Selective Flocculation Separation of Fine Hematite from Quartz Using a Novel Grafted Copolymer Flocculant

Beneficiation of ultrafine mineral particles (typically with an average size less than 20 µm) remains a critical problem for the mineral processing industry. Selective flocculation technique has been found to show great potential to tackle this problem, whose success mainly depends on the selective adsorption of a flocculant on the target mineral particles. In this work, a novel copolymer flocculant was synthesized by grafting starch and acrylamide, which for the first time, was employed in the flocculation separation of fine hematite from quartz. The composites of the grafted copolymer flocculant (GCF) were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The single mineral flocculation results showed that at the pH of 10–11 and GCF concentration of 125 mg/L, hematite flocs with a compact texture were formed, whose average diameter and fractal dimension reached 36 µm and 2.02, respectively; while quartz flocs were barely observed, and the average diameter of particles stayed at approximately 20 µm. Furthermore, the selective flocculation separation was confirmed in the mixed mineral flocculation. From adsorption tests and zeta potential measurements, it is shown that GCF tended to adsorb more selectively and intensely on hematite surfaces compared with quartz. This study provides a valuable reference for the efficient recovery of fine hematite particles.