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.
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.
Exploitation
S. Safari Sinegani; M. Ziaii; M. Ghoorchi; M. Sadeghi
Abstract
In this work, the concentration gradient (CG) analysis of local-scale exploration for Porphyry-Cu deposits is applied in two zones using the G(Vz) index (CG(Zn*Pb)/CG(Cu*Mo)). The first zone is covered by a 1:2000 map of the Sungun and Astamal areas in NW Iran and the second one in the Inza area in British ...
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In this work, the concentration gradient (CG) analysis of local-scale exploration for Porphyry-Cu deposits is applied in two zones using the G(Vz) index (CG(Zn*Pb)/CG(Cu*Mo)). The first zone is covered by a 1:2000 map of the Sungun and Astamal areas in NW Iran and the second one in the Inza area in British Columbia, Canada. The rock samples are taken from Sungun and Astamal and the soil samples are taken from Inza. The Inza samples are analyzed for Cu, Pb, Zn, and Mo elements by the atomic absorption method, while the rock samples of Astamal and Sungun are analyzed for Cu, Pb, Zn, Mo, Ag, As, and Sb elements. The indices of gradient geochemical zonality (G(Vz)) of multi-elements around the mineral deposits and their spatial associations with particular geological, geochemical, and structural factors are the critical aspects that must be considered in mineral exploration. The values for the G(Vz) indices allow a distinction between the sub-ore and supra-ore anomalies, which are associated with Zone Dispersed Mineralization (ZDM) and Blind Mineralization (BM), respectively. For a comparative identification of BM and ZDM, a supra-ore (Pb*Zn) anomaly, a sub-ore (Cu*Mo) anomaly, and Vz maps are used in place of the mining geochemistry representing the supra-ore gradient anomaly, sub-ore gradient anomaly and G(Vz) map. The G(Vz) model outperforms the Vz model. The introduced technique allows for a computational distinction between the BM and ZDM ore mineralizations without exploration drilling. Prior to writing this paper, the blind porphyry-Cu mineralization was intersected at depth through borehole exploration in a highly prospective zone delineated by the G(Vz) model. The results obtained confirm the usefulness of the G(Vz) modeling for local-scale targeting of blind mineral deposits.
Seyed M. Pourhashemi; K. Ahangari; J. Hassanpour; Seyed M. Eftekhari
Abstract
Mechanized tunneling in rocks is based on fracture propagation and rock fragmentation under disc cutters. Rock chipping is an efficient kind of fragmentation process, while the grinding process may occur under special conditions. The cutter-head penetration is an appropriate parameter involved in order ...
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Mechanized tunneling in rocks is based on fracture propagation and rock fragmentation under disc cutters. Rock chipping is an efficient kind of fragmentation process, while the grinding process may occur under special conditions. The cutter-head penetration is an appropriate parameter involved in order to distinguish between the chipping and grinding processes in rock cutting. In this work, the grinding and chipping processes are investigated in the Uma-Oya water conveyance tunnel in Sri Lanka. The Uma-Oya project is a water transfer, hydropower, and irrigation system in the SE part of the central highland region of Sri-Lanka. From a geological viewpoint, most parts of the tunnel route in the studied section consist of very strong and abrasive metamorphic rocks that potentially are susceptible to grinding occurrence during the boring process under disc cutters. In this work, firstly, data processing is performed in order to identify the boundary between chipping and grinding. Then the chipping and grinding processes are modeled using the practical numerical and artificial intelligent methods. In the numerical modeling stage, we try to make the modeling as realistic as possible. The results obtained from these modeling methods show that for the penetrations less than 3 mm/rev, the grinding process is dominant, and for the penetrations more than 3 mm/rev, rock chipping occurs. Also, in the numerical modeling, no significant fracture expansion is observed in the rock when the penetration is less than 3 mm/rev. Moreover, it can be seen in the numerical modeling of the chipping process that the propagated fractures come together and the chips are created.
Rock Mechanics
S. Moshrefi; K. Shahriar; A. Ramezanzadeh; K. Goshtasbi
Abstract
A new failure criterion was presented to predict the ultimate strength of shale under the triaxial and polyaxial state of stress. A database containing 93 datasets was obtained from the results of the uniaxial, triaxial, polyaxial compressive tests, an indirect tensile test was collected from reliable ...
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A new failure criterion was presented to predict the ultimate strength of shale under the triaxial and polyaxial state of stress. A database containing 93 datasets was obtained from the results of the uniaxial, triaxial, polyaxial compressive tests, an indirect tensile test was collected from reliable references, and this test was carried out on the shale samples taken from the southwestern oilfields in Iran. The database was used to evaluate the proposed criterion, and its accuracy was compared against the popular failure criteria in rock mechanics, particularly those used for stability analysis such as the Hoek-Brown, Mohr-Coulomb, Drucker-Prager, and Mogi-Coulomb failure criteria. In order to evaluate the model, seven important statistical indices were selected. Subsequently, curves from various failure criteria were fitted to the triaxial and polyaxial data, and the corresponding coefficients and statistical indices were determined. The results obtained indicated that, in all cases, compared to the other failure criteria, the proposed criterion succeeded to predict the ultimate strength at a higher accuracy. Also the proposed criterion was used calculate the uniaxial compressive and tensile strengths with a minimum error. For a further examination of the proposed criterion, a series of results from the triaxial test including the ductile failure data were utilized for evaluation of the applicability of the proposed criterion to the ductile zone. It showed that the criterion could predict the ultimate strength of shale over a wide range of stresses.
Exploration
F. Mirsepahvand; M.R. Jafari; P. Afzal; M. A. Arian
Abstract
The goal of this research work is to recognize the metallic mineralization potential in the Ahar 1:100,000 sheet (NW Iran) using the remote sensing data based on determination of the alteration zones. This area is located in the Ahar-Arasbaran metallogenic zone as a significant metallogenic zone in Iran ...
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The goal of this research work is to recognize the metallic mineralization potential in the Ahar 1:100,000 sheet (NW Iran) using the remote sensing data based on determination of the alteration zones. This area is located in the Ahar-Arasbaran metallogenic zone as a significant metallogenic zone in Iran and Caucasus. In this research work, the Landsat-7 ETM+ and advanced space borne thermal emission and reflection radiometer (ASTER) multispectral remote sensing data was interpreted by the least square fit (LS-Fit), spectral angle mapper (SAM), and matched filtering (MF) algorithms in order to detect the alteration zones associated with the metallic mineralization. The results obtained by these methods show that there are index-altered minerals for the argillic, silicification, advanced argillic, propylitic, and phyllic alteration zones. The main altered areas are situated in the SE, NE, and central parts of this region.
Exploitation
A. Saffari; M. Ataei; F. Sereshki
Abstract
Spontaneous combustion of coal is one of the most horrifying hazards in coal industries, especially in underground coal mines. Thus having a prior knowledge about the occurrence of this phenomenon in underground coal mines is of crucial importance in preventing this process, loss of life, huge economic ...
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Spontaneous combustion of coal is one of the most horrifying hazards in coal industries, especially in underground coal mines. Thus having a prior knowledge about the occurrence of this phenomenon in underground coal mines is of crucial importance in preventing this process, loss of life, huge economic loss, and environmental pollution. The aim of this work is to determine the spontaneous combustion of coal potential in the Tabas Parvadeh coal mines in Iran in order to assess the effect of coal intrinsic characteristics on its occurrence. For the purpose of this investigation, the coal samples were collected from Parvadeh I to IV, and the coal intrinsic characteristics of the samples were tested. In order to determine the spontaneous combustion of coal propensity in this case study, the Crossing Point Temperature (CPT) test was used. Then the relation between the coal intrinsic characteristics and the CPT test values was determined. The results obtained showed that the B1 seam in Parvadeh II and C1 seam in Parvadeh III had a high potential of spontaneous combustion of coal potential. These results also show that an increase in the moisture, volatile matter, pyrite, vitrinite, and liptinite contents enhance the spontaneous combustion of coal tendency in these mines. The results obtained have major outcomes for the management of this phenomenon in the Tabas Parvadeh coal mines. Therefore, evaluation of the spontaneous combustion of coal hazards in coal mines should start in the first stage of design and carried on during their whole lifecycle, even after mine closure.
Hassan Sarfaraz; Mohadeseh Sarlak; Fatemeh Ashoor; Erfan Amini
Abstract
In rock slopes, block toppling failure is a prevalent instability. In this instability, rock mass consists of a series of dominant parallel discontinuities that are dipping steeply into the slope face, and a series of cross-joints are located normal to the dominant discontinuities. Blocks may slide or ...
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In rock slopes, block toppling failure is a prevalent instability. In this instability, rock mass consists of a series of dominant parallel discontinuities that are dipping steeply into the slope face, and a series of cross-joints are located normal to the dominant discontinuities. Blocks may slide or rotate due to their weight along the natural cross-joints at their base, and the tensile strength does not significantly affect the stability of the rock slope. The rounding edge of rock columns is a special feature of spheroidal weathering. Firstly, a literature review of block toppling instability is presented. Next, applying the Sarma approach, a new theoretical analysis is proposed for the rock columns with rounded edges. One of the advantages of the proposed approach is that by determining the sign of a parameter called KC, the stability status can be specified. The suggested solution is compared with a pre-existing analytical method through examples and case study. Comparisons indicate that the proposed approach has a satisfactory agreement. It can be concluded that with weathering and rounding of the block edges, the safety factor decreases non-linearly. Therefore, this solution can be used to evaluate the blocky toppling failure regarding the erosion phenomenon.
Exploitation
Emad Ansari; Ramin Rafiee; Mohammad Ataei
Abstract
Due to longwall mining, a large space without any support is created, and the in-situ stress regimes change. The change of the in-situ stress regimes affects the roof and face of the adjacent panel. In other words, the strata behavior would be different from the intact condition during the previous panel ...
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Due to longwall mining, a large space without any support is created, and the in-situ stress regimes change. The change of the in-situ stress regimes affects the roof and face of the adjacent panel. In other words, the strata behavior would be different from the intact condition during the previous panel mining. In this study, two adjacent panels are simulated in the FLAC3D software to study the effect of panel extraction on its adjacent panel strata behavior during longwall mining. The available data of the Tabas Parvadeh Coal Mine panels is used for this purpose. According to the numerical modeling results, the length of the first roof’s weighting effect (FRWE) in the gob of the first and second panels is calculated, respectively, as 26 and 21 meters. In other words, the gob dimension in the second panel is reduced by about 19.2%, and the vertical displacement value is increased by about 18.5%. In addition, the chance of roof collapse and face spalling during the first-panel mining is more than the second-panel. It means that roof and face instability in the (FRWE) during the first-panel mining is confirmed, while in the second-panel extraction is just very likely.
Exploitation
M. M. Tahernejad; M. Ataei; R. Khalokakaie
Abstract
In the context of open-pit mine planning, uncertainties including commodity price would significantly affect the technical and financial aspects of mining projects. A mine planning that takes place regardless of the uncertainty in price just develops an optimized plan at the starting time of the mining ...
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In the context of open-pit mine planning, uncertainties including commodity price would significantly affect the technical and financial aspects of mining projects. A mine planning that takes place regardless of the uncertainty in price just develops an optimized plan at the starting time of the mining operation. Given the price change over the life of mine, which is quite certain, optimality of the proposed plan will be eliminated. This paper presents a risk-averse decision-making tool to help mine planners in mining activities under price uncertainty. The objective is to propose mine planning in a way that a target Net Present Value (NPV) is guaranteed. In order to reach this goal, Information Gap Decision Theory (IGDT) is developed to hedge the mining project against the risk imposed by the information gap between the forecasted and actual price. The proposed approach is of low sensitivity to the price change over the life of mine, and can use the estimated prices with uncertainty. A case study at an existing iron mine demonstrates the performance of the proposed approach. The results obtained showed that the proposed method could provide a robust solution to mine planning under price uncertainty. Moreover, it was concluded that the method could present more reliable mine plans under condition of price uncertainty.
Rock Mechanics
A.R. Dormishi; M. Ataei; R. Khaloo Kakaie; R. Mikaeil; S. Shaffiee Haghshenas
Abstract
One of the most significant and effective criteria in the process of cutting dimensional rocks using the gang saw is the maximum energy consumption rate of the machine, and its accurate prediction and estimation can help designers and owners of this industry to achieve an optimal and economic process. ...
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One of the most significant and effective criteria in the process of cutting dimensional rocks using the gang saw is the maximum energy consumption rate of the machine, and its accurate prediction and estimation can help designers and owners of this industry to achieve an optimal and economic process. In the present research work, it is attempted to study and provide models for predicting the maximum energy consumption of the gang saw during the process of soft dimensional rocks with the help of an intelligent optimization model such as random non-linear techniques, i.e. the Hybrid ANFIS-DE and Hybrid ANFIS-PSO algorithms based upon 4 physical and mechanical parameters including uniaxial compressive strength, Mohs hardness, Schimazek’s F-abrasiveness factors, Young modulus, and an operational characteristic of the machine, i.e. production rate. During this research work, 120 samples are tested on 12 carbonate rocks. The maximum energy consumption of the cutting machine during this work is measured and used as a modeling output for evaluating the performance of cutting machine. Also meta-heuristic algorithms including DE and PSO algorithms are used for training the Adaptive Neural Fuzzy Inference System (ANFIS). In addition, the PSO algorithm has a higher ability in terms of model output and performance indices and has a superiority over the differential evolution algorithm. Furthermore, comparison between the measured datasets with the ANFIS-DE and ANFIS-PSO models indicate the accuracy and ability of the ANFIS-PSO model in predicting the performance of gang saw considering the machine’s properties and the cut rock.
V. Maazallahi; A. Majdi
Abstract
The uniaxial compressive strength (UCS) of intact rocks is one of the key parameters in the course of site characterizations. The isotropy/anisotropy condition of the UCS of intact rocks is dependent on the internal structure of the rocks. The rocks with a random grain structure exhibit an isotropic ...
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The uniaxial compressive strength (UCS) of intact rocks is one of the key parameters in the course of site characterizations. The isotropy/anisotropy condition of the UCS of intact rocks is dependent on the internal structure of the rocks. The rocks with a random grain structure exhibit an isotropic behavior. However, the rocks with a linear/planar grain structure generally behave transversely-isotropic. In the latter case, the UCS of intact rocks must be determined by a set of laboratory tests on the oriented rock samples. There are some empirical relations available to describe the strength of these rocks. Though characterization of transversely-isotropic rocks is practically a 3D problem, but these relations provide only a 2D description. In this paper, a method is proposed to provide a 3D description of UCS of transversely-isotropic rocks. By means of this formulation, one can determine UCS along with any arbitrary spatial direction. Also, a representative illustration of UCS is proposed in the form of contour-plots on a lower hemisphere Stereonet. The method is applied to an actual case study from the Kanigoizhan dam site located in the Kurdistan Province (Iran). Application of the proposed method to the phyllite rocks of this site show that the direction perpendicular to the dam axis exhibits the most anisotropic behavior. Hence, it is essential to take the strength anisotropy into account during the relevant analysis. The results obtained, together with the statistical variation of UCS, provide a practical approach to select the proper values of UCS according to the scope of the analysis.
Enayatallah Emami Meybodi; Fatemeh Taajobian
Abstract
Due to the challenge of finding identical rock samples with varying grain sizes, investigating the impact of texture on rock material has been given less attention. However, macroscopic properties such as compressive strength, tensile strength, and modulus of elasticity can indicate microscopic properties ...
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Due to the challenge of finding identical rock samples with varying grain sizes, investigating the impact of texture on rock material has been given less attention. However, macroscopic properties such as compressive strength, tensile strength, and modulus of elasticity can indicate microscopic properties like intergranular resistance properties influence rock fracture toughness. In this work, both the experimental and numerical methods are used to examine the effect of grain size on the mechanical properties of sandstone. Uniaxial compressive strength and indirect tensile tests are conducted on sandstone samples with varying grain sizes, and the particle flow code software is used to model the impact of grain dimensions on intergranular properties. Flat joint model is applied for numerical modeling in the particle flow code© software. The aim of this work is to validate the numerical model by peak strength failure and stress-strain curves to determine the effect of grain size on the mechanical behavior. The results show that increasing grain size significantly decrease compressive strength, tensile strength, and modulus of elasticity. The impact of the change in grain size is more significant on compressive strength than on the other two properties. The correlation coefficient for tensile strength and grain size is R2 = 0.57, while for modulus of elasticity and grain size, it is R2 = 0.79. The PFC software helps calibrate intergranular properties, and investigate the effect of changing grain size on these properties. Overall, this study offers valuable insights into the relationship between the grain size and the mechanical properties of sandstone, which can be useful in various engineering applications, especially in petroleum geo-mechanics.
Exploration
Bashir Shokouh Saljoughi; Ardeshir Hezarkhani
Abstract
The porphyry Cu-mineralization potential area studied in this article is located in the southern section of the Central Iranian volcano–sedimentary complex, contains large number of mineral deposits, and occurrences that are currently facing a shortage of resources. Therefore, prospecting potential ...
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The porphyry Cu-mineralization potential area studied in this article is located in the southern section of the Central Iranian volcano–sedimentary complex, contains large number of mineral deposits, and occurrences that are currently facing a shortage of resources. Therefore, prospecting potential areas in the deeper and peripheral spaces has become a high priority in this region. Different direct and indirect methods try to predict promising areas for future explorations that most of them are very time-consuming and costly. The main goal of mineral prospecting is applying a transparent and robust approach for identifying high potential areas to be explored further in the future. This study presents the procedure taken to create two different Cu-mineralization prospectivity maps. This study aims to investigate the results of applying the ANN technique, and to compare them with the outputs of applying GEP method. The geo-datasets employed for creating evidential maps of porphyry Cu mineralization include solid geology map, alteration map, faults, dykes, airborne total magnetic intensity, airborne gamma-ray spectrometry data (U, Th, K and total count), and known Cu occurrences. Based on this study, the ANN technique (10 neurons in the hidden layer and LM learning algorithm) is a better predictor of Cu mineralization compared to the GEP method. The results obtained from the P-A plot showed that the ANN model indicates that 80% (vs. 70% for GEP) of the identified copper occurrences are projected to be present in only 20% (vs. 30% for GEP) of the surveyed area. The ANN technique due to capabilities such as classification, pattern matching, optimization, and prediction is useful in identifying anomalies associated with the Cu mineralization.
Mineral Processing
A. Abbasi Gharaei; B. Rezai; H. Hamidian Shoormasti
Abstract
According to the classification of the nickel laterite, this paper describes mineralogy test is to reveal where valuable elements are located in the ore, in which mineralogical form. The purpose of the sieving test was to study if some specific particle size contains most of the valuable metals. Based ...
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According to the classification of the nickel laterite, this paper describes mineralogy test is to reveal where valuable elements are located in the ore, in which mineralogical form. The purpose of the sieving test was to study if some specific particle size contains most of the valuable metals. Based on its chemical composition nickel laterite is classified as a limonite type and the nickel and cobalt content was 0.7 and 0.04%, respectively. Nickel is predominantly associated with hematite and goethite. Based on the mineralogical analysis of the ore, it is observed that remarkable part of nickel is located in hematite. Therefore, nickel cannot be released from hematite lattice. The nickel content in the laterite was 0.7% and the cobalt content 0.04%. The chemical composition of laterite equals with the occurrence of 38.9% iron oxides, 26.9% carbonates, 26.9% quartz, 4.8% chromite, 2.7% magnetite and 1.9% other minerals. EDS line profile analyses were completed on hematite/goethite ooids and there was a slight correlation in the quantities between iron and nickel in each individual ooid. However, iron and nickel do not always show a positive correlation. Nickel grade could be enriched from 0.7 wt.-percent to 0.91 wt.-percent; however nickel recovery was only 45%.
M. Hosseini; D. Fakhri
Abstract
The purpose of this work is to investigate the possibility of using mine wastes in the improvement of concrete properties. This research work investigates the physical and mechanical properties of the concrete specimens. These concrete specimens include concrete-lacking fibres, micro-silica and limestone ...
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The purpose of this work is to investigate the possibility of using mine wastes in the improvement of concrete properties. This research work investigates the physical and mechanical properties of the concrete specimens. These concrete specimens include concrete-lacking fibres, micro-silica and limestone powder (C), concrete-containing glass fibres without micro-silica and limestone powder (GC), concrete-containing micro-silica and limestone powder without fibres (CML), and concrete-containing glass fibres, micro-silica, and limestone powder (CGML). The physical and mechanical properties including the effective porosity, longitudinal wave velocity, water absorption, unit weight, tensile strength, uniaxial compressive strength, triaxial compressive strength, cohesion, and internal friction angle are investigated. The results obtained show that adding glass fibres to the concrete (GC) improve its properties compared to the fibre-less concrete (C). However, the properties of GC are improved significantly less than CGML. The Brazilian tensile strength and uniaxial compressive strength of GC increase by 13.6% and 10.95% relative to C. The Brazilian tensile strength and uniaxial compressive strength of CGML increase by 21.8% and 45.94% relative to C. Finally, it can be concluded that adding the micro-silica and limestone powder to the glass fibre concrete as well as the use of mine wastes also significantly improves the properties of the concrete.
M. Mohammadkhani; M. Abdollahy; M. R. Khalesi
Abstract
Copper oxide minerals such as malachite do not respond well to the traditional copper sulfide collectors, and require alternative flotation schemes. In many copper ore mines, significant copper oxide minerals, especially malachite, are associated with sulfide minerals. Considering that xanthates are ...
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Copper oxide minerals such as malachite do not respond well to the traditional copper sulfide collectors, and require alternative flotation schemes. In many copper ore mines, significant copper oxide minerals, especially malachite, are associated with sulfide minerals. Considering that xanthates are most widely used in the flotation of sulfide minerals as well as copper sulfide minerals and, hydroxamate has shown a good selectivity for copper oxide minerals. Use of the synergistic effect of xanthate and hydroxamate can be an effective way to increase the flotation efficiency of copper oxide minerals along with sulfide minerals. In this work, we investigate the individual interactions of potassium amyl xanthate (PAX) and potassium alkyl hydroxamate (HXM) with the natural malachite and explore their synergistic effects on the malachite flotation. The results of solubility of malachite in collector solutions, changes in the malachite surface potential, adsorption kinetics, adsorption densities, dynamic contact angles, FT-IR analyses, and small-scale flotations, are discussed. The results obtained demonstrate that PAX and HXM are chemically co-adsorbed on the malachite surface, and the amount of PAX adsorbed on the malachite surface is considerably increased in the mixed PAX/HXM systems because of the co-adsorption mechanism. The flotation results confirm that the mixed PAX/HXM exhibit a superior flotation performance of malachite compared to the individual system of PAX or HXM. Based on these results, the mixed PAX/HXM exhibit a remarkable synergism effect on malachite surface hydrophobicity.
Exploration
Hossein Mahdiyanfar; Mirmahdi Seyedrahimi-Niaraq
Abstract
The primary purpose of this investigation is contamination mapping in surrounding areas of Irankuh Pb–Zn mine, located in central Iran, using an integrated approach of principal component analysis (PCA) with the Concentration-Area (C-A) and Power Spectrum-Area (S-A) fractal models. PCA categorized ...
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The primary purpose of this investigation is contamination mapping in surrounding areas of Irankuh Pb–Zn mine, located in central Iran, using an integrated approach of principal component analysis (PCA) with the Concentration-Area (C-A) and Power Spectrum-Area (S-A) fractal models. PCA categorized the 45 elements into eight principal components. Component 2, containing the toxic elements of Pb, Zn, As, Mn, Cd, and Ba, was identified as the contamination factor. This multivariate contamination factor was modeled using the C-A and S-A fractal methods (in spatial and frequency domains) to delineate pollution areas. Modeling of PCA data using the C-A fractal method showed four main populations for the contamination factors. Two populations with higher fractal dimensions are associated with contamination from mining activities or anthropogenic effects. Low fractal dimensions are considered the background population, which has not been affected or is less affected by these activities. Five geo-chemical populations were obtained for contamination factors using the S-A fractal modeling of PCA in the frequency domain. Therefore, various geo-chemical populations were achieved using geo-chemical filtering and two-dimensional inverse Fourier transformation. The geo-chemical populations related to classes 2, 3, and 4 containing intermediate frequency signals showed the pollution anomaly. The spatial distribution of pollutant geo-chemical signals exhibits excellent conformity with the mining operation limit and tailing dam location as pollutant sources. The results indicate that the elements Pb, Zn, Cd, and As have significant values in the surrounding soils rather than their concentrations in the earth’s crust. The results demonstrate that the S-A fractal models can more precisely delineate the environmental anomaly than the C-A fractal model, especially in intermediate frequency populations.
R. Dabiri; E. Amiri Shiraz
Abstract
This paper describes a preliminary study of the adsorption of toxic elements from synthetic wastewater in a batch mode. Clay minerals have been highly considered as inexpensive available adsorbents that adapt with the environment due to a special level and a high potential of adsorption. In the present ...
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This paper describes a preliminary study of the adsorption of toxic elements from synthetic wastewater in a batch mode. Clay minerals have been highly considered as inexpensive available adsorbents that adapt with the environment due to a special level and a high potential of adsorption. In the present research work, low-cost natural minerals of speiolite from the Iliato mine (located in NE Iran) and zeolite from the Aftar mine (located in north of Iran) are used to remove nickel(II), antimony(III), and arsenic(V) from synthetic wastewater. The adsorption experiments are conducted by varying the initial concentrations of the elements, pH values, adsorption times, and adsorbent dosage. The experimental isotherm data is analyzed using the Langmuir and Freundlich equations. Concerning a higher Langmuir coefficient R2 in nickel and antimony, the mechanism of adsorption of these elements is mono-layer and homogenous. Based on the Freundlich model, adsorption of arsenic is multi-layer and heterogeneous. The kinetic studies show that the Ni, Sb, and As adsorption mechanism is well-described by a pseudo-second-order kinetic model. The thermodynamic parameters indicate that the adsorption process has an exothermic character and is more feasible with decreasing temperature. Based on the experimental results, it can be concluded that natural sepiolite and zeolite has the potential of application as an efficient adsorbent for the removal of toxic elements from synthetic wastewater.
Rock Mechanics
M. Lotfi; B. Tokhmechi
Abstract
Nowadays, Barton’s Joint Roughness Coefficients (JRC) are widely used as the index for roughness and as a challenging fracture property. When JRC ranking is the goal, deriving JRC from different fractal/wavelet procedures can be conflicting. Complexity increases when various rankings outcome from ...
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Nowadays, Barton’s Joint Roughness Coefficients (JRC) are widely used as the index for roughness and as a challenging fracture property. When JRC ranking is the goal, deriving JRC from different fractal/wavelet procedures can be conflicting. Complexity increases when various rankings outcome from different calculation methods. Therefore, using Barton’s JRC, we cannot make a decision based on the proven mathematical theories because each method has a different rank. Ideally, these rankings must be equal but, in practice, they are different for each method. To solve this problem and to achieve a robust and valid ranking for JRC, Condorcetand Borda count methods have been used. These methods have been proposed as fusion approaches. Re-ranking of JRC using different methods integrated with Condorcet showed confusion in ranking of the JRC4, JRC5, and JRC6 profiles. This ambiguity is equal to equalizing decision conditions about all the three at the examination of the winners, losers, and draws in pairwise matrices. Therefore, Borda Count was applied and resulted in robust rankings. In fact, a new approach for a roughness measurement is presented. A new JRC ranking called JRCN is introduced. This new ranking shows a lower sum of squared errors (0.00390) in comparison with the original JRC ranking method (0.00410) and ranked JRCN1 to JRCN10. Thus it is proposed to consider JRCN as a new and improved version of JRC rankings.
Rock Mechanics
Ali Kazempour Osalou; Sayfoddin Moosazadeh; Ali Nouri Qarahasanlou; Mohammad-Reza Baghban Golpasand
Abstract
Nowadays, tunnel excavation plays a major role in the development of countries. Due to the complex and challenging ground conditions, a comprehensive study and analysis must be done before, during, and after the excavation of tunnels. Hence, the importance of study and evaluation of ground settlement ...
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Nowadays, tunnel excavation plays a major role in the development of countries. Due to the complex and challenging ground conditions, a comprehensive study and analysis must be done before, during, and after the excavation of tunnels. Hence, the importance of study and evaluation of ground settlement is dramatically increased since many tunnel projects are performed in urban areas, where there are plenty of constructions, buildings, and facilities. For this reason, the control and prediction of ground settlement is one of the complicated topics in the field of risk engineering. Therefore, in this paper, the proportional hazard model (PHM) is used to analyze and study the ground settlement induced by Tabriz Metro Line 2 (TML2) tunneling. The PHM method is a semi-parametric regression method that can enter environmental conditions or factors affecting settlement probability. These influential factors are used as risk factors in the analysis. After establishing a database for a case study and using a proportional hazard model for surface settlement analysis, and then by evaluating the effect of environmental conditions on the ground surface settlement, it has been found that the risk factors of grouting pressure behind the segment, the ratio of tunnel depth to groundwater level, and drained cohesion strength at a significant level of 5% have a direct effect on the probability of settlement. The results also showed that the effect of grout injection pressure on ground subsidence is more than other parameters, and with increasing injection pressure, the probability of exceeding safe subsidence values decreases. In addition, it has been found that increasing the risk factor for the ratio of tunnel depth to groundwater level reduces the probability of exceeding the safe ground settlement. Finally, increasing the number of risk factors for drained cohesion strength increases the probability of exceeding safe settlement.
R. Alizadeh; M. Fatehi Marji; A. Abdollahipour; M. Pourghasemi Sagand
Abstract
In this work, an effective methodology is introduced for modeling the fatigue crack propagation in linear elastic brittle media. The displacement discontinuity method is used to accomplish the analysis, and the boundaries are discretized with quadratic elements in order to predict the stress intensity ...
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In this work, an effective methodology is introduced for modeling the fatigue crack propagation in linear elastic brittle media. The displacement discontinuity method is used to accomplish the analysis, and the boundaries are discretized with quadratic elements in order to predict the stress intensity factors near the crack tips. This procedure is implemented through 2D linear elastic fracture mechanics. The normal and shear displacement discontinuity around the crack tip is applied to compute the mixed-mode stress intensity factors. The crack growth is incremental, and for each increment of extension, there is no need to use a re-meshing procedure. This method has benefits over the finite element method due to its simplicity in meshing. The crack growth direction is assessed using the maximum principal stress theory. In these analyses, a repetition method is used in order to estimate the correct path of crack propagation. Therefore, the different lengths of incremental growth do not affect the crack growth path analysis. The results are exhibited for several examples with different geometries to demonstrate the efficiency of the approach for analyzing the fatigue crack growth. The accuracy represents that this formulation is ideal for describing the fatigue crack growth problems under the mixed-mode conditions.
