Study on the structure-activity relationship of alcohol in ilmenite flotation with benzohydroxamic acid/alcohol as mixed collectors

The structure-activity relationship of alcohol in the synergism between benzohydroxamic acid (BHA) and alcohol as mixed collectors was investigated. Microflotation results showed that an appropriate molecular structure of alcohol was advantageous for ilmenite flotation with BHA/alcohol collectors. In the optimal BHA/1octanol (1-OCT) and BHA/2-octanol (2-OCT) systems, the recoveries of ilmenite were 63.81% and 66.37%, while those of titanaugite were only 12.19% and 13.01%, respectively. The positive synergism was observed in BHA/ alcohol systems at the gas-liquid intersurface and liquid phase. Mixed micelles were formed through hydrogen bonding and van der Waals interactions between BHA and three octanol molecules. At the solid-liquid intersurface, BHA/1-OCT contributed to a significant difference in the surface hydrophobicity between ilmenite and titanaugite. Ilmenite exhibited the strongest surface hydrophobicity in BHA/2-OCT system. As detected by X-ray photoelectron spectroscopy (XPS) measurements and molecular dynamic (MD) simulation, BHA could selectively react with Fe and Pb active sites of ilmenite surfaces through chemisorptions, then 2-OCT co-adsorbed onto the ilmenite surface through hydrogen bonding and van der Waals interactions, increasing the hydrophobicity layer. However, BHA/2-OCT weakly adsorbed onto titanaugite surfaces. The synergism of BHA/alcohol at the gas-liquid-solid intersurface of ilmenite enlarged its hydrophobicity, resulting in the floatability difference between ilmenite and titanaugite.