Thesis ESTUDIO GEOMECÁNICO DEL EFECTO DE RELLENAR EL CRÁTER DE UNA EXPLOTACIÓN BLOCK CAVING CON RELAVE
Date
2020-05
Authors
RAMÍREZ BÓRQUEZ, JAVIER IVÁN NICOLÁS
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Abstract
En la actualidad, los tranques de relaves producen un problema social, espacial y medioambiental en todos los países mineros. Por este motivo, es necesario desarrollar nuevas tecnologías que permitan la depositación masiva de relaves de manera sustentable. En este contexto, la empresa JRI Ingeniería S.A. propone el método denominado Wasteless Mining (WLM®), el que consiste en depositar los relaves producto de la recuperación de Cobre en una planta de procesamiento de sulfuros, dentro de la oquedad que se genera al explotar la mina subterránea. Este sistema tiene como objetivo principal eliminar la construcción de depósitos de relaves, y así lograr mayor sustentabilidad en los proyectos mineros. En esta memoria de título se realiza un análisis geomecánico, mediante modelamiento numérico, del efecto que tiene rellenar el cráter provocado por una mina subterránea explotada por el método de hundimiento (block caving), en la superficie del terreno natural. Este análisis se desarrolla para un proyecto minero Demo WLM® que se llevará a cabo en un yacimiento cuprífero ubicado en la región de Atacama, Chile. Para realizar el análisis geomecánico se utilizan modelos numéricos bidimensionales y tridimensionales, usando FLAC (Itasca CG Inc., 2016) y FLAC3D (Itasca CG Inc., 2017), programas formulados con la teoría de diferencias finitas. Además, se realizaron modelos más simples aplicando el programa Phase2 (Rocscience, 2009), basado en análisis bidimensional de elementos finitos. Adicionalmente, se realiza el diseño de la instrumentación geomecánica del proyecto considerando los resultados de la simulación numérica, cuya finalidad es comprobar los resultados obtenidos en el modelo. La instrumentación consiste en un sistema de monitoreo conformado por sensores que permitan medir desplazamientos superficiales del cráter, estado tensional in situ y su evolución con el tiempo, sismicidad durante el hundimiento, y formación de grietas en la superficie del terreno natural influenciada por el hundimiento. Además, se analiza el uso de trazadores radioactivos para monitorear el descenso de los relaves en el interior del cráter del hundimiento. Luego de analizar los resultados de los modelos, se verifica el efecto positivo que genera aplicar el método WLM en el Proyecto Demo, al disminuir la zona de influencia producto de la subsidencia. Este método permitiría acercar la zona de explotación minera a cualquier tipo de infraestructura, permitiendo disminuir el espacio que ocupa la faena minera. Lo anterior cobra vital importancia cuando el yacimiento se encuentra cercano a un pueblo, glaciar, monumentos históricos y patrimonios culturales, minimizando el impacto en las personas. Sin embargo, cada modelo entrega distintos grados de disminución en la zona afectada por la subsidencia. Esto se debe a las características geométricas de la mina subterránea, de la calidad del macizo rocoso y del estado tensional consideradas en cada modelo.
Actually, tailing dams cause a social, spatial and environmental issue in all mining countries. Therefore, it’s necessary to develop new technologies that allow the massive deposition in a sustainable way. Thus, the company JRI Ingenieria S.A. proposes Waste Less Mining (WLM®) method, which is depositing the tailings resultant of copper recuperation in a sulfide plant, inside of the cavity generated by the underground mining. The principal objectives of this system are eradicating the construction of tailing dams and achieve greater sustainability in mining projects. In this title report, a geomechanical analysis of the effect of filling the crater induced by an underground mine operated by block caving method, in the surface of natural ground, is done. This analysis is developed for a Demo WLM® mining project that will take place in the copper deposit Inca de Oro, located in Atacama region, Chile. To develop the geomechanical analysis, bidimensional and tridimensional numeric models are used, in FLAC (Itasca CG Inc., 2016) and FLAC3D (Itasca CG Inc., 2017) software, both based on an explicit finite difference formulation. Besides, this is supported by models prepared in Phase2 (Rocscience, 2009), based on bidimensional analysis of finite elements. Furthermore, geomechanical instrumentation design of the project based on the results of numeric simulation is done, whose objective is to confirm the results of the model. The instrumentation is a monitoring system formed by sensors that allow measuring superficial displacement of the crater, in situ tensional state and his evolution, seismicity during caving, and crack formation in the natural ground surface affected by the caving. Thereby, the use of radioactive tracers to monitor the descent of the tailings inside the crater is analyzed. After analyzing the model’s results, it is verified the positive effect of the WLM method in the Demo Proyect, minimizing the superficial zone influenced by the subsidence. This makes possible to bring any infrastructure closer to the mine, allowing to reduce the occupied space of the mine site. This is significant when the deposit is near to a town, glacier, historical monuments and cultural heritage, decreasing the negative impact on people. However, every model gives different magnitude of decrease of the zone influenced by the subsidence. This is explained by the geometrical features of the underground mining, the quality of the rock mass and the tensional state considered in each model.
Actually, tailing dams cause a social, spatial and environmental issue in all mining countries. Therefore, it’s necessary to develop new technologies that allow the massive deposition in a sustainable way. Thus, the company JRI Ingenieria S.A. proposes Waste Less Mining (WLM®) method, which is depositing the tailings resultant of copper recuperation in a sulfide plant, inside of the cavity generated by the underground mining. The principal objectives of this system are eradicating the construction of tailing dams and achieve greater sustainability in mining projects. In this title report, a geomechanical analysis of the effect of filling the crater induced by an underground mine operated by block caving method, in the surface of natural ground, is done. This analysis is developed for a Demo WLM® mining project that will take place in the copper deposit Inca de Oro, located in Atacama region, Chile. To develop the geomechanical analysis, bidimensional and tridimensional numeric models are used, in FLAC (Itasca CG Inc., 2016) and FLAC3D (Itasca CG Inc., 2017) software, both based on an explicit finite difference formulation. Besides, this is supported by models prepared in Phase2 (Rocscience, 2009), based on bidimensional analysis of finite elements. Furthermore, geomechanical instrumentation design of the project based on the results of numeric simulation is done, whose objective is to confirm the results of the model. The instrumentation is a monitoring system formed by sensors that allow measuring superficial displacement of the crater, in situ tensional state and his evolution, seismicity during caving, and crack formation in the natural ground surface affected by the caving. Thereby, the use of radioactive tracers to monitor the descent of the tailings inside the crater is analyzed. After analyzing the model’s results, it is verified the positive effect of the WLM method in the Demo Proyect, minimizing the superficial zone influenced by the subsidence. This makes possible to bring any infrastructure closer to the mine, allowing to reduce the occupied space of the mine site. This is significant when the deposit is near to a town, glacier, historical monuments and cultural heritage, decreasing the negative impact on people. However, every model gives different magnitude of decrease of the zone influenced by the subsidence. This is explained by the geometrical features of the underground mining, the quality of the rock mass and the tensional state considered in each model.
Description
Keywords
TRANQUES DE RELAVE , DEPOSITOS DE RELAVES , GEOLOGIA DE MINAS