Z. Piervandi; A. Khodadadi Darban; Seyed M. Mousavi; M. Abdollahi; Gh.R. Asadollahfardi; K. Akbari Noghabi
Abstract
Indigenous acidophilic bacteria separated from mine-waste can be used in return for the addition of the reagents like sulfuric acid. Among the tailings bacteria, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans are of the most-studied ones for the bioleaching and bioremediation of elements. ...
Read More
Indigenous acidophilic bacteria separated from mine-waste can be used in return for the addition of the reagents like sulfuric acid. Among the tailings bacteria, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans are of the most-studied ones for the bioleaching and bioremediation of elements. In this work, the isolation and characterization of the mentioned bacteria are studied by a proposed biochemical protocol. The sequential cultivation of the soil bacteria in a series of liquid media and solid cult
Laleh Sohbatzadeh; Sied Ziaedin Shafaei Tonkaboni; Mohammad Noaparast
Abstract
In this research work, with a simple, safe, and environmentally friendly approach to hydrometallurgy, a method for the recovery of lithium (Li), cobalt (Co), and nickel (Ni) from LIBs is suggested. The cathode materials are leached by malonic acid, as the leaching agent, and ascorbic acid, as the reducing ...
Read More
In this research work, with a simple, safe, and environmentally friendly approach to hydrometallurgy, a method for the recovery of lithium (Li), cobalt (Co), and nickel (Ni) from LIBs is suggested. The cathode materials are leached by malonic acid, as the leaching agent, and ascorbic acid, as the reducing agent in the first process, and by L-glutamic acid, as the leaching agent, and ascorbic acid, as the reducing agent in the second process. In order to optimize the leaching parameters including temperature, organic acid concentration, ascorbic acid concentration, type of organic acid, pulp density, and time, response surface methodology (RSM) of the experimental design process is used. According to the results, compared to L-glutamic acid in the second process, the leaching recovery increase considerably with malonic acid in the first process. This normally occurs due to the higher solubility of malonic acid in water, which results in a better complexation and a higher chelation rate. By contrast, as solubility of L-glutamic acid in water is low, metal-acid surface reaction and poor complexation are unavoidable. According to the statistical analysis of the results and validation testing, optimal experimental leaching occurs at the reaction temperature of 88 °C, organic acid concentration of 0.25 M, ascorbic acid concentration of 0.03 M, pulp density of 10 g/L, and leaching time of 2 h, via which metal recovery of 100% Li, 81% Co, and 99% Ni is achieved. Before and after acidic leaching, the sample active materials are qualitatively and quantitatively analyzed using X-ray diffraction, X-ray fluorescence, particle size analyzer, scanning electron microscope, energy dispersive spectroscopy, and atomic absorption spectroscopy.
Mineral Processing
Pedram Ashtari; Saeid Karimi; Seyyede Atefeh Hosseini
Abstract
In this research work, the reductive leaching of pyrolusite in a sulfuric acid medium with the aid of orange peel as a reductant was investigated. The important parameters affecting the leaching process include temperature in the range of 25 to 95 °C, the weight ratio of reducing agent to pyrolusite ...
Read More
In this research work, the reductive leaching of pyrolusite in a sulfuric acid medium with the aid of orange peel as a reductant was investigated. The important parameters affecting the leaching process include temperature in the range of 25 to 95 °C, the weight ratio of reducing agent to pyrolusite (R/P) in the range of 0 to 2 (w/w), and the concentration of sulfuric acid in the range of 0.05 to 0.25 M. According to the results, the parameters of temperature and the R/P are more significant in the reductive leaching process. With increasing temperature from 25 to 95 °C, Mn recovery increases from 0.5% to 52.5%. Also Mn recovery with a two-step increase in 0-0.1 and 0.1-1.5 of the R/P indicates a jump of 28.5% and 19.0%, respectively. Sulfuric acid concentration shows its effect by supplying sulfate and hydrogen ions in the leaching process. The successful use of orange peel as a reductant was confirmed by achieving a manganese dissolution efficiency of 98.1% under optimum conditions (temperature of 90 °C, sulfuric acid concentration of 0.1 M, and R/P ratio of 1.5 (w/w)). Kinetic investigations showed that the shrinking core model could not be used to determine the leaching mechanism of pyrolusite in the presence of fruit peel reductant. Avrami's kinetic model with very high fitting accuracy was used to determine the kinetic model of pyrolusite leaching.
Exploration
Mobin Saremi; Abbas Maghsoudi; Reza Ghezelbash; mahyar yousefi; Ardeshir Hezarkhani
Abstract
Mineral prospectivity mapping (MPM) is a multi-step and complex process designed to narrow down the target areas for exploratory activities in subsequent stages. To pinpoint promising zones of porphyry copper mineralization in the Varzaghan district, NW Iran, various exploration evidence layers were ...
Read More
Mineral prospectivity mapping (MPM) is a multi-step and complex process designed to narrow down the target areas for exploratory activities in subsequent stages. To pinpoint promising zones of porphyry copper mineralization in the Varzaghan district, NW Iran, various exploration evidence layers were employed in alignment with the conceptual model of these deposits. These layers encompass fault density, proximity to intrusive rocks, multi-element geochemical anomalies, and distances to phyllic and argillic alterations. The geochemical anomaly maps, recognized as the most effective layers, were generated through staged factor analysis (SFA) and the geochemical mineralization probability index (GMPI). Other layers were weighted using a logistic function, and their values were transformed into 0 -1 interval. Ultimately, to integrate the weighted layers, the fuzzy gamma operator and the geometric average method were applied. The normalized density index and prediction-area (P-A) plot were employed to evaluate the MPM models. The findings indicate that the developed models possess considerable validity and can be effectively utilized for planning future exploration endeavors.
Exploitation
Mohammad Sina Abdollahi; Mehdi Najafi; Alireza Yarahamdi Bafghi; Ramin Rafiee
Abstract
The stability analysis of chain pillars is crucial, especially as coal extraction rates increase, making it essential to reduce the size of these pillars. Therefore, a new method for estimating the load on chain pillars holds significant importance. This research introduces a novel solution for estimating ...
Read More
The stability analysis of chain pillars is crucial, especially as coal extraction rates increase, making it essential to reduce the size of these pillars. Therefore, a new method for estimating the load on chain pillars holds significant importance. This research introduces a novel solution for estimating side abutment load and analyzing the stability of chain pillars using the dynamic mode of the Coulmann Graphical (CG) method. The solution is implemented using Visual Studio software and is named Coulmann Chain Pillar Stability Analysis (CCPSA). The CG method is widely recognized in civil engineering as a highly efficient technique for determining soil side abutment pressure in both static and dynamic conditions. This method involves calculating the top-rupture wedge of chain pillars using the CG method. The CCPSA software functions share significant similarities with those of the Analysis Longwall Pillar Stability (ALPS) method. However, the main point of departure between the proposed method and the ALPS empirical method lies in their respective approaches to calculating side abutment load on chain pillars and evaluating subsidence conditions. The effectiveness of this method has been validated using a database of chain pillars from various mines worldwide and has been compared with the ALPS method. The results of the comparison demonstrate that the CCPSA is highly effective in evaluating chain pillar stability. This underscores the potential of the CG method and CCPSA software in providing valuable insights for assessing and ensuring the stability of chain pillars in mining operations.
Exploration
Zohre Hoseinzade; Mohammad Hassan Bazoobandi
Abstract
Anomaly detection is the process of recognizing patterns in data that differ from the typical behavior. In geochemistry, this involves identifying hidden patterns and unusual components within the context of exploratory target identification. This issue is particularly significant when limited information ...
Read More
Anomaly detection is the process of recognizing patterns in data that differ from the typical behavior. In geochemistry, this involves identifying hidden patterns and unusual components within the context of exploratory target identification. This issue is particularly significant when limited information is available about the area of interest. Therefore, employing methods that can aid in the exploration process under such conditions and with limited data is highly valuable. In this study, the Deep-Embedded Self-Organizing Map (DE-SOM), an unsupervised deep learning approach, was used to detect geochemical anomalies. The research focused on identifying multivariate geochemical anomalies in the Moalleman region. After detecting the region's geochemical anomalies, the effectiveness of the algorithm was assessed alongside two other types of SOM algorithms. For this purpose, the prediction area plot was utilized, with the intersection points for DE-SOM, Batch SOM, and SOM were determined to be 0.75, 0.67, and 0.65, respectively. The multivariate geochemical anomaly in the Moalleman area shows a good correlation with known mineral occurrences and the andesite and dacite units. Based on this, it can be stated that the DE-SOM method is a useful tool for identifying anomalies and patterns associated with mineralization.
Mineral Processing
Raheleh Hazrati; Shahram Rostami; Sadegh Marahem
Abstract
The components of low-grade bauxite were 28.4% silica, 34.9% alumina, 16.1% iron oxide as ferric oxide and 11.26% loss on ignition. Due to the high silica content of this type of bauxite, it couldn’t be processed by Bayer method. Therefore, a sintering method with limestone and sodium carbonate ...
Read More
The components of low-grade bauxite were 28.4% silica, 34.9% alumina, 16.1% iron oxide as ferric oxide and 11.26% loss on ignition. Due to the high silica content of this type of bauxite, it couldn’t be processed by Bayer method. Therefore, a sintering method with limestone and sodium carbonate was used for selective extraction of alumina. Experimental design was performed by surface response method (RSM) using central composite design. Selected parameters were temperature, soaking time, mole ratio of sodium oxide to alumina, mole ratio of calcium oxide to silica. The maximum amount of extraction of alumina from low-grade Jajarm bauxite by sintering method was 74.2%, which was obtained in the optimal values of the parameters as follows: A temperature of 1157°C, a soaking time of 35 minutes, a mole ratio of alkaline oxide (K2O + Na2O) of 1.25 and a mole ratio of calcium oxide to silica of 1.99. In 31 run experiments, the mixture of materials powder was transferred to an alumina crucible and heated in a muffle furnace at temperatures and soaking times determined by the experimental design. The sintered material was pulverized. The resulting powder was leached by 150 mL of a boiling alkaline solution (20 g/L NaOH + 20g/L Na2CO3) for 30 minutes at a stirring speed of 300rpm. Extracted aluminum from the leaching stage was analyzed by atomic absorption spectrometry.
Exploitation
Masoud Monjezi; Morteza Baghestani; Peyman Afzal; Ali Reza Yarahmadi Bafghi; Seyyed Ali Hashemi
Abstract
Blasting is an essential operation in mining projects, significantly affecting the particle-size distribution, which is critical for subsequent processes such as loading, hauling, and milling. Effectiveness of the blasting operations rely on accurate rock characterization, especially when dealing with ...
Read More
Blasting is an essential operation in mining projects, significantly affecting the particle-size distribution, which is critical for subsequent processes such as loading, hauling, and milling. Effectiveness of the blasting operations rely on accurate rock characterization, especially when dealing with different rock types. Proper rock and fragmentation characterization allows for tailored blast designs and also can lead to precise predictions of fragmentation quality. Various characterization techniques exist. This paper examines the application of fractal analysis to classify fragmentation quality and rock types, utilizing the Choghart iron mine in Iran as a case study. Extensive fieldwork collected data on rock properties (uniaxial compressive strength and density) and fragmentation outcomes during blasting. The fractal modeling revealed distinct breakpoints for classification, followed by Logratio analysis to assess relationships among the identified classes. Finally, mathematical models were established to predict fragmentation features based on the relevant rock attributes. The models demonstrated improved predictive accuracy as compared to the prior classifications.
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 ...
Read More
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 ...
Read More
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 ...
Read More
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. ...
Read More
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 ...
Read More
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. ...
Read More
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 ...
Read More
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
Mohammad Reza Shahverdiloo; Shokroallah Zare
Abstract
The deformation modulus of rock mass is necessary for stability analysis of rock structures, which is generally estimated by empirical models with one to five input parameters/indexes. However, appropriate input parameter participation to establish a sound basis for a reliable prediction has been a challenging ...
Read More
The deformation modulus of rock mass is necessary for stability analysis of rock structures, which is generally estimated by empirical models with one to five input parameters/indexes. However, appropriate input parameter participation to establish a sound basis for a reliable prediction has been a challenging task. In this study, the concept of the principal input parameters was developed based on an analytical method with an emphasis on in situ stress. Based on analytical methods, Young’s modulus of intact rock, the joint’s shear and normal stiffness, joint set spacing, and in situ stress are introduced as the main principal input parameters. A review of seventy empirical models revealed that most of them suffered from a lack of analytical parameters. Due to considering practical issues, the geological strength index (GSI) is replaced with joint set spacing; moreover, the in situ stress effect is perceived by combining Young’s modulus and joint stiffness with specific confining pressure and normal stress, respectively. The integration of the analytical base input parameters and practical issues enhanced the reliability of empirical models due to the reasonable prediction of the deformation modulus to numerical or analytical deformability analysis.
Rock Mechanics
Alireza Afradi; Arash Ebrahimabadi; Mansour Hedayatzadeh
Abstract
Tunnel Boring Machines (TBMs) are extensively used to excavate underground spaces in civil and tunneling projects. An accurate evaluation of their penetration rate is the key factor for the TBM performance prediction. In this study, artificial intelligence methods are used to predict the TBM penetration ...
Read More
Tunnel Boring Machines (TBMs) are extensively used to excavate underground spaces in civil and tunneling projects. An accurate evaluation of their penetration rate is the key factor for the TBM performance prediction. In this study, artificial intelligence methods are used to predict the TBM penetration rate in excavation operations in the Kerman tunnel and the Gavoshan water conveyance tunnels. The aim of this paper is to show the application of the Multivariate Linear Regression (MLR), Artificial Neural Network (ANN), and Support Vector Machine (SVM) for the TBM penetration rate prediction. The penetration rate parameter is considered as a dependent variable, and the Rock Quality Designation (RQD), Brazilian Tensile Strength (BTS), Uniaxial Compressive Strength (UCS), Density (D), Joint Angle (JA), Joint Spacing (JS), and Poisson's Ratio are considered as independent variables. The obtained results by the several proposed methods indicated a high accuracy between the predicted and measured penetration rates, but the support vector machine yields more precise and realistic outcomes.
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 ...
Read More
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 ...
Read More
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; ...
Read More
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, ...
Read More
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 ...
Read More
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.
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 ...
Read More
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.
Mine Economic and Management
Mahdi Pouresmaieli; Mohammad Ataei; Ali Nouri Qarahasanlou; Abbas Barabadi
Abstract
The mining industry operates in a complex and dynamic environment and faces many challenges that can negatively affect sustainable development goals. To avoid these effects, mining needs to adopt strategic decisions. Therefore, it requires effective decision-making processes for resource optimization, ...
Read More
The mining industry operates in a complex and dynamic environment and faces many challenges that can negatively affect sustainable development goals. To avoid these effects, mining needs to adopt strategic decisions. Therefore, it requires effective decision-making processes for resource optimization, operational efficiency, and sustainability. Multicriteria decision-making methods (MCDM) have been considered valuable decision-support tools in the mining industry. This article comprehensively examines MCDM methods and their applications in the mining industry. This article discusses the basic principles and concepts of MCDM methods, including the ability to prioritize and weigh conflicting, multiple criteria and support decision-makers in evaluating diverse options. According to the results, 1579 MCDM articles in mining have been published from the beginning to April 15, 2023, and a scientometric analysis was done on these articles. In another part of this article, 19 MCDM methods, among the most important MCDM methods in this field, have been examined. The process of doing work in 17 cases of the reviewed methods is presented visually. Overall, this paper is a valuable resource for researchers, mining industry professionals, policymakers, and decision-makers that can lead to a deeper understanding of the application of MCDM methods in mining. By facilitating informed decision-making processes, MCDM methods can potentially increase operational efficiency, resource optimization, and sustainable development in various mining sectors, ultimately contributing to mining projects' long-term success and sustainability.
Exploration
Mina Shafiabadi; Abolghasem Kamkar Rouhani
Abstract
Considering the effect of fractures in increasing hydrocarbon recovery, the study of reservoir rock fractures is of particular importance. Fractures are one of the most important fluid flow paths in carbonate reservoirs. Image logs provide the ability to detect fractures and other geological features ...
Read More
Considering the effect of fractures in increasing hydrocarbon recovery, the study of reservoir rock fractures is of particular importance. Fractures are one of the most important fluid flow paths in carbonate reservoirs. Image logs provide the ability to detect fractures and other geological features and reservoir layers. In this study, two approaches were used to detect fractures using FMI image log in two wells A and B located in one of oilfields in southwest of Iran. In the first stage, the correction and processing of the FMI raw data were carried out to identify the number and position of fractures, as well as the dip, extension, classification, and density of fractures. In the second step, by considering that the fractures possess the edges in the FMI images, various edge detection filters such as Prewitt, Canny, Roberts, LOG, Zero-cross and Sobel were applied on the image data, and then, their performances for identification of fractures were compared. Finally, the automatic identification of fractures was done by applying the Hough transform algorithm and the results showed that Canny algorithm was the best option to perform Hough transformation. The comparison of the efficiency of the above-mentioned edge detection filters for identification of fractures, and more importantly, the automatic identification of fractures using the Hough transform algorithm can be considered as the novelty of this research work.
