Journal of Mining and EnvironmentJournal of Mining and Environment
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Feed provided by Journal of Mining and Environment. Click to visit.Gold, Silver and Iron in Iron Oxy-hydroxide Precipitate Formed in Process of Acid Mine Drainage
http://jme.shahroodut.ac.ir/article_1689_195.html
Oxidation of sulfide-containing ores is the main cause of Acid Mine Drainage (AMD), which is an environmental problem associated with both the abandoned and active mines. Iron-bearing sulfide minerals can be oxidized and form mine waters with high sulfate content, low pH, high electrical conductivity, high redox potential, and high concentrations of iron, aluminum, and other heavy metals. In the process of AMD, precipitation of poorly crystalized oxy-hydroxides of iron with a large active surface can occur. On the surface of iron oxy-hydroxide, the precipitated particulate matter, anions, and cations (metals) could be adsorbed. Mine waters can contain a certain amount of precious metals that can also be adsorbed onto an iron particulate matter surface, which is investigated in this research work. In this work, the samples of iron oxy-hydroxide particulate matter at abandoned gold mine waste in Bakovići (Central Bosnia and Herzegovina) are used. Several parameters including pH, water content, particle size distribution, sulfate content, electrical conductivity, redox potential, and amounts of gold, silver, and iron are measured on the selected mine waste samples. The results obtained indicate that significant amounts of gold (average: 6.8 mg/kg) and silver (average: 7.13 mg/kg) are present in the iron precipitate. Adsorption of precious metals onto the iron oxy-hydroxide surface is strongly pH-dependent. At a very low pH value, desorption of precious metals is favorite. Thus, precious metals are only partially adsorbed onto the iron oxy-hydroxide surface.Tue, 31 Mar 2020 19:30:00 +0100Mining and Environmental Degradation: a Gift Brings Grief Scenario for Mining Communities in ...
http://jme.shahroodut.ac.ir/article_1694_195.html
Sierra Leone is blessed with abundant natural resources but yet prone to environmental degradation due to the mining operations. Most often, the mining communities are faced with social tensions, as a result of the possible trade-off between the expected employment impact and the cost of mining operations to the environment. Over the past decades, the contribution of the mining sector to the development of the country has been overshadowed by the fact that the mining operations have had adverse negative effects, mainly due to the country's weak environmental policies and the failure of the mine monitoring institutions, to supervise the operations of mining company operations. This article seeks to examine both the environmental and the social implication of mining operations on three mining edge communities in Sierra Leone. This paper also utilizes secondary data from the published articles, government’s reports, workshops and conference proceedings, policy documents of non-governmental organizations, newspapers, and the like to generate this writer's view on the topic under review. The thrust of the review will be on the following: Sierra Rutile Limited, Koidu Holdings Limited, and Shandong Iron Ore Mines. The above mining companies have been carefully selected due to the fact that they are located close to dwelling communities, and have been mining in Sierra Leone over a long period of time. The environmental performance index and the mining impact framework are used to clearly show the impact of mining operations on the environment in Sierra Leone. As a result of mining operations, deforestation is skyrocketing, public discomfort and air pollution has worsened, and social unrest has increased as a result of some unacceptable consequences including pollution of water source without recourse to short-term remedy. The literature reviewed by this writer reveals that the mining activities have two faces in Sierra Leone. One is that it serves as a resource curse. An example to this sad reality is the outbreak of civil war, social unrest among others. On the other hand, the mining sector is one of the principal backbones of the economy. It contributes to the livelihood of the country. This paper introduces three-way approaches of mining sector operation remedies that include but not limited to: 1) sound Environmental Impact Assessment (EIA) adoption before mining operations starts; 2) carrying out Strategic Environmental Assessment (SEA); 3) regular engagement with all stakeholders of mining-affected communities. This article recommends that restoration activities by mining companies go along with extraction and adequate compensation.Tue, 31 Mar 2020 19:30:00 +0100A Safe and Sustainable Development in a Hygiene and Healthy Company Using Decision Matrix Risk ...
http://jme.shahroodut.ac.ir/article_1714_195.html
This article describes the process of improving risk management practices in a foundry of the ALFET Company (Algeria). The proposed methodology is based on the decision matrix risk assessment technique. This technique allows making a risk assessment for each source of risk (machine, man, environment, and management), which leads to the determination of the overall risk rate during the activity by a new concept. The latter giving a comprehensive vision of occupational health and safety, and compares it with the ALARP principle to determine the acceptability of risk. The main goal of this work is to inculcate a culture on the effects of changing behaviors and attitudes, to disseminate the culture of continuous and sustainable progress within the enterprise, and to ensure that a good atmosphere is maintained in the workplace. It aims to protect and promote the health and safety of workers and the working environment in order to promote a safe and sustainable development company. Our work shows that the working environment is tolerable in terms of health and safety at work. However, to promote a safe and sustainable development in company, an action plan based on the evaluation of the field and feedback through priority actions is recommended for continuous improvement in OSH. Toward the workplace should be continuously monitored to detect risk factors as early as possible before they have negative effects.Tue, 31 Mar 2020 19:30:00 +0100Development of Geometallurgical Indices for Semi-Autogenous Grinding at Sarcheshmeh Porphyry ...
http://jme.shahroodut.ac.ir/article_1669_195.html
Geometallurgy tries to predict the instability the behavior of ores caused by variability in the geological settings, and to optimize the mineral value chain. Understanding the ore variability and subsequently the process response are considered to be the most important functions of an accurate geometallurgical study. In this paper, the geometallurgical index is presented as a new tool to optimize the mining activities. Geometallurgical index is described as any geological feature that makes a footprint on the process performance of ores. In a comprehensive research work at the Sarcheshmeh porphyry copper mine, the geological features that affect the main process responses including the product grade and recovery and plant’s throughput are subjected to investigation. In the current report, the rock hardness variability in terms of semi-autogenous grinding power index (SPI) and its effects on the mill throughput and energy consumption are presented. Ninety samples are collected based on the geological features including lithology, hydrothermal alteration, and geological structures. The samples are mineralogically characterized using XRD, XRF, and electron and optical microscopy. The Starkey laboratory mill, commercialized by Minnovex, is used to perform the SPI comminution test. The SPI results show a wide range of hardness, varying from 12 to 473 minutes. The correlation between the SPI results and the geological features show that lithology is a key geological feature that defines the hardness variability. In addition, the hydrothermal alteration would be an effective parameter in the period that the plant is fed with a single lithology.Tue, 31 Mar 2020 19:30:00 +0100An Investigation on Effect of Shell Liner Type on Performance of Industrial SAG Mills Using DEM
http://jme.shahroodut.ac.ir/article_1677_195.html
The shell liner type, rotation speed, and ball filling percent are the key factors influencing the charge behavior inside the SAG mills, and consequently, their performance. In this work, the milling operation of industrial SAG mills is investigated using the Discrete Element Method (DEM). First, an industrial SAG mill with dimensions of 9.50 m × 4.42 m that has a Smooth-type liner is simulated. Then by changing the liner types, i.e. Wave, Rib, Ship-lap, Lorain, Osborn, and Step liners, six other independent simulations are performed. In order to investigate the impact mechanism and improve the mill performance, two new parameters called ‘head height’ and ‘impact zone length’ are introduced. Then the effects of the mill shell liner type on those parameters at two different mill speeds, i.e. 70% and 80% of its critical speed (CS), are evaluated. Also for validation of the simulation results, a laboratory-scale SAG mill with dimensions of 57.3 cm × 16.0 cm is simulated. The results obtained indicate that the Osborn liner, due to the angularity of its lifters and their proper number and thickness, performs best because it increases both parameters more than the other liners. Thus this liner is recommended as the best and optimal liner in this research work and is suggested for installation inside the industrial SAG mills. Also the Wave liner, due to its specific geometrical shape and its wavy lifters as well as their low number and inadequate thickness, provides the lowest charge ‘head height’. Therefore, it is not recommended to install this liner inside the industrial SAG mills. Meanwhile, comparison of the simulations related to the laboratory-scale SAG mill with the experimental results demonstrates a good agreement that validates the DEM simulations and the software used.Tue, 31 Mar 2020 19:30:00 +0100Investigating Alteration Zone Mapping Using EO-1 Hyperion Imagery and Airborne Geophysics Data
http://jme.shahroodut.ac.ir/article_1684_195.html
Hyperspectral remote sensing records reflectance or emittance data in a large sum of contiguous and narrow spectral bands, and thus has many information in detecting and mapping the mineral zones. On the other hand, the geological and geophysical data gives us some other fruitful information about the physical characteristics of soil and minerals that have been recorded from the surface. The Sarcheshmeh mining area located in the NW-trending Uromieh-Dokhtar magmatic belt within Central Iran is mainly of porphyry type, and is associated with extensive hydrothermal alterations. Due to the semi-arid type of climate with abundant rock exposure, this area is suitable for application of remote sensing techniques. In this work, we focus on generating the alteration maps around Cu porphyry copper deposits using the spectral angle mapper algorithm on Hyperion data by applying two filters named reduction to pole and analytical signal on a total magnetic intensity map and generating the Kd map from radiometry data. What is clear is the high importance of applying the adequate pre-processing on Hyperion data because of low signal-to-noise ratio. By comparing the known deposits in the region with the results obtained by applying the mentioned methods, it is revealed that not all the higher K radiometric values are entirely associated with the hydrothermal alteration zones, and in contrast, the potassic alteration map extracted from Hyperion imagery successfully corresponds to the alteration zones around the Sarcheshmeh mining area. Finally, the results particularly obtained from processing the Hyperion data are confirmed by indices of Cu porphyry deposits in the region.Tue, 31 Mar 2020 19:30:00 +0100On Analytic Solutions of Elastic Net Displacements around a Circular Tunnel
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Displacements around a tunnel, occurring as a result of excavation, consist of the elastic and plastic parts. In this paper, we discuss the elastic part of displacements as a result of excavation, called net displacement. In general, the previous analytical solutions presented for determining the displacements around a circular tunnel in an elastic medium do not give the net displacements directly. The well-known Kirsch solution is the most widely used method for determining the induced stresses and net displacements around a circular opening in a biaxially-loaded plate of homogeneous, isotropic, continuous, linearly elastic material. However, the complete solution for obtaining the net displacements has not been presented or highlighted in the available literature. Using the linear elasticity, this paper reviews and presents three different analytical methods for determining the net displacements directly as well as induced stresses around a circular tunnel. The three solution methods are the Lame' method, airy stress function method, and complex variable method. The tunnel is assumed to be situated in an elastic, continuum, and isotropic medium in the plane strain condition. The solutions are presented for both the hydrostatic and non-hydrostatic in situ stresses in the 2D biaxial loading condition along with an internal pressure. Loading and unloading in tunneling occurring as a result of excavation and stress differences between the induced and initial ones are considered to evaluate the net displacements directly. Finally, some examples are given to demonstrate the complete solution and show the difference between the net elastic displacements as a result of excavation and total elastic displacements that are not real.Tue, 31 Mar 2020 19:30:00 +0100Study of Damaged Zone around Circular Opening Using Acoustic Emission Technique
http://jme.shahroodut.ac.ir/article_1682_195.html
One of the methods used to investigate the damaged zone in rock structure is the acoustic emission method. This method is based on receiving the elastic waves that are produced by deformation and cracking of the rock mass around the underground excavation. In this research, a study is conducted on the rock samples by a numerical method to investigate the damaged zone caused by the excavation of circular space on it. For this purpose, 33 cube samples of three different material types including sandstone, concrete, and cement-plaster mortar are prepared. A circular hole is drilled in the center of each sample. The hole diameter is 20 or 25 mm. The samples are loaded uniaxially or biaxially with different stress rates. It is tried to study the acoustic events occurring in the samples during the test, and their locations are investigated. Then the experiments are evaluated by a numerical method using the FLAC3D software and some developed codes. The relation between the sample damaged zone where the acoustic events have occurred during the loading period and the numerical elements that reach a degree of tensile and shear yield is studied. The results obtained show that the amount of cumulative acoustic parameters in cement-plaster mortar specimens is more than the others. In fact, the finer grains, the more amounts of energy and counts will be produced. Also, the results show that with increase in the lateral pressure and loading rate, the amount of cumulative energy and counts decreases.Tue, 31 Mar 2020 19:30:00 +0100Detection of Zones Based on Ore and Gangue Using Fractal and Multivariate Analysis in Chah Gaz ...
http://jme.shahroodut.ac.ir/article_1691_195.html
Detection of mineralized zones based on ores and gangues is important for mine planning and excavation operation. The major goal of this research work was to determine the zones based on ores and gangues by a combination of fractal and factor analysis in the Chah Gaz iron ore (Central Iran). The Concentration-Volume (C-V) fractal method was carried out for Fe, P and S, which indicated that the main mineralized zones consisted of the Fe, S, and P values ≥ 57%, ≤ 0.4%, and ≤0.3%, respectively. Factor analysis categorized variables in two groups including factor 1 (F1) and factor 2 (F2) for ore and gangue, respectively. The C-V fractal modeling on the derived factors showed four zones for F1 and F2. Based on the correlation among the results of fractal modeling on the elements and factors, the first and second zones of F1 were proper for exploitation. Furthermore, the last and first zones of F1 and F2 could be assumed as the main waste for mining excavation.Tue, 31 Mar 2020 19:30:00 +0100A 3D Discrete Element Analysis of Failure Mechanism of Shallow Foundations in Rocks
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In this research work, a 3D numerical modeling technique is proposed based on the 3D particle flow code in order to investigate the failure mechanism of rock foundations. Two series of footings with different geometries and areas are considered in this work. The failure mechanism obtained is similar to that of the Terzaghi’s but there is a negligible difference in between. Lastly, one equation is presented to calculate the bearing capacity based on the results achieved from the numerical model and the Mohr-Coulomb theory. The sensitivity analyses are performed on the friction angle, cohesion, and footing width. The results obtained are compared with the corresponding results given by the equations given by Terzaghi and Meyerhof. This comparison demonstrates a good agreement between them. In the friction angle sensitive analysis, the amounts of the bearing capacity diagram are very close to Meyerhof’s, which overlap with each other.Tue, 31 Mar 2020 19:30:00 +0100An Optimum Selection of Simulated Geological Models by Multi-Point Geostatistics and ...
http://jme.shahroodut.ac.ir/article_1693_195.html
An accurate modeling of sophisticated geological units has a substantial impact on designing a mine extraction plan. Geostatistical simulation approaches, via defining a variogram model or incorporating a training image (TI), can tackle the construction of various geological units when a sparse pattern of drilling is available. The variogram-based techniques (derived from two-point geostatistics) usually suffer from reproducing complex and non-linear geological units as dyke. However, multipoint geostatistics (MPS) resolves this issue by incorporating a training image from a prior geological information. This work deals with the multi-step Single Normal Equation Simulation (SNESIM) algorithm of dyke structures in the Sungun Porphyry-Cu system, NW Iran. In order to perform a multi-step SNESIM algorithm, the multi-criteria decision-making and MPS approaches are used in a combined form. To this end, two TIs are considered, one for simulating dyke structures in the shallow depth, and two for simulating dyke structures in a deeper depth. In the first step, a TI is produced using geological map, which has been mined out during the previous exploration operations. After producing TI, the 35 realizations are simulated for the shallow depth of deposit in the area under study. To select the best realization (as a TI for the next step) of the simulation results, several statistical criteria are used and the results obtained are compared. To this end, a hybrid multi-criteria decision-making is designed on the basis of a group of statistical criteria. In the next step, the dyke structures in the deeper depth are also simulated by the new TI.Tue, 31 Mar 2020 19:30:00 +0100A New Method for Forecasting Uniaxial Compressive Strength of Weak Rocks
http://jme.shahroodut.ac.ir/article_1701_195.html
The uniaxial compressive strength of weak rocks (UCSWR) is among the essential parameters involved for the design of underground excavations, surface and underground mines, foundations in/on rock masses, and oil wells as an input factor of some analytical and empirical methods such as RMR and RMI. The direct standard approaches are difficult, expensive, and time-consuming, especially with highly fractured, highly porous, weak, and homogeneous rocks. Numerous endeavors have been made to develop indirect approaches of predicting UCSWR. In this research work, a new intelligence method, namely relevance vector regression (RVR), improved by the cuckoo search (CS) and harmony search (HS) algorithms is introduced to forecast UCSWR. The HS and CS algorithms are combined with RVR to determine the optimal values for the RVR controlling factors. The optimized models (RVR-HS and RVR-CS) are employed to the available data given in the open-source literature. In these models, the bulk density, Brazilian tensile strength test, point load index test, and ultrasonic test are used as the inputs, while UCSWR is the output parameter. The performances of the suggested predictive models are tested according to two performance indices, i.e. mean square error and determination coefficient. The results obtained show that RVR optimized by the HS model can be successfully utilized for estimation of UCSWR with R2 = 0.9903 and MSE = 0.0031203.Tue, 31 Mar 2020 19:30:00 +0100Application of Phytoremediation to Reduce Environmental Pollution of Copper Smelting and ...
http://jme.shahroodut.ac.ir/article_1715_195.html
Copper smelting and refinery factories are the final stages of a pyrometallurgical processing chain, and they cause many environmental challenges around the world. One of the most common environmental problems of these factories is toxic emissions. These toxic gases have harmful effects on the vegetation, animal species, soils, and water resources around the factories. Phytoremediation can play an important role in the reduction of the adverse effects of environmental pollutions arising from copper smelting and refinery factories. In this paper, we first discuss different types of pollutions caused by copper metallurgical factories, and present the main research approaches and studies conducted on these factories. In the second part, we provide a summary and comparison of different remediation technologies used to reduce the environmental pollutions of these factories. Besides, the advantages and disadvantages of each method is also investigated. In the third part, we review the different aspects of the phytoremediation including the effective mechanisms, different types of plants, application environments, and the effective factors. The next part includes the selection of suitable plants for the phytoremediation process applied for copper metallurgical factories and investigation of the native and cultivated hyperaccumulator plants. In addition, different efficiency indices are introduced for evaluating the phytoremediation efficiency and selecting an appropriate hyperaccumulator plant. At the final stage, some appropriate plant species for various types of phytoremediation are introduced. The effects of different environmental stresses and the possibilities of integrating phytoremediation with other remediation technologies as well as the advantages and disadvantages of phytoremediation are eventually investigated.Tue, 31 Mar 2020 19:30:00 +0100TBM Tunneling Construction Time with Respect to Learning Phase Period and Normal Phase Period
http://jme.shahroodut.ac.ir/article_1717_195.html
In every tunnel boring machine (TBM) tunneling project, there is an initial low production phase so-called the Learning Phase Period (LPP), in which low utilization is experienced and the operational parameters are adjusted to match the working conditions. LPP can be crucial in scheduling and evaluating the final project time and cost, especially for short tunnels for which it may constitute a major percentage of the total project completion time. The contractors are required to have a better understanding of the initial phase of a project to provide better estimates in the bidding documents. While evaluating and shortening of this phase of low production is important for increasing the productivity and daily advance rate of the machine, there has been limited a direct study and assessment of this period. In this work, we discuss the parameters impacting LPP, and introduce a new methodology for its evaluation. In this regard, an algorithm is introduced for estimation of the approximate extent of LPP based on some TBM tunneling case histories. On the basis of many statistical analyses conducted on the actual data and application of two different shapes of linear and polynomial for the description of LPP, a linear function is proposed for estimation of the learning phase parameters. The major parameters of this function are the learning conditions’ rating and the proportion of LPP to tunnel diameter (X1/D). Analysis of the correlation between these two parameters show a very good coefficient of determination (R2 = 92%). This function can be used for the evaluation of TBM advance rates in LPP and for adjusting the TBM utilization factor in the initial stages of a TBM tunneling project. The learning phase can affect the overall utilization rate and completion time of the tunnels, especially when their lengths are around a couple of kilometers. A true understanding of the LPP characteristics can help the contractors to come up with a more accurate bidding time and cost evaluation, and may also benefit the clients to arrange a better schedule for the final project delivery to the public.Tue, 31 Mar 2020 19:30:00 +0100Application of Power-Law Frequency Fractal Model for Recognition of Vertical Cu Distribution in ...
http://jme.shahroodut.ac.ir/article_1723_195.html
Identification of the vertical and horizontal distributions for elemental grades is of an important sign in different mineral exploration stages. The main aim of this work is to determine the vertical distribution directional properties of Cu values in the Milloieh Cu porphyry deposit, Kerman (SE Iran) using the power-law frequency fractal model. This work is carried out based on four mineralized boreholes. The Cu grade vertical distribution in mineralized boreholes indicates a positively skewed distribution in the former and multi-modal distribution in the latter types. The power-law frequency analysis in nature represents that the Cu values in four mineralized boreholes are bifractal. The two sections of these graphs outline a break point of about 0.5-1% for Cu values and fractal dimension range of 1.70-4.97 in the mineralized boreholes.Tue, 31 Mar 2020 19:30:00 +0100A Modified Schimazek’s F-abrasiveness Factor for Evaluating Abrasiveness of Andesite Rocks in ...
http://jme.shahroodut.ac.ir/article_1726_195.html
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.Tue, 31 Mar 2020 19:30:00 +0100Development of An Integrated Mathematical Model to Optimize Waste Rock dumping Satisfying ...
http://jme.shahroodut.ac.ir/article_1732_195.html
Waste rock dumping is very important in the production planning of open-pit mines. This subject is more crucial when there is a potential of acid-forming (PAF) by waste rocks. In such a type of mines, to protect the environment, the PAF materials should be encapsulated by non-harmful rocks. Therefore, block sequencing of the mined materials should be in such a way that both the environmental and economic considerations are considered. If non-acid forming (NAF) rocks are not mined in a proper time, then a stockpile is required for the NAF materials, which later on would be re-handled for encapsulation of PAF rocks. In the available models, the focus is on either block sequencing or waste dumping strategy. In this work, an attempt has been made to develop an integrated mathematical model for simultaneous optimization of block sequencing and waste rock dumping. The developed model not only maximizes the net present value (NPV) but also decreases the destructive environmental effects of inappropriate waste dumping. The proposed model, which is solved by a CPLEX engine, is applied to two different iron deposits. Also the performance of the proposed model is cross-checked by applying the available (traditional) models in a two-step manner. According to the results obtained, it can be considered that utilizing the developed model, because of extensive re-handling cost reduction, the NPV improvement is significant, especially when the overall stripping ratio is higher (deposit case A).Tue, 31 Mar 2020 19:30:00 +0100Method of Grading Subway Stations Based on Evacuation Capability: A Quantitative Method
http://jme.shahroodut.ac.ir/article_1741_195.html
Stations are the main components of the subway systems. Despite the progress in the construction and maintenance, stations have always been exposed to the natural and man-made disasters. In such incidents, the station’s evacuation capability has a direct relation with a passenger's life. Various factors affect the station's evacuation capability. Investigation of these factors and evaluation of the station’s evacuation capability have important roles in protecting a passenger's life. For this purpose, the catastrophic events that lead to the evacuation of a station and the factors affecting the evacuation of the station are identified. Due to the difference in the catastrophic event probabilities at each station, the risk of catastrophic events is evaluated. Then the station score is calculated according to the value and weight of the evacuation factors and the wighted influence of the catastrophic events. Accordingly, the proposed model is implemented in the Tehran subway. Based on the results obtained, uncrowded stations, even though served by a small number of passengers, may also have a low evacuation capacity and lead to casualties in an emergency situation. This is due to the lack of emergency management and safety facilities. Also by assessing the risk of catastrophic events at stations and equipping stations on its basis, the degree of safety and evacuation capability can be improved more effectively. The sensitivity analysis of the evacuation factors show that the most effective way to increase the station’s evacuation capability is to improve its status in management factors. Using the proposed model to evaluate the station's evacuation capability is an appropriate method for identifying the stations that have a poor evacuation capability.Tue, 31 Mar 2020 19:30:00 +0100A Hybrid Fuzzy MCDM Approach to Determine an Optimal Block Size in Open-Pit Mine Modeling: a ...
http://jme.shahroodut.ac.ir/article_1747_195.html
The computer-based 3D modeling of ore bodies is one of the most important steps in the resource estimation, grade determination, and production scheduling of open-pit mines. In the modeling phase, the volume of the orebody model is required to be filled by the blocks and sub-blocks. The determination of Block Size (BS) is important due to the dependence of the geostatistical issues and calculations related to mining capabilities on it. There are some factors effective in the determination of an optimal BS including the metal content, estimation error, recovery percentage, mining ability, safety, and dilution. In this work, an optimal BS is determined using a two-stage approach. In the proposed approach, the Fuzzy Delphi Analytic Hierarchy Process (FDAHP) and Fuzzy Multi-Objective Optimization by Ratio Analysis (FMOORA) methods are used. In the first phase, the weight of each criterion is calculated based on the opinions of the experts using the FDAHP method. In the second phase, the FMOORA method is applied in order to determine a suitable BS for the design and operation of mining considering the extracted weights in the previous phase. The block model of the Sungun copper mine is studied as a case study to evaluate the capability of the proposed approach. The results of implementation of this approach are desirable because of converting the opinions of the experts to fuzzy values, weighing the experts according to the experience and technical knowledge, weighting the criteria by FDAHP, and choosing the optimal option with FMOORA. Furthermore, the 12.5×12.5×12.5 m3 block (A5) is chosen as an appropriate BS, which is compatible with the real conditions of the studied mine.Tue, 31 Mar 2020 19:30:00 +01003D Characterization of Uniaxial Compressive Strength of Transversely-Isotropic Intact Rocks
http://jme.shahroodut.ac.ir/article_1749_195.html
The uniaxial compressive strength (UCS) of intact rocks is one of the key parameters in the course of site characterizations. The isotropy/anisotropy condition of the UCS of intact rocks is dependent on the internal structure of the rocks. The rocks with a random grain structure exhibit an isotropic behavior. However, the rocks with a linear/planar grain structure generally behave transversely-isotropic. In the latter case, the UCS of intact rocks must be determined by a set of laboratory tests on the oriented rock samples. There are some empirical relations available to describe the strength of these rocks. Though characterization of transversely-isotropic rocks is practically a 3D problem, but these relations provide only a 2D description. In this paper, a method is proposed to provide a 3D description of UCS of transversely-isotropic rocks. By means of this formulation, one can determine UCS along with any arbitrary spatial direction. Also, a representative illustration of UCS is proposed in the form of contour-plots on a lower hemisphere Stereonet. The method is applied to an actual case study from the Kanigoizhan dam site located in the Kurdistan Province (Iran). Application of the proposed method to the phyllite rocks of this site show that the direction perpendicular to the dam axis exhibits the most anisotropic behavior. Hence, it is essential to take the strength anisotropy into account during the relevant analysis. The results obtained, together with the statistical variation of UCS, provide a practical approach to select the proper values of UCS according to the scope of the analysis.Tue, 31 Mar 2020 19:30:00 +0100Investigation of the effect of the number of lifters on performance of pilot-scale SAG mills ...
http://jme.shahroodut.ac.ir/article_1688_0.html
The number of lifters of mill shell liners, mill rotation speed, and filling percentage of grinding media are three of the most important parameters influencing the charge behavior and the trajectory of ball motion inside the SAG mills, and consequently, their performance. In this paper, the milling operation of pilot-scale SAG mills using the discrete element method (DEM) is investigated. First, a pilot-scale SAG mill with dimensions of 3.0 m × 1.5 m with no lifter is simulated. Then by adding, respectively, one, two, four, eight, sixteen, and thirty-two rectangle lifter(s), six other independent simulations are performed. The effects of the number of lifters on the two new parameters introduced by the authors, i.e. ‘head height’ and ‘impact zone length’ as well as on creation of cascading, cataracting, and centrifuging motions for balls at two different mill speeds, i.e. 70% and 80% of its critical speed (NC), are evaluated. Also in order to validate the simulation results, a laboratory-scale SAG mill is simulated. The results obtained indicate that the optimum number of lifters for pilot-scale SAG mills is between 16 and 32 lifters with medium thickness. Liners with the number of lifters in this range require less mill speed to create cataract motions. However, liners with the number of lifters less than this range require a higher mill speed. Also liners with the number of lifters beyond this range require less mill speed, and can cause centrifugal motions in the balls. Comparison of the simulations related to the laboratory-scale SAG mill with experimental results demonstrates a good agreement, which validates the DEM simulations and the software used.Tue, 25 Feb 2020 20:30:00 +0100Application of Sequential Gaussian Conditional Simulation into Underground Mine Design Under ...
http://jme.shahroodut.ac.ir/article_1540_0.html
In mining projects, all uncertainties associated with a project must be considered to determine the feasibility study. Grade uncertainty is one of the major components of technical uncertainty that affects the variability of the project. Geostatistical simulation, as a reliable approach, is the most widely used method to quantify risk analysis to overcome the drawbacks of the estimation methods used for an entire ore body. In this work, all the algorithms developed by numerous researchers for optimization of the underground stope layout are reviewed. After that, a computer program called stope layout optimizer 3D is developed based on a previously proposed heuristic algorithm in order to incorporate the influence of grade variability in the final stope layout. Utilizing the sequential gaussian conditional simulation, 50 simulations and a kriging model are constructed for an underground copper vein deposit situated in the southwest of Iran, and the final stope layout is carried out separately. It can be observed that geostatistical simulation can effectively cope with the weakness of the kriging model. The final results obtained show that the frequency of economic value for all realizations varies between 6.7 M$ and 30.7 M$. This range of variation helps designers to make a better and lower risk decision under different conditions.Tue, 03 Sep 2019 19:30:00 +0100Dilution risk ranking in underground metal mines using Multi-Attributive Approximation area ...
http://jme.shahroodut.ac.ir/article_1650_0.html
The contamination of ores with wastes or materials of lower than the cut-off grade is referred to as dilution. Dilution is an undesirable phenomenon that, on one hand, reduces the product grade and, consequently, reduces the sales prices and, on the other hand, adds an extra cost to waste production. Therefore, studying and evaluating the dilution risk is important in mining, and especially in underground mining. In this work, using a powerful decision-making method, i.e. Multi-Attributive Approximation Area Comparison (MABAC), the dilution risk and ranking it in underground mines are assessed. For this purpose, the most important parameters affecting the dilution in 10 mines of the Venarch manganese mines are first identified and then weighed using the Fuzzy Delphi Analytical Hierarchy Analysis (FDAHP) method. Then using the MABAC method, the dilution risk score for each mine is estimated, and subsequently, various mines are ranked as the dilution risk. Then with the implementation of the Cavity Monitoring System (CMS) and measurement of the actual dilution values, the mines are ranked in dilution. The correct matching of the results of these two rankings indicates that the MABAC method is highly effective in the ranking of the risk. At the end, the risk ranking of the mines is done using the TOPSIS method, and the lack of full compliance with the results of this method with the actual values indicates that the MABAC method is preferable to the TOPSIS method.Tue, 24 Dec 2019 20:30:00 +0100Risk assessment of flyrock in surface mines using FFTA-MCDMs combination
http://jme.shahroodut.ac.ir/article_1666_0.html
The drilling and blasting method is the first choice for rock breakage in surface or underground mines due to its high flexibility against variations and low investment costs. However, any method has its own advantages and disadvantages. The flyrock phenomenon is one of the drilling and blasting disadvantages that the mining engineers have always been faced with in the surface mine blasting operations. Flyrock may lead to fatality and destroy mine equipment and structures, and so its risk assessment is very essential. For a flyrock risk assessment, the causing events that lead to flyrock along with their probabilities and severities should be identified. For this aim, a combination of the fuzzy fault tree analysis and multi-criteria decision-making methods are used. Based on the results obtained, the relevant causing events of flyrock in surface mines can be categorized into three major groups: design error, human error, and natural error. Finally, using the obtained probabilities and severities for these three groups, the risk matrix is constructed. Based on the risk matrix, the risk numbers of flyrock occurrence due to the design errors, human errors, and natural influence are 12, 6, and 2, respectively. Hence, in order to minimize the flyrock risk, it is very vital for the engineers to select appropriate values for the design events of blasting pattern such as burden, spacing, delays, and hole diameter.Wed, 22 Jan 2020 20:30:00 +0100On the applicability of some indirect tests for estimation of tensile strength of anisotropic rocks
http://jme.shahroodut.ac.ir/article_1696_0.html
The tensile strength of rocks plays a noteworthy role in their failure mechanism, and its determination can be beneficial in optimizing the design of the rock structures. Schistose rocks due to their inherent anisotropy in different foliation directions show a diverse strength at each direction. The purpose of this work was to compare and assess the tensile strength of phyllite, which was obtained in direct and indirect tensile tests in different foliation directions. To this end, several phyllite specimens with different foliation angles (0º, 30º, 45º, 60º, and 90º) related to the loading axis (β) were prepared. Finally, the direct tensile test, diametrical and axial point load tests, Brazilian test, and Schmidt hammer test were conducted on 188 samples. The results of the experimental tests revealed that the maximum and minimum tensile strengths in direct tensile testing tension were directly related to the angles of 0º and 90º. Also it was observed that the Brazilian tensile strength overestimated the tensile strength. Furthermore, an exponential correlation was introduced between the direct tensile strength and the Brazilian tensile strength.Fri, 06 Mar 2020 20:30:00 +0100A comprehensive study of several meta-heuristic algorithms for the open-pit mine production ...
http://jme.shahroodut.ac.ir/article_1718_0.html
It is significant to discover a global optimization in the problems dealing with large dimensional scales to increase the quality of decision-making in the mining operation. It has been broadly confirmed that the long-term production scheduling (LTPS) problem performs a main role in mining projects to develop the performance regarding the obtainability of constraints, while maximizing the whole profits of the project in a specific period. There is a requirement for improving the scheduling methodologies to get a good solution since the production scheduling problems are non-deterministic polynomial-time hard. The current paper introduces the hybrid models so as to solve the LTPS problem under the condition of grade uncertainty with the contribution of Lagrangian relaxation (LR), particle swarm optimization (PSO), firefly algorithm (FA), and bat algorithm (BA). In fact, the LTPS problem is solved under the condition of grade uncertainty. It is proposed to use the LR technique on the LTPS problem and develop its performance, speeding up the convergence. Furthermore, PSO, FA, and BA are projected to bring up-to-date the Lagrangian multipliers. The consequences of the case study specifies that the LR method is more influential than the traditional linearization method to clarify the large-scale problem and make an acceptable solution. The results obtained point out that a better presentation is gained by LR–FA in comparison with LR-PSO, LR-BA, LR-Genetic Algorithm (GA), and traditional methods in terms of the summation net present value. Moreover, the CPU time by the LR-FA method is approximately 16.2% upper than the other methods.Tue, 24 Mar 2020 19:30:00 +0100Effect of segmental joint on internal force in tunnel lining under seismic loading by numerical ...
http://jme.shahroodut.ac.ir/article_1751_0.html
Although segmental tunnel linings are often used for seismic areas, the influence of segment joints on the segmental lining behavior under seismic loading has not been thoroughly considered in the literature. This paper presents the results of a numerical study investigating the effect of the rotational, axial and radial joint stiffness of the longitudinal joints on structural forces in segmental tunnel lining under seismic loading. A 3D finite element method was adapted to establish elaborate numerical models of segments. The validity of the numerical model was tested by comparing results of this paper to the well-known analytical methods presented by Wang and Penzien. Results demonstrated that by increasing rotational stiffness of the segmental joint, bending moment increases. When rotational stiffness ratio is less than 0.5, the positive and negative bending moment variations are more. Numerical modeling results showed the variations of the bending moment and difference between positive and negative bending moment values increased by increasing the acceleration of seismic loading. Moreover, it is significant for values. By increasing rotational stiffness ratio of the segmental joint, the axial force ratio decreases. By increasing the axial and shear stiffness ratio of segmental joint, the variations of bending moment and axial force in segmental lining was not significant and could be ignorable to design segmental lining.Sun, 10 May 2020 19:30:00 +0100Comparison of copper dissolution in chalcopyrite concentrate bioleaching with Acidianus ...
http://jme.shahroodut.ac.ir/article_1756_0.html
Although bioleaching of chalcopyrite by thermophilic microorganisms enhances the rate of copper recovery, high temperature accelerates iron precipitation as jarosite, which can bring many operational problems in industrial processes. In this research, the bioleaching of chalcopyrite concentrate by the thermophilic Acidianus brierleyi was studied, and microbial growth, copper dissolution, iron oxidation, and jarosite precipitation were monitored in different initial pH (pHi). Bacterial growth was greatly affected by pHi. While bacterial growth delayed for 11 days with pHi of 0.8, this delay reduced to nearly one day for pHi of 1.2. Two stages of copper recovery were observed during all tests. High pHi caused fast bacterial growth in the first stage and severe jarosite precipitation in later days, causing a sharp decline in bacterial population and copper leaching rate. The copper recoveries after 11 days, were 25, 78, 84, 70, 56 and 39% for pHi of 0.8, 1.0, 1.2, 1.3, 1.5 and 1.7, respectively. Sulfur and jarosite were the main residues of bioleaching tests. It was revealed that the drastic effect of jarosite precipitation on microbial growth and copper recovery was mainly caused by ferric iron depletion from solution, rather than passivation of chalcopyrite surface. Slow precipitation of crystalline jarosite did not cause a passive chalcopyrite surface. The mechanisms of chalcopyrite bioleaching were discussed.Tue, 19 May 2020 19:30:00 +0100A New Mathematical Model for Production Scheduling in Sublevel Caving Mining Method
http://jme.shahroodut.ac.ir/article_1773_0.html
Production scheduling in underground mines is still a manual process and achieving the truly optimal result through manual scheduling is impossible due to the complexity of the scheduling problems. Among underground mining methods, sublevel caving is a common mining method for hard rock mining with a high production rate. There are limited studies about long-term production scheduling in the sublevel caving method. In this paper, for sublevel caving production scheduling optimization, a new mathematical model with the objective of net present value (NPV) maximization is developed. General technical and operational constraints of sublevel caving method such as opening and developments, production capacity, sublevel mining geometry, and ore access are considered in this model. Prior to applying the scheduling model, the block model is processed to remove the unnecessary blocks. For this purpose, the floating stope algorithm is applied to determine the ultimate mine boundary and reduce the number of blocks that consequently reduces the running time of the model. The model was applied on a bauxite mine block model and the maximum NPV is determined, then the mine development network is designed based on the optimal schedule.Fri, 22 May 2020 19:30:00 +0100Comparative Analysis of Coal Miner’s Fatalities by Fuzzy Logic
http://jme.shahroodut.ac.ir/article_1774_0.html
This study has employed fuzzy logic technique for the first time to achieve and present a proper analysis of the actual intensity of increasing coal miners’ fatality rates in Pakistan from 2010 to 2018, comparing with China and India, with an objective to minimize the impact of incidents on miner’s fatalities. The average and year wise fatality rates per million tons of Pakistan compared with China and India were used for fuzzy logic to calculate the actual degree of flexibility for surging fatalities in this paper. The findings have shown that both the average and year wise fatality rates in 2011, 2015 and 2018 as 2.44, 1.74 and 1.6 respectively. In fuzzy logic the variables whose membership function (µ) values are ≥1 represent absolute truth. The membership function values for years 2011, 2015, and 2018 are alarming high for the fatalities of coal miners. In the same manner, except for 2014 and 2010, where 0 represents absolute falseness and results in remaining years indicate high fatality rates with a flexibility (or small extent) of its corresponding membership function (µ) values such as 0.623, 0.739, 0.219, 0.173 and 0.115, and 0.714, 0.24, 0.01, 0.324 and 0.317 using average and year wise analysis, respectively compared with China. Likewise, the fuzzy logic membership function (µ) values compared with India in the remaining years are, with a small extent of 0.704, 0.795, 0.386, 0.159, 0.352 and 0.306, and 0.675, 0.795, 0.386, 0.186, 0.321 and 0.322 correspondingly. The study suggest the recommendations to reduce fatalities.Sat, 23 May 2020 19:30:00 +0100Dissolution of nickel and cobalt from iron-rich laterite ore using different organic acids
http://jme.shahroodut.ac.ir/article_1777_0.html
Due to the decreasing production of nickel and cobalt from sulfide sources, Ni and Co extraction from oxide ores (laterites) have become more prevalent. In this research work, the effect of calcination prior to leaching, acid concentration, percent solids, pH and stirring speed on nickel and cobalt recoveries from iron-rich laterite ore sample, using organic acids were investigated. Then the response surface methodology was implemented to optimize the various parameters. By Design of experiments, the compound optimal concentration of the three different organic acids (gluconic acid: lactic acid: citric acid with a ratio of 1: 2: 3) were 3.18 M, S/L =0.1, pH = 0.5, the stirring speed =386 rpm. With the aid of kinetic studies, temperature 75 °C and test time of 120 minutes, the highest nickel and cobalt recoveries were 25.5% and 37.6%, respectively. In optimal condition, the contribution of the percent solids on the nickel recovery was the most and negative, after which the contribution of pH was negative, and finally, the acid concentration positively affected. In optimal condition, acid concentration, pH, and solids content were important in cobalt recovery, respectively. The SEM results showed that the surface of feed and residue particles in optimal condition were not significantly different, and laboratory data was fitted to a shrinking core model. The results indicated that the reaction rate was controlled by the diffusion reaction at the particle surface, and the activation energy of 11.09 kJ/mol for nickel and 28.04 kJ/mol for cobalt were consistent with this conclusion.Tue, 26 May 2020 19:30:00 +0100Blast Design for Improved Productivity using a Modified Available Energy method
http://jme.shahroodut.ac.ir/article_1778_0.html
In this study, a new drilling and blasting design methodology is introduced and applied at a case study mine to improve productivity. For the case study copper mine, a blast diameter of 203mm has been proposed to be used in the ore zone to meet the new required production rate of 90mtpa from 75mtpa. Currently, Konya and Walter’s model is used to generating drilling and blasting design at the blasthole diameter of 172mm. The new drilling and blast design approach is advantageous in the sense that it generates a lower specific drilling value and predicted average fragment size than the current method being used. In this regard, a Modified Available Energy blast design method that incorporates the blastability index of ore zone in the calculation of the input powder factor has been introduced. The results of the blast design simulations at 203mm blasthole diameter showed that the Modified available energy model generates drilling and blasting design with a specific drilling value that is 15.3% less than that generated by Ash’s and Konya and Walter’s model. Further, the Modified Available Energy model generated a blast design with a predicted average fragment size that is 3.4 % smaller than that generated by Ash’s model, and 6.7% smaller than that generated by Konya and Walter’s Model.Tue, 26 May 2020 19:30:00 +0100A Correlation for Estimating LCPC Abrasivity Coefficient Using Rock Properties
http://jme.shahroodut.ac.ir/article_1782_0.html
Abrasivity, as one of the most important parameters affecting rock drillability, significantly influences drilling rate in mines. Therefore, rock abrasivity should be carefully evaluated prior to selecting and employing drilling machines. Since tests for rock abrasivity assessment require sophisticated laboratory equipment, empirical models can be used to predict it. Several indices based on five known methods have been introduced for assessing rock abrasivity including rock abrasivity index (RAI), Cerchar abrasivity index (CAI), Schimazek’s abrasivity factor (F-abrasivity), bit wear index (BWI), and LCPC abrasivity coefficient (LAC). In this study, 12 rock types with different origins were investigated using uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), longitudinal wave velocity and LCPC tests together with microscopic observations were performed to obtain a correlation for estimating LCPC abrasivity coefficient by employing conventional rock mechanics experiments. Using equivalent quartz content, velocity of longitudinal waves and rock brittleness index, a linear correlation was obtained with the help of SPSS software to estimate the LCPC abrasivity coefficient with the coefficient of determination (R2) of 93.3%.Wed, 03 Jun 2020 19:30:00 +0100A 3D finite-difference analysis of the interaction between a newly driven large tunnel with the ...
http://jme.shahroodut.ac.ir/article_1783_0.html
Evaluation of interaction between new and existing underground structures is one of the important problems in urban tunneling. In this study, using the FLAC3D, a numerical model of single and twin-tube tunnels in urban areas has been developed where the horizontal distance between the single and twin-tube tunnels was varied. The aim was to analyze the effects of horizontal distances, considering various criteria such as deformation of linings, forces and moments exerted on the twin-tube tunnels and their factors of safety, subsidence that occurred on the surface and nearby buildings, the stability of the single-tube tunnel and stability of the pillar lying between the single and twin-tube tunnels. Considering the above-mentioned criteria, the results indicate that the interaction between the single and twin-tube tunnels is virtually negligible in the distance more than three times the single-tube tunnel diameter. Also, the stability of the pillar lying between the tunnels makes the distance to be chosen at least 1.5 times their diameter.Wed, 03 Jun 2020 19:30:00 +0100