جواد ضیایی

Generally, mine haulage operation is taken into account as one of the substantial links in the value chain of mineral production. Indeed, the haulage operation consists of about fifty percent of the operating costs in open-pit mines. Therefore, a comprehensive model should be developed for evaluating haulage operation considering principal indicators. Since there are various qualitative and quantitative factors affecting the haulage equipment selection, it is essential to develop a holistic and novel approach for the decision-making process. In this study, a multi-criteria decision-making (MCDM)-based simulation is proposed for haulage equipment selection, which is a two-step approach. In the first step, an integrated approach is developed based on fuzzy and rough set theories. In the second step, a discrete-event simulation is established for characterizing the haulage operation system. Thus, the optimal size and number of equipment are specified by evaluating several what-if scenarios. Zaghdare Copper Mine is considered as a case study for assessing the performance of the proposed algorithm. The results of the multi-criteria decision-making process revealed that the hydraulic excavator-truck system is associated with the best haulage system in this mine. A discrete-event simulation is developed for configuring and analyzing the selected haulage system. Different what-if scenarios were developed based on changing haulage distances and equipment availability. Consequently, the optimal number of trucks was computed for each scenario. The results revealed that an increase in the availability of the equipment (from 80 to 90%) leads to the reduction of the number of the required trucks.

One of the most crucial factors involved in the optimum design and cost estimation of rock sawing process is the rock abrasivity that could result in a significant cost increase. Various methods including direct and indirect tests have been introduced in order to measure rock abrasivity. The Schimazek’s F-abrasiveness factor ( ) is one of the most common indices to assess rock abrasivity.  is the function of three rock parameters including the Brazilian tensile strength ( ), median grain size ( ), and equivalent quartz content ( ). By considering its formulation, it has been revealed that the coefficient of each parameter is equal, which is not correct because each parameter plays a different role in the rock abrasion process. This work aims to modify the original form of  by introducing three correction factors. To calculate these correction factors, an integrated method based on a combination of the statistical analysis and probabilistic simulation is applied to a dataset of 15 different andesite rocks. Based on the results obtained, the values of -0.36, 0.3, and -0.89 are suggested as the correction factors of ,  and , respectively. The performance of the modified Schimazek’s F-abrasiveness factor ( ) is checked not only by the wear rate of diamond wire but also by the cutting rate of the wire sawing process of Andesite rocks. The results obtained indicate that the wear rate and cutting rate of andesite rocks can be reliably predicted using . However, it should be noted that this work is a preliminary one on the limited rock types and further studies are required by incorporating different rock types.