فصلنامه مهندسی معدن
پیاپی 4 (زمستان 1386)

Mineral sector as the essential part of the economy has important role for supplying industrie's raw materials. Investment promotion in this sector can earn high value added to the most industries. Consequently, it is necessary to recognize high priority minerals for future investment. In this paper, TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) method, one of the major techniques of multiple attribute decision making process, utilized for ranking the 33 minerals for future investment. For this purpose, based on the interviews with mining experties, 29 criteria are defined. Then their quantities and weights are calculated. After that, based on the weights obtaining from the interviews as well as applying equal weights, the rank of each mineral is determined. The results show that copper, coal, iron, gold, chromites, lead and zinc have high priority respectively for future investments in Iran.

Cost estimation is a fundamental task of engineering and business decisions and also plays an important role in mining projects. Cost estimation process is frequently employed during the prefeasibility and feasibility studies, which is complicated and time consuming. Several methods have been proposed which their application is related to the type of projects and conditions of the host country. In this study a software for estimating of the capital and operating costs of mining equipments has been developed. In this approach by comparison of the existing methods, a cost estimation model was established. Further, on the bases of the model a software along with its database was developed. This database was prepared by some data that published in a Western mining engineering institute cost estimator guide. The software was applied for Sungun copper mine. Results show that the software was adapted with the Iran conditions with a good accuracy. This software also can be used as a useful tool for equipment selection.

Solvent extraction was applied for the purification of a solution obtained from acid leaching of Mehdiabad oxidized zinc ore. The zinc PLS contained manganese and iron ions. D2EHPA was selected as a suitable organic extractant. At the begining, the effect of pH of aqueous phase and D2EHPA concentration in krosene were studied. Then the necessary numbers of stages were obtained by Mccabe Thiele diagram. D2EHPA at low pH (2.5) and 30% concentration was able to extract 87% of zinc from aqueous phase by 3 stages in the presence of Mn ions. At the end of process stripping experiment was performed by fresh sulfuric acid solution. At this stage, about 95% Zn ion was transferred from organic phase to aqueous phase.

The transport of hazardous waste from mining disposal site to groundwater and surface water is one of the most environmental problems. In this research after the characterization of the sample of toxic heavy metals i.e. Zn, Cd, Pb from cobalt in zinc leaching plant of Zanjan, compression and lime neutralization techniques were used for reduction of solubility of heavy metals using column leaching tests. For the compression three levels of 31, 35 and 40 centimeters and for the neutralization three levels of lime addition 0, 1, 2 centimeters were selected in column test. The best conditions were obtained with compression of 31 cm and thickness of 2 cm lime for the lowest solubility of toxic metals to environment.

In this article First geotechnical parameters of host rock of the south part of Isfahan subway net are studied then the main goal of instrumentation is described and installed instruments are introduced and some of results are presented. Different methods of back analysis and the way of optimizing these methods and the advantages and disadvantages regarding to are described as well. In continue three dimensional modeling which is used in this study is discussed. Back analysis is implemented to determine deformation modulus, cohesion and internal friction of the host rock. Utilizing the numerical modeling and applying least square method deformation modulus, cohesion and internal friction angle of the host rock are obtained 30 degrees, 150 KPa and 1.5 GPA respectively. Utilizing the optimization procedures and applying weighted least square and minimizing the maximum error, deformation modulus, cohesion and internal friction angle of the host rock are obtained 35 degrees, 300 KPa and 1.5 GPa respectively. These results show the least sensitivity to internal friction angle and the most to deformation modulus and Cohesion. The low sensitivity to internal friction angle may be due to the low overburden.

Trezaghi defined the first scientific definition for squeezing phenomenon in rocks. According to this definition, squeezing rocks are slowly deformed inside it tunnel by applied stressed without a perceptible change in their volumes. Also, Barla and International Society of Rock Mechanics (ISRM) define squeezing as a result of increasing share stress which cause convergence of tunnel. In this research the squeezing phenomenon of rocks in tunnel are reviewed. In the literatures, different methods including empirical, smi-emperical and theoretical-analytical methods are presented. For example, Singh, Goel, Jethwa and Hoek- Marinos are some of these methods. Imemzadeh Hasham tunnel which is under construction was chosen as a case study and squeezing phenomenon for this tunnel was studied. This tunnel is located in Tehran-Amol connecting road (Haraz road) with 12m width and 9m height. In this project, due to underground water condition, presence of discontinuities and faults in sandstone and shale of different formations, several collapses have been occurred. In this research work, geological conditions, geotechnical properties of rock mass and potential of squeezing and its intensity were studied. Results show that shale of Shemshak formation is in squeezing condition and failure is occurred frequently. Apart from the shale marl with interlayer of limestone and thick limestone of Mobarak formation have also potential of squeezing. As a comparison, it can be said that jethwa method is the best method in studying squeezing phenomenon in rock tunnel excavation.

Nowadays statistic approaches are widely used for rock slope stability, because they are simple and quick. The most famous of these methods for stability analysis of fractured rock masses is the key-block method (KBM). An extension to KBM, called key-group method (KGM) considers not only individual key-blocks but also groups of collapsible blocks into an iterative and progressive analysis. In iterations some of the groups can be extended and included a great part on the rock slope. One of the most important problems in this approach is to define the critical surface (critical key-group). In this paper we present an approach for finding the critical group which can be called directional key-group method, Because grouping of blocks progresses in the direction of slide surfaces of groups. This was carried out using the Mathematica high-level programming language. Finally it was shown that the proposed method yields more realistic results than the basic key-block method and a comparison with results obtained using a distinct element method (UDEC), demonstrated the ability of this method.