Biodepressant based on thiol silylated cellulose nanocrystals: Insights into behavior in a binary mineral system of chalcopyrite and pyrite

The selective separation of chalcopyrite and pyrite presents a critical challenge in froth flotation technology because of their similar surface properties. In a prior study, thiol-containing cellulose nanocrystals (thiol-CNCs) were identified as efficient biogenic chalcopyrite depressants in single mineral systems when used with the sodium isobutyl xanthate (SIBX) collector. In this study, we investigated the efficacy of thiol-CNCs as biodepressants in a binary system of chalcopyrite and pyrite employing an agitated microflotation cell, with a focus on selectivity and depression mechanisms. Thiol-CNCs demonstrate high depression efficiency for chalcopyrite at low concentrations in single-mineral systems. However, in binary systems, the depressant exhibited limited selectivity, attributed to chalcopyrite-induced copper activation on pyrite surfaces. Colloidal probe atomic force microscopy (CP-AFM) measurements further confirmed that thiol-CNCs decrease SIBX adsorption on chalcopyrite surfaces, leading to reduced adhesion forces. This study offers valuable insights into the application of nanocellulose-based depressants for improving sustainable flotation processes.