سایش

The first production cycle in open-pit mines is the drilling of blast holes, which is a major part of the exploitation costs. Bits are considered as one of the most important parts of drilling in operational processes due to the type of application and high costs. Examining the parameters affecting the bits wear can reduce the effect of wear, prevent wasting time and additional costs of the drilling process. Therefore, in this study, first, by determining the effective parameters based on the results of univariate regression and Principal Component Analysis (PCA), the relationship between these factors and the tricone rotary bits wear has been determined through statistical methods. Then, 100 linear and nonlinear models were examined to predict the rate of the tricone rotary bits wears during drilling, of which only 21 models, including 6 linear models and 15 nonlinear models, were approved. The performance of these models is evaluated based on the root mean square error (RMSE), coefficient of determination (R2), Variance accounted for (VAF), and mean absolute percentage error (MAPE). then the priority of each method is determined based on performance evaluation and prioritization strategies. In this research, three strategies of prioritization, the Rank average method, the Borda method, the Copeland method, and finally the Aggregate of these methods have been used. The ranking results show that the best model for predicting the tricone rotary bits wear is the regression model with independent variables of Weight on Bits (WOB), Uniaxial Compressive Strength (UCS), and Geological Strength Index (GSI). According to the results of sensitivity analysis, the Rij value of the Weight on Bits (WOB) is 0.982, which is more than the other two parameters of the final model. Therefore, this parameter has the greatest effect on the tricone rotary bits wear and it is the most important parameter of the final model.

Extraction and exploitation is one of the important parts in the field of mines and mining industries. Blast hole drilling is the first stage of the production cycle in open pit mines. Which account for a large part of the exploitation costs. In operational processes, bits are one of the most sensitive and important parts of drilling, due to the type of application and high costs. Wear of these tools are an important parameter for estimating the efficiency of drilling equipment in mining projects. Wear of drilling bits is a function of various factors, some of which are related to machinery, operational parameters and management parameters, and some are dependent on the conditions and rock properties and rock mass and the surrounding environment. Examining the parameters affecting the tricone rotary bits wear can prevent wasting time and additional costs of the drilling process. Therefore, in this study, the evaluation of the factors affecting the tricone rotary bits wear in Sarcheshmeh copper mine has been investigated. For this purpose, the tricone rotary bits wear has been calculated through weight loss and by determining the effective parameters, the relationship between these factors and the tricone rotary bits wear has been determined through statistical methods. Then, using sensitivity analysis, the effect of input parameters on the target is determined. The results of these analyzes show that all the parameters of the study except the Chemical Index of Alteration (CIA), porosity and Equivalent Quartz Content on the desired output (the tricone rotary bits wear).

The research project in this study is a part of a 36 kilometer tunnel with 6.32 m in diameter for conveyance of water from the western of Zagros to the Uromia Lake that is under construction through hard rock by using of two tunnel boring machines. Lithology of the tunnel alignment including of granite, granodiorite, hornfels, schist, limestone, dolomite, shale, slate and phyllite. The wear of cutting tools is one of the main challenges of the studied tunnel, which impact significant cost and serious delays on schedule. Wear can be defined as the continuous and unwanted loss and removal of material from the surface of a solid object, as e result of mechanical actions, such as contact and relative motion between two objects. Abrasive wear and impact wear are one of the most important type of wear occurs on the TBM disc cutters. In this paper field actual cutter wear data belong to 9.5 Km of the bored tunnel, geotechnical properties and laboratory information are used to study the wear phenomena. Field data show that abnormal wear of disc cutters with 51 percent is more than normal wear. Also the study of disc cutter consumption rate in relation the geological characteristics and TBM parameters show that the Cerchar abrasivity index (CAI) and uniaxial compressive strength (UCS) are in agreement with disc cutter consumption rate. The obtained results indicate that thrust, torque and penetration rate have a relatively good relation with disc cutter consumption rate. It was not found any relation between rock mass quality index, geological strength index and disc cutter wear rate. In general the relative cutter life in the studied tunnel is in accordance with the relation proposed after Bruland (1998).

Currently, in mineral processing plants most often high throughput SAG mills are used in comminution circuits. Since shut down of these units could result in production stoppage, the availability time of these equipment are of prime importance. One of the main parameters involved in shut down time is the liner replacement time. Hence, models which are able to predict liner life time could have a significant effect on the performance of the operation. In the past decades, various models have been proposed to estimate the liner wear rate, but due to their empirical nature they could only be used in a certain operating conditions. In this research, a phenomenological model which could predict the liner wear rate considering parameters such as operating conditions, liner hardness, pressure on the lifter, relative velocity of particles and mill shell was proposed and tested. Availability to industrially measured liner profiles data during the liner life time at the Sarcheshmeh and Gol-E-Ghohar SAG mills provided a solid base to calibrate and validate the model. The results showed that the model predictions and the actual measurements of the liner wear rate of SAG mills correlate well at Sarcheshmeh (R2=0.94) and Gol-E-Ghohar (R2=0.97) concentrators.