نشریه مهندسی منابع معدنی
سال پنجم شماره 1 (بهار 1399)

In this study, processing and interpretation methods in remote sensing such as visual and spectral analysis have been performed on the ASTER (advanced spaceborne thermal emission and reflection radiometer) data from northeast of neyriz area, and as a result, the alteration zones in the area have been identified. Then, the results of magnetometric data, using geological information, alteration and mineralization from the have been interpreted. The emergence and expansion of a measuring instrument for geological and mineralogy in the field of mine mineral resources in recent decades are due to the importance of this industry. The study area is located in the northeast of neyriz and near the village of Ghori in Fars province. Geologically, the units of the study area are located in the zone-Sanandaj-Sirjan and with the general northwest-southeastern trend.

Identification of geochemical anomaly patterns, which indicate the enrichment and depletion of elements, is an important issue in the interpretation of geochemical data. The use of the power spectrum-area fractal method allows the better separation of geochemical populations that is due to transformation of the data from spatial domain to frequency domain. By implementing this method on the dataset of Au and Sb element contents obtained from chemical analysis of soil samples taken Sari Gunay exploration zone, three models including noise, anomaly and background maps were prepared for each element. The data of the noise maps constitute 5-6 percent of the primary data variation range and indicate sampling and analysis errors and rapid changes due to the distribution of elements in different rocks. Anomaly maps those variation range is similar to the variation range of initial data, represent enrichment locations and precise positioning of surface geochemical anomalies. However, background maps that cover about 12-18 percent of the variation range of primary data indicate the general trend of the concentration variations in the study area and the approximate location of geochemical anomalies. Anomaly map that shows the mineralization centre can be used to design a preliminary drilling network and the background map that shows the mineralization area, can be used to design drilling network in preliminary and detailed exploration phases. Anomaly and background maps have proposed Sari Gunay and Agh Dagh deposits areas and a new area for gold exploration. Besides, they have suggested Sari Gunay and Agh Dagh deposits areas and the fault area between two deposits for antimony exploration.

Mass production and the high rate of block caving have caused to special considerations in operational optimization of these mines. In caving mines, the uniform extraction not means as equal extraction from blocks. In the uniform caving, controlling of caving propagation is one of the most critical factors in the stability of caving mines. Selection of advancement direction is one of the most important constraints in block caving and in the advancement direction controlling one of the critical aspects related to blocks precedency. So the goal of this research is to determine block precedence according to caving direction. It is crucial to control and validate the advancement direction to reach an optimum scheduling program. In this paper, an innovative approach is presented to control and predict the best advancement direction. MATLAB software is the framework of the presented model. The designer can find the desired direction by introducing a start and end points for caving propagation. Finally, its output can be used as input to scheduling programs of caving mines. Application and comparison of the model based on the advancement direction algorithms are validated using 98 using over 12 periods. The results show that the presented model respected to advancement direction and the model size is an accepted range for production planning problems.

Predicting the ampere consumption in carbonate rock sawing process is very important for the determination of the electrical energy cost per unit of production. In addition, ampere consumption prediction may be used for selecting the optimum operation parameters to obtain high production rate. In this study, it is aimed to develop fuzzy classification systems to evaluate and classify the carbonate rock based on physical and mechanical properties such as Brazilian tensile strength, equal quartz content, grain size, uniaxial compressive strength, Young modulus and Mohs hardness. Varieties of seven carbonate rocks such as Azarshahr travertine, Hajiabad travertine, Dare-bukhari travertine, Harsin marble, Salsali marble, Anarak marble and Haftooman marble were classified by developed fuzzy classification system. To validate the classification’s results, ampere consumption was recorded during sawing process for each studied rocks. The results of the study show that the three-class fuzzy classification system is capable to evaluate the carbonate rock saw-ability and ampere consumption during soft dimensional stone sawing process.

The dimension of underground structure is a key factor in its stability. Rock blotting has important effect in rock mechanic projects. It increases the stability of rock blocks. The performance of rock bolt is depending on the quality of its set up. Quality of its set up is determined by pull out test method. Numerical simulation is other method for determination of rock blotting behavior. In this paper, the effect of tensile loading on the “Y” shape joint is determined using FRANC2D. The angularity of large joint tail (β) changes from 0° to 90° with increment of 45°. The angularity of small joint tail related to large joint tail (α) changes from 20° to 160° with increment of 20°. The spacing between joint and loading place change from 2a to 4a with increment of “a” which “a” is the length of large joint tail. Totally 52 model were simulated. In the case of horizontal joint the crack growth length is maximum and vertical joint has minimum effect on the crack growth. When the angularity of large joint tail related to horizontal was 45°, the maximum of crack growth was occurred. The maximum of crack growth from small joint tail was occurred when it is in horizontal configuration. The maximum number of small joint tail growth occurred when its angularities related to horizontal axis was 45°.

Changing excavation from drilling and blasting to mechanical method has many advantges related to the environmental health, safety, and economic benefits. The rock mass weakness degree due to the possibility of excavation by a bulldozer can be the important basis for the changing the excavation method. In adition, the cost price of each method is also an important criterion. The rock mass weakness degree can be investigated using rock mass properties such as uniaxial compressive strength (UCS) and discontinuity spacing or relatively lower limit of blastability index (BI) or at the higher limit of rock fragmentation index (RFI). UCS=13.38 MPa, discontinuity spacing<0.1 m, BI=20.33 and RFI=42 were obtained in Sardar Bucan limestone mine. The powder factors were also obtained 0.18 kg/m3 and 0.253 kg/m3 for using BI and RFI respectively. Drilling and blasting operations were carried out for using different powder factors espacialy for minimum powder factor of 0.253 kg/m3 with burden to blasthole diameter ratio of 42 corresponding RFI=42. The cost price was assessed 14434 Rls/ m3 (6443 Rls/ton) for powder factor of 0.253 kg/m3. Mechanical excavation using a bulldozer was applied to replace the method of drilling and blasting, and the cost price of excavation by bulldozer was obtained equal to 8319 Rls/m3 (3713 Rls/ton), which was 58% of the cost of drilling and blasting method at the optimized conditions. The possibility of changing excavation from blasting to mechanical method can be an important development in the safety, economic and environmental benefits.

The effects of atmospheric pressure of the site of installation of a centrifugal two-stage heavy medium separator is of crucial importance because the pressure difference between the medium input and the sink output streams is adjusted by the back pressure rings. However, contrary to the dense medium cyclone, the raw feed ore into this separator is sluiced without pumping.  In this research, the effect of atmospheric pressure on the flow pattern inside the Tri-Flo separator is investigated using the computaional fluid dynamic (CFD) simulation. Therefore, the volume of fluid (VOF) model and discrete phase model (DPM) were used for the calculation of the diameter of the air core and the behavior of solid particles, respectively. Reynols stress model (RSM) was used for turbulence modeling. Simulations were performed in three different atmospheric pressure including 1, 0.86 and 0.64 atm, representing the site of installation at sea level and heights of 1250 meters and 3500 meters above the sea level, respectively. The CFD simulation results showed that the change in atmospheric pressure has some effects on the flow fields, macroscopic parameters and the performance of the Tri-Flo separator. The results of simulation were validated against the experimental data achived using the transparent laboratort Tri-Flo separator. The fluid velocity in output streams and the size and the pattern of air core were used for validation. The decrease in Ecart propale error (Ep) of the separator and increase in the medium recovery were observed, when the atmospheric pressure was decreased. However, the effects were in the margin of 2%. According to the results of this research, the Tri-Flo separator can be used in different elevations from the sea level, without serious problem in the operation regime.

The present study aims to evaluate the effects of fracture mechanism on physical parameters such as size, shape, and specific surface area and to provide a description on how the grinding mechanisms of ball mill and High-Pressure Grinding Roll (HPRG) work. Moreover, the effects of these parameters on qualitative indicators of green pellets were also investigated. Furthermore, the amount of fine particle and surface shape of the obtained particles were compared. Results showed that the specific surface area of particles produced through HPGR is more than Ball Mill. This feature was recognized as the result of the increasing fine particles in the range of 7-25 µm and the presence of micro and macro cracks and fractures on the surface of the most particles manufactured by HPGR. In addition, pelletizing processes of HPGR and ball mill products at the same particle size distribution of 80% less than 43 and 90 µm showed that green pellets produced with HPGR product in d80=90 µm have more drop number and compressive strength in both dry (D.C.S) and wet (W.C.S) modes compared to ball mill. Also, the green pellets produced from HPGR product at d80=43 µm had higher drop number and W.C.S than ball mill product. But, compressive strength of green pellets in HPGR product showed 63.18% lower values of D.C.S than pellets produced by ball mill product at d80=43 µm. The reason for the lower D.C.S of the HPGR product is the increase of fine particles and specific surface area that consequently led to high water absorption by the fine particles.