N Mathiyazhagan; Natarajan D
Abstract
An ex-situ experiment to assess the metal extractive potential of fourteen agriculture plants (Vigna unguiculata, Gossypium hirsutum, Jatropha curcas, etc.) was conducted on Magnesite mines which had above permissible levels of Cadmium and Lead. There was no much difference in the total chlorophyll a ...
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An ex-situ experiment to assess the metal extractive potential of fourteen agriculture plants (Vigna unguiculata, Gossypium hirsutum, Jatropha curcas, etc.) was conducted on Magnesite mines which had above permissible levels of Cadmium and Lead. There was no much difference in the total chlorophyll a and b, carbohydrate and protein contents in the plants grown in the mining soil and adjacent control area (farm soil). While considering the phytoextractive potential, among the 14 plants studied, V. ungiculata, O. sativa, S. bicolour, S. indium, R. communis, M. uniflorum, G. hirsutum and J. curcas contained considerable amount of heavy metals Cd and Pb other test plants. The experiment confirms that these plants have potential to accumulate the toxic trace elements from soil especially mining waste or dump. The subsequent confirmation studies on their metal tolerant index, metal transfer factor, translocation factor and MREI index values auger their potential phyto-extractive properties. The present study will pave way for in depth related studies in future.
Environment
N. Zandy Ilghani; F. Ghadimi; M. Ghomi
Abstract
The Haft-Savaran Pb-Zn mineralization zone with the lower Jurassic age is located in the southern basin of Arak and Malayer-Isfahan metallogenic belt of Iran. Based upon the geological map of the Haft-Savaran area, the sandstone and shale of lower Jurassic are the main rocks of Pb-Zn deposit. In this ...
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The Haft-Savaran Pb-Zn mineralization zone with the lower Jurassic age is located in the southern basin of Arak and Malayer-Isfahan metallogenic belt of Iran. Based upon the geological map of the Haft-Savaran area, the sandstone and shale of lower Jurassic are the main rocks of Pb-Zn deposit. In this area, 170samples were taken from 33 boreholes, and44 elements were measured by the ICP-MS method. Adaptation of the alteration index and Pb–Zn mineralization was investigated in this work. The model was created based on the Sericitic, Spitz-Darling, Alkali, Hashimoto, and Silicification Indices in all boreholes. This work showed that the Sericite, Hashimoto, Spitz-Darling, and Silicification indices increased around mineralization, and the alkali index decreased around it. Development of the alteration indices indicates that direction of the ore-bearing solution is NE-SW, and that this trend is consistent with the faults in the area. Based upon the 3D models and other data interpretations, Pb–Zn and elements such as Fe, Mn, Cr, and Ni have deposited within the alteration zones.
H. A. Mirzaei; M. Noaparast; H. Abdollahi
Abstract
The precipitation of aluminum hydroxide from a supersaturated sodium aluminate solution is known as an essential production step in the Bayer process. In this work, the real precipitation process in the Iran Alumina Plant was modeled by the historical data with the help of Design Expert. According to ...
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The precipitation of aluminum hydroxide from a supersaturated sodium aluminate solution is known as an essential production step in the Bayer process. In this work, the real precipitation process in the Iran Alumina Plant was modeled by the historical data with the help of Design Expert. According to the results obtained, the recovery is significantly improved with decrease in the super-saturation factor (α) of the solution. However, this modification was found to be the most difficult change due to the operational problems. The results obtained indicated the significant impact of the seed size on the product size. The negligible effects of the other parameters involved on controlling the amount of fine grains (< 44 µm) and coarse grains (> 150 µm) in the product showed the significance of reactivating the classification and agglomeration sections. Ultimately, it was found that the recovery process could be enhanced from 46.32% to 47.86% at a constant α by increasing the seed concentration to 400 g/L, increasing the retention time by adding two precipitation tanks and reducing the temperature of the last precipitation tank by 2 ºC (by reducing the temperature of the inlet suspension), while preserving the quality of the product.
Mineral Processing
D. Ghoddocy Nejad; M. Taghizadeh; A. R. Khanchi
Abstract
In this work, thealkaline roasting and sulfuric acid leaching processes were employed to extract vanadium from the magnetite ore of Saghand mine in central Iran. The response surface methodology based on the central composite design model was applied to optimize the parameters involved in the processes. ...
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In this work, thealkaline roasting and sulfuric acid leaching processes were employed to extract vanadium from the magnetite ore of Saghand mine in central Iran. The response surface methodology based on the central composite design model was applied to optimize the parameters involved in the processes. The studied roasting parameters were temperature (900-1100 °C), sodium carbonate percentage (30-50 wt%), and time (1-3 h). In addition, the studied leaching factors included temperature (70-90 °C), liquid-to-solid ratio (L/S) (5-20 mL/g), sulfuric acid concentration (2-6 M), and time (3-6 h). Under the optimal conditions, the values for temperature, time, and sodium carbonate amounted to 1010 °C, 2.1 h, and 41 wt%, respectively, for the roasting process, while the values for temperature, L/S, sulfuric acid concentration, and time for the leaching process were estimated to be 85 °C, 12.4 mL/g, 4.25 M, and 4.7 h, respectively. Under these conditions, about 83.8 ± 0.9% of vanadium was leached from the magnetite ore.
H. Shahriari; M. Honarmand; S. Mirzaei; A. Saffari
Abstract
This research work aims to discuss the methodology of using the drone-based data in the initial steps of the exploration program for the dimension stone deposits. A high-resolution imaging is performed by a low-cost commercial drone at the Emperador marble quarry, Kerman province, Iran. A ground resolution ...
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This research work aims to discuss the methodology of using the drone-based data in the initial steps of the exploration program for the dimension stone deposits. A high-resolution imaging is performed by a low-cost commercial drone at the Emperador marble quarry, Kerman province, Iran. A ground resolution of 3 cm/pix is achieved by imaging at an altitude of 70 m in order to ensure the precise lithological and structural mapping. An accuracy of less than 5 cm is promised for the 3D photogrammetric products. Hence, the flight is performed with an 80% front and a 70% lateral image overlap. Furthermore, 18 ground control points (GCPs) are used in order to meet the required accuracy. Photogrammetric processing is done by the Agisoft PhotoScan software. The geology map is prepared through the visual geo-interpretation of the orthophoto image. The faults and fractures are delineated using the high-resolution orthophoto and hill-shade model in the ArcGIS software. Accordingly, the density map of fractures is produced, and the deposit is divided into five structural zones. The 3D deposit model with an accuracy of 2.8 cm is reconstructed based on the digital elevation model (DEM). A primary block model is generated using the 3D deposit model in the Datamine software in order to determine the resource for each structural zone. Finally, considering the amount of resource and situation of fractures, the priority of exploration for developing activities and appropriate methods is defined for each structural zone. The research work results have convinced us to include drone-based imagery in the initial steps of dimension stone exploration to consume the time and cost of the operation.
F. Sadough Abbasian; B. Rezai; A. R. Azadmehr; H. Hamidian
Abstract
In this work, two clay-based composites are prepared for the adsorptive removal of the chloride ions from aqueous solutions. These composites are characterized through Fourier transform-infrared spectroscopy, scanning electron microscopy, X-ray fluorescence spectroscopy, and X-ray diffraction analysis. ...
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In this work, two clay-based composites are prepared for the adsorptive removal of the chloride ions from aqueous solutions. These composites are characterized through Fourier transform-infrared spectroscopy, scanning electron microscopy, X-ray fluorescence spectroscopy, and X-ray diffraction analysis. The effects of different parameters such as the contact time, amount of adsorbent, chloride concentration, temperature, and pH are studied by batch experiments. Also the isotherm, kinetic, and thermodynamic of the adsorptive removal of the chloride ions from these two composites are investigated. According to the results obtained, the adsorptive removal of chloride ions is initially rapid, and the equilibrium time is reached after 30 min. The optimal pH value is 7.0 for a better adsorption, and the maximum capacity can be achieved, which is 60.2 mg/g with 1000 mg/L of the initial chloride concentration. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich adsorption models are applied to describe the equilibrium isotherms at different chloride concentrations. According to the equilibrium isotherms and the correlation coefficients (R2CDC: 0.9424, R2LDC: 0.996), the process can be described by the Langmuir model, and exhibits the highest removal rate of 97.24% (24.31 mg/g) with 250 mg/L of the initial chloride concentration. The pseudo-first-order and pseudo-second-order, intra-particle diffusion, and mass transfer kinetics models are used to identify the mechanism of the adsorptive removal of the chloride ions. The pseudo-second order model due the correlation coefficients (R2CDC: 0.9217-0.9852, R2LDC: 0.9227-0.9926) can be fitted to the kinetic calculations, and it is applicable for the adsorptive removal of chloride ions by the adsorbents. The thermodynamic calculations show that in a low chloride concentration, the sorption is spontaneous, associative, and endothermic; and in a high concentration, it is unspontaneous, dissociative, and endothermic. The calculated value of free energy (E) for adsorption onto the adsorbents suggests that the reaction rate controls the adsorptive removal of the chloride process rather than diffusion. It can be concluded that these two composites can be used as effective and applicable adsorbents for the adsorptive removal of chloride ions.
Sajjad Jannesar Malakooti; Hadi Abdollahi; Ziaeddin Pourkarimi; Behrouz Karimi Shahraki; Mehdi Rahimi; Mohammadreza Shahbazi; Ahmad Rahmanian kooshkaki
Abstract
Parvadeh IV and East Parvadeh mines are two main coal-producing zones within the Tabas coalfield, east of Iran. Since studies have shown that C1 and B2 are the most important working seams in the Parvadeh IV and east Parvadeh areas, this research work focuses on these two coal seams. Syngenetic pyrite ...
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Parvadeh IV and East Parvadeh mines are two main coal-producing zones within the Tabas coalfield, east of Iran. Since studies have shown that C1 and B2 are the most important working seams in the Parvadeh IV and east Parvadeh areas, this research work focuses on these two coal seams. Syngenetic pyrite is available as framboids related to macerals. Decreasing the sulfur content is especially hard when the pyrite particles are fine-grained, finely disseminated, and intergrown with the coal maceral structure. The sulfur content measured in C1 and B2 seams varies from 0.98% to 5.57% and from 0.73% to 5.25%, respectively, with an average of 2.39% and 2.5%. We use a method to predict how coal desulfurized the C1and B2seams of Parvadeh IV and C1 seams of east Parvadeh mines in the Tabas coalfield. The results have given new proofs for the presence of pyrite and clay minerals within the coalfield zone, and to identify a method to predict coal desulfurization with conventional processing and cost-effective methods. The coal preparation strategy in MEMRADCO, Parvadeh, and Ehyasepahan coal-cleaning plants not as it expels mineral matter and pyrite but too reduces the content of most inorganic components.
Rock Mechanics
M. Noroozi; R. Rafiee; M. Najafi
Abstract
Various structural discontinuities, which form a discrete fracture network, play a significant role in the failure conditions and stability of the rock masses around underground excavations. Several continuum numerical methods have been used to study the stability of underground excavations in jointed ...
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Various structural discontinuities, which form a discrete fracture network, play a significant role in the failure conditions and stability of the rock masses around underground excavations. Several continuum numerical methods have been used to study the stability of underground excavations in jointed rock masses but only few of them can take into account the influence of the pre-existing natural fractures. In this work, the pre-existing fractures are explicitly modeled as a Discrete Fracture Network (DFN) model, which is fully coupled with the FEM modeling for stability analysis of support systems in a diversion tunnel at the Rudbar Lorestan dam site. Hence, at first, using the surveyed data in the diversion tunnel and an estimation of the suitable probability distribution function on geometric characteristics of the existing joint sets in this region, the 3D DFN model was simulated using the stochastic discrete fracture networks generator program, DFN-FRAC3D. In the second step, a coupled 2D Finite Element Method and the prepared stochastic model were used for analysis of existent (based on technical reports) recommended support systems. The objective here is to grasp the role of the fracture networks on the results of the tunnel stability analysis using FEM modeling and also to compare the results with those obtained through stability analysis without considering the effect of fractures.
Rock Mechanics
H. Fattahi; N. Zandy Ilghani
Abstract
Horizontal directional drilling is usually used in drilling engineering. In a variety of conditions, it is necessary to predict the torque required for performing the drilling operation. Nevertheless, there is presently not a convenient method available to accomplish this task. In order to overcome this ...
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Horizontal directional drilling is usually used in drilling engineering. In a variety of conditions, it is necessary to predict the torque required for performing the drilling operation. Nevertheless, there is presently not a convenient method available to accomplish this task. In order to overcome this difficulty, the current work aims at predicting the required rotational torque (RT) to operate horizontal directional drilling on the 7 effective parameters including the length of drill string in the borehole (L), axial force on the cutter/bit (P), total angular change of the borehole (KL), radius for the ith reaming operation (Di), rotational speed (rotation per minute) of the bit (N), mud flow rate (W), and mud viscosity (V). In this paper, we propose an approach based on the model selection criteria such as various statistical performance indices mean squared error (MSE), variance account for (VAF), root mean squared error (RMSE), squared correlation coefficient (R2), and mean absolute percentage error (MAPE) to select the most appropriate model among a set of 20 candidate ones to estimate RT, given a set of observed data. Once the most appropriate model is selected, a Bayesian framework is employed to develop the predictive distributions of RT, and to update them with new project-specific data that significantly reduce the associated predictive uncertainty. Overall, the results obtained indicate that the proposed RT model possesses a satisfactory predictive performance.
M. R. Shahverdiloo; Sh. Zare
Abstract
Hydraulic fracturing (HF) and hydraulic testing of pre-existing fractures (HTPF) are efficient hydraulic methods in order to determine the in-situ stress of rock mass. Generally, the minimum (Sh) and maximum (SH) horizontal principal stresses are measured by hydraulic methods; ...
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Hydraulic fracturing (HF) and hydraulic testing of pre-existing fractures (HTPF) are efficient hydraulic methods in order to determine the in-situ stress of rock mass. Generally, the minimum (Sh) and maximum (SH) horizontal principal stresses are measured by hydraulic methods; the vertical stress (SV) is calculated by the weight of the overburden layers. In this work, 37 HF and HTPF tests are conducted in a meta-sandstone, which has about 10% inter-layer phyllite. The artesian circumstance, considerable gap between the drilling and hydraulic tests in the long borehole, no underground access tunnel to rock cavern at the early stages of projects, and a simplified hypothesis theory of HF are the main challenges and limitations of the HF/HTPF measurements. Due to the instability in the long borehole, the drill rig type and borehole length are revised; also TV logger is added to the process of selection of the test’s deep. The HF/HTPF data is sequentially analyzed by the classic and inversion methods in order to achieve an optimum number of hydraulic tests. Besides, The SH magnitude in the inversion method is lower than the classic method; the relevant geological data and the faulting plan analysis lead to validate the SH and Sh magnitudes and the azimuths obtained by the classic method. The measured SH and Sh magnitudes are 7-17 MPa and 4-11 MPa, respectively; the calculated vertical stress magnitude is 6-14 MPa at the test locations. Indeed, the stress state is (SH > SV > Sh), and SH azimuth range is 56-93 degrees.
T. Ramezanalizadeh; M. Monjezi; A. R. Sayadi; A. Mousavinogholi
Abstract
Waste rock dumping is very important in the production planning of open-pit mines. This subject is more crucial when there is a potential of acid-forming (PAF) by waste rocks. In such a type of mines, to protect the environment, the PAF materials should be encapsulated by non-harmful rocks. Therefore, ...
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Waste rock dumping is very important in the production planning of open-pit mines. This subject is more crucial when there is a potential of acid-forming (PAF) by waste rocks. In such a type of mines, to protect the environment, the PAF materials should be encapsulated by non-harmful rocks. Therefore, block sequencing of the mined materials should be in such a way that both the environmental and economic considerations are considered. If non-acid forming (NAF) rocks are not mined in a proper time, then a stockpile is required for the NAF materials, which later on would be re-handled for encapsulation of PAF rocks. In the available models, the focus is on either block sequencing or waste dumping strategy. In this work, an attempt has been made to develop an integrated mathematical model for simultaneous optimization of block sequencing and waste rock dumping. The developed model not only maximizes the net present value (NPV) but also decreases the destructive environmental effects of inappropriate waste dumping. The proposed model, which is solved by a CPLEX engine, is applied to two different iron deposits. Also the performance of the proposed model is cross-checked by applying the available (traditional) models in a two-step manner. According to the results obtained, it can be considered that utilizing the developed model, because of extensive re-handling cost reduction, the NPV improvement is significant, especially when the overall stripping ratio is higher (deposit case A).
B. Alipenhani; A. Majdi; H. Bakhshandeh Amnieh
Abstract
The present work aims at implementing Response Surface Methodology (RSM) in order to generate a statistical model for Minimum Required Caving Span (MRCS) and estimate both the individual and mutual effects of the rock mass parameters on rock mass cavability. The adequate required data is obtained from ...
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The present work aims at implementing Response Surface Methodology (RSM) in order to generate a statistical model for Minimum Required Caving Span (MRCS) and estimate both the individual and mutual effects of the rock mass parameters on rock mass cavability. The adequate required data is obtained from the result of numerical modeling. In this work, various arrays of numerical simulations (480 models) are carried out using the UDEC software in order to study the rock mass cavability thoroughly. The effect of each individual parameter and their mutual effect on MRCS are investigated by means of ANOVA. ANOVA indicates that all the chosen parameters (depth, dip of the joint, number of joints, angle of friction of the joint surface, and joint spacing) highly affect MRCS. In other words, the results of ANOVA are in high agreement with the results of the conventional sensitivity analysis. Moreover, a combination of joint spacing and joint inclination has the highest mutual effect on MRCS, and a combination of undercut depth and joint spacing has the lowest effect on MRCS.
Exploitation
P. Afzal
Abstract
Finding a proper estimation method for ore resources/reserves is important in mining engineering. The aim of this work is to compare the Ordinary Kriging (OK) and Advanced Inverse Distance Squared (AIDS) methods based on the correlation between the raw and estimated data in the East-Parvadeh coal deposit, ...
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Finding a proper estimation method for ore resources/reserves is important in mining engineering. The aim of this work is to compare the Ordinary Kriging (OK) and Advanced Inverse Distance Squared (AIDS) methods based on the correlation between the raw and estimated data in the East-Parvadeh coal deposit, central Iran. The variograms and anisotropic ellipsoids are calculated to estimate the ash and sulfur distributions by the IDS and OK methods. The results obtained by these techniques show that their correlation coefficients are similar for the raw and estimated data. However, the statistical parameters obtained by the AIDS method are better based on the ash and sulfur means, although the variance of these variables is lower according to the OK method. The results obtained indicate that the AIDS method yields more reliable results than the OK method.
Exploitation
H. Shahsavani
Abstract
Recently, the non-destructive methods have become of interest to the scientists in various fields. One of these method is Ground Penetration Radar (GPR), which can provide a valuable information from underground structures in a friendly environment and cost-effective way. To increase the signal-to-noise ...
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Recently, the non-destructive methods have become of interest to the scientists in various fields. One of these method is Ground Penetration Radar (GPR), which can provide a valuable information from underground structures in a friendly environment and cost-effective way. To increase the signal-to-noise (S/N) ratio of the GPR data, multi-fold acquisition is performed, and the Common-Mid-Points (CMPs) are acquired. Compared to the traditional CMP method, which is applied to a CMP, the Common-Reflection-Surface (CRS) method is introduced for seismic data processing considering the neighboring CMPs. In addition, instead of a point on the reflector, CRS assumes that the reflector is part of a circle. With these two characteristics, CRS produces a stack section with a high S/N ratio. The Common-Diffraction-Surface (CDS) method, which is a simplified version of CRS, enhances the diffractors related to the underground anomalies like pipeline, flume, and caves. We apply the CDS stack method on a multi-fold GPR data and compare it to the CRS results. These results show that the CDS method can provide a high S/N ratio stack section compared to the traditional CMP method.
M. Jahani Chegeni; S. Kolahi
Abstract
The number of lifters in the liner of ball mills and the mill rotation speed are among the most significant factors affecting the behavior of grinding charge (balls) and their motion trajectory, and consequently, the comminution mechanism in these mills. In this research, in order to find a suitable ...
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The number of lifters in the liner of ball mills and the mill rotation speed are among the most significant factors affecting the behavior of grinding charge (balls) and their motion trajectory, and consequently, the comminution mechanism in these mills. In this research, in order to find a suitable range for the number of lifters in the liner of ball mills, the DEM method is utilized. Initially, a pilot-scale ball mill with dimensions of 2.0 m × 1.11 m without any lifter is simulated. Afterwards, by adding, respectively, 1, 2, 4, 8, 16, 20, 26, 30, and 32 cuboid lifter(s) with dimensions of 2 m × 5 cm × 5 cm, nine other separate simulations are performed. The influences of the number of cuboid lifters on the two new factors introduced here, namely ‘head height’ (HH) and ‘impact zone length’ (IZL) at various mill speeds, that is, 70% and 80% of its critical speed (CS) are investigated. The results indicate that in order to find a suitable range for the number of lifters in the liner of ball mills, it is necessary to consider these two parameters simultaneously as the criteria for selecting the appropriate range, That is, liners that simultaneously produce both a higher HH and a greater IZL are more suitable for use in the industry. The results also demonstrate that the suitable range for the number of cuboid lifters in the liner of ball mills is between 16 and 32, which field research on the ball mills of three different plants in the industry confirms the accuracy of the results obtained in this research. Unlike the previous research works, it has now been shown that the number of ball mill lifters does not only depend on the diameter of the mill but also depends on the width, height, angle of the lifter, and generally on the type of lifter.
D. Mohammadi; R. Mikaeil; J. Abdollahei Sharif
Abstract
The blasting method is one of the most important operations in most open-pit mines that has a priority over the other mechanical excavation methods due to its cost-effectiveness and flexibility in operation. However, the blasting operation, especially in surface mines, imposes some environmental problems ...
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The blasting method is one of the most important operations in most open-pit mines that has a priority over the other mechanical excavation methods due to its cost-effectiveness and flexibility in operation. However, the blasting operation, especially in surface mines, imposes some environmental problems including the ground vibration as one of the most important ones. In this work, an evaluation system is provided to study and select the best blasting pattern in order to reduce the ground vibration as one of the hazards in using the blasting method. In this work, 45 blasting patterns used for the Sungun copper mine are studied and evaluated to help determine the most suitable and optimum blasting pattern for reducing the ground vibration. Additionally, due to the lack of certainty in the nature of ground and the analyses relating to this drilling system, in the first step, a combination of the imperialist competitive algorithm and k-means algorithm is used for clustering the measured data. In the second step, one of the multi-criteria decision-making methods, namely TOPSIS (Technique for Order Performance by Similarity to Ideal Solution), is used for the final ranking. Finally, after evaluating and ranking the studied patterns, the blasting pattern No. 27 is selected. This pattern is used with the properties including a hole diameter of 16.5 cm, number of holes of 13, spacing of 4 m, burden of 3 m, and ammonium nitrate fuel oil of 1100 Kg as the most appropriate blasting pattern leading to the minimum ground vibration and reduction of damages to the environment and structures constructed around the mine.
S. Ghasemi; S. Mohammadnejad; M. R. Khalesi
Abstract
The adsorption of gold and copper cyanide complexes on the activated carbon is investigated using the Density Functional Theory (DFT). In order to represent the activated carbon, two fullerene-like model (presenting structural defect sites) and a simple graphene layer containing different functional ...
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The adsorption of gold and copper cyanide complexes on the activated carbon is investigated using the Density Functional Theory (DFT). In order to represent the activated carbon, two fullerene-like model (presenting structural defect sites) and a simple graphene layer containing different functional groups (presenting chemical active sites) are employed. The structural defect sites show a much lower adsorption tendency toward all the cyano complexes comparing to the chemical active sites. The interaction energy for all of the complexes with structural defect sites (concave) is very low. However, the graphene layer with unsaturated active sites displays the highest level of interaction almost for all the complexes except Cu(CN)4-3. The effect of oxygen functional groups on the graphite edges shows a crucial role in the selectivity of gold adsorption over copper complexes. It has increased adsorption energy for Cu(CN)2- in the presence of OH and COOH, and has decreased adsorption energy for Au(CN)2- by OH and increased by COOH. The study results elucidate the lower selectivity for adsorption of gold over copper cyanides by high oxygen content activated carbon. The energy levels of the HOMO and LUMO orbitals show adsorption of unpaired cyanide anions on the activated carbon surface occurs by electron transfer from the complex to the adsorbent and adsorption onto the activated carbon edges by transferring electrons from the absorbent to the complex. The result has clearly demonstrated that the functional groups increase the adsorption tendency for both the gold (only COOH) and copper complexes (OH and COOH) but deteriorate the selectivity of gold over copper cyanides.
Mineral Processing
R. Ahmadi; E. Ravanasa; Y. Mirzapour
Abstract
In this work, adsorption of the potassium amyl xanthate collector on the pure chalcopyrite surface was studied by applying atomic force microscopy (AFM). The adsorption experiments were carried out at different concentrations of the collector and at diverse pH values in the presence or absence of exterior ...
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In this work, adsorption of the potassium amyl xanthate collector on the pure chalcopyrite surface was studied by applying atomic force microscopy (AFM). The adsorption experiments were carried out at different concentrations of the collector and at diverse pH values in the presence or absence of exterior ions. The changes occurring in the surface morphology of chalcopyrite due to the collector adsorption were evaluated by measuring the contact angle of the collector and its surface coating. According to the 3D images obtained by AFM, an increase in the pH value from 7.5 to 9.5 at two concentrations of 25*10-3 and 50*10-3 g/ton of the collector would increase the number of particles adsorbed on the surface, improve the adsorption morphology, and reduce the contact angle. Moreover, at a constant pH value, increasing the collector would result in the proliferation of contact angles as well as a relative increase in the number of particles. By comparing the morphological surface changes in the tap and distilled water samples, applying tap water, owing to the presence of Cu2+ ions and activation of the surface through the production of CuS, the quality and quantity of adsorption would be increased. The use of tap water not only can account for an appropriate coating by the collector but also causes to reduce the consumption of collector for at least 50%.
Mineral Processing
H. Jafari; H. Abdollahi; M. Gharabaghi; A.A. Balesini
Abstract
In this research work, solvent extraction and stripping of zinc ions from a Zn-Mn-Cd-bearing solution was investigated using D2EHPA as the extractant in a chloride medium. The efficiency of the extraction and stripping stages was evaluated separately, and different parameters such as the pH, extractant ...
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In this research work, solvent extraction and stripping of zinc ions from a Zn-Mn-Cd-bearing solution was investigated using D2EHPA as the extractant in a chloride medium. The efficiency of the extraction and stripping stages was evaluated separately, and different parameters such as the pH, extractant concentration, reaction temperature, and contact time were studied. Based on the results obtained, 97% of zinc, 14% of manganese, and 3% of cadmium were extracted at pH = 2.5, 10% (v/v) of D2EHPA, and 40 °C from the solution containing 5 g L-1 of each metal ion. The stripping isotherms of zinc, manganese, and cadmium at different pH values showed that manganese and zinc were stripped at two different pH values. Thus more than 70% of manganese and more than 90% of zinc were stripped at pH = 2.5 and pH = 0.5, respectively. Kinetic studies indicated that the extraction and stripping of zinc in the first 0.5-1 minute was high. The McCabe–Thiele diagrams showed that two stages of extraction and two stages of stripping in the continuous counter-current flow condition were adequate to separate zinc from Mn and Cd. The dominant Zn species extracted by D2EHPA was ZnCl+, and the values for the thermodynamic parameters ΔHo, ΔSo, and ΔGo were 25.65 kJ mol−1, 79.20 J K−1 mol−1, and 0.86 kJ mol−1, respectively, which showed that the reaction was endothermic at equilibrium.
G. Jozanikohan; M. Nosrati Abarghooei; H. Sedighi
Abstract
The most extensive Iranian coal-bearing basin is located in an area of 30000 km2, situated approximately 75 km from the Tabas county, south Khorasan Province, Iran. In this work, the Tabas coal ash is studied and investigated for the purpose of determination of the rare earth elements (REE) content, ...
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The most extensive Iranian coal-bearing basin is located in an area of 30000 km2, situated approximately 75 km from the Tabas county, south Khorasan Province, Iran. In this work, the Tabas coal ash is studied and investigated for the purpose of determination of the rare earth elements (REE) content, and the identification of the distribution patterns of trace elements. The elemental and phase analysis experiments were conducted using the X-ray diffraction (XRD), inductively-coupled plasma spectroscopy (ICP-MS), wet chemical analysis, and field emission scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (FE-SEM/EDS) techniques. The XRD results showed that the phases in the Tabas coal ash were quartz, clay minerals, alkali feldspar, magnetite, and pyrite in order of abundance. The elemental analysis showed that the major elements were Si, Al, K, Fe, Mg, S, and Na, which was in good accordance with the chemical composition of the recognized minerals by the XRD method. The concentration of REEs was varied from 0.10 ppm (for Tm) to 68.48 ppm (for Ce), with an arithmetic mean of 14.19 ppm. The abundance of 16 REE elements was or even below the average of the earth crust abundances. Only one rare earth element (Samarium) was about 4.4 and 2.2 times more abundant than in the earth crust and in the world coking coal ashes. In order to further assess the occurrence states of REEs in each of detected mineral, the Fe-SEM/EDX method was used. The SEM/EDS analysis showed that REEs were mainly concentrated in the clay minerals.
B. Shokouh Saljoughi; A. Hezarkhani
Abstract
In this paper, we aim to achieve two specific objectives. The first one is to examine the applicability of wavelet neural network (WNN) technique in ore grade estimation, which is based on integration between wavelet theory and Artificial Neural Network (ANN). Different wavelets are applied as activation ...
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In this paper, we aim to achieve two specific objectives. The first one is to examine the applicability of wavelet neural network (WNN) technique in ore grade estimation, which is based on integration between wavelet theory and Artificial Neural Network (ANN). Different wavelets are applied as activation functions to estimate Cu grade of borehole data in the hypogene zone of porphyry ore deposit, Shahr-e-Babak district, SE Iran. WNN parameters such as dilation and translation are fixed and only the weights of the network are optimized during its learning process. The efficacy of this type of network in function learning and estimation is compared with Ordinary Kriging (OK). Secondly, we aim to delineate the potassic and phyllic alteration regions in the hypogene zone of Cu porphyry deposit based on the estimation obtained of WNN and OK methods, and utilize Concentration–Volume (C–V) fractal model. In this regard, at first C–V log–log plots are generated based on the results of OK and WNN. The plots then are used to determine the Cu threshold values of the alteration zones. To investigate the correlation between geological model and C-V fractal results, the log ratio matrix is applied. The results showed that, Cu values less than 1.1% from WNN have more overlapped voxels with phyllic alteration zone by overall accuracy (OA) of 0.74. Spatial correlation between the potassic alteration zones resulted from 3D geological modeling and high concentration zones in C-V fractal model showed that the alteration zone has Cu values between 1.1% and 2.2% with OA of 0.72 and finally have an appropriate overlap with Cu values greater than 2.2% with OA of 0.7. Generally, the results showed that the WNN (Morlet activation function) with OA greater than OK can be can be a suitable and robust tool for quantitative modeling of alteration zones, instead of qualitative methods.
Vahab Sarfarazi; Hadi Haeri; Fereshteh Bagheri; Erfan Zarrin ghalam; Mohammad Fatehi Marji
Abstract
The tensile strengths of geomaterials such as rocks, ceramics, concretes, gypsum, and mortars are obtained based on the direct and indirect tensile strength tests. In this research work, the Brazilian tensile strength tests are used to study the effects of length and inclination angle of T-shaped non-persistent ...
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The tensile strengths of geomaterials such as rocks, ceramics, concretes, gypsum, and mortars are obtained based on the direct and indirect tensile strength tests. In this research work, the Brazilian tensile strength tests are used to study the effects of length and inclination angle of T-shaped non-persistent joints on the mechanical and tensile behaviors of the geomaterial specimens prepared from concrete. These specimens have a thickness of 40 mm and a diameter of 100 mm, and are prepared in the laboratory. Two T-shaped non-persistent joints are made within each Brazilian disc specimen. The Brazilian disc specimens with T-shaped non-persistent joints are tested experimentally in the laboratory under axial compression. Then these tests are simulated in the two-dimensional particle flow code (PFC2D) considering various notch lengths of 6, 4, 3, 2, and 1 cm. However, different notch inclination angles of 0, 30, 60, 90, 120, and 150 degrees are also considered. In this research work, 12 specimens with different configurations are provided for the experimental tests, and 18 PFC2D models are made for the numerical studies of these tests. The loading rate is 0.016 mm/s. The results obtained from these experiments and their simulated models are compared, and it is concluded that the mechanical behavior and failure process of these geomaterial specimens are mainly governed by the inclination angles and lengths of the T-shape non-persistent joints presented in the samples. The fracture mechanism and failure behavior of the specimens are governed by the discontinuities, and the number of induced cracks when the joint inclination angles and joint lengths are increased. For larger joints when the inclination angle of the T-shaped non-persistent joint is around 60 degrees, the tensile strength is minimum but as it is closed to 90 degrees, the compressive strengths are maximum. However, an increase in the notch length increase the overall tensile strength of the specimens. The strength of samples decreases by increasing the joint length. The strain at the failure point decreases by increasing the joint length. It is also observed that the strength and failure process of the two sets of specimens and the corresponding numerical simulations are consistence.
Mehdi Hosseini; Alireza Dolatshahi; Esmaeel Ramezani
Abstract
This work investigates the effect of adding micro-silica as a pozzolan and a replacement for part of concrete cement when placing concrete in an acidic environment. Two types of ordinary concrete and concrete-containing micro-silica are constructed. The specimens are subjected to 0, 1, 5, and 10 cycles ...
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This work investigates the effect of adding micro-silica as a pozzolan and a replacement for part of concrete cement when placing concrete in an acidic environment. Two types of ordinary concrete and concrete-containing micro-silica are constructed. The specimens are subjected to 0, 1, 5, and 10 cycles for two hours inside two types of acidic water containing sulfuric and nitric acid with pH = 3 and normal water with pH = 7. Mechanical properties including Brazilian tensile strength and uniaxial compressive strength, and physical properties including effective porosity, water absorption, and the longitudinal wave velocity of specimens are determined after the mentioned number of cycles. Thr results show that by decreasing the pH and increasing the number of cycles, the effective porosity and water absorption increase, and the velocity of longitudinal waves, Brazilian tensile strength, and uniaxial compressive strength of concrete decrease. Replacing 10% of micro-silica as a part of concrete cement has boosted the durability of concrete in corrosive conditions containing sulfuric and nitric acid more than ordinary concrete.
Hassan Bakhsandeh Amnieh; Alireza Mohammadi; M Mozdianfard
Abstract
Ground vibrations caused by blasting are undesirable results in the mining industry and can cause serious damage to the nearby buildings and facilities; therefore, controlling such vibrations has an important role in reducing the environmental damaging effects. Controlling vibration caused by blasting ...
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Ground vibrations caused by blasting are undesirable results in the mining industry and can cause serious damage to the nearby buildings and facilities; therefore, controlling such vibrations has an important role in reducing the environmental damaging effects. Controlling vibration caused by blasting can be achieved once peak particle velocity (PPV) is predicted. In this paper, the values of PPV have been predicted and compared using the artificial neural network (ANN), multivariate regression analysis (MVRA) and empirical relations. The necessary data were gathered from 11 blast operations in Sarcheshmeh copper mine, Kerman. The neural network input parameters include distance from blast point, maximum charge weight per delay, spacing, stemming and the number of drill-hole rows in each blasting operation. The network is of the multi-layer perception (MLP) type with 24 sets of training data including 2 hidden layers, 1 output layer with the network architecture of {5-11-12-1}, and Sigmoid tangent and linear transfer functions. To insure the training accuracy, the network was tested by 6 data sets; the determination coefficient and the average relative error were found to be 0.977 and 8.85%, respectively, showing the MLP network’s high capability and precision in estimating the values of the PPV. To predict these values, MVRA and empirical relations were analyzed. The results have revealed that these relations have low capability in estimating the PPV parameter.
Mineral Processing
M. B. Fathi; B. Rezai; E. K. Alamdari; R. D. Alorro
Abstract
The effects of the functional groups and structures of two different resins, weak base/macroporous and strong base/gel type, Purolite A170 and Dowex 21K on the adsorption properties of Re(VII) ions were investigated experimentally and described by the isotherm, kinetic, and thermodynamic modeling. In ...
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The effects of the functional groups and structures of two different resins, weak base/macroporous and strong base/gel type, Purolite A170 and Dowex 21K on the adsorption properties of Re(VII) ions were investigated experimentally and described by the isotherm, kinetic, and thermodynamic modeling. In this regard, four widely used adsorption isotherm models including Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) were subjected to the sorption data in order to describe the reactions involved. Evaluating the correlation coefficients showed that the Freundlich and D-R isotherm models provided the best fit. The Langmuir isotherm capacities (qm) indicated that the perrhenate ion (ReO4-) adsorption was higher for the weak base/macroporous type resin rather than the others (166.67 mg/g and 142.86 mg/g, respectively). Moreover, the results of the EDX studies were in agreement with the previous results. Furthermore, the adsorption kinetics was demonstrated through fitting the data into different mechanisms, among which the pseudo-second-order mechanism was found to be successful for both resins; however, in the case of Dowex 21K, the rate of perrhenate ion uptake was more rapid than that for Purolite A170. Evaluation of the thermodynamic parameters also showed that the reaction mechanism was different for each case and that the adsorption of rhenium on Dowex 21K became more feasible with increase in temperature due to negative values for ΔH.
