文章基本信息

标题：A Molecular-Scale Approach to Rare-Earth Beneficiation: Thinking Small to Avoid Large Losses
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作者：Robert C. Chapleski ; Azhad U. Chowdhury ; Anna K. Wanhala 等
期刊名称：iScience
印刷版ISSN：2589-0042
出版年度：2020
卷号：23
期号：9
页码：1-36
DOI：10.1016/j.isci.2020.101435
语种：English
出版社：Elsevier
摘要：SummarySeparating rare-earth-element-rich minerals from unwanted gangue in mined ores relies on selective binding of collector molecules at the interface to facilitate froth flotation. Salicylhydroxamic acid (SHA) exhibits enhanced selectivity for bastnäsite over calcite in microflotation experiments. Through a multifaceted approach, leveraging density functional theory calculations, and advanced spectroscopic methods, we provide molecular-level mechanistic insight to this selectivity. The hydroxamic acid moiety introduces strong interactions at metal-atom surface sites and hinders subsurface-cation stabilization at vacancy-defect sites, in calcite especially. Resulting from hydrogen-bond-induced interactions, SHA lies flat on the bastnäsite surface and shows a tendency for multilayer formation at high coverages. In this conformation, SHA complexation with bastnäsite metal ions is stabilized, leading to advanced flotation performance. In contrast, SHA lies perpendicular to the calcite surface due to a difference in cationic spacing. We anticipate that these insights will motivate rational design and selection of future collector molecules for enhanced ore beneficiation.Graphical AbstractDisplay OmittedHighlights•Salicylhydroxamic acid (SHA) is an effective collector for flotation of bastnäsite•DFT calculations show that the phenol group anchors SHA flat to bastnäsite surface•Spectroscopic results suggest SHA multilayers on bastnäsite at high coverage•This peculiar adsorption explains efficacy of SHA in bastnäsite flotation from oresChemical Engineering; Spectroscopy; Physical Inorganic Chemistry; Surface Chemistry