Study on the Reverse Flotation Separation of Smithsonite from Dolomite Using the Saponified 2-(4,4-Dimethylpentan-2-yl)-5,7,7-trimethyloctanoic Acid as a Collector

Abstract

Dolomite, a prominent calcium-bearing gangue mineral found in carbonate-type zinc oxide ores, poses a significant challenge for effective flotation separation alongside smithsonite due to their highly similar surface properties. The present study explores the potential of 2-(4,4-dimethylpentan-2-yl)-5,7,7-trimethyloctanoic acid (2-DMPT) as a collector for the reverse flotation of smithsonite from dolomite. Micro-flotation experiments indicated that saponified 2-DMPT exhibited superior collecting ability and selectivity for dolomite over smithsonite under highly alkaline conditions. Specifically, the flotation recovery of dolomite reached 62%, whereas only 6% of smithsonite was recovered in the flotation foam products. Zeta potential and attenuated total reflectance–Fourier transform infrared (ATR-FTIR) analysis revealed that changes in pH values had minimal influence on the collector’s adsorption onto dolomite, while significantly hindering its adsorption on the smithsonite surface. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis showed that 2-DMPT could form hydrophobic complexes with the active Ca2+ sites on the dolomite surface at pH 11.5. However, the interaction between smithsonite and carboxylic groups of 2-DMPT under the same conditions was relatively weaker, facilitating their reverse flotation separation. As a result, 2-DMPT shows promise as a potential collector for the reverse flotation process, effectively removing dolomite from smithsonite and reducing acid consumption in subsequent acid-leaching processes.