نشریه مهندسی منابع معدنی
سال سوم شماره 4 (زمستان 1397)

The Common Diffraction Surface (CDS) stack method has been introduced to solve the conflicting dip by merging the concepts of Common Reflection Surface (CRS) stack method and dip moveout (DMO). This method considers a continuous range of operators in pre-stack data set to simulate a Zero-Offset (ZO) sample which handle the conflicting dip problem in to full extent. However this method still contains artificial events and noise to the ZO stack section. As the coherence of each operator is available before stacking it is proposed to use this coherence as criterion for acceptance or rejection an operator for the stack. In this way the operators are not coherence with any seismic events will be illuminated. The results of this research shows by implementing the proposed method not only it is possible to solve the conflicting dip in to full extent but also the signal to noise ratio will be increased.

Determination of the ultimate pit limit is one of the most important design in open pit mining. In the present methods, the final pit is determined based on the maximization of undiscounted profit. For this purpose, various mathematical, heuristic and meta- heuristic algorithms have been developed. Among these methods the most used one is the Lerchs-Grossman (LG) algorithm. It has been mentioned that it is better to design the ultimate pit based on the maximization of the net present value. In other words, the optimal arrangement of blocks and the final pit outline must be determined simultaneously. For that reason, in this paper the binary and nonlinear mathematical model of this problem and some suggestions for its linearization have been presented. In addition, in order to reduce the number of decision variables the concepts of the earliest and the latest possible time for extracting a block have been defined. In the following, with the use of downward cone and positional weight and the earliest extraction time of ore blocks, two heuristic algorithms have been developed for simultaneous determination of the final pit and blocks extraction sequence. At the end the results of these algorithms have been compared with the LG algorithm. The results show that these algorithms are capable to produce good result.

Lorestan province with 21.5% of the country's decorative stones reserves has abundant capacities and abilities in the rock industry, but has poor performance in the field of mining, processing and sale, which has led to a decent position in global and even domestic markets. Not have Therefore, the present study aimed to investigate the barriers to success in the Lorestan rock industry. The statistical population of the study was the owners and owners of active units of Lorestan rostrum. 160 people were selected using census method to respond. The data gathering tool was a closed-answer questionnaire which was used to measure the reliability of its variables using Cronbach's alpha. Using a structural equation modeling technique,while investigating the barriers to the success of the stone industry, a reliable model for predicting the barriers to the success of the stone industry was presented. It turned out The findings showed that the weakness in packaging (r = 0.11), lack of government support (r = 0.11), lack of expertise and technical knowledge (r = 0.07), along with crude (r = 0.04) The direct and significant effects, and the weaknesses in planning (r = 0.001) and the traditional management (r = 0.008), the indirect effect (through crude) on the obstacles to the success of the stone industry. Therefore, the final model resulting from the above variables has explained 39% of the variance of the barriers to the success of this industry.

In the recent decades, the study of rock brittleness in infrastructure projects were addressed by different researchers. Unfortunately, up to now, a universally accepted definition for rock brittleness had not been presented. Furthermore, due to lack of equipment as well as complexity and time consuming of the preparation and testing procedures in the proposed methods of direct measuring of rock brittleness, most of researches were carried out on the basis of indirect indices. Suggested brittleness Indices can be categorized according to the parameters which were used in developing these indices. One of the most important Brittleness Indices which has been widely used in various rock mechanic project is strength based brittleness index. The main objective of this study is to provide a new index based on uniaxial compressive and tensile strength for evaluating the rock brittleness. For this purpose, firstly, by reviewing the existing strength based indices for evaluating rock brittleness, a general equation was suggested for the new index. Then, by using statistical and probabilistic analysis on the obtained results for rock brittleness in punch penetration test, the coefficients of suggested index were calculated. According to the results, the values of 0.807 and 0.4458 were proposed for uniaxial compressive strength and tensile strength coefficients, respectively. Using the suggested index, it is possible to predict the rock brittleness with the value of R2 equal to 0.878.

Rocks are usually exposed to freeze-thaw and/or heating-cooling conditions in many environments. In this research, sandstone specimens of Lushan area were used and investigated the impact of number of freeze-thaw cycles and the effect of temperature in the heating-cooling process on sandstone permeability. The freezing temperature of -16°C was considered to study the effect of number of cycles. In this state, the tests were carried out on the specimens withstood 1, 5, 10, and 20 freeze-thaw cycles. To study the effect of heating-cooling, the tests were conducted on the specimens that withstood one heating-cooling cycle. The specimens withstood temperatures of 60, 100, 200, 400, 600, 800, and 1000 °C at the heating process and then cooled in the laboratory environment. Results indicated that permeability rate reduced after one cycle of freeze-thaw cycles the reduction continued to 5 cycles. Permeability increased slightly in 10 cycles and the increase was significant in 20 cycles. Sandstone permeability reduced up to 100 °C and then increased with the temperature increasing at the heating-cooling process. Permeability changes in the heating-cooling process were consistent with the variations of velocity of longitudinal waves, dry unit weight, and effective porosity.

The particle size distribution plays an important role in the flotation due to the impact on the bubble-particle collision, attachment, and detachment. In the mechanical flotation cells, fine particles (generally smaller than 38 microns) have less collision performance and coarse particles (generally larger than 75 microns) have less attachment performance. High turbulence caused a detachment of the particles from the bubbles and thus reduce the performance of the attachment. In the rougher stages of flotation of sulfide minerals, particles size is the most effective parameter. In the flotation, the most loses of valuable particles are in the very fine and very coarse particles. In this research in order to improve the zinc recovery in the flotation circuit of the Bama lead and zinc company, reagent distribution regimen was improved. Therefore, in the laboratory scale, using a design experiment (Taguchi L9), different reagent distribution regimens were compared. The results showed that the adding of 30 g/t of collector (AERO3477) in the rougher stage, along with 15 g/t of Potassium Emyl Xanthate (collector) and 7 g/t of MIBC as frother in the scavenger cells was increased the recovery of fine and coarse particles about 3.2 and 5.4 %, respectively. Finally, based on the laboratory results (Taguchi L9), the reagent distribution regimen in the zinc flotation circuit of the Bama plant was modified. After modifications, the zinc recovery in the fine and coarse particles was increased about 2.5 and 3.9 % respectively. Also the zinc assay of final concentrate was increased about 4.1%.

Production of lightweight aggregate is usually done by different clayey materials. Some kinds of wastes can be utilized in its production. In this research wastes of Zarand coal processing plant was added with the following percent 1, 2, 3, 4, 5, 6, 7, 8, 10, 15 and 20 to the raw material of Omranpars lightweight aggregate production plant and burned at 1140˚C for 5 minutes. Density, compressive strength and water absorption of produced samples were analyzed. FE- SEM images of some samples were taken for further studies. Results show that the optimum percentage of Coal waste addition is 3% which was tested between 1110°C to1160°C to find the optimum burning temperature. The optimum temperature was between 1140°C to 1150°C. At this temperature and coal waste addition percentage density was 265kg/m3, water absorption was 15.2% and compressive strength was 0.8 MPa.

In this paper, the removal of iron oxide (Fe2O3) through scrubbing process has been investigated which applying in the glass industrial. The iron oxide was obtained from silica sand samples of Cheshun mine. Chemical elements were analyzed by Atomic Absorption Spectroscopy (AAS). Scrubbing by sulphuric acid was applied in order to remove iron oxide from silica sand. In addition, the study of parameters affecting the process was carried out through designing experiments by Taguchi method in Minitab. The AAS results showed 96.23% of SiO2, 0.13% Fe2O3, and 1.67% Al2O3. Mineralogical studies of silica sand showed that there have been hematite, goethite, and limonite which are the most important iron oxide minerals. The results of scrubbing indicated that the iron removal has increased by decreasing pH from 2 to 1. Also, the amount of iron in silica sand reduced by increasing the solid content from 50% to 70% and temperature degree from 400 to 800. The highest iron removal rate was obtained under the optimum condition including pH=1, temperature degree=80C0, and the solid content of 70%. Therefore, the final processed sample contained 0.031% iron oxide (Fe2O3) which is suitable for producing cup glass, glassware, and borosilicate crystal.