Insight into anionic and cationic flotation discrepancy of quartz with altered surface roughness by acid etching

Abstract

Surface roughness has a significant effect on mineral flotation. In this study, the surface roughness of quartz was altered using HF etching and their values before and after acid etching were quantified using AFM. Anionic flotation experiments with CaCl2 as activator and sodium oleate (NaOL) as collector, and cationic flotation experiments with dodecyl trimethyl ammonium chloride (DTAC) as collector were carried out for both the raw and acid-etched samples. The results showed that acid etching is beneficial to increase the surface roughness of quartz. The rougher quartz particle has higher recovery and quicker flotation rate during anionic flotation, while lower recovery and slower flotation rate during cationic flotation. The role of surface roughness in the discrepancy of these two flotations was investigated in terms of surface chemistry by X-ray photoelectron spectroscopy, UV spectrophotometer, surface force tensiometer, and zeta potential analyzer. The rougher sample was confirmed to have more unsaturated interfacial active sites, adsorbed more Ca2+ and NaOL, and exhibited higher hydrophobicity in anionic flotation. Differently, the rougher sample was verified to have less interfacial negative charge, adsorbed less DTAC, and exhibited weaker hydrophobicity in cationic flotation. Taken together, the surface roughness altered by acid etching has different effects on the adsorption capacity of NaOL and DTAC, thus affecting the wettability and floatability of quartz particles inconsistently in anionic and cationic flotation.