The Effect of Layers Elastic Parameters on Hydraulic Fracturing Propagation Utilizing Displacement Discontinuity Method
Mahmood
Behnia
author
Kamran
Goshtasbi
author
Mohammad
Fatehi Marji
author
Aliakbar
Golshani
author
text
article
2012
per
Hydraulic fracturing as a method for reservoir stimulation depends on the properties of the media that fracture propagates in it. The elastic properties of layers greatly affect the geometry and propagation of hydraulic fractures. In this research study, the hydraulic fracturing propagation in multi-layered media (stiff and soft) with different elastic properties is investigated. Therefore, boundary element method based on the displacement discontinuity formulation is presented to solve general problems of hydraulic fracturing propagation in layered formations. The crack tip element and a higher order boundary displacement collocation technique are used to increase the accuracy of the method (2DFPM) in modeling of non-homogenous media. The stress intensity factor and tensile stress near the crack tip under different elastic modulus are evaluated to study the hydraulic fracture propagation. Related to the position of the fracture with interface (vertical, intersect and parallel) these factors have different values and finally, they control the fracture propagation. In comparison between the width of fractures in soft and stiff layers, the study displays that the fracture width in soft layers is greater than width of fracture in stiff layers.
Journal of Analytical and Numerical Methods in Mining Engineering
Yazd University
2251-6565
2
v.
3
no.
2012
1
13
https://anm.yazd.ac.ir/article_242_bbf2564d5692124dbb4551c452419494.pdf
Geostatistical Studies for Grade Variability Estimation and Designing an Optimized Sampling System for the SeChahoon Beneficiation Line Feed of the Choghart Iron Ore Plant
Asieh
Norasteh
author
Farhad
Mohammad Torab
author
Afshin
Namiranian
author
text
article
2012
per
Se-chahun beneficiation line is constructed for concentrating of low grade Se-chahun iron ore. The purpose of this article is designing an optimized sampling, studying of grade variability and blending system of the Se-chahun line feed. For this purpose, the optimum sampling weight is determined using 2-weight method that is equal to 0.49Kg and the number of sub-samples is calculated by means of corresponding error formulas that is equal to 29 samples. By means of variogram modeling, the optimum sampling period is calculated 110 hours. Grade variability can be reduced by fit bed blending. The blending is simulated by means of moving average method in different time period for reducing variability and grade fluctuation to increase plant recovery and concentrate quality. Finally, 65 hours for optimum blending is computed. Therefore, according to the rate of feed flow that is equal to 628t/h, optimum blending has been calculated as 40820ton. The control charts, confirm grade variability reduction into the specification grade limits.
Journal of Analytical and Numerical Methods in Mining Engineering
Yazd University
2251-6565
2
v.
3
no.
2012
14
24
https://anm.yazd.ac.ir/article_243_743a749df809936e6e2084961522ca4e.pdf
Application of Statistical Tests to Analyze Results of Chalcopyrite Particles Produced by Different Milling
Mahdi
Mohseni
author
Mahmood
Abdollahi
author
Seyyed Mohammadjavad
Koleini
author
text
article
2012
per
This paper presents a statistical evaluation for the shape parameters of different mill products for chalcopyrite mineral. The aim of this study was to determine the effect of grinding mechanisms on chalcopyrite shape properties. Image Analysis (IA) method was used to determine shape factors of chalcopyrite particles. The shape characters are stated in terms of shape factors such as aspect ratio, circularity, roundness, convexity and regularity factors. Applying analysis of variance (one way ANOVA) method followed by multiple comparison tests could show whether the shape parameters of the three different mill products were statistically different from each other or not. Statistical studies were performed using the SPSS software and obtained results showed that with a 95% confidence level, the difference between the shape properties of particles produced by different mill are significant and different grinding mechanism in rod mill, ball mill and ceramic ball mill affects the shape properties of particles. Increasing the role of attrition in grinding increases the circularity, convexity and roundness of particles so the ceramic ball mill makes circular particles and rod mill makes elongated particles.
Journal of Analytical and Numerical Methods in Mining Engineering
Yazd University
2251-6565
2
v.
3
no.
2012
25
34
https://anm.yazd.ac.ir/article_244_f06fa2da0fb1fd4701d5e5f4dbbec390.pdf
Identification and Separation of Anomall Variable Using Correspondence and Discriminant Analyses Methods at Northern–Dalli Area
Farshad
Darabi Golestan
author
Reza
Ghavami Riabi
author
Mohammadjavad
Majlesi
author
Mojtaba
Memarzadeh
author
Houshang
Asadi Harouni
author
text
article
2012
per
Urumieh–Dokhtar volcanic belt is considered as potential area of mineralization that includes majority of porphyry-type mineralization in Iran. According to the satellite imagery, regional visits and samples which were taken from Dalli, this area was introduced as an occurrence with high potential for the mineralization. 149 geochemical samples from secondary lithogeochemical environments (soil) have been studied in the current paper. Correspondence analysis and discrimination analysis are used as statistical methods to identify mineralization type and associated elements with mineralization. Reduction of data volume, identification the anomaly and evaluation of enriched and depleted element are important purposes from application of these methods. In the correspondence analysis the mineralization variables (elements) and samples were simultaneously identified. According to this survey, some of the samples such as 86, 46, 74, 22, 40, 84 and a number of other samples have emphasized a Cu-Au anomaly. In the discrimination analysis according to proven mineralization (Cu-Au) in area and previous result, Co concentration was shown a correlation with Cu-Au mineralization and La, Na and Mg are probably depleted in mineralization area. In the correspondence analysis, elements of K, Fe, Ti, and to some extent Ba almost were enriched in the Cu-Au mineralized area and elements As, Sr, Ca, Li, Na and some other were depleted.
Journal of Analytical and Numerical Methods in Mining Engineering
Yazd University
2251-6565
2
v.
3
no.
2012
35
43
https://anm.yazd.ac.ir/article_247_9a25846cf3862347ba66239af6cea04d.pdf
Application of Conditional Sequential Gaussian Simulation in Uncertainty Assessment of the Estimated Blocks Grade in Sordid Phosphate Mine
Ahmadreza
Sayyadi
author
Nader
Fathianpour
author
Aminollah
Mousavi
author
text
article
2012
per
Ore reserve amount and grade are critical variables in determining technical and economical indicators. These factors always associate with uncertainty. Therefore it is essential to assess risk along with them by using appropriate methods. One of these methods is conditional simulation that allows providing probability maps and determining orebody risk rate. Unlike the common geostatistical estimation methods which involve some sort of smoothing, conditional simulation provides a tool for quantifying risk rate along with grade and design and planning parameters. In this research sequential Gaussian simulation has been applied to assess the uncertainty associated with reserve grade and tonnage of Esfordi phosphate mine and prepared confidence interval and E-type maps. Finally, the rate and the effect of estimated risk have been assessed and analyzed. According to simulation result, ore reserve of Esfordi mine is between 12/212 and 18/835 tones and the average of ore amount is 15/269 with average grade of 16/8%. The results show 30% -risk with blocks
Journal of Analytical and Numerical Methods in Mining Engineering
Yazd University
2251-6565
2
v.
3
no.
2012
44
52
https://anm.yazd.ac.ir/article_248_0adebc0c6e0a183bc0bc7dfa58d9d9df.pdf
Estimation of Applied Stresses on Pillars in Stope and Rib Pillar mining Method by Numerical and Empirical Methods in Fetr 6 Chromite Mine
Saeid
Dehghan
author
Kourosh
Shahriar
author
Parviz
Maarefvand
author
Kamran
Goshtasbi
author
text
article
2012
per
Fetr6 is one of the Iran’s underground mines in which chromite had been extracted with room and pillar mining method. In Phase 1 of this mine, after the occurrence of a large scale failure, mining operations ceased and the stope and rib pillars mining method with delayed backfill was designed for phase 2. To design pillars in this method, it was necessary to understand the values of applied stress on pillars. Therefore, widespread and thorough studies were carried out to obtain them for this research. The values of applied stresses on pillars were estimated by numerical and empirical methods. Also, the effects of depth and sequence of ore extraction were investigated using both methods more precisely. The results show that while the plastic zone is not created in pillars, the estimated values by empirical methods are maximum 35% more than the real values and pillar position in the layout of mine is an important parameter on its stress values. But there are not meaningful differences between two methods when plastic zone is created in pillars.
Journal of Analytical and Numerical Methods in Mining Engineering
Yazd University
2251-6565
2
v.
3
no.
2012
53
61
https://anm.yazd.ac.ir/article_249_9c4701aaa7ac9440d088fa367f44240b.pdf
Multi-Objective Optimization of the Zarand Coal Washing Flotation Circuit Configuration by an Oriented Genetic Algorithm
Dorna
Pirouzan
author
Mohsen
Yahyaei
author
Samad
Banisi
author
text
article
2012
per
In flotation, it is customary to use more than one stage to achieve an acceptable level of separation of valuable minerals. Flotation circuit design is usually accomplished using empirical rules which at most cases they do not operate at optimum conditions. In design and optimization of flotation circuits, genetic algorithms could be used. In flotation circuit configuration optimization problem, metallurgical parameters such as yield and ash content could be used as the fitness function for the algorithm. Since there is a tradeoff between the yield and concentrate ash content (i.e., they move in opposite directions), multi-objective optimization methods are needed. Optimization of the Zarand coal processing plant flotation circuit was carried out by two methods: sum of weighted factors and Pareto optimum. The results indicated that it is possible to increase the yield from 57.6% for the current configuration to 65.8% for the proposed one. This was achieved by a three-stage configuration while keeping the quality of the concentrate ash content (10.9%) within an acceptable level.
Journal of Analytical and Numerical Methods in Mining Engineering
Yazd University
2251-6565
2
v.
3
no.
2012
62
69
https://anm.yazd.ac.ir/article_250_a0bf8b5769ca8cd0dfbd1c2059bd5945.pdf
Determination of Relation Between Uniaxial Compressive Strength with Point Load Index, Unit Weight and Porosity by Using Artificial Neural Network
Hosseinali
Lazemi
author
Mohammadreza
Eskandari
author
text
article
2012
per
Uniaxial compressive strength is one of the important and essential parameters in rock mechanics projects. This parameter is determined base on specific standards in laboratory. uniaxial compressive strength can be determined by direct method and with uniaxial compressive test that this method consumes time and cost. In some cases it is preferred to determine this parameter by indirect method. Accordingly it is necessary to establish logical relationship between this parameter and other physical and mechanical parameters of rock. Researchers provided a great relationship based on data from tests conducted on various rocks, because of the restrictions is not applicable to all areas and so it is necessary to improve relations for various points. In this study, in addition to previous studies, the parameters that influence rock uniaxial compressive strength are studied in the area of central of Iran and Bafgh. Using rock mechanics tests and artificial neural networks a relation is established for determining uniaxial compressive strength based on porosity, point load index and density parameters.
Journal of Analytical and Numerical Methods in Mining Engineering
Yazd University
2251-6565
2
v.
3
no.
2012
70
75
https://anm.yazd.ac.ir/article_251_3a698f28e8248d583528665aad5cf036.pdf
Fundamentals of the Probability Plot Modeling for Gravity Anomaly Separation in Compare with the Common Methods
Somayeh
Tabasi
author
Reza
Ghavami Riabi
author
Faramarz
Doulati Ardejani
author
text
article
2012
per
The gravity anomalies include gravity effects of underground structures and ore bodies, which have different densities and located in different depths. Anomaly separation methods such as trend analysis, filtering and analytical continuations, discriminate and separate the residual data from the regional components and reveal the position of the underground structures and ore bodies in the study area. Although there were some improvements in anomaly separation methods in the past decades, but there are in doubts in the determination of the anomaly boundaries. On the other hand, the removed regional anomalies still contain the effects of the residual values, which are anomaly values in reality. Modeling of raw data on probability plots is a method for determination of regional and residual trends (different sub- populations) and the exact threshold value for each effect or component (or sub-population). In this method, the data shows the boundaries of different components (regional and residual). The basic theory of probability plots modeling have been compared with the common gravity anomaly separation methods in this paper.
Journal of Analytical and Numerical Methods in Mining Engineering
Yazd University
2251-6565
2
v.
3
no.
2012
76
81
https://anm.yazd.ac.ir/article_252_3b90b740c8376e57859e3374dc69fe1b.pdf