نشریه مهندسی منابع معدنی
سال هشتم شماره 3 (پاییز 1402)

Data integration can be used to conduct exploratory studies on a regional scale simultaneously on all available data from the study area. The results obtained by considering all the data and the relationship between them are more accurate and reliable. In these cases, mineral potential modeling is utilized to determine promising areas. Although GIS-based mineral prospectivity mapping methods have been established, it is important to review which methods of geochemical data analysis result in anomaly maps that, in turn, lead to better models of mineral prospectivity. In this study, instead of using anomalies of pathfinder elements, using geochemical zonality anomalies as one of the several evidential maps resulted in the improved mapping of mineral prospectivity. In addition, whereas weights-of-evidence analysis was used in this study, other methods of data representation and integration for mineral prospectivity mapping can be used. In this study, a part of Arasbaran metallogenic zone was selected and one-element geochemical control maps, geochemical maps produced by zonality, structural, alteration and geological maps were weighted and produced using the position of known indices by the method of weights-of-evidence. In the next step, weighted layers were combined with logistic regression (LR) method to prepare mineral potential models.

In order to design an appropriate dewatering system in an open pit mine, it is necessary to know the hydrogeological conditions and factors affecting the condition of groundwater in the mining area. One of the important factors for investigating the hydrogeological conditions of a mining site is to know the status of the catchment area, temporal and spatial changes of the piezometric levels and the range of disturbances caused by mining activities, climate conditions and the tectonic state of the mining area. The hydrological and hydrogeological conditions of Sangan iron mine are also affected by climate factors such as precipitation and tectonic factors including the number of faults and their trends, their distances and their relationship with each other. Therefore, in this study, the influence of various factors including precipitation, distance from waterways, tectonic status and faults, and the pit development during the exploitation period on the fluctuation of groundwater were investigated. By examining the fluctuations of the piezometric levels caused by these factors in the period from March 2011 to March 2014 and statistical analysis of the results, it was found that among the affecting factors, the Cn-pit expansion has the greatest effect on the groundwater level fluctuation of the western anomalies of Sangan mine. By drawing the ccorrelation diagram between the distance from Cn-Pit and the groundwater level drop of observation piezometers of the nearby areas of the Cn-pit, and obtaining a coefficient of determination equal to 0.94 (R2=0.94), it was found that the radius of the influence of the Cn-pit expansion on the changes in the groundwater level of the adjacent areas is about 700 meters. In addition, it was found that the amount of precipitation and the distance from the waterways do not have a significant effect on the groundwater level fluctuations in the study area.

Having rich mineral reservoirs, Iran has great potentials for developing this field, especially in copper mines. Mining in Iran has great potentials for helping economy and creating jobs. Studying and solving the problems of contractors and making necessary preparations for them in order to enter the mining industry and making investment in this area are of effective factors in actualizing the vast mining potentials in Iran. Existence of large-scale contractors in mining operations is considered not only an inseparable arm of the domestic large-scale mining body, but is also looked upon as the prerequisite for sustainable economic development. In any way, despite the undeniable benefits and necessity of large-scale mining contractors for working in large-scale mines, some strategic problems such as international sanctions, lack of access to quality mining machineries, lack of access to quality spare parts and up-to-date technologies, worn-out transportation, time-consuming process of finding spare parts due to sanction conditions, currency rate fluctuations, changes in stated inflation trend, etc., result in limiting contractors’ activities in the large scale. In this research, in addition to studying the major problems of contractors in large mines of Iran, the most important challenges of large-scale mining contractors, especially in large copper mines are reviewed and support solutions such as making preparations for importing up-to-date and large machineries and spare parts, adaptation of adjustment to inflation rate, making specific price list for mining industry, etc. for the continuity of mining contractors’ operations are presented.

Pile movement is one of the rock blasting outcomes that, considering the type of haulage machines, has a direct effect on the efficiency of the loading process. In this study, using UDEC discrete element software, the pile movement of fragmented material caused by the blasting operation is modeled. Since UDEC is not capable of modeling the whole process of rock blasting, to accurately model the pile movement of fragmented material, the damping coefficients must be changed in a way to allow the move freely out of the split blocks after the blast, be modeled. The numerical modeling results show that implementing a negative exponential function with three (the initial, threshold, and power) eigenvalues, as the fish-function to the damping coefficient, can model the results pile movement. With the help of this damping function, three blasting blocks with one and two rows of blast holes were modeled. The results of these modeling show that the pile movement for the two rows of blast holes depends on the inter-row delay time, and for the delay times of 17 ms and 50 ms, the maximum horizontal movement of the pile was 30 m and 55 m, respectively. These values show good agreement with the values measured in an actual blast operation. The results of this study show that by changing the negative exponential function eigenvalues defined for damping, the velocity of the fragmented blocks, the displacement, and the geometry of the pile, could be modeled. This shows the capability of the discrete element method in the modeling of the results of rock blasting.

Compressed air storage is one of the methods of energy storage. One of the most important parts of a compressed air storage system is the storage cavern. In this study, the behaviour and the long-term stability of the salt cavern as a storage site for compressed air were investigated. Due to the construction and operation of the salt cavern, the in-situ stress conditions around the cavern will change. The difference between induce stress and pressure of compressed air will cause the cavern to converge and damage around it. In this study, the salt rocks from one of the regions of Iran were used to test creep. To investigate the creep behavior of salt rock, creep test was performed in three stress levels in a stepwise manner. Lubby2 model parameters were calculated. Then, using LOCAS finite element software, the compressed air storage cavern was simulated and its behavior and stability were investigated. The results of these experiments and modelling have shown that with increasing stress in each stage, the slope of the secondary part of the creep increases. Therefore, it can be concluded that with increasing stress, the Maxwell viscosity coefficient decreases. In addition, the amount of movement in the lower half of the cavern was more than the upper half of it. Value of the cavern safety factor according to the Devries dilation criterion also decreased with increasing depth and the probability of dilation in the cavern wall increased.

The presence of copper oxide next to gold increases the consumption of cyanide in the cyanidation process, reduces the absorption of gold on carbon, and causes many problems in the downstream processes of elution, electrowinning, and smelting. In the current research, increasing the recovery of gold dissolution and its selective adsorption on activated carbon using ammonia additive and the effect of different factors such as the type of ammonia additive, changing the system of contact of gold with carbon from CIL to CIC, and adding hydrogen peroxide and cyanide to the filtered solution were studied. The findings showed that adding ammonium chloride or liquid ammonia to the cyanidation solution, in the sample with high copper grade (1% copper), and in the sample with medium copper grade (0.5% copper), increased the dissolution recovery by 60% and 30%, respectively. Also, the recovery of gold adsorption on activated carbon in sample with a grade of 0.5% copper increased from about 25% during the normal CIL process to about 100% during the ammonia cyanidation process in the form of CIC. Results showed that liquid ammonia provides up to 10% higher dissolution recovery and up to 3% higher absorption recovery compared to ammonium chloride, while reduces the consumption of cyanide by half and the amount of copper absorption on carbon by a third.

Sineqan mine, 25 km away from Delijan city (Markazi province), has shown important evidences of iron oxide ores containing copper, gold and rare earth elements (REE) in the early stages of exploration. In the present study, a low-grade sample of the mine from the albite zone containing 0.69% of copper and 223, 186 and 55 g/t of cerium, lanthanum and neodymium was processed and compared with the results of elements correlation in geochemical samples. Cerium, neodymium and lanthanum showed the highest correlation with each other and with the thorium. The correlation coefficient of light REEs with phosphorus was negative. The results of ammonium sulfate leaching showed that the occurrence of REE in the sample is not as adsorption on clay minerals and the study of the correlation coefficient of REE with aluminum and sodium in geochemical samples also confirmed this result. The results of leaching with H2SO4 showed that selective leaching of copper is possible. The low efficiency of leaching with H2SO4, HCl and HNO3 and the higher efficiency of 96% for leaching with cerium and lanthanum under acidic baking conditions showed that a significant part of REEs is in the form of refractory minerals. The concentration ratio of REEs in the magnetic concentrate was close to iron. According to the correlation analysis of elements in geochemical samples, the correlation of calcium with REE was in the range of -0.2to-0.3. In the flotation test, although the grade of calcium increased 3.5 times in the flotation concentrate, this was not the case for REEs. The results of this research can be used in similar cases in the early stages of exploration and processing feasibility studies.