of design factors such as dip, height, explosive pattern, and explosion method. The present study offers a multi-factorial fuzzy classification system using the multi-criteria fuzzy approach to evaluate the slope stability. The evaluation is performed in five classes, namely “high stability”, “stable”, “relatively stable”, “unstable”, and “highly unstable”. Next, the viability of 28 slopes of 8 large open-pit mines in different parts of the world was evaluated. According to the fuzzy classification results, 4 and 6 slopes were evaluated in relatively stable and unstable conditions, respectively, with the other slopes classified as stable class. Afterward, the developed fuzzy classification system was assessed based on the actual behavior of the slopes. The results revealed a general large and local failure in most slopes in unstable and relatively stable conditions. Hence, a non-linear multi-factorial fuzzy classification system with good reliability can be used to evaluate the stability of the slopes.
L. Daneshvar Saein
Abstract
The purpose for this research is to define the gold mineralization potentials by the concentration-number fractal and staged factor analysis modeling based on rock samples at the Bardaskan area (NE Iran). Two main gold mineralization types are epithermal and disseminated systems in this district. First, ...
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The purpose for this research is to define the gold mineralization potentials by the concentration-number fractal and staged factor analysis modeling based on rock samples at the Bardaskan area (NE Iran). Two main gold mineralization types are epithermal and disseminated systems in this district. First, the staged factor analysis is carried out at four stages. The stepwise factor analysis was applied in three stages to remove noise elements. Moreover, staged factor analysis was applied in the fourth step based on metallic elements including Au, Ag, Cu, As, Fe, Mo, Bi, La, S, Zn, and Cd were grouped. These elements are grouped at four factors, and related factors for gold mineralization are F1-4 (first factor in the fourth stage) which is consisting of As, Mo, S and Fe and F3-4 (third factor in the fourth stage) includes Au and Ag. The concentration-number log–log plots for factor scores of F1-4 and F3-4 were generated, and their threshold values were calculated to create the factor score’s geochemical maps. Based on these results, the gold mineralization potentials are positioned in the NE, northern and SE sections of the district, which indicate a correlation among alteration zones, including chloritization, sericitization, and silicification alteration zones and faults and fault’s intersections. Main Au mineralization occurred in silicified-sulfidic veins/veinlets in NE and northern portions of the region. However, high grade F3-4 anomalies are located in intersection of faults and neighboring fault zones especially at the northern part of this district. Moreover, Samples with Au≥ 100 ppb were situated in major anomalous parts of F3-4 (Au-Ag) and marginal parts of the F1-4, which include pathfinder of gold mineralization.
