Shahrood University of TechnologyJournal of Mining and Environment2251-85922220120909Investigation of blind massive sulphide deposit signatures in the calcrete layers as a geochemical barrier: A case study of Areachap, Kantienpan and Copperton deposits861016210.22044/jme.2012.62ENRezaGhavami-RiabiAssistant Prof. of Exploration Geochemistry, Faculty of Mining, Petroleum and Geophysics, Shahrood University of TechnologyH.F.JTheartSRK Consulting Engineers and Scientists, 265 Oxford Road, Ilovo, Johannesburg, South AfricaJournal Article20110908The trace element contents on the surface originated from mineralization would depend to the thickness of the calcrete layer above the ore deposit on the surface. A very thick layer of calcrete may not allow for much dispersion of the elements of interest in the surface. These elements may be concentrated in non-magnetic and magnetic part of calcrete. Based on the current research, mineralogical composition of the non-magnetic part of the calcrete consists of calcite, quartz and microcline and the magnetic part comprises of magnetite, hematite, calcite and albite (at Kantienpan). It could be demonstrated that calcrete samples close to the ore zone have higher contents of Cu, Zn and CaCO3 when compared to the calcrete samples further away from the ore zone. Lithogeochemical exploration program based on the visually cleaned calcrete samples may lead to the successful identification of underlying mineralization, but the dispersion of the interest elements may be severely restricted. It is however evident that these elements are available at the calcrete-sand interface and could then be dispersed by ground and rain water as in the case of mobile metal ions.Shahrood University of TechnologyJournal of Mining and Environment2251-85922220110401On the reduction of the ordinary kriging smoothing effect10211753810.22044/jme.2011.538ENH.RezaeeSchool of Mining, University of Tehran, TehranO.AsghariSchool of Mining, University of Tehran, Tehran0000-0002-3587-0220J.K.YamamotoDepartment of Environmental and Sedimentary Geology, Institute of Geosciences, University of São Paulo, São Paulo, BrazilJournal Article20111116A simple but novel and applicable approach is proposed to solve the problem of smoothing effect of ordinary kriging estimate which is widely used in mining and earth sciences. It is based on transformation equation in which Z scores are derived from ordinary kriging estimates and then rescaled by the standard deviation of sample data and the sample mean is added to the result. It bears the great potential to reproduce the histogram and semivariogram of the primary data. Actually, raw data are transformed into normal scores in order to avoid asymmetry of ordinary kriging estimates. Thus ordinary kriging estimates are rescaled using the transformation equation and after that back-transformed into the original scale of measurement. For testing the proposed procedure stratified random samples have been drawn from an exhaustive data set. Corrected ordinary kriging estimates follow the semivariogram model and back-transformed values reproduce the sample histogram, while keeping local accuracy.Shahrood University of TechnologyJournal of Mining and Environment2251-85922220120909A new algorithm for optimum open pit design: Floating cone method III1181256310.22044/jme.2012.63ENEbrahimElahimember of technical office, eastern Alborz coal companyRezaKakaieprofessor of Faculty of Mining Engineering & Geophysics, Shahrood University of Technology, ShahroodAmirYusefimember of technicaloffice, eastern Alborz coal companyJournal Article20111004Ultimate limits of an open pit, which define its size and shape at the end of the mine’s life, is the pit with the highest profit value. A number of algorithms such as floating or moving cone method, floating cone method II and the corrected forms of this method, the Korobov algorithm and the corrected form of this method, dynamic programming and the Lerchs and Grossmann algorithm based on graph theory have been developed to find out the optimum final pit limits. Each of these methods has special advantages and disadvantages. Among these methods, the floating cone method is the simplest and fastest technique to determine optimum ultimate pit limits to which variable slope angle can be easily applied. In contrast, this method fails to find out optimum final pit limits for all the cases. Therefore, other techniques such as floating cone method II and the corrected forms of this method have been developed to overcome this shortcoming. Nevertheless, these methods are not always able to yield the true optimum pit. To overcome this problem, in this paper a new algorithm called floating cone method III has been introduced to determine optimum ultimate pit limits. The results show that this method is able to produce good outcome.Shahrood University of TechnologyJournal of Mining and Environment2251-85922220110401Limestone chemical components estimation using image processing and pattern recognition techniques12613553910.22044/jme.2011.539ENF.KhorramM.Sc student, Mineral Exploration Engineering, School of Mining, College of Engineering, University of TehranH.MemarianProfessor of Geo-Engineering, School of Mining, College of Engineering, University of TehranB.TokhmechiAssistant professor of Mining Engineering, Faculty of Mining, Petroleum and Geophysics, Shahrood University of Technology0000-0003-1516-0624H.Soltanian-zadehProfessor of Electrical Engineering, School of Electrical and Computer, College of Engineering, University of TehranJournal Article20110920In this study based on image analysis, an ore grade estimation model was developed. The study was performed at a limestone mine in central Iran. The samples were collected from different parts of the mine and crushed in size from 2.58 cm down to 15 cm. The images of the samples were taken in appropriate environment and processed. A total of 76 features were extracted from the identified rock samples in all images. Neural network used as an intelligent tool for ore grade estimation and the features of every image were combined with weighted average method. In order to feature dimensional decrease, principal component analysis method was used. Six principal components, which were extracted from the feature vectors, captured 90.661% of the total feature variance. Components were used as the input to neural network and four grade attributes of limestone (CaCO3, Al2O3, Fe2O3 and MgCO3) were used as the output. The root of mean squared error between the observed values and the model estimated values for the test data set are 6.378, 4.847, 0.1513 and 0.0284, the R2 values are 0.7852, 0.8663, 0.7591and 0.8094 for the mentioned chemical composition respectively. The magnitude of R2 indicates the correlation between actual and estimated data. Therefore, it can be inferred that the model can successfully estimate the limestone chemical compositions percentage.Shahrood University of TechnologyJournal of Mining and Environment2251-85922220120910Relationship between fracture dip angle, aperture and fluid flow in the fractured rock masses1361456510.22044/jme.2012.65ENMohammadFatehiArashPashapourMaster Student, Faculty of Mining and Metallurgy, Yazd University, Yazd, IranJavadGholamnejadAssoc. Prof., Faculty of Mining and Metallurgy, Yazd University, Yazd, IranJournal Article20120125Most of the Earth's crust contains fluids, and fractures are common throughout the upper part. They exist at a wide range of scales from micro-fractures within grains to major faults and shear zones that traverse the crust. In this paper, the stress-dependent permeability in fractured rock masses have been investigated considering the effects of nonlinear normal deformation and shear dilation of fractures using a two-dimensional distinct element method program, UDE. A new analytical and numerical model was proposed to determine the relationship between fracture dip angle, aperture and permeability. The numerical work were conducted in two ways: (1) increasing the overall stresses with a ﬁxed ratio of horizontal to vertical stresses components; and (2) increasing the differential stresses (i.e., the difference between the horizontal and vertical stresses) while keeping the magnitude of vertical stress constant. The results showed that at the stress ratio of 1 the signiﬁcant shear dilation occurs at an approximately low stress and mean fracture angles. For the differential stresses case, the shearing process can result in breakage of the asperities, resulting in the decrease of the dilation rate and strain softening of the fracture.