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This paper was assesses the cavability of roof strata in mechanized longwall coal mining in terms of their principle parameters. For this purpose, the fuzzy decision-making trial and evaluation laboratory (DEMATEL) method was employed to study and analysis the influencing parameters and interrelationships among them. Since this method is based on the survey of experts to indicate the influences and involves uncertainty, therefore, the fuzzy coding was used. Given that the behavior of roof strata in the caving process is controlled by many factors, seventeen effective parameters in five categories were recognized. As a result of analysis, the parameters with the highest exerted and received influence were introduced. Besides, the impact and relation of factors in the cavability system were determined. After that, an approach was proposed for weighting the parameters in the fuzzy DEMATEL framework and then the importance of significant parameters were assessed. The conducted method provides a systematic approach for holistic analysis the principles parameters affecting the cavability of immediate roof strata in mechanized longwall coal mining and hence, is worthwhile for studying this complex and dynamic problem under uncertainty. [ABSTRACT FROM AUTHOR]

Mining methods such as block caving or sublevel caving rely on the characteristics of the rock mass to cave efficiently to fulfill an economical production. The identification of influencing parameters and cavability assessment are, thus, a prime geotechnical focus for all potential caving projects. In the caving operation, many factors, such as natural and induced factors, affect the caving performance. In this study, after discussing the caving process and identifying all effective parameters, the interaction matrix based on the rock engineering system (RES) is introduced to study the influencing parameters in rock mass cavability. The interaction matrix analyzes the interrelationship between the parameters affecting rock engineering activities. As the interaction matrix codes are not unique, probabilistic coding can be performed non-deterministically, allowing consideration of uncertainties in the RES analysis. As a result, the parameters with the highest probability of being dominant or subordinate, and also the parameters with the highest probability of being interactive, are introduced. The proposed approach could be a simple but efficient tool in the evaluation of the parameters affecting the cavability of rock mass in block caving mines and, hence, useful in decision-making under uncertainties. [ABSTRACT FROM AUTHOR]

In this article, the reliability of the cable system of a drum shearer machine was studied and analysed using operation and maintenance data from an Iranian mine for a period of two years. The tests for trend and serial correlation show that the times between successive failures for the cable system are not independent and identically distributed. A goodness-of-fit test shows that the power law process model provides a good fit to the failure data of this system. After parameter estimation for the power law model, reliability and failure rate plots were obtained. Based on analysis and results, a period of 125 h was defined as the reliability-based maintenance interval for the cable system of the shearer. The analysis shows that, by using this strategy, the reliability of the system will improve by at least 50%. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the use of image processing techniques in monitoring of bit wear, especially, WC/Co cemented carbide bits that are commonly used in rotary drilling in mining, civil and petroleum engineering. Image of the bits was acquired using a CCD camera. The background was subtracted from the image to reduce noise effects. A Laplacian filter has been used to enhance edge contrasts. Structural elements have been applied to dilate, erode and close boundary edges. Edge detecting was conducted using a canny edge detector. Image processing approaches; first order surface metrics, gray level co-occurrence matrix (GLCM) based texture analysis and minimum distance based classifiers have been used to estimate wear of tricone drill bits in rock drilling. A digital balance was used to obtain weight loss of the bits and also wear of their heel row and gage row (dimension loss) was measured using a micrometer in different directions. Results showed that, of the surface metrics, bit area and major length axis could be good measures for bit wear estimation. The entropy and contrast features of the GLCM method showed good correlations with bit weight loss. Of the minimum distance based classifiers just Euclidean, City block and Chebychev distances had reliable correlations with weight loss and heel row wear rather than other features. [Copyright &y& Elsevier]

Abstract: Principal Component Analysis (PCA) is used to determine the most effective parameters on the rock mass penetrability by considering their variance ratio in the first principal component. A model is developed for the prediction of rotary drills penetration rate using non-linear multiple regression analysis. Distribution functions for the effective parameters are calculated using measured data from two case studies. Applying the developed penetration rate model, a stochastic analysis is carried out using the Monte Carlo simulation. The proposed method provides a simple and effective assessment of the variability of the penetration rate model and its dependent parameters. Results showed that the PCA and Monte Carlo are suitable techniques for modeling and assessing the variability of rock mass penetrability parameters. According to the developed distribution model, with 90% of confidence level the penetration rate values range 0.2–2.5m/min, which shows the wide possible range of penetration rates for rotary drilling especially in sedimentary (limestone and sandstone bearing magnetite mineral of Golgohar mine) and Sarcheshmeh igneous porphyry rock masses. [Copyright &y& Elsevier]

Abstract: In this article, by using TOPSIS technique we propose a new method for mineral potential mapping that commonly used to exploration mineral deposits. TOPSIS is a practical and useful technique for ranking and selection of a number of externally determined alternatives through distance measures. We used TOPSIS and GIS to providing prospectivity maps for porphyry copper mineralization on the basis of criteria derived from geological, geochemical, and geophysical controls, and remote sensing data including alteration and faults in Ahar-Arasbaran area in North West Iran. This Method allowed a mixture of quantitative and qualitative information with group decision. The results demonstrate the acceptable outcomes for copper porphyry exploration. [Copyright &y& Elsevier]

Abstract: Underground mining method selection is one of the most crucial decisions that should be made by mining engineers. Choosing a suitable underground mining method to carry out extraction from a mineral deposit is very important in terms of the economics, safety and the productivity of mining operations. The aim of this study is developing a fuzzy model to selection the optimum mining method by using effective and major criteria and at the same time, taking subjective judgments of decision makers into consideration. Proposed approach is based on the combination of fuzzy analytic hierarchy process (FAHP) method with an advanced type of conventional AHP. FAHP is used in determining of the weights of the criteria by decision makers and then rankings of the methods are determined by AHP. The proposed method is applied for Jajarm Bauxite Mine in Iran and finally the most appropriate mining methods for this mine are ranked. [Copyright &y& Elsevier]