Abstract  

The flotationand adsorption of sodium oleate (NaOL) on spodumene with four differentparticle size fractions (45-75 μm, 38-45 μm, 19-38 μm and 0-19 μm) wereinvestigated. The flotation recovery increases upon slightly decreasing thesize fraction, reaching a peak value at a size fraction of 38-45 μm. Therecovery then decreases gradually upon further decreasing the particle sizeover the entire investigated range of solution pH values. The specificchemisorption sites for the anionic NaOL collector are the Al sites on thesurface of negatively charged spodumene, which is confirmed by FTIR and zetapotential measurements. Anisotropic surface energies and broken bond densitiesare calculated based on density function theory (DFT) to characterize thesurface chemistry of spodumene crystal planes. The anisotropic adsorptionbehavior of NaOL on different crystal planes of spodumene is studied in termsof adsorption conformations and interaction energies by molecular dynamics (MD)simulations. It is demonstrated that NaOL prefers to bind in a monodentatechelating complex configuration to the most stable surface plane, the (110)plane, which has two broken Al-O bonds. The (110) plane of spodumene is morefavorable for chemisorbing NaOL than the (001) plane, which has one broken Al-Obond. The flotation behavior of spodumene with different particle sizes is wellexplained by the surface crystal chemistry. Based on the findings of this work,further improvement in spodumene flotation is possible if a selective comminutionor grinding process is used that favors the production of (110) planes.  

Keywords  

Spodumene; Particle size; Anisotropic adsorption; Flotation; Molecular dynamics