IRANIAN JOURNAL OF MINING ENGINEERING (IRJME)
Year:2009 | Volume:3 | Issue:6|Papers Count:15

One of the methods for investigating the mechanical properties of rocks is direct shear test. It is considered as the simplest and the most commonly used methods for the shear testing of rock specimens containing a weakness plane or a discontinuity. This kind of test is normally carried out in the laboratory, but it may also be performed in the field, using a portable shear box to test discontinuities contained in a piece of drill core. As the normal and shear stresses are applied by hand pumps in the portable shear tests, there are some doubts on the accuracy of results. These ambiguities may be eliminated when using electrical hydraulic pumps instead of mechanically controlled hand pump for applying shear stress on the specimen. The shear stress increasing rate would be regular and may be controlled and changed by means of electrical pumps. As the power supplier will be a 12 volts battery, the developed shear apparatus will also be portable. A series of shear tests have been conducted using both conventional and developed direct shear test apparatus. To be able to have a close comparison, artificially made specimens containing a discontinuity have been tested. The results obtained from these apparatus show some discrepancies which makes one think about the results of the conventional portable shear box.

Titanomagnetites are one of the most important resources for recovery of vanadium. Qara-aghaj hard rock titanium ore locating 36 Km far from Euromieh north-west of Iran, is one of these resources. Based on presented flow sheet for production of limonite concentrate, a by-product as magnetite concentrate containing 0.84% V2O5 is produced. Mineralogical studies performed by XRD, XRF, and SEM and analyzing by EDX indicated that Fe3+ has been partially replaced by V3+ in magnetite lattices. Extraction of vanadium from magnetite concentrate consisting of salt roasting, leaching and precipitation was investigated. The effective parameters on roasting such as percentage of sodium carbonate, concentrate particle size, roasting temperature and roasting time were studied and the optimum amount of these parameters were determined as 16 wt%, d80= 75 mm 1100°C and 2 hours, respectively. The leaching parameters such as roasted magnetite particle size, temperature and time were also investigated and the optimum amount of them were obtained as d80= 105 mm 90°C and 1 hour, respectively.

During construction of underground openings, such as: tunnels, shafts and caverns stress concentrations increase near these openings and instability problem occur in these underground excavations. Tests on thick-walled hollow cylinders of rock are a relatively easy, economical and realistic means to better understand stability and the mechanisms associated to underground openings failure. The mode of rupture observed in the tests was a pair of radial rupture planes. These rupture planes correspond to a compacting failure mechanism, because, these planes are perpendicular to major principal stress (tangential stress). This kind of rupture usually occurs in very porous material.

Loading and transportation are often the most expensive process in an opencast mining operation. Gohar Zamin, being an important reserve with some 600 Million tons of iron ore, is now in the planning stage and an optimum loading and transportation system would add considerably to the economics of its operations.In this paper, two main methods have been introduced. The first method is the conventional shovel and trucks system, whilst the second one is using belt conveyors. The appropriate crushing method decided and the optimum location of the crushers has been determined in both cases. These two methods have then been subject to economic comparison, using real data from field studies in Gohar Zamin mine.The paper concludes that the method of using an in pit crusher and belt conveyors, being technically advantageous, is also more economical than the conventional method.

The calcium removal from Jajarm bauxite ore by acid leaching in order to bauxite enrichment was investigated in this research. The results of XRD, XRF, ICP and chemical studies indicated that Diaspore (AIO(OH) is the major mineral phase and Hematite (Fe2O3), Quartz (SiO2), Anatase (TiO2), Calcite (CaCO3) are minor phases in the sample ore. At first, calcinations experiments were carried out to optimize calcinations parameters. The experimental results suggested 900°C and 60 minutes as optimizing calcinations parameters; leaching tests with hydrochloric acid were performed subsequently and 90°C, 30 min, 3M acid concentration, solid liquid ratio of 1:6,300 rpm agitation speed and 150 - 500mm particle size as optimizing leaching parameters were obtained. Temperature and acid concentration showed strong effect on the calcium removal. In the optimum conditions removal of more than 95.45% of calcium content was achieved from basic mineral and the calcium content was decreased below 0.05% within the residue bauxite and made it desirable for refractory and abrasives industries.

Anisotropy, which is a most important characteristic of metamorphic rocks such as schistose and gneissic rock, which should be considered in engineering evaluation. Most metamorphic rocks have foliated structure and they show considerable anisotropy in mechanical behavior. Therefore correct design and stability analysis of manmade structures confined whit these rocks require enough knowledge about their anisotropic behavior. The purpose of this research, study of anisotropic shear strength parameters of Calc-schist sample that obtained from exploration geotechnical borehole number one tunnel of water conveyance system Kordestan Azad dam. Study area is located in Sanandaj- sirjan zone. To received objective of the present investigation is used from three generic experiments as petrography, physical and geotechnical properties for determine geotechnical properties, triaxial tests were conducted on the samples with various anisotropic angles (b =0, 30, 60, 90) under confining pressure of 2, 4, 6 MPa with using from their results, drown Mohr circles and obtained shear strength parameters. Also strength under confining condition of specimens is predicted with proposed an empirical strength criterion Ramamurthy et al (1988) and used from their results predicted shear strength parameters. Results of this experiments show that shear strength parameters are anisotropic and is related to direction load, also changing curve of predicted results with experiment result showed good overlap.

Grouting proceedings are one of the ways to decrease permeability and to increase the resistance and fixation of jointed rocks in construction area. One of the following issues in this operation is to estimate the penetrating radius and the amount of cement grout that has been introduced as the main parameters of grouting operation. The analytical and numerical methods have been used to estimate these parameters. In analytical method 5 models were presented. In numerical modeling the profile of rock block, bore and grouted cleft were designed by UDEC software and then grout features and final pressure of grouting were entered. To investigate the above models, as a case study, the geotechnical data and grouting information of Seymareh site dam were used.The results of numerical and analytical modeling were compared with the real corrode (recorded in site) and analyzed. The computations show that in analytical modeling, the first model (Janson) can provide a better and more suitable assessment from the amount of injected grout in comparison with other models. The results of numerical modeling have acceptable accordance with the results of analytical models. But totally, numerical modeling can provide better assessment in the amount of injected grout. However, numerical computations are time taking and not easy to do in field because of the lack of calculating facilities during the operation, so, the use of analytical models, due to some simplifications, seems to be more practical during the grouting operation.

In this paper feasibility of determination of ore grade using neural network and image processing techniques is presented. In practice grade of 100 iron ore samples, from Choghart iron ore mine, were determined. Photographs of samples powder were then used for image characteristics study like Red, Green and Blue colors (RGB) and their standard deviation and Haralick's textural properties including Energy, Entropy, Contrast and Homogeneity. Initially the neural network was trained with 70 photo samples and then tested by another 30 photo samples. In training step, three procedures were followed. At the first methods, Red, Green and Blue colors (RGB) were trained to the neural network. Second method involved training of the system by addition of standard deviation to the RGB color and at third method Red, Green and Blue colors and Haralick's textural characteristics (entropy, contrast, energy and homogeneity) were considered and trained to the neural network. The results show that the trained neural network by the above three methods could determine the grade of iron ore with the accuracy of 95.2, 96.9 and 97.72 percent, respectively.