Mineral Processing
A. Abbasi Gharaei; B. Rezai; H. Hamidian Shoormasti
Abstract
According to the classification of the nickel laterite, this paper describes mineralogy test is to reveal where valuable elements are located in the ore, in which mineralogical form. The purpose of the sieving test was to study if some specific particle size contains most of the valuable metals. Based ...
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According to the classification of the nickel laterite, this paper describes mineralogy test is to reveal where valuable elements are located in the ore, in which mineralogical form. The purpose of the sieving test was to study if some specific particle size contains most of the valuable metals. Based on its chemical composition nickel laterite is classified as a limonite type and the nickel and cobalt content was 0.7 and 0.04%, respectively. Nickel is predominantly associated with hematite and goethite. Based on the mineralogical analysis of the ore, it is observed that remarkable part of nickel is located in hematite. Therefore, nickel cannot be released from hematite lattice. The nickel content in the laterite was 0.7% and the cobalt content 0.04%. The chemical composition of laterite equals with the occurrence of 38.9% iron oxides, 26.9% carbonates, 26.9% quartz, 4.8% chromite, 2.7% magnetite and 1.9% other minerals. EDS line profile analyses were completed on hematite/goethite ooids and there was a slight correlation in the quantities between iron and nickel in each individual ooid. However, iron and nickel do not always show a positive correlation. Nickel grade could be enriched from 0.7 wt.-percent to 0.91 wt.-percent; however nickel recovery was only 45%.
M. Hosseini; D. Fakhri
Abstract
The purpose of this work is to investigate the possibility of using mine wastes in the improvement of concrete properties. This research work investigates the physical and mechanical properties of the concrete specimens. These concrete specimens include concrete-lacking fibres, micro-silica and limestone ...
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The purpose of this work is to investigate the possibility of using mine wastes in the improvement of concrete properties. This research work investigates the physical and mechanical properties of the concrete specimens. These concrete specimens include concrete-lacking fibres, micro-silica and limestone powder (C), concrete-containing glass fibres without micro-silica and limestone powder (GC), concrete-containing micro-silica and limestone powder without fibres (CML), and concrete-containing glass fibres, micro-silica, and limestone powder (CGML). The physical and mechanical properties including the effective porosity, longitudinal wave velocity, water absorption, unit weight, tensile strength, uniaxial compressive strength, triaxial compressive strength, cohesion, and internal friction angle are investigated. The results obtained show that adding glass fibres to the concrete (GC) improve its properties compared to the fibre-less concrete (C). However, the properties of GC are improved significantly less than CGML. The Brazilian tensile strength and uniaxial compressive strength of GC increase by 13.6% and 10.95% relative to C. The Brazilian tensile strength and uniaxial compressive strength of CGML increase by 21.8% and 45.94% relative to C. Finally, it can be concluded that adding the micro-silica and limestone powder to the glass fibre concrete as well as the use of mine wastes also significantly improves the properties of the concrete.
M. Mohammadkhani; M. Abdollahy; M. R. Khalesi
Abstract
Copper oxide minerals such as malachite do not respond well to the traditional copper sulfide collectors, and require alternative flotation schemes. In many copper ore mines, significant copper oxide minerals, especially malachite, are associated with sulfide minerals. Considering that xanthates are ...
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Copper oxide minerals such as malachite do not respond well to the traditional copper sulfide collectors, and require alternative flotation schemes. In many copper ore mines, significant copper oxide minerals, especially malachite, are associated with sulfide minerals. Considering that xanthates are most widely used in the flotation of sulfide minerals as well as copper sulfide minerals and, hydroxamate has shown a good selectivity for copper oxide minerals. Use of the synergistic effect of xanthate and hydroxamate can be an effective way to increase the flotation efficiency of copper oxide minerals along with sulfide minerals. In this work, we investigate the individual interactions of potassium amyl xanthate (PAX) and potassium alkyl hydroxamate (HXM) with the natural malachite and explore their synergistic effects on the malachite flotation. The results of solubility of malachite in collector solutions, changes in the malachite surface potential, adsorption kinetics, adsorption densities, dynamic contact angles, FT-IR analyses, and small-scale flotations, are discussed. The results obtained demonstrate that PAX and HXM are chemically co-adsorbed on the malachite surface, and the amount of PAX adsorbed on the malachite surface is considerably increased in the mixed PAX/HXM systems because of the co-adsorption mechanism. The flotation results confirm that the mixed PAX/HXM exhibit a superior flotation performance of malachite compared to the individual system of PAX or HXM. Based on these results, the mixed PAX/HXM exhibit a remarkable synergism effect on malachite surface hydrophobicity.
R. Dabiri; E. Amiri Shiraz
Abstract
This paper describes a preliminary study of the adsorption of toxic elements from synthetic wastewater in a batch mode. Clay minerals have been highly considered as inexpensive available adsorbents that adapt with the environment due to a special level and a high potential of adsorption. In the present ...
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This paper describes a preliminary study of the adsorption of toxic elements from synthetic wastewater in a batch mode. Clay minerals have been highly considered as inexpensive available adsorbents that adapt with the environment due to a special level and a high potential of adsorption. In the present research work, low-cost natural minerals of speiolite from the Iliato mine (located in NE Iran) and zeolite from the Aftar mine (located in north of Iran) are used to remove nickel(II), antimony(III), and arsenic(V) from synthetic wastewater. The adsorption experiments are conducted by varying the initial concentrations of the elements, pH values, adsorption times, and adsorbent dosage. The experimental isotherm data is analyzed using the Langmuir and Freundlich equations. Concerning a higher Langmuir coefficient R2 in nickel and antimony, the mechanism of adsorption of these elements is mono-layer and homogenous. Based on the Freundlich model, adsorption of arsenic is multi-layer and heterogeneous. The kinetic studies show that the Ni, Sb, and As adsorption mechanism is well-described by a pseudo-second-order kinetic model. The thermodynamic parameters indicate that the adsorption process has an exothermic character and is more feasible with decreasing temperature. Based on the experimental results, it can be concluded that natural sepiolite and zeolite has the potential of application as an efficient adsorbent for the removal of toxic elements from synthetic wastewater.
Rock Mechanics
M. Lotfi; B. Tokhmechi
Abstract
Nowadays, Barton’s Joint Roughness Coefficients (JRC) are widely used as the index for roughness and as a challenging fracture property. When JRC ranking is the goal, deriving JRC from different fractal/wavelet procedures can be conflicting. Complexity increases when various rankings outcome from ...
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Nowadays, Barton’s Joint Roughness Coefficients (JRC) are widely used as the index for roughness and as a challenging fracture property. When JRC ranking is the goal, deriving JRC from different fractal/wavelet procedures can be conflicting. Complexity increases when various rankings outcome from different calculation methods. Therefore, using Barton’s JRC, we cannot make a decision based on the proven mathematical theories because each method has a different rank. Ideally, these rankings must be equal but, in practice, they are different for each method. To solve this problem and to achieve a robust and valid ranking for JRC, Condorcetand Borda count methods have been used. These methods have been proposed as fusion approaches. Re-ranking of JRC using different methods integrated with Condorcet showed confusion in ranking of the JRC4, JRC5, and JRC6 profiles. This ambiguity is equal to equalizing decision conditions about all the three at the examination of the winners, losers, and draws in pairwise matrices. Therefore, Borda Count was applied and resulted in robust rankings. In fact, a new approach for a roughness measurement is presented. A new JRC ranking called JRCN is introduced. This new ranking shows a lower sum of squared errors (0.00390) in comparison with the original JRC ranking method (0.00410) and ranked JRCN1 to JRCN10. Thus it is proposed to consider JRCN as a new and improved version of JRC rankings.
R. Alizadeh; M. Fatehi Marji; A. Abdollahipour; M. Pourghasemi Sagand
Abstract
In this work, an effective methodology is introduced for modeling the fatigue crack propagation in linear elastic brittle media. The displacement discontinuity method is used to accomplish the analysis, and the boundaries are discretized with quadratic elements in order to predict the stress intensity ...
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In this work, an effective methodology is introduced for modeling the fatigue crack propagation in linear elastic brittle media. The displacement discontinuity method is used to accomplish the analysis, and the boundaries are discretized with quadratic elements in order to predict the stress intensity factors near the crack tips. This procedure is implemented through 2D linear elastic fracture mechanics. The normal and shear displacement discontinuity around the crack tip is applied to compute the mixed-mode stress intensity factors. The crack growth is incremental, and for each increment of extension, there is no need to use a re-meshing procedure. This method has benefits over the finite element method due to its simplicity in meshing. The crack growth direction is assessed using the maximum principal stress theory. In these analyses, a repetition method is used in order to estimate the correct path of crack propagation. Therefore, the different lengths of incremental growth do not affect the crack growth path analysis. The results are exhibited for several examples with different geometries to demonstrate the efficiency of the approach for analyzing the fatigue crack growth. The accuracy represents that this formulation is ideal for describing the fatigue crack growth problems under the mixed-mode conditions.
H. Sarfaraz
Abstract
One of the most conventional toppling instabilities is the block-flexural toppling failure that occurs in civil and mining engineering projects. In this kind of failure, some rock columns are broken due to tensile bending stresses, and the others are overturned due to their weights, and finally, all ...
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One of the most conventional toppling instabilities is the block-flexural toppling failure that occurs in civil and mining engineering projects. In this kind of failure, some rock columns are broken due to tensile bending stresses, and the others are overturned due to their weights, and finally, all of the blocks topple together. A specific feature of spheroidal weathering is the rounding of the rock column edges. In the mode of flexural toppling failure, rounding of edges happens only at the upper corners of the block but in the block toppling failure mode, due to the presence of cross-joints at the base of the block, rounding of edges also occurs at the base of the block. In this work, a theoretical model is offered to block-flexural toppling failure regarding the erosion phenomenon. The suggested methodology is evaluated through a typical example and a case study. The results of this research work illustrate that in the stable slopes with rectangular prismatic blocks, where the safety factor value is close to one, the slope is subjected to failure due to erosion. Also the results obtained show that the recommended approach is conservative in analyzing the block-flexural toppling failure, and this approach can be applied to evaluate this failure.
Saeed Saadat
Abstract
In this work, the results of nearly 1400 stream sediment sample analysis are processed to better understand environmental pollution caused by mining activities in Eastern Iran. The stream sediment samples are analyzed for As, Sb, Fe, Cr, Ni, Co, Cu, Zn, Pb, Sr, and Hg. The mean concentration of these ...
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In this work, the results of nearly 1400 stream sediment sample analysis are processed to better understand environmental pollution caused by mining activities in Eastern Iran. The stream sediment samples are analyzed for As, Sb, Fe, Cr, Ni, Co, Cu, Zn, Pb, Sr, and Hg. The mean concentration of these elements follows the decreasing order of Fe > Sr > Zn > Cr > Cu > Ni > Co > Pb > As > Sb > Hg. Based on the assessment of pollution, extremely severe enrichment factor Co (EF > 25), and high enrichment of Sb, Hg, Cr, and Sr (EF > 10) are detected. Specifically, Cr and Ni in southern stream sediments show significantly elevated concentrations compared to the others. The range of the contamination factor varies from CF < 1 to CF > 6 for most elements. Geo-accumulation index shows high contamination levels by Cr and Co and high to severe contamination by Sb. The risk indices are low for all elements except for As and Co in the eastern part of the studied area. Principal component analysis, Spearman correlation coefficient, and cluster analysis are used to demonstrate similarities and differences between the elements. Pollution indices show that contaminations in some samples are the consequence of gold mineralization. The high correlation of Cu, Zn, and Sb is due to the sulfide mineralization of gold. The high correlation of Cr and Ni corresponds to ultramafic rocks and ophiolitic series. This study focuses on the impact of mining activities, even at early stages on the dispersion of some heavy metals in stream sediments. Based on the results presented here, while most contamination in the target area is rooted in geochemical and mineralization processes, mining activity also contributes to soil pollution for certain elements such as Cu and Zn. The most affected stream sediments are those within the vicinity of mining areas and attention should be paid to potential risks to the environment particularly during gold mining activities.
Ali Nouri Qarahasanlou; Alireza Dolatshahi
Abstract
Engineers use various methods to evaluate the performance of concrete structures under dynamic loads, including numerical simulations, laboratory experiments, and field tests. By combining the results of these methods, the engineers can develop a comprehensive understanding of the behavior of concrete ...
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Engineers use various methods to evaluate the performance of concrete structures under dynamic loads, including numerical simulations, laboratory experiments, and field tests. By combining the results of these methods, the engineers can develop a comprehensive understanding of the behavior of concrete structures under dynamic loads and use this information to design more resilient structures capable of withstanding these loads. In this work, four models of the concrete lining of the circular tunnel are simulated to investigate the effect of the pre-cracked in the tunnel's concrete lining under an internal explosion loading. A crack in three different locations at angles of 0, 45, and 90 on the horizontal axis of the tunnel is investigated and analyzed. The coupled Eulerian-Lagrangian method and the constitutive behavior, such as concrete damage plasticity for concrete and Drucker-Prager for soil, allows a more accurate simulation of the internal explosion loading scenario. The selection of Trinitrotoluene and the Jones-Wilkins-Lee equation of state for the explosive provides a realistic representation of the behavior of the explosive material. The modeling results show that in an internal explosion, by examining three different locations of a crack in the concrete, the occurrence of a crack in the crown of the tunnel is more critical than two crack locations. Hence, the existence of a crack with a length of 100 cm and a depth of 15 cm in the crown of the tunnel increases the tensile damage zone by 16.59% compared to the case where there is no crack.
K. Tanguturi; R. Balusu
Abstract
Fundamental understanding of the goaf gas distribution in a gassy coal mine is necessary for developing effective goaf gas drainage strategies in the longwall coal mine. The goaf gas was subjected to the surface and body forces that were classified depending upon whether they acted on the surface area ...
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Fundamental understanding of the goaf gas distribution in a gassy coal mine is necessary for developing effective goaf gas drainage strategies in the longwall coal mine. The goaf gas was subjected to the surface and body forces that were classified depending upon whether they acted on the surface area or the volume of the gas element. Of these forces, the body forces were more predominant in displacing the goaf gas present in the underground mine. The buoyancy forces were classified as the body forces; they are the predominant forces acting on the goaf gas. The buoyancy forces depend mainly upon the density variation in the gas species and the panel orientation or panel geometry. If the temperature variations are neglected, the buoyancy forces that cause the displacement of the goaf gas depend mainly upon the panel orientation. In this work, numerical investigations were carried out using the computational fluid dynamics (CFD) techniques for the fundamental understanding of the goaf gas displacement for various panel orientations. The numerical results obtained for various panel orientations indicated that the goaf gas is displaced towards the tailgate (TG) side when the maingate (MG) was downdip, towards the MG side when MG was updip, towards the start-up of the panel when the face was downdip, and towards the face when the face was updip.
Mineral Processing
S. Nazari; Seyed Ziaedin Shafaei; M. Gharabaghi; R. Ahmadi; B. Shahbazi
Abstract
In this work, the effects of the types of frother (MIBC, pine oil, and A65) and operational parameters (impeller speed and air flow rate) on the flotation of quartz coarse particles was investigated using nano bubbles (NBs). Quartz particles of the size of -425+106 mm and three types of frother were ...
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In this work, the effects of the types of frother (MIBC, pine oil, and A65) and operational parameters (impeller speed and air flow rate) on the flotation of quartz coarse particles was investigated using nano bubbles (NBs). Quartz particles of the size of -425+106 mm and three types of frother were used for the flotation experiments. Also the impeller speed was 600 to 1300 rpm, and the air flow rates were 30 and 60 L/h. In the absence of NBs, the maximum recovery was achieved with the pine oil frother, an impeller speed of 1000 rpm, and an air flow rate of 60 L/h. In the presence of NBs, the maximum recovery was achieved using pine oil at an impeller speed of 900 rpm and an air flow rate of 30 L/h. However, increasing the recovery in the presence of NBs, compared to the absence of NBs for MIBC, was more than the other two frothers, and the recovery using this frother to increase up to 25% but using pine oil, the recovery increased up to 23%. The lowest recovery in the presence of NBs was obtained using A65. Also the use of NBs increased recovery in all the three fractions compared to the absence of NBs but the presence of NBs increased the recovery of particles with size of -212+106 mm more than the particle size in the ranges of -300+212 and -425+300 mm.
A. Ghasemloonia; S. D. Butt
Abstract
Underground caverns in rock salt deposits are the most secure disposal method and a type of gas-storing facility. Gas storage plays a vital role in ensuring that a strategic relationship is secured between an established energy infrastructure provider and a midstream energy company. The Fischells Brook ...
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Underground caverns in rock salt deposits are the most secure disposal method and a type of gas-storing facility. Gas storage plays a vital role in ensuring that a strategic relationship is secured between an established energy infrastructure provider and a midstream energy company. The Fischells Brook area is a pillow-shaped body of salts located in the St. George's Bay area of southwest Newfoundland, which has three layers of salt beds, and is capable of excavating caverns for the storage purposes. The development of cavern facilities requires the stability analysis through numerical models and experimental facilities. This work was motivated to examine the engineering feasibility of the salt cavern characteristics in this area, and to investigate its stability under creep behavior. An experimental test facility was developed to investigate the constitutive parameters governing the creep of rock salt, and the constitutive parameters were implemented into a developed finite element model to investigate the stability of the cavern over a 5-year period. Also a stress-based dilatancy failure envelope was developed to interpret the results of the numerical model, and to conduct sensitivity analyses for different design scenarios. The design recommendations developed in this study will be implemented as a key part of an engineering feasibility study for underground caverns in salt deposits in western Newfoundland.
H. Shahi; R. Ghavami Riabi; A. Kamkar Ruhani; H. Asadi Haroni
Abstract
In this research work, the frequency domain (FD) of surface geochemical data was analyzed to decompose the complex geochemical patterns related to different depths of the mineral deposit. In order to predict the variation in mineralization in the depth and identify the deep geochemical anomalies and ...
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In this research work, the frequency domain (FD) of surface geochemical data was analyzed to decompose the complex geochemical patterns related to different depths of the mineral deposit. In order to predict the variation in mineralization in the depth and identify the deep geochemical anomalies and blind mineralization using the surface geochemical data for the Dalli Cu-Au porphyry deposit, a newly developed approach was proposed based on the coupling Fourier transform and principal component analysis. The surface geochemical data was transferred to FD using Fourier transformation and high and low pass filters were performed on FD. Then the principal component analysis method was employed on these frequency bands separately. This new combined approach demonstrated desirably the relationship between the high and low frequencies in the surface geochemical distribution map and the deposit depth. This new combined approach is a valuable data-processing tool and pattern-recognition technique to identify the promising anomalies, and to determine the mineralization trends in the depth without drilling. The information obtained from the exploration drillings such as boreholes confirms the results obtained from this method. The new exploratory information obtained from FD of the surface geochemical distribution map was not achieved in the spatial domain. This approach is quite inexpensive compared to the traditional exploration methods.
M. Shamsi; M. Noparast; Seyyed Z. Shafaie; M. Gharabaghi; S. Aslani
Abstract
Copper smelting slags are hard materials. Therefore,to recover their copper by flotation method, grinding should be carried out to obtain optimal particle size. Copper smelting slags in the Bardeskan district, with work index of 16.24 kwh/st, were grinded for 65 minutes to reach an acceptable degree ...
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Copper smelting slags are hard materials. Therefore,to recover their copper by flotation method, grinding should be carried out to obtain optimal particle size. Copper smelting slags in the Bardeskan district, with work index of 16.24 kwh/st, were grinded for 65 minutes to reach an acceptable degree of freedom for the flotation tests, with particle size of 80%, smaller than 70 μm. With this grinding time, degree of freedom for copper-bearing minerals was achieved 85-90%. The floatation method performed and the procedure used for the optimization of the effective parameters were described in this paper. The results obtained for the flotation tests, carried out at the optimal conditions after grinding the slags (with a grinding time of65 minutes), showed 62.23% of copper recovery, while, by flotation of copper slags at optimal conditions after increasing the grinding time to 85 minutes (d80 = 48µ), the Cu recovery was increased to 79.89%.
M. Otari; R. Dabiri
Abstract
Heavy metal concentration in the soils and sediments has increased worldwide during the last century due to the mining, smelting, and industrial activities. The Forumad chromite deposit is located in the Sabzevar ophiolitic complex (SOC), with a long history of mining activities, yet very little is known ...
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Heavy metal concentration in the soils and sediments has increased worldwide during the last century due to the mining, smelting, and industrial activities. The Forumad chromite deposit is located in the Sabzevar ophiolitic complex (SOC), with a long history of mining activities, yet very little is known about the heavy metal contamination in its surrounding environment. In this research work, the soil pollution by heavy metals was investigated with respect to the geochemical, statistical, and environmental indicators over the chromite mine in Forumad. The concentrations of heavy metals were analyzed, and the results obtained showed that the mean concentrations of Cr (5837.5 ppm) and Ni (570.7 ppm) in the nearby soils and sediments were significantly high. On the other hand, the mean concentrations of the other heavy metals present such as As, Cd, Co, Cu, Pb, and V were close to the geological background values. The multivariate statistical analyses (Pearson coefficient analysis, Cluster analysis, and principal component analysis) were used to understand the various anthropogenic and geological (lithogenic) sources. Our geochemical and environmental assessments suggested that Cr, Ni, Co, and V had similar properties, and their presence in the soils was mainly from the ultramafic rocks and chromite deposits. However, the calculated enrichment factors for Cr and Ni were more than 10, suggesting their anthropogenic sources due to the mining activities. The significant Cr and Ni contaminations in the Forumad nearby soils indicated that the status of heavy metal contaminations of the area should receive further considerations in the metal mine areas throughout SOC.
Seyyed M. Seyyed Alizadeh Ganji; S. Z. Shafaie; N. Goudarzi
Abstract
This work was aimed to evaluate and compare the performances of the solvents D2EHPA (Di-(2-ethylhexyl) phosphoric acid), Cyanex 272 (bis (2,4,4-trimethylpentyl) phosphinic acid), and a mixture system of D2EHPA and Cyanex272 in the separation of some rare earth elements (REEs) including lanthanum, gadolinium, ...
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This work was aimed to evaluate and compare the performances of the solvents D2EHPA (Di-(2-ethylhexyl) phosphoric acid), Cyanex 272 (bis (2,4,4-trimethylpentyl) phosphinic acid), and a mixture system of D2EHPA and Cyanex272 in the separation of some rare earth elements (REEs) including lanthanum, gadolinium, neodymium, and dyspersym from a nitric acid solution. The results obtained showed that Cyane272 had the lowest separation factor in the separation of Dy, La, Nd, and Gd from each other. Also it was found that a mixture system of D2EHPA and Cyanex272 had the best performance in the separation of the investigated REEs, owing to the higher separation factors for Dy/Nd and Dy/Gd, as well as the lower extraction efficiencies for Gd (64.54%), La (30.07%), and Nd (26.47) from Dy (99.92). It was also determined that the separation factors forDy/Nd and Dy/Gd were 720.05 and 3640.27, respectively, using their mixture system.
R. Mikaeil; M. Abdollahi Kamran; G. Sadegheslam; M. Ataei
Abstract
Predicting the sawability of the dimension stone is one of the most important factors involved in production planning. Moreover, this factor can be used as an important criterion in the cost estimation and planning of the stone plants. The main purpose for carrying out this work was to rank the sawability ...
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Predicting the sawability of the dimension stone is one of the most important factors involved in production planning. Moreover, this factor can be used as an important criterion in the cost estimation and planning of the stone plants. The main purpose for carrying out this work was to rank the sawability of the dimension stone using the PROMETHEE method. In this research work, four important physical and mechanical properties of rocks including the uniaxial compressive strength, Schmiazek F-abrasivity, mohs hardness, and Young's modulus were evaluated as the criteria. During the research process, two groups of dimension stones were selected and analyzed. The rock samples were collected from a number of Iranian factories for the laboratory tests. The production rate of each sawn stone was selected to verify the proposed sawability ranking method. The results obtained showed that the new ranking method can be reliably used for evaluating the sawability of the dimension stone at any stone factory with different rocks only by the physical and mechanical properties testing.
M. Sakizadeh; R. Mirzaei
Abstract
The aim of this work is to examine the feasibilities of the support vector machines (SVMs) and K-nearest neighbor (K-NN) classifier methods for the classification of an aquifer in the Khuzestan Province, Iran. For this purpose, 17 groundwater quality variables including EC, TDS, turbidity, pH, total ...
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The aim of this work is to examine the feasibilities of the support vector machines (SVMs) and K-nearest neighbor (K-NN) classifier methods for the classification of an aquifer in the Khuzestan Province, Iran. For this purpose, 17 groundwater quality variables including EC, TDS, turbidity, pH, total hardness, Ca, Mg, total alkalinity, sulfate, nitrate, nitrite, fluoride, phosphate, Fe, Mn, Cu, and Cr(VI) from 41 wells and springs were used during an eight-year time period (2006 to 2013). The cluster analysis was used, leading to a dendrogram that differentiated two distinct groups. The factor analysis extracted eight factors accumulatively, accounting for 90.97% of the total variance. Thus the variations in 17 variables could be covered by just eight factors. K-NN and SVMs were applied for the classification of the aquifer under study. The results of SVMs indicated that the best performed model was related to an exponent of degree one with an accuracy of 94% for the test data set, in which the sensitivity and specificity were 1.00 and 0.87, respectively. In addition, there was no significant difference among the results of different kernels, indicating that an acceptable result can be achieved by selecting the optimum parameters for a kernel. The results of K-NN showed roughly a lower efficiency compared with those of SVMs, where the sensitivity and specificity was reduced to 0.90 and 0.88, respectively, although the accuracy of the model was 93%. A sensitivity analysis was performed on the groundwater quality variables, suggesting that calcium next to nitrate were the most influential parameters in the classification of this aquifer.
I. Montazeri; M. Taji
Abstract
Various traditional and industrial coke making techniques were discussed based on their limitations and production capacities, and the criteria such as the quality and size of coke production, amount of coke crumb, amount of investment, amount of operational costs, labor force and mechanization. In this ...
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Various traditional and industrial coke making techniques were discussed based on their limitations and production capacities, and the criteria such as the quality and size of coke production, amount of coke crumb, amount of investment, amount of operational costs, labor force and mechanization. In this work, the rankings of various traditional and industrial coke making techniques were carried out using a multi-criteria decision making with technique for order preference by similarity to ideal solution (TOPSIS), in which, at first, industrial heat recovery coke oven, by product coke oven and non-recovery coke oven and then traditional bee-hive coke making was performed in Shahrood Simin Coke Company. The designed oven decreased both the environmental pollution and the amount of coke crumb, and increased the coke production and coke recovery qualities.
H. Dehghani; N. Mikhak Beiranvand
Abstract
One of the most important parameters used for determining the performance of tunnel boring machines (TBMs) is their penetration rate. The parameters affecting the penetration rate can be divided in two categories. The first category is the controllable parameters such as the TBM technical characteristics, ...
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One of the most important parameters used for determining the performance of tunnel boring machines (TBMs) is their penetration rate. The parameters affecting the penetration rate can be divided in two categories. The first category is the controllable parameters such as the TBM technical characteristics, and type and geometry of the tunnel, and the second one is the uncontrollable parameters such as the intact rock properties and characteristics of the rock mass discontinuities. The aim of this work was to investigate the effects of rock mass properties on the penetration rate, and to present a new mathematical equation based on a statistical approach to estimate the TBM performance. To achieve this aim, the Monte-Carlo (MC) simulation method was used to model the TBM performance. Accordingly, the database consisting of the rock mechanics information such as the uniaxial compressive strength, Brazilian tensile strength, toughness and hardness of rock, spacing and orientation of discontinuities, and measured TBM penetration rate in 151 points out of a water tunnel was collected. Next, using the dimensional analysis, a comprehensive mathematical equation was obtained to calculate the TBM penetration rates using the developed database. Finally, using the MC simulation method, the probability distribution function of the TBM penetration rate was studied. The validation results obtained showed that the root mean square error (RMSE) of the proposed relationship was less than 0.3. The MC simulation results showed that hardness and density had the most and least effects on the penetration rate, respectively.
M. Ataei; E. Tajvidi Asr; R. Khalokakaie; K. Ghanbari; M. R. Tavakoli Mohammadi
Abstract
Environmental impact assessment (EIA) has led to the dominance of planners on the natural environment of the regions, providing the possibility of continuously monitoring and controlling the status quo by management staff. In this regard, a new semi-quantitative model is presented for the EIA of the ...
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Environmental impact assessment (EIA) has led to the dominance of planners on the natural environment of the regions, providing the possibility of continuously monitoring and controlling the status quo by management staff. In this regard, a new semi-quantitative model is presented for the EIA of the Eastern Alborz Coal Mining complex using the matrix method, and determining the corresponding impacting factors and environmental components. For this purpose, the expert opinions are used to gather the preliminary data and score the parameters involved. The effect of each impacting factor involved on each environmental component is determined by quantifying the qualitative comments. According to the results obtained, the components air quality, human health and safety, and ecology and soil of the area undergo the most environmental damages from the mining activities. Then the EIA results obtained are used to assess the sustainability of the complex using the Phillips mathematical model. The results obtained indicate that the sustainability of this complex is weak, and, therefore, the preventive environmental measures with a preference must be recommended to reduce the environmental damages to its components.
M. Moghise; M. Pourrahim; B. Rezai; M. Gharabaghi
Abstract
This study aims to investigate and optimize the effects of the main parameters including the particle size, gravity and magnetic separation combination, high gradient magnetic separation, magnetic field intensity, shaking table slope, washing water flow, and electrostatic separation upon the rare earth ...
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This study aims to investigate and optimize the effects of the main parameters including the particle size, gravity and magnetic separation combination, high gradient magnetic separation, magnetic field intensity, shaking table slope, washing water flow, and electrostatic separation upon the rare earth element (REE) recoveries from iron mine waste. The electron microprobe showed that high amounts of REEs were distributed on the fluorapatite mineral, and hence, it was necessary to remove the high magnetic minerals by a low-intensity magnetic separation using a magnetic drum in an experimental procedure. A cyclic magnetic separator was used for the low-gradient magnetic separation. Moreover, a shaking table and an electrostatic separator were used to expand the recovery and grade of REEs. A combination of these methods was considered to optimize the REE recoveries based on the best combination including two steps of low magnetic separation, one step of medium intensity magnetic separation, a shaking table, and an electrostatic separator. Two low-intensity magnetic of 800 and 2000 gauss, one medium-intensity magnetic of 8000 gauss, a one-step shaking table with a water flow of 90 mL/s and a table slope of 3 degree, and one electrostatic separator of 25000 V with a blade angel of 20 degree had the best performance to separate REEs. The microscopic studies carried out showed that the monazite degree of freedom was between 75 and 105 micron. The results obtained showed that a particle size of ‒75 + 63 micron was a proper one to separate REEs. The total recovery and grade of the REE (Ce, La, Nd, Er, and Gd) concentrate obtained from the sample with a grade of 1499 ppm of REEs were 67.1 and 1.2%, respectively, at the optimum conditions. The results obtained showed that there was a direct relation between the phosphor grade and the REE recoveries, and that the REE recoveries increased by increasing the quantity of phosphor.
S. Moghaddam; S. Dezhpasand; A. Kamkar Rohani; S. Parnow; M. Ebrahimi
Abstract
Protection of water resources from contamination and detection of the contaminants and their treatments are among the essential issues in the management of water resources. In this work, the time-lapse electrical resistivity tomography (ERT) surveys were conducted along 7 longitudinal lines in the downstream ...
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Protection of water resources from contamination and detection of the contaminants and their treatments are among the essential issues in the management of water resources. In this work, the time-lapse electrical resistivity tomography (ERT) surveys were conducted along 7 longitudinal lines in the downstream of the Latian dam in Jajrood (Iran), in order to detect the contamination resulting from the direct injection of a saltwater solution in to the saturated zone in the area. To investigate the pollutant quantities affecting the resistivity of this zone, the temperature and electrical conductivity measurement were carried out using a self-recording device during 20 days (before and after the injection). The results obtained from the self-recording device measurements and ERT surveys indicated that in addition to the salt concentration changes in water, the resistivity changes in the saturated zone were dependent on other factors such as the lithology and absorption of contaminants by the subsurface layers. Furthermore, the expansion of contamination toward the geological trend, sedimentation, and groundwater flow direction of the area were shown.
A. Abdollahipour; M. Fatehi Marji; A. R. Yarahmadi Bafghi; J. Gholamnejad
Abstract
Hydraulic fracturing (HF), as a stimulation technique in petroleum engineering, has made possible the oil production from reservoirs with very low permeability. The combination of horizontal drilling and multiple HF with various perforation angles has been widely used to stimulate oil reservoirs for ...
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Hydraulic fracturing (HF), as a stimulation technique in petroleum engineering, has made possible the oil production from reservoirs with very low permeability. The combination of horizontal drilling and multiple HF with various perforation angles has been widely used to stimulate oil reservoirs for economical productions. Despite the wide use of HF, there are still ambiguous aspects that require more investigation. Therefore, optimizing the geometry of the initial fractures using numerical methods is of high importance in a successful HF operation. Different geometrical parameters of the initial HF cracks including patterns, spacings, crack lengths, and perforation phase angles were modeled using the higher order displacement discontinuity method (HODDM) in horizontal and vertical oil wells. Several well-known issues in HF such as crack interference and crack arrest were observed in certain patterns of the HF cracks. Also the best possible arrangements of the HF cracks were determined for a better production. The results obtained were verified by the in-situ measurements existing in the literature. In addition, the best perforation phase angle in vertical wells was investigated and determined.
M. Mokhtarian Asl; J. Sattarvand
Abstract
Production planning of an open-pit mine is a procedure during which the rock blocks are assigned to different production periods in a way that leads to the highest net present value (NPV) subject to some operational and technical constraints. This process becomes much more complicated by incorporation ...
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Production planning of an open-pit mine is a procedure during which the rock blocks are assigned to different production periods in a way that leads to the highest net present value (NPV) subject to some operational and technical constraints. This process becomes much more complicated by incorporation of the uncertainty existing in the input parameters. The commodity price uncertainty is among the most significant factors, whose effects cannot be mitigated through further exploration or investigation. The present work introduced a new approach for integration of the commodity price uncertainty into long-term production planning of open-pit mines. The procedure involves solving the problem by the integer programming method based on a series of economic block models that are realized based on the sampled prices from commodity price distribution function using the median Latin hypercube sampling method. The results obtained showed that the new methodology is able to reduce the risks and the net present value of the new approach at a confidence level 80% more than the conventional methods.
