فهرست مطالب

Mining & Geo-Engineering - Volume:50 Issue: 1, Winter and Spring 2016

International Journal of Mining & Geo-Engineering
Volume:50 Issue: 1, Winter and Spring 2016

  • تاریخ انتشار: 1395/03/30
  • تعداد عناوین: 6
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  • Hamid Hedayati Sarab, Shahrak, Mohammad Noaparast, Sied Ziaedin Shafaei Tonkaboni, Sied Mehdi Hosseini Pages 1-12
    In the present study, the possibility of concentrating tungsten-copper vein ore in South Chah-Palang was examined using gravity separators including Jig Machine (-2360 μm), shaking table (-600흭 μm), and multi-gravity separator (MGS) (-120 μm). The representative sample contains 1.5% WO3 and 5.95% CuO. The main tungsten minerals were ferberite and wolframite and their appropriate liberation degree was approximately in the range of 250 μm. Box-Behenken and CCD response surface methods were applied to model and optimize jig machine and MGS results, respectively. Shaking table performance was modeled by full factorial design method. In Jig machine tests, the effects of water flow rate, frequency and feed particle size were investigated. Deck inclination, wash water, and feed water flow rate were operational parameters in shaking table. In the MGS testes, the effects of two parameters of tilt angle and wash water flow rate were inspected. In this set of experiments, WO3 recovery and grade were considered as responses of each model. The maximum recovery of WO3 in jig machine was obtained in water flow rate of 3.71 lit/min, frequency of 153rpm, and the particle size range of -2360ힽ μm. In this case, the grade and recovery of WO3 were 2.85% and 94.33%, respectively. The maximum WO3 recovery was 93.9% with grade of 8.20 % using shaking table in the deck inclination of 11 degree, feed water flow rate of 7 lit/min, and wash water flow rate of 8 lit/min. The maximum WO3 recovery in MGS attained with 3.45 degrees tilt angle and wash water rate of 3.16 lit/min. The grade and recovery of WO3 in the MGS method were 4.2% and 90.61%, respectively.
    Keywords: gravity separation, Jig Machine, MGS, shaking table, tungsten ore
  • Behzad Tokhmechi, Seyed Fazlolah Saghravani, Parham Janfeshan Araghi, Hosein Marvi, Mohammad Esmaeel Borhani, Abolfazl Darbani Pages 13-22
    The quality of concrete is highly dependent on the characteristics of its aggregate, such as the size, minerals, and their chemical properties. Even a small amount of impurities, such as hydrated sulfates, chlorine (salt), and acidic pH of the rock material, can adversely affect the quality of the concrete. Thus, many national codes and standards are developed for testing, selecting, and employing the rock materials in concrete. For instance, Iranian standards 446, 449, 1702, 4978, 4984, 7174, and 86721 are currently serving this purpose. In the present research, a new real-time system was developed in order to replace the customary chemical analysis and size distribution tests. 20 samples were taken from two mines, selected by the Building Material Committee of Semnan Province, in order to determine the dissolved chlorine and sulfate, pH, density as well as size distribution. The new system is constituted of hydraulic jacks and a reservoir, designed to take samples from the conveyer in given time intervals. The samples were washed with distilled water and real-time analyses of dissolved chlorine and pH were performed. The results showed 85% agreement with the results from laboratory analyses. The correct classification rate (CCR) was 92% for 13 samples.
    Keywords: concrete mixture, dissolved chloride, pH, real, time analysis, rock material
  • Hassan Bakhshandeh Amnieh, Mohammad Saber Zamzam, M.R. Mozdianfard Pages 23-36
    Technological progress in tunneling has led to modern and efficient tunneling methods in vast underground spaces even under inappropriate geological conditions. Identification and access to appropriate and sufficient geological hazard data are key elements to successful construction of underground structures. Choice of the method, excavation machine, and prediction of suitable solutions to overcome undesirable conditions depend on geological studies and hazard analysis. Identifying and investigating the ground hazards in excavating urban tunnels by an EPB machine could augment the strategy for improving soil conditions during excavation operations. In this paper, challenges such as geological hazards, abrasion of the machine cutting tools, clogging around these tools and inside the chamber, diverse work front, severe water level fluctuations, existence of water, and fine-grained particles in the route were recognized in a study of Tehran subway line 7, for which solutions such as low speed boring, regular cutter head checks, application of soil improving agents, and appropriate grouting were presented and discussed. Due to the presence of fine particles in the route, foam employment was suggested as the optimum strategy where no filler is needed.
    Keywords: EPB, geological hazards, mechanized tunneling, Tehran subway line 7
  • Mirko Ahmadfaraj, Mirsaleh Mirmohammadi, Peyman Afzal Pages 37-48
    The aim of this study is determination and separation of alteration zones using Concentration-Area (C-A) fractal model based on remote sensing data which has been extracted from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images. The studied area is on the SW part of Saveh, 1:250,000 geological map, which is located in Urumieh-Dokhtar magmatic belt, Central Iran. The pixel values were computed by Principal Component Analysis (PCA) method used to determine phyllic, argillic, and propylitic alteration zones. The C-A fractal model is utilized for separation of different parts of alteration zones due to their intensity. The log-log C-A plots reveal multifractal nature for phyllic, argillic, and propylitic alteration zones. The obtained results based on fractal model show that the main trend of the alteration zones is in NW-SE direction. Compared to the geological map of the study area and copper mineralizations, the alteration zones have been detected properly and correlate with the mineral occurrences, intrusive rock, and faults.
    Keywords: ASTER, Concentration–Area (C, A) fractal model, hydrothermal alteration mapping, Principal Component Analysis (PCA), Saveh
  • Babak Ghane, Omid Asghari Pages 49-60
    Most of the geochemical datasets include missing data with different portions and this may cause a significant problem in geostatistical modeling or multivariate analysis of the data. Therefore, it is common to impute the missing data in most of geochemical studies. In this study, three approaches called half detection (HD), multiple imputation (MI), and the cosimulation based on Markov model 2 (MM2) are used to impute the censored data. According to the fact that the new datasets have to satisfy the original data underlying structure, the Multidimensional Scaling (MDS) approach has been used to explore the validity of different imputation methods. Log-ratio transformation (alr transformation) was performed to open the closed compositional data prior to applying the MDS method. Experiments showed that, based on the MDS approach, the MI and the MM2 could not satisfy the original underlying structure of the dataset as well as the HD approach. This is because these two mentioned approaches have produced values higher than the detection limit of the variables.
    Keywords: censored data, collocated cosimulation Markov model 2, half detection, imputation, multidimensional scaling, multiple imputation
  • Seied Mohammad Raoof Hoseini, Ataalah Bahrami, Mostafa Hosseinzadeh Pages 61-76
    A sample from the small-sized tailing pile of an Iranian mica processing plant was subjected to a series of mica recovery experiments. Mineralogical and microscopic investigations indicated that the dominant mica mineral was phlogopite which was accompanied by plagioclase feldspars. Before beneficiation studies, the particle size distribution of the representative sample was obtained, and the specifications of each size fraction were investigated in detail. It was observed that the largest portion of mica (31%) is accumulated in the size range of 0.3 to 2.0 mm. Afterward, gravity concentration and flotation experiments were carried out. Results proved that shaking table could produce a mica concentrate with grade of 74%. Also, according to the flotation tests, it seemed the best size fraction was -150, and after that, -100힝. Flotation in combination with attrition scrubbing produced a concentrate with 92% mica content and 70% recovery. Finally, with respect to the results of all implemented experiments, a processing flow sheet was proposed for mica reclamation from the mentioned waste disposal.
    Keywords: flotation, gravity separators, mica flakes, reclamation, tailing disposal