Estimación del desplazamiento esperado entre componentes críticos de un molino semiautógeno SAG.
Date
2025
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
Chile es uno de los principales países mineros del mundo, produciendo aproximadamente un 25% del suministro mundial de cobre (SERNAGEOMIN, 2023). Dentro de este contexto, los molinos semiautógenos (SAG) cumplen una función fundamental en la conminución de minerales, destacándose por su capacidad para procesar grandes volúmenes de material de manera eficiente. Estos equipos están compuestos principalmente por un estator, un molino y su fundación.
El principal objetivo de este trabajo es estimar los desplazamientos en el air-gap entre el estator y el rotor de un molino SAG utilizando el espectro de referencia establecido en la norma NCh2369:2023 (INN, 2023), dado que actualmente se discute si este espectro es adecuado para calcular dichas deformaciones. Para ello, se desarrolló un modelo tridimensional del molino en SAP2000, incluyendo sus principales componentes: el molino, la fundación y el estator. Posteriormente, se evaluaron los desplazamientos en el air-gap mediante análisis modal espectral y análisis tiempo-historia lineal. En estos últimos, utilizaron registros sísmicos consistentes con dicho espectro de referencia.
Los resultados indican que, en la mayoría de los casos, los desplazamientos obtenidos son inferiores a los 20 mm del air-gap diseñado en el molino SAG real. Sin embargo, se determinó que hay una probabilidad de que este límite se supere, por lo que fue necesario elaborar una curva de fragilidad para evaluar el riesgo de falla en este espacio. Esta curva demostró que el riesgo asociado al diseño del air-gap utilizando el espectro de la norma NCh2369:2023 (INN, 2023) es aproximadamente del 10%.
Además, se propuso una metodología para evaluar la fluencia de los pernos de anclaje en los apoyos del molino durante los análisis de tiempo-historia lineales. Los resultados mostraron que estos pernos podrían experimentar fluencia bajo los sismos de diseño, lo que podría afectar los desplazamientos del air-gap. Esto sugiere la necesidad de incluir explícitamente estos elementos en el modelo para analizar este comportamiento en futuros estudios.
Chile is one of the main mining countries in the world, producing approximately 25% of the world's copper supply (SERNAGEOMIN, 2023). Within this context, semi-autogenous mills (SAG) play a fundamental role in the comminution of minerals, standing out for their capacity to process large volumes of material efficiently. These equipments are mainly composed of a stator, a mill and its foundation. The main objective of this work is to estimate the displacements in the air-gap between the stator and the rotor of a SAG mill using the reference spectrum established in the standard NCh2369:2023 (INN, 2023), since it is currently being discussed whether this spectrum is adequate to calculate such deformations. For this purpose, a three-dimensional model of the mill was developed in SAP2000, including its main components: the mill, the foundation and the stator. Subsequently, the displacements in the air-gap were evaluated by means of spectral modal analysis and linear time-history analysis. In the latter, they used seismic records consistent with the reference spectrum. The results indicate that, in most cases, the displacements obtained are less than the 20 mm of the air gap designed in the real SAG mill. However, it was determined that there is a probability that this limit will be exceeded, so it was necessary to develop a fragility curve to assess the risk of failure in this space. This curve showed that the risk associated with the air-gap design using the spectrum of NCh2369:2023 (INN, 2023) is approximately 10%. In addition, a methodology was proposed to evaluate the creep of anchor bolts in the mill supports during linear time-history analyses. The results showed that these bolts could experience creep under design earthquakes, which could affect the air-gap displacements. This suggests the need to explicitly include these elements in the model to analyze this behavior in future studies.
Chile is one of the main mining countries in the world, producing approximately 25% of the world's copper supply (SERNAGEOMIN, 2023). Within this context, semi-autogenous mills (SAG) play a fundamental role in the comminution of minerals, standing out for their capacity to process large volumes of material efficiently. These equipments are mainly composed of a stator, a mill and its foundation. The main objective of this work is to estimate the displacements in the air-gap between the stator and the rotor of a SAG mill using the reference spectrum established in the standard NCh2369:2023 (INN, 2023), since it is currently being discussed whether this spectrum is adequate to calculate such deformations. For this purpose, a three-dimensional model of the mill was developed in SAP2000, including its main components: the mill, the foundation and the stator. Subsequently, the displacements in the air-gap were evaluated by means of spectral modal analysis and linear time-history analysis. In the latter, they used seismic records consistent with the reference spectrum. The results indicate that, in most cases, the displacements obtained are less than the 20 mm of the air gap designed in the real SAG mill. However, it was determined that there is a probability that this limit will be exceeded, so it was necessary to develop a fragility curve to assess the risk of failure in this space. This curve showed that the risk associated with the air-gap design using the spectrum of NCh2369:2023 (INN, 2023) is approximately 10%. In addition, a methodology was proposed to evaluate the creep of anchor bolts in the mill supports during linear time-history analyses. The results showed that these bolts could experience creep under design earthquakes, which could affect the air-gap displacements. This suggests the need to explicitly include these elements in the model to analyze this behavior in future studies.
Description
Tesis presentada para optar al título de Ingeniero/a Civil.
Keywords
Molinos Diseño, Industria minera, Minerales de cobre