IRANIAN JOURNAL OF MINING ENGINEERING (IRJME)
Year:2022 | Volume:17 | Issue:57|Papers Count:7

Tunneling projects are implemented over a relatively long time due to the limited work environment. In this case, project management and implementation optimization are very important. Various methods can be used to control and manage the project. Network methods are one of the effective methods. . The CPM and PERT methods are the most commonly used. The GERT method is also one of the most efficient networking methods and can be used for situations where there are potential activities in addition to time. Due to the complexity of the operation and also the unknown geological conditions in the tunneling, in addition to the uncertain timing of some activities, not all activities are necessarily definitive and some activities will not be performed depending on the conditions in each project. Therefore, in this study the used of GERT method in tunneling has been investigated and an example is shown for its used. In this example, first different tunneling operations are outlined for the project of constructing a large cross-section tunnel. Then, according to the type of each activity, the likelihood of execution and the time interval of execution are defined. Due to the technical and operational conditions, the relationship between activities based on the GERT network was shown. The method of network analysis was expressed in both manual and software. A numerical example was implemented using Risk Analysis Primavera software and different completion times were obtained for different project percentages. Conversely, the corresponding probability times can also be set for different predicted times. The project execution time is 2981 days with 50% probability and 3082 days with 80% probability.

Optimization of haulage system in open pit mines is very important due to its high operating costs. Till now a large no. of researches have been conducted to optimize the truck fleet size in an open pit mine in dispatching and non-dispatching modes. These researches have gained many achievements in this regard and still they are going to continue. On the other hand, nowadays, application of artificial intelligence is spreading vastly to optimize systems in the field of (mining) engineering, especially in np-hard problems. One of the new meta-heuristic algorithms in engineering field is Imperialistic Competition (IC), which is developed primarily for electrical systems. Recently, it has found its application in the field of mining systems as well. In this paper, application of IC algorithm for optimization of haulage system in open pit mines is introduced. Implementation of the IC algorithm for Songon Copper mine was validated with comparison of its results with those of Genetic algorithm. Comparison showed promising results. Optimization of the system with IC algorithm improves the mine production from 32 thousand tons as the current situation to 37 thousand tons, while optimization of the system with Genetic algorithm improves the mine production to 35 thousand tones.

Generally, Mine ventilation is based on the analysis of fluids. The main fluid in mine ventilation is air fluid. Based on the science of fluids, air-fluid shows different behaves in different conditions. In the fluid analysis method of the ventilation science, air-fluid can be analyzed from several different perspectives such as dry model, wet model, incompressible model, and compressible model. Researchers have used various models of fluid analysis in mine ventilation and most of them believe that the real conditions for designing mine ventilation are to consider two conditions: humid air and compressible fluid analysis. Accordingly, in this paper, different fluid analysis conditions were considered for designing mine ventilation and the results show that compressible fluid analysis for humid air needs to be solved by two nonlinear equations. Therefore, it requires numerical calculation methods. One of the most common methods in numerical calculations is the Newton-Raphson method. This method is defined based on the derivative. Using this method for solving these nonlinear equations increases the volume of mathematical calculations. Therefore, in this paper, two Delta (Δ) and K methods are presented to facilitate the solution of these two nonlinear equations and reduce the error of mathematical calculations. Delta (Δ) and K methods have been defined based on thermodynamic rules for analyzing compressible humid air in mine ventilation design. Also, the amount of evaporation rate of water should be known in these methods. The results show that these two methods have a simpler and better performance.

In recent years, the use of processed mineral resources in the science of civil engineering has gained a wide scope. Some of these materials, such as slag-furnace-slag, can improve adhesion and filling in the structure of concrete due to the presence of abundant silica-aluminate materials in them. In this laboratory research, a mixing design was made of ordinary concrete with a cement grade of 450 kg/m3. A mixing design was also made of activated alkali concrete based on blast furnace slag to compare and evaluate the tensile strength of concrete under ambient temperature and heat of 500 degrees Celsius, at the age of 90 days. Next, X-ray diffraction (XRD) and scanning electron microscope (SEM) images at the processing age of 90 days at ambient temperature and under heat of 500 ℃, in order to further investigate and verify the results of the resistance test. Tensile testing was done on concrete samples. The obtained results indicate that the tensile strength at ambient temperature is 5.048 MPa for ordinary concrete and 4.41 MPa for activated alkali concrete, which had a difference of 12.63%. By applying high heat to the concrete samples, the amount of tensile strength drop in normal concrete reached 51% and in alkali activated concrete 21%. The results of the XRD and SEM tests were in agreement with each other and overlapped with the results of the tensile strength test.

Zarshuran mine located at 35 km north of Takab city in an area of about 37 square kilometers at a distance of 7 km from Zarshuran village and consists of sulfide minerals such as pyrite, ralgar, overpement, arsenopyrite, stebenite, sphalerite, galen and cinnabar. About 55 to 60% of the gold in this ore is in solid solution inside the crystal lattices of pyrite and arsenopyrite and this has caused the resistance of gold ore in the cyanation process to increase and the percentage of gold recovery in the cyanation process to decrease. Therefore, ferric ion oxidation method was investigated to release gold from sulfide minerals and under optimal conditions, ion ferric concentration of 11 g / l, time 8 hours, temperature 45 ° C, pH equal to 1 and pulp density 25% recovery Gold increased to 72%, while under direct cyanation process without oxidation with ferric ion, the maximum recovery of gold was 41%, which shows that the oxidation process with ion ferric can increase the recovery of gold in the cyanation process by 31%.

The increasing use of concrete and easy access to these materials has led to its use in a variety of environments. Concrete structures in areas with high corrosion rates cause irreparable damages. Therefore, studying concrete and improving its capabilities, which is favorable in these conditions, is very important. In this study, the effect of corrosion conditions caused by chlorine ion and sodium sulfate salt on concrete containing zeolite powder and micro silica as an alternative to the weight percentage of concrete cement has been investigated. In this study, after creating three types of ordinary concrete, concrete containing zeolite powder and concrete containing micro-silica, physical properties of concrete including effective porosity, weight loss percentage, water absorption, and longitudinal wave velocity, as well as mechanical properties including uniaxial compressive strength and Brazilian tensile strength concrete has only been studied. In this study, pozzolanic concrete with a percentage of replacing 10% of zeolite powder or micro-silica instead of cement; Sodium sulfate and chlorine ion were set in a corrosive medium for 15 days, and the results were compared with non-corrosive water conditions. The results of this study show that concretes containing pozzolanic micro-silica or zeolite powder performed better in corrosive and non-corrosive environmental conditions than ordinary concrete. In samples containing pozzolans including micro-silica and zeolite powder with effective porosity, water absorption decreased, and longitudinal wave velocity, tensile and compressive strength increased compared to ordinary concrete. Also, in the presence of corrosive water conditions containing chlorine ion and sodium sulfate salt, concrete containing zeolite powder had the best performance compared to the two types of ordinary concrete and concrete containing micro-silica.

Back-up locomotives are locomotives responsible for mechanized excavation of tunnels, transport of prefabricated concrete parts, slurry poured behind prefabricated concrete parts and foams, as well as materials excavated from the tunnel. In this study, the reliability, availability and maintainability of back-up locomotives of EPB-TBM machines of Tabriz metro line 1 have been investigated. Initially, locomotives were divided into four main systems, including pneumatic, electrical, hydraulic and motor. Each of these systems, in turn, consisted of subsystems. Then, the failure data of 5 locomotives were collected; after combining the data, about 30,000 hours of data were obtained from the failures. Examination of the data showed that there was a failure in ten subsystems and these subsystems were critical. Pareto analyzes were then performed to examine the percentage of failures, costs, and repair times. For each subsystem, the most appropriate failure distribution function was fitted and the reliability of the subsystems and systems was determined. Due to the lack of a trend in all failure data and the prevalence of independent and equal conditions for the data, reliability and availability were matched. Also, using the average repair times, the maintainability of the components was determined. The results indicated the importance of reliability for pneumatic, electrical, motor and hydraulic systems, respectively. Meanwhile, the pneumatic system is very different from the other three systems, and over time, this difference becomes even greater. Another very important result is the loss of reliability of almost all subsystems to below 50% after 500 hours of operation. In the maintenance section, the results also showed that all failure times were higher than 400 hours. In terms of repair times, a significant part was related to the hydraulic system, followed by the engine and pneumatic system with the most repair time.