Modelamiento físico de flujo gravitacional en columnas de extracción altas.
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Date
2026
Authors
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Publisher
Universidad de Concepción
Abstract
La profundización de yacimientos en minería de caving ha introducido nuevas condiciones geomecánicas y de diseño, promoviendo el uso de columnas de extracción más altas para reducir costos. Esta profundización altera el flujo gravitacional, evidenciado por la aparición de material fino en los puntos de extracción, asociado a fragmentación secundaria o a material previamente quebrado en niveles superiores. En consecuencia, resulta necesario estudiar la propagación (vertical y lateral) y geometría de las zonas de flujo en este contexto, dado su impacto directo en el diseño y la operación minera.
Para abordar este estudio, se realizaron tres ensayos de modelamiento físico a escala 1:200, diseñados para cuantificar la geometría de las zonas de flujo en una columna de 200 cm (equivalente a 400 m en escala mina). El primer ensayo consideró una columna compuesta exclusivamente por material fino; el segundo incorporó material grueso en el primer tercio de la columna (67 cm), mientras que en el tercero dicha altura se redujo a la mitad (34 cm).
La metodología consistió en el llenado del modelo ubicando marcadores de extracción y líneas (marcadores) de flujo distribuidos a lo alto de la columna. Posteriormente, mediante tiraje aislado, se extrajo el material registrando los marcadores recuperados y capturando imágenes al final de cada periodo, con el fin de obtener las dimensiones de las zonas de flujo. Los diámetros máximos obtenidos para la zona de movimiento (IMZ) fueron 19, 42 y 20 cm, y para la zona de extracción (IEZ), 6, 15 y
12 cm, respectivamente. Los resultados se escalador y se utilizaron para evaluar la interacción del IMZ en una malla Teniente de 34 × 22 m. Se determinó que la interacción ocurre tras la extracción de 15, 6.7 y 7.25 kt en cada caso con una altura de interacción (HIZ) de 140, 5 y 27 m respectivamente. Posteriormente, se analizó la altura total del IMZ alcanzada en este punto, obteniendo valores de 300, 18 y 72 m.
Los ensayos permitieron identificar la influencia de la fragmentación en la geometría de las zonas de flujo. Donde una mayor proporción de material fino generó un menor diámetro, pero favorece un crecimiento vertical más rápido. En contraste, la presencia material grueso en la base aumenta los valores de diámetro, sin embargo, este deja de tener influencia en el diámetro máximo al reducir su proporción en la columna. Al llevar estos resultados a escala mina, se demuestra como un cambio en
la composición de una columna de extracción puede generar una gran diferencia en la propagación y geometría de las zonas de flujo, lo que influye en el diseño y operatividad de la mina.
The deepening of ore deposits in cave mining has introduced new geomechanics and design conditions, promoting the implementation of higher extraction columns to reduce capital costs. This deepening changes the gravity flow, demonstrated by the appearance of fine material in the extraction points, associated to secondary fragmentation mechanisms or due to broken material in superior levels. Consequently, it is necessary to study the propagation (vertical and lateral) and the flow zones geometry under this context, due to its direct effect in the operation and mine design. To approach this study, three physical model experiments were conducted at 1:200 scale, designed to quantify the flow zones geometry in a 200 cm column (400 m mine scale). The first experiment considered a column made of fine material; the second one included coarse material in the first third of the column (67 cm), whereas in the third experiment, this coarse material heigth was reduced to its half (34 cm). The methodology consisted on filling the model by placing extraction markers and flow lines located within the column. Later, by isolated draw, the material was extracted registering the markers obtained and taking pictures at the end of each period, in order to measure the flow zones dimensions. The maximum diameters observed for the movement zone (IMZ) were 19, 42 and 20 cm, whereas for the extraction zone (IEZ) were 6, 15 and 12 cm respectively. These results were scaled to evaluate the IMZ interaction in a 34 x 22 m Teniente layout. It was determined that the interaction occurs after 15, 6.7 and 7.25 kt extracted with a height (HIZ) of 140, 5 and 27 m. Finally, the IMZ total height measured at this point were 300, 18 and 72 m in each case. These experiments allowed to identify the fragmentation influence in the flow zones geometry, where a larger proportion of fine material resulted in a lower diameter, but promotes faster vertical growth. In contrast, the presence of coarse material in the base increase the diameter values, however, its influence is reduced as its proportion in the column decreases. When scaling these results, it is shown that how a change in the composition of the extraction column can cause big differences in the propagation and geometry of the flow zones, which directly influences the operation and mine design.
The deepening of ore deposits in cave mining has introduced new geomechanics and design conditions, promoting the implementation of higher extraction columns to reduce capital costs. This deepening changes the gravity flow, demonstrated by the appearance of fine material in the extraction points, associated to secondary fragmentation mechanisms or due to broken material in superior levels. Consequently, it is necessary to study the propagation (vertical and lateral) and the flow zones geometry under this context, due to its direct effect in the operation and mine design. To approach this study, three physical model experiments were conducted at 1:200 scale, designed to quantify the flow zones geometry in a 200 cm column (400 m mine scale). The first experiment considered a column made of fine material; the second one included coarse material in the first third of the column (67 cm), whereas in the third experiment, this coarse material heigth was reduced to its half (34 cm). The methodology consisted on filling the model by placing extraction markers and flow lines located within the column. Later, by isolated draw, the material was extracted registering the markers obtained and taking pictures at the end of each period, in order to measure the flow zones dimensions. The maximum diameters observed for the movement zone (IMZ) were 19, 42 and 20 cm, whereas for the extraction zone (IEZ) were 6, 15 and 12 cm respectively. These results were scaled to evaluate the IMZ interaction in a 34 x 22 m Teniente layout. It was determined that the interaction occurs after 15, 6.7 and 7.25 kt extracted with a height (HIZ) of 140, 5 and 27 m. Finally, the IMZ total height measured at this point were 300, 18 and 72 m in each case. These experiments allowed to identify the fragmentation influence in the flow zones geometry, where a larger proportion of fine material resulted in a lower diameter, but promotes faster vertical growth. In contrast, the presence of coarse material in the base increase the diameter values, however, its influence is reduced as its proportion in the column decreases. When scaling these results, it is shown that how a change in the composition of the extraction column can cause big differences in the propagation and geometry of the flow zones, which directly influences the operation and mine design.
Description
Tesis presentada para optar al título de Ingeniero/a Civil de Minas.
Keywords
Yacimientos minerales, Gravitación, Explotación minera