فهرست مطالب

Mining & Geo-Engineering - Volume:51 Issue: 2, Summer and Autumn 2017

International Journal of Mining & Geo-Engineering
Volume:51 Issue: 2, Summer and Autumn 2017

  • تاریخ انتشار: 1396/10/08
  • تعداد عناوین: 13
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  • Elyyeh Moafi Madani, Hossein Hasani, Mehdi Sadighi Hashtjin, Marzieh Hosseini-Nasab* Pages 105-112
    This study aims to assess landslide susceptibility in Pahne Kola watershed located in the south of Sari, based on bivariate logistic regression. For this purpose, the distribution map of the area’s landslides was firstly prepared in ArcGIS software. Eight effective factors on landslide event including elevation, slope, slope aspect, rainfall, land use, distance from the road, soil and geology were considered as independent variables. PGA is same for all the area because the study area is small. The independent variables including eight effective factors were including 61 sliding points as dependent variable, and number 1 was devoted to the presence and zero was devoted to absence of landslide. After quantitative analysis, the related data was transferred to SPSS software and after interpreting the coefficients, just the distance from the road was recognized as a significant variable influencing the final equation and the other independent variables were omitted from the final equation because of the lack of statistical correlation. After transferring the final probability equation to ArcGIS software, the landslide hazard map was prepared. Statistical model accuracy was evaluated and approved by omnibus test, model summary table, classification graph and table. Statistical evaluation of the model showed that the overall accuracy of prepared map was 85.2%.
    Keywords: ArcGIS software, PGA, Pahne Kola, omnibus test
  • Hassan Bakhshandeh Amnieh *, Majid Masoudi Pages 113-118
    Cement grouting is an operation often carried out to consolidate and seal the rock mass in dam sites and tunnels. The quality and efficiency of a grouting operation depends on various factors such as water take, grout properties and grouting pressure. One of the parameters which have the highest effect is pressure since the application of excessive pressure causes the hydraulic fracture phenomenon to occur in the rock mass and too little pressure leads to incomplete grouting and failure to seal the site in a perfect manner. Mathematical modeling is used for the first time in this study to predict and determine the optimum pressure. Thus, the joints that exist in the rock mass are simulated using cylindrical shell model. The joint surroundings are also modeled through Pasternak environment. To obtain equations governing the joints and the surroundings, energy method is used accompanied by Hamilton principle. In the end, an analytical solution method is used to obtain the maximum grouting pressure. In order to validate the modeling, the grouting pressure values obtained by the model were used in the sites of Seymareh and Aghbolagh dams and the relative error rates were measured considering the differences between calculated and actual pressures. Modeling in the examined sections of Seymareh dam showed 29.61, 5.57, 21.98, 32.50 and 9.09 percent error rates and in the sections of Aghbolagh dam it rendered the values of 4.32, 5.40 and 2.96 percent. The results indicate that this modeling can be used to estimate the amount of pressure for hydraulic fracture in grouting, to predict it and to prevent it.
    Keywords: hydraulic fracture, mathematical modeling, cylindrical shell model, Seymareh, Aghbolagh dams
  • Ataallah Bahrami *, Mohammad Raouf Hosseini, Mohammadhosein Rahimi Pages 119-123
    In the present research work, a low-ash coal, from Ghouzlou deposit in Iran, with an average ash content of 12% was subjected to some beneficiation experiments such as heavy media separation and flotation. Sieve analysis showed that 62.3% of the coal sample with the size of mm had around 7.3% ash contents. Also, heavy media tests carried out on five size fractions revealed that by setting the separation density at 1.4 g/cm3 for the coarse fraction ( mm), a 5% ash product with more than 70% coal recovery was obtainable. Samples with lower ash content (5%) based on the Mayer curves to produce a 5% coal product. Moreover, flotation tests on -1 mm fraction could reduce the ash content from more 13.2% to 10.4%.
    Keywords: Coal, Heavy media separation, Sieve analysis, Flotation
  • Reza Mikaeil, Saleh Ghadernejad *, Mohammad Ataei, Mahmoud Esmailvandi, Abdolsalam Daneshvar Pages 125-132
    This study aimed to develop new statistical models for evaluating the specific ampere draw (SI) based on rock brittleness index in rock sawing process. A variety of rocks, including carbonate and granite, were cut by a fully instrumented laboratory-sawing rig with two different types of circular diamond saws. Laboratory tests were performed at different depths of cut and feed rates. Multiple curvilinear regression analysis was utilized in order to estimate the SI from rock brittleness index and operational parameters. Validation of the developed models was checked by t and F tests. Results showed that among the different brittleness indexes, B3 has the best accuracy for both granite and carbonate rocks. Finally, it was concluded that the specific ampere draw can be reliably predicted using the proposed models for both hard and soft rocks.
    Keywords: Brittleness Indexes, Sawing Process, Specific Ampere Draw, Statistical Analysis
  • Mohammad Hajiazizi *, Mina Hashemi Pages 133-138
    Having knowledge of stability of an underground space depends on stresses and strains around it. Creating underground tunnels leads to significant changes in the rock mass stress. Therefore, to achieve the necessary stability, stresses and deformations around the tunnel must be examined carefully. Usually, stress-strain behavior analysis is conducted in two-dimensional mode. This paper was conducted to compare two-dimensional and three-dimensional analysis of deformation around the tunnel proposed as new work in relationship between the two-dimensional and three-dimensional deformation. Then, its impact on the value of Q-system in seismic mode is studied. Two-dimensional analyses are usually conservative. Therefore, the proposal relationship between two-dimensional and three-dimensional mode will lead to reduced costs and save in support materials. The results of different analyses in the intact and sparsely jointed rock masses show that displacement around the tunnel is greater in two-dimensional analysis compared with three-dimensional analysis. However, in the heavily jointed rock masses, displacement around the tunnel is lower in two-dimensional analysis than three-dimensional one. As three-dimensional analyses are closer to reality, results of equations proposed in this paper can be used to calculate three-dimensional displacement. Different analyses for intact or sparsely jointed rock masses carried out in 2D and 3D states. According to conclusions made, the new equation proposed between 2D (U_2D) and 3D (U_3D) displacement. Data obtained by local measurements (3D) and the results of the 2D analyses for heavily jointed rock masses were compared. Then relationship between 2D and 3D displacements in the heavily jointed rock masses proposed. The results of this research have been applied for tunnel of Gavoshan Dam in West of Iran. There is good consistency between equations proposed in this paper and three-dimensional analyses.
    Keywords: 3D displacement, Q-Value, 2D displacement, Heavily jointed rock mass
  • Mohsen Nazari Ostad, Omid Asghari *, Ali Rafiee, Mehran Azizzadeh, Farhad Khoshbakht Pages 139-146
    Fracture orientation is a prominent factor in determining the reservoir fluid flow direction in a formation because fractures are the major paths through which fluid flow occurs. Hence, a true modeling of orientation leads to a reliable prediction of fluid flow. Traditionally, various distributions are used for orientation modeling in fracture networks. Although they offer a fairly suitable estimation of fracture orientation, they would not consider any spatial structure for simulated fracture orientations, and would not able to properly reproduce the histograms, and the stereogram of dip and azimuth. To respect this geostatistical and statistical parameters, in this paper a new approach has been presented in which the observed fractures on the image log are firstly clustered, and the major facture families are categorically simulated over the area of study. Afterwards, azimuths are simulated using the probability field obtained from categorical simulation, and dips are conditionally simulated to azimuths. The method is illustrated through a case and the results show that the histograms and stereograms are completely reproduced. In addition, the connectivity of modeled fracture network using the presented method is surveyed in comparison with modeled fracture network using Kent distribution.
    Keywords: Fracture orientation, Geostatistical modeling, Categorical simulation, Fracture set, Fracture connectivity
  • Javad Vazife Mehrabani *, Parviz Pourghahramani, Hadi Asqarian, Asghar Bagherian Pages 147-150
    In this research, selective flotation of Mo from the Sungun Cu-Mo concentrate was evaluated in different operating conditions. It was found that the addition of 16 kg/t Na2S into flotation pulp and aeration decreased rapidly the initial oxidized- reduction potential (ORP) of the pulp from to -597 mV (with reference to standard Ag/AgCl electrode) and increasing the amount of Na2S by 50kg/t did not change the pulp potential. The highest metallurgical and selective separation of Mo from Mo-Cu concentrate were achieved at pH= 10.5 and ORP
    Keywords: Cu-Mo concentrate, Nitrogen, Pulp potential, Separation efficiency, Sodium sulphide
  • Hadi Abdollahi *, Sied Ziaeddin Shafaei, Mohammad Noaparast, Zahra Manafi Pages 151-159
    This study evaluates the effects of different additives such as silver ion, medium and energy sources on the efficiency of mixed moderate thermophilic bioleaching approach to extract Cu, Mo and Re from molybdenite concentrate containing 0.98% Cu, 1.56% Fe, 53.84% Mo, and 0.055% Re. Molybdenite was the major phase of Mo-bearing mineral and chalcopyrite, covellite and pyrite were distinguished as minor phases. The higher copper extraction was obtained in tests with silver additives in all types and quantities rather than tests without silver ion. Kinetic of copper dissolution varied in these experiments and depended on the types and amounts of silver, and other supplemented additives such as ferric ion. There was no clear difference in the copper extraction by various culture media and 100% of Cu was dissolved after 30 days of treatment, using 50 mg/L of silver nitrate as additives. In the best condition and without silver additives, maximum 60% of copper was extracted even in the presence of energy sources such as sulfur, ferrous and ferric ions. In the most effective test with initial pH 1.57, 50 mg/L silver nitrate, and 50 g/L ferric sulfate, 100% of copper was dissolved in less than a week with highest kinetics rate. Molybdenum and rhenium extraction had the same tends with redox potential graph. By increasing the redox potential to the 550-600mV, molybdenite started to dissolve and finally, molybdenum and rhenium were extracted 2% and 9.53% in the best condition; respectively.
    Keywords: Bioleaching, chalcopyrite bioleaching, Mo, Re extraction, molybdenite concentrate, silver catalysis
  • Sasan Ghorbani *, Farhad Samimi Namin, Seyed Ahmad Lajevardi Pages 161-176
    One of the main challenges faced in design and construction phases of tunneling projects is the determination of maximum allowable advance step to maximize excavation rate and reduce project delivery time. Considering the complexity of determining this factor and unexpected risks associated with inappropriate determination of that, it is necessary to employ a method which is capable of accounting for interactions among uncertain geotechnical parameters and advance step. The main objective in the present research is to undertake optimization and risk management of advance step length in water diversion tunnel at Shahriar Dam based on uncertainty of geotechnical parameters following a statistic-probabilistic approach. In the present research, in order to determine optimum advance step for excavation operation, two hybrid methods were used: strength reduction method-discrete element method- Monte Carlo simulation (SRM/DEM/MCS) and strength reduction method- discrete element method- point estimate method (SRM/DEM/PEM). Moreover, Taguchi analysis was used to investigate the sensitivity of advance step to changes in statistical distribution function of input parameters under three tunneling scenarios at sections of poor to good qualities (as per RMR classification system). Final results implied the optimality of the advance step defined in scenario 2 where 2 m advance per excavation round was proposed, according to shear strain criterion and SRM/DEM/MCS, with minimum failure probability and risk of 8.05% and 75281.56 $, respectively, at 95% confidence level. Moreover, in either of normal, lognormal, and gamma distributions, as the advance step increased from Scenario 1 to 2, failure probability was observed to increase at lower rate than that observed when advance step in scenario 2 was increased to that In Scenario 3. In addition, Taguchi tests were subjected to signal-to-noise analysis and the results indicated that, considering the three statistical distributions of normal, lognormal, and gamma, under the scenario with poor section, effect of normal stiffness of joints on excavation advance step was larger than the effect of other parameters. Accordingly, with increasing RMR quality, normal stiffness of joints was seen to decrease, so that deformability modulus became more significant.
    Keywords: Advance step, SRM-DEM-MCS, SRM-DEM-PEM, Risk analysis, Taguchi
  • Ezzeddin Bakhtavar *, Reza Lotfian Pages 177-183
    The accurate selection of a processing plant site can result in decreasing total mining cost. This problem can be solved by multi-criteria decision-making (MCDM) methods. This research introduces a new approach by integrating fuzzy AHP and gray MCDM methods to solve all decision-making problems. The approach is applied in the case of a copper mine area. The critical criteria are considered adjacency to the crusher, adjacency to tailing dam, adjacency to a power source, distance from blasting sources, the availability of sufficient land, and safety against floods. After studying the mine map, six feasible alternatives are prioritized using the integrated approach. Results indicated that sites A, B, and E take the first three ranks. The separate results of fuzzy AHP and gray MCDM confirm that alternatives A and B have the first two ranks. Moreover, the field investigations approved the results obtained by the approach.
    Keywords: Fuzzy theory, gray theory, site selection, open pit mining
  • Masoud Akhyani, Farhang Sereshki, Reza Mikaeil *, Mohammad Taji Pages 185-190
    Artificial Intelligence (AI) techniques are used for solving the intractable engineering problems. In this study, it is aimed to study the application of artificial bee colony algorithm for predicting the performance of circular diamond saw in sawing of hard rocks. For this purpose, varieties of fourteen types of hard rocks were cut in laboratory using a cutting rig at 5 mm depth of cut, 40 cm/min feed rate and 3000 rpm peripheral speed. Four major mechanical and physical properties of studied rocks such as uniaxial compressive strength (UCS), Schimazek abrasivity factor (SF-a), Mohs hardness (Mh), and Young’s modulus (Ym) were determined in rock mechanic laboratory. Artificial bee colony (ABC) was used to classify the performance of circular diamond saw based on mentioned mechanical properties of rocks. Ampere consumption and wear rate of diamond saw were selected as criteria to evaluate the result of ABC algorithm. Ampere consumption was determined during cutting process and the average wear rate of diamond saw was calculated from width, length and height loss. The results of comparison between ABC’s results and cutting performance (ampere consumption and wear rate of diamond saw) indicated the ability of metaheuristic algorithm such as ABC to evaluate the cutting performance.
    Keywords: Ampere consumption, Cutting performance, Metaheuristic algorithm, Wear rate
  • Mohammad Hossein Khosravi *, Farzaneh Hamedi Azad, Mojtaba Bahaaddini, Thirapong Pipatpongsa Pages 191-197
    In this paper, the problem of a retaining wall under active translation mode is investigated numerically. To this end, a series of numerical models is conducted using the discrete element code, PFC2D. The backfill soil is simulated by an assembly of separate cohesionless circular particles. Backfill soil was prepared by pouring soil particles from a specific height under gravity force and giving them enough time for appropriate settlement. Different heights of retaining walls are simulated and the lateral earth pressure on the wall is observed under both at-rest and active conditions. Numerical results compared with predictions from some analytical methods and measurements from physical models. The active state of earth pressure is defined as the earth pressure distribution corresponding to the values of wall displacement where the failure zone in the backfill is fully developed. The numerical results showed that the fully active state of earth pressure occurred at a wall displacement corresponding to the strains required for reaching the critical state in biaxial compressive tests.
    Keywords: Numerical analysis, Retaining walls, Lateral earth pressure, PFC2D
  • Poorandokht Soltani, Mehrdad Soleimani, Hamid Aghajani * Pages 199-207
    Various approached have been introduced to extract as much as information form seismic image for any specific reservoir or geological study. Modeling of faults and fractures are among the most attracted objects for interpretation in geological study on seismic images that several strategies have been presented for this specific purpose. In this study, we have presented a modified approach of application concept of the principle components analysis to enhance faults and fractures from low quality seismic image. In the first step, relevant attributes considering imaging faults and fractures were have drawn based on vast study on previous successful applications of different attributes. Subsequently, major informative components of each attribute were defined by performing principle component analysis. Since random noise in seismic image exhibits no correlation in seismic data, true reflectors and diffraction events show high coherency value thus these objects would be separated into different orthogonal components in principle component analysis. It will make it easy to remove irrelevant information considering faults and fractures from seismic image and thus will make a higher quality image by combining attribute sections in principle component analysis. Afterwards, selected components were stacked to enhance the fault position in final image. However, since that are other geological objects that might show correlation in other orthogonal components, so there should be refinement step on the final image to stack only the favorable information. This approach was performed on a field land data example form north east of Iran. Result of application the proposed strategy shows that the method is capable to image faults compared to the conventional image analysis for fault detection. The method was also capable to image accurate position of the body of mud volcanoes exited in the image that could not be easily tracked by conventional seismic image analysis.
    Keywords: Attributes, Faults, fracture, Mud volcano, Principle component analysis, seismic