Reverse flotation of iron ore by a new ternary collector-frother reagent: Fundamentals of adsorption from spectroscopy and molecular modeling

Increasingly complex ores, lithologies, and the need for slimes and tailings reclamation present challenges in the iron industry. The reverse flotation with etheramine collectors and starch depressant as standard approach reached the limits of efficiency for complex ores. This study explores the adsorption of a new ternary surfactant formulation as flotation collector and frother based on a mixture of etheramine, amidoamine and MIBC, on the main minerals in Brazilian iron ore processing, hematite, goethite, quartz and kaolinite. The collector characterization, both in pure form and adsorbed onto minerals, and its components, by Fourier Transformed Infrared (FTIR) Spectroscopy, showed high adsorption onto quartz and kaolinite, low on hematite, and almost null on goethite. Shifts on the characteristic C-H stretching frequencies indicate differences in adsorption modes, supported by quantum calculations. FTIR also shows increased organization of quartz adsorption with coverage. Adsorption configurations from molecular dynamics revealed the organization of adsorbed layers and the difference for kaolinite: the adsorption is mostly on a lying-flat mode even at high coverage. The hydrophobic facet of kaolinite even adsorbs MIBC closely, which points to possible negative effects in flotation processes. These findings aim to enhance the understanding and optimization of flotation processes and similar surfactant applications.