فهرست مطالب

  • Volume:54 Issue: 1, 2020
  • تاریخ انتشار: 1399/01/16
  • تعداد عناوین: 12
|
  • Mohammad Karamoozian *, Maboud Asgari Mehrabadi Pages 1-13
    Sulfide lead resources are being depleted and the exploitation of carbonate lead deposits is now the main focus of lead mining. Cerussite, PbCO3, is majorly discarded to tailing damps because it is difficult to be processed by flotation in lead concentration units. This paper not only investigates the optimization of cerussite flotation, but it also proposes a model for predicting the recovery. Froth flotation was used for cerussite recovery from a previously existing tailing damp in the ChahGaz mine in Kerman Province, Iran. The response surface method was used for experimental design and optimization of Pb flotation in which a statistical experimental model was suggested to model flotation kinetics based on the effective parameters. The results showed that particle size, pH, solid content, Na2S dosage, collector dosage and collector type to be the most effective parameters. These parameters were applied for investigating flotation kinetics. A three-fraction (with seven-parameter) flotation model, with fast, medium and slow kinetics rate constants was obtained via 64 designed tests. The proposed model showed a good agreement with experimental data (R2 more than 0.8). Also optimum conditions of cerussite flotation were set at pH= 9, d80= 53 µm, solid content= 26%, Na2S= 4000 g/t and collector dosage = 1500g/t of PAX.
    Keywords: Cerussite, Flotation, kinetics, modeling, Tailing damp
  • Negar Salehi Alamdari, MohammadHossein Khosravi *, Hooshang Katebi Pages 15-25

    The design of retaining walls depends on the magnitude of active pressure exerted from the backfill. Therefore, estimating the scale of this pressure is a fundamental factor in the design. In this study, to assess the active earth pressure, a rigid retaining wall was built capable of translating and/or rotating with adjustable speed. Further, several physical tests were conducted on a laboratory scale under the influence of uniform surcharge. In order to evaluate the behavior of the soil and the failure wedge, circular flat pressure cells and particle image velocimetry method were used. The results indicated that in the translation and translation-rotational modes, the distribution of lateral active pressure along the wall height was non-linear while it was relatively linear under rotation around the base. By increasing the amount of surcharge, the effect of the arching phenomenon at the lower portion of the wall was more evident. This led to a negligible magnitude of pressure at the base of the wall. In addition, it was observed that during the active motion of the wall, the distinction between the stationary region and the failure zone was a function of the mode of wall motion.

    Keywords: Active earth pressure, rigid retaining wall, rotation mode, translation mode
  • Aref Sardari, Eskandar Keshavarz Alamdari *, Mohammad Noaparast, Ziaedine Shafaei Pages 27-32
    The effect of pellet chemical composition and burning temperature on pellets’ properties of the Gol-e-Gohar hematite recovery plant was investigated in this study. Green pellets of different sodium hydroxide ratio and hydrated lime were prepared as well. Then the pellets were burnt in a muffle kiln under different temperature conditions. The Design Expert software was employed to explore the optimized conditions and to model the effective parameters in the pelletizing process. The wet compressive strength of green pellets was determined to be 1.4-1.5 kilograms per pellet. The porosity of burnt pellets at different temperatures was determined between 16% to 38%. The firing process of green pellets provided discrimination between the outer layer and the central part of individual pellets. The model developed by the experiment design software showed that the temperature was the most effective parameter on increasing the compressive strength. While the burn temperature increased the cold compressive strength, it reduced the porosity of pellets. The cold compressive strength of burnt pellets was improved through increasing the temperature. However, a further increase in temperature led to a decrease in the cold compressive strength, because of hematite decomposition into secondary magnetite.
    Keywords: Experiment design, Burn Temperature, compressive strength, Pellet, SEM
  • Ahmad Aryafar *, Hamid Moeini, Vahid Khosravi Pages 33-38

    Identification of geochemical anomalies is a significant step during regional geochemical exploration. In this matter, new techniques have been developed based on deep learning networks. These simple-structure-networks act like our brains on processing the data by simulating deep layers of thinking. In this paper, a hybrid compositional-deep learning technique was applied to identify the anomalous zones in Dehsalm area which is located in 90 km of SW-Nehbandan, a town in South Khorasan province, Iran. The compositional robust factor analysis (CRFA) was applied as a tool to help select a meaningful subset as an input to Continuous Restricted Boltzmann Machine (CRBM). The dataset consists of 635 stream sediment geochemical samples analyzed for 21 elements. Using CRFA, the 3rd factor (i.e. Pb, Zn, Cu, Ag, Sb, Sr, Ba, Hg and W), indicating epithermal mineralization in the area, was considered as an input set to CRBM. The best-performed CRBM with 80 hidden units and stabilized parameters at 150 iterations was finalized and trained on all the geochemical samples of the study area. Average square contribution (ASC) and average square error (ASE) were determined as anomaly identifiers on the reconstructed error of the trained CRBM. A statistical threshold was applied on the values of the criteria (ASC & ASE) and the resulting outputs were mapped to delineate the anomalous samples. The maps indicated that ASC and ASE have the same performance in the multivariate geochemical anomaly recognition. The anomalies were spatially confirmed with the mineral indexes of Pb, Zn, Cu and Sb, as well as several active mines of Pb and Cu in the study area.

    Keywords: Geochemical exploration, compositional data, Robust factor analysis, CRBM, Dehsalm
  • Mehdi Najafi, Ramin Rafiee *, SeyedMohammadEsmaeil Jalali Pages 39-43

    In open-pit mine planning, the design of the most profitable ultimate pit limit is a prerequisite to developing a feasible mining sequence. Currently, the design of an ultimate pit is achieved through a computer program in most mining companies. The extraction of minerals in open mining methods needs a lot of capital investment, which may take several decades. Before the extraction, the pit limit, which influences the stripping ratio, damp locations, ore processing site and access routes, should be designed. So far, a large number of algorithms have been developed to optimize the pit limits. These algorithms are categorized into two groups: heuristic and rigorous. In this paper, a new approach is presented to optimize the pit limit based on Dijkstra’s algorithm which is based on mathematical relations. This algorithm was implemented on a 2D economic graph model and can find the true optimal solution. The results were compared with those from the dynamic programming (DP) algorithm. This algorithm showed to have less time complexity compared to the dynamic programming algorithm and to be easier to write dynamic computer programs.

    Keywords: Graph Theory, Open Pit, Dijkstra Algorithm, Optimization. Dynamic Programing
  • Saeed Mojeddifar *, Mohammad Mavadati Pages 45-50

    This work applies support vector machine (SVM) algorithms in two versions of singular and general SVM classifiers to map hydrothermal alteration zones in the northwestern part of the Kerman Cenozoic Magmatic Arc (KCMA). Three visible bands and six SWIR bands of ASTER images were applied as inputs for SVM classifiers. The develosped algorithms were able to classify ASTER images into hydrothermal alteration or non-hydrothermal alteration classes. In singular SVM, nine classifiers were able to vote individually for every pixel in the image. Then, they were combined through integration rules to present a final decision about every pixel. The general SVM classifier integrated nine ASTER bands at the signal level to produce the final decision. The classification error rate showed that the general Gaussian RBF kernel-based SVM classifier had higher accuracy for the classification of hydrothermal alteration zones. The SVM results were then compared with other classified images based on band ratio and SAM methods. The main problem associated with these methods was that vegetation covering was highlighted as alteration zones while the SVM algorithm could solve this issue. Also, the verification of results, based on field and laboratory investigations, showed the SVM method to produce a more accurate map of alteration than that obtained from the band ratio and SAM.

    Keywords: Hydrothermal alteration, ASTER, Support vector machine, Band ratio, Spectral angle mapper
  • Marzieh HosseiniNasab *, MohammadHasan Sadeghi Pages 51-57

    This study investigates factors affecting the Blaine number, including type, shape, and size distribution of the grains, d80 effect, and retention time of materials in the mill. Samples were taken from different locations in production lines of the Golgohar and Chadormalu plants in Iran. For iron minerals, Davis tube tests were performed in four stages to assess the functionality of the magnetic separator to ensure matching conditions between the plant and laboratory. The Blaine air permeability system was used to analyze the Blain number. Results indicated that the samples with the same d80 but different grain size distributions had different Blaine numbers. More specifically, increasing the percentage of grains finer than 45 microns resulted in higher Blaine numbers. Moreover, in the Golgohar Hematite and desulfurization plant, the grain size distribution was relatively fixed, and minor variations in the percentages of grains finer than 45 microns led to a change in the Blaine number, and this was consistent between different days. During the concentrate production processes, higher grades of iron concentrate and lower grades of non-iron minerals were associated with lower Blaine numbers, which could be explained by the removal of iron-free minerals finer than 45 microns, including clay. Moreover, a 1% reduction in the clay minerals led to a 400-unit reduction in the Blaine number. Several samples of hematite concentrate and clay minerals with the same grain size distribution were analyzed to investigate the influence of density and the shape of grains on the Blaine number of magnetite concentrate. Here, compared to magnetite and hematite with irregular shapes, plate-shaped clay minerals showed higher Blaine numbers. Moreover, when the feed of the magnetic separator was grinded, the reduction in the grain size increased the Blaine number. In the Chadormalu plant, a retention time of 4.5 minutes in the mill was associated with the highest Blaine number as well as the least recovery of phosphorous minerals.

    Keywords: Blaine number, specific surface, grain size distribution curve, Davis tube test
  • Azadeh Agah *, Nona Soleimanpourmoghadam Pages 59-64

    This paper reports an attempt to show how acid mine drainage (AMD), as well as other heavy metals, pollute the environment and how this problem can be resolved. AMD is considered to be the main source of environmental pollution in areas where mining operations are undertaking. Since AMD and the factors that control it are of prime importance regarding the environmental preservation activities, this study investigates the presence of heavy metal pollutants in AMD. To achieve this goal, we implemented the ANFIS method to predict the presence of heavy metals (Zn, Mn, Fe, and Cu), taking into account pH, as well as SO4 and Mg concentrations.  Having used the ANFIS method, the comparison of predicted concentration with calculated data resulted in correlation coefficients of 0.999, 0.999, 0.999, and 0.999 for Cu, Fe, Mn, and Zn, respectively. The employed procedure proved to be easy to use and cost-effective to foresee the presence of heavy metals in AMD.

    Keywords: ANFIS, Heavy metals, Acid mine drainages, Shur River, Sarcheshmeh copper mine
  • Mehdi Gharabaghi *, Mostafa Taghavi, Ziaedine Shafaei Pages 65-70
    In the present study, reverse leaching method by the combination of acetic and lactic acid was used for recovery of phosphate from carbonate phosphate ore which contained about 10% P2O5. In the dissolution experiments, leaching time, temperature, acid concentration, solid/liquid ratio and particle size distribution were selected as important parameters and their effects were evaluated. The results showed that optimization of the leaching condition increased the grade of P2O5 to 29% with recovery of 90%. The kinetic experiments (time-temperature) in optimal conditions revealed that activation energy for the leaching was about 24.27 kJ/mol which is an indication of diffusion control processes and the rate of reaction was achieved as ⦋1-2/3 α-(1-α)^(2/3) ⦌=k0e-24.27/RT.t. Results showed that by organic acid leaching, it is possible to produce phosphate concentrate from low grade calcareous phosphate ore. In the present study, the reverse leaching method with the combination of acetic and lactic acid was used for the recovery of phosphate from carbonate phosphate ore, which contained about 10% P2O5. In the experiments carried out on the dissolution, leaching time, temperature, acid concentration, solid/liquid ratio, and particle size distribution were selected as important parameters, and their effects were evaluated. The results showed that the optimization of the leaching condition increased the grade of P2O5 to 29% with a recovery of 90%. The kinetic experiments (time-temperature) in optimal conditions revealed that activation energy for the leaching process was about 24.27 kJ/mol which is an indication of diffusion control processes and the rate of reaction was achieved 0e-24.27/RT.t. Results showed that the application of organic acid leaching would facilitate producing phosphate concentrate from low-grade calcareous phosphate ores.
    Keywords: Reverse leaching, Phosphate, dissolution, Leaching Kinetic, organic acid
  • Mohammad Hajiazizi *, Masoud Nasiri Pages 71-75
    Slope stability is one of the important issues in geotechnical engineering. In this regard, due to the growth in the number of numerical approaches, the two and Three-dimensional Finite Element Method (FEM) and the Finite Difference Method (FDM) are more important. In this paper, the effects of friction angle and cohesion on the safety factor of slopes were investigated, and the results of 2D & 3D FD were compared with those of FE analyses. The results of 600 analyses indicated that in cohesive soils (friction angle equal to zero) it was not necessary to analyze the slope in the 3D analysis, because the results of 2D & 3D were the same, with a difference of less than 0.3%. In granular slopes (cohesion equal to zero) the safety factor obtained in the 2D analyses (both FEM and FDM) were similar. However, the values in the 3D state were higher, and this indicated that in such a condition, unlike cohesive soils, the results of the 2D analysis were more conservative. It should be noted that in the 2D FDM for pure granular soils, the safety factor values for fine and medium mesh types were close. For the coarse mesh, however, the results were higher, and in pure cohesive slopes, in all three states (fine, medium, and coarse mesh tyes), the results were the same.
    Keywords: Friction Angle, Factor of safety, FEM, FDM, Slope
  • Farzad Sotoudeh *, Mohammad Ataei, Reza Khalookakaie Pages 77-85
    Determining the limit of underground mining and stope layout is one of the most important points in underground mining and production planning. Numerous algorithms have been offered to address the stope layout optimization problem both in two-dimensional and three-dimensional space based on economic value. In this paper, a new heuristic algorithm with different strategies was developed to generate optimal and sub-optimal underground stope layouts. In this algorithm, all possible stopes were created based on an entirely economic block model considering stope dimensions in the three-dimensional space. Afterward, the algorithm generated a family of non-overlapping stopes over all possible stopes and selected the highest economic value as the final solution.  Also, a user-friendly computer program named Stope Layout Optimizer (SLO3D) was designed in C# object-oriented program, and two separate examples were set for a better understanding of the algorithm. The application of the proposed computer program was implemented on a real copper deposit, considering three different strategies. The final output consisted of 29 stopes with a value of US$ 37 million. The results proved that the new heuristic algorithm was able to increase the final economic value by 49.04% compared to the floating stope method. Furthermore, the three proposed strategies were investigated for the same deposit. The results of this procedure illustrated that the probabilistic approach could generate higher economic values and sub-optimal values compared with the other two strategies discussed in previous studies regarding this issue.
    Keywords: Underground Mining, Production Planning, Stope Layout Optimizer, Optimization, Heuristic algorithm
  • Hadi FathipourAzar *, SeyedMohammadEsameil Jalali, SeyedRahman Torabi Pages 87-92

    This paper aims to study the mechanical behavior of rocks subjected to different mechanical loading conditions using the Cohesive Crack Model (CCM) and Grain-Based Model (GBM) in the Distinct Element Method (DEM) simulations. In the GBM-DEM, the Voronoi tessellation scheme is used, and intact materials are simulated as a collection of structural units (particles/blocks) bonded together at their contact areas. Implementing the CCM revealed a nonlinear behavior of grain interfaces under various loading modes. Numerical simulation of a tension-compression and direct shear test was conducted to verify that the CCM was implemented correctly. The simulated numerical curves were consistent to the results of theoretical calculations, indicating that the model incorporated into GBM-DEM could simulate more realistically similar to the micro-cracking mechanisms. Finally, CCM was used to simulate the uniaxial and biaxial compression tests under the Universal Distinct Element Code (UDEC). The results of the models were in a good agreement with the relevant responses of the rock under different loading conditions, verifying the applicability of the CCM.

    Keywords: Cohesive crack model, Grain based distinct element model, interface, Constitutive model, calibration