Abstract

The mineral processing industry currently faces two critical challenges: (1) the progressive decline in ore grades, which leads to an increased presence of complex gangue minerals, and (2) the growing scarcity of fresh water. The second challenge has been addressed by increasing the recirculation of process water, which alters water quality due to the accumulation of impurities such as residual flocculants like polyacrylamides (PAMs). These reagents may play an important role in the interactions between valuable copper sulfides and clay minerals such as kaolinite. The objective of this work was to evaluate the influence of an anionic PAM with a degree of anionicity (DA) of 8.15% under various levels of mechanical degradation on chalcopyrite flotation in the presence of kaolinite. Microflotation, induction time, PAM adsorption, electrophoretic mobility, and potassium amyl xanthate (PAX) adsorption experiments were carried out in this study. The results of this work showed that the presence of PAM and kaolinite in the chalcopyrite flotation systems negatively affects mineral recovery due to complex adsorption interactions influenced by pH and polymer degradation. The obtained results demonstrated that the combined depressing effect of PAM and kaolinite on chalcopyrite is stronger than their individual effects, highlighting important industrial implications by suggesting that the presence of residual flocculants in process water may enhance the negative impact of clay minerals on flotation performance. PAM molecules also inhibit PAX adsorption in slurries composed by a mixture of chalcopyrite and kaolinite, further reducing chalcopyrite flotation efficiency. These findings highlight the combined influence of residual flocculants and gangue minerals such as kaolinite on the surface chemistry of flotation systems. This emphasizes the need to manage not only the presence of clay minerals, but also the quality of recirculated water in flotation circuits.