Separation of hematite and quartz in a cationic collector flotation system using Pullulan as a greener depressant.

• Pullulan was a green and efficient depressant of hematite in DDA reverse flotation. • Pullulan could enhance the hydrophilicity of the hematite surface. • Pullulan could adsorb on hematite surface through hydrogen bonding and chemical bonds. As the uncertainly of climate and the world situation intensifies, there are more and more pressures on resources and environment faced by human beings, the requirements for the development of mineral resources have become higher and higher. Iron mineral, as the most exploited mineral by mankind at present, the green and efficient purification of iron ore is an important means to realize energy saving and carbon reduction. In this paper, a novel hematite depressant—Pullulan (an environment friendly microbial polysaccharide, represented as PU thereafter), was introduced into the purification of hematite from quartz in cationic collector flotation system. Furthermore, a serious of surface tests were applied to explore the adsorption mechanisms between PU and the mineral surfaces. According to these experiments, it can be concluded as follows. The results of micro-flotation exhibited that PU showed better inhibition for hematite in DDA flotation system, the concentrate product with Fe grade of 65.88 %, and 91.06 % recovery was obtained from the artificial mixed minerals at 20 mg/L DDA, 15 mg/L PU at natural slurry pH. Wettability analysis suggested that PU could enable the hematite surface to become more hydrophilic, while little effect on wettability changes were observed on the quartz surface. The zeta-potential, FTIR and XPS analyses revealed that PU could occur adsorption on the hematite surface relying on hydrogen bonding with the hydrated hematite surface, and chemical complexation formed between the hydroxyl groups on PU and the Fe sites of the hematite surface. [ABSTRACT FROM AUTHOR]