فصلنامه مهندسی معدن
پیاپی 18 (بهار 1392)

Existence of rock fracture is very important in evaluating the penetration rate (PR) of TBM in fractured rock masses. In previous research works, the influence of geometrical properties of a joint set such as joint spacing and orientation on PR has been investigated. Since the actual rock mass is geometrically complex, the hybrid Discrete Fracture Network- Distinct Element Method (DFN-DEM)which is used a closer conceptual modelto the reality (DFN) and facilitated a powerful numerical method (DEM) is used for numerical modeling of PR of TBM in fractured rocks. The DFN models is based on stochastic representation of fracture systems, using the probability density function (PDF) of fracture parameters (e.g. orientation, length) formulated according to field mapping results and generated by Monte Carlo method. Using a number of DFN-DEM models for predicting the penetration rate of TBM, a probabilistic numerical modeling is established. Numerical modeling results show that the PDF of positive incremental chipping area follows the normal distribution with the mean value of 46%. The Probabilistic Cumulative Distribution Function (PCDF) of results shows that the positive incremental chipping areas are greater than 20% and 33% when 95% and 80% are respectively considered.

With a view to estimate the heavy metals ratio in the surfacial soils of the Sarcheshmeh copper mine area and to evaluate the pollution level, 120 surfacial soil samples have been collected up to the depth of 30 centimeters and have been analyzed for the heavy metals of Pb, Ni, Se, Mo and Zn with the help of Inductively Coupled Plasma-Mass Spectrometer (ICP- MS). In the samples of the studied soil, the average of the recorded concentration of elements for lead, Nickel, Selenium, Molybdenum and zinc are 127, 27, 1, 7 and 252 (mg/kg) respectively. The order of the average frequency of the heavy metals concentration consist of Zn>Pb> Ni> Mo> Se. The comparison of the heavy metals concentration average and the toxic potential in the soil samples has shown that an average with respect to the world average of the uncontaminated soil amounts and shale. The average of Pb, Ni, Se, Mo and Zn elements shows a higher quantity with respect to the world average quantity. Ni element contains lesser average as compare to the shale average. The pollution factor for the study elements has been calculated on the basis of the soil background concentration and has been categorized on the basis of the uncontaminated world soil average with respect to the Hakenson classification. The calculation of the corrected pollutant degree shows the degree of the bulk intermediate pollutant (2.99-3.24) for the average soil sampling of the study area which is on the basis of the background quantity and the world average quantity of the uncontaminated soils. The provided conclusion from the calculation of the concentrated factor, for some of the samples show that the average of the lead, Zinc and Mo elements stations are more than the background values and the unnatural metal concentration are covered under the study area. Given conclusion from the calculation of Geoaccumulation index of the soil sampling can explain that the Nickel and Selenium elements are lying with uncontaminated area and the Zinc and Mo elements are lying with uncontaminated area and up to low contaminated area and lead element is lying with the area of low contamination.

In this paper, the beneficiation treatment of iron concentrate from the Mazreh copper mine mineral processing plant tail has been studied by a wet magnetic separation method based on a full factorial experiment design and the process analysis has been made using Partial Least Square (PLS) modeling. The obtained results indicated that the production of iron concentrate with an appropriate recovery and assay would not be easily obtained using only one step wet magnetic separation, but sufficiently removing of the unwanted sulfur and silica elements is impossible and needs at least two steps magnetic separation practice and further grinding. A detailed investigation indicated that by employing the two magnetic separation, iron concentrates with 3.7-4.5 % SiO2 and 67.2-69.3 % Fe with recoveries of 78-92% are attainable depending on operating variables. The sulfur amount was negligible and was reported below detectable range (less than 0.001%). The use of partial least square modeling yielded a three component model explaining 92.11% and predicting 73% of the total variance of the responses simultaneously. The PLS modeling results indicated that the grinding and subsequently primary and the secondary magnetic intensities, in turn, are the most influential factors on iron concentrate processing. The Sweet spot plot as an overlay of response contour plots indicated that there is a wide optimum region within searched space wherein appropriate iron concentrates are easily obtainable, which was verified by the experiments.

The technological development in manufacturing and installation of new optical sensors for hyperspectral image acquisition, which collect images in order of hundreds of spectral bands, have been used for remote sensing of the rocks and minerals in recent years. The aim of this study is to evaluate Hyperion hyperspectral data for mapping of hydrothermally altered areas and iron oxides bearing areas related to porphyry copper ore deposits. The study area is located in Urumiyeh-Dokhtar magmatic belt that hosts many important porphyry copper deposits such as Darrehzar and Sar Cheshmeh, which are located southwest of Kerman city. The spectra are extracted from images using pixel Purity Index method. These spectra were used for recognition of different hydrothermal alteration zones, using spectral angle mapper. The hydrothermal alteration and iron oxide minerals were mapped and validated through field checking.

In this study vanadium (V) was extracted from acidic solution using of two extractants, Alamin 336 (trioctylamine) and octylamine which coated on the surface of magnetic nanoparticles. Magnetic iron oxide nanoparticles were successfully synthesized by co-precipitation method. XRD analysis showed the magnetite phase with crystal size of 15 nm for synthesized nanoparticles. The surfaces of the particles were coated by alamin 336 and octylamine and then were used for vanadium separation from acidic solution. Vanadium (V) extractions from synthetic solution lead to remove of %88.89 and %96.29 of vanadium (V) by Alamin 336 coated and octylamine coated nanoparticles, respectively. Although these results were promising in this stage higher extraction by octylamine as a novel extractant was interesting. FT-IR analysis for prepared adsorbents showed that the amines were successfully coated on the nanoparticle’s surfaces. The bands centered around 3440 cm-1 and 1630 cm-1 were assigned to the O–H vibrations of adsorbed water on the surface of nanoparticles in both samples. The peak at 570 cm-1 corresponded to the Fe–O vibration of Fe3O4. Presence of C-H binds of alamin 336 was confirmed by peaks at wave numbers of 2924 and 2853 cm-1 and a weak peak in 2960 cm-1. A band in the region of 2930 cm-1 was ascribed to asymmetric stretching of the C–H2 groups. Two weak bands around 2930 cm-1 were attributed to symmetric stretching of C–H2 and asymmetric stretching of C–H3. A band at 1053 cm-1 assigned to C–N stretching vibrations. The results indicated that octylamine has been grafted onto the Fe3O4 nanoparticles. FT-IR analysis founding after extraction in acidic solution was different. Alamin 336 separated from nanoparticles and vanadium just adsorbed by nanoparticles but octylamine remained on the surface of nanoparticles

In This study, nano structure of LDH with molar ratio 2:1 and 3:1 was synthesized using process of coprecipitation of salt magnesium nitrate, Aluminium nitrate. In buffer medium of sodium carbonat and sodium hydroxide. The properties of structure and morphological of LDH were investigated using XRD, SEM and FTIR. The results show that some properties in LDH such as layered structure, surface Area is high and loading of anion and ion exchange, make it useful for adsorption of anionic pigments. In our study, adsorption kinetic and equilibirium of adsorption sulphate were mentioned. Results show that at this process, equilibirium time is 90min (amount of adsorption 30.22 gr/gr adsorbent), pH average and amount of adsorbent 0.5 gr. as well as later of conclusion with kinetic and isotherm models, pseudo first kinetic model and langmiur model is selected.

The fracture behavior of cracked rock masses under combined tension-shear loading is an important issue for mining engineers in order to extract more efficiently or to prevent destruction of mines. Therefore, in this paper, the combined tension-shear fracture behavior of Gorveh marble is investigated experimentally and theoretically using the center cracked circular disk (CCCD) specimens of various sizes. The experimental results show that the fracture resistance of Gorveh marble increases by increasing the size of samples. As a result, in order to predict the fracture load of rock masses, the size dependency of the fracture resistance should be considered. Therefore, a new criterion is proposed to investigate the size effects on tension-shear fracture behavior of rock materials. The new criterion is a modified form of maximum tangential stress (MTS) criterion in which the higher order terms of the elastic stress field are taken into account. Finally, the fracture behavior for rock masses of Gorveh marble is predicted using the new criterion.

Modeling of rock mass discontinuity systems is generally based on three principle geometrical, mechanical and probabilistic. In this paper, rock mass discontinuity systems are geometrically modeled. In geometrical modeling methods, discontinuities can be modeled as either finite persistence or infinite persistence. Due to the applied limitations of geometrical modeling of discontinuity systems as infinite persistence, this research considers the geometrical modeling of discontinuities as finite persistence. In modeling of discontinuities with finite persistence, the modeling process is very difficult, but on the other hand, this method is capable of modeling discontinuities that are geometrically more similar to the real discontinuities. Therefore, the modeling results would be more reliable. In this study, the blocks created by the intersections of discontinuities were determined in MATLAB software. Finally, based on Beacher's discontinuity disk model and using Lin algorithm, two dimensional modeling of discontinuities was obtained.

Major structural elements in Qaleh-Zari mine are faults, joins, veins and dikes that are located in 2 principles dextral shear zones. Trend of the main shear zone is N135 and it has recognized as the primary, Trend of another one that it's formed in secondary phases by continuation of dextral shear activity is N75. In order of abundance, main fractures are in NW-SE, NE-SW, ESE trends, that they are according to dominant fault's trend in the area, and they are orderly parallel with Riedel and anti-Riedel and extension fractures. The structural elements are in two phases, and follow from shear zone geometry. Simultaneous with increase of shear strain, primary phase has rotated dextrally and then second phase has formed, therefore type of deformation in the area is non-coaxial.