Environment
Lateef Bankole Adamolekun; Taiwo Blessing Olamide; Muyideen Alade Saliu; Esma Kahraman; Victor Afolabi Jebutu; Yewuhalashet Fissha; Adams Abiodun Akinlabi
Abstract
Examining the applicability of laterite clay for landfill and other engineering applications is critical due to the daily challenges that practitioners face as a result of material property variation. The suitability of seven selected laterite deposits in southwestern Nigeria as usable liner material ...
Read More
Examining the applicability of laterite clay for landfill and other engineering applications is critical due to the daily challenges that practitioners face as a result of material property variation. The suitability of seven selected laterite deposits in southwestern Nigeria as usable liner material in solid waste landfill construction was investigated in this study, taking geotechnical properties and chemical composition into account. Purposive samples were collected and tested in accordance with ASTM standard procedures for analyzing geotechnical properties. X-ray diffraction analysis was used to determine the soil's clay mineral composition. The clay mineral composition of the soil was determined using X-ray diffraction analysis. The geotechnical analysis revealed the following ranges for the samples: gravel particle size percentage (3.7% to 34.0%), fines particle size percentage (17.4% to 71.7%), liquid limit (28.1% to 65.8%), plasticity index (3.95 to 45.53), activity (0.44 to 0.81), coefficient of permeability (6.75 x10-10 m/s to 5.80 x 10-6 m/s), specific gravity (2.639 to 2.768), and maximum dry density (1462 kg/m3 to 2065 kg/m3). X-ray diffraction test revealed that the clay minerals content in the seven location clay deposit varies depending on location. The study revealed that the clay mineralogical composition affects the suitability of the soil as a landfill liner material. Four among the seven clay deposits considered in this study were found suitable as a liner for solid waste landfills as compared with landfill material standard specifications.
Sajjad Aghababaei; Hossein Jalalifar; Ali Hosseini; Farhad Chinaei; Mehdi Najafi
Abstract
In this work, two rock engineering system (RES)-based models are presented, the first model to predict the roof failure when a longwall face advances toward a pre-driven recovery room (PDRR) and the second model to select the type of recovery room method for longwall mining. For the first model, an international ...
Read More
In this work, two rock engineering system (RES)-based models are presented, the first model to predict the roof failure when a longwall face advances toward a pre-driven recovery room (PDRR) and the second model to select the type of recovery room method for longwall mining. For the first model, an international database of 43 case histories from the pre-driven rooms including technical parameters and type of corresponding operation outcome of each case history is considered. In this regard, a vulnerability index (VI) that refers to the risk of roof failure is calculated for each case history and the VIs are compared with the type of the corresponding outcomes. The obtained results indicate that the calculated VIs have a good adaptation with the corresponding outcomes. This approach could be used to analyze the risk of failure in PDRR, and determine the critical VI that specifies the boundary between the hazard range and the safe range that leads to an accurate operational planning. In the following, a method called multi-options RES-based model (MORESM) is adopted for the selection of recovery room methods in longwall operation. By this model, selecting the optimum option from several options in terms of many effective parameters on the system is possible. Based on the evaluations, CRR, PDRR3, and PDRR2&3 are the suitable options for the case study. This model could introduce the suitable option based on geotechnical conditions but the final decision depends on the economic policy of the managing team.
H. Amani; H. Naderi
Abstract
Gallium extraction from Jajarm Bayer process liquor (Jajarm, Iran) was investigated using microemulsions. Also the behavior of aluminum was studied as an impurity. Kelex100 (4-ethyl, 1-methyl, 7-octyl, 8-hydroxyquinoleine), iso-decanol and n-butanol, and kerosene were used as the surfactant, co-surfactant, ...
Read More
Gallium extraction from Jajarm Bayer process liquor (Jajarm, Iran) was investigated using microemulsions. Also the behavior of aluminum was studied as an impurity. Kelex100 (4-ethyl, 1-methyl, 7-octyl, 8-hydroxyquinoleine), iso-decanol and n-butanol, and kerosene were used as the surfactant, co-surfactant, and oil phase, respectively. Ternary phase diagrams were produced using various co-surfactants at different C/S ratios. The results obtained show that Winsor II is the predominant region, and the least area was obtained using iso-decanol at C/S = 4. Using n-butanol or iso-decanol at C/S = 2, 100% of gallium was extracted. The equations of the statistical models for the gallium and aluminum extractions using different co-surfactants were calculated. While the highest gallium extraction (100%) was obtained using n-butanol, due to the high co-extraction of aluminum, the lowest separation and enrichment factors were obtained for this system. The highest separation and enrichment factors were obtained using iso-decanol at C/S = 2. The point with the compositions of XAF = 30, XOF = 20, and XC/S = 50 was found to be a suitable choice, and led to 74% and 14% extractions for gallium and aluminum, respectively. An enrichment factor of 5.28 was obtained.
S. Torbati; S. Alipour; M. Rostami; S. Hajializadeh
Abstract
The Agh-Dareh and Zarshouran mines are two known active gold deposits in Takab, NW Iran. In the present study, the potentials of two species of Astragalus (A. microcephalus from Agh-Dareh and A. effusus from Zarshouran mines), as the dominant plants grown in these areas, were assessed for the bio-accumulation ...
Read More
The Agh-Dareh and Zarshouran mines are two known active gold deposits in Takab, NW Iran. In the present study, the potentials of two species of Astragalus (A. microcephalus from Agh-Dareh and A. effusus from Zarshouran mines), as the dominant plants grown in these areas, were assessed for the bio-accumulation of the major, trace, and rare earth elements (REEs). The plant and soil samples were collected from the mining areas and analyzed by inductively coupled plasma-mass spectroscopy (ICP-MS). According to the results obtained, A. effusus in the Zarshouran mine passed a high ability in the accumulation of some major elements such as S, P, K, Ca, and Zn. Although the amounts of the examined trace elements in the soil samples were more than those in the shoots of both examined plants, the potential of A. microcephalus in the absorbance and translocation of Cd, U, Tl, and Pb was more than that for A. effusus. It became clear that the performance of A. microcephalus from the Agh-Dareh mine in the uptake and transportation of REEs was more than that for A. effusus from the Zarshouran mine; also both plant species absorbed and transported much more light REEs than heavy REEs did. According to the results obtained, the present study provides some geochemical findings about the substrate and leads to the increasing information about the plants as a useful indicator of metal mineralization.
Mineral Processing
M. Noori; R. Dehghan
Abstract
In the Tabas coal preparation plant (SE Iran), -50 + 6 mm raw coal was treated in a 700 mm two-stage two-density Tri-Flo dynamic dense medium separator. In order to study the circuit performance and to evaluate the separator efficiency, 32 mm cubic density tracers were used in the range of 1.28-2.1 g/cm3 ...
Read More
In the Tabas coal preparation plant (SE Iran), -50 + 6 mm raw coal was treated in a 700 mm two-stage two-density Tri-Flo dynamic dense medium separator. In order to study the circuit performance and to evaluate the separator efficiency, 32 mm cubic density tracers were used in the range of 1.28-2.1 g/cm3 and under different operational conditions. The performance of Tri-Flo was evaluated in a rapid manner, and an acceptable partitioning performance was observed under the process regime; the misplacements were in the normal range. Contrary to the dense media cyclones where the cut point shift (CPS) is usually positive, the results of this work showed that CPS was negative in both stages of the Tri-Flo separator. The Ecart probable value for the first stage of the separator (Epf = 0.023) was rather greater than the second stage (Eps = 0.018), representing the higher performance achieved in the second stage. In addition, the Tri-Flo operational parameters were found to be adjustable on the basis of raw coal specifications in order to reach good metallurgical results. Therefore, the optimum operational feed capacities of the Tri-Flo separator were determined to be in the range of 80-140 t/h, depending on the type of raw coal.
H. Haghgouei; A. Reza Kargar; M. H. Khosravi; M. Amini
Abstract
In many engineering constructions, the foundations should be built adjacent to each other. Therefore, the effect of interfering of close foundations should be considered in the design stage. In this research work, the effect of interference of closely separated foundations resting on a slope on the elastic ...
Read More
In many engineering constructions, the foundations should be built adjacent to each other. Therefore, the effect of interfering of close foundations should be considered in the design stage. In this research work, the effect of interference of closely separated foundations resting on a slope on the elastic settlement is investigated by considering a semi-analytical solution. The distribution of stress due to the footing pressure in the slope is computed by a proposed Airy stress function, and then by employing the finite difference scheme, the displacement of the footings is calculated. The results obtained show that by increasing the distance between the foundations, the interference influence on the ratio of settlement will be diminished. However, this behavior is highly linked to the slope characteristics. For a slope with a height of 10 times of footing width, beyond an S/B ratio larger than 10, the effect of interference is not tangible, and the footings behave like an isolated foundation. By decreasing the slope height, this behavior will occur at a lower S/B.
Exploitation
E. Bakhtavar; A. Jafarpour; S. Yousefi
Abstract
In order to catch up with reality, all the macro-decisions related to long-term mining production planning must be made simultaneously and under uncertain conditions of determinant parameters. By taking advantage of the chance-constrained programming, this paper presents a stochastic model to create ...
Read More
In order to catch up with reality, all the macro-decisions related to long-term mining production planning must be made simultaneously and under uncertain conditions of determinant parameters. By taking advantage of the chance-constrained programming, this paper presents a stochastic model to create an optimal strategy for producing bimetallic deposit open-pit mines under certain and uncertain conditions. The uncertainties of grade, price per product, and capacities of the various stages in the process of production of the final product were considered. The results of solving the deterministic and stochastic models showed that the stochastic model had a greater compatibility and performance than the other ones.
Sh. Rahimi; M. Ataee-pour; H. Madani
Abstract
Methane has been known as a safety risk for the coal mining activities. Accordingly, one can mitigate this risk, and hence, the level of hazard to which the mining workers are exposed, by predicting the possible exceedance of allowable methane dosage should be provided with a reliable information on ...
Read More
Methane has been known as a safety risk for the coal mining activities. Accordingly, one can mitigate this risk, and hence, the level of hazard to which the mining workers are exposed, by predicting the possible exceedance of allowable methane dosage should be provided with a reliable information on the distribution of methane across the working face considering the uncertainties associated with the gas content of such deposits. In this work, the gas content uncertainty in a coal seam is first investigated using the geo-statistical simulation. Then a method is proposed in order to predict methane gas emission based on the Monte Carlo random simulation method. Next, the results obtained are introduced into a 3D Computational Fluid Dynamics (CFD) model to estimate the methane distribution considering the uncertainty associated with the gas content. Defined as zones where the methane concentration is so high that an explosion is much likely to occur, the elevated methane zones (EMZs) are delineated across the working faces. The results obtained show that UGC has an impact on the ventilation parameters and EMZs. The proposed method could be carried out in order to guide the ventilation design in improving safety.
Hadi Fattahi
Abstract
The uniaxial compressive strength of weak rocks (UCSWR) is among the essential parameters involved for the design of underground excavations, surface and underground mines, foundations in/on rock masses, and oil wells as an input factor of some analytical and empirical methods such as RMR and RMI. The ...
Read More
The uniaxial compressive strength of weak rocks (UCSWR) is among the essential parameters involved for the design of underground excavations, surface and underground mines, foundations in/on rock masses, and oil wells as an input factor of some analytical and empirical methods such as RMR and RMI. The direct standard approaches are difficult, expensive, and time-consuming, especially with highly fractured, highly porous, weak, and homogeneous rocks. Numerous endeavors have been made to develop indirect approaches of predicting UCSWR. In this research work, a new intelligence method, namely relevance vector regression (RVR), improved by the cuckoo search (CS) and harmony search (HS) algorithms is introduced to forecast UCSWR. The HS and CS algorithms are combined with RVR to determine the optimal values for the RVR controlling factors. The optimized models (RVR-HS and RVR-CS) are employed to the available data given in the open-source literature. In these models, the bulk density, Brazilian tensile strength test, point load index test, and ultrasonic test are used as the inputs, while UCSWR is the output parameter. The performances of the suggested predictive models are tested according to two performance indices, i.e. mean square error and determination coefficient. The results obtained show that RVR optimized by the HS model can be successfully utilized for estimation of UCSWR with R2 = 0.9903 and MSE = 0.0031203.
Hasan Alizadeh; Mahnaz Nedaei; Negar Tirandaz
Abstract
One of the significant negative factors involved in exploiting granite stones as ornamental stones is the presence of heterogeneous fractures within the rock mass. Joints can either be destructive or beneficial in the production granite piles and building stone mines depending on their characteristics. ...
Read More
One of the significant negative factors involved in exploiting granite stones as ornamental stones is the presence of heterogeneous fractures within the rock mass. Joints can either be destructive or beneficial in the production granite piles and building stone mines depending on their characteristics. This work focuses on evaluating the joints in the Divchal mine area of Kelardasht, north Iran. To get to that point, the main faults are surveyed from the aerial photograph, geological and tectonic maps, and field observations. According to this implementation, a density map of faults is provided for the entire studied area. The characteristics of the main joints including the length, slope, number, and orientation are collected in the mine area. The volumetric percentage of joints ( ) and joint set spacing ( ) parameters are computed at specific stations to identify suitable locations for granite extraction. The findings of this work suggest that the lower the value of ( < 10), the larger the blocks can be extracted. On the other hand, at the high values, the width of the extraction block increases. These conditions are typically found in locations far from the main faults where the density of joints is low, and as a result, the distance between joints is higher. The values > 60 indicate a crushed rock mass, and are typically observed in clay-free shear zones. It is recommended that the opening of the working face be avoided in situations near the main faults due to the fragmentation of rocks and denser joint spacing.
Exploration
Kamran Mostafaei; Mohammad Nabi Kianpour; Mahyar Yousefi
Abstract
Mineral prospectivity mapping (MPM) is a multi-staged process aiming at delimiting exploration targets. Experts’ knowledge is an indispensable component of MPM, and might be required (i) while translating signature features of ore-forming processes into a suite of maps, namely evidence layers, ...
Read More
Mineral prospectivity mapping (MPM) is a multi-staged process aiming at delimiting exploration targets. Experts’ knowledge is an indispensable component of MPM, and might be required (i) while translating signature features of ore-forming processes into a suite of maps, namely evidence layers, (ii) while assigning weights to evidence layers, and (iii) while interpreting maps of mineral prospectivity. The latter is important as MPM integrates weighted evidence layers into a continuous map of mineral prospectivity. Although high values in prospectivity maps pertain to prospective zones, maps of mineral prospectivity are devoid of interpretation. One, therefore, should adopt a classification scheme to categorize or prioritize exploration targets from a map of mineral prospectivity. In addition to previous frameworks applied for interpreting maps of mineral prospectivity, this paper introduces an optimization-based framework, the Gray Wolf Optimizer (GWO) algorithm, for addressing this problem. In addition to GWO, we also used percentile maps of 85, 90, and 95% for interpreting the results of our prospectivity model. These methods were applied to a fuzzy-based map of mineral prospectivity derived for the Alut area, NW Iran. Overall, the map derived by the GWO has involved more Au occurrences, 66% of explored Au occurrences by GWO versus 33% by percentile maps; also introduces more targets as high-potential zones of Au mineralization that may be neglected by traditional methods like percentile maps.
Rock Mechanics
Hamed Farajollahi; Mohammad Mohammadi; Mohammad Hossein Khosravi
Abstract
A better understanding of rock mass behavior is an essential part of the design and construction of underground structures. Any improvement in the understanding of the behavior of rock mass will facilitate the improvement of the design in terms of the safety of the working environment, long-term safety ...
Read More
A better understanding of rock mass behavior is an essential part of the design and construction of underground structures. Any improvement in the understanding of the behavior of rock mass will facilitate the improvement of the design in terms of the safety of the working environment, long-term safety of the structure, environmental effects, and sound management of public or private resources. Thus, in step one in this paper the experience gained from the application of the GDE (Geo Data Engineering) multiple graph approach for rock mass classification and assessment of its behavior through the course of excavation of the Alborz tunnel is presented. The predicted hazards are compared with the experienced problems and suggestions are given to be considered in future works of tunnel construction. In step two, the GDE multiple graph approach is compared to the rock mass behavior types proposed by Palmstrom & Stille (2007) in terms of the continuity of rock mass. The result of this comparison together with the data obtained from rock mass classification in the Alborz tunnel are used to develop a system that determines the applicability of the rock bolt supporting factor (RSF) in different rock mass behavior classes.
Exploitation
E. Ghasemi
Abstract
In underground excavation, where the road-headers are employed, a precise prediction of the road-header performance has a vital role in the economy of the project. In this paper, a new model is developed for prediction of the road-header performance using the non-linear multivariate regression analysis. ...
Read More
In underground excavation, where the road-headers are employed, a precise prediction of the road-header performance has a vital role in the economy of the project. In this paper, a new model is developed for prediction of the road-header performance using the non-linear multivariate regression analysis. This model is able to estimate the instantaneous cutting rate (ICR) of roadheader based on rock properties such as Brazilian tensile strength (BTS), rock mass cuttability index (RMCI), and alpha angle (α: is the angle between the tunnel axis and the planes of weakness). In order to construct and test the proposed model, a database including 62 cutting cases is used in the Tabas coal mine No. 1 in Iran. Various statistical performance indices were employed to evaluate the model efficiency. The results obtained indicate that the proposed non-linear regression model can be efficiently used to predict the road-header cutting performance. Furthermore, the prediction capacity of this model is better than the empirical models developed previously. Finally, it should be noted that the developed model is site-specific, and it can be used for preliminary estimation of ICR in future phases of Tabas coal mine No. 1. The outcome of this model can be helpful in adjustment of time-scheduling of the project.
Rock Mechanics
R. Rafiee; A. Azarfar
Abstract
One of the main concerns of an underground coal mining engineer is the safety and stability of the mine. One way that the safety and stability can be ensured is to know and understand the coal mine geology and how it reacts to the mining process. One technique that has shown a lot of success in the coal ...
Read More
One of the main concerns of an underground coal mining engineer is the safety and stability of the mine. One way that the safety and stability can be ensured is to know and understand the coal mine geology and how it reacts to the mining process. One technique that has shown a lot of success in the coal mining industry for geologic technical evaluation purposes is the coal mine roof rating (CMRR). The CMRR classification is based on geotechnical data taken from the immediate roof layers within the mine. Since the uncertainty exists in geotechnical data, and CMRR process depends on the expert’s idea implicitly, the final value may be inaccurate. In this paper, the fuzzy type 2 is used to overcome this uncertainty. To design the fuzzy system for calculating the CMRR, only quantitative variables (UCS, spacing, and persistence) are considered as fuzzy inputs. Finally, the scores of CMRR and FCMRR for four units of Riccall mine are compared.
Exploitation
P. Afzal; M. Yusefi; M. Mirzaie; E. Ghadiri-Sufi; S. Ghasemzadeh; L. Daneshvar Saein
Abstract
The aim of this work was to delineate the prospects of podiform-type chromite by staged factor analysis and geochemical mineralization prospectivity index in Balvard area, SE Iran. The stream sediment data and fault density were used as the exploration features for prospectivity modeling in the studied ...
Read More
The aim of this work was to delineate the prospects of podiform-type chromite by staged factor analysis and geochemical mineralization prospectivity index in Balvard area, SE Iran. The stream sediment data and fault density were used as the exploration features for prospectivity modeling in the studied area. In this regard, two continuous fuzzified evidence layers were generated and integrated using fuzzy operator. Then fractal modeling was used for defuzzification of the prospectivity model obtained. Furthermore, the prediction-area plot was used for evaluation of the predictive ability of the generated target areas. The results obtained showed that using the prospectivity model, 82% of mineral occurrences was predicted in 18% of the studied area. In addition, the target areas were correlated with the geological particulars including ultrabasic and serpentinization rocks, the host rocks of the podiform-type chromite deposit type.
M. Davood Yavari; H. Haeri; V. Sarfarazi; M. Fatehi Marji; H. A. Lazemi
Abstract
Investigating the crack propagation mechanism is of paramount importance in analyzing the failure process of most materials. This process may be exposed during each kind of loading on the materials. In this work, the cracking mechanism in rock-like materials is studied using the numerical methods and ...
Read More
Investigating the crack propagation mechanism is of paramount importance in analyzing the failure process of most materials. This process may be exposed during each kind of loading on the materials. In this work, the cracking mechanism in rock-like materials is studied using the numerical methods and compared with the experimental test results. However, the mechanism of crack growth in brittle materials such as rocks is influenced by different parameters. This research work focuses on the effect of the initial crack angles on the crack growth paths of these materials. Some cubic samples containing pre-existing cracks are tested in compression by considering different flaw orientations. The specimens are made of cement, water, and sand. Moreover, the mentioned process is numerically simulated using three different methods: the finite difference method for discontinuous bodies or discrete element method, the displacement discontinuity method, and the versatile finite element method. The micro-parameters for simulation are gained by the trial-and-error procedure for the discrete element method. Eventually, the crack growth paths observed in the experiments are compared with the numerically simulated models. The results obtained show that these central cracks propagate in two ways, which are dependent on their initial angle. By increasing the initial crack angle to greater than 30° (α > 30°), the wing crack path moves further away from the initial crack, and by decreasing α to smaller than 30° (α < 30°), only the shear cracks are initiated. Therefore, the validity and accuracy of the results are manifested by comparing all the corresponding results obtained by different methods. Based on these results, it can generally be concluded that the strength of the cubic (rock material) specimens increases with increase in the crack angles with respect to the applied loading direction.
S. Akbari; Sh. Zare; H. Chakeri; H. Mirzaei Nasir Abad
Abstract
Evaluation of the interaction between a new and the existing underground structures is one of the important problems in urban tunneling. In this work, using FLAC3D, four numerical models of single- and twin-tube tunnels in urban areas are developed, where the horizontal distance between the single- and ...
Read More
Evaluation of the interaction between a new and the existing underground structures is one of the important problems in urban tunneling. In this work, using FLAC3D, four numerical models of single- and twin-tube tunnels in urban areas are developed, where the horizontal distance between the single- and twin-tube tunnels are varied. The aim is to analyze the effects of the horizontal distances, considering various criteria such as the deformation of linings, the forces and moments exerted on the twin-tube tunnels and their safety factors, the subsidence that occur on the surface and the nearby buildings, the stability of the single-tube tunnel, and the stability of the pillar lying between the single- and twin-tube tunnels. Considering the above-mentioned criteria, the results obtained indicate that the interaction between the single- and twin-tube tunnels is virtually negligible in the distance more than three times the single-tube tunnel diameter. Also the stability of the pillar lying between the tunnels makes the distance to be chosen at least 1.5 times the single-tube tunnel diameter.
Azadeh Agah; Faramarz Doulati Ardejani; Mohamad Javad Azinfar
Abstract
This work investigates the reactive transport of volatile hydrocarbons in the unconfined aquifer system of Tehran oil refinery and the industrial area of Ray, Tehran. A 2D finite volume model is presented to predict the soil gas contamination caused by LNAPL traveling on the phreatic surface through ...
Read More
This work investigates the reactive transport of volatile hydrocarbons in the unconfined aquifer system of Tehran oil refinery and the industrial area of Ray, Tehran. A 2D finite volume model is presented to predict the soil gas contamination caused by LNAPL traveling on the phreatic surface through the vadose zone of the aquifer incorporating physical, chemical, and biological processes. A multi-purpose commercial software called PHOENICS is modified by incorporating extra codes to solve the model equations numerically. The model predictions closely agree with the field measurements, showing that the LNAPL migration is typically affected by the volatilization process. LNAPLs represent a potential long-term source of soil and groundwater contamination in the studied site. A comparison of the simulation results in a time step of 36 years with the results of field studies shows that the presented numerical model can simulate the reaction transfer of evaporated hydrocarbons in the unsaturated region. The concentrations have decreased in the time step of 36 years compared to the values shown in the time step of 50 years. This decrease in the hydrocarbon gas-phase concentrations in the unsaturated zone is due to excavations at the site for field studies. Through these excavations, a significant volume of the gaseous phase trapped below the earth's surface is released into the atmosphere, which reduces the accumulation of volatile gases beneath the earth's surface.
Vaibhav Sharma; Andy Kwame Yeboah; Joshua Asare; Natillio Pillay; Jaspreet Singh
Abstract
The presence of any underground cavity in the soil stratum can seriously harm the structural performance of the overlying facility. These may develop because of mining, tunneling, water, and gas networks or outdated channels. In the present investigation, a circular void is considered, and its effect ...
Read More
The presence of any underground cavity in the soil stratum can seriously harm the structural performance of the overlying facility. These may develop because of mining, tunneling, water, and gas networks or outdated channels. In the present investigation, a circular void is considered, and its effect on the surface strip footing (in the form of ultimate load (UL), ultimate settlement (US), footing tilting, and footing horizontal displacement (HD)) is studied using numerical simulation. The variable parameters are load eccentricity (e), load inclination (α), and geogrid reinforcement location (u). It is observed that as the load inclination and eccentricity increases, the UL decreases. For instance, in the unreinforced soil, u/B = 0, at load inclination of α = 0°, 10°, 20°, and 30°, the UL is 249, 200, 142, and 97 kN/m, respectively. Moreover, as the geo-grid location is changed, the UL first increases when placed near the footing (u/B = 0.10), and thereafter, starts to decrease as the distance between footing and geo-grid increases. For instance, the UL is 249, 278, 267, 260, 259, and 256 kN/m when e/B = 0.0, α = 0°, and u/B varies from 0 to 0.5 with an increment of 0.1. The tilting increases as the eccentricity is increased; for example, u/B = 0.0 for α = 0°; the tilting values are 0°, 0.12°, 0.31°, and 0.61°. Moreover, as the load eccentricity increases, the HD decreases (for u/B = 0.1 and α = 10°, the HD is 4.20, 3.5, 3.00, and 2.60 mm, respectively.
Rock Mechanics
H. Zebarjadi Dana; R. Khaloo Kakaie; R. Rafiee; A.R. Yarahmadi Bafghi
Abstract
Slope stability analysis is one of the most important problems in mining and geotechnical engineering. Ignoring the importance of these problems can lead to significant losses. Selecting an appropriate method to analyze the slope stability requires a proper understanding of how different factors influence ...
Read More
Slope stability analysis is one of the most important problems in mining and geotechnical engineering. Ignoring the importance of these problems can lead to significant losses. Selecting an appropriate method to analyze the slope stability requires a proper understanding of how different factors influence the outputs of the analyses. This paper evaluates the effects of considering the real geometry, changes in the mesh size, and steepness of the slope, as the dimensional effects, and changes in the geomechanical parameters, as the media effects on the global slope stability of an open-pit mine using finite difference methods with a strength reduction technique. The case study is the Tectonic Block I in the old pit (steep slope) and the redesigned new pit (gentle slope) of the Choghart iron mine. In the first step, a series of 2D and 3D slope stability analyses are performed and compared in terms of safety and potential failure surface. The results obtained show that by considering the real geometry of the slope, the FOS3D/FOS2D ratio (3D-effect) is more than 1 in the all cases. The 3D-effect in the new pit is smaller than that in the old one. In the next step, sensitivity analysis of the cohesion and the friction angle is performed for the 2D and 3D analyses. The results obtained show that the sensitivity of the analyses in terms of the 3D-effect to the change in the friction angle, especially in a low-friction angle, is more significant than that to the change in the cohesion.
Rock Mechanics
H. Sarfaraz; M. H. Khosravi; M. Amini
Abstract
In layered and blocky rock slopes, toppling failure is a common mode of instability that may occur in mining engineering. If this type of slope failure occurs as a consequence of another type of failure, it is referred to as the secondary toppling failure. “Slide-head-toppling” is a type ...
Read More
In layered and blocky rock slopes, toppling failure is a common mode of instability that may occur in mining engineering. If this type of slope failure occurs as a consequence of another type of failure, it is referred to as the secondary toppling failure. “Slide-head-toppling” is a type of secondary toppling failures, where the upper part of the slope is toppled as a consequence of a semi-circular sliding failure at the toe of the slope. In this research work, the slide-head-toppling failure is examined through a series of numerical modeling. Phase 2, as a software written based on the finite element method, is used in this work. Different types of slide-head-toppling failures including blocky, block-flexural, and flexural are simulated. A good agreement can be observed when the results of the numerical modeling are compared with those for the pre-existing physical modeling and analytical method.
Rock Mechanics
Mohammad Rezaei; Seyed Pourya Hosseini; Danial Jahed Armaghani; Manoj Khandelwal
Abstract
This paper presents an experimental-statistical study investigating the influence of five joint properties: density, filling type, angle, aperture, and roughness on the longitudinal wave velocity (LWV) of concrete samples. To achieve this, each of the five properties is categorized into distinct groups ...
Read More
This paper presents an experimental-statistical study investigating the influence of five joint properties: density, filling type, angle, aperture, and roughness on the longitudinal wave velocity (LWV) of concrete samples. To achieve this, each of the five properties is categorized into distinct groups with specific intervals. Concrete samples measuring 15*15*15 cm are prepared in the laboratory based on an optimal combination of 75% sand, 15% cement, and 10% water. The LWV values of these samples are then measured. The experimental results indicate that joint density, roughness, and aperture have an inverse relation with LWV, resulting in reductions of 82%, 22.5% and 49%, respectively. Additionally, an approximate sinusoidal relationship between LWV and joint angle is established, leading to a variation of approximately 10% in LWV values for different joint angles. To evaluate the effect of joint filling on LWV, various filling materials, including iron oxide, calcite, silica, clay, and gypsum are used, resulting in approximately a 34% variation in LWV values. It was found that gypsum filling yields the highest LWV value while iron oxide filling produces the lowest. Furthermore, analysis of variance (ANOVA) confirms that a polynomial quadratic equation best represents the relation between LWV and each of the joint characteristics, with determination coefficient (R2) values ranging from 0.694 to 0.99. Finally, a verification study using "validation samples" demonstrates the acceptable accuracy for the proposed equations, with minimum relative errors ranging from 3% to 13%, a low root mean square error of 189.08 m/s, and a high R2 value of 0.926. This research enhances understanding of wave propagation through jointed rock masses with varying joint characteristics and provides theoretical support for rock reorganization and dynamic stability analysis of rock masses.
Exploration
Jairo Jhonatan Marquina Araujo; Marco Antonio Cotrina Teatino; José Nestor Mamani Quispe; Eduardo Manuel Noriega Vidal; Juan Antonio Vega Gonzalez; Juan Vega-Gonzalez; Juan Cruz-Galvez
Abstract
The objective of this research work to employ machine learning techniques including Multilayer Perceptron Artificial Neural Networks (ANN-MLP), Random Forests (RFs), Extreme Gradient Boosting (XGBoost), and Support Vector Regression (SVR) to predict copper ore grades in a copper deposit located in Peru. ...
Read More
The objective of this research work to employ machine learning techniques including Multilayer Perceptron Artificial Neural Networks (ANN-MLP), Random Forests (RFs), Extreme Gradient Boosting (XGBoost), and Support Vector Regression (SVR) to predict copper ore grades in a copper deposit located in Peru. The models were developed using 5654 composites containing available geological information (rock type), as well as the locations of the samples (east, north, and altitude) and secondary ore grade (Mo) obtained from drilling wells. The data was divided into 10% (565 composites) for testing, 10% (565 composites) for validation, and 80% (4523 composites) for training. The evaluation metrics included SSE (Sum of Squared Errors), RMSE (Root Mean Squared Error), NMSE (Normalized Mean Squared Error), and R² (Coefficient of Determination). The XGBoost model could predict the ore grade with an SSE of 15.67, RMSE = 0.17, NMSE = 0.34, and R² = 0.66, the RFs model with an SSE of 16.40, RMSE = 0.17, NMSE = 0.36, and R² = 0.65, the SVR model with an SSE of 19.94, RMSE = 0.19, NMSE = 0.43, and R² = 0.57, and the ANN-MLP model with an SSE = 21.00, RMSE = 0.19, NMSE = 0.46, and R² = 0.55. In conclusion, the XGBoost model was the most effective in predicting copper ore grades.
S. Zare; M. Maleki Moghaddam; J. Pourshaabadi
Abstract
The energy consumed by the comminution equipment accounts for the main part of the operating cost of the mineral processing plants. In order to conserve energy, attempts were made to increase the efficiency of the conventional comminution equipment. As a case study, in this research work, a process audit ...
Read More
The energy consumed by the comminution equipment accounts for the main part of the operating cost of the mineral processing plants. In order to conserve energy, attempts were made to increase the efficiency of the conventional comminution equipment. As a case study, in this research work, a process audit was carried out in the comminution plant of the Steel-Sirjan Iron Ore Complex in order to find the low-cost solutions to improve the product quality and decrease the maintenance and operating costs. Three main steps of the audit were (1) studying the operating manuals and checking the standard process procedures, (2) process data analyzing, and (3) proposing and implementing the proper solutions. Plant audit revealed a low equipment efficiency. The main defects were the crusher operation in the half-full condition, high pressure grinding roll (HPGR) operation in a non-standard condition, high amounts of rejected materials in the HPGR circuit, and low efficiency of the screen. Following this, a series of modifications were made in the crushing and grinding circuit. This consequently caused an increase of 9.3% in the crushing plant throughput in the choked condition of the crushers as opposed to the half-full condition. By increasing the HPGR operational pressure and the hopper level, BBWI of the HPGR product in the super-choked condition was decreased from 16± 0.20 kWh/t to 14.9± 0.25 kWh/t. By modifying the screen process, the circulating load decreased from 79% to 59%, and the screen efficiency increased from 63.5% to 89.5%.The energy consumed by the comminution equipment accounts for the main part of the operating cost of the mineral processing plants. In order to conserve energy, attempts were made to increase the efficiency of the conventional comminution equipment. As a case study, in this research work, a process audit was carried out in the comminution plant of the Steel-Sirjan Iron Ore Complex in order to find the low-cost solutions to improve the product quality and decrease the maintenance and operating costs. Three main steps of the audit were (1) studying the operating manuals and checking the standard process procedures, (2) process data analyzing, and (3) proposing and implementing the proper solutions. Plant audit revealed a low equipment efficiency. The main defects were the crusher operation in the half-full condition, high pressure grinding roll (HPGR) operation in a non-standard condition, high amounts of rejected materials in the HPGR circuit, and low efficiency of the screen. Following this, a series of modifications were made in the crushing and grinding circuit. This consequently caused an increase of 9.3% in the crushing plant throughput in the choked condition of the crushers as opposed to the half-full condition. By increasing the HPGR operational pressure and the hopper level, BBWI of the HPGR product in the super-choked condition was decreased from 16± 0.20 kWh/t to 14.9± 0.25 kWh/t. By modifying the screen process, the circulating load decreased from 79% to 59%, and the screen efficiency increased from 63.5% to 89.5%.
M. Zahiri; K. Goshtasbi; J. Khademi Hamidi; K. Ahangari
Abstract
There is a direct relationship between the efficiency of mechanized excavation in hard rocks and that of disc cutters. Disc cutter wear is an important effective factor involved in the functionality of tunnel boring machines. Replacement of disc cutters is a time-consuming and costly activity that can ...
Read More
There is a direct relationship between the efficiency of mechanized excavation in hard rocks and that of disc cutters. Disc cutter wear is an important effective factor involved in the functionality of tunnel boring machines. Replacement of disc cutters is a time-consuming and costly activity that can significantly reduce the TBM utilization and advance rate, and has a major effect on the total time and cost of the tunneling projects. When these machines bore through hard rocks, the cutter wear considerably affects the excavation process. To evaluate the performance of the cutters, first, it is essential to figure out how they operate the rock cutting mechanism; secondly, it is important to identify the key factors that cause the wear. In this work, we attempt to introduce a comprehensive numerical method for estimation of disc cutter wear. The field data including the actual cutter wear more than 1000 pieces and the geological parameters along the Kani-Sib transmission tunnel in the northwest of Iran are compiled in a special database that is subjected to a statistical analysis in order to reveal the genuine wear rule. The results obtained from the numerical method indicate that with an increase in the wear of disk cutter up to 25 mm, the applied normal and rolling forces can be multiplied by 2.9 and 2.7, respectively, and by passing the critical wear, the disk cutters lose their optimal performance. This method also shows that confining pressure will increase the wear of the disc cutter. By the proposed formulation, the cutter consumption rate can be predicted with a high accuracy.
