76. GIS modelling for Au-Pb-Zn potential mapping in Torud-Chah Shirin area-Iran

M. Ziaii; A. Abedi; M. Ziaei; A. Kamkar Rouhani; A. Zendahdel

Volume 1, Number 1 , Winter 2010

Abstract

  One of the major strengths of a Geographic Information System (GIS) in geosciences is the ability to integrate and combine multiple layers into mineral potential maps showing areas ...  Read More One of the major strengths of a Geographic Information System (GIS) in geosciences is the ability to integrate and combine multiple layers into mineral potential maps showing areas which are favorable for mineral exploration. These capabilities make GIS an extremely useful tool for mineral exploration. Several spatial modeling techniques can be employed to produce potential maps. However, these methods can be divided into knowledge -and data-driven techniques. The goal of this study is to use GIS in mapping gold deposit potentials in Torud-Chah Shiran area. After collecting relevant exploration data and defining appropriate exploration model for the mineralization zone, several layers including proved mineralization map, geological map, remote sensing derived, alteration map, geochemical and aeromagnetic maps were imported in to GIS environment. For integrated exploration modeling, two methods were used: fuzzy logic and weight of evidence methods. Finally, the results of the two methods were compared. The result of each method had statistical problems but these problems were alleviated using the map of differences that was in a good agreement with reality.

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77. Assessment of water quality due to Wolfram mining in Portugal

V. F. Navarro-Torres; R. N. Singh

Volume 1, Number 2 , Summer 2010

Abstract

  Water has an important role in creating pollution problems in the mining regimes influencing the surrounding surface environment. The purpose of this study is to make an assessment ...  Read More Water has an important role in creating pollution problems in the mining regimes influencing the surrounding surface environment. The purpose of this study is to make an assessment of groundwater quality in an underground mine site in Portugal with a view of determining the pollution potential of groundwater. In the corresponding surface area of this underground mine, intersections of four faults form rock blocks which delimit the surface subsidence influencing the flow pattern of the surface streams and the groundwater table resulting in inflow of groundwater and rainwater into mining excavations. When this water comes into contact with the virgin rock mass containing pyrites in presence of atmospheric air, acid mine water is formed. This acidic water reacts with the broken rock material dissolving metallic sulphides into solution and also carrying suspended solids. When discharged in the “Boldehão” River, these waters produce diverse environmental impact levels such as pH low and Zn high levels risk cause for irrigation, pH, Cu, Fe and Mn high level risk for consumption human, and pH, Cu and Zn cause high level for fishes.

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78. Application of SPI for Modeling energy consumption in Sarcheshmeh SAG and ball mills

M. Jahani; M. Noaparast; A. Farzanegan; G. Langarizadeh

Volume 2, Issue 1 , Winter 2011

Abstract

  In this research, the efficiency of the comminution circuit as well as the efficiency of size classification equipment of the concentrator plant 2 of Sarcheshmeh copper complex was ...  Read More In this research, the efficiency of the comminution circuit as well as the efficiency of size classification equipment of the concentrator plant 2 of Sarcheshmeh copper complex was studied. The comminution circuit of this plant includes one SAG mill in a closed circuit with a vibrating screen and one ball mill with a size classification system of hydrocyclone. The goal of this work was to calculate the proportion of each of these mills at energy consumption and generating suitable product for flotation as a further process. Three stages of sampling were performed and consumed energy was also modeled. The average efficiency of the initial ball mill was obtained which was equal to 72.96%. The average of the proportion of (consumed) energy by SAG and ball mills from total consumed energy at mills, was 44.65% and 55.35% respectively. The proportion of SAG and ball mills in producing the final product (particles finer than 74 µm) was 55.38% and 44.62% respectively. That is, the SAG mill produces about 10.76% more than the ball mill in the final product. The average consumed energy at SAG and ball mills to produce one ton of final product was 23.16 kWh/t and 36.05 kWh/t respectively. Thus, the ball mill consumes 12.89 kWh/t, more energy than the SAG mill in producing the final product. The average cyclones’ imperfection was 0.361 and therefore the average efficiency of cyclones’ separation was equal to 63.9% and the average efficiency of the vibrating screen was equal to 99.89%. As overflow of the initial cyclones (final product of comminution circuit) forms feed of rougher cells, cyclones’ inappropriate performance could severely influence the whole flotation process.

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79. Subsurface modeling of mud volcanoes, using density model and analysis of seismic velocity

H.R Baghzendani; H. Aghajani; M. Solimani

Volume 6, Issue 1 , Winter 2015, , Pages 31-39

Abstract

  Detection of subsurface structures by means of gravity method can be used to determine mass distribution and density contrast of rock units. This distribution could be detected by different ...  Read More Detection of subsurface structures by means of gravity method can be used to determine mass distribution and density contrast of rock units. This distribution could be detected by different geophysical methods, especially gravity method. However, gravity techniques have some drawbacks and can't be always successful in distinguishing subsurface structures. Performance of the gravity technique could be further improved by simultaneous combination and introducing additional information from other geophysical data. This study used existing relation between seismic and gravity methods to better clarify subsurface structures. This relationship relates mass distribution of the medium to velocity of wave propagation in that media. This method was applied on an area that consists of three mud volcanoes. After completion of the primary model by forward modeling, mass distribution and analysis of seismic velocity were provided on a 2-D profile. Bouguer anomaly map of gravity data of the area was obtained and negative anomalies were identified. These negative anomalies could be related to the existence of mud volcanoes. A 2-D seismic line was also acquired over the greatest mud volcano, as additional information for direct modeling. The Gardner equation was used for further velocity estimation by density values. This velocity model also compared with seismic velocity analysis for evaluation. The final results indicated that density modeling and the use of seismic velocity model increases the resolution of subsurface structures imaging. Separation of subsurface layers was implemented correctly in the velocity model resulting from gravity data and subsurface discontinuities of the area that become more obvious by this technique.

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80. Back-calculation of mechanical parameters of shell and balls materials from discrete element method simulations

Akbar farzanegan; Bahareh Arabzadeh; Vahid Hasanzadeh

Volume 3, Issue 1 , Winter 2012, , Pages 33-40

Abstract

  Discrete Element Method (DEM) is extensively used for mathematical modeling and simulating the behavior of discrete discs and discrete spheres in two and three dimensional space, respectively. ...  Read More Discrete Element Method (DEM) is extensively used for mathematical modeling and simulating the behavior of discrete discs and discrete spheres in two and three dimensional space, respectively. Prediction of particles flow regime, power draw and kinetic energy for a laboratory or an industrial mill is possible by DEM simulation. In this article, a new approach was used to assess the main parameters of a transparent ball mill constructed in mineral processing laboratory of the University of Tehran. The mill shell and crushing balls are made of Plexiglas® and compressed glass respectively. The true values of mechanical parameters for these materials, required for DEM modeling, were unknown. The authors back-calculated the best values of mechanical properties of Plexiglas and compressed glass materials based on a large number of DEM simulations. Back-calculation procedure was mainly based on the comparison between electrical power draw measured in real mill and mechanical power draw calculated by DEM model while trying to simulate particle flow regime inside the real mill accurately. The results showed that the optimal number and design of lifters can be adequately determined by improving torque and kinetic energy in crushing elements through DEM simulation trials based on the back-calculated mechanical parameters.

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81. Prediction of the deformation modulus of rock masses using Artificial Neural Networks and Regression methods

Javad Gholamnejad; HamidReza Bahaaddini; Morteza Rastegar

Volume 4, Issue 1 , Winter 2013, , Pages 35-43

Abstract

  Static deformation modulus is recognized as one of the most important parameters governing the behavior of rock masses. Predictive models for the mechanical properties of rock masses ...  Read More Static deformation modulus is recognized as one of the most important parameters governing the behavior of rock masses. Predictive models for the mechanical properties of rock masses have been used in rock engineering because direct measurement of the properties is difficult due to time and cost constraints. In this method the deformation modulus is estimated indirectly from classification systems. This paper presents the results of a study into the application of Artificial Neural Networks (ANN) technique and Regression models for estimation of the deformation modulus of rock masses. A database, including 225 actual measured deformation modulus, Uniaxial Compressive Strengths of the rock (UCS), and Rock Mass Rating (RMR) was established. Data collected from different projects. For predicting Em by regression, a nonlinear regression method was chosen. This model showed the coefficient correlation of 0.751 and mean absolute percentage error (MAPE) of 9.911%. Also a three-layer ANN was found to be optimum, with an architecture of two neurons in the input layer, four neurons in the hidden layer and one neuron in the output layer. The correlation coefficient determined for deformation modulus predicted by the ANN was 0.786 and the quantity of MAPE was 6.324%. With respect to the results obtained from two models, the ANN technique was shown to be better than the regression model because of its higher accuracy.

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82. Magnitude of vibration triggering component determines safety of structures

SUJIT KUMAR MANDAL; N.K Bhagat; M.M Singh

Volume 5, Issue 1 , Winter 2014, , Pages 35-46

Abstract

  Transmission of blast waves is a complex phenomenon and the characteristics vary with blast design parameters and geo-technical properties of medium. Frequency of vibration and triggering ...  Read More Transmission of blast waves is a complex phenomenon and the characteristics vary with blast design parameters and geo-technical properties of medium. Frequency of vibration and triggering component for structural excitation generally quantifies safe vibration magnitude. At closer distance or higher elevations than the blast locations, vertical or transverse component will be the first arrival to trigger the sensor for monitoring and at far off distances longitudinal component triggers the sensor to monitor. Similarly, for shorter depth of blastholes and wider blast geometries, vertical or transverse component triggers the sensor to monitor even for longer distances of measurement. Analyzing the cause of such occurrence, the paper firstly puts forward a mathematical model to illustrate the same. Thereafter, considering single-degree of freedom for dynamic analysis of structures, the paper communicates that incident particle velocity exiting a structure to vibrate should be considered to limit vibration magnitude for safety of structures.

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83. Development of a mechanical earth model in an Iranian off-shore gas field

E. Bozorgi; D. Javani; M. Rastegarnia

Volume 7, Issue 1 , Winter 2016, , Pages 37-46

Abstract

  Wellbore instability is a quite common event during drilling, and causes many problems such as stuck pipe and lost circulation. It is primarily due to the inadequate understanding of ...  Read More Wellbore instability is a quite common event during drilling, and causes many problems such as stuck pipe and lost circulation. It is primarily due to the inadequate understanding of the rock properties, pore pressure, and earth stress environment prior to well construction. This study aims to use the existing relevant logs, drilling, and other data from offset wells to construct a precise mechanical earth model (MEM) describing the pore pressure, stress magnitudes and orientations, and formation mechanical properties of South Pars Gas field. Since the core test data, MDT/XPT data, and LOT/XLOT data were not available to calibrate the developed model, each component of the model was determined using a range of existing methods and relations, and then the wellbore instability was analyzed based on the developed MEM and the Mogi-Coulomb failure criterion. The predicted incidents such as the lost circulation and tight hole were then compared with the caliper log and reported drilling events to determine the consistency of the model. Since the stability analysis based on the developed MEM had the most agreement with the caliper log and reported drilling events, the equations presented by Eaton and Zoback had good estimations of the pore pressure and rock strengths. Also the estimated horizontal stresses were precise enough to enable the constructed MEM to predict the wellbore instabilities. The stress regime in the field of study was strike-slip, which is frequently specified in the industrial technical reports of the studied field. Finally, it was concluded that the Mogi-Coulomb failure criterion minimized the conservative nature of the mud pressure prediction due to the consideration the strengthening effect of the intermediate stress.

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84. A new model for mining method selection based on grey and TODIM methods

H. Dehghani; A. Siami; P. Haghi

Volume 8, Issue 1 , Winter 2017, , Pages 49-60

Abstract

  One of the most important steps involved in mining operations is to select an appropriate extraction method for mine resources. After choosing the extraction method, it is usually impossible ...  Read More One of the most important steps involved in mining operations is to select an appropriate extraction method for mine resources. After choosing the extraction method, it is usually impossible to replace it with another one because it may be so expensive that implementation of the entire project could be economically impossible. Choosing a mining method depends on the geological and geometrical characteristics of the mine. Due to the complexity of the process of choosing an appropriate mining method and the effect of the parameters involved on the results of this process, it is necessary to utilize the new decision-making methods that have the ability to consider the relationship between the existing parameters and the mining methods. Grey and TODIM (an acronym in Portuguese, i.e. Tomada de Decisão Interativa Multicritério) decision-making methods are among the existing ones, which in addition to the convenience, show high accuracy. The proposed models are presented to determine the best mining method in the Gol-e-gohar iron ore mine in Iran. The results obtained are compared with the methods used in the previous research works. Among the decision-making methods introduced, the open pit mining method is the most appropriate option and the square-set mining is the worst one.

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85. Identification of geochemical anomalies associated with Cu mineralization by applying spectrum-area multi-fractal and wavelet neural network methods in Shahr-e-Babak mining area, Kerman, Iran

B. Shokouh Saljoughi; A. Hezarkhani

Volume 10, Issue 1 , Winter 2019, , Pages 49-73

Abstract

  The Shahr-e-Babak district, as the studied area, is known for its large Cu resources. It is located in the southern side of the Central Iranian volcano–sedimentary complex in ...  Read More The Shahr-e-Babak district, as the studied area, is known for its large Cu resources. It is located in the southern side of the Central Iranian volcano–sedimentary complex in SE Iran. Shahr-e-Babak is currently facing a shortage of resources, and therefore, mineral exploration in the deeper and peripheral spaces has become a high priority in this area. This work aims to identify the geochemical anomalies associated with the Cu mineralization using the Spectrum–Area (S–A) multi-fractal and Wavelet Neural Network (WNN) methods. At first, the Factor Analysis (FA) is applied to integrate the multi-geochemical variables of a regional stream sediment dataset related to major mineralization elements in the studied area. Then the S–A model is applied to decompose the mixed geochemical patterns obtained from FA and compare with the results obtained from the WNN method. The S–A model, based on the distinct anisotropic scaling properties, reveals the local anomalies due to the consideration of the spatial characteristics of the geochemical variables. Most of the research works show that the capability (i.e. classification, pattern matching, optimization, and prediction) of an ANN considering its successful application is suitable for inheriting uncertainties and imperfections that are found in mining engineering problems. In this paper, an alternative method is presented for mineral prospecting based on the integration of wavelet theory and ANN or wavelet network. The results obtained for the WNN method are in a good agreement with the known deposits, indicating that the WNN method with Morlet transfer function consists of a highly complex ability to learn and track unknown/undefined complicated systems. The hybrid method of FA, S–A, and WNN employed in this work is useful to identify anomalies associated with the Cu mineralization for further exploration of mineral resources.

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86. A Comparative Study of SVM and RF Methods for Classification of Alteration Zones Using Remotely Sensed Data

N. Mahvash Mohammadi; A. Hezarkhani

Volume 11, Issue 1 , Winter 2020, , Pages 49-61

Abstract

  Identification and mapping of the significant alterations are the main objectives of the exploration geochemical surveys. The field study is time-consuming and costly to produce the ...  Read More Identification and mapping of the significant alterations are the main objectives of the exploration geochemical surveys. The field study is time-consuming and costly to produce the classified maps. Therefore, the processing of remotely sensed data, which provide timely and multi-band (multi-layer) data, can be substituted for the field study. In this study, the ASTER imagery is used for alteration classification by applying two new methods of machine learning, including Random Forest and Support Vector Machine. The 14 band ASTER and 19 derivative data layers extracted from ASTER including band ratio and PC imagery, are used as training datasets for improving the results. Comparison of analytical results achieved from the two mentioned methods confirmed that the SVM model has sufficient accuracy and more powerful performance than RF model for alteration classification in the study area.

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87. Simulation of tunnel boring machine utilization: A case study

S. Moosazadeh; H. Aghababaie; Seyed H. Hoseinie; B. Ghodrati

Volume 9, Issue 1 , Winter 2018, , Pages 53-60

Abstract

  Utilization is one of the main managerial factors that is applied for construction process analysis well. It directly affects the project duration and construction costs. Therefore, ...  Read More Utilization is one of the main managerial factors that is applied for construction process analysis well. It directly affects the project duration and construction costs. Therefore, a utilization study in tunneling projects is essential. In this work, the utilization of an earth pressure balance Tunnel Boring Machine (TBM) in Tabriz urban railway project was studied using the Monte Carlo simulation approach. For this purpose, the unit operation during one working shift such as boring time, ring building time, and locomotive travel time was recorded and saved in data base. In addition, the general down times such as TBM and back-up system maintenance, surface and tunnel logistic maintenance, cutting tools’ replacement, and locomotive delay times were recorded and considered in simulation. The results of this work show that the mean simulated project duration time of case study TBM is approximately 859 shifts and close to the real data with a difference of 0.92%. Finally, the average estimated utilization factor was found to be approximately 14%.

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88. Collectorless flotation of Chalcocite by controlling redox potential

sima razmjouee; mahmood abdollahy; seyed mohammad javad koleini

Volume 3, Issue 2 , Summer 2012, , Pages 99-102

Abstract

  Using microflotation method, this study explored the collectorless flotation of Chalcocite and its dependence on the redox potential of pulp . Electrochemical studies were performed ...  Read More Using microflotation method, this study explored the collectorless flotation of Chalcocite and its dependence on the redox potential of pulp . Electrochemical studies were performed by cyclic voltammetry  in specific potential ranges and at different pH values. The results show that significant floatability of Chalcocite occurs in the specific reducing conditions. By increasing potentials, on the other hand, the floatability of Chalcocite is reduced. The effect of pH was also examined: At pH=4, the maximum recovery of 73%, was obtained at E= -222 mV (Eh= -17); and at pH=9, the maximum recovery of 71% was obtained at E= -501 mV (Eh= -296). On the basis of the results obtained, the possible mechanisms of collectorless flotation of Chalcocite in different conditions were discussed.

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89. Pit lakes as an end use of mining: A review

Anhay Soni; B. Mishra; Siddharth Singh

Volume 5, Issue 2 , Summer 2014, , Pages 99-111

Abstract

  Theoretical review of ‘mining pit lakes’ indicates that like natural lakes such lakes display a huge diversity. They are typically in a non-equilibrium state with respect ...  Read More Theoretical review of ‘mining pit lakes’ indicates that like natural lakes such lakes display a huge diversity. They are typically in a non-equilibrium state with respect to their surroundings. Hence, at the decommissioning phase of mining operation a detailed technical study are required on different aspects of such created water bodies considering its morphometry, geology, hydrology, water quality (geo-chemistry), rate of filling, and biology. Pit lakes has their value as resources for miscellaneous purposes e.g. recreation, fisheries, water supply, and wildlife habitat which is dependent mostly on their topography, location water use and safety characteristics. Internationally, pit lakes as self sustaining aquatic ecosystems have been developed in the past e.g. Alberata Pit Lake in Canada [1, 2] ; Sleeper pit lake [3] and Westfield pit lake, Scotland [4]. In Indian mining industry neither scientific studies nor case record of mining pit lake development are available because ‘closure plans’ are introduced recently. One such attempt in India at Kerendari coal mine in Jharkhand state is a laudable and new attempt which is at the stage of planning. In brief, since the opportunities for development of ‘mining pit lakes’ are immense and company owning it can nurture their ecological and commercial benefits appropriately, this review will be practically useful particularly in those countries which has less number of age old surface mines heading towards the decommissioning phase. The review done here can be practically utilized for evaluation, assessment, new project clearances and statuary compliance purposes.

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90. A new algorithm for optimum open pit design: Floating cone method III

ebrahim elahi; Reza Kakaie; amir yusefi

Volume 2, Issue 2 , Summer 2011, , Pages 118-125

Abstract

  Ultimate limits of an open pit, which define its size and shape at the end of the mine’s life, is the pit with the highest profit value. A number of algorithms such as floating ...  Read More Ultimate limits of an open pit, which define its size and shape at the end of the mine’s life, is the pit with the highest profit value. A number of algorithms such as floating or moving cone method, floating cone method II and the corrected forms of this method, the Korobov algorithm and the corrected form of this method, dynamic programming and the Lerchs and Grossmann algorithm based on graph theory have been developed to find out the optimum final pit limits. Each of these methods has special advantages and disadvantages. Among these methods, the floating cone method is the simplest and fastest technique to determine optimum ultimate pit limits to which variable slope angle can be easily applied. In contrast, this method fails to find out optimum final pit limits for all the cases. Therefore, other techniques such as floating cone method II and the corrected forms of this method have been developed to overcome this shortcoming. Nevertheless, these methods are not always able to yield the true optimum pit. To overcome this problem, in this paper a new algorithm called floating cone method III has been introduced to determine optimum ultimate pit limits. The results show that this method is able to produce good outcome.

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91. An applied comparison between conventional pre-dispersed solvent extraction (PDSE) contactors and new dissolved nitrogen PDSE (DNPDSE) ones

M. R. Tavakoli Mohammadi; Seyed M. J. Koleini; M. Abdollahy

Volume 6, Issue 2 , Summer 2015, , Pages 159-168

Abstract

  Efforts to increase the mass transfer coefficient, enhance the contact area, and decrease the power input of contractors have given risen to the development of the pre-dispersed solvent ...  Read More Efforts to increase the mass transfer coefficient, enhance the contact area, and decrease the power input of contractors have given risen to the development of the pre-dispersed solvent extraction (PDSE) contactor and the devise of the new dissolved nitrogen PDSE (DNPDSE) contactors. The studies conducted after the design of the new contactor to determine the working conditions for its suitable performance (2.5-3.5 bar pressure, 0.1 L/min sparger flow rate, and 1.5 L of the aqueous phase) showed that for all the evaluated conditions (i.e. the pressure, polyaphron type, and dilution percentage), the recovery in the DNPDSE contactor was higher than that in the PDSE one. In addition, pictures of the performance modes of the two contactor indicated the presence of the organic phase in the form of colloidal gas aphrons (CGAs) in the DNPDSE contactor and of polyaphron aggregations in the PDSE one. This is a good reason for the increased copper recovery in the DNPDSE contactor. The best recovery for the extraction process in the DNPDSE contactor was achieved using the anionic polyaphron of sodium dodecylbenzene sulphonate (NaDBS) with five-fold dilution at 3.5 bar.

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92. Prediction of slope stability using adaptive neuro-fuzzy inference system based on clustering methods

H. Fattahi

Volume 8, Issue 2 , Spring 2017, , Pages 163-177

Abstract

  Slope stability analysis is an enduring research topic in the engineering and academic sectors. Accurate prediction of the factor of safety (FOS) of slopes, their stability, and their ...  Read More Slope stability analysis is an enduring research topic in the engineering and academic sectors. Accurate prediction of the factor of safety (FOS) of slopes, their stability, and their performance is not an easy task. In this work, the adaptive neuro-fuzzy inference system (ANFIS) was utilized to build an estimation model for the prediction of FOS. Three ANFIS models were implemented including grid partitioning (GP), subtractive clustering method (SCM), and fuzzy c-means clustering method (FCM). Several important parameters such as cohesion coefficient, internal angle of friction, slope height, slope angle, and unit weight of slope material were utilized as the input parameters, while FOS was used as the output parameter. A comparison was made between these three models, and the results obtained showed the superiority of the ANFIS-SCM model. Also performance of the ANFIS-SCM model was compared with multiple linear regression (MLR). The results obtained demonstrated the effectiveness of the ANFIS-SCM model.

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93. Application of stochastic programming for iron ore quality control

J. Gholamnejad; A. Azimi; M.R. Teymouri

Volume 9, Issue 2 , Spring 2018, , Pages 331-338

Abstract

  Stockpiling and blending play a major role in maintaining the quantity and quality of the raw materials fed into processing plants, especially the cement, iron ore and steel making, ...  Read More Stockpiling and blending play a major role in maintaining the quantity and quality of the raw materials fed into processing plants, especially the cement, iron ore and steel making, and coal-fired power generation industries that usually require a much uniformed feed. Due to the variable nature of such materials, they even come from the same source and the produced ores or concentrates are seldom homogeneous enough to be directly fed to the processing plant ore furnaces. Processing plants in iron ore mines need uniform feed properties in terms of each variable (in this work, iron phosphorous ratio and Fe content in magnetite phase) grade of ore, and therefore, homogenization of iron ore from different benches of an open pit or ore dumps has become an essential part of modern mine scheduling. When ore dumps are considered as an ore source, the final grade of the material leaving the dump to the blending bed cannot be easily determined. This difficulty contributes to mixing the materials of different grades in a dump. In this work, the ore dump elements were treated as normally distributed random variables. Then a stochastic programming model was formulated in an iron ore mine in order to determine the optimum amount of ore dispatched from different bench levels in open pit and also four ore dumps to a windrow-type blending bed in order to provide a mixed material of homogenous composition. The chance-constrained programming technique was used to obtain the equivalent deterministic non-linear programming problem of the primary model. The resulting non-linear model was then solved using LINGO. The results obtained showed a better feed grade for the processing plant with a higher probability of grade blending constraint satisfaction.

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94. Application of fractal modeling to delineate alteration zones and lithological units in Masjed-Daghi Cu-Au porphyry deposit, NW Iran

H. Nikoogoftar Safa; A. Hezarkhani

Volume 10, Issue 2 , Spring 2019, , Pages 339-356

Abstract

  In this paper, we aim to present a quantitative modeling for delineating the alteration zones and lithological units in the hypogene zone of Masjed-Daghi Cu-Au porphyry deposit (NW ...  Read More In this paper, we aim to present a quantitative modeling for delineating the alteration zones and lithological units in the hypogene zone of Masjed-Daghi Cu-Au porphyry deposit (NW Iran) based on the drill core data. The main goal of this work is to apply Ordinary Kriging (OK) and concentration-volume (C-V) fractal model based on Cu grades in order to separate the different alteration zones and lithological units. Initially, anisotropy was investigated and modeled based on calculating the experimental semi-variograms of the Cu values, and the main variography directions were identified and evaluated. Then a block model of the Cu grades was generated using the kriging, and the estimation obtained for OK was applied to the C-V fractal model. The C–V log–log plot based on the estimation method represents the various alteration and lithological zones via threshold values. The comparison and interpretation of the alteration zones and lithological units based on the C–V fractal modeling proved that the method was acceptable and capable of correctly delineating the alteration and lithological units. Regarding the correlation derived from log ratio matrix (used to compare the geological model with the C-V fractal results), it was observed that Cu values less than 0.4% were obtained for OK overlapped voxels with the phyllic alteration zone by an overall accuracy (OA) of 0.737. The spatial correlation between the potassic alteration zones resulting from a 3D geological modeling and the high concentration zones in the C-V fractal model based on OK indicated that the alteration zone contained Cu values greater than 0.4% with OA of 0.791. Also using this method, trustworthy results were obtained for the rock units.

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95. A new method to consider spatial risk assessment of cross-correlated heavy metals using geo-statistical simulation

M. Sakizadeh; M. T. Sattari; H. Ghorbani

Volume 8, Issue 3 , Summer 2017, , Pages 373-391

Abstract

  The soil samples were collected from 170 sampling stations in an arid area in Shahrood and Damghan, characterized by prevalence of mining activity. The levels of Co, Pb, Ni, Cs, Cu, ...  Read More The soil samples were collected from 170 sampling stations in an arid area in Shahrood and Damghan, characterized by prevalence of mining activity. The levels of Co, Pb, Ni, Cs, Cu, Mn, Sr, V, Zn, Cr, and Tl were recorded in each sampling location. A new method known as min/max autocorrelation factor (MAF) was applied for the first time in the environmental research works to de-correlate these elements before their geo-statistical simulation. The high cross-correlation among some elements, while poor spatial correlation among the others, could have made spectral decomposition of MAFs unstable, resulting in some negative eigenvalues, so it was decided to reduce the dimensionality of the original variables by Principal Component Analysis (PCA). The resultant 6 heavy metals (Cr, Mn, Cu, V, Ni, and Co) were converted to their respective MAFs followed by their geo-statistical simulation using Sequential Gaussian Simulation (SGS) independently. Examination of the cross-variograms of MAFs indicated that the resultant factors had been rigorously de-correlated, especially at zero lag and around ∆ lag distance. Several validation checks including reproduction of variograms in data and normal score space, close matching between distribution of MAFs versus simulated realizations, and reproduction of descriptive statistics and data histograms all confirmed that the data values had been honored by this applied method. The results obtained indicated that this method could reproduce the data values as well as the spatial continuity of heavy metals (e.g. semi-variograms) successfully. In addition, this technique is simpler and more computationally efficient than its equivalent sequential Gaussian co-simulation as fitting a linear model of co-regionalization (LMC) is not required in the data-driven MAF method.

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96. Development of Geometallurgical Indices for Semi-Autogenous Grinding at Sarcheshmeh Porphyry Copper Mine

S. Mohammadi; B. Rezai; A. A. Abdolahzadeh

Volume 11, Issue 2 , Spring 2020, , Pages 375-385

Abstract

  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 ...  Read More 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.

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97. Sub-pixel classification of hydrothermal alteration zones using a kernel-based method and hyperspectral data; A case study of Sarcheshmeh Porphyry Copper Mine and surrounding area, Kerman, Iran

A. Salimi; M. Ziaii; A. Amiri; M. Hosseinjani Zadeh

Volume 8, Issue 4 , Autumn 2017, , Pages 555-565

Abstract

  Remote sensing image analysis can be carried out at the per-pixel (hard) and sub-pixel (soft) scales. The former refers to the purity of image pixels, while the latter refers to the ...  Read More Remote sensing image analysis can be carried out at the per-pixel (hard) and sub-pixel (soft) scales. The former refers to the purity of image pixels, while the latter refers to the mixed spectra resulting from all objects composing of the image pixels. The spectral unmixing methods have been developed to decompose mixed spectra. Data-driven unmixing algorithms utilize the reference data called training samples and end-members. The performance of algorithms using training samples can be negatively affected by the curse of dimensionality. This problem is usually observed in the hyperspectral image classification, especially when a low number of training samples, compared to the large number of spectral bands of hyperspectral data, are available. An unmixing method that is not highly impressed by the curse of dimensionality is a promising option. Among all the methods used, Support Vector Machine (SVM) is a more robust algorithm used to overcome this problem. In this work, our aim is to evaluate the capability of a regression mode of SVM, namely Support Vector Regression (SVR), for the sub-pixel classification of alteration zones. As a case study, the Hyperion data for the Sarcheshmeh, Darrehzar, and Sereidun districts is used. The main classification steps rely on 20 field samples taken from the Darrehzar area divided into 12 and 8 samples for training and validation, respectively. The accuracy of the sub-pixel maps obtained demonstrate that SVR can be successfully applied in the curse of dimensional conditions, where the size of the training samples (12) is very low compared to the number of spectral bands (165).

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98. A GIS-aided resource estimation of coalfields in Kangal basin, Sivas province, Turkey

B. A. Mert

Volume 9, Issue 3 , Summer 2018, , Pages 581-591

Abstract

  This paper presents the procedures used for determining and defining the tonnage and grade of the coalfields of Kangal basin from the developed GIS-aided block model. In this work, ...  Read More This paper presents the procedures used for determining and defining the tonnage and grade of the coalfields of Kangal basin from the developed GIS-aided block model. In this work, firstly, all the lithological logs of drill holes and chemical analysis data of core in the basin were analyzed with the help of geostatistics, and then the digital raster maps of each one of the attributes such as the thickness, calorific value (LCV), ash content (AC%), moisture content (MC%), and surface maps of lignite seams were mapped in GIS environment. In the second stage, quantities of the overburden and resources with different categories were calculated on the basis of field-based quality and volume queries with the help of the digital maps on GIS platform. As a result, it was estimated that the Kalburçayırı field had a tonnage of 116 Mt of lignite with an LCV of 1308 kcal/kg, the Hamal field had a tonnage of 30 Mt of lignite with an LCV of 987 kcal/kg, and the Etyemez field had a tonnage of 48 Mt of lignite with an LCV of 1282 kcal/kg. Also it was estimated that almost 24,278,151 tons of lignite in the Hamal and Etyemez fields had a quality of less than 950 kcal/kg that could be directly fired without the blending process in the power plant. As a consequence, the Hamal and Etyemez fields should go into production as soon as possible and be fired in the power plant after being mixed with the lignite in the Kalburcayırı field so that they can be redounded to economy.

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99. Determination of optimal bandwidth in upscaling process of reservoir data using kernel function bandwidth

M. R. Azad; A. Kamkar Rouhani; B. Tokhmechi; M. Arashi

Volume 10, Issue 3 , Summer 2019, , Pages 613-621

Abstract

  Upscaling based on the bandwidth of the kernel function is a flexible approach to upscale the data because the cells will be coarse-based on variability. The intensity of the coarsening ...  Read More Upscaling based on the bandwidth of the kernel function is a flexible approach to upscale the data because the cells will be coarse-based on variability. The intensity of the coarsening of cells in this method can be controlled with bandwidth. In a smooth variability region, a large number of cells will be merged, and vice versa, they will remain fine with severe variability. Bandwidth variation can be effective in upscaling results. Therefore, determining the optimal bandwidth in this method is essential. For each bandwidth, the upscaled model has a number of upscaled blocks and an upscaling error. Obviously, higher thresholds or bandwidths cause a lower number of upscaled blocks and a higher sum of squares error (SSE). On the other hand, using the smallest bandwidth, the upscaled model will remain in a fine scale, and there will be practically no upscaling. In this work, different approaches are used to determine the optimal bandwidth or threshold for upscaling. Investigation of SSE changes, the intersection of two charts, namely SSE and the number of upscaled block charts, and the changes of SSE values versus bandwidths, are among these approaches. In this particular case, if the goal of upscaling is to minimize the upscaling error, the intersection method will obtain a better result. Conversely, if the purpose of upscaling is computational cost reduction, the SSE variation approach will be more appropriate for the threshold setting.

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100. A new 2D block ordering system for wavelet-based multi-resolution up-scaling

B. Tokhmechi; M. Rabiei; H. Azizi; V. Rasouli

Volume 9, Issue 4 , Autumn 2018, , Pages 817-828

Abstract

  A complete and accurate analysis of the complex spatial structure of heterogeneous hydrocarbon reservoirs requires detailed geological models, i.e. fine resolution models. Due to the ...  Read More A complete and accurate analysis of the complex spatial structure of heterogeneous hydrocarbon reservoirs requires detailed geological models, i.e. fine resolution models. Due to the high computational cost of simulating such models, single resolution up-scaling techniques are commonly used to reduce the volume of the simulated models at the expense of losing the precision. Several multi-scale techniques have also been developed for simulating heterogeneous reservoirs including those in which a limited number of blocks down-scale, i.e. splitting coarse blocks into fine cells around the well-zones in the case of simulation of hydraulic fracturing. In these cases, locally computed basis functions are employed to construct a global solver at a coarse-scale such as wavelet- and kernel-based up-scaling techniques. In this paper, a novel/robust 2D block-ordering system is presented, which enables solving multi-resolution up-scaling fluid flow simulations. The results will be described for a simple model, and fluid flow equations will be developed in order to show the structure of transmissibility matrix. It is confirmed that with a developed block-ordering system not only the accuracy of history match increases but also the CPU time decreases.

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