The mining industry plays a significant role in the extraction and processing of various ore materials (phosphate, copper, iron, gold, aggregates and others), contributing to industrial and economic development. Rock fragmentation is a fundamental operation and a complex element in mining activities influenced by multiple parameters, including geological and geometric factors, explosive load parameters, and others related to the details of the execution of the blasting plan. The effectiveness of blasting depends on factors such as the geological structure, volume, optimal size of rocks to be blasted, and compliance with safety conditions. To achieve desirable outcomes, it is crucial to make informed decisions regarding the types and quantities of explosives to be used, along with other principal parameters of drilling-blasting design. Continuous evaluation of rock fragmentation is essential for optimizing blasting plans by contributing to the improvement of the quality-price ratio under favorable environmental and safety conditions. This study aims to analyze and enhance the quality of rock fragmentation resulting from blasting activities in the Kef Lahmar-Setif limestone quarry (northeast Algeria), which is characterized by significant rock mass fracturing. This fracturing will be carefully analyzed in order to arrive at an accurate blasting plan for the structure of the studied rock massif. As the aim of the research is to optimize the blasting plan to generate maximum gas pressure and minimize shock pressure due to the existing fractures in the rock mass. in order to test this hypothesis, we conducted several blasting tests by modifying the charge rate of the explosives used (Anfomil and Marmanite III), while maintaining the same parameters in the blasting plan for each test. The goal was to achieve optimal fragmentation. The particle size of the blasted rock pile was analyzed using WipFrag software, which utilizes image analysis techniques.
Underground mining operations are a very problematic task, especially in poor geotechnical conditions. The right choice of excavation and support techniques leads to adequate and secure mining operations. This should ensure the overall stability of the underground mine with the best productivity and stability performance. In this paper, an empirical model for obtaining support systems for underground galleries was applied. Then, a numerical model for the evaluation of the performance of support measures for rock masses in the Boukhadra iron mine was introduced. Extensive field and laboratory tests were performed to obtain geological, geotechnical, and mechanical data on the entire geologic formations of the (1105 m) level. The performance of the design is supported by the selection of a common support plan between RMR, Q, and UBC systems for each geotechnical unit. Therefore, the rock masses classification based on the geo-mechanical model has determined the suitable support systems. The finite element model (FEM) was used for the analysis of rock mass behaviour, displacements, stress, and plastic point distribution. The results permit the optimization of the plastic zone thickness around the gallery. The outcomes of this study could improve the stability of the mine by choosing the right direction of excavation in consideration to the direction of the discontinuity planes. In order to choose between the current and the recommended mining operations, an equivalent calculation sequence was verified. Our study demonstrated that the consideration of discontinuity sets in the orientation of excavation highly improves the mining conditions with or without support.
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