نشریه روش های تحلیلی و عددی مهندسی معدن
پیاپی 21 (زمستان 1398)

There are two approaches for measuring hydrocarbon saturation; well log interpretation and usual developed formulas. Archie’s equation is one of the most fundamental equations for water saturation calculation. Archie’s equation includes three factors Cementation factor, tortuosity and saturation exponent. Archie determines those factors based on lab results in sandstone and provides fixed value for them. Carbonate reservoirs have variety of texture, shape and distribution of pores, therefore mentioned factors, especially cementation are not considered constant. Several methods are presented for calculation of cementation factor continuously. In none of these methods, the Change in the lithology type and conversion of limestone to dolomite is not considered. In this study the relation between cementation factor and density log was examined. Because cementation factor can be defined as a parameter that have a close relation with density. By calculating matrix density and accordance factor between matrix density and cementation factor from core’s analysis, the log will be generated that estimate the variation of cementation factor around the borehole. The regression of calculated values with the core data is 84.09 percent, that shows this method is useable for calculation the cementation factor in carbonate rock.

SummaryTerrorist attacks could cause serious destruction and death by damaging to buildings and infrastructures. One of the most vulnerable mine structures are storages containing explosives, detonator caps and Detonation fuse. In this study a 6.5 x 2.5 storage of electrical caps is designed by ETABS firstly. Then its wall is modeled in finite element commercial software ABAQUS in order to investigate its behavior and resistance under blast loads. The U-shaped shear wall type with dimensions of 3x3 meter is chosen for this wall, and the wall is considered in 4 conditions: with 8, 10 and 15 cm protective shield and without protective shield. Blast loads are positioned in 10, 50 and 100cm distance of center of the shield. The results show that in the existence of the shear wall, displacements of the shear wall, shear stress of the wall and stress at the base of the column decreases up to 97.4%, 56.4% and 36.7% respectively. It’s concluded that reinforcement of shear walls with protective shields provides sturdy structures in order to store explosives and detonator caps in mines.IntroductionIf an explosion takes place outside of these detonator caps and detonation fuses, the of the blast wave effect could cause a blast at explosives inside the storage and lead to a great damage. Hence, it’s important to study these effects on this kind of structures. In this study, a 3.5x6.5 storage of electrical cap, whose walls are designed as U-type shear walls protected by concrete shield. In order to investigation behavior of the wall and the effectiveness of the shield against blast loads, a wall with dimensions of 3x3 is modeled in ABAQUS under 4 distinct conditions: with various 8, 10 and 15 cm shield and without shield. Methodology and ApproachesTo design the walls, the software ETABS is used, and finite element commercial software ABAQUS, which has great ability to solve explicit dynamic problems, is employed to simulate the behavior of walls and shields under blast loads. Results and ConclusionsBy protecting the wall against blast loads, Concrete shield was able to reduce the displacement of the wall, stress of the wall and stress at the base of the column up to 97.4%, 56.4 and 36.7 respectively. Besides, it keeps explosives and detonator caps inside the storage safe by degrading the energy of the outside blast wave.

The block extraction sequence is among the most challenging and important issues that should be regarded through whole mining operations to reach the maximum profit amount. Such Open-pit Production Scheduling problems can be solved under either deterministic or non-deterministic states. This study aims to model the problem applying robust counterpart linear optimization which uses the box set based counterpart. Block economic value, as the objective function coefficient and operational capacity, as the constraints coefficients, are considered as uncertainty sources. Exact mathematical modeling using CPLEX solver, is applied to solve the box counterpart. The model, which was solved in deterministic and uncertain conditions, terminated in results with some differences in scheduled plans.

Evaluation of zone dispersed mineralization from blind mineralization in active and inactive mines are the main challenges in mining geochemistry. In this research a new model has been presented for detection of anomaly by integration of singularity and zonality methods. This method show the depletion and enrichment of vertical zonality index in study area. Singularity of vertical zonality index was mapped in Kerver2. Results show west of this area is blind mineralization.

Thickeners are the key units in the hydrometallurgical processing operations and used to separate solids from liquids. In this research, the pattern of mixture of the pulp and clear water phases in a mixing duct known as E-DUC was calculated through CFD, and the effect of flow rate changes and solids content of the input feed on dilution before the feed well was studied. Fluid dynamics were studied by modeling continuity and Navier-Stokes equations in Fluent version 14.5. The k-ε library function was used to apply turbulent flow conditions and the mixture model was used to study multiphase flows. The flow rate and solids content of the feed under the factory’s operational conditions were 605.45 m3/h and 25%, respectively. In this study, dilution of the feed flowing into the feed well was calculated to be 19.51 using simulations under operational conditions, which was an acceptable estimate of the existing dilution. Afterwards, by changing the flow rate of the feed, the effect of this parameter on dilution of the pulp input to the feed well was determined. By increasing the flow rate to 700 m3/h dilution levels rose to 28.5 respectively.

Fine particles of pyrite are not recovered completely by magnetic separators in presence of iron ores such as magnetite and hematite. Reverse flotation is an effective method to reduce sulfur from magnetic separators concentrate. The aim of this study is to investigate the effect of operational variables on flotation column performance in desulphurization process from iron concentrate and to optimize operational conditions for the sake of achieving the maximum sulfur recovery with the minimum iron waste. To do so, by conducting 45 tests, based on a central composite design (CCD), the effect of important operational factors including gas flow rate, froth depth, slurry solids percent, frother/collector dosage and pH was considered. The iron ore sample was collected from magnetic separators concentrate stream of Gole Gohar iron ore complex with d80 equal to 90µm. Sulfur and total Fe contents of the sample were found to be 0.48% and 63.3%, respectively. Optimized operational conditions were predicted to obtain the minimum and maximum values for concentrate and tailing sulfur grades respectively via the use of significant factors and variance analysis. Based on the results of ANOVA, the optimum values of column operation parameters were 150 gr/t of PAX, 200 gr/t of MIBC, 20 cm froth depth, 1.6 cm/s of air flow rate, pH of 4.9 and a solid concentration of 30%. By applying operational optimum conditions, concentrate sulfur grade at significant level of 95%, tailing sulfur grade and iron recovery were equal to 0.08%, 34% and 98%, respectively.

SummaryThe Module Index (MI = Al2O3/SiO2) is a criterion for determining the ore quality in bauxite deposits. Despite of wide use of the MI, it can not provide reliable criteria for determining of the ore quality due to less statistical attention to outlier data. In this paper, we have introduced the Bauxite Quality Index (BQI) as a new criterion for determining of the bauxite ore quality. We used geochemical data of the Jajarm bauxite deposit to evaluate the ability of the mentioned index. The BQI could be able to classify the ore zones based on the ore quality and economic importance. The BQI would be control the outlier data and reveal relationship between the variables, which are the most important characteristics of this index.IntroductionBauxite is the most important source of aluminum. The quality of bauxite ore depends on mineral composition of the ore which has been calculated by the Module index (Al2O3/SiO2 ). This paper introduced more comprehensive bauxite quality index (BQI) than the MI, using multivariate statistical analysis. We apply geochemical data of the Jajarm bauxite deposit to evaluate the ability of the BQI. Methodology and ApproachesThe BQI is determined based on factor analysis of geochemical data of the Jajarm bauxite deposit. We investigate the relationships between ore quality and alumina-silica contents using the MI and BQI. Then, the economic potential of the ore zones is evaluated by either MI and BQI. Finally, the correlation coefficients of the different parameters are calculated, and the all obtained results are compared and discussed. Results and ConclusionsThe Bauxite Quality Index (BQI) is a new suggested criterion for determination of bauxite ore quality. This criterion reveals hidden relationships of Al2O3 and SiO2 with other variables and outlier data. Comparison of the MI and the BQI indicates that the BQI is more reliable than the MI in recognition of the high grade ore bodies. x.