نشریه مهندسی منابع معدنی
سال چهارم شماره 2 (تابستان 1398)

Structural systems related to iron ore mineralization in the Sangan mining region, northeastern Iran, have a direct relationship with the geometry of deformations. Fractures and faults, linear and planar structures and the influence of igneous bodies as the source of the fluids have the final effect of magmatism on mineralization. The purpose of this study was to investigate and identify the tectonic structures in C-North ore deposit, including a regional structural model with a structural model of ore deposit, and deposit formation model. Due to the location of the Sangan mining area at the end of one of the large-scale branching terminals of the Dorouneh fault, Sangan region is considered as part of the tectonic escape, and many structural functions in the area can be found in the Sangan ore deposits is due to the activity of this phenomenon. By investigating the existing faults in the area and performing a spatial density analysis for each fault series, a fault density map is generated which indicates the three fault systems in the C-North ore deposit. Based on intrusive body studies, the schematic diagram showing the probable accretion style, mechanism of outward building and exsolution of magmatic fluids during the emplacement of magma was presented along with the C-North ore deposit formation model. The results of studying of skarns and C-North ore deposits have great applied scientific significance and can be used for the study of skarn deposits.

Nowadays, recovery operations in oil reservoirs through water injection have a favourable economic approach, but the efficiency of this method decreases due to the formation of mineral deposits in super saturation. In the present study, formation of mineral deposits of barium sulphate and strontium sulphate has been studied and predicted during water imbibition operation in several oil fields such as Nosrat and Siri, according to the Extended UNICQUAC activity factor model. Based on the results of this study, the Extended UNIQUAC model is well matched to experimental and field results. Also, the prediction of barium sulphate and strontium sulphate precipitation in Nosrat oilfield depends on the conditions and composition of formation water, injected water (Persian Gulf water) and operational conditions, which can cause problems in surface and sub-surface equipment in oil exploitation operations. But for the Siri oil field, based on the analysis of water and operational data, the precipitation of barium sulphate and strontium sulphate is not significant. In this study, the temperature is 50, 100 and 110 °C, and also the pressure is 135, 270 and 2465 psi. The concentration of mineral salts in the water sample and injection water was up to 86,900 mg / l.

Ground vibration is one of the most unfavorable consequences of the blasting operation in open pit mines, which assign about 40 percent of explosive energy. Ground vibration may cause some unsuitable effects such as destroying the surface structures, damaging the free face and generate back breaks, generating the over-size boulders and imposing additional costs to the mine because of the secondary blasting. Optimum blasting pattern design can help to reduce the above mentioned problems. Due to multiplicity of effective parameters and complexity of interactions among these parameters, empirical methods may not be fully appropriate for blasting pattern design. In this paper, using a combination of the Grey analysis and Genetic algorithm, addition to developing a new equation for estimating the ground vibration in Sarcheshmeh Copper Mine, blasting pattern is presented. The results show that with applying the proposed blasting pattern the average ground vibration will be decreased about 55 percent.

In the world, high levels of severe damage are reported annually among persons in mines. One of the effective ways to provide the necessary safety in mines is to use a comprehensive management and planning system to determine the main hazards in the mines and respond to them. Therefore, in this paper, the hierarchy analysis method is used to evaluate and manage the safety risk in Chromit Faryab open-pit mines. According to a survey in four mines of Chromite Faryab, at first step, 78 risks identified. After a survey of 63 miner who work in the mines, 27 risks identified in 6 groups (geology, drilling and blasting, transportation, machinery and equipment, laws and regulations, and individual errors) as important risks. By using Fuzzy Analytical Hierarchy Process method 11 risks is identified as the main risks in the mines. The results show that the drilling and blasting group and individual errors are respectively (0.178 and 0.173), the most important of the risks in the Chromite Faryab mines. Finally, for each group of hazards, the appropriate risk is responded based on the incident documentations, the description of the experts and incidents in similar projects.

Hydraulic fracturing is used in the oil industry in order to increase the index of production and processing in wells whose efficiencies have been dropped due to long-term harvest or the rocks around the well are low permeable. Since the hydraulic fracturing operation is costly, it is of special importance to determine the pressure required for hydraulic fracturing and the suitable pump for this operation to the project managers. In this research, sandstone specimens of Lushan area were used and investigated the effect of thermal stress on hydraulic fracturing pressure of sandstone. The Hoek triaxial cell was adapted for a laboratory modelling of hydraulic fracturing. The specimens under study are in the shape of thick-walled hollow cylinders with an external diameter of 54.7 mm, an internal diameter of 12 mm, and a height of 108 mm. To study the effect of thermal stress, the tests were conducted on the specimens that heated up to 100 °C in the furnace at heating process and then cooled in water 5, 10 and 15 °C. Results indicated that hydraulic fracturing pressure reduced with decreasing Cooling temperature of samples. In hydraulic fracturing operations, this decreasing fracture pressure causes the pump to be purchased at a lower pressure production capacity, resulting in lower operating costs. Hydraulic fracturing pressure changes in the effect of thermal stress were consistent with the variations of velocity of longitudinal waves, dry unit weight, uniaxial compressive strength and permeability. CT scan images were used to examine micro cracks changes in the effect of thermal stress and the CT value calculated by the images confirms hydraulic fracturing pressure variations.

When comminution precedes mineral beneficiation processes, the liberation spectrum of the particles in a comminution process is of great importance. The calculation of the liberation spectrum in a continuous closed milling circuit is a vastly more difficult task. Here, a method has been incorporated into the CMCS simulation software to calculate the product size distribution and liberation spectrum in ball mills. The model requires a minimum amount of experimental data and is capable of calculating the detailed liberation spectrum. While, other existing methods account only for the completely liberated particles and a broad group of unliberated particles are not represented. An easy-to-use ball mill simulation environment has been developed and the results are compared with measured grinding data and previously existing simulators, particularly MODSIM, demonstrating firmly tested performance both in terms of accuracy and precision of obtained results.

In this research, Koosh mineral processing plant’ performance was investigated and troubleshot using systematic sampling. As there was no mass/volume flowmeter on the pipelines, process flow rates were calculated based on the mass balancing of notes using obtained gross samples data from different points of the plant. Obtained results indicated that about 10% Pb and 6% Zn were lost in the pre-flotation stage. Regarding the particle size of pre-flotation stage, entrainment was detected the main reason of Pb and Zn loss. Therefore, applying appropriate depressants and cleaning of the floated part can decrease Pb and Zn loss in the pre-flotation stage. Mass balancing results show that addition of the higher amount of reagents did not improve flotation recovery. Pb recovery generally was under 50% and Zn recovery did nor reached higher than 62%. Zinc loss to Pb final concentrate and lead and iron content in the Zn final concentrate was high. Consequently, in order to improve plant metallurgical efficiency using appropriate depressant, selective collectors, appropriate reagents distribution were recommended.

Flotation is the most frequently approach for beneficiation of metallic ores in mineral processing plants. Continuous control of flotation circuits is necessary to achieve optimum metallurgical performance. Previous research has established that there is a meaningful correlation between the froth visual features and process conditions and performance. The main objective of the current study is to develop algorithms for extraction of visual (bubble size, froth velocity and froth colour) and textural (energy, entropy and correlation) features from the froth images as well as classification of the images based on the captured properties. For this purpose, flotation tests were conducted in a batch cell under various process conditions and the metallurgical parameters (copper recovery and concentrate grade) along with the image variables were measured. Decision tree and fuzzy C-means algorithms were used for classification and clustering of the froth images. It was found that the developed machine vision system is capable of more accurately classifying the froth images than a manual operatory system. The results indicate that the developed algorithms are capable of accurately classifying the froth images with respect to the visual as well as the metallurgical parameters, which is of central importance for development of a machine vision based control system.