Surface chemistry features of spodumene with isomorphous substitution

Abstract

Spodumene is an important strategic mineral resource for production of lithium. Froth flotation technology is a major method for recovery of spodumene. Surface chemistry features of minerals have significant effects on flotation performance. Natural spodumene crystals have lattice defects, including isomorphous substitution of Fe, Mn, and Cr. Such substitution will affect surface features, such as hydrophobicity of minerals and collector adsorption on mineral surfaces. In this regard, the influences of lattice substitution on spodumene surface properties were studied with respect to wetting characteristics and collector adsorption using micro-flotation experiments, contact angle measurements, Fourier-transform infrared spectroscopy (FTIR) analysis, molecular dynamics (MD) simulations, and density functional theory (DFT) calculations. Micro-flotation experiments, FTIR analysis, and contact angle results showed that higher Fe contents favored for the oleate adsorption on spodumene surface. Contact angle measurement and MD simulation results revealed that spodumene surfaces with or without substitution were naturally hydrophilic, but the interfacial water structures were expected to be different with various substitutions. Therefore, the interfacial water structure was further analyzed for a better understanding of the wetting of surface. DFT calculations showed that the surfaces with substitution were more in favor of oleate adsorption than the surface without substitution. The surface with Mn substituting for Si was more favorable for the oleate adsorption. It seems that the metal ion sites at surfaces contribute to different interfacial water structures, and lattice substitution plays a significant role in the adsorption state of NaOL.