Mohammad Omidi manesh; Vahab Sarfarazi; Nima Babanouri; Amir Rezaei
Abstract
This work presents the hollow center cracked disc (HCCD) test and the cracked straight through Brazilian disc (CSTBD) test of oil well cement sheath using the experimental test and Particle Flow Code in two-dimensions (PFC2D) in order to determine mode I fracture toughness of cement sheath. The tensile ...
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This work presents the hollow center cracked disc (HCCD) test and the cracked straight through Brazilian disc (CSTBD) test of oil well cement sheath using the experimental test and Particle Flow Code in two-dimensions (PFC2D) in order to determine mode I fracture toughness of cement sheath. The tensile strength of cement sheath is 1.2 MPa. The cement sheath model is calibrated by outputs of the experimental test. Secondly, the numerical HCCD model and CSTBD model with diameter of 100 mm are prepared. The notch lengths are 10 mm, 20 mm, 30 mm, and 40 mm. The tests are performed by the loading rate of 0.018 mm/s. When the notch length in CSTBD is 40 mm, the external work is decreased 48%, related to the maximum external work of model with notch length of 10 mm (0.225 KN*mm decreased to 0.116 KN*mm). When the notch length in HCCD is 30 mm, the external work is decreased 33%, related to the maximum external work of model with notch length of 10 mm (0.06 KN*mm decreased to 0.04 KN*mm). The fracture energy is largely related to the joint length. The fracture energy is decreased by increasing the notch length. In constant to the notch length, the fracture energy of the CSTBD model is more than the HCCD model. Mode I fracture toughness is constant by increasing the notch length. The HCCD test and the CSTBD test yield a similar fracture toughness due to a similar tensile stress distribution on failure surface. The experimental outputs are in accordance to the numerical results.
Exploration
Jabar Habashi; Majid Mohammady Oskouei; Hadi Jamshid Moghadam
Abstract
The studied area located in eastern Iran shows a high potential for various mineralizations, especially copper due to its tectonic activity. Remote sensing data can effectively distinguish these areas because of the sparse vegetation. Therefore, in this study, the ASTER (Advanced Spaceborne Thermal Emission ...
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The studied area located in eastern Iran shows a high potential for various mineralizations, especially copper due to its tectonic activity. Remote sensing data can effectively distinguish these areas because of the sparse vegetation. Therefore, in this study, the ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) multi-spectral data was used to recognize argillic, sericite, propylitic, and iron oxide alterations associated with copper mineralization. For this purpose, two categories (porphyry copper-iron and advanced argillic-iron) related alterations were considered to perform the classification of a 2617 square kilometer area using a neural network classification algorithm. To evaluate the accuracy of the classifier, the confusion matrix was computed, which provides overall accuracy and the kappa coefficient factors for assessing classification accuracy. As a result, 64.17% and 83.5% of overall accuracy, and 0.602 and 0.807 of the kappa coefficient were achieved for the advanced argillic alterations and porphyry copper categories, respectively. Ultimately, the validation of the classifications was carried out using the normalized score (NS) equation, employing quantitative criteria. Notably, the advanced argillic class emerged with the top normalized score of 2.25 out of 4, signifying a 56% alignment with the geological characteristics of the region. Consequently, this outcome has led to the identification of favorable areas in the central and northeastern parts of the studied area.
M. Anemangely; A. Ramezanzadeh; B. Tokhmechi
Abstract
Achieving minimum cost and time in reservoir drilling requires evaluating the effects of the drilling parameters on the penetration rate and constructing a drilling rate estimator model. Several drilling rate models have been presented using the drilling parameters. Among these, the Bourgoyne and Young ...
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Achieving minimum cost and time in reservoir drilling requires evaluating the effects of the drilling parameters on the penetration rate and constructing a drilling rate estimator model. Several drilling rate models have been presented using the drilling parameters. Among these, the Bourgoyne and Young (BY) model is widely utilized in order to estimate the penetration rate. This model relates several drilling parameters to the penetration rate. It possesses eight unknown constants. Bourgoyne and Young have suggested the multiple regression analysis method in order to define these constants. Using multiple regressions leads to physically meaningless and out of range constants. In this work, the Cuckoo Optimization Algorithm (COA) is utilized to determine the BY model coefficients. To achieve this goal, the corresponding data for two wells are collected from one of the oilfields located in SW of Iran. The BY model constants are determined individually for two formations in one of the wells. Then the determined constants are used to estimate the drilling rate of penetration in the other well having the same formations. To compare the results obtained for COA, first, the two mathematical methods including progressive stochastic and multiple regressions were implemented. Comparison between these methods indicated that COA yields more accurate and reliable results with respect to the others. In the following, Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) as meta-heuristic algorithms were applied on the field data in order to determine BY model’s coefficients. Comparison between these methods showed that the COA has fast convergence rate and estimation error less than others.
Rock Mechanics
H. Mohammadi; H. Darbani
Abstract
There are various criteria that need to be examined alongside each other when designing a longwall mining system. Challenges such as determination of the supported roof width, support system design, caving height determination, lateral or chain pillar size determination, and optimum support design for ...
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There are various criteria that need to be examined alongside each other when designing a longwall mining system. Challenges such as determination of the supported roof width, support system design, caving height determination, lateral or chain pillar size determination, and optimum support design for the main gate and tail gate roadways have to be tackled for this aim. Three-dimensional analysis would deliver the highest accuracy of induced stresses around the longwall working area. Thus, the main purpose of this paper is to develop a three dimensional geometrical computing model (3GCM) for calculating the induced stresses in both longitudinal and transverse loading orientations of the extraction panel. 3GCM is capable of studying the changes of induced stresses along the longitudinal orientation of working and the lateral pillar as well as the induced stresses ahead and behind of the face. The proposed computational model, for analyzing the vertical induced stresses, was used in one of the longwall workings in the Parvade-2 coal mine of Tabas, Iran. Validation of 3GCM has approved its high efficiency for the analysis of induced stresses within the working as well as surrounding areas.
Exploration
A. Habibnia; Gh. R. Rahimipour; H. Ranjbar
Abstract
Hanza region is located in the southern part of Urumieh–Dokhtar Metallogenic belt in southeastern Iran. This region includes six known porphyry copper deposits and it is considered as an ore- bearing region from geochemical point of view. The aim of this research is to examine effective processing ...
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Hanza region is located in the southern part of Urumieh–Dokhtar Metallogenic belt in southeastern Iran. This region includes six known porphyry copper deposits and it is considered as an ore- bearing region from geochemical point of view. The aim of this research is to examine effective processing techniques in the analysis of stream sediment geochemical datasets and ASTER satellite images. The processing methods have led to identification of eight new prospective areas. These methods are aimed at providing univariate geochemical maps. The stream sediment geochemical mapping for Cu and Mo was performed by the sample catchment basin approach. The results derived from this approach have been mapped in four classes associated with the first quartile, third quartile and threshold values obtained from Median Absolute Deviation method. False-colour composite and band ratio techniques were adopted as two well-known methods for the processing of an ASTER scene spanning the study area. Eight new targets for possible mineralization have been resulted from geochemical data analyses. Image processing techniques on the ASTER multispectral data have also revealed widespread hydrothermal alterations associated with the known porphyry copper deposits and the new prospects.
Mineral Processing
A.R. Javadi
Abstract
Carnallite, with the chemical formula KMgCl3.6H2O, is a mineral that was first discovered in the Urals Mountains in Russia. The reverse flotation has been established for carnallite processing in the current decades, and the alkyl morpholine collector is used for the removal of NaCl from carnallite using ...
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Carnallite, with the chemical formula KMgCl3.6H2O, is a mineral that was first discovered in the Urals Mountains in Russia. The reverse flotation has been established for carnallite processing in the current decades, and the alkyl morpholine collector is used for the removal of NaCl from carnallite using the reverse flotation. The carnallite processing method involves reverse flotation with the dodecyl morpholine collector, and then centrifugation and cold crystallization. In this research work, kimiaflot 619, as a new collector, is synthesized, and the bench-scale flotation shows that kimiaflot 619 reveals a better selectivity and affinity for the NaCl crystals at an acidic pH with a less collector dosages–only 1/2 of the Armoflot 619 collector. The flotation results indicate that the NaCl grade in carnallite concentrated by Armoflot 619 (200 g/t) is 2.86%, while the NaCl grade in carnallite concentrated by kimiaflot 619collector (100 g/t) is 2.75%. The frother’s stability of the Armoflot 619 collector after flotation is very high and uncontrollable, while kimiaflot 619 has solved this problem, and it is completely controllable.
Pooria Kianoush; Ghodratollah Mohammadi; Seyed Aliakbar Hosseini; Nasser Keshavazr Faraj Khah; Peyman Afzal
Abstract
In the seismic methods, estimation of the formation pressures is obtained by converting the seismic velocity to the pore pressure, and comparing it with the effective pressure during the well-test program. This work is a new challenge regarding the velocity study domain in an oil field in SW Iran. The ...
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In the seismic methods, estimation of the formation pressures is obtained by converting the seismic velocity to the pore pressure, and comparing it with the effective pressure during the well-test program. This work is a new challenge regarding the velocity study domain in an oil field in SW Iran. The reservoir generally consists of carbonate rocks, and contains no shale interbeds. Here, 23 well information, seismic data interpretation, compressional (Vp), and shear velocity (Vs) models are implemented. The models are determined from the combined geo-statistical methods, and the results obtained are compared with the fractal models. The final Vs cube is modeled in order to determine the formation fracture pressure using the exploratory well cores and dipole sonic imager (DSI) Vs logs with a correlation coefficient of 0.95 for the Vs data obtained from the porosity, lithology, and primary DSI data. The vertical seismic profiling (VSP) data introduce a maximum interval velocity of 2760-2900 m/s in the field related to the Gotnia formation. The final amounts of seismic acoustic impedance inversion (AI) at the bottom of the field are mostly in the range of 8000-15000 [(m/s)*(g/cm3)], which can be related to the calcareous formations. Based on the Logratio matrix obtained from the fractal velocity-volume (Vp-V) model, the maximum overall accuracy (OA) in the dominant limestone intervals is 0.74. It indicates a high correlation of the Vp cube model obtained from the combination of sequential Gaussian simulation (SGS) and co-kriging models with AI. The uncertainty studies of Vp model in blind wells are about 50%, which is acceptable considering the large well numbers.
V. Sarfarazi
Abstract
In this work, the interaction between the semi-circular space and the neighboring joint with and without the presence of rock bolts was investigated using the particle flow code (PFC) approach. For this purpose, firstly, the calibration of PFC was performed using both the Brazilian experimental test ...
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In this work, the interaction between the semi-circular space and the neighboring joint with and without the presence of rock bolts was investigated using the particle flow code (PFC) approach. For this purpose, firstly, the calibration of PFC was performed using both the Brazilian experimental test and the uniaxial compression test. Secondly, a numerical model with the dimension of 100 mm * 100 mm was prepared. A semi-circular space with a radius of 25 mm was situated below the model. A joint with a length of 40 mm was situated above the space. The joint opening was 2 mm. The joint angles related to the horizontal direction were 0°, 15°, 30°, 45°, 60°, and 75°. Totally, 6 different configurations of the semi-circular space and neighboring joint were prepared. These models were tested with and without the presence of vertical rock bolts by the biaxial test. The rock bolt length was 50 mm. The value of the lateral force was fixed at 2 MPa. An axial force was applied to the model till the final failure occurred. The results obtained showed that the presence of rock bolts changed the failure pattern of the numerical model. In the absence of rock bolts, two tensile wing cracks initiated from the joint tip and propagated diagonally till coalescence from the model boundary. Also several shear bands were initiated in the left and right sides of the tunnel. In the presence of rock bolts, several shear bands were initiated in the left and right sides of the tunnel. The compressive strength with the presence of rock bolts was more than that without the presence of rock bolts. The failure stress had a minimum value when the joint angle was 45°.
Amir Rezaei; Vahab Sarfarazi; Nima Babanouri; Mohammad Omidi manesh; Shirin Jahanmiri
Abstract
Non-persistent joints are geologic occurrences in rocks that weaken pillars because they are present within them. Using practical tests and numerical models, it has been determined how edge notches affect the way pillars break. Gypsum samples that are notched and have dimensions of 70 mm by 70 mm by ...
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Non-persistent joints are geologic occurrences in rocks that weaken pillars because they are present within them. Using practical tests and numerical models, it has been determined how edge notches affect the way pillars break. Gypsum samples that are notched and have dimensions of 70 mm by 70 mm by 50 mm are created. Gypsum's Young modulus, Poisson ratio, compressive strength, and tensile strength are 5.5 GPa, 0.27, 8 MPa, and 1.1 MPa, respectively. 10-, 20-, and 30-degree notch angles are used. The model receives an axial stress at a rate of 0.05 mm/min. On a rock pillar, numerical simulation is carried out concurrently with an experimental test. The findings indicate that the joint angle is mostly responsible for the failure process. The fracture pattern and failure mechanism of the pillars are connected to the compressive strengths of the specimens. At the notch points, two significant splitting tensile fractures spread vertically until coalescing with the top and lower boundaries of the models. On the left and right sides of the pillar, two rock columns are also taken out. The overall number of cracks rises as sample loading increases. The model's deformation at the start of loading reflect a linear elastic behavior, and the number of fractures steadily grows. When the number of cracks increases, the curve becomes non-linear, and the force being applied peaks. When the sample can no longer tolerate the applied force, a dramatic stress decrease occurs. The macro-failure over the whole model is what leads to the greater stress decrease following the peak load. In actuality, the reduced stress reduction is accompanied by more overall fractures. Similar findings are shown in both the experimental testing and numerical modeling.
Exploration
M. Honarmand; H. Ranjbar; H. Shahriari; F. Naseri
Abstract
This research was performed with the objective of evaluating the accuracy of spectral angle mapper (SAM) classification using different reference spectra. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital images were applied in the SAM classification in order to map the ...
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This research was performed with the objective of evaluating the accuracy of spectral angle mapper (SAM) classification using different reference spectra. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) digital images were applied in the SAM classification in order to map the distribution of hydrothermally altered rocks in the Kerman Cenozoic magmatic arc (KCMA), Iran. The study area comprises main porphyry copper deposits such as Meiduk and Chahfiroozeh. Collecting reference spectra was considered after pre-processing of ASTER VNIR/SWIR images. Three types of reference spectra including image, USGS library, and field samples spectra were used in the SAM algorithm. Ground truthing and laboratory studies including thin section studies, XRD analysis, and VNIR-SWIR reflectance spectroscopy were utilized to verify the results. The accuracy of SAM classification was numerically calculated using a confusion matrix. The best accuracy of 74.01% and a kappa coefficient of 0.65 were achieved using the SAM method using field samples spectra as the reference. The SAM results were also validated with the mixture tuned matched filtering (MTMF) method. Field investigations showed that more than 90% of the known copper mineralization occurred within the enhanced alteration areas.
Exploitation
R. Razzaghzadeh; R. Shakoor Shahabi; A. Nouri Qarahasanlou
Abstract
The appropriate operating of mining machines is affected by both the executive and environmental factors. Considering the effects and the related risks lead to a better understanding of the failures of such machines. This leads to a proper prediction of the reliability parameters of such machines. In ...
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The appropriate operating of mining machines is affected by both the executive and environmental factors. Considering the effects and the related risks lead to a better understanding of the failures of such machines. This leads to a proper prediction of the reliability parameters of such machines. In this research work, the reliability and maintainability analysis of the loading and haulage machines in the Sungun Copper Mine, considering the repair condition as multiple repairable units, was performed. For this purpose, the data necessary for the loading and haulage equipment including 2 loaders and 8 dump trucks for a 15-month period was collected and categorized in 10 operational units after the system and sub-systems of the department were determined. Initially, the time between failures (TBFs) and time to repair (TTR) for each unit was calculated. Then 20 sub-systems were developed. Primarily, the Stata software was utilized to carry out the heterogeneity test for all the sub-systems. In consequence, most of the sub-systems were regarded as the heterogeneous ones, except for 7 of them including the dump truck units 1, 2, 3, 4, 5, 7, and 8 in TBFs. Hence, "PHM" that is a covariate-based model displayed the heterogeneous group. Its reliability function was also estimated. For the next step, the trend tests were done on the non-heterogeneous sub-systems by means of the Minitab software. The homogeneous sub-systems with failure trend were modeled by “NHPP”. Afterwards, the non-trended sub-systems formed the data group. Later, the correlation tests were modeled by “HPP”. Finally, the reliability and maintainability functions were calculated with the 95% confidence level.
Rock Mechanics
Mohsen Khanizadeh Bahabadi; Alireza Yarahamdi Bafghi; Mohammad Fatehi Marji; Hossein Shahami; Abolfazl Abdollahipour
Abstract
Complexity of geomaterial’s behavior is beyond the capabilities of conventional numerical methods alone for realistically model rock structures. Coupling of numerical methods can make the numerical modeling more realistic. Discontinuous Deformation Analysis (DDA) and Displacement Discontinuous ...
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Complexity of geomaterial’s behavior is beyond the capabilities of conventional numerical methods alone for realistically model rock structures. Coupling of numerical methods can make the numerical modeling more realistic. Discontinuous Deformation Analysis (DDA) and Displacement Discontinuous Method (DDM) are hybridized for modeling block displacement and crack propagation mechanism in a blocky rock mass. DDA is used to compute the displacements of the blocks, and DDM is used to predict the crack propagation paths due to the specified boundary conditions. The displacements obtained from DDA are converted into stress and considering Kelvin's solution of the problem the crack propagation mechanism within each block is investigated. Boundary stresses are updated due to crack propagation and new stress boundary conditions in DDA. This cycle continued until crack propagation stopped or a new block formed. Numerical solutions of the experimental rock samples including two random cracks with crack 1 fixed and crack 2 created with different angles and one crack with a slope angle of 30 degrees are compared with the existing experimental and numerical results. This comparison validates the accuracy and effectiveness of the proposed procedure because crack propagation paths predicted are in good agreement with the corresponding experimental results of rock samples.
H. Rasouli; K. Shahriar; H. Madani
Abstract
When longwall mining involves total extraction, it includes the overlying strata movements. In order to better control these movements, the height of fracturing (HoF) must be determined. HoF includes both the caved and continuous fractured zones, and represents the region of the broken ground whereby ...
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When longwall mining involves total extraction, it includes the overlying strata movements. In order to better control these movements, the height of fracturing (HoF) must be determined. HoF includes both the caved and continuous fractured zones, and represents the region of the broken ground whereby a hydraulic connection to the mined seam occurs. Among the various empirical models for predicting HoF, the Ditton's geometry and geology models are widely used in the Australian coalfields. This work uses a case-based reasoning (CBR) method in order to predict HoF. The model's variables, including the panel width (W), cover depth (H), mining height (T), key stratum thickness (t), and its distance from the mined seam (y), are selected via the Buckingham's p-theorem. The data set consisting of 31 longwall panels is partitioned into the training and test subsets using the W/H ratio as the primary classifier of a semi-random partitioning method. This partitioning method overcomes the class imbalance and sample representativeness problems. A new CBR model presents a linear mathematical equation to predict HoF. The results obtained show that the presented model has a high coefficient of determination (= 0.99) and a low average error (AE = 8.44 m). The coefficient of determination for the CBR model is higher than that for the Ditton’s geometry (= 0.93) and geology (= 0.97) models. Contrary to the Ditton's models, the performance of the CBR model is consistent regarding the average and standard errors (AE and SE) of the training and test stages. The proposed model has an acceptable performance for all the width to depth ratios to predict HoF.
M.A. Chamanzad; M. Nikkhah
Abstract
Drilling and blasting have numerous applications in the civil and mining engineering. Due to the two major components of rock masses, namely the intact rock matrix and the discontinuities, their behavior is a complicated process to be analyzed. The purpose of this work is to investigate the effects of ...
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Drilling and blasting have numerous applications in the civil and mining engineering. Due to the two major components of rock masses, namely the intact rock matrix and the discontinuities, their behavior is a complicated process to be analyzed. The purpose of this work is to investigate the effects of the geomechanical and geometrical parameters of rock and discontinuities on the rock mass blasting using the UDEC software. To this end, a 2D distinct element code (DEM) code is used to simulate the stress distribution around three blast holes in some points and propagation of the radial cracks caused by blasting. The critical parameters analyzed for this aim include the normal stiffness (JKN) and shear stiffness (JKS), spacing, angle and persistence of joint, shear and bulk modulus, density of rock, and borehole spacing. The results obtained show that the joint parameters and rock modulus have very significant effects, while the rock density has less a effect on the rock mass blasting. Also the stress level has a direct relationship with JKN, JKS, bulk modulus, and the shear modulus has an inverse relationship with the rock density. Moreover, the stress variation in terms of spacing and joint angle indicates sinusoidal and repetitive changes with the place of target point with respect to the blast hole and joint set. Also with a decrease in the JKN and JKS values, the radial cracked and plastic zones around a blast hole show more development. With increase in the joint persistence, the plastic zones decrease around a blast hole.
Elahe Ghaemmaghami; Mohamad Reza Samadzadeh Yazdi; Mohammad Amin Darvishi; Ali akbar Sadati; Abbas Najafi
Abstract
As the mass ratio of alumina to silica (A/S ratio) in bauxite decreases, the cost of alumina production by the Bayer process sharply increases. With the increasingly fierce competition in the alumina industry and the gradual reduction in bauxite grade, when the A/S ratio drops to 3-4, the Bayer process ...
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As the mass ratio of alumina to silica (A/S ratio) in bauxite decreases, the cost of alumina production by the Bayer process sharply increases. With the increasingly fierce competition in the alumina industry and the gradual reduction in bauxite grade, when the A/S ratio drops to 3-4, the Bayer process is challenging to meet the market competition and production requirements. In such cases, the alumina production by sintering method has a vast development prospect and application potential for low-grade bauxite ores. The low A/S ratio and the high iron oxide content are the difficulties in the alumina production by the sintering process. This work adopts the lime-soda sinter process for extracting alumina from bauxite samples (A/S ratio = 1.34 and 20.80% Fe2O3) of the Semirom mine in Iran. The effects of sintering parameters are investigated. The maximum alumina extraction (88%) was obtained by a CaO/SiO2 molar ratio of 1.2, Na2O/Al2O3 molar ratio of 0.9, and sintering temperature at 1250 °C for 80 min. Also 83% of alumina is extracted by decreasing the N/A ratio to 0.66, to decrease the sodium carbonate consumption for a more economical process. The sintered materials are leached with sodium carbonate solution, and aluminum hydroxide [Al(OH)3] is precipitated. Finally, pure alumina (Al2O3) is obtained with a purity of 98 % after calcination at 1200 °C for 2 hours.
Mineral Processing
Nooshin Navi; Mohammad Karamoozian; Mohammad Reza Khani
Abstract
Red mud is an important solid tailing with strong alkalinity that is obtained during the extraction of alumina in the Bayer process. The global reserve of red mud is more than 4 billion tons, and its disposal as tailing has always been a serious environmental problem. This tailing is considered as a ...
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Red mud is an important solid tailing with strong alkalinity that is obtained during the extraction of alumina in the Bayer process. The global reserve of red mud is more than 4 billion tons, and its disposal as tailing has always been a serious environmental problem. This tailing is considered as a potential source, due to its high content of valuable metal compounds including iron. In this research work, the extraction of iron in red mud is investigated by the method of reduction roasting. The main influencing factors are also investigated. These methods include reduction in muffle and tube furnace, and temperature, reduction agent, and additive type are as important factors. Reduction roasting of the samples in a tube furnace, with Argon gas and vacuum, a mixture of red mud, graphite, and sodium carbonate at 700–1000 °C results in the formation of Fe3O4. Magnetic measurements indicate that saturation magnetization increases from 0.239 to 38.205 emu/g due to the formation of Fe3O4. Applying the magnetic field intensity of about 1000 Gauss results in the iron recovery of 89.9%.
Mineral Processing
Alireza Javadi
Abstract
The main and economic mineral of antimony is stibnite or antimony sulfide, and the research and processes in the world are based on it, and oxide minerals are not considered among the economic and important reserves of antimony due to the difficulty of processing and the lack of optimal efficiency of ...
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The main and economic mineral of antimony is stibnite or antimony sulfide, and the research and processes in the world are based on it, and oxide minerals are not considered among the economic and important reserves of antimony due to the difficulty of processing and the lack of optimal efficiency of the flotation method. On the other hand, taking into account that a large part of the antimony reserve of Sefidabeh is made up of low-grade oxidized ore; this research on the method of economic extraction and the possibility of recovering this type of reserve will be important due to the strategic nature of antimony metal. According to the experiments conducted in this research, the effective parameters for flotation include: pH, collector concentration, activator concentration, depressant concentration, activator type, and humic acid concentration. DX7 software was used for statistical modeling of experiments. Based on the above parameters, the design of the experiment was carried out using a partial factorial method and finally the number of 16 experiments was determined for the effect of the above factors on the grade and weight recovery of the sample. Antimony ore flotation with a grade of 4.32% was carried out in a two-stage method. In this method, in the first stage, flotation of antimony sulfur (stibnite, Sb2S3) was performed at a specific pH by adding the activator of copper sulfate or lead nitrate and the depressant together, potassium amyl xanthate collector and MIBC. In the second stage of flotation, the tailings of the first stage of flotation for antimony oxides were treated with a sodium oleate collector (with determined concentrations) at a specific pH by adding copper sulfate or lead nitrate activator, sodium oleate collector and humic acid and MIBC frother agent. The interaction between pH and activator concentration (BD) has a direct effect on the amount of concentrated antimony, with an increase in pH from 6 to 8 antimony when using an activator concentration of 300 g/t, and a decrease when using an activator concentration of 500 g/t. Flotation was done. In the best conditions, with two-stage flotation of antimony, 68.99% recovery and 13.32 grade were obtained.
Negar Saeidi; Dariush Azizi; Mohammad Noaparast; Soheila Aslani; R Ramadi
Abstract
In this paper, iron ore sample from the Chadormalu was investigated to determine some comminution properties. Chadormalu deposit is one of the largest iron ore mine in Iran, which is located in Yazd province. The representative ore sample contained 57%Fe, 0.9%P and 0.17%S. The sample was crushed; afterward, ...
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In this paper, iron ore sample from the Chadormalu was investigated to determine some comminution properties. Chadormalu deposit is one of the largest iron ore mine in Iran, which is located in Yazd province. The representative ore sample contained 57%Fe, 0.9%P and 0.17%S. The sample was crushed; afterward, it was ground in various grinding times according to the Bond Ball mill approach to specify the work index values. Based on different grinding times and the obtained results, a new work index equation was then simulated through which grinding time was considered as the main variable. The relationships between work index, the work input and P80 were then concluded. In addition, the results of tests were then used to estimate the selection function parameter. A new equation was applied to determine energy efficiency which could be implemented for energy consumption calculation. Two equations for EB and EB/Elimit were then obtained, where EB is the efficiency of comminution, and the ELimit is the maximum limiting energy efficiency for particle fracture under compressive loading. These equations could estimate the parameters of the iron ore would be precisely estimated. Indeed, by means of work index value; some crushing and grinding characteristics of the taken sample were assessed by which comminution circuit would be designed much better.
Environment
B. Shokouh Saljoughi; A. Hezarkhani; E. Farahbakhsh
Abstract
The most significant aspect of a geochemical exploration program is to define and separate the anomalous values from the background. In the past decades, geochemical anomalies have been identified by means of various methods. Most of the conventional statistical methods aiming at defining the geochemical ...
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The most significant aspect of a geochemical exploration program is to define and separate the anomalous values from the background. In the past decades, geochemical anomalies have been identified by means of various methods. Most of the conventional statistical methods aiming at defining the geochemical concentration thresholds for separating anomalies from the background have limited the efficiency in the areas with complex geological settings. In this work, three methods including the Concentration-Area (C-A) and Spectrum-Area (S-A) fractal models, and the U-statistic method are applied to identify the geochemical anomalies in Avanj porphyry system due to a complex geological and tectonic setting. The results obtained show that the S-A and U-statistic methods present more acceptable outputs than the C-A method. The C-A model acts well to identify the geochemical anomalies within a region including a simple geochemical background; however, the model has limitations within a region including a complex geological setting, where each sub-area is characterized by different geochemical fields. The U-statistic method, by considering the location of sampling points, their spatial relation, and radius of influence for each point in the estimation of anomaly location, overcomes the limitations of the C-A model. The S-A model is a powerful tool to decompose mixed geochemical patterns into a geochemical anomaly map and a varied geochemical background map. The output of this method shows the analysis of geochemical data in the frequency domain, which can provide new exploratory information that may not be revealed in the spatial domain. Eventually, it can be pointed out that the accuracy of the S-A fractal model for determining the thresholds is higher than the other two methods mentioned.
A. Agah; N. Falahati
Abstract
In this research work, the potential capability of nano-clay and tonsil, as low-cost and domestic adsorbents, for the elimination of a cationic dye, (CR18) from contaminated water is investigated. The surface properties of the adsorbents are studied by means of the scanning electron microscopy (SEM) ...
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In this research work, the potential capability of nano-clay and tonsil, as low-cost and domestic adsorbents, for the elimination of a cationic dye, (CR18) from contaminated water is investigated. The surface properties of the adsorbents are studied by means of the scanning electron microscopy (SEM) and X-ray diffraction techniques. The effects of the initial dye concentration, pH, stirring speed, contact time, and adsorbent dosage are investigated at 25 . The results obtained show that the dye adsorption data from the nano-clay and tonsil experiments fit well to the Langmuir and Freundlich isotherms, respectively. The results of dye adsorption kinetics demonstrate that the adsorption system follows a pseudo-second-order model with a satisfactory correlation value (R=99%).The adsorption thermodynamics is also studied, concluding that the adsorption process is spontaneous and physically controlled. Under the optimum conditions (pH of 7, stirring speed of 200 rpm, CR18 concentration of 30 ppm and contact time of 30 min), the adsorption capacities of the mixed adsorbents show the maximum adsorption efficiency at the tonsil:nano-clay weight ratio of 1:2.
Rock Mechanics
R. Shafiei Ganjeh; H. Memarian; M. H. Khosravi; M. Mojarab
Abstract
Dynamic slope stability in open-pit mines still remains a challenging task in the computational mining design. Earthquake and blasting are two significant sources of dynamic loads that can cause many damages to open-pit mines in active seismic areas and during exploitation cycles. In this work, the effects ...
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Dynamic slope stability in open-pit mines still remains a challenging task in the computational mining design. Earthquake and blasting are two significant sources of dynamic loads that can cause many damages to open-pit mines in active seismic areas and during exploitation cycles. In this work, the effects of earthquake and blasting on the stability of the NW slope of Chadormalu mine are compared by a numerical modeling method. The dynamic results show that the maximum displacement under earthquake and blasting loads within the slope are 844 mm and 146 mm, respectively. According to the shear strain results, both the earthquake and blasting waveforms are destructive, while the earthquake waveforms cause more damages to the slope. Moreover, the deterministic and probabilistic seismic hazard analyses are carried out to assess the seismicity of the mine area. The experimental results indicate that the maximum values for the vertical and horizontal accelerations are 0.55 g and 0.75 g, respectively. The maximum calculated acceleration is then scaled to the selected earthquake accelerograms. In order to show the effective impact of the established scale, the model is executed using the original accelerograms. The results obtained show that the established scale prevents overestimation and underestimation of the displacement and strain. Therefore, applying scaled accelerograms in a dynamic slope stability analysis in mine slopes leads to more reliable and robust results. The overall results show that a strong earthquake causes plenty of damages to the slope, and consequently, interrupts the mining cycle. Hence, the seismic study and dynamic slope stability should be considered as a part of the computational mining design.
Exploitation
M. Hosseini; H. Madani; K. Shahriar
Abstract
The main purpose of this work is modeling the dispersion of the sarin gas in a subway station in a hypothetical scenario. The dispersion is modeled using the CFD approach. In the analysis of the environmental conditions of the underground spaces, the only factor that draws a distinction between a subway ...
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The main purpose of this work is modeling the dispersion of the sarin gas in a subway station in a hypothetical scenario. The dispersion is modeled using the CFD approach. In the analysis of the environmental conditions of the underground spaces, the only factor that draws a distinction between a subway station and other spaces is the train piston effect. Therefore, the present research work models the sarin dispersion in the two general cases of with and without a train in the subway system. About 0.5 L of sarin is assumed to be released through the main air handling unit (AHU) of the station. The results obtained show that in the case with no train service in the station, after 20 minutes of sarin release, the concentration and dose of sarin in the station will be 8.9 mg/m3 and 80 mg minute/m3, respectively, and these values are highly dangerous and lethal, and would have severely adverse effects on many individuals, and lead to death. This is highly important, especially when the effect of ventilation chambers at the ground level is taken into consideration. The results obtained also show that the train piston effect reduces the concentration and dose of sarin in the station so that when train arrival at and departure from the station, the sarin dose considerably reduces to 25 mg min/m3 after the release, and contributes to lower casualties. Finally, the results obtained show that time is a key factor to save lives in the management of such incidents.
Rock Mechanics
H. Sarfaraz; M. Amini
Abstract
One of the most important instabilities of rock slopes is toppling failure. Among the types of toppling failure, block-flexural failures are more common instability which occurs in nature. In this failure, some rock blocks break because of tensile stresses, and some overturn under their weights, and ...
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One of the most important instabilities of rock slopes is toppling failure. Among the types of toppling failure, block-flexural failures are more common instability which occurs in nature. In this failure, some rock blocks break because of tensile stresses, and some overturn under their weights, and next to all of them topple together. Physical and theoretical modeling of this failure is studied by Amini et al. in 2015. Due to the complexity of this failure mechanism, no appropriate numerical model has been proposed so far. In this research, first, a literature review of toppling failure is summarized. Then, using UDEC software as distinct element method (DEM), the experimental models were analyzed numerically, and Voronoi joint model was applied to simulate the failure. The results of numerical simulations are compared with the outcomes of physical models and analytical solution. The comparison illustrates that numerical modeling has good agreement with corresponding experimental tests and theoretical approach. Also, the results show that although the mechanism of block-flexural toppling failure is complicated, the numerical code is well capable to analyze of this failure.
Enayatallah Emami Meybodi; Syed Khaliq Hussain; Mohammad Fatehi Marji
Abstract
In this research work, X-ray diffraction (XRD) tests and petrographic studies are performed to analyze the mineral composition and lamination in the shale rock specimens. Afterward, point load (PL) and uniaxial compressive strength (UCS) tests are carried out on the anisotropic laminated shale rock. ...
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In this research work, X-ray diffraction (XRD) tests and petrographic studies are performed to analyze the mineral composition and lamination in the shale rock specimens. Afterward, point load (PL) and uniaxial compressive strength (UCS) tests are carried out on the anisotropic laminated shale rock. Based on the macro-mechanical properties of these tests, the discrete element method implemented in a two-dimensional particle flow code (PFC2D) is adjusted to numerically simulate the shale rock specimens. The aim of this work is to validate the numerical models by failure process, stress-strain curves, and peak failure strengths of the shale samples. Therefore, point load test is used for assessing the pattern failure mechanism, and uniaxial compressive strength test is performed for obtaining the stress-strain curves and peak strength failure points in the laboratory shale rock samples. Validation of peak strengths criteria provides the best results; the determination coefficient values for lab and numerical modeling with (R2 = 0.99). Several numerical models are prepared for estimating the mechanical behavior of shale rocks in PFC2D. The smooth joint model (SJM) is used for preparing the consistent and appropriate constitutive models for simulating the mechanical behavior of laminated shale. It is concluded that SJM provides more reasonable results for laminated shale rock that can be used for several petroleum engineering projects, especially in the central geological zone of Iran.
Rock Mechanics
Taha Ansari; Hamid Chakeri; Mohammad Darbor; sadegh Amoun; Hadi Shakeri
Abstract
There is no acceptable method for investigating the tool wear phenomenon in soft grounds. In this article, first, a new equipment made at Sahand University of Technology is introduced, which is used for simulation of TBM tunneling mechanism. Next, the effect of various soil grading parameters such as ...
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There is no acceptable method for investigating the tool wear phenomenon in soft grounds. In this article, first, a new equipment made at Sahand University of Technology is introduced, which is used for simulation of TBM tunneling mechanism. Next, the effect of various soil grading parameters such as D10, D30, and D60 (which indicate the corresponding diameters on the soil grading diagram where 10, 30, and 60% of the grains are smaller than these values, respectively), coefficient of gradation, uniformity coefficient, sorting coefficient and effective size on the cutting tools wear. The initial studies show that in soils with fine grains greater than 10%, by increase in the values of D10, D30, D60, and effective size, the tool wear increases. However, in soils with fine grains less than 10%, by increase in the above-mentioned parameters, the soil abrasiveness reduces. Also in soils with more than 10% fine grains, by increase in the coefficient of gradation value, the soil abrasiveness reduces. But in soils with fine grains less than 10%, by increase in the value of this parameter, the tool wear increases. The results of experiments show that sorting coefficient could be a good criterion for investigating the soil abrasiveness.
