Rock Mechanics
Dariush Mohammadi; Kourosh Shahriar; Parviz Moarefvand; Ebrahim Farrokh
Abstract
The correct design of the cutterhead of a tunnel boring machine (TBM) plays a vital role in the efficient operation of the machine, as the cutterhead structure remains unchanged during the tunneling project. This paper aims to elucidate the fundamental principles in the design of the cutterhead opening ...
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The correct design of the cutterhead of a tunnel boring machine (TBM) plays a vital role in the efficient operation of the machine, as the cutterhead structure remains unchanged during the tunneling project. This paper aims to elucidate the fundamental principles in the design of the cutterhead opening in soft ground based on data obtained from TBM manufacturers. Initially, a comprehensive database of soft ground cutterheads from different TBM manufacturers across various projects and ground conditions was compiled. The most frequently used cutterhead configurations with diameters exceeding 5 meters were categorized into 36 distinct opening configurations based on a radial opening ratio curve and opening patterns per sector. Next, the performance parameters and particle flow characteristics of three Herrenknecht cutterhead designs featuring varying opening configurations in the central and circumference areas were analyzed using the Discrete Element Method (DEM) by considering material parameters for machine and soil and contact parameters between soil particles and soil particles-machine structures. Hertz–Mindlin model was assigned as the contact model for these elements. Additionally, three different cutterheads employed in Tehran metro projects in Iran were identified by monitoring the cutterhead torque and thrust force under same geotechnical conditions and operational parameters. Generally, a higher opening percentage in the central area of the cutterhead indicates good performance during excavation in cohesive soils. However, the higher opening percentage in circumferential areas is a better choice for effective excavated material removal around the cutterhead and tunnel in non-cohesive soils, weathered rocks, mixed and heterogeneous conditions.
Environment
Abdollah Yazdi; rahim dabiri; Habib Mollai
Abstract
Geosites and their contents including minerals, fossils, etc. can strongly represent the history of a region. They greatly help our understanding of the evolution of Earth, volcanic activities, plate tectonics, and the characteristics of different environments. These are some of the vital information ...
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Geosites and their contents including minerals, fossils, etc. can strongly represent the history of a region. They greatly help our understanding of the evolution of Earth, volcanic activities, plate tectonics, and the characteristics of different environments. These are some of the vital information about 4500 million years of the Earth's life, and are our common international heritage. Geoconservation’s main purpose is the protection of geosites as major units of geoheritage, and this principle is achieved through the application of specific methods such as indexing geological phenomena, assessment, preservation, valuation, and estimating the importance of each geosite, as well as monitoring (or watching these phenomena). In this paper, geoconservation is introduced as a specialized and essential branch of geological science, which is currently under development. Therefore, geoconservation principles are presented here, and their relation to other geosciences is discussed. In addition, through scientific and cultural education related to sustainable development (in regard to the geoscience), citizens can be informed that lack of conserving natural resources would reduce geo-resources, and on the other hand, is a serious threat to geoheritage of the planet Earth. This crucial subject can be achieved by making information available and by teaching skills by which making prospective and correct decisions is possible.
M. Abedini; M. Ziaii; Y. Negahdarzadeh; J. Ghiasi-Freez
Abstract
The porosity within a reservoir rock is a basic parameter for the reservoir characterization. The present paper introduces two intelligent models for identification of the porosity types using image analysis. For this aim, firstly, thirteen geometrical parameters of pores of each image were extracted ...
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The porosity within a reservoir rock is a basic parameter for the reservoir characterization. The present paper introduces two intelligent models for identification of the porosity types using image analysis. For this aim, firstly, thirteen geometrical parameters of pores of each image were extracted using the image analysis techniques. The extracted features and their corresponding pore types of 682 pores were used for training two intelligent models, BPN (back-propagation network) and SAE (stacked autoencoder). The trained models take the geometrical properties of pores to classify the type of six porosity types including intra-particle, inter-particle, vuggy, moldic, biomoldic, and fracture. The MSE values for the BPN and SAE models were found to be 0.0042 and 0.0038, respectively. The precision, recall, and accuracy of the intelligent models for classifying the types of pores were calculated. The BPN model was able to correctly recognize 193 intra-particle pores out of 197 ones, 45 inter-particle pores out of 50 ones, 7 vuggy pores out of 9 ones, 10 moldic pores out of 12 ones, 2 biomoldic pores out of 3 ones, and 6 fractures out of 7 ones. Also the SAE model was able to correctly classify 193 intra-particle pores out of 197 ones, 46 inter-particle pores out of 50 ones, 8 vuggy pores out of 9 ones, 10 moldic pores out of 12 ones, 3 biomoldic pores out of 3 ones, and 7 fractures out of 7 ones. The results obtained showed that the SAE model carried out a bit more accuracy for classification of the inter-particle, vuggy, biomoldic, and fracture pores.
Rock Mechanics
Seyed M. Fatemi Aghda; M. Kianpour; M. Talkhablou
Abstract
In this research, the relationship between P-wave velocity (Vp) and Electrical Resistivity (ER) parameters with rock mass quality indices is investigated; parameters such as rock mass quality classification (Q) and modified system for sedimentary rocks, known as Qsrm. For making predictive models, about ...
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In this research, the relationship between P-wave velocity (Vp) and Electrical Resistivity (ER) parameters with rock mass quality indices is investigated; parameters such as rock mass quality classification (Q) and modified system for sedimentary rocks, known as Qsrm. For making predictive models, about 1200 data-sets extracted from sections drilled in Seymareh and Karun 2 Dam Sites (SDS and KDS) in Asmari Formation, south-west Iran. Statistical and fuzzy methods used to study the relationships between physical characteristics and rock mass quality. Since in Qsrm classification, the existence of cavities, layering and rock texture is considered in addition to the parameters considered in the Q classification; therefore, it provides a better description of rock mass and is closely related with Vp and ER parameters. The obtained equations for predicting Q and Qsrm showed the determination coefficients (R2) 0.48 and 0.67, respectively, and the coefficient of determination 0.86 for Qsrm calculated from the fuzzy model. Finally, Mean Absolute Deviation (MAD), Variance Accounted For (VAF) and Root Mean Square Error (RMSE) used to check the prediction performance of statistical and fuzzy methods. The results of the calculated errors also showed that fuzzy models are interesting because they have good accuracy for predicting Qsrm. In addition, by increasing the degree of karstifiction, the efficiency of the geophysical method for estimate of Q decreases rapidly, this is due to ignoring the cavities in these categories.
Seyyed S. Ghannadpour; A. Hezarkhani
Abstract
In several uranium (U) prospecting projects in Iran, particularly Central Iran, the association and enrichment of rare earth elements (REEs) are known as the usual features. Sometimes the association of REEs and U with high economic perspective has caused that the relation between the rare earth and ...
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In several uranium (U) prospecting projects in Iran, particularly Central Iran, the association and enrichment of rare earth elements (REEs) are known as the usual features. Sometimes the association of REEs and U with high economic perspective has caused that the relation between the rare earth and radioactive elements is taken into consideration in other types of mineralization, and if there is any relation, radioactivity will be applied in the exploration of REEs. In the current work, sampling from Baghak anomaly in the Sangan mines is carried out based on the radioactivity and radiation measurement methods (as the optimal sampling pattern). In fact, the goal of this work is to survey the presence or absence of such a relation in a skarn mine, which is a different case study from Central Iran. In the case of presence, this will lead to a new exploration method and sampling pattern for REEs. The mineralogical studies (based on the optical and electronic microscopic observations), statistical investigations, and geochemical analyses are applied in this research work. The results obtained from the statistical studies show that the Baghak anomaly due to involving a significant amount of U, Ce, and La and a high concentration of REEs can be considered as one of the important mines. Spider diagrams and their geochemical investigations include the features that are typical of the subduction-related magmas in the calcalkaline volcanic arcs of the continental active margins. The chondrite-normalized REE pattern shows the enrichment of LREE, and a positive pattern close to flat HREE due to the entry of LREE ions into the allanites network. The mineralogical study results also confirm that REEs (especially Ce) are accumulated as a solid solution in the allanite minerals. Moreover, from the mineralogical, geochemical, and statistical analyses, it can be observed that in addition to the presence of such a relation in the mentioned mineralization (Central Iran mineralizations), there is an acceptable correlation between these elements in the Baghak iron-skarn mineralization. Eventually, it can be said that the idea and introduced method for the exploration of REEs in this work could present a new viewpoint to the decision-makers of this industry.
J. Abdollahei Sharif; A. Jafarpour; S. Yousefi
Abstract
The computer-based 3D modeling of ore bodies is one of the most important steps in the resource estimation, grade determination, and production scheduling of open-pit mines. In the modeling phase, the volume of the orebody model is required to be filled by the blocks and sub-blocks. The determination ...
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The computer-based 3D modeling of ore bodies is one of the most important steps in the resource estimation, grade determination, and production scheduling of open-pit mines. In the modeling phase, the volume of the orebody model is required to be filled by the blocks and sub-blocks. The determination of Block Size (BS) is important due to the dependence of the geostatistical issues and calculations related to mining capabilities on it. There are some factors effective in the determination of an optimal BS including the metal content, estimation error, recovery percentage, mining ability, safety, and dilution. In this work, an optimal BS is determined using a two-stage approach. In the proposed approach, the Fuzzy Delphi Analytic Hierarchy Process (FDAHP) and Fuzzy Multi-Objective Optimization by Ratio Analysis (FMOORA) methods are used. In the first phase, the weight of each criterion is calculated based on the opinions of the experts using the FDAHP method. In the second phase, the FMOORA method is applied in order to determine a suitable BS for the design and operation of mining considering the extracted weights in the previous phase. The block model of the Sungun copper mine is studied as a case study to evaluate the capability of the proposed approach. The results of implementation of this approach are desirable because of converting the opinions of the experts to fuzzy values, weighing the experts according to the experience and technical knowledge, weighting the criteria by FDAHP, and choosing the optimal option with FMOORA. Furthermore, the 12.5×12.5×12.5 m3 block (A5) is chosen as an appropriate BS, which is compatible with the real conditions of the studied mine.
Zohreh Nabavi; Mohammad Mirzehi; Hesam Dehghani; Pedram Ashtari
Abstract
Back-break is one of the adverse effects of blasting, which results in unstable mine walls, high duration, falling machinery, and inappropriate fragmentation. Thus, the economic benefits of the mine are reduced, and safety is severely affected. Back-break can be influenced by various parameters such ...
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Back-break is one of the adverse effects of blasting, which results in unstable mine walls, high duration, falling machinery, and inappropriate fragmentation. Thus, the economic benefits of the mine are reduced, and safety is severely affected. Back-break can be influenced by various parameters such as rock mass properties, blast geometry, and explosive properties. Therefore, during the blasting process, back-break must be accurately predicted, and other production activities must be done to prevent and reduce its adverse effects. In this regard, a hybrid model of extreme gradient boosting (XGB) is proposed for predicting back-break using gray wolf optimization (GWO) and particle swarm optimization (PSO). Additionally, validation of the hybrid model is conducted using XGBoost, gene expression programming (GEP), random forest (RF), linear multiple regression (LMR), and non-linear multiple regression (NLMR) methods. For this purpose, the data obtained from 90 blasting operations in the Chadormalu iron ore mine are collected by considering the parameters of the blast pattern design. According to the results obtained, the performance and accuracy level of hybrid models including GWO-XGB (R2 = 99, RMSE = 0.01, MAE = 0.001, VAF = 0.99, a-20 = 0.98), and PSO-XGB (99, 0.01, 0.001, 0.99, 0.98) are better than the XGBoost (97, 0.185, 0.132, 0.98, 95), GEP (96, 0.233, 0.186, 0.967, 0.935), RF (97, 0.210, 0.156, 0.97, 0.94), LMR (96, 0.235, 0.181, 0.964, 0.92), and NLMR (96, 0.229, 0.177, 0.968, 0.93) models. Notably, the GWO-XGB hybrid model has superior overall performance as compared to the PSO-XGB model. Based on the sensitivity analysis results, hole depth and stemming are the essential effective parameters for back-break.
Exploration
Rashed Pourmirzaee; Hadi Jamshid Moghaddam
Abstract
In recent years, hyperspectral data have been widely used in earth sciences because these data provide accurate spectral information of the earth's surface. This research aims to apply match filtering (MF) on Hyperion hyperspectral imagery for mapping alteration mineral in the Astarghan area, NW Iran. ...
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In recent years, hyperspectral data have been widely used in earth sciences because these data provide accurate spectral information of the earth's surface. This research aims to apply match filtering (MF) on Hyperion hyperspectral imagery for mapping alteration mineral in the Astarghan area, NW Iran. Astarghan is located in the northwest of Iran where deposits of low-sulfide gold-bearing ore rocks occur as veins and stockworks. Therefore, at first, the Astarghan Hyperion scene was topographically and atmospherically corrected. Then, the data quality was surveyed to recognize bad bands and improve the accuracy of the subsequent processing steps. In MF analysis, it is a challenge to separate MF abundance images to target and background pixels. Therefore, to cope with this challenge, a moving threshold technique is proposed. The results indicated three indicative minerals including kaolinite, opal and jarosite. Then, the results were statistically verified by virtual verification and geological data. The verification was performed virtually using United States Geological Survey (USGS) spectral library data, which showed an agreement of 78.06%. Moreover, a comparison of the MF analysis results showed a good agreement with field investigations and overlaying with a detailed geological map of the study area. Finally, in this study the X-ray diffraction (XRD) of three indicative mineral samples was used to check the efficiency of the applied method.
Rock Mechanics
Ghorban Khandouzi; Mohammad Hossein Khosravi
Abstract
Granular materials used in engineering structures tend to experience arching under different geotechnical factors. Arching is a factor of load transfer from the destroyed zone to stable areas in these structures. Soil arching plays an important role in stress redistribution, settlement, and load on supports ...
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Granular materials used in engineering structures tend to experience arching under different geotechnical factors. Arching is a factor of load transfer from the destroyed zone to stable areas in these structures. Soil arching plays an important role in stress redistribution, settlement, and load on supports in tunneling. This paper reviews the effect of various parameters on the development of soil arching and formation of expansion and contraction zones around the tunnel. A comprehensive literature review, analysis of new published papers, and investigations were conducted to study the effects of various parameters on soil arching. The results were obtained by studying the formation of shear bands, deformed zones, and their development. The achieved results of investigations show that soil arching and ground deformation around tunnels in sandy grounds are complex phenomena that require careful consideration during tunnel construction. Also the results reveal that despite the arching zone, a loosened zone with non-linear slip surfaces forms above the tunnel. With the onset of tunnel convergence, initial non-linear sliding surfaces appear, and the arching area forms above the tunnel. When tunnel convergence increases, a stable arch forms inside the arching zone, and a de-stressed area as a loosened zone is created under the stable arch. Understanding of soil arching, ground deformation, and the stable arch formed inside the arching zone around tunnels in sandy grounds is very important for the engineers evaluating stress redistribution and load on tunnel supports. Also understanding these issues can help the designers and practitioners make informed decisions during tunnel construction.
Rock Mechanics
H.C. ZHAO; H.J. An; M.S. Gao
Abstract
Both the deformation characters and the failure mode of the large cross-sectional longwall installation roadway under compound roof are becoming an emergent issue than ever before due to the rapid development of modern mining equipment. Various engineering applications have revealed that the insufficient ...
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Both the deformation characters and the failure mode of the large cross-sectional longwall installation roadway under compound roof are becoming an emergent issue than ever before due to the rapid development of modern mining equipment. Various engineering applications have revealed that the insufficient design and inappropriate support technology are the main reasons for the fatal accidents associated with the sudden roof fall attributed to the separation of the overlying compound strata. The present research work, therefore, starts with a case study using the conventional support technology in order to demonstrate the importance of this issue followed by a summarization of the typical failure mode of the longwall installation roadway under compound strata with varied thicknesses. Then a simplified theoretical model is proposed and set up aiming at a better understanding of the distribution of the elastic-plastic zones as well as the effects of different caving procedures. The finite element analysis software program FLAC3D is adopted to evaluate the effect of the caving method and the reinforcement provided by an additional support. Then a case study conducted at a typical coal mine with compound roof condition is presented to verify the advantages of the proposed design. The results obtained show that the optimized design presented in this research work is effective to control the deformation of the surrounding rock, particularly in terms of separation of the overlying compound strata.
Mineral Processing
M. R. Khani; M. Karamoozian
Abstract
In the present work, we investigated and optimized the digestion efficiency, A/S (Al2O3/SiO2 in red mud), and N/S (Na2O/SiO2 in red mud) of mixed bauxite in Iran Alumina Company using the Bayer process. Digestion experiments were carried out in an induction rotary autoclave on a mix of Jajarm, Yazd, ...
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In the present work, we investigated and optimized the digestion efficiency, A/S (Al2O3/SiO2 in red mud), and N/S (Na2O/SiO2 in red mud) of mixed bauxite in Iran Alumina Company using the Bayer process. Digestion experiments were carried out in an induction rotary autoclave on a mix of Jajarm, Yazd, Tash, and Shirin Cheshmeh bauxites. A 4-factor 3-level response surface methodology was applied for the design and analysis of the experiment with the optimization of Na2O concentration, digestion temperature, residence time, and amount of lime addition. Towquadratics and one linear model were derived for the prediction of digestion efficiency, and A/S and N/S responses. The results obtained showed that the optimum amounts for Na2O concentration, temperature, amount of lime addition and residence time were 180 g/L, 275°C, 7.73%, and 50 minutes, respectively, in which the digestion efficiency, A/S, and N/S reached 72.05%, 1.169, and 0.27, respectively. Validation experiment showed that the digestion efficiency, A/S, and N/S were 72.24%, 1.162, and 0.28% respectively, which meant a 2% increase in digestion efficiency and a 0.09 and 0.02 decrease in A/S and N/S, respectively, compared to the current operating condition.
J. Vazifeh Mehrabani; M. Goharkhah
Abstract
In the current research work, a piping system is designed for slurry transport to the tailing dam in the Kooshk lead-zinc mine, Iran. The experiments are carried out primarily to investigate the rheological behavior of the slurry at different densities and obtain a non-Newtonian model for the shear stress ...
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In the current research work, a piping system is designed for slurry transport to the tailing dam in the Kooshk lead-zinc mine, Iran. The experiments are carried out primarily to investigate the rheological behavior of the slurry at different densities and obtain a non-Newtonian model for the shear stress variation with the deformation rate. It is shown that the shear stress of concentrated slurry follows the plastic Bingham model. The results obtained also indicate the increasing trend of the yield stress and the apparent viscosity of the slurry with the density. Appropriate correlations are proposed for the apparent viscosity and yield stress as a function of pulp concentration. At the next step, the required design parameters such as the slurry flow rate, pressure drop, critical velocity, and minimum required head for flow initiation and head losses are calculated for different slurry densities and pipe sizes. The appropriate piping system is finally designed based on the experimental data and the calculated parameters. It is concluded that the 3 in diameter pipe can be used to deliver the slurry with solid concentrations between 44% < Cw < 60% by weight, without a pumping system.
Gh. Khandouzi; H. Memarian; M. H. Khosravi
Abstract
The dynamic fracture characteristics of rock specimens play an important role in analyzing the fracture issues such as blasting, hydraulic fracturing, and design of supports. Several experimental methods have been developed for determining the dynamic fracture properties of the rock samples. However, ...
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The dynamic fracture characteristics of rock specimens play an important role in analyzing the fracture issues such as blasting, hydraulic fracturing, and design of supports. Several experimental methods have been developed for determining the dynamic fracture properties of the rock samples. However, many used setups have been manufactured for metal specimens, and are not suitable and efficient for rocks. In this work, a new technique is developed to measure the dynamic fracture toughness of rock samples and fracture energy by modifying the drop weight test machine. The idea of wave transmission bar from the Hopkinson pressure bar test is applied to drop weight test. The intact samples of limestone are tested using the modified machine, and the results obtained are analyzed. The results indicate that the dynamic fracture toughness and dynamic fracture energy have a direct linear relationship with the loading rate. The dynamic fracture toughness and dynamic fracture energy of limestone core specimens under the loading rates of 0.12-0.56kN/µS are measured between 9.6-18.51MPa√m and 1249.73-4646.08J/m2, respectively. In order to verify the experimental results, a series of numerical simulation are conducted in the ABAQUS software. Comparison of the results show a good agreement where the difference between the numerical and experimental outputs is less than 4%. It can be concluded that the new technique on modifying the drop weight test can be applicable for measurement of the dynamic behavior of rock samples. However, more tests on different rock types are recommended for confirmation of the application of the developed technique for a wider range of rocks.
Mahyar Yousefi; Samaneh Barak; Amir Salimi; Saeed Yousefi
Abstract
In this paper, we discuss the concepts behind dispersion patterns of geochemical anomalies when applied for prospecting mineral deposits in different exploration scales. The patterns vary from regional to local scale geochemical surveys, which is due to the differences in the corresponding underlying ...
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In this paper, we discuss the concepts behind dispersion patterns of geochemical anomalies when applied for prospecting mineral deposits in different exploration scales. The patterns vary from regional to local scale geochemical surveys, which is due to the differences in the corresponding underlying processes. Thus the ways for modelling the dispersion patterns and driving significant geochemical signatures should consider the variety when the area under study are delimited from regional to deposit scales exploration. Subsequently, this paper faces with two questions, namely (1) should various geochemical indicators be integrated in different exploration scales aiming at introducing stronger signatures of mineral deposits? and (2) how does the exploration scale affect dispersion patterns of geochemical indicator elements? We demonstrate that the exploration scale plays an important role on the reliability and usefulness of geochemical anomaly models. In this regard, although fusion may achieve reputable outcomes at regional scale exploration, we demonstrate that integration doesn’t gain accurate results for exploration at local scale, which is due to the diversities of the elemental distributions in the two different scales. This achievement is approved by comparing two geochemical signatures, one obtained by integration of two different indicator factors and the other one that used a single factor. The former produces almost the whole studied area as prospective, while the later recognizes ~10% of the area for further exploration, which is closely related to the porphyry Cu mineralization and is verified by drilling results.
M.R. Shahverdi; A. Khodadadi Darban; M. Abdollahy; Yadollah Yamini
Abstract
Flotation is a common process in sulfide ore beneficiation. Due to the restrictions and lack of access to high-quality water sources for industrial purposes, recycled water plays an important role in the flotation processes. Due to the existence of various organic and inorganic substances in the process, ...
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Flotation is a common process in sulfide ore beneficiation. Due to the restrictions and lack of access to high-quality water sources for industrial purposes, recycled water plays an important role in the flotation processes. Due to the existence of various organic and inorganic substances in the process, water influences the flotation performance. In this work, the effect of accumulation of sulfate ion in processed water on galena flotation was investigated. Flotation experiments using processed water without sulfate ion led to a concentrate containing 40.7% of lead and a maximum recovery of 58.9%. The presence of higher sulfate ion levels (2000 M) in processed water caused a significant decrease in the grade and recovery of the lead concentrate. With 2000 mg/L of sulfate ion, the grade and recovery of lead decreased from 40.7 to 24.3% and from 58.9 to 32.1 %, respectively. Thermodynamic calculations showed that when the sulfate ion concentration was increased from 300 to 2000 ppm, it was more likely that lead sulfate (solid) was formed. With increase in the xanthate ion concentration from 10-6 to 10-4 M, could be substituted by . On the basis of the results obtained, it was concluded that in order to reduce the negative effects of sulfate ion accumulation in water and increase the efficiency of the galena flotation process, higher dosages of xanthates should be added to the system.
Rock Mechanics
J. Mohammadi; M. Ataei; R. Kakaie; R. Mikaeil; S. Shaffiee Haghshenas
Abstract
Prediction of the production rate of the cutting dimensional stone process is crucial, especially when chain saw machines are used. The cutting dimensional rock process is generally a complex issue with numerous effective factors including variable and unreliable conditions of the rocks and cutting machines. ...
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Prediction of the production rate of the cutting dimensional stone process is crucial, especially when chain saw machines are used. The cutting dimensional rock process is generally a complex issue with numerous effective factors including variable and unreliable conditions of the rocks and cutting machines. The Group Method of Data Handling (GMDH) type of neural network and Radial Basis Function (RBF) neural network, as two kinds of the soft computing method, are powerful tools for identifying and assessing the unpredicted and uncertain conditions. Hence, this work aims to develop prediction models for estimating the production rate of chain saw machines using the RBF neural network and GMDH type of neural network, and then to compare the results obtained from the developed models based on the performance indices including value account for, root mean square error, and coefficient of determination. For this purpose, the parameters of 98 laboratory tests on 7 carbonate rocks are accurately investigated, and the production rate of each test is measured. Some operational characteristics of the machines, i.e. arm angle, chain speed, and machine speed, and also the three important physical and mechanical characteristics including uniaxial compressive strength, Los Angeles abrasion test, and Schmidt hammer (Sch) are considered as the input data, and another operational characteristic of the machines, i.e. production rate, is considered as the output dataset. The results obtained prove that the developed GMDH model is able to provide highly promising results in order to predict the production rate of chain saw machines based on the performance indices.
Exploration
Seyyed Saeed Ghannadpour; Samaneh Esmaelzadeh Kalkhoran; Maedeh Behifar; Hadi Jalili
Abstract
In this study, with the aim of identifying alteration zones related to the porphyry copper system, satellite images are processed in study area (the Zafarghand exploration area) in the NE of Isfahan. For this purpose, one of the common methods of separating geochemical anomalies from the background, ...
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In this study, with the aim of identifying alteration zones related to the porphyry copper system, satellite images are processed in study area (the Zafarghand exploration area) in the NE of Isfahan. For this purpose, one of the common methods of separating geochemical anomalies from the background, i.e. fractal Concentration-Number (C-N) model, has been employed. The C-N fractal model will normally be implemented on geochemical samples. While in this study, the digital number values belonging to the pixels of the ASTER sensor image are considered as a systematic sample network and also as input for this model. The output of this processing has been prepared in the form of maps of promising areas of the Zafarghand region. The correspondence of the resulting maps with the alteration map of the region shows that applying the proposed method in determining the propylitic and phyllic alteration zones has had acceptable performance. Finally, with the help of the aforementioned proposed method, a map of the promising areas of the study area has been prepared, and based on that, new zones of alterations have been introduced in the region.
Rock Mechanics
Sajjad Khalili; Masoud Monjezi; Hasel Amini Khoshalan; Amir Saghat foroush
Abstract
Determining the appropriate blasting pattern is important to prevent any damage to the tunnel perimeter in conventional tunneling by blasting operation in hard rocks. In this research work, the LS-DYNA software and numerical finite element method (FEM) are used for simulation of the blasting process ...
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Determining the appropriate blasting pattern is important to prevent any damage to the tunnel perimeter in conventional tunneling by blasting operation in hard rocks. In this research work, the LS-DYNA software and numerical finite element method (FEM) are used for simulation of the blasting process in the Miyaneh-Ardabil railway tunnel. For this aim, the strong explosive model and nonlinear kinematic plastic material model are considered. Furthermore, the parameters required for the Johnson-Holmquist behavioral model are based on the Johnson-Holmquist-Ceramic material model relationships and are determined for the andesitic rock mass around studied tunnel. The model geometry is designed using AUTOCAD software and Hyper-mesh software is applied for meshing simulation. After introducing elements properties and material behavioral models and applying control and output parameters in LS-PrePost software, the modeling process is performed by LS-DYNA software. Different patterns of blastholes including 66, 23, and 19 holes, with diameters of 40 and 51 mm, and depths of 3 to 3.8 m are investigated by three-dimensional FEM. The borehole pressure caused by the ammonium nitrate-fuel oil (ANFO) detonation is considered based on the Jones-Wilkins-Lee (JWL) equation of state in the LS-DYNA software. The outer boundaries of the model are considered non-reflective to prevent the wave’s return. The results showed that LS-DYNA software can efficiently simulate the blasting process. Moreover, the post-failure rate of the blasting is reduced by more than 30% using the main charge with less explosive power and reducing the distance and diameter of contour holes.
H. hadizadeh Ghaziania; M. Monjezi; A. Mousavi; H. Dehghani; E. Bakhtavar
Abstract
The production cycle in open-pit mines includes the drilling, blasting, loading, and haulage. Since loading and haulage account for a large part of the mining costs, it is very important to optimize the transport fleet from the economic viewpoint. Simulation is one of the most widely used methods in ...
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The production cycle in open-pit mines includes the drilling, blasting, loading, and haulage. Since loading and haulage account for a large part of the mining costs, it is very important to optimize the transport fleet from the economic viewpoint. Simulation is one of the most widely used methods in the field of fleet design. However, it is unable to propose an optimized scenario for which the appropriate metaheuristic method should be employed. This paper considers the Sungun copper mine as the case study, and attempts to find the most feasible transportation arrangement. In the first step, in this work, we compare the flexible dispatching with the fixed allocation methods using the Arena software. Accordingly, the use of flexible dispatching reveals the increase in the production rate (20%) and productivity (25%), and the decrease (20%) in the idle time. The firefly metaheuristic algorithm used in the second step shows that the combined scenario of the 35-ton and 100-ton trucks is the most suitable option in terms of productivity and cost. In another attempt, comparing different heterogeneous truck fleets, we have found that the scenarios 35-100 and 35-60-100-144 increase the production rate by 39% and 49%, respectively. Also, in both scenarios, the production cost decreases by 11% and 21%, respectively.
E. Nemattolahi; A.R. Ghasemi; E. Razi; S. Banisi
Abstract
The discrete element method (DEM) has been used as a popular simulation method in order to verify the designs by visualizing how materials flow through complex equipment geometries. Although DEM simulation is a powerful design tool, finding a DEM model that includes all real material properties ...
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The discrete element method (DEM) has been used as a popular simulation method in order to verify the designs by visualizing how materials flow through complex equipment geometries. Although DEM simulation is a powerful design tool, finding a DEM model that includes all real material properties is not computationally feasible. In order to obtain more realistic results, particle energy loss due to rolling friction has been highlighted by many researchers using various models to implement a reverse torque. On account of the complexity of the problem, there is no unique model for all applications (i.e. dynamic and pseudo-static regimes). In this research work, an in-house developed DEM software (KMPCDEM©) was used to assess the robustness of three models by comparing the repose angle obtained through the draw down test. The elastic–plastic spring dashpot model was then modified based on considering the individual parameters instead of the relative parameters of two contact entities. The results showed that the modified model could produce a higher repose angle. The modified model was used for the calibration of DEM input parameters in the simulation of repose angle of iron ore pellets in a laboratory setup of the draw down test. Comparison of the calibrated DEM simulation (using 0.0007 and 0.75 for the rolling and sliding friction coefficients, respectively) with the laboratory results showed a good agreement between the predicted and measured angle of repose. The non-calibrated DEM simulations are susceptible to error, and therefore, it is strongly recommended to use the laboratory experiments to characterize the materials before using the DEM simulation as a design tool of industrial equipment.
Mahdi Malakoutikhah; Hamed Nezafat; Masoud Ashoogh; Erfan Hayati; Hosein Mirzamohammadi; Valiallah Karimi Gogheri; Hadiseh Rabiei
Abstract
Due to the high number and severity of tire burst accidents of dump trucks, the present work is conducted to identify and prioritize the effective causes of dump truck tire bursts using the fuzzy best-worst method (FBMW). The present work is conducted using content analysis and FBMW. First, by using ...
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Due to the high number and severity of tire burst accidents of dump trucks, the present work is conducted to identify and prioritize the effective causes of dump truck tire bursts using the fuzzy best-worst method (FBMW). The present work is conducted using content analysis and FBMW. First, by using focus groups and exploring the texts and events, and then these factors are weighted and then prioritized using FBMW. The results of the first phase show that the factors affecting the bursting of dump truck tires can be classified into 5 main categories of road conditions (six sub-categories), maintenance (six sub-categories), monitoring, and inspection (10 sub-categories), unsafe behavior (seven sub-categories), and tire conditions (five sub-categories). The results of the second phase also show that the tire conditions and unsafe behavior are the most important factors with a mean weight of 0.2252 and 0.1681, respectively. The results of the present work show that the most important cause is the monitoring of temperature, pressure, and tire conditions. Therefore, it can be concluded that in order to reduce these accidents, in addition to choosing the right tire, the conditions such as temperature and pressure inspection should be given a high attention.
Rock Mechanics
Vahab Sarfarazi; Hadi Haeri; Mohammad Fatehi Marji; Gholamreza Saeedi; Amir Namdarmanesh
Abstract
In this paper, the effect of variations in the number and area of the rock bridges on the non-persistent discontinuities is investigated. In this regard, blocks containing rock bridges and joints with dimensions of 15 cm * 15 cm * 15 cm are prepared from plaster. The available rock bridges that have ...
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In this paper, the effect of variations in the number and area of the rock bridges on the non-persistent discontinuities is investigated. In this regard, blocks containing rock bridges and joints with dimensions of 15 cm * 15 cm * 15 cm are prepared from plaster. The available rock bridges that have occupied 0.2, 0.4, and 0.6 of the shear surface show latitudinal extension along the shear surface. There are variations in the number and extension of the rock bridges in the fixed area. For each of the samples, tests are performed on three blocks of the same material, by putting it under various direct normal stresses. Normal stresses were 3.33, 5.55, 7.77 kg/cm2. Also the obtained shear strength by laboratory tests was compared with the outputs of Jenning's criterion and Guo and Qi's criterion to determine the accuracy of these criteria for predicting the shear strength of non-persistent joints. The results show that the tensile crack started in the rock bridge under normal stress of 3.33 kg/cm2. Mixed-mode tensile shear cracks were propagated in the rock bridge under a normal stress of 5.55 kg/cm2, while a pure shear crack developed in the rock bridge under a normal stress of 7.77 kg/cm2. With the increase of normal stress, the number of microfractures increased. The variance in the number of rock bridges in the fixed area of the rock bridge does not affect the friction angle along the shear surface. Furthermore, the cohesion along the shear surface shows a small decrease with the increasing number of rock bridges. Also by the increase in the area of rock bridges, the friction angle along the shear surface remains constant, while at the same time, there is an almost linear increase in cohesion. Guo and Qi's criterion predicts the shear strength of the non-persistent joint exactly close to the shear strength of the physical samples.
Exploitation
Hamid Saberi; Mohammad Golmohammadi; Mohammadali Zanjani; Yaghoub Saberi
Abstract
The Bavanapadu-Nuvvalarevu coastal sector in Andhra Pradesh, India, hosts substantial subsurface heavy mineral (HM) resources, presenting significant economic potential. This study employs ArcGIS raster techniques to estimate Total Heavy Mineral (THM) and Total Economic Heavy Mineral (TEHM) resources ...
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The Bavanapadu-Nuvvalarevu coastal sector in Andhra Pradesh, India, hosts substantial subsurface heavy mineral (HM) resources, presenting significant economic potential. This study employs ArcGIS raster techniques to estimate Total Heavy Mineral (THM) and Total Economic Heavy Mineral (TEHM) resources in a 39 square kilometers area, integrating geospatial analysis with field data from core sediment samples. The findings reveal a total of 2.681953 million tons of THM, including 2.434422 million tons of TEHM, with the highest concentration observed in the top 1-meter sea bed sediment layer (1.605286 million tons). Ilmenite, garnet, and sillimanite dominate the mineral assemblage, accompanied by smaller quantities of zircon, monazite, and rutile, offering an estimated revenue potential of $634 to $851 million USD. The application of ArcGIS methodologies, particularly inverse distance weighting (IDW) interpolation, enabled precise mapping of HM distribution, despite challenges such as wide sample spacing and shallow core penetration. While the study highlights the economic and industrial significance of the Bavanapadu sector, it also underscores environmental concerns, including habitat disruption and sediment degradation, associated with mining. Sustainable practices, such as advanced separation technologies, site rehabilitation, and comprehensive environmental impact assessments (EIAs), are essential to mitigate ecological impacts. This research demonstrates the efficacy of GIS-based techniques in resource estimation and sustainable mining, offering a replicable framework for coastal and offshore mineral resource management globally. The findings provide critical insights into balancing economic growth with environmental preservation, setting a benchmark for responsible heavy mineral extraction in dynamic coastal environments.
Rock Mechanics
Masoud Yazdani; Mohammad Fatehi Marji; Hamid Soltanian; Mehdi Najafi; Manouchehr Sanei
Abstract
Approximately 70% of the world's hydrocarbon fields are located in reservoirs with low-strength rocks such as sandstone. During the production of hydrocarbons from sandstone reservoirs, sand-sized particles may become dislodged from the formation, and enter the hydrocarbon fluid flow. Sand production ...
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Approximately 70% of the world's hydrocarbon fields are located in reservoirs with low-strength rocks such as sandstone. During the production of hydrocarbons from sandstone reservoirs, sand-sized particles may become dislodged from the formation, and enter the hydrocarbon fluid flow. Sand production is a significant issue in the oil industry due to its potential to cause erosion of pipes and valves. Separating grains from oil is a costly process. Therefore, oil and gas-producing companies are motivated to reduce sand production during petroleum extraction. Various methods exist for predicting this phenomenon including continuous, discontinuous, experimental, physical, analytical, and numerical methods. Given the significance of the subject, this research work aims to achieve two primary objectives. Firstly, it proposes a two-dimensional numerical model based on the discrete element method to address the issues of high strain and deformation in granular materials. This method is highly reliable in simulating the mechanism of sand production in oil wells. Secondly, the production of sand is influenced by two factors: fluid pressure and stress; to evaluate changes in production from a particular reservoir, it is necessary to analyze each parameter. Two sandstone samples, similar to reservoir rock conditions, were prepared and tested in the laboratory to demonstrate sand production phenomenon. The numerical results have been verified and compared to their experimental counterparts.
Environment
Reyhaneh Khashtabeh; Morteza Akbari; Ava Heidari; Ali Asghar Najafpour; Rokhsareh Khashtabeh
Abstract
The Heavy Metal (HM) contamination in surface soils poses significant environmental and health concerns near the mining operations. This study examined the concentrations and health risks of the five HMs lead (Pb), nickel (Ni), copper (Cu), arsenic (As), and iron (Fe) in soils surrounding the Sangan ...
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The Heavy Metal (HM) contamination in surface soils poses significant environmental and health concerns near the mining operations. This study examined the concentrations and health risks of the five HMs lead (Pb), nickel (Ni), copper (Cu), arsenic (As), and iron (Fe) in soils surrounding the Sangan iron ore mines in eastern Iran. Sixty soil samples were collected at depths of 0-20 cm from sites adjacent to the mining area and one control site. The HM concentrations were compared to the global shale values. Soil contamination was quantified using the geo-accumulation index (Igeo). Health risks to the local residents were assessed using the US Environmental Protection Agency's Human Health Risk Evaluation Index. The analysis revealed that the lead concentrations near the mine exceeded the global shale standards, while the arsenic levels remained marginally below permissible limits established by global soil standards. The Igeo values indicated low to moderate the contamination levels for both Pb and As in the mining-adjacent areas. The risk assessment results showed that non-carcinogenic risk indices were within acceptable limits for both children and adults. However, arsenic posed a significant carcinogenic risk to adults through two exposure pathways: ingestion (3.36E-04) and dermal absorption (1.36E-04). These findings highlight the importance of implementing regular monitoring protocols for potentially hazardous elements in the mining region to prevent and mitigate pollution-related health risks.
