نشریه مهندسی منابع معدنی
سال ششم شماره 4 (زمستان 1400)

Northwestern part of Iran is one of the important metal bearing zones and the Baluqaya region which is one of the interesting parts of this area, was selected as the study area. In this research the endmembers were extracted from ASTER dataset and then were compared with spectral library to find matching reference minerals for them. Subsequently, the abundances of endmembers were exracted using the matched filtering technique. Then, the classification and distribution maps of minerals were extracted by implementing the floating threshold as a novel technique on endmembers abundance maps. The mineralogical data of the study area are also involved in the floating threshold method. This method classifies areas with high abundance values of endmembers that probabily have high potential for mineralization. The results delineated argillic and advanced argillic alterations at the midwest of the study area. By performing of robust principal component analysis (RPCA) on ICP-MS geochemical data, correlation of gold concentrations with that of antimony and arsenic was detected in the remote sensing derived alteration area. Finally, it is concluded that a possible high sulfidation epithermal mineralization system has developed in the study area

The interpretation of the pressure data of naturally fractured reservoirs (NFRs) has particular significance. The most famous theory for analyzing the pressure data of NFRs is the dual-porosity model presented by Warren and Root. Recent studies have shown that the dual-porosity model may not be appropriate for interpreting well test from all NFRs because this model has limits. In this study, the pressure transient response of naturally fractured reservoirs was investigated by using numerical simulation without considering analytical and semi-analytical methods. To this end, a set of models including connected and disconnected fracture networks was simulated in the numerical simulator. The Warren and Root well-testing signature was observed in all simulations but it was highly evident for a well was located in the matrix and was negligible for a well that was intersected by fractures. The results of the simulation for the well that was intersected by fractures showed the bilinear flow regime with the slope of 1/4. The period of this flow regime increased in the unconnected fracture network and changed to the linear flow regime with a slope of 1/2 in two cases: firstly, by increasing fracture permeability in the connected fracture network, secondly, in the small-unconnected fractures. Moreover, the sensitivity analysis was performed on the well location in the connected fracture network. This research showed that by decreasing the distance between well and fracture network, the transition period becomes deeper and appears earlier.

Appropriate drill bit selection can lead to enhance remarkable drilling operation efficiency and cost-saving. There are several factors affecting the bit selection process. Among these parameters, some factors such as specific energy (SE), cost per foot (CPF), formation drillability (FD), and rate of penetration (ROP) are considered the most important ones. One of the best approaches to select the optimum drill bit is to apply Multiple Criteria Decision-Making (MCDM) techniques. In this research work, Fuzzy Technique for Order-Preference by similarity to Ideal Solution (FTOPSIS) is used to choose the optimum bit for drilling operations in Sarvak and Asmari formations due to higher accuracy and validity of findings achieved from the FTOPSIS. With this respect, three types of bits (i.e. 517, 527, and 537) were considered as available candidates and were then ranked through the FTOPSIS, resulting in the best option (bit). In Asmari formation, similarity factors for bit types of 517, 527, and 537 bits were obtained as 0.479, 0.438, and 0.382, respectively indicating bit type 517 can be chosen as a proper option compared to other ones. Similarly, in Sarvak formation, results showed 0.5405, 0.5019, and 0.5622 values for 517, 527, and 537 bit types respectively, demonstrating the bit-type 537 is the most appropriate alternative in such formation.

In terms of longitudinal ventilation design, critical velocity and its estimation are the two most important parameters in a tunnel fire. Critical velocity must be accurately selected to provide safe conditions in a closed environment such as tunnels. This study is focused on fires in curved tunnels using a small-scale model (in a 1/20 scale) experiments and Computational Fluid Dynamics (CFD) simulations. Heat Release Rate (HRR) is considered as one of the key parameters in all numerical studies and physical experiments of the fire. In this study, a numerical study was carried out to evaluate the Heat Release Rate in pool fire Simulation in FDS software and small physical scale experiment. In the first step, grid sensitivity analysis and its impact on HRR estimation were investigated. The critical velocity of the physical model was equal to 0.90m/s and 0.92m/s in the numeric model. After data validation, it was concluded that increasing the HRR increases the critical velocity, so based on the results of the changes, it can be seen that this parameter is very important in estimating the critical velocity. But, this trend only dominates a certain range and the results show that outside of this range, the critical velocity is independent of the amount of HRR. On the other hand, the trend of increasing the critical velocity compared to the heat release rate for the curved tunnel, with a difference of about 10%, is in a higher position than the straight tunnel.

In this paper, the effect of PDC cutter angle on the failure mechanism of rock like materials was investigated using experimental test and numerical simulation. For this purpose, three PDC cutter with different angle were built, i.e. 0°, 30° and 60°. Nine gypsum sample with dimension of 14cm*11cm*5cm were prepared. The ratio of gypsum to water was equal to 2. For each PDC angle, three similar gypsum blocks were tested. The blocks were situated above the PDC cutters and these assemblies were fixed in Uniaxial test machine. The loading rate was 0.05 mm/min. concurrent with experimental test, numerical simulation was performed using particle flow code in two dimension. Firstly calibration of PFC was done using experimental results. Secondly, numerical model with dimension of 14cm*11cm was prepared. Then, five PDC cutter angles were built, i.e. 0°, 15°, 30°, 45° and 60°. These cutters were situated at lower part of the model and move in positive side of y direction by rate of 0.01 mm/min. the results show that failure patterns were affected by PDC angle. Also maximum failure load was controlled by failure pattern. The maximum failure load was decreased by increasing the PDC cutter angle. The maximum failure load was related to angle of 0. The minimum failure load was related to angle of 60. The experimental results were similar to numerical simulations out puts.

Mining is an upstream industry in the supply of industrial raw materials. The large volume of mine tailings as well as the considerable concentration of toxic pollutants, resulted from mining activities, cause irreparable damage to the surrounding environment. The leakage of toxic elements from the mine tailings to the environment is considered as a crucial issue. Therefore, the management of mine tailings is an important approach to reduce environmental damage. The reuse of mine tailings in concrete industry is considered as one of the main management techniques to reduce their probable adverse effects. In this study, the tailings of Sungun copper mine were collected to investigate their applicability in concrete construction instead of fine-grained materials. The results revealed that the concentrations of copper, arsenic, lead, chromium, cobalt, and nickel in copper mine tailings were higher than the environmental criteria but less than the amounts required for economic recovery. Thus, tailings with a grain size of less than 297 μm were used in the construction of two series of concrete samples to replace 50 and 100% of the fine-grained part of the concrete. Moreover, some experiments including concrete slip, compressive strength, resistance to chlorine penetration, and TCLP were performed to ensure the applicability of copper mine tailings in concrete construction. In samples where copper tailings replaced 50 and 100% of fine-grained materials, the 28-day compressive strength was 32 and 41 MPa, respectively. The compressive strength increased with increasing replacement rate. According to the results, the highest leachate rates of copper, chromium, lead, zinc, cobalt, cadmium, and arsenic were 21, 2.8, 3.9, 106, 75, 0.39, and 0.82 mg/L, respectively. Thus, it could be concluded that if copper tailings are used in concrete, the amount of heavy metals leachate will be reduced to values below the environmental criteria level.

The cleaner circuit at Miduk copper concentrator consists of 3 parallel flotation columns (4m in diameter and 12m in height). The cleaner concentrate is re-cleaned by 3 parallel flotation columns (3.2m in diameter and 12m in height), when the desired concentrate grade is not reached by the cleaner columns alone. This research work deals with simulation of the cleaner column flotation circuit at Miduk copper concentrator using USIM PAC simulator with the aim of improving the process metallurgical performance. For that purpose, the parameters of the models including flotation rate constants (kf, ks), residence time distribution (RTD), gas hold-up in collection zone (εg), mean bubble size (db), collection (Rc) and froth (Rf) zone recoveries along with some operating and geometrical variables were determined. The flotation rate constants were calculated by fitting the experimental data to the fast and slow floating components model. The residence time distribution of the flotation columns was measured by the tracer injection technique (using saturated NaCl solution as tracer). The gas hold-up and mean bubble size in the collection zone of the cleaner columns were estimated from the pressure difference and the drift flux techniques, respectively. The froth recovery was quantified by measuring the concentrate mass flow rate at different froth depths and extrapolation to the zero froth depth. The cleaner circuit was sampled five times, of which three times were used for calibration and two times for validation of the models. The mass flow rate, copper content and size distribution of the cleaner columns concentrate and tailings were accurately predicted using the simulation models. Increasing the number of operating cleaner columns improved the copper recovery (from 45.67% to 54.64%) at the expense of a reduction in the final concentrate (from 26.17% to 24.22%). The number of recleaner stages in all cases improved the the final concentrate (from 26.17% to 36.99% in the circuit with 2 cleaners and from 24.22% to 36.13% in the circuit with 3 cleaners). Increasing the feed slurry solids concentration reduced the size-by-size fractional copper recovery of the cleaner columns. Increasing the feed slurry solids concentration reduced the cleaner columns copper recovery in all size fractions. The best configuration of the cleaner and recleaner flotation columns was proposed.

The purpose of this study was to introduce and investigate a new combination of collectors and their effect on flotation efficiency of Sarcheshmeh Copper Complex. In this study, the chemical composition of 2, 5-dimercapto-1, 3 and 4-thiadiazole (DMT ) as a new collector at pH values between 10 and 11.8 was tested. A review of scientific references and research records showed that DMT has not been used as a collector or in combination with other collectors in the flotation process so far. Nine experiments were performed to determine the collector performance as well as 6 additional experiments to determine the effect of different collector values. Based on the results, using DMT collector at pH 11.2, the recovery percentage and copper grade were achieved 88.2 and 11.9, respectively, which was 2.1 and 3.9% higher than the plant conditions, respectively. In this case, the separation efficiency was increased by 17%. Also, the recovery and grade of iron concentrate decreased by 17.1% and 4.8%, respectively. FTIR analysis was showed that during the adsorption process, the DMT form was changed from the tion-thiol form before chemical adsorption to the dithiol form after chemical adsorption. Also, the adsorption behavior of DMT on the chalcopyrite surface was limited in the chemical equilibrium between the extra-ring sulfur atoms and the metallic copper.

The present study aims to investigate the slag leaching of Sarcheshmeh copper reverberatory furnace using sulfuric acid and hydrogen peroxide. The results of the analyses indicated that the slag contains 0.7% of copper and 37.75% of iron. Most of the slag minerals include fayalite, magnetite, diopside and chalcopyrite. This research scrutinizes the effect of different parameters including the size of particles, temperature, PH, the concentration of hydrogen peroxide and the velocity pulp stirring on the recovery of copper and iron. Based on the results, as the size of particles of slag is reduced from 150- 250 to 48-74 micron, the maximum recovery of copper and iron is increased from 23.03% and 22.34% to 26.14 and 28.12%, respectively. However, as the size of particles is diminished less than 48 microns, less increase is detected in the recovery of copper and iron. When the pulp PH is reduced from 2.4 to 1.5, the recovery amount of copper and iron is increased from 18.12% and 20.95% to 29.14% and 31.04%, respectively. Changing the primary concentration of hydrogen peroxide affected the copper recovery the most. Increasing the concentration of hydrogen peroxide from 0.5 M to 2 M enhances copper recovery from 29.14% to 54.12%. Increasing the pulp temperature from 35 to 45°c subjected to enhance copper recovery from 53.5% to 59.5%. In fact, the enhancement of temperature to 50°c mostly influenced iron recovery. Using the hematite nano- particles in the leaching process leads to improve the function of hydrogen peroxide and increase the copper recovery.