An ion-tolerance collector AESNa for effective flotation of magnesite from dolomite

The separation of magnesite and dolomite has always been a difficult problem in flotation production, one of the reasons is that the dissolved Ca2+ ions from dolomite weaken the anionic flotation selectivity. In this study, an ion-tolerance collector, sodium fatty alcohol polyoxyethylene ether sulfonate (AESNa), was used to weaken or eliminate the adverse effects of Ca2+. Micro-flotation tests, surface tension tests, Fourier transform infrared spectroscopy (FTIR) tests, X-ray photoelectron spectroscopy (XPS) tests, and density functional theory (DFT) calculations were carried out. The micro-flotation results showed that AESNa had a better collecting ability and selectivity under alkaline conditions, and the addition of Ca2+ selectively inhibited approximately 15% recovery of dolomite. Additionally, AESNa successfully separated magnesite from dolomite in the presence of Ca2+ and water glass (Na2SiO3) for the first time. The mechanism analysis indicated that AESNa had a high surface activity and was chemically adsorbed on the mineral surface. The EO groups in AESNa complexed with Ca2+ by electrostatic interactions and made it difficult for Ca2+ to invade polar head groups, resulting in the flotation of magnesite not being affected. Additionally, the interaction between the sulfonic groups and CaOH+ was weak and led to inhibition of the adsorption of AESNa on the surface of dolomite by a large amount of CaOH+. Therefore, AESNa can promise a wide range of application prospects in flotation production, and the ion tolerance of the collector becomes a key factor in improving the flotation selectivity of soluble minerals.