نشریه روش های تحلیلی و عددی مهندسی معدن
پیاپی 15 (بهار و تابستان 1397)

One of the most crucial decisions in mine design is to locate mine infrastructures. The problem of locating a processing plant can be considered in the form of a multi-objective case, which can be solved by goal programming method. In this paper, a fuzzy-based goal programming approach was developed in order to solve the problem of processing plant site determination. In order to determine the efficiency of the developed approach, Sungun copper area was studied. In this case, five goals were considered as adjacency to crusher, adjacency to tailing dam, adjacency to power source, distance from blasting sources, and topography of the available land. Furthermore, six feasible alternatives were initially specified by studying Sungun area map, and then were prioritized using the approach. After investigating the considered area, it was specified that the determined site is the most ideal alternative in this case, considering the levels of the goals and their fuzzy weights.

Due to environmental pollution caused by various contaminants through mining activities, over the years, many chemical and physical methods used to purge ecosystems which often associated with high costs. Hence, today the biological resources of the environment are used to clean up contaminated areas with a variety of pollutants. One of the most inexpensive methods for removing contaminants from wastewater, water and soil, is phytoremediation processes. Summary: Given that in the real world, environmental factors affect each other, to achieve real results, the interaction between these factors should be considered. In this study, the cognitive map method to evaluate the impact of the environment on phytoremediation efficiency factors with regard to relations between them have been used in a case study. The development of mining activities and non-compliance with environmental requirements, has caused the huge amounts of contaminants of mining industry such as wastewater of mine concentrator plants enter to the environment through water. On the other hand, in recent years, the use of biocompatible phytoremediation processes in purify the wastewater of mine concentrator plants have been significant results. Evaluate the efficiency of phytoremediation process and identify different effective environmental factors on it, not only reveal the wider dimension of the application of this new technology, but also help to the designers of this natural systems to implement it. Methodology and Approaches: In this study, the cognitive map to identify causal relationships between environmental factors affecting the efficiency of phytoremediation mineral wastewaters and how each factor affect the efficiency of phytoremediation is used. Also determine the most effective identified factors assuming enabled each of the factors identified in cognitive map and implementing hybrid learning algorithm will be obtained that represents the impact of environmental factors on the efficiency of inorganic wastewater phytoremediation process. Results and Conclusions: The results of the study wastewater phytoremediation Sungun copper mine concentrator plant shows that "the amount of heavy metals in the tailings dam," with the relative weight of 0/37, "the metal content of ore," the relative weight of 0/34 and "dissolved heavy metals in wastewater, "the relative weight of the criteria 0/33, have been the most important environmental factors and have great impact on the efficiency of phytoremediation process.

Spare parts management and logistics is an aspect of product support management which influences the product life cycle cost. The availability of spare parts upon demand decreases the product down-time and increases the utilization of the system/machine and consequently the profitability of the project. If the optimum number of spare parts is stored in the inventory, this minimizes the product life cycle cost as a goal function, and the optimum number is calculated taking different factors into account, such as the part criticality, the part purchasing cost, the distance between the manufacturer and user, and the lead time. Forecasting the required support/spare parts based on technical and operational characteristics of a system, is the one of the best ways for optimizing unplanned stoppages. This paper discusses about product support (required spare part) logistics based on product design characteristics (reliability). In first step, the reliability of component was analyzed and then required spare parts, the economic order quantity and reorder point with respect to annual demand rate was calculated. A case study of Sungun Copper Mine is used to demonstrate how the proposed approach can be applied.

In present research, theoretical and applied concepts of geometric probability have been studied ‎and the relationships of geometric probability have been presented to determine the probability of ‎intersection of various geometric shapes with diverse types of grids. In this regard mineral deposits ‎based on defining the shape ratio parameter as ratio of breadth to length of the deposit (‎ ‎) ‎were classified to 3 types of linear, circular and elliptical shape. The detection of mineral deposit is ‎possible under condition that the deposit is intersected at least once by the lines of exploration grid. ‎ Arrangement of accurate and optimum location of exploration works entitled designing of ‎exploration grid is one of the essential requirements in all stages of mineral deposits exploration. ‎Designing the optimum exploration grid is the most important as well as critical stage for ‎exploration of mineral deposits which is carried out on the basis of geological conditions and ‎characteristics of deposit and the amount and type of available exploratory information. The type, ‎shape, dimension of cells and orientation of the grid respect to the estimated direction of the ‎deposit, perform the geometry of exploration grid. Since the geometric parameters of mineral ‎deposits are stochastic, exploration of mineral deposits is also stochastic and always associated with ‎uncertainty and some risk. As a result from this view point the exploration problem is similar to the ‎geometric probability problems.‎ Methodology and Approaches: According to conventional exploration methods of mineral deposits by various exploration grids as ‎well as similarity of mineral deposits with the usual geometric shapes, designing the optimum ‎exploration grid for each type of deposit was presented based on existing relationships in geometric ‎probability. In this context as a case study, designing the optimum exploration grid for two copper ‎indices detected by remote sensing operation located in the south-west of Kerman, one with ‎approximately linear structure (with a shape ratio of 0.14) and the other one with approximately ‎circular shape, was carried out using the geometric probability.‎ Results and Conclusions: Due to the similarity of exploration of mineral deposits to geometric probability problems in this ‎research, existing relationships in geometric probabilities were used to determine the probability of ‎detection by the various exploration grids. By employing the mentioned approach, the size of ‎optimum exploration grid was calculated for each index considering minimum exploration ‎probability, 0.5 and favorite exploration probability, 0.95 for both randomly oriented and oriented ‎situations.‎

Simulations based on Multiple-point statistics (MPS) form a class of newly developed techniques that have received great attention in recent years and are mainly used to map spatial complexity and heterogeneity of geological phenomenon. One of the most commonly used pattern based multiple-point geostatistical simulation algorithm is called Filtersim. In the conventional Filtersim algorithm, the detected patterns in training images are transformed into filter score space using a fixed number of filters that are neither dependent on the training images nor on the characteristics of patterns extracted from them. Through using principal component analysis in current study, a set of new filters are designed in such a way to include most structural information specific to the governing training image resulting in the selection of closer patterns in the filter score space. Comparing the results of applying our proposed filters to that of conventional Filtersim algorithm shows a significant improvement in recovering expected shapes and structural continuity in the final simulated realizations.

MPS simulation is capable of reproducing complex geological patterns that cannot be modeled by two-point statistics moments such as variograms. One of the commonly used pattern-based approach, FILTERSIM, introduces filters to summarize high dimensional patterns into a filter score space. Then, it classifies the patterns into a limited number of classes. FILTERSIM uses six predefined filters, which are not specific to the Training Image. The aim of current research is to introduce new improvements to the initial FILTERSIM technique through defining new adaptive filters. Methodology and Approaches: In contrast to original FILTERSIM method, our approach uses some filters which are designed specifically for any given Training Image using PCA analysis. In addition, our approach uses a combination of raster path and random partitioning methods in the course of simulation. The raster path approach results in simulations showing a good continuity of the patterns. The random partitioning is a new feature that allows better simulated realizations as compared to the straightforward use of the raster path. Results and Conclusions: The newly proposed approach have been tested on some training images and the results have been compared with previous pattern-based algorithms. Through visual inspection and some discrepancy measures it is shown that the simulated realizations obtained by our approach are much closer to the training image than those obtained with the other methods. In particular, the continuity of the patterns is better preserved with the proposed method.

Summary: Simulation method give use most probable models that could be to obtain the best and worst case of a resource. So, average of these models is similar to estimated model but will not have estimated model problems. In the introduced new method after determining the rock type probability models the grade distribution is evaluated using geostatistical simulations. This method in addition to containing the probability models use from simulated grades that case be most authentic. Performance of method presented using a case study of a porphyry copper mine in Chile. Geological modeling is one of essential processes in ore reserves and resources evaluation that is precedence over the grade estimate. It is containing the deterministic division of deposit into smaller subdomains that called geological units. Although it cased to present the better treatment from the spatial grade variability, but it is not possible to present the uncertainty models in the boundaries of geological units that are need to classify the ore reserves and resources according to international standards such as JORC. This article presents an approach that uses geological uncertainty that could be incorporate in the evaluation of mineral resources. Introduced method applied on the rihoblanco deposit case study in chile. Methodology and Approaches: At first to obtain probabilistic descriptions of three different lithological units the geostatistical simulation have been used in this deposit (granodiorit, tourmaline breccia and another breccias). Then to determine the grade uncertainty of the deposit the conditional simulations have been applied. Finally, mineral resource model presented using weighting the copper grade realizations by occurrence probability of deferent geological units. Presented model able to produce a grade model that contain the geologic models uncertainty with avoidance of artificial models that caused by deterministic boundary hypotheses between high grade and low grade areas of ore in near the geologic boundaries. Results and Conclusions: Introduced method presented better results compared to the kriging method. Results shown that evaluation of the deposit geological uncertainty prevented from creates the unrealistic models of kriging method. Reliability of model is evaluated which less standard deviation of weighted realizations conditional variance show that reliability of them are suitable. Also, coefficient of variation in domains boundary was low which shows the method is suitable and uncertainty in boundaries is low. Also, presented new method compared with general simulation of grade distribution that new method represented higher tonnage percentage in grade-tonnage curves.

Deep excavations in urban areas require not only the stability of retained soil, but also special attentions due to the buildings existing nearby. They must be designed in such a way that the requirements for both ultimate and serviceability limit state for supporting system and neighbouring structures are satisfied. Anchored diaphragm walls are one of the safest lateral supports which help in overall stability of excavated areas. Diaphragm walls represent in general a considerably more complex problem than gravity or cantilever walls. Methodology and Approaches: The wall displacement, maximum bending moment and anchor extreme force were calculated using a dynamic PLAXIS finite element program. The soil was considered as elasto-plastic material, using Mohr–Coulomb constitutive model. The wall and the anchor were considered to behave elastically. Considering the dynamic applied load, absorbent boundaries were assumed to prevent dynamic wave reflection. Three different historical strong motions namely, Tabas, Bam and Roodbar were applied to the wall. The above mentioned outputs were obtained for different excavation geometry and mechanical properties for soil. Results and Conclusions: general results can be drawn as following:1-Change in the soil stiffness (modulus of elasticity and cohesion) from soft to stiff has caused the maximum wall displacement and bending moment increase by 76% and 20%, respectively.
2- Under dynamic load the maximum lateral displacement of the wall is at its top, while the static wall displacement is maximum at about one third the wall height measured from its toe.
3-Peak ground acceleration has direct effect on maximum wall displacement and bending moment, while earthquake frequency has inversely changes these output parameters. Based on obtained results 30% increase in earthquake acceleration has caused the maximum wall displacement increase by 15%
4- The maximum displacement and bending moments increased noticeably under earthquake load. So, for diaphragm walls in earthquake prone area, dynamic case should be considered in design. Albeit, building codes, accept higher displacement and bending moments under exceptional loading's.

Summary:
In this study, three different natural joint geometries in dimensions greater than 2500 cm2 were selected from the field. The geometric parameters of the surface joints have been calculated from the scale of 50 × 50 mm2 to 500 × 500 mm2 and the effect of scale on these parameters and their variations with scale has been discussed.

The scale dependency of discontinuity surface roughness and shear strength has been investigated by many other researchers over the last three decades. Many of these studies have produced conflicting results. Some studies have shown a decrease in strength and roughness with increasing discontinuity size. Other studies have shown the existence of positive scale effects, a combination of positive and negative scale effects, or no scale effect. The present study attempts to investigate the effect of scale on the geometrical properties of rock joints.

Methodology and Approaches:
In this study, three natural smooth, undulating and stepped rock joints were prepared and their surfaces were scanned by 3D optical scanner. The surfaces were digitized and the geometric parameters were calculated by the code written in Matlab software. The geometric parameters were calculated for the square widows that were centered at the same locations and were measured from 50 × 50 mm2 to 500 × 500 mm2.
Results and Conclusions: The results showed that the effect of scale on various geometric parameters are not the same and will have different results depending on the distribution of primary (waviness) and secondary (unevenness) roughness. The angular parameters of rock joint surfaces, in the scale of greater than 400 cm2, are independent of scale. However the amplitude parameters of rock joint surfaces, in the surfaces with dominant waviness, increase with increasing of scale (at least up to 2500 cm2)

Summary: During or after underground drilling such as oil well drilling, instabilities are observed in wells, in such a way that 90% of these instabilities are related to Shale formations. On the other hand, Shale formations are found in 75% of all drillings in Iran, causing various difficulties such as complete or partial collapse of wells before reaching the reservoirs. Shale porosity may vary from small (a few %) to quite high (up to 70%). Even with highest porosities, permeability remains very small. In this study, by considering geophysical log data and using experimental relations (presented by researchers) in Shale rock, physical and mechanical properties of Shale layer in Asmari formations are calculated and after that by using finite difference method (FLAC2D software), stability of wellbore in Shale formation has been surveyed.

The modeling was done in 3 modes of drilling. The first mode is drilling without pressurizing mud into the well, the second, drilling at a higher pressure than balance condition i.e. drilling mud pressure to be higher than the pore pressure. The third mode is underbalance condition in which the drilling mud pressure is lower than the pore pressure. The results of numerical modeling showed that the most displacements and plastic surface around the well occurred when the drilling mud was not pressurized. The displacement underbalance and over balance condition significantly decreased and the minimum amount of displacements and plastic surface around the well occurred at higher than balance condition.
Methodology and Approaches:
In this study, analysis of stability of wellbore and determination of the optimum mud pressure for wellbore stability has been carried out by elastoplastic method. If this value is less than the critical value defined by Normalized Yielded Zone Area (NYZA) the wellbore is considered to be stable.
Results and Conclusions: The results showed that the NYZA parameter is inversely proportional to the density of drilling mud, so that increasing drilling mud pressure and its density; results in more stable well bore and lower NYZA of the well. Based on NYZA method using numerical technique the critical value for wellbore stability is 1 and it can be realized from the surveyed well that the mud pressure over 22 MPa is within the scope of stability zone. Optimum mud pressure range obtained for the surveyed well is 33.02-33.71MPa for balance drilling and 35.09-35.78MPa for after balance drilling. All these data are obtained from Shale formation of one of the oil wells in Marun Field at a depth of 3915 meters.