1. Risk assessment of flyrock in surface mines using FFTA-MCDMs combination

raziye norouzi masir; Mohammad Ataei; Adel Mottahedi

Articles in Press, Accepted Manuscript, Available Online from 23 January 2020

Abstract

  The drilling and blasting method is the first choice for rock breakage in surface or underground mines due to its high flexibility against variations and low investment costs. However, ...  Read More The drilling and blasting method is the first choice for rock breakage in surface or underground mines due to its high flexibility against variations and low investment costs. However, any method has its own advantages and disadvantages. The flyrock phenomenon is one of the drilling and blasting disadvantages that the mining engineers have always been faced with in the surface mine blasting operations. Flyrock may lead to fatality and destroy mine equipment and structures, and so its risk assessment is very essential. For a flyrock risk assessment, the causing events that lead to flyrock along with their probabilities and severities should be identified. For this aim, a combination of the fuzzy fault tree analysis and multi-criteria decision-making methods are used. Based on the results obtained, the relevant causing events of flyrock in surface mines can be categorized into three major groups: design error, human error, and natural error. Finally, using the obtained probabilities and severities for these three groups, the risk matrix is constructed. Based on the risk matrix, the risk numbers of flyrock occurrence due to the design errors, human errors, and natural influence are 12, 6, and 2, respectively. Hence, in order to minimize the flyrock risk, it is very vital for the engineers to select appropriate values for the design events of blasting pattern such as burden, spacing, delays, and hole diameter.

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2. Dilution risk ranking in underground metal mines using Multi-Attributive Approximation area Comparison (MABAC)

Majid Mohseni; Mohammad Ataei; Reza Khaloo Kakaie

Articles in Press, Accepted Manuscript, Available Online from 25 December 2019

Abstract

  The contamination of ores with wastes or materials of lower than the cut-off grade is referred to as dilution. Dilution is an undesirable phenomenon that, on one hand, reduces the product ...  Read More The contamination of ores with wastes or materials of lower than the cut-off grade is referred to as dilution. Dilution is an undesirable phenomenon that, on one hand, reduces the product grade and, consequently, reduces the sales prices and, on the other hand, adds an extra cost to waste production. Therefore, studying and evaluating the dilution risk is important in mining, and especially in underground mining. In this work, using a powerful decision-making method, i.e. Multi-Attributive Approximation Area Comparison (MABAC), the dilution risk and ranking it in underground mines are assessed. For this purpose, the most important parameters affecting the dilution in 10 mines of the Venarch manganese mines are first identified and then weighed using the Fuzzy Delphi Analytical Hierarchy Analysis (FDAHP) method. Then using the MABAC method, the dilution risk score for each mine is estimated, and subsequently, various mines are ranked as the dilution risk. Then with the implementation of the Cavity Monitoring System (CMS) and measurement of the actual dilution values, the mines are ranked in dilution. The correct matching of the results of these two rankings indicates that the MABAC method is highly effective in the ranking of the risk. At the end, the risk ranking of the mines is done using the TOPSIS method, and the lack of full compliance with the results of this method with the actual values indicates that the MABAC method is preferable to the TOPSIS method.

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3. Application of Sequential Gaussian Conditional Simulation to Underground Mine Design Under Grade Uncertainty

F. Sotoudeh; M. Ataei; R. Kakaie; Y. Pourrahimian

Volume 11, Issue 3 , Summer 2020, , Pages 695-709

Abstract

  In mining projects, all uncertainties associated with a project must be considered to determine the feasibility study. Grade uncertainty is one of the major components of technical ...  Read More In mining projects, all uncertainties associated with a project must be considered to determine the feasibility study. Grade uncertainty is one of the major components of technical uncertainty that affects the variability of the project. Geostatistical simulation, as a reliable approach, is the most widely used method to quantify risk analysis to overcome the drawbacks of the estimation methods used for an entire ore body. In this work, all the algorithms developed by numerous researchers for optimization of the underground stope layout are reviewed. After that, a computer program called stope layout optimizer 3D is developed based on a previously proposed heuristic algorithm in order to incorporate the influence of grade variability in the final stope layout. Utilizing the sequential gaussian conditional simulation, 50 simulations and a kriging model are constructed for an underground copper vein deposit situated in the southwest of Iran, and the final stope layout is carried out separately. It can be observed that geostatistical simulation can effectively cope with the weakness of the kriging model. The final results obtained show that the frequency of economic value for all realizations varies between 6.7 M$ and 30.7 M$. This range of variation helps designers to make a better and lower risk decision under different conditions.

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4. Studying Relationship between Coal Intrinsic Characteristics in Spontaneous Combustion of Coal Potential Using Crossing Point Temperature Test Method

A. Saffari; M. Ataei; F. Sereshki

Volume 11, Issue 1 , Winter 2020, , Pages 315-333

Abstract

  Spontaneous combustion of coal is one of the most horrifying hazards in coal industries, especially in underground coal mines. Thus having a prior knowledge about the occurrence of ...  Read More Spontaneous combustion of coal is one of the most horrifying hazards in coal industries, especially in underground coal mines. Thus having a prior knowledge about the occurrence of this phenomenon in underground coal mines is of crucial importance in preventing this process, loss of life, huge economic loss, and environmental pollution. The aim of this work is to determine the spontaneous combustion of coal potential in the Tabas Parvadeh coal mines in Iran in order to assess the effect of coal intrinsic characteristics on its occurrence. For the purpose of this investigation, the coal samples were collected from Parvadeh I to IV, and the coal intrinsic characteristics of the samples were tested. In order to determine the spontaneous combustion of coal propensity in this case study, the Crossing Point Temperature (CPT) test was used. Then the relation between the coal intrinsic characteristics and the CPT test values was determined. The results obtained showed that the B1 seam in Parvadeh II and C1 seam in Parvadeh III had a high potential of spontaneous combustion of coal potential. These results also show that an increase in the moisture, volatile matter, pyrite, vitrinite, and liptinite contents enhance the spontaneous combustion of coal tendency in these mines. The results obtained have major outcomes for the management of this phenomenon in the Tabas Parvadeh coal mines. Therefore, evaluation of the spontaneous combustion of coal hazards in coal mines should start in the first stage of design and carried on during their whole lifecycle, even after mine closure.

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5. A Mathematical Model to Optimize Allocation Sequence in Dispatching Problem

M. Ghobadi Samani; M. Monjezi; J. Khademi Hamidi; A. Mousavinogholi

Volume 11, Issue 1 , Winter 2020, , Pages 185-192

Abstract

  Truck-Shovel fleet, as the most common transportation system in open-pit mines, has a significant part of mining costs, for which optimal management can lead to substantial cost reductions. ...  Read More Truck-Shovel fleet, as the most common transportation system in open-pit mines, has a significant part of mining costs, for which optimal management can lead to substantial cost reductions. Among the available dispatch mathematical models, the multi-stage approach is well suited for allocating trucks to respected shovels in a dynamic dispatching program. However, with this kind of modeling sequencing of the allocated trucks is not possible though it is important to find out the best solution so that getting the minimum accrued cost. To comply with the shortcoming of the traditional model, in this paper, a new hybrid model is developed and applied in Copper Mine of Iran, in which for each truck an allocation matrix is considered as input to the genetic algorithm implemented to determine the best solution. According to the obtained results, the optimal sequencing of the trucks can result in a significant (31%) cost reduction in a shift.

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6. Use of a mixed integer programming model to achieve an optimum size of blast block in open-pit mining with regard to size of mineable block using fuzzy logic approach

A. Mozafari; A. H. Bangian Tabrizi; M. Taji; A. Parhizkar

Volume 10, Issue 4 , Autumn 2019, , Pages 1095-1104

Abstract

  In this paper, we present an integrated model to find the optimum size of blast block that uses (i) a multi-criteria decision-making method to specify the applicable size of the mineable ...  Read More In this paper, we present an integrated model to find the optimum size of blast block that uses (i) a multi-criteria decision-making method to specify the applicable size of the mineable block; (ii) a linear programming method for the selection of the blasted areas to be excavated and in deciding the quantity of ores and wastes to be mined from each one of the selected blocks. These two methods use improved estimates of the orebody characteristics utilizing the blast hole data in addition to the usual borehole statistics to improve the prediction accuracy of the block level ore body characteristics. This work aims to make a mathematical model to figure out the ideal width and length of the blast block in order to curtail drilling and blasting expenses in open-pit mines. As a consequence, the effective blast block size is heeded so as to decrease the expenses of drilling and blasting. Furthermore, a complete set of actual principles is presented to specify the applicable size of the mineable block by means of the multi-criteria decision-making method of fuzzy logic. The aforementioned model is practiced to forecast the block size necessary for the purpose of production planning. Next, a mixed integer programming model is developed to blast planning in order to select the optimal size of the blast block by considering the mineable block. The proposed model is applied in the Chadormalu iron ore mine and the rationality of the model is demonstrated by the outcomes of dissimilar circumstances.

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7. Analysis of reliability and maintainability for multiple repairable units (Case study: Sungun copper mine)

R. Razzaghzadeh; R. Shakoor Shahabi; A. Nouri Qarahasanlou

Volume 10, Issue 4 , Autumn 2019, , Pages 1045-1059

Abstract

  The appropriate operating of mining machines is affected by both the executive and environmental factors. Considering the effects and the related risks lead to a better understanding ...  Read More The appropriate operating of mining machines is affected by both the executive and environmental factors. Considering the effects and the related risks lead to a better understanding of the failures of such machines. This leads to a proper prediction of the reliability parameters of such machines. In this research work, the reliability and maintainability analysis of the loading and haulage machines in the Sungun Copper Mine, considering the repair condition as multiple repairable units, was performed. For this purpose, the data necessary for the loading and haulage equipment including 2 loaders and 8 dump trucks for a 15-month period was collected and categorized in 10 operational units after the system and sub-systems of the department were determined. Initially, the time between failures (TBFs) and time to repair (TTR) for each unit was calculated. Then 20 sub-systems were developed. Primarily, the Stata software was utilized to carry out the heterogeneity test for all the sub-systems. In consequence, most of the sub-systems were regarded as the heterogeneous ones, except for 7 of them including the dump truck units 1, 2, 3, 4, 5, 7, and 8 in TBFs. Hence, "PHM" that is a covariate-based model displayed the heterogeneous group. Its reliability function was also estimated. For the next step, the trend tests were done on the non-heterogeneous sub-systems by means of the Minitab software. The homogeneous sub-systems with failure trend were modeled by “NHPP”. Afterwards, the non-trended sub-systems formed the data group. Later, the correlation tests were modeled by “HPP”. Finally, the reliability and maintainability functions were calculated with the 95% confidence level.

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8. Application of simulated annealing for optimization of blasting costs due to air overpressure constraints in open-pit mines

H. Bakhshandeh Amnieh; M. Hakimiyan Bidgoli; H. Mokhtari; A. Aghajani Bazzazi

Volume 10, Issue 4 , Autumn 2019, , Pages 903-916

Abstract

  Estimating the costs of blasting operations is an important parameter in open-pit mining. Blasting and rock fragmentation depend on two groups of variables. The first group consists ...  Read More Estimating the costs of blasting operations is an important parameter in open-pit mining. Blasting and rock fragmentation depend on two groups of variables. The first group consists of mass properties, which are uncontrollable, and the second one is the drill-and-blast design parameters, which can be controlled and optimized. The design parameters include burden, spacing, hole length, hole diameter, sub-drilling, charge weight, charge length, stemming length, and charge density. Blasting costs vary depending on the size of these parameters. Moreover, blasting brings about some undesirable results such as air overpressure, fly rock, back-break, and ground vibration. This paper proposes a mathematical model for estimating the costs of blasting operations in the Baghak gypsum mine. The cost of blasting operations in the objective function is divided into three parts: drilling costs, costs of blasting system, and costs of blasting labours. The decision variables used to minimize the costs include burden, spacing, hole diameter, stemming length, charge density, and charge weight. Constraints of the model include the boundary and operational limitations. Air overpressure in the mine is also anticipated as one of the model constraints. The non-linear model obtained with consideration of constraints is optimized by simulated annealing (SA). After optimizing the model by SA, the best values for the decision variables are determined. The value obtained for the cost was obtained to be equal to 2259 $ per 7700 tons for the desired block, which is less than the blasting costs in the Baghak gypsum mine.

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9. Airflow inside tunnel boring machine: A numerical study and an experimental verification

H.R. Nezarat; Seyed M. E. Jalali; M. Nazari

Volume 10, Issue 3 , Summer 2019, , Pages 623-632

Abstract

  Knowledge of the airflow distribution inside a Tunnel Boring Machine (TBM) can create a safe working environment for workers and machinery. The airflow quality and the related mass ...  Read More Knowledge of the airflow distribution inside a Tunnel Boring Machine (TBM) can create a safe working environment for workers and machinery. The airflow quality and the related mass flow rate in the ventilation system should be sufficient to dilute gases and remove dust inside the tunnel. In this work, airflow distribution in the single shield TBM tunnel was studied using computational fluid dynamics. The finite volume-based finite element method was used in the simulation based on the 3D complex geometry of TBM. In order to validate the numerical results, the air velocity inside the Chamshir tunnel was measured experimentally at different sections. With a length of 7050 m and a final diameter of 4.6 m, the Chamshir water transport tunnel is located in the south of Iran. The results obtained show that there is not enough airflow in 59.6% of the TBM space in the current working conditions. In other words, there are many dead zones from the control cabin to the end of gantry 6 in the backup system. Several applicable scenarios were studied to remove the dead zone area and optimize the airflow velocity by employing high capacity jet fan in the ventilation system. The results show that the dead zone volume can be decreased by about 5.21% by increasing the airflow rate of the jet fan.

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10. Analysis of a possible root cause and mechanism for Soma mine disaster

B. Ünver; M.S. Ünal

Volume 10, Issue 1 , Winter 2019, , Pages 1-26

Abstract

  A daunting mine disaster took place in 13 May 2014 at Soma and 301 men lost their lives. Brief information about the Eynez coal mine and some of the inherent characteristics of the ...  Read More A daunting mine disaster took place in 13 May 2014 at Soma and 301 men lost their lives. Brief information about the Eynez coal mine and some of the inherent characteristics of the field in terms of their effects on mining are presented. This paper basically concentrates on the factors that played an important role in the occurrence of this disaster. Progress of mine fire, firefighting, and rescue activities were only given in basics. Mine fire started suddenly without giving any sign at the hearth of the mine. Sudden occurrence of mine fire and start location properties reveal that the root cause of this disaster was probably not directly related to spontaneous heating of coal. Analysis of roof caving mechanism, subsidence profiles, production history, and overall conditions in the mine showed that the mine fire most probably started as a result of a sudden caving above the nearby sealed out old production panels. Upon caving, pressure of the gas present in uncaved voids and unconsolidated goaf must have increased and gas must have overflown through abundant cracks towards the mine. Gas exuding under moderate pressure might possibly be ignited by a non-ex-proof belt conveyor drive motor starting the mine fire.

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11. A new classification system for evaluation and prediction of unplanned dilution in cut-and-fill stoping method

M. Mohseni; M. Ataei; R. Khaloo Kakaie

Volume 9, Issue 4 , Autumn 2018, , Pages 873-892

Abstract

  Production planning in mineral exploitation should be undertaken to maximize exploited ore at a minimum unplanned dilution. Unplanned dilution reduction is among the ways to enhance ...  Read More Production planning in mineral exploitation should be undertaken to maximize exploited ore at a minimum unplanned dilution. Unplanned dilution reduction is among the ways to enhance the quality of products, and hence, reduce the associated costs, resulting in a higher profit. In this way, firstly, all the parameters contributing to unplanned dilution in underground stopes and specifically the cut-and-fill stoping method are identified. Secondly, the parameters are weighed using the fuzzy-Delphi analytical hierarchy process. Thirdly, the most effective parameters are selected among the pool of effective parameters. Finally, in order to present a novel classification system for an unplanned dilution assessment, a new index called stope unplanned dilution index (SUDI) is introduced. SUDI represents the extent to which a cut-and-fill stope is susceptible to unplanned dilution. That is, having the value of this index, one may classify the cut-and-fill stopes into five groups according to robustness versus unplanned dilution: very strong, strong, moderate, weak, and very weak. SUDI is applied to10 stopes in different parts of Venarch Manganese Mines (Qom, Iran). In this way, a semi-automatic cavity monitoring system is implemented in the stopes. The regression analysis method shows that there is a relationship between SUDI and the actual unplanned dilution in equivalent linear overbreak/slough with a correlation coefficient (R2 = 0.8957).

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12. Estimation of reliability-based maintenance time intervals of Load-Haul-Dumper in an underground coal mine

J. Balaraju; M. Govinda Raj; C.H.S.N. Murthy

Volume 9, Issue 3 , Summer 2018, , Pages 761-770

Abstract

  Reliability estimation plays a significant role in the performance assessment of mining equipment, and aids in designing efficient and effective preventive maintenance strategies. Continuous ...  Read More Reliability estimation plays a significant role in the performance assessment of mining equipment, and aids in designing efficient and effective preventive maintenance strategies. Continuous and random/irregular occurrence of failures in a system could be the main cause for performance drop of machinery. The accomplishment of a projected level of production is possible only by an efficient operation of the equipment. In order to improve the equipment life, a critical analysis of failure/breakdown occurrences is required to be carried out, and appropriate remedial measures need to be designed and implemented to enhance reliability. This paper presents a reliability analysis of Load-Haul-Dumper (LHD) in an underground coal mine. The goodness-of-fit distribution of each LHD was made through the Cramer-Von-Mises statistic test. The parameters involved were estimated using both the maximum likelihood analytical estimation process and the graphical process. Further, an attempt was made to reduce the total cost of operation by estimating the reliability-based preventive maintenance time intervals.

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13. Prediction of the main caving span in longwall mining using fuzzy MCDM technique and statistical method

S. Mohammadi; M. Ataei; R. Khaloo Kakaie; A. Mirzaghorbanali

Volume 9, Issue 3 , Summer 2018, , Pages 717-726

Abstract

  Immediate roof caving in longwall mining is a complex dynamic process, and it is the core of numerous issues and challenges in this method. Hence, a reliable prediction of the strata ...  Read More Immediate roof caving in longwall mining is a complex dynamic process, and it is the core of numerous issues and challenges in this method. Hence, a reliable prediction of the strata behavior and its caving potential is imperative in the planning stage of a longwall project. The span of the main caving is the quantitative criterion that represents cavability. In this paper, two approaches are proposed in order to predict the span of the main caving in longwall projects. Cavability index (CI) is introduced based on the hybrid multi-criteria decision-making technique, combining the fuzzy analytical network processes (ANP) and the fuzzy decision-making trial and evaluation laboratory (DEAMTEL). Subsequently, the relationship between the new index and the caving span is determined. In addition, statistical relationships are developed, incorporating the multivariate regression method. The real data for nine panels is used to develop the new models. Accordingly, two models based on CI including the Gaussian and cubic models as well as the linear and non-linear regression models are proposed. The performance of the proposed models is evaluated in various actual cases. The results obtained indicate that the CI-Gaussian model possesses a higher performance in the prediction of the main caving span in actual cases when compared to the other models. These results confirm that it is not possible to consider all the effective parameters in an empirical relationship due to a higher error in the prediction.

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14. Application of VENTSIM 3D and mathematical programming to optimize underground mine ventilation network: A case study

S. Maleki; F. Sotoudeh; F. Sereshki

Volume 9, Issue 3 , Summer 2018, , Pages 741-752

Abstract

  Ventilation is a vital component of an underground mining operation, used to guarantee a safe atmosphere for workers and survive them from the hazardous and toxic gases. In the recent ...  Read More Ventilation is a vital component of an underground mining operation, used to guarantee a safe atmosphere for workers and survive them from the hazardous and toxic gases. In the recent years, engineers have begun to apply new operation research techniques in order to optimize the ventilation systems to assist in achieving a regulatory compliance, reduce ventilation costs, and improve its efficiency. Airflow regulation optimization in mine ventilation networks is described as a minimization model whose objective function is a minimum number of regulators and energy consumption. In this work, all the previously accomplished works were first reviewed. Then a ventilation system was designed for the Western-Razmja coal mine by a manual method, and an axial fan was proposed. Subsequently, the same ventilation system was simulated using the VENTSIM 3D software. The results obtained by computer simulation showed that there was a reliable relation between the manual method and the simulation approach. In the final step, the GAMS software was used to solve a Mathematical Programming (MP) problem to minimize the overall cost of ventilation by determination of the optimum location for the fan and regulators. The final results of this work illustrated that not only the number of regulators were reduced through solving the MP model but also the total resistance of the Western-Razmja coal mine was reduced by 14% from 1.6 to 1.3. Furthermore, it was observed that the total efficiency of the proposed fan was increased.

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15. Determination and assessment of coal bed methane potential using rock engineering systems

K. Ghanbari; M. Ataei; F. Sereshki; A. Saffari

Volume 9, Issue 3 , Summer 2018, , Pages 605-621

Abstract

  The presence of methane in coal mines is one of the major problems in underground coal mines. Every year, in underground coal mines, a lot of casualties due to outbursts and explosions ...  Read More The presence of methane in coal mines is one of the major problems in underground coal mines. Every year, in underground coal mines, a lot of casualties due to outbursts and explosions of methane gas is occurring. Existence of this gas in the mines not only creates a difficult and dangerous situation for work but also makes it more expensive. The release of this gas to the air causes a further pollution of the atmosphere and increases the greenhouse gases in the air. Thus Coal Bed Methane (CBM) drainage before, during, and after coal mining is necessary. Accordingly, the CBM drainage can reduce the risks involved in these mines. In the past decade, CBM has offered a significant potential to meet the ever-growing energy demand and can decrease the disastrous events. In this research work, the CBM potential in Eastern Kelariz, Western Razmja, Bornaky, Bozorg, Razzi, and Takht coal mines of Eastern Alborz coal mines company is investigated using the rock engineering systems (RES) based on the intrinsic and geological parameters. Nine main parameters are considered for modeling CBM, and the interactions between these parameters are calculated by a proposed system. Based on the RES method, the parameters that are dominant (depth of cover) or subordinate (gas content) and also the parameters that are interactive are introduced. The proposed approach could be a simple but efficient tool in the evaluation of the parameters affecting CBM, and hence be useful in decision-making. The results obtained show that Razzi coal mine has a good potential to perform CBM drainage.

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16. Estimation of coal seams gas content for evaluating potential use of methane drainage system in Tabas coal mine

M. Mohtasham Seyfi; J. Khademi Hamidi; M. Monjezi; A. Hosseini

Volume 9, Issue 3 , Summer 2018, , Pages 667-677

Abstract

  Methane gas emission, accumulation, and explosion are the most important risk factors in underground coal mines. Hence, having a knowledge of methane gas emission potential in underground ...  Read More Methane gas emission, accumulation, and explosion are the most important risk factors in underground coal mines. Hence, having a knowledge of methane gas emission potential in underground coal mines is of crucial importance in preventing the explosion risk, loss of life, and property, and providing miners' safety. The purpose of this work is to provide the prediction maps for the C1, C2, and B2 coal seams gas contents, and to identify high gas content panels in the Parvadeh No. 1, Tabas coal mine. For this, the data collected from exploratory boreholes is put into geostatistical analysis in ArcGIS in order to estimate the coal seams gas content in unsampled points using the kriging estimation method. Reviewing the gas content maps has revealed that seams of C1, B2, and C2 have gas contents more than 15 cubic meters per ton in about 84%, 55%, and 22% of the understudied area, respectively. The present work highlights the potential and the need for implementation of a methane pre-drainage system, particularly in deeper longwall panels.

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17. Application of stochastic programming for iron ore quality control

J. Gholamnejad; A. Azimi; M.R. Teymouri

Volume 9, Issue 2 , Spring 2018, , Pages 331-338

Abstract

  Stockpiling and blending play a major role in maintaining the quantity and quality of the raw materials fed into processing plants, especially the cement, iron ore and steel making, ...  Read More Stockpiling and blending play a major role in maintaining the quantity and quality of the raw materials fed into processing plants, especially the cement, iron ore and steel making, and coal-fired power generation industries that usually require a much uniformed feed. Due to the variable nature of such materials, they even come from the same source and the produced ores or concentrates are seldom homogeneous enough to be directly fed to the processing plant ore furnaces. Processing plants in iron ore mines need uniform feed properties in terms of each variable (in this work, iron phosphorous ratio and Fe content in magnetite phase) grade of ore, and therefore, homogenization of iron ore from different benches of an open pit or ore dumps has become an essential part of modern mine scheduling. When ore dumps are considered as an ore source, the final grade of the material leaving the dump to the blending bed cannot be easily determined. This difficulty contributes to mixing the materials of different grades in a dump. In this work, the ore dump elements were treated as normally distributed random variables. Then a stochastic programming model was formulated in an iron ore mine in order to determine the optimum amount of ore dispatched from different bench levels in open pit and also four ore dumps to a windrow-type blending bed in order to provide a mixed material of homogenous composition. The chance-constrained programming technique was used to obtain the equivalent deterministic non-linear programming problem of the primary model. The resulting non-linear model was then solved using LINGO. The results obtained showed a better feed grade for the processing plant with a higher probability of grade blending constraint satisfaction.

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18. A practical approach to open-pit mine planning under price uncertainty using information gap decision theory

M. M. Tahernejad; M. Ataei; R. Khalokakaie

Volume 9, Issue 2 , Spring 2018, , Pages 527-537

Abstract

  In the context of open-pit mine planning, uncertainties including commodity price would significantly affect the technical and financial aspects of mining projects. A mine planning ...  Read More In the context of open-pit mine planning, uncertainties including commodity price would significantly affect the technical and financial aspects of mining projects. A mine planning that takes place regardless of the uncertainty in price just develops an optimized plan at the starting time of the mining operation. Given the price change over the life of mine, which is quite certain, optimality of the proposed plan will be eliminated. This paper presents a risk-averse decision-making tool to help mine planners in mining activities under price uncertainty. The objective is to propose mine planning in a way that a target Net Present Value (NPV) is guaranteed. In order to reach this goal, Information Gap Decision Theory (IGDT) is developed to hedge the mining project against the risk imposed by the information gap between the forecasted and actual price. The proposed approach is of low sensitivity to the price change over the life of mine, and can use the estimated prices with uncertainty. A case study at an existing iron mine demonstrates the performance of the proposed approach. The results obtained showed that the proposed method could provide a robust solution to mine planning under price uncertainty. Moreover, it was concluded that the method could present more reliable mine plans under condition of price uncertainty.

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19. Simulation of tunnel boring machine utilization: A case study

S. Moosazadeh; H. Aghababaie; Seyed H. Hoseinie; B. Ghodrati

Volume 9, Issue 1 , Winter 2018, , Pages 53-60

Abstract

  Utilization is one of the main managerial factors that is applied for construction process analysis well. It directly affects the project duration and construction costs. Therefore, ...  Read More Utilization is one of the main managerial factors that is applied for construction process analysis well. It directly affects the project duration and construction costs. Therefore, a utilization study in tunneling projects is essential. In this work, the utilization of an earth pressure balance Tunnel Boring Machine (TBM) in Tabriz urban railway project was studied using the Monte Carlo simulation approach. For this purpose, the unit operation during one working shift such as boring time, ring building time, and locomotive travel time was recorded and saved in data base. In addition, the general down times such as TBM and back-up system maintenance, surface and tunnel logistic maintenance, cutting tools’ replacement, and locomotive delay times were recorded and considered in simulation. The results of this work show that the mean simulated project duration time of case study TBM is approximately 859 shifts and close to the real data with a difference of 0.92%. Finally, the average estimated utilization factor was found to be approximately 14%.

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20. UPL determination of multi-element deposits with grade uncertainty using a new block economic value calculation approach

M. Jamshidi; M. Osanloo

Volume 9, Issue 1 , Winter 2018, , Pages 61-72

Abstract

  The block economic value (BEV) of a single-metal deposit is calculated based on the metal content and the related costs. The common methods available for calculating BEV are just based ...  Read More The block economic value (BEV) of a single-metal deposit is calculated based on the metal content and the related costs. The common methods available for calculating BEV are just based upon the profitable elements, and the effects of undesirable elements on BEV are not considered. However, in multi-element deposits, the effects of other elements existing in the blocks on BEV should be considered with the purpose of optimizing the blending. These elements and blending methods have considerable effects on the quality of the final product. In this paper, a new approach is introduced to determine BEV in multi-element deposit with two types of profitable and penalty elements by considering the effect of blending on BEV. Consequently, the ultimate pit limits (UPLs) will be determined based on these conditions. The developed model is tested in the Gol-e-Gohar No.2 iron-ore mine, and the mine UPLs is determined. The results obtained showed that the mineable reserve of the pit increased by 3% when the effects of both types of elements are considered. In order to investigate the effect of grade uncertainty on BEV, twenty realizations of the ore block are generated using the sequential Gaussian simulation approach. The UPLs of all the realizations are determined using the developed BEV-calculation method, and the pit limits with different probabilities of occurrence are determined. The total mineable reserve varied between 20,380 and 46,410 million tons. The exploitation of mine should start with the smallest pit (100% probability). The largest pit should be considered as a guide for surface-facility locating.

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21. Development of a site-specific regression model for assessment of road-header cutting performance of Tabas coal mine based on rock properties

E. Ghasemi

Volume 8, Issue 4 , Autumn 2017, , Pages 663-672

Abstract

  In underground excavation, where the road-headers are employed, a precise prediction of the road-header performance has a vital role in the economy of the project. In this paper, a ...  Read More In underground excavation, where the road-headers are employed, a precise prediction of the road-header performance has a vital role in the economy of the project. In this paper, a new model is developed for prediction of the road-header performance using the non-linear multivariate regression analysis. This model is able to estimate the instantaneous cutting rate (ICR) of roadheader based on rock properties such as Brazilian tensile strength (BTS), rock mass cuttability index (RMCI), and alpha angle (α: is the angle between the tunnel axis and the planes of weakness). In order to construct and test the proposed model, a database including 62 cutting cases is used in the Tabas coal mine No. 1 in Iran. Various statistical performance indices were employed to evaluate the model efficiency. The results obtained indicate that the proposed non-linear regression model can be efficiently used to predict the road-header cutting performance. Furthermore, the prediction capacity of this model is better than the empirical models developed previously. Finally, it should be noted that the developed model is site-specific, and it can be used for preliminary estimation of ICR in future phases of Tabas coal mine No. 1. The outcome of this model can be helpful in adjustment of time-scheduling of the project.

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22. Optimal production strategy of bimetallic deposits under technical and economic uncertainties using stochastic chance-constrained programming

E. Bakhtavar; A. Jafarpour; S. Yousefi

Volume 8, Issue 3 , Summer 2017, , Pages 475-485

Abstract

  In order to catch up with reality, all the macro-decisions related to long-term mining production planning must be made simultaneously and under uncertain conditions of determinant ...  Read More In order to catch up with reality, all the macro-decisions related to long-term mining production planning must be made simultaneously and under uncertain conditions of determinant parameters. By taking advantage of the chance-constrained programming, this paper presents a stochastic model to create an optimal strategy for producing bimetallic deposit open-pit mines under certain and uncertain conditions. The uncertainties of grade, price per product, and capacities of the various stages in the process of production of the final product were considered. The results of solving the deterministic and stochastic models showed that the stochastic model had a greater compatibility and performance than the other ones.

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23. Development of a goal programming model for optimization of truck allocation in open pit mines

M. Mohtasham; H. Mirzaei Nasirabad; A. Mahmoodi Markid

Volume 8, Issue 3 , Summer 2017, , Pages 359-371

Abstract

  Truck and shovel operations comprise approximately 60% of the total operating costs in open pit mines. In order to increase productivity and reduce the cost of mining operations, it ...  Read More Truck and shovel operations comprise approximately 60% of the total operating costs in open pit mines. In order to increase productivity and reduce the cost of mining operations, it is essential to manage the equipment used with high efficiency. In this work, the chance-constrained goal programing (CCGP) model presented by Michalakopoulos and Panagiotou is developed to determine an optimal truck allocation plan in open pit mines and reduce the waiting times of trucks and shovels. The developed goal programming (GP) model is established considering four desired goals: “maximizing shovel production”, “minimizing deviations in head grade”, “minimizing deviations in tonnage feed to the processing plants from the desired feed” and “minimizing truck operating costs”. To employ the developed model, a software is prepared in Visual Studio with C# programming language. In this computer program, the CPLEX optimizer software is incorporated for solving the developed goal programing model. The case study of Sungun copper mine is also considered to evaluate the presented GP model and prepared software. The results obtained indicate that the developed model increases the mine production above 20.6% with respect to the traditional truck allocation plan, while meeting the desired grade and the stripping ratio constraints.

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24. Determination of a suitable extraction equipment in mechanized longwall mining in steeply inclined coal seams using fuzzy analytical hierarchy method (Case study: Hamkar coal mine, Iran)

A. Hosseini; M. Najafi; Seyed A. Shojaatlhosseini; R. Rafiee

Volume 8, Issue 3 , Summer 2017, , Pages 487-499

Abstract

  The longwall mining method is one of the most applied methods in extracting low-inclined to high-inclined coal seams. Selection of the most suitable extraction equipment is very important ...  Read More The longwall mining method is one of the most applied methods in extracting low-inclined to high-inclined coal seams. Selection of the most suitable extraction equipment is very important in the economical, safety, and productivity aspects of mining operations. There are a lot of parameters affecting the selection of an extraction equipment in mechanized longwall mining in steeply inclined coal seams. The important criteria involved are the geometric properties of coal seam (dip, thickness, and uniformity of coal seam), geological and hydraulic conditions (faults, fractures, joints, and underground water), and geomechanical properties of coal seam and surrounding rocks. Extraction of inclined coal seams with gradients greater than 40 degree is different from low-inclined seams, and requires a special equipment. Therefore, the influence of the above-mentioned parameters must be considered simultaneously in the selection of extraction equipment for steeply inclined seams. This paper presents an application of the Fuzzy Analytical Hierarchy Process (FAHP) method in order to select a suitable extraction equipment in the Hamkar coal mine. In the proposed FAHP model, fifteen main criteria are considered, as follow: dip of coal seam, thickness of coal seam, seam uniformity, expansion of coal seam, faults, fractures and joints, underground waters, hangingwall strength, footwall strength, coal strength, in-situ stress, equipment salvage, dilution, system flexibility, and operational costs. Among the 6 considered longwall extraction equipment system alternatives, the findings show that the most suitable extraction equipment system is shearer on footwall and a support system using hydraulic props and the transport of coal with the force of gravity.

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