Impacto de una poliacrilamida aniónica residual y su nivel de degradación mecánica en la flotación de calcopirita en presencia de caolinita.
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Date
2025
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Universidad de Concepción
Abstract
La industria del procesamiento de minerales enfrenta actualmente dos desafíos críticos: la disminución progresiva de las leyes de mineral y la creciente escasez de agua fresca. Este último ha sido abordado mediante un aumento en la recirculación de agua de proceso, lo que conlleva una disminución en su calidad debido a la acumulación de especies indeseadas, como floculantes residuales de tipo poliacrilamida (PAM). La presencia de estos reactivos puede afectar negativamente la flotabilidad de minerales valiosos como los sulfuros de cobre y alterar sus interacciones con minerales de ganga como la caolinita.
El objetivo de esta tesis de Doctorado fue investigar el impacto de las moléculas de PAM, sometidas a distintos niveles de degradación mecánica, sobre las propiedades superficiales y la flotación de calcopirita en presencia y ausencia de caolinita, bajo diferentes condiciones fisicoquímicas. La metodología experimental incluyó ensayos de microflotación, mediciones de tiempo de inducción, isotermas de adsorción de reactivos, voltamperometrías cíclicas y ensayos de movilidad electroforética. Los resultados obtenidos demostraron que la presencia de PAM afecta negativamente la flotación de calcopirita y que su magnitud depende del pH y de la conformación molecular del polímero. A valores de pH entre 7 y 9, las moléculas no degradadas de PAM exhibieron mayor adsorción y un efecto depresor más pronunciado, mientras que a pH 11 las moléculas fuertemente degradadas mostraron mayor adsorción, favorecida por la presencia de sitios hidroxilados y la fragmentación del polímero. Este comportamiento se atribuye principalmente al recubrimiento superficial hidrofílico generado por la adsorción de PAM, que incrementa el tiempo de inducción y actúa como una barrera estérica, inhibiendo la interacción entre los colectores y la calcopirita. En los sistemas mixtos, la combinación de PAM y caolinita provocó una depresión más severa que la observada para cada componente por separado, lo que sugiere que la presencia de floculantes residuales en el agua de proceso podría intensificar el impacto negativo de las arcillas sobre la eficiencia del proceso de flotación. Además, la presencia de PAM en estas mezclas redujo aún más la adsorción de PAX, acentuando la pérdida de flotabilidad de la calcopirita.
Estos antecedentes permiten concluir que una gestión adecuada del agua de proceso resulta fundamental para optimizar las operaciones de flotación y así mejorar la eficiencia de la producción de cobre. Asimismo, los resultados destacan la influencia combinada de los floculantes residuales y minerales de ganga como la caolinita sobre la química superficial de los sistemas de flotación, lo cual plantea la necesidad de controlar no solo la disponibilidad hídrica y la presencia de arcillas, sino también la calidad del agua recirculada en los circuitos de las plantas concentradoras.
The mineral processing industry is currently facing two critical challenges: the progressive decline in ore grades and the growing scarcity of fresh water. The latter has been addressed by increasing the recirculation of process water, which leads to a decrease in its quality due to the accumulation of undesirable species, such as residual polyacrylamide (PAM) flocculants. The presence of these reagents can negatively affect the floatability of valuable minerals such as copper sulfides and alter their interactions with gangue minerals such as kaolinite. The objective of this work was to investigate the impact of PAM molecules, subjected to different levels of mechanical degradation, on the surface properties and flotation of chalcopyrite in the presence and absence of kaolinite, under different physicochemical conditions. The experimental methodology included microflotation tests, induction time measurements, reagent adsorption isotherms, cyclic voltammetry, and electrophoretic mobility tests. The results obtained showed that the presence of PAM negatively affects chalcopyrite flotation and that its magnitude depends on the pH and the polymer structure. At pH between 7 and 9, the non-degraded molecules exhibited greater adsorption and a more pronounced depressing effect, while at pH 11 the strongly degraded molecules showed greater adsorption, favored by the presence of hydroxylated sites and polymer fragmentation. This behavior is mainly attributed to the hydrophilic surface coating generated by the adsorption of PAM, which increases the induction time and acts as a steric barrier, inhibiting the interaction between the collectors and chalcopyrite. In mixed systems, the combination of PAM and kaolinite caused a more severe depression than that observed for each component separately, suggesting that the presence of residual flocculants in the recirculated process water could intensify the negative impact of clays on flotation efficiency. In addition, the presence of PAM in these mixtures further reduced the adsorption of PAX, accentuating the loss of chalcopyrite floatability. This background supports the conclusion that proper management of process water is essential to optimize flotation operations and improve copper production efficiency. The results also highlight the combined influence of residual flocculants and gangue minerals such as kaolinite on the surface chemistry of flotation systems, emphasizing the need to control not only water availability and clay content, but also the quality of recirculated water in concentrator circuits.
The mineral processing industry is currently facing two critical challenges: the progressive decline in ore grades and the growing scarcity of fresh water. The latter has been addressed by increasing the recirculation of process water, which leads to a decrease in its quality due to the accumulation of undesirable species, such as residual polyacrylamide (PAM) flocculants. The presence of these reagents can negatively affect the floatability of valuable minerals such as copper sulfides and alter their interactions with gangue minerals such as kaolinite. The objective of this work was to investigate the impact of PAM molecules, subjected to different levels of mechanical degradation, on the surface properties and flotation of chalcopyrite in the presence and absence of kaolinite, under different physicochemical conditions. The experimental methodology included microflotation tests, induction time measurements, reagent adsorption isotherms, cyclic voltammetry, and electrophoretic mobility tests. The results obtained showed that the presence of PAM negatively affects chalcopyrite flotation and that its magnitude depends on the pH and the polymer structure. At pH between 7 and 9, the non-degraded molecules exhibited greater adsorption and a more pronounced depressing effect, while at pH 11 the strongly degraded molecules showed greater adsorption, favored by the presence of hydroxylated sites and polymer fragmentation. This behavior is mainly attributed to the hydrophilic surface coating generated by the adsorption of PAM, which increases the induction time and acts as a steric barrier, inhibiting the interaction between the collectors and chalcopyrite. In mixed systems, the combination of PAM and kaolinite caused a more severe depression than that observed for each component separately, suggesting that the presence of residual flocculants in the recirculated process water could intensify the negative impact of clays on flotation efficiency. In addition, the presence of PAM in these mixtures further reduced the adsorption of PAX, accentuating the loss of chalcopyrite floatability. This background supports the conclusion that proper management of process water is essential to optimize flotation operations and improve copper production efficiency. The results also highlight the combined influence of residual flocculants and gangue minerals such as kaolinite on the surface chemistry of flotation systems, emphasizing the need to control not only water availability and clay content, but also the quality of recirculated water in concentrator circuits.
Description
Tesis presentada para optar al grado de Doctor/a en Ingeniería Metalúrgica.
Keywords
Poliacrilamida, Calcopirita, Flotación (Minerales)