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.
vahab sarfarazi; Mohammad Omidi manesh; 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.
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.
M Mohammadiun; B. Dahrazma; Seyed F. Saghravani; A. Khodadadi Darban
Abstract
Use of nanotechnology has proven to be a promising approach toward remediation of all phases of environment. The aim of this work is to investigate the effects of different parameters on using iron III oxide nanoparticles in a continuous flow configuration for the removal of Cd2+ ionsfrom contaminated ...
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Use of nanotechnology has proven to be a promising approach toward remediation of all phases of environment. The aim of this work is to investigate the effects of different parameters on using iron III oxide nanoparticles in a continuous flow configuration for the removal of Cd2+ ionsfrom contaminated soils. Also selective sequential extraction tests are carried out to evaluate the nanoparticle tendency to remove cadmium from different fractions of soils. In order to achieve this goal, a specific flow rate of a nanoparticle solution was passed through a soil sample in a column with 3 cm diameter and 4 cm height. Up to 100% of cadmium removal was achieved by providing a nano-fluid concentration of 500 ppm, pH of 6.5, treatment duration of 24 hours, and flow rate of 0.5 mL/min. Evaluation of the results obtained showed that the tendency of the iron oxide nanoparticles to remove cadmium from different fractions of contaminated soil was in the order of exchangeable > carbonates > oxides and hydroxides > organic matter > residual. The results obtained from this work can be used to develop an appropriate remediation protocol for contaminated soils.
F. Sharifi; A.R. Arab Amiri; A. Kamkar Rouhani
Abstract
The generalized effective-medium theory of induced polarization (GEMTIP) is a newly developed relaxation model that incorporates the petro-physical and structural characteristics of polarizable rocks in the grain/porous scale to model their complex resistivity/conductivity spectra. The inversion of the ...
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The generalized effective-medium theory of induced polarization (GEMTIP) is a newly developed relaxation model that incorporates the petro-physical and structural characteristics of polarizable rocks in the grain/porous scale to model their complex resistivity/conductivity spectra. The inversion of the GEMTIP relaxation model parameter from spectral-induced polarization data is a challenging issue because of the highly non-linear dependency of the observed data on the model parameter and non-uniqueness of the problem. To solve these problems as well as scape the local minima of the highly complicated cost function, the genetic algorithm (GA) can be applied but it has proven to be time-intensive computationally. However, this drawback can be resolved by incorporating a faster algorithm, e.g. particle swarm optimization (PSO). The aim of this work is to investigate whether recovering the model parameter of the ellipsoidal GEMTIP model from SIP data using the combined GA and PSO algorithms is possible. To achieve this aim, we set the best calculated individuals using GA as the search space of PSO, and then the best location achieved by PSO in each iteration is assigned as the updated model parameters. The results of our research work reveal that the model parameters can effectively be recovered using the approach proposed in this paper but the time constant of a noisy data that arises from the adverse dependency of this parameter on the ellipticity of a polarizable grain. Moreover, the execution time of the ellipsoidal GEMTIP modeling of complex resistivity data can be significantly improved using the proposed algorithm.
H. Ebadi; P. Pourghahramani; B. Nemati akhgar
Abstract
Structural changes of mechanically-activated ilmenite during milling by a planetary mill are monitored and determined as a function of the milling time. The maximum specific BET surface area of 10.76 m2/g is obtained after 150 min of milling. The results obtained indicate that agglomeration of the particles ...
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Structural changes of mechanically-activated ilmenite during milling by a planetary mill are monitored and determined as a function of the milling time. The maximum specific BET surface area of 10.76 m2/g is obtained after 150 min of milling. The results obtained indicate that agglomeration of the particles occurs after 45 min of milling. The maximum X-ray amorphization degree of ca. 95% has been calculated after 150 min of milling. Estimation of the stored energy reveals that the X-ray amorphization degree has a dominant contribution to the excess enthalpy of the activated materials. The surface-weighted crystallite size in the ground ilmenite reaches 4.45 nm, which corresponds to the volume-weighted crystallite size of 8 nm and 11.18 nm obtained by the Williamson-Hall and Rietveld methods, respectively. After 150 min of mechanical activation, the root mean square strain, , increases to 0.78%, which corresponds to the strains of 1.43% and 1.04% obtained from the Williamson-Hall and Rietveld methods, respectively. Reduction in the crystallite size leads to the contraction of the ilmenite unit cell after 150 min. The reaction rate constant of the ilmenite dissolution increases by over 58 times after 150 min of milling. Activation energy of the dissolution reaction decreases from 57.45 kJ/mol to 41.09 kJ/mol after 150 min of milling.
D. Fakhri; M. Hosseini; M. Mahdikhani
Abstract
Fracture toughness is an important concrete property that controls crack extension and concrete fracture. Concrete is the most widely used material in civil engineering containing the most conventional and cheapest materials. Accordingly, cracks and fractures may cause irreparable damages. To this end, ...
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Fracture toughness is an important concrete property that controls crack extension and concrete fracture. Concrete is the most widely used material in civil engineering containing the most conventional and cheapest materials. Accordingly, cracks and fractures may cause irreparable damages. To this end, fibre-reinforced concretes have been recently constructed in order to overcome the aforementioned weaknesses. Crack propagation and fracture toughness of various concrete specimens are analyzed by the straight notched Brazilian disc (SNBD) test. The specimens are conventional concrete lacking micro-silica and limestone powder, and those containing various volume percentages of fibers including the concrete specimens containing 0.35% individual polypropylene (PP) fibers, 0.35% individual glass fibers, concrete specimens containing 0.17% PP and 0.18% glass fibers, and concrete fibers containing 0.1% PP and 0.25% glass fibers. Micro-silica has replaced 10 wt% cement in all fiber-reinforced concrete specimens, and limestone has replaced 5 wt% cement. Crack extension from the pre-existing cracks in the specimens and mode I, mode II, and mixed-mode fracture toughness are calculated. The BD test is performed on the specimens at the crack inclination angles of 0°, 15°, 28.83°, 45°, 60°, 75°, and 90°. The experimental results show the initiation of wing cracks at angles less than 60° (0 < α < 60°) from the tip of the pre-existing cracks. The crack growth and propagation path approach the loading direction by continuing loading. However, the cracks are initiated at a distance of d from the crack tip at angles larger than 60°. The observed distance is larger in the fiber-less specimens than in the fiber-reinforced specimens. The concrete specimens reinforced by 0.17% PP and 0.18% glass hybrid fibers containing micro-silica and limestone powder showed the highest mode I, mode II, and mixed-mode fracture toughness compared to the other concrete specimens.
J. Ziaei; S. Ghadernejad; A. Jafarpour; R. Mikaeil
Abstract
One of the most crucial factors involved in the optimum design and cost estimation of rock sawing process is the rock abrasivity that could result in a significant cost increase. Various methods including direct and indirect tests have been introduced in order to measure rock abrasivity. The Schimazek’s ...
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One of the most crucial factors involved in the optimum design and cost estimation of rock sawing process is the rock abrasivity that could result in a significant cost increase. Various methods including direct and indirect tests have been introduced in order to measure rock abrasivity. The Schimazek’s F-abrasiveness factor ( ) is one of the most common indices to assess rock abrasivity. is the function of three rock parameters including the Brazilian tensile strength ( ), median grain size ( ), and equivalent quartz content ( ). By considering its formulation, it has been revealed that the coefficient of each parameter is equal, which is not correct because each parameter plays a different role in the rock abrasion process. This work aims to modify the original form of by introducing three correction factors. To calculate these correction factors, an integrated method based on a combination of the statistical analysis and probabilistic simulation is applied to a dataset of 15 different andesite rocks. Based on the results obtained, the values of -0.36, 0.3, and -0.89 are suggested as the correction factors of , and , respectively. The performance of the modified Schimazek’s F-abrasiveness factor ( ) is checked not only by the wear rate of diamond wire but also by the cutting rate of the wire sawing process of Andesite rocks. The results obtained indicate that the wear rate and cutting rate of andesite rocks can be reliably predicted using . However, it should be noted that this work is a preliminary one on the limited rock types and further studies are required by incorporating different rock types.
Exploitation
S. Maleki; F. Sotoudeh; F. Sereshki
Abstract
Ventilation is a vital component of an underground mining operation, used to guarantee a safe atmosphere for workers and survive them from the hazardous and toxic gases. In the recent years, engineers have begun to apply new operation research techniques in order to optimize the ventilation systems to ...
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Ventilation is a vital component of an underground mining operation, used to guarantee a safe atmosphere for workers and survive them from the hazardous and toxic gases. In the recent years, engineers have begun to apply new operation research techniques in order to optimize the ventilation systems to assist in achieving a regulatory compliance, reduce ventilation costs, and improve its efficiency. Airflow regulation optimization in mine ventilation networks is described as a minimization model whose objective function is a minimum number of regulators and energy consumption. In this work, all the previously accomplished works were first reviewed. Then a ventilation system was designed for the Western-Razmja coal mine by a manual method, and an axial fan was proposed. Subsequently, the same ventilation system was simulated using the VENTSIM 3D software. The results obtained by computer simulation showed that there was a reliable relation between the manual method and the simulation approach. In the final step, the GAMS software was used to solve a Mathematical Programming (MP) problem to minimize the overall cost of ventilation by determination of the optimum location for the fan and regulators. The final results of this work illustrated that not only the number of regulators were reduced through solving the MP model but also the total resistance of the Western-Razmja coal mine was reduced by 14% from 1.6 to 1.3. Furthermore, it was observed that the total efficiency of the proposed fan was increased.
Mineral Processing
H. Ebadi; P. Pourghahramani; E. Dehgani; M. Ganjeh
Abstract
In this work, the effects of temperature, acid concentration, and mechanical activation on dissolution of ilmenite were studied using the statistical design of experiment technique. Mechanical activation was carried out using a planetary ball mill in dry mode, and the resulting structural changes were ...
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In this work, the effects of temperature, acid concentration, and mechanical activation on dissolution of ilmenite were studied using the statistical design of experiment technique. Mechanical activation was carried out using a planetary ball mill in dry mode, and the resulting structural changes were characterized by the particle size analysis, specific surface area measurements, and X-ray diffraction method. The results obtained indicated that intensive milling led to a significant decrease in the ilmenite particle size and that after 20 minutes, particles tended to agglomerate. However, after 90 minutes, the BET specific surface area increased to 9.36 m2/g. In addition to surface changes, mechanical activation led to intense changes and disorders in the crystal structure of ilmenite as amorphization degree increased to 94.30% and the volume weighted crystallite size and lattice strain changed from 346 nm and 0.13% to 14 nm and 1.44%, respectively. The results of the dissolution tests in the form of experimental design indicated that a suitable model could fit the experimental data in 95% confidence level. The coefficient factors for acid concentration, mechanical activation, and temperature were 3.75%, 33.04%, and 9%, respectively. Mechanical activation had the highest effect on titanium extraction in comparison to the other factors involved. Also in addition to its dominant effect on ilmenite dissolution, it also weakened the temperature effect. However, the results of the kinetic tests proved that mechanical activation led to promotion of the temperature effect on increasing the dissolution reaction rate in the initial stages. Finally, a dissolution yield of more than 98% was achieved through 90 minutes of activation at 95° C and 55 wt.% acid concentration.
Sh. Khosravimanesh; M. Cheraghi Seifabad; R. Mikaeil; R. Bagherpour
Abstract
In most rock drilling operations, the low rate of penetration (ROP) can be primarily attributed to the presence of the cuttings produced during drilling and the thermal stresses caused by friction at the bit-rock interface, which can be exacerbated with the increasing strength, hardness, and abrasivity ...
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In most rock drilling operations, the low rate of penetration (ROP) can be primarily attributed to the presence of the cuttings produced during drilling and the thermal stresses caused by friction at the bit-rock interface, which can be exacerbated with the increasing strength, hardness, and abrasivity of the drilled rock. In order to improve ROP, drill bit lifetime, and cutting power, it is necessary to minimize the process forces due to the mechanical bit-rock interaction and the thermal stresses generated in the drill hole. Any improvement in these areas is extremely important from both the technical and the economic perspectives. This improvement can be achieved by the use of appropriate cooling/lubricating fluids in the drilling process in order to increase ROP, reduce the temperature of the drilling environment, and create a clean drill hole free of cuttings. In this work, a series of laboratory drilling tests are performed to investigate and compare ROP in the drilling of seven samples of hard and soft rock in the presence of six different cooling-lubricating fluids. The drilling tests are performed on the cubic specimens with a laboratory-scale drilling rig at several different rotation speeds and thrust forces. The statistical analyses are performed in order to investigate the relationship between ROP and the mechanical properties of the rock, properties of the fluid, and machining parameters of the drilling rig. These analyses show that under similar conditions in terms of mechanical properties of the rock using Syncool with a concentration of 1:100 and soap water with a concentration of 1:120 instead of pure water leads to the average 31% and 37% increased ROP in granite, 36% and 43% increased ROP in marble, and 47% and 61% increased ROP in travertine, respectively. These results demonstrate the good performance of these cooling/lubricating fluids in increasing ROP.
A. Alimoradi; B. Maleki; A. Karimi; M. Sahafzadeh; S. Abbasi
Abstract
The exploration methods are divided into the direct and indirect categories. Among these, the indirect geophysical methods are more time- and cost-effective compared with the direct methods. The target of the geophysical investigations is to obtain an accurate image from the underground features. The ...
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The exploration methods are divided into the direct and indirect categories. Among these, the indirect geophysical methods are more time- and cost-effective compared with the direct methods. The target of the geophysical investigations is to obtain an accurate image from the underground features. The Induced polarization (IP) is one of the common methods used for metal sulfide ore detection. Since metal ores are scattered in the host rock in the Zarshouran mine area, IP is considered as a major exploration method. Parallel to IP, the resistivity data gathering and processing are done to get a more accurate interpretation. In this work, we try to integrate the IP/RS geophysical attributes with borehole grade analyses and geological information using the cuckoo search machine-learning algorithm in order to estimate the silver grade values. The results obtained show that it is possible to estimate the grade values from the geophysical data accurately, especially in the areas without drilling data. This reduces the costs and time of the exploration and ore reserves estimation. Comparing the results of the intelligent inversion with the numerical methods, as the major tools to invert the geophysical data to the ore model, demonstrate a superior correlation between the results.
Seyed A. Mousavi; K. Ahangari; K. Goshtasbi
Abstract
Blast and stress release create cracks, fractures, and excavation damage zone in the remaining rock mass. Bench health monitoring (BHM) is crucial regarding bench health and safety in blast dynamic loading. Several empirical criteria have been proposed for a quick estimation of different parameters of ...
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Blast and stress release create cracks, fractures, and excavation damage zone in the remaining rock mass. Bench health monitoring (BHM) is crucial regarding bench health and safety in blast dynamic loading. Several empirical criteria have been proposed for a quick estimation of different parameters of a rock mass in the zone damaged by the blast. This work estimates the rock mass properties behind the blast hole based on the generalized Hoek-Brown failure criterion and quantitative disturbance factor (D). Considering a constant D value, either zero or one, for the entire rock mass, remarkably alters its strength and stability, resulting in very optimistic or very conservative analyses. Therefore, D is considered based on the elastic damage theory, and numerical simulation is conducted based on the finite difference software FLAC to investigate the vibration and damage threshold by monitoring the peak particle velocity (PPV) in the bench domain with different geometries. According to the numerical simulation, as the depth behind the blast hole increases, the value of D decreases from one to zero almost non-linearly, resulting in a non-linear reduction in the Hoek-Brown behavioral model properties. It is found that using various parameters of rock mass in the blast-induced damage zone behind the hole leads to thoroughly different PPV values than the constant parameters. Accordingly, the approach to using the quantified values of parameter D is of great importance in the estimation of various properties of a rock mass in the blast-induced zone, as well as calculation of the vibration.
Rock Mechanics
S. Ali Madadi; A. Majdi; M. H. Khosravi; A.R. Kargar
Abstract
Fracture mechanics is a vital component involved in studying the exact behavior of rock materials. Detection and assessment of the behavior of rock joints injected by grout plays an important role in numerical modelling in rock mechanic projects. The importance of mechanisms associated with initiation ...
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Fracture mechanics is a vital component involved in studying the exact behavior of rock materials. Detection and assessment of the behavior of rock joints injected by grout plays an important role in numerical modelling in rock mechanic projects. The importance of mechanisms associated with initiation and propagation of cracks due to hydraulic fracturing has led to a considerable interest in investigation and analysis of this phenomenon. In this work, the process of propagation of cracks on the wall of boreholes, drilled in single and bi-material structures, was simulated in ABAQUS software employing the extended finite element method. The energy method was implemented to obtain the stress intensity factor and energy release rate through applying J integral around the crack tip. The method was applied to two rock types, diorite and granite at the Chadormalu iron mine located in the central part of Iran. It was concluded that assuming the same geometry, the possibility of crack propagation at the boundary between two materials was more than the single material medium. Therefore, in dealing with a bi-material medium, if the purpose is to measure the in situ stresses, the measurement should not be performed on the boundary between the two materials.
Exploitation
S. Salarian; O. Asghari; M. Abedi; S. K. Alilou
Abstract
This work aims at figuring out the spatial relationships between the geophysical and geological models in a case study pertaining to copper-sulfide mineralization through an integrated 3D analysis of favorable target. The Ghalandar Skarn-Porphyry Cu Deposit, which is located in NW Iran, is selected for ...
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This work aims at figuring out the spatial relationships between the geophysical and geological models in a case study pertaining to copper-sulfide mineralization through an integrated 3D analysis of favorable target. The Ghalandar Skarn-Porphyry Cu Deposit, which is located in NW Iran, is selected for this research work. Three geophysical surveys of direct current electrical resistivity and induced polarization tomography along with magnetometry are performed to construct the physical properties of electrical resistivity, chargeability, and magnetic susceptibility, respectively. Inverse modeling and geostatistical interpolation are utilized to generate the physical 3D models. A 3D model of Cu grade is generated using ordinary kriging; however, the indicator kriging method is run to design a 3D model of rock types through incorporating the drilling results. Block models of geophysical and geological characteristics are cast in a similar 3D mesh to investigate their relationships in copper mineralization. A concentration-volume multi-fractal method is utilized to divide each model into its sub-sets, where the most productive portions in association with Cu-bearing mineralization are distinguished. Note that sub-sets of geophysical models are spatially matched with geological models of Cu grade and rock types. The zones with low electrical resistivity, high chargeability, and low magnetic susceptibility correspond to the main source of Cu mineralization in a dominated skarn rock type setting.
M. Mazraehli; Sh. Zare; M. Adebayo Idris
Abstract
The purpose of this work is to present an approach for the probabilistic stability analysis of tunnels considering the heterogeneity of geo-mechanical properties. A stochastic procedure is followed to account for the variability in the rock mass property characterization. The finite difference method ...
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The purpose of this work is to present an approach for the probabilistic stability analysis of tunnels considering the heterogeneity of geo-mechanical properties. A stochastic procedure is followed to account for the variability in the rock mass property characterization. The finite difference method is coupled with the Monte Carlo simulation technique to incorporate the randomness of rock mass properties. Moreover, a particular performance function is defined to investigate the excavation serviceability based on the permissible deformations. In order to validate the analysis, the probabilistic and the deterministic results are compared with the in-situ measurements. It can be observed that in both the probabilistic and deterministic analyses the largest displacements occur in the invert. In contrast, the smallest displacements are recorded in the sidewalls. Utilizing the performance function, the probability of failure for the invert, crown, left, and right wall is estimated as 100%, 68.8%, 16.2%, and 20.9%, respectively. Comparing the measured and calculated convergences, it is conjectured that the deterministic analysis underestimates the displacements, while the measured values are very close to the mean values predicted by the probabilistic analysis. The results obtained indicate that the presented approach could be a reliable technique compared to the conventional deterministic method.
Z. Piervandi; A. Khodadadi Darban; Seyed M. Mousavi; M. Abdollahi; Gh.R. Asadollahfardi; K. Akbari Noghabi
Abstract
Indigenous acidophilic bacteria separated from mine-waste can be used in return for the addition of the reagents like sulfuric acid. Among the tailings bacteria, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans are of the most-studied ones for the bioleaching and bioremediation of elements. ...
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Indigenous acidophilic bacteria separated from mine-waste can be used in return for the addition of the reagents like sulfuric acid. Among the tailings bacteria, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans are of the most-studied ones for the bioleaching and bioremediation of elements. In this work, the isolation and characterization of the mentioned bacteria are studied by a proposed biochemical protocol. The sequential cultivation of the soil bacteria in a series of liquid media and solid cult
Laleh Sohbatzadeh; Sied Ziaedin Shafaei Tonkaboni; Mohammad Noaparast
Abstract
In this research work, with a simple, safe, and environmentally friendly approach to hydrometallurgy, a method for the recovery of lithium (Li), cobalt (Co), and nickel (Ni) from LIBs is suggested. The cathode materials are leached by malonic acid, as the leaching agent, and ascorbic acid, as the reducing ...
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In this research work, with a simple, safe, and environmentally friendly approach to hydrometallurgy, a method for the recovery of lithium (Li), cobalt (Co), and nickel (Ni) from LIBs is suggested. The cathode materials are leached by malonic acid, as the leaching agent, and ascorbic acid, as the reducing agent in the first process, and by L-glutamic acid, as the leaching agent, and ascorbic acid, as the reducing agent in the second process. In order to optimize the leaching parameters including temperature, organic acid concentration, ascorbic acid concentration, type of organic acid, pulp density, and time, response surface methodology (RSM) of the experimental design process is used. According to the results, compared to L-glutamic acid in the second process, the leaching recovery increase considerably with malonic acid in the first process. This normally occurs due to the higher solubility of malonic acid in water, which results in a better complexation and a higher chelation rate. By contrast, as solubility of L-glutamic acid in water is low, metal-acid surface reaction and poor complexation are unavoidable. According to the statistical analysis of the results and validation testing, optimal experimental leaching occurs at the reaction temperature of 88 °C, organic acid concentration of 0.25 M, ascorbic acid concentration of 0.03 M, pulp density of 10 g/L, and leaching time of 2 h, via which metal recovery of 100% Li, 81% Co, and 99% Ni is achieved. Before and after acidic leaching, the sample active materials are qualitatively and quantitatively analyzed using X-ray diffraction, X-ray fluorescence, particle size analyzer, scanning electron microscope, energy dispersive spectroscopy, and atomic absorption spectroscopy.
Mohammad Rezaei; Milad Ghasemi
Abstract
Resource estimation and determining the grade distribution is one of the most important stages in planning and designing the open-pit and underground mines. In this work, a new mythology is used for resource estimation of the Angouran underground mine based on the optimized integration of the indicator ...
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Resource estimation and determining the grade distribution is one of the most important stages in planning and designing the open-pit and underground mines. In this work, a new mythology is used for resource estimation of the Angouran underground mine based on the optimized integration of the indicator kriging (IK), simple kriging (SK), and inverse distance weighted (IDW) methods. For this purpose, waste blocks are first removed from the block model using the IK method. Then the amount of mineral resource is estimated using the SK and IDW methods. Indeed, variograms are developed to estimate the grade of zinc minerals in the three used methods. Variograms analysis in three directions prove that the studied resource is anisotropic. Also the validation results confirm that the correlation coefficients between the measured and estimated zinc values by the SK and IDW methods equal to 0.76 and 0.75, respectively. Knowing this satisfactory result, a 3D model of the resource is prepared using the IK method, in which the ore and waste sections of the Angouran underground mine are separated definitely. According to the above methodology, the calculated resource of the Angouran underground mine using the SK method is achieved 1373962.5 tons with an average grade of 30.11%, whereas the estimated amount of this resource is attained 1349325 tons with an average grade of 31.88% using the IDW approach. The verification results show that the suggested methodology based on the optimized integration of the IK, SK, and IDW methods can be successfully applied for resource modeling and grade estimating of the Angouran underground mine.
