Exploring the performance of the diamine collector N-Oleyl-1, 3-propanediamine for highly selective reverse flotation of mica from quartz

A new collector, N-Oleyl-1, 3-propanediamine (NOPDA), has strong collecting power and excellent selectivity. • NOPDA achieves effective separation of mica and quartz using a low dosage a 0.016 mmol/L at pH 2.5. • NOPDA preferentially adsorbs onto mica surfaces through hydrogen bonding and electrostatic interactions. • NOPDA is demonstrated as a new flotation collector for the mica surface with high-efficiency separation. The selective separation of mica from quartz remains a significant challenge because of their similar physicochemical properties. In this study, a cationic diamine collector, N-oleyl-1,3-propanediamine (NOPDA), was evaluated for the flotation separation of mica from quartz under acidic conditions. Single-mineral flotation results demonstrated a substantial recovery difference of approximately 84%, with mica recovery reaching 95%, whereas quartz recovery remained low (10.91%) at pH 2.5, indicating a strong selectivity. Mixed-mineral flotation further confirmed effective separation, yielding a concentrate enriched in mica-associated components, including Al 2 O 3 (33.05%, 94.41% recovery) and K 2 O (11.39%, 98.46% recovery), with a relatively low SiO 2 recovery (32.50%). The flotation mechanisms were analyzed through zeta potential testing, contact angle, zeta potential, FTIR, and XPS analyses, which revealed that NOPDA preferentially adsorbs on mica surfaces, significantly enhancing hydrophobicity, whereas only weak interactions were observed on quartz. The adsorption mechanism is primarily attributed to the electrostatic attraction and hydrogen bonding of the protonated amine species with the surface Al–O and Si–O sites of the adsorbent. Density Functional Theory (DFT) calculations indicated that the adsorption energy difference between NOPDA on mica and quartz was 2.75 eV, which is consistent with the flotation results. Overall, these findings demonstrate that NOPDA exhibits promising selective flotation performance for mica–quartz separation under acidic conditions. The combined flotation experiments, surface characterization, and DFT analysis provide insights into the preferential adsorption behavior of NOPDA on the mica surface. Download: Download high-res image (175KB) Download: Download full-size image