فصلنامه مهندسی معدن
پیاپی 46 (بهار 1399)

Rock cuttability always has been recognized as one of the most effective parameters in selection and design of cutting tools and prediction performance of mechanical excavator machines. Field, experimental and theoretical methods have been applied into determination of rock cuttability. In this study, the theoretical model of rock cutting forces estimation presented for V-shape disc cutters was modified taking into account the influence of cutter edge radius. In order to validate the proposed model, full-scale rock cutting test data presented by Balci and Tumac (2012) and t-test with 99% interval confidence have been implemented. The results showed that there is a strong correlation between estimated rock cutting forces and real data, and since the p-value is more than α=0.01, both methods have the same values on average. To study the effect of edge radius of V-shape disc cutters, the proposed model was used. The results showed that for a constant edge angle, increasing edge radius increases cutting forces of blunt disc cutter more than those of sharp disc cutter. Also, with increase in penetration depth, the effect of edge radius on cutting forces diminishes in such a way that the cutting forces approach those of sharp disc cutter. In other hands, increasing edge angle caused a non-linear increase in blunt disc cutter cutting forces for a constant penetration depth.

The primary grinding of the concentration plant No.1 at the Sarcheshmeh copper complex includes eight ball mills working in a closed circuit with hydrocyclones. Due to the importance of the density of hydrocyclones in the classification process, the overflow density control loop was included in the initial plant design. Because of high cost, additional maintenance efforts, safety issues and constraints of nuclear density meters, this control loop never became operational. In this research, the percent solids was determined based on the mass balance equations in a format of a soft sensor. These sensors are computer programs that are used as an inexpensive alternative to hardware sensors and their use has increased in the material processing industry in the recent years. After transferring of the measured data to the control room, a program based on mass balances of solid and water the calculations for all 8 ball mills was prepared. To start the overflow density control loop, a control valve was installed on the inlet of the hydrocyclones feed tank. With the installation of hardware and the use of a soft sensor, the hydrocyclones overflow density control loop made operational for one of the ball mills. The monitoring of the circuit showed that the percent solids fluctuation of hydrocyclones overflow decreased from the range of 30.4 ± 4.5 when the percentage of solids was not displayed to a range of 28 ± 0.5 when using the percent solids control loop was operational. Furthermore, the measurement of the size distribution indicated that the percent of material finer than 75 microns of the overflow increased from 63.5% to 67% on account of installation of the control loop.

Dewatering and water recycling operations in mineral concentration processes lead to not only cost-effective water use, but also less waste disposal to the environment. In this study, optimization of dewatering process in Zareshouran gold processing plant is carried out using hydrocyclone containing circuit. For this purpose, 12 experiments using 4 spigots with 2, 3, 6, 9 mm diameter, and in 3 operation state of spray discharge, transition state and rope discharge have been conducted. Dewatering capability of hydrocyclone is evaluated based on solid weight percent and solid recovery of underflow stream. The results indicate that in the same operation state, increase in spigot diameter leads to an increase in solid recovery and a decrease in solid weight percent of underflow stream. On the other hand, as the operation state tends to rope discharge solid weight percent and solid recovery of underflow increases simultaneously. Therefore, it can be stated that spray discharge pattern has a higher dewatering capability. Using a spigot with 6mm diameter in the operation state of spray discharge, solid recovery and solid weight percent reaches 75 and 61%, respectively. In this condition, if hydrocyclone is considered as the first step of dewatering process, 75% of the feed solid content can be directly transferred to tailings dam at a lower cost. On the other hand, the overflow stream carries only 25% of feed solid content. If pressure filter present in current dewatering system are considered as the second step of dewatering process, their feed slurry will be reduced by 75%. This means an overall increase in dewatering system capacity by hydrocyclone.

In this research, a rule-based expert system, with a graphical user interface, has been designed and implemented to measure, evaluate and provide a policy of improving mining productivity corresponding to the productivity management cycle. The expert system includes a set of rules related to how to calculate and analyze the productivity gap, and the inference engine is based on the analysis of the leading rules. Major policies are being improved based on quantitative and qualitative indicators. In order to evaluate the effective variables and to determine the relative importance of these policies, a fuzzy inference system based on expert opinions has also been implemented. To evaluate system performance, data from a gold mining complex was used for a period of eight years, and various indicators were developed in technical, financial, human resources and markets. For undesirable growth indicators, seven improvement policies were presented, with the highest and lowest share being related to the policy of "improving the production process" and "human resource management." Based on the evaluation of 40 qualitative components, 21 cases were in a rapid recovery situation. Also, after implementing the fuzzy inference system, the policy of "reducing energy consumption" with the importance of 56% was the most important.

Mining operations and waste resulting from it can be considered as one of the most important sources of hazardous elements in the environment. Identification of the spatial distribution of toxic elements in the mine waste dump systems requires the assessment of environmental hazards and strategies. To achieve the goal, the sampling was conducted on a waste dump located in the east of Angouran mine at an area of 300,000 square meters. For this purpose, 38 soil samples were selected for study and modeling. Statistical studies of the data set for As, Cd, Cu and Co elements were performed. In addition, Q-Q plot was used to remove outlier from the data, which resulted in an increase in the correlation coefficient of the results. In the next step, statistical analyses were performed to determine variogram parameters for the studied elements and the distribution of toxic elements was modeled on the basis of sequential Gaussian simulation (SGS) method, which results in high concentrations As in the south, west, and north of the dump. Elevated concentration of Cd can be seen in the southwest and northeast parts of the dump. Also, high concentrations of Co and Cu accumulate in the western, southern and northern parts of the dump. In order to validate variograms, cross-validation method was employed which is a fundamental method for comparing the effect of different variogram models and simulation methods on interpolation results. Correlation coefficients for As, Cd, Cu and Co elements were 0.885, 0.8056, 0.6867 and 0.9792, which represent the validity of simulation results.

Underground mine ventilation networks are affected by various parameters which have not been seen at the planning phase. The efficiency of ventilation network is related to this parameter. In this research, resistance variation is defined as one of the parameters involved in ventilation performance. Uncertainty of resistance variation in ventilation networks during mine life was modeled by sensitivity analysis method. For this goal, limited differential gradient of flow alteration against variation of resistance was calculated for each branch. The proposed method was implemented for the TAKHT mine ventilation network. Changes of resistance at main tunnel responsible for the transportation of persons and extracted materials were considered as inputs of the sensitivity analysis model. The maximum amounts of limited differential gradient are related to the most sensitive branches against resistant variation in the main tunnel. They are an air outflow tunnel and a ventilation duct. High-sensitivity branches have a higher risk for failure in the ventilation system, so the sensitivity of each branch can be considered as a factor in the reliability analysis model.

Exploration of the new mineral deposits around the existing mines is an important objective in mining industry. Using multispectral remote sensing images, due to their diversity and vast availability is a useful tool to meet this purpose. In this research, the Zonouz region was investigated for discovering new high potential kaolinite mineralization areas using Landsat8 and ASTER data. Zonouz kaolin mine which is located in Marand county, East-Azarbaijan, is the biggest kaolin deposit in the Middle-East. In the current research, the capability of Landsat8, as a new generation multispectral data, and ASTER data were examined in mineral detection. At first, the preprocessing of data, i.e. atmospheric and topographic corrections and elimination of the vegetation cover were carried out. Then, the spectral profiles of the endmembers of the study area datasets were extracted. Identification of the extracted endmembers was done by comparison of the unknown spectra with reference spectra of the USGS spectral library, and 3 minerals including kaolinite, quartz, and Fe-bearing minerals were identified. Finally, the distribution maps of the identified minerals were extracted by using of the artificial neural networks, as a non-linear supervised method. To the best of our knowledge, the applied neural networks structure has not been implemented on LANDSAT 8 and ASTER data earlier. This research is also the first implementation of LANDSAT 8 and ASTER data in Zonouz kaolin region for extension mapping of the kaolin. Two different approaches including virtual verification and field sampling were applied for validation of the results. According to the Findings of this research, both of ASTER and Landsat8 datasets proved successfulness for identifying the kaolinite; but the Landsat 8 data exhibited better performance in detecting and mapping of the quartz and hematite. Finally, 6 promising areas were determined as high potential zones of kaolinite mineralization for future studies.