Novel alkyl bis(hydroxycarbamoyl) propionic acids for flotation separation of diaspore against aluminosilicate minerals

Abstract

Novel chelating reagents containing mono-carboxyl and double-hydroxycarbamoyl group were designed and synthesized as collector, such as 3,3-bis(hydroxycarbamoyl) undecanoic acid (BHUA), 3,3-bis(hydroxycarbamoyl) tridecanoic acid (BHTA) and 3,3-bis(hydroxycarbamoyl) pentadecoic acid (BHPA). These collectors were investigated to float single minerals, artificially mixed minerals and real diasporic bauxite ore. The collecting performance on minerals was interpreted by means of adsorption amount measurement, X-ray photoelectron spectroscopy analysis, zeta potential measurement and density functional theory (DFT) calculation. The appropriate pH value for the diaspore flotation are close to neutral pH value at which diaspore presents quite good floatability while kaolinite and illite exhibit very poor floatability. The satisfactory results on the mass ratio of Al2O3 to SiO2 and the Al2O3 recovery were obtained for the flotation separation of artificially mixed minerals and diasporic bauxite using BHUA as collector, demonstrating the high selectivity of BHUA for the flotation separation of bauxite. The O atoms in these collectors possess more negative charges and more easily donate electrons than N atoms, and surface Al atoms on diaspore are more than those on aluminosilicate minerals, causing diaspore adsorbing reagent in larger amount than aluminosilicate minerals and resulting in high selectivity for minerals flotation.