فهرست مطالب

Mining & Geo-Engineering - Volume:53 Issue:1, 2019
  • Volume:53 Issue:1, 2019
  • تاریخ انتشار: 1398/01/31
  • تعداد عناوین: 12
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  • Abdolmotaleb Hajati, Ziaedine Shafaei *, Mohammad Noaparast, Saeed Farrokhpay, Soheila Aslani Pages 1-6
    In this study, hydrophobic talc nanoparticles were applied as a novel class of solid flotation collector. The aim of this work was to understand the effect of talc nanoparticles size and dosage on the quartz flotation recovery. X-ray analysis, dynamic light scattering, and scanning electron microscopy were conducted. Flotation tests were performed in modified a Hallimond flotation cell. The Zeta potential measurement identified the pH value of 1.5 as the best condition for nano-talc powders to be electrostatically adsorbed on the quartz particle surfaces. Talc particles were adsorbed onto the hydrophilic quartz particles to encourage the air bubble attachment and improve the quartz flotation recovery. It was found that as the quartz particle size decreased, the amount of quartz flotation recovery increased. Talc size reduction from 567 nm to 235 nm, decreased the amount of required talc from 45 to 1.7 kg/t within 30 minutes of the flotation time span, and achieved a recovery of more than 90%. Practically, it was demonstrated that by using smaller talc nanoparticles, it was possible to decrease the talc dosage to obtain a similar level of quartz recovery over the same flotation time span and pH.
    Keywords: Flotation, Quartz, Talc nanoparticles, Solid collector
  • Saleh Nosrati, Kumars Seifpanahi *, Mohammad Karamoozian Pages 7-13
    Adsorption of lead(II) as a major heavy metal pollutant onto nano-adsorbents of Andalusite, Kyanite and Sillimanite was studied in a batch system. Nano -adsorbents were prepared via crushing, using a planetary ball mill and then characterized by different analyses such as: SEM, XRD, XRF and FT-IR. Major factors affecting the adsorption process were studied including pH, adsorbents dosage, initial metal concentration and temperature. Afterward, the adsorption process was studied isothermally, kinetically, and thermodynamically. The results show that aluminum silicates polymorphs are efficient adsorbents for removal of lead(II) and the removal exceeds 90%. The Freundlich isotherm model was best fitted with the experimental data. Chemisorption may control the rate of adsorption due to following the pseudo-second-order kinetic model. Thermodynamic investigation proved low randomness, exothermic and spontaneous nature of the process.
    Keywords: Andalusite, Kyanite, Sillimanite, Adsorption, Lead(II) ion
  • Saleh Ghadernejad *, Amir Jafarpour, Pouya Ahmadi Pages 15-23
    Increasing the production rate and minimizing the related costs, while optimizing the safety measures, are nowadays’ most important tasks in the mining industry. To these ends, mechanization of mines could be applied, which can result in significant cost reductions and higher levels of profitability for underground mines. The potential of a coal mine mechanization depends on some important factors such as seam inclination and thickness, geological disturbances, seam floor and roof conditions. Mechanization of underground mines requires substantial investments. Therefore, thorough inspection of pertaining aspects is of highest importance before a final decision. The main aim of this study is to develop a new approach to rank the mechanization potential of different coal seams in the Tazareh coal mine complex based on multi-criteria decision-making methods. In fact, a decision-making approach is an effective tool for dealing with complex decision-making processes, and the obtained results may aid the decision maker to determine the priorities and make the best decision. To this end, an integrated Fuzzy Delphi Analytical Hierarchy Process (FDAHP) - PROMETHEE method was utilized to rank coal stopes from the best to the worst. Among different coal seams, K19 was selected as the optimal alternative for mechanization of the Tazareh coal mine complex. In addition, in order to investigate the effects of the pertaining factors on the final decision, a sensitivity analysis was performed. The results obtained from sensitivity analysis showed that K19 with 71.4% of votes had the highest potential for mechanization.
    Keywords: Coal Mine, Mechanization Potential, FDAHP, PROMETHEE method, Optimal Selection
  • Fatemeh Kazemi, Ataallah Bahrami *, Jafar Abdollahisharif Pages 25-31
    Kinetic models are the most important tools for the prediction and evaluation of the flotation circuits performance. In order to determine the kinetic order and rate of flotation of a Gilsonite sample, flotation experiments were conducted using the combination of Gasoline-Pine Oil, and one test without any collector and frother. The pulp density was 10% and the experiments were carried out in both rougher and cleaner stages using different size fractions. Five first order kinetic models were applied to the data obtained from the flotation tests by using the Matrix Laboratory software. Statistical analysis demonstrated that the results of Gasoline-Pine Oil experiment have a high degree of compliance with the all models. Rougher and cleaner tests without collector and frother also matched with the modified gas/solid adsorption and rectangular models with the k values of 0.0869 (s-1), and 0.0266 (s-1), respectively. The relationship between flotation rate constant, maximum combustible recovery and particle size were also studied. The results showed that the maximum flotation combustible recovery and flotation rate were obtained with an intermediate particle size in the rougher flotation processes. The maximum combustible recovery and flotation rate in the cleaner flotation process was related to the particle size categories of -850+500 (μm) and -500+250 (μm), respectively.
    Keywords: Rate of flotation, Kinetic models, Gilsonite, Combustible recovery, Size of particles
  • Pouya Karimi, Hadi Abdollahia *, Ziaedine Shafaei, Aysan Molaei Pages 33-41
    The present study addresses the direct flotation route for the concentration of a zinc silicate ore. Flotation of hemimorphite faces some challenges due to the similarity of hemimorphite and quartz surface properties. XRD, and XRF analyses, optical mineralogy and SEM with X-ray mapping were performed for characterization. The results showed that the quartz, hemimorphite, calcite and dolomite are the main minerals. In the flotation process, combined form of Octadecylamine and Armac T, as mixed cationic collectors were introduced. Flotation tests were employed in two steps to evaluate the individual effect of the variables such as: size distribution of feed and the presence of Armac T in the first step, alkalinity, types and concentrations of reagents (Armac T and stearyl amine (collectors), sodium sulfide (sulphidizing agent), and sodium hexametaphosphate (dispersant) in the second step. In optimal conditions, the grade and recovery of zinc in concentrate were ~33 % and 83 %, respectively. Finally, for removing the detrimental effect of fine particles, de-sliming of pulp feed accomplished which resulted in a remarkable increase in the recovery of hemimorphite concentrate (12.67%) and a decrease in the grade of zinc in tailing (6.11%). FTIR analysis showed the adherence of collectors on hemimorphite particles increased after de-sliming.
    Keywords: Flotation, Surface properties, Zinc-silicate minerals, Hemimorphite, Synergistic effect of mixed collectors
  • Ghasem Heydari, Javad Mehrabani *, Behnam Bagheri Pages 43-50
    In this research, the selective flotation of galena and sphalerite minerals was evaluated from a pyrite-rich lead-zinc sample. An optimum mixture of selective collectors against pyrite and also organic/inorganic pyrite depressants was obtained in the flotation of galena and sphalerite by an experimental mixture design. The effect of different collectors and pH values were investigated in the obtained optimum flotation condition. The results indicated that the mixture of Aero 404 Promoter collector with Potassium Ethyl xanthate (PEX) has the highest Pb recovery and separation efficiency. The mixture of auxiliary collectors of Aero 3477, Aerophine 3418 and Florrea 2255 with Potassium Amyl Xanthate (PAX) improved Zn recovery in comparison with the test in which PAX was added alone in the Zn rougher flotation stage. The highest Zn separation efficiency was achieved by Aerophine 3418 when it was mixed with PAX for which the lowest pyrite particles were floated. Zn separation efficiency was markedly improved from 47.47% to 65.31% from pH 9 to 12. It can be concluded that increasing pH with lime, up to 12, successfully depressed pyrite without any significant negative effect on Zn recovery.
    Keywords: Flotation, Pyrite, Mixture design, Auxiliary Collector
  • Vahid Radmehr, Ziaedine Shafaei *, Mohammad Noaparast, Hadi Abdollahia Pages 51-61
    The present research reviews two basic approaches for the separation circuit configuration analysis. The first approach is to optimize the circuit configuration. In this method, after a circuit modeling, a variety of search algorithms and mathematical optimization methods are used. Previous works show that this approach has more application in the flotation process. The second approach called the circuit analysis, evaluates the circuit configuration by considering a transfer function for each separation unit. This method provides great freedom for conducting a variety of investigations on the separation circuits.
    Keywords: Circuit configuration, Circuit analysis, Optimization techniques
  • Slavko Torbica, Veljko Lap?evi? * Pages 63-67
    Deformation modulus of rock mass has a significant role in the support design of an underground excavation. It is determined by expensive in-situ tests or by empirical models. Existing models for estimation of deformation modulus do not consider its stress dependence. Herein, data from several sources is used to develop a stress- (depth-) dependent relation for estimation of deformation modulus. The derived exponential expression incorporates the GSI, Youngs modulus and depth as input parameters for deformation modulus estimate. It is explained that at certain depth, the shear strength of rock joints will become close to the shear strength of a monolithic rock, and below this depth, the rock mass behavior is close to that of a monolithic rock, as well as the deformation modulus.
    Keywords: Deformation modulus, Young’s modulus, Rock mass, Stress
  • Soheil Mohajerani, Seyed Mohammad Esmaeil Jalali *, Seyed Rahman Torabi Pages 67-78
    Nowadays, numerical modelings play a key role in analyzing hydraulic problems in fractured rock media. The discrete fracture network model is one of the most used numerical models to simulate the geometrical structure of a rock-mass. In such media, discontinuities are considered as discrete paths for fluid flow through the rock-mass while its matrix is assumed impermeable. There are two main parameters to simulate the geometry of discontinuities in this model; the density and connectivity pattern of fractures. Despite the advantages of the discrete fracture network modeling, in order to apply the numerical solution schemes, the discretization of this model has encountered serious challenges due to the geometrical complexities. Generally, some of previous meshing methods present a framework that changes the geometrical structure and connectivity pattern of the model, and some others are incapable to mesh intricate networks with a large number of fractures. In this research, a new algorithm is developed to mesh the geometrical framework of three-dimensional discrete fracture networks. This algorithm is designed based on a refined conforming Delaunay triangulation and is computationally efficient, fast and low-cost. Furthermore, it never changes the geometrical structure of a DFN primitive model, therefore, the connectivity pattern will remain intact and the mesh is a proper representative of DFN. The algorithm was validated using the analytical methods and a series of sensitivity analysis was performed to evaluate the effect of meshing parameters on fluid flow using a finite element scheme of steady state Darcy flow. The results show that an optimized minimum internal angle of meshing elements should be predetermined to guarantee termination of the algorithm.
    Keywords: Meshing, Conforming mesh, DFN, Delaunay, FEM
  • Gholamabbas Parsapour *, Farhad Molhem, Hamidreza Montazari, Ehsan Arghavani, Gholamreza Biniaz, Samad Banisi Pages 79-82
    Water plays a key role in mineral processing plants. In order to process one ton of ore, 2.5 ton water is needed. Thickeners are commonly used for dewatering and recovering the water in most mineral processing plants. The underflow pulp density is increased by the sedimentation of particles and a clear water is then recovered from the overflow. One of the issues related to using the process water (thickener overflow) is the presence of suspended fine particles which create blockage in transfer pipes. The froth formed on top of thickeners is the main cause of this problem. In this study, a method is introduced and implemented to decrease the froth formed on the Sarcheshmeh Cu-Mo thickener surface. First, the old punched plate feedwell was removed and replaced by a vane type feedwell. A spray water ring was then installed using fish-tail type nozzles to break the froth layers by water. These modifications led to 63% relative reduction in the water turbidity, 11% relative increase in the underflow solids concentration, 20% relative reduction in torque, 19% relative reduction in its standard deviation and an increase of 6% in the water recovery.
    Keywords: density, Fish-tail nozzle, Thickener, Torque, Vane Feedwell
  • Elham Bakhshi, Vamegh Rasouli, Ahmad Ghorbani *, Mohammad Fatehi Marji Pages 83-89
    The hydraulic fracturing propagation is strongly influenced by the existence of natural fractures. This is a very important factor in hydraulic fracturing operations in unconventional reservoirs. Various studies have been done to consider the effect of different parameters such as stress anisotropy, toughness, angle of approach and fluid properties on interaction mechanisms including crossing, arresting and opening. Analytical solutions can only be used for simple fracture geometries and are not usually able to provide good predictions due to many simplified assumptions. Laboratory tests are also conducted under certain constraints like sample size and conditions that are different from the real field conditions. Numerical simulations, including continuum and dis-continuum based models have been used extensively to simulate hydraulic fracture propagation and its interaction with natural interfaces. However, calibration of simulated models with real field data is necessary to ensure the accuracy of the results. A calibrated numerical simulation can be used to model complex geometries. In this study, a Lattice numerical simulator, which is the advanced version of Particle flow Code (PFC) based on the granular particle physics, was used for numerical simulation of lab scale hydraulic fracturing. The scaling laws were also used to increase the dimensions of the simulated samples to allow increasing the rate of fluid injection and reducing its viscosity, hence reduce the simulation time. The interaction of hydraulic fractures and orthogonal fractures with angles of approach of 90°, 60° as well as non-orthogonal fracture planes with different filling materials ranging from strong to very weak were studied. The results showed good agreement with lab observations. In general the larger the angle of approach and stronger the filling material, the higher the likelihood of the crossing mode. Also, networks of regular natural fractures with two fracture sets were simulated. The results showed that the combination of different parameters define the preferred fracture propagation (PFP) which is not easy to predict using analytical solutions. In this situation and more complex real field cases, the use of numerical simulations are necessary to predict the propagation of hydraulic fracture and interaction modes.
    Keywords: Numerical Simulations, Lattice, Hydraulic Fracture, Orthogonal Fractures, Non- Orthogonal Interfaces
  • Aref Alipour *, Ali Asghar Khodayari, Ahmad Jafari Pages 91-97
    One of the main tasks to analyze and design a mining system is predicting the behavior exhibited by prices in the future. In this paper, the applications of different prediction methods are evaluated in econometrics and financial management fields, such as ARIMA, TGARCH, and stochastic differential equations, for the time-series of monthly copper prices. Moreover, the performance of these methods is investigated in predicting the time-series of monthly prices of copper during early 1987 till late 2014. This study shows that the mean of about thousand runs using the Stochastic Differential Equations (SDE) method for 33 out of range cases gives better forecasting results for copper price time-series in comparison to traditional linear or non-linear functional forms (such as ARIMA and TGARCH) to model the price movement.
    Keywords: Copper, price forecasting, ARIMA, TGARCH, stochastic differential equations