CO₂ bubble formation on dolomite surface and its influence on surface wettability and flotation of dolomite

Abstract

Dolomite is a common carbonate mineral that can release CO₂ gas under acidic conditions. The formation of bubbles on the dolomite surface might play a critical role in the flotation separation of dolomite from apatite. In this study, the CO₂ bubbles formation due to CO₂ gas releasing from the dolomite surface under acidic condition was observed using an atomic force microscope (AFM). The influence of CO₂ bubbles on flotation behavior and surface wettability of dolomite was evaluated through micro-flotation test, contact angle measurement and molecular dynamics simulation. The results indicate that no gas phase points were observed on the dolomite surface in deionized water or sodium oleate (NaOL) solution. CO₂ nanobubbles were observed on the dolomite surface treated with NaOL solution at pH 5, with an average size of 44 nm. The presence of CO₂ gas layers has a shielding effect on the adsorption of water molecules on the dolomite surface, potentially enhancing the surface hydrophobicity of dolomite. Therefore, CO₂ bubbles are beneficial for improving flotation recovery of dolomite. This study inspires the idea of utilizing the released CO₂ bubbles in the flotation process of dolomite.