Publication: ANALISIS DE ESTABILIDAD DE UN DEPOSITO DE RELAVES ESPESADOS EMPLAZADO SOBRE UN TRANQUE DE RELAVES CONVENCIONAL
Date
2017
Authors
BARRIOS GARCÍA, JUAN JOSÉ
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Abstract
Chile produce actualmente 1.5 millones de toneladas de relaves por día como resultado de los procesos de concentración de minerales de cobre. Debido a las bajas leyes de mineral (bajo el 1%), así como la adopción de economías de escala, esta producción se podría duplicar en las próximas décadas. La forma convencional de almacenar estos relaves es en tranques o embalses los que pueden alcanzar alturas por sobre los 250 m. Las fallas estructurales de estos depósitos, así como la necesidad de aumentar la reutilización de agua en los procesos de extracción, ha llevado a la industria a utilizar la técnica de disposición de relaves espesados cuya mayor virtud es la disminución del contenido de agua en la pulpa de relaves. Sin embargo, el aumento en la producción de relaves sumado a la falta de espacio para construir nuevos depósitos (especialmente en Chile central) han llevado a ingenieros geotécnicos a pensar en disponer relaves espesados por sobre estructuras de almacenamiento convencionales. Sin embargo, esto presenta incertidumbres respecto a la estabilidad geomecánica global de la estructura resultante.En este contexto, el presente trabajo de título corresponde a un análisis de estabilidad estática, sísmica y post-sísmica de un depósito de relaves combinado, además del depósito convencional para así comparar ambos desempeños. El estudio se enmarca en el programa de memorias de la División Andina de Codelco en la ciudad de Los Andes. Para la realización del trabajo, la empresa proporcionó información existente referida al tranque Ovejería, el que utiliza actualmente la división para almacenar los desechos o relaves de su proceso productivo.Para llevar a cabo el análisis de estabilidad, se elaboró un modelo del tranque Ovejería utilizando el software de elementos finitos (FEM), un escenario en condiciones actuales, otro escenario de largo plazo funcionando de manera convencional, y el último funcionando como depósito combinado.
Chile generates actually 1.5 million tons of tailings per day as a result of the copper ore concentration processes. Due to the low copper grades (under 1%) as well as the adoption of economies of scale, this production may double over the following decades. These tailings are disposed conventionally in tailings dams which can reach heights of above 250 meters. The structural tailings dam failures as well as the need to increase the recovery of water from their concentration processes, have led the industry to adopt a new disposal method called “thickened tailings disposal”. This main advantage of the method is that increases the solid content (above 55%, approximately) of the tailings, improving the use of water and increasing physical stability of the resultant material. Nevertheless, the lack of space in central Chile, where most of new mining concession concentrate, have led geotechnical engineers to evaluate the disposal of thickened tailings over conventional existent dams. The use of this strategy also possesses a series of uncertainties about the geomechanical stability of the resultant structure (the combined structure).In this context, the present study analyses the static, seismic and post-seismic response of the combined tailings storage facility, i.e. thickened tailings deposit underlined by a tailings dam. This research is part of the program “Programa de Memorias” of Codelco in the Division Andina, Los Andes, Chile. In order to carry out the work, the company provided existing information regarding the Ovejería dam, which currently uses the division to dispose the tailings from the underground mine Río Blanco and the open pit mine Sur Sur. In addition, experimental results from tests conducted on thickened tailings and rate of rise plans are considered in the analysis.In order to carry out the structural response analysis, a model of the Ovejería dam was developed using finite element (FEM) software in order to explore the stability of the conventional and the combined facility. As a result of the analysis, stresses, deformation and displacement fields were obtained, as well as static and post-seismic (assuming total liquefaction) safety factors.
Chile generates actually 1.5 million tons of tailings per day as a result of the copper ore concentration processes. Due to the low copper grades (under 1%) as well as the adoption of economies of scale, this production may double over the following decades. These tailings are disposed conventionally in tailings dams which can reach heights of above 250 meters. The structural tailings dam failures as well as the need to increase the recovery of water from their concentration processes, have led the industry to adopt a new disposal method called “thickened tailings disposal”. This main advantage of the method is that increases the solid content (above 55%, approximately) of the tailings, improving the use of water and increasing physical stability of the resultant material. Nevertheless, the lack of space in central Chile, where most of new mining concession concentrate, have led geotechnical engineers to evaluate the disposal of thickened tailings over conventional existent dams. The use of this strategy also possesses a series of uncertainties about the geomechanical stability of the resultant structure (the combined structure).In this context, the present study analyses the static, seismic and post-seismic response of the combined tailings storage facility, i.e. thickened tailings deposit underlined by a tailings dam. This research is part of the program “Programa de Memorias” of Codelco in the Division Andina, Los Andes, Chile. In order to carry out the work, the company provided existing information regarding the Ovejería dam, which currently uses the division to dispose the tailings from the underground mine Río Blanco and the open pit mine Sur Sur. In addition, experimental results from tests conducted on thickened tailings and rate of rise plans are considered in the analysis.In order to carry out the structural response analysis, a model of the Ovejería dam was developed using finite element (FEM) software in order to explore the stability of the conventional and the combined facility. As a result of the analysis, stresses, deformation and displacement fields were obtained, as well as static and post-seismic (assuming total liquefaction) safety factors.
Description
Catalogado desde la version PDF de la tesis.
Keywords
DINAMICA Y POST-SISMICA , ESTABILIDAD ESTATICA , LICUEFACCION , RELAVES CONVENCIONALES , RELAVES ESPESADOS , TRANQUE COMBINADO