Determinación experimental del comportamiento hidráulico de medios con saturación variable.
Loading...
Date
2026
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
La lixiviación en pilas exige conocer con precisión el comportamiento hidráulico del material para definir tasas de riego que maximicen la recuperación sin comprometer la estabilidad de la pila. En esta memoria se determinó experimentalmente la relación entre presión y contenido de humedad volumétrico (volumetric water content, VWC) de un suelo granular de textura arenosa (regolito o “maicillo”), con el fin de obtener su curva de retención de humedad (SWRC) y la función de conductividad hidráulica no saturada K(h) bajo condiciones de saturación variable.
En primer lugar, se caracterizó el material mediante granulometría y clasificación textural USDA, confirmando su carácter predominantemente arenoso. Posteriormente se realizaron cuatro ensayos de drenaje en un equipo de presión (filtra test), aplicando presiones entre 1 y 500 kPa sobre muestras saturadas, mientras se registraba el contenido de humedad con el sensor MAS-1 conectado a un data logger LogBox BLE. A partir de los datos contenido de humedad y presión se construyó la
SWRC y se ajustó mediante el modelo de van Genuchten utilizando RETC; la conductividad hidráulica saturada se obtuvo con un permeámetro de carga constante diseñado según normativa ASTM. Con los parámetros ajustados (θr, θs, α, n, Ks) se estimó la función conductividad en HYDRUS-1D y se transformó en tasas de riego equivalentes, identificando ventanas operativas para condiciones de lixiviación.
Las curvas de retención de humedad muestran el comportamiento típico de suelos arenosos: una zona de saturación efectiva a bajas presiones, una transición pronunciada donde pequeñas variaciones en la presión producen cambios significativos en el contenido de humedad y una zona residual con drenaje lento. La función conductividad permanece prácticamente constante a presiones bajas y luego decrece bruscamente, evidenciando alta porosidad y rápida pérdida de conectividad de poros. Se identificó un tramo sensible (log(h) ≈ 1 – 2), en el cual variaciones moderadas de presión sufre cambios importantes en la conductividad, definiendo un límite operativo para evitar encharcamientos, flujos preferenciales y una disminución de la eficiencia de lixiviación. El procedimiento desarrollado demuestra que es posible obtener de forma reproducible la SWRC y K(h) de materiales granulares y proporciona una base cuantitativa para el diseño hidráulico de pilas de lixiviación.
Heap leaching operations require an accurate hydraulic characterization of the ore bed to define irrigation rates that maximize metal recovery while preserving heap stability. This thesis experimentally determined the relationship between pression and water content for a granular, sandy saprolite to derive its soil water retention curve (SWRC) and the unsaturated hydraulic conductivity function K(h) under variable saturation. The material was first characterized by grain-size distribution and USDA textural classification, confirming a predominantly sandy texture. Four controlled-suction drainage tests were then performed in a pressure apparatus (filtra test), applying air pressures between 1 and 500 kPa to saturated samples while recording volumetric water content with a MAS-1 sensor connected to a LogBox BLE datalogger. From the volumetric water content and pressure data, the SWRC was constructed and fitted with the van Genuchten model in RETC, whereas the saturated hydraulic conductivity was obtained using a constant-head permeameter designed according to ASTM guidelines. The fitted parameters (θr, θs, α, n, Ks) were subsequently used in HYDRUS-1D to estimate K(h), which was converted into equivalent irrigation rates to delineate operational windows for heap leach conditions. The resulting SWRCs exhibit the characteristic behavior of sandy materials, with an effective saturation zone at low suctions, a sharp transition where small changes in pression induce large variations in water content, and a residual zone with slow drainage. The K(h) function remains nearly constant at low pressures and then drops rapidly, indicating high porosity and a fast loss of pore connectivity. A particularly sensitive interval (log(h) ≈ 1–2) was identified, in which moderate changes in pression lead to pronounced variations in hydraulic conductivity, thus defining an operational limit beyond which ponding, preferential flow and reduced leaching efficiency are more likely. The developed procedure proves that it is feasible to reproducibly obtain SWRC and K(h) for granular materials and provides a quantitative basis for hydraulic design and optimization of industrial heap leach systems.
Heap leaching operations require an accurate hydraulic characterization of the ore bed to define irrigation rates that maximize metal recovery while preserving heap stability. This thesis experimentally determined the relationship between pression and water content for a granular, sandy saprolite to derive its soil water retention curve (SWRC) and the unsaturated hydraulic conductivity function K(h) under variable saturation. The material was first characterized by grain-size distribution and USDA textural classification, confirming a predominantly sandy texture. Four controlled-suction drainage tests were then performed in a pressure apparatus (filtra test), applying air pressures between 1 and 500 kPa to saturated samples while recording volumetric water content with a MAS-1 sensor connected to a LogBox BLE datalogger. From the volumetric water content and pressure data, the SWRC was constructed and fitted with the van Genuchten model in RETC, whereas the saturated hydraulic conductivity was obtained using a constant-head permeameter designed according to ASTM guidelines. The fitted parameters (θr, θs, α, n, Ks) were subsequently used in HYDRUS-1D to estimate K(h), which was converted into equivalent irrigation rates to delineate operational windows for heap leach conditions. The resulting SWRCs exhibit the characteristic behavior of sandy materials, with an effective saturation zone at low suctions, a sharp transition where small changes in pression induce large variations in water content, and a residual zone with slow drainage. The K(h) function remains nearly constant at low pressures and then drops rapidly, indicating high porosity and a fast loss of pore connectivity. A particularly sensitive interval (log(h) ≈ 1–2) was identified, in which moderate changes in pression lead to pronounced variations in hydraulic conductivity, thus defining an operational limit beyond which ponding, preferential flow and reduced leaching efficiency are more likely. The developed procedure proves that it is feasible to reproducibly obtain SWRC and K(h) for granular materials and provides a quantitative basis for hydraulic design and optimization of industrial heap leach systems.
Description
Tesis presentada para optar al título de Ingeniero/a Civil de Minas.
Keywords
Lixiviación, Minerales de cobre, Hidrometalurgia