Thesis ENSAYOS DE CONMINUCIÓN PARA EVALUAR EL EFECTO DE LA APLICACIÓN DE MICROONDAS A MUESTRAS MINERALES
Date
2018
Authors
OLMOS GONZÁLEZ, BÁRBARA BELÉN
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Abstract
El presente trabajo analiza el desempeño de dos técnicas propuestas para evaluar el efecto de tratamientos con microondas sobre minerales de cobre, con el propósito de reducir el consumo de energía en molienda. Los métodos comúnmente aceptados en la industria no son apropiados ya sea por la cantidad de muestra que demandan, o el tamaño de mineral que requieren. El trabajo de laboratorio que da origen al tema requiere de técnicas para medir y evaluar el resultado de experimentos donde se ensaya muestras de 6 [gr] (masa máxima por prueba), compuestas de partículas cuyos tamaños se encuentran entre 4 y 12 [mm]. Se trata de lograr un ciclo de aprendizaje corto entre formulación de hipótesis, experimentación y análisis, para avanzar a un ritmo adecuado en la investigación y con bajos costos.La primera técnica ensayada es la compresión monopartícula, donde se colecta información sobre fuerza y desplazamiento para colapsar partículas individuales de tamaños similares. La repetición de este ensayo n veces permite obtener una probabilidad de fractura en función de la carga aplicada, la que es usada como caracterización de la conducta del material, y donde sus parámetros característicos (media, mediana, resistencia del 80%, etc.) son usados para evaluar el efecto de los tratamientos.La segunda técnica es una versión en pequeña escala del ensayo Drop Weight Test, propuesto por Schoenert y desarrollado industrialmente en Australia por el centro JK de la Univ. de Queensland. Las partículas de diversos tamaños son trituradas dejando caer bolas de masa conocida desde una altura controlada (es decir, con una energía conocida), y se evalúan los parámetros tn de la distribución de tamaño de los fragmentos.Los resultados experimentales muestran que cada una es capaz de producir resultados consistentes, pero a su vez, que los efectos de las microondas son dispares. Las nuevas hipótesis que se derivan del trabajo realizado son que el proceso con microondas no está aún claramente perfilado en sus condiciones, y que su efecto principal y más relevante podría no estar en la energía ahorrada, sino en la liberación de la mena por el tipo de fractura inducida.
This thesis studies the performance of two methods about evaluating the effect of microwaves on copper ores, in order to reduce energy consumption on grinding. Widely-accepted methods in the mining industry are not accepted either the amount of sample or size fraction required for the test.Laboratory work requires of methods for measuring and evaluating experimental results where samples of 6 g (maximum mass per test) are used, composed by particles with size fraction between 4 and 12 mm. the aim is to achieve a short learning cycle between hypothesis, experimental work and analysis, in order to move along a proper work-rhythm for the research and with low costs.The first tested method is monoparticle compression, where information on force and displacement is collected to collapse single particles of similar sizes. The development of this test n-times can get a probability of fracture as a function of applied load, which is used as a characterization of ore behavior and key-parameters (mean, median, 80%-resistance) are used to evaluate the effect of the treatment.The second method is a low-scale version of Drop Weight Test, proposed by Schoenert and industrially developed in Australia by JK center of the University of Queensland. Particles of several sizes are crushed by dropping balls of known mass form a controlled height (i.e., with known energy) and the parameters “tn” of size distribution of the fragments are evaluated.The experimental results show each method is able to produce consistent results, but the effect of microwaves is disparate. New hypothesis from this work state the process with microwaves is not clearly outlined in its conditions, and the main and relevant effect might not be in the saved energy but in ore liberation by the kind of induced fracture.
This thesis studies the performance of two methods about evaluating the effect of microwaves on copper ores, in order to reduce energy consumption on grinding. Widely-accepted methods in the mining industry are not accepted either the amount of sample or size fraction required for the test.Laboratory work requires of methods for measuring and evaluating experimental results where samples of 6 g (maximum mass per test) are used, composed by particles with size fraction between 4 and 12 mm. the aim is to achieve a short learning cycle between hypothesis, experimental work and analysis, in order to move along a proper work-rhythm for the research and with low costs.The first tested method is monoparticle compression, where information on force and displacement is collected to collapse single particles of similar sizes. The development of this test n-times can get a probability of fracture as a function of applied load, which is used as a characterization of ore behavior and key-parameters (mean, median, 80%-resistance) are used to evaluate the effect of the treatment.The second method is a low-scale version of Drop Weight Test, proposed by Schoenert and industrially developed in Australia by JK center of the University of Queensland. Particles of several sizes are crushed by dropping balls of known mass form a controlled height (i.e., with known energy) and the parameters “tn” of size distribution of the fragments are evaluated.The experimental results show each method is able to produce consistent results, but the effect of microwaves is disparate. New hypothesis from this work state the process with microwaves is not clearly outlined in its conditions, and the main and relevant effect might not be in the saved energy but in ore liberation by the kind of induced fracture.
Description
Catalogado desde la version PDF de la tesis.
Keywords
DROP WEIGHT TESTER , FRACTURA EN CONMINUCIÓN , MICROONDAS