عزالدین بخت آور

The production cycle in open-pit mines includes the drilling, blasting, loading, and haulage. Since loading and haulage account for a large part of the mining costs, it is very important to optimize the transport fleet from the economic viewpoint. Simulation is one of the most widely used methods in the field of fleet design. However, it is unable to propose an optimized scenario for which the appropriate metaheuristic method should be employed. This paper considers the Sungun copper mine as the case study, and attempts to find the most feasible transportation arrangement. In the first step, in this work, we compare the flexible dispatching with the fixed allocation methods using the Arena software. Accordingly, the use of flexible dispatching reveals the increase in the production rate (20%) and productivity (25%), and the decrease (20%) in the idle time. The firefly metaheuristic algorithm used in the second step shows that the combined scenario of the 35-ton and 100-ton trucks is the most suitable option in terms of productivity and cost. In another attempt, comparing different heterogeneous truck fleets, we have found that the scenarios 35-100 and 35-60-100-144 increase the production rate by 39% and 49%, respectively. Also, in both scenarios, the production cost decreases by 11% and 21%, respectively.

Determining the transition limit from the open pit mining to an underground mining method is one of the key decisions where there is the possibility to mine using both open pit and underground mining methods. Transition level is a depth where open pit mining is the best choice above this depth and underground mining is prioritized below it regarding the technical and economic aspects. In the early-stage mine planning studies, including the determination of transition limit, simplicity, practicality, and quickness of decision making are of the requirements, while achieving the acceptable answers is regarded. In this research, a practical approach based on combining Lerchs and Grossman algorithm and the Equilibrium Stripping Ratio (ESR) method is proposed to determine the transition limit. For this purpose, firstly nested and developing pits are generated with the objective of maximizing the net present value (NPV), then the Incremental Stripping Ratios (ISR) of each of these optimal developing pits are calculated. According to the alternative underground mining method(s), the ESR is calculated and finally, the transition limit will be determined comparing the ISR of these developing pits and the calculated ESR. In the present research, this approach is applied to determine the transition level in an iron ore deposit. To verify the determined transition limit, calculating the cumulative net present value shows that mining by underground method below the determined transition level can increase the NPV by 23% compared to continuing open pit mining.

 Tunneling under the water table is a compatible condition for projects. Most important consequences of tunneling in this situation are water inrush, bad working condition, mudflow, low advance rate, and humans injuring. Especially for TBM tunneling that required high investments funds, these hazards can impose high costs for a project. This paper estimates water inflow by the finite element method in the second part of Emamzade Hashem tunnel and providing risk management for these hazards using the FMEA method. 

The second part of Emamzade Hashem tunnel is the longest road tunneling project in Iran that will be excavated by a TBM. TBM tunneling in hard rock and faulty zone have lots of hazards that may cause many stops in the project according to previous similar projects around the world. Risk management could classify hazards and make them predictable and controllable.

In this paper, water flow ratio was estimated by numerical simulation with FLAC 2D. In the following, the classical risk of water inrush was calculated by the FMEA method with studding some similar projects. A fuzzy analysis was then applied to increase the accuracy of the results. To this end, after estimating water inflow for each section of the tunnel, the time and costs of each hazard were calculated by studying similar projects. Risk number was estimated and managed through the FMEA method based on the calculations. The reduction actions were suggested for the hazards with high-risk numbers.

The results of the study indicated that tunneling in the middle part of the tunnel has high risk due to high water pressure according to classical and fuzzy analysis. It has resulted that the performance of fuzzy analysis is higher than classical analysis.

The occupational and health hazards associated with working in coal mines are known as the main concerns despite the high importance of coal production in the economic development of countries. Irreparable damages to personal and financial losses can be avoided if the effective factors result in the occupational risks of underground coal mines are identified. In this research, these factors were initially identified in the case of underground coal mines in Iran. Then, the direct and interaction effects of the identified factors were evaluated and determined using fuzzy cognitive map approach that is based on the analysis of the cause and effect interaction between the identified effective factors. Results indicated that dust concentration, individual negligence and mistakes, inappropriate and inadequate ventilation, errors in design, planning, and execution, and the volume and concentration of methane gas are respectively determined the important factors caused the occupational hazards in the underground coal mines of Iran. The statistical study of the accidents occurred in Iran's underground coal mines, especially recent events, confirms the results of this research.

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.

In underground coal mines, due to occurrence of probable events and the consequent risks, normally a reliable safe environment is not provided for the work forces and operational equipments. Through the risks, two main considerable damages may happen. First, the human injuries namely fatality, disability or maim and organ fractures and second the economical damages such as amortization and loss of mining equipments, and closure of working faces and galleries. Considering these types of crucial events this study aims on reducing the likely risks particularly in East Alborz Coal Mines Company. For this purpose, based on probability of event occurrences, their severities and outcomes the relevant risks have been assessed and analyzed. To achieve this goal by taking into account the occurrence probability and intensity a number of measures or standards were developed by the authors. Risk Priority Number (RPN) was introduced. By employing RPN the most impressive uncertainty factor in East Alborz Coal Mines Company was recognized. Finally, with the regard to the degree of damages caused by the events, a practical procedure for risk reduction in the mines has been presented.