N-[6-(hydroxyamino)-6-oxohexyl]octanamide: A collector derived from the structure of octyl hydroxamic acid and its application in bastnaesite flotation

Abstract

Bastnaesite has always been faced significant challenges in its flotation separation from its associated gangue minerals like fluorite. Despite being a commonly employed collector for oxide mineral flotations, octyl hydroxamic acid (OHA) still exhibits insufficient selectivity. Consequently, a novel hydroxamic acid, N-[6-(hydroxyamino)-6-oxohexyl]octanamide (NHOO), is synthesized and employed as a collector in bastnaesite flotation, building upon the structure of OHA. Flotation experiments under neutral conditions demonstrate the effective ability of NHOO to achieve a difference of nearly 60% in the recoveries between bastnaesite and fluorite during their separation. Concordant outcomes from zeta potential characterizations, adsorption tests, and X-ray photoemission spectroscopy validate heightened adsorption quantities of NHOO on bastnaesite surface relative to fluorite under identical dosage conditions. Ab initio calculations unveil the capability of NHOO to establish a pentacoordinate chelate ring on bastnaesite surface, whereas on fluorite, it can only form a singular chemical bond. Consequently, NHOO shows a considerably lower energy associated with its adsorption on bastnaesite surface in comparison to its energy on fluorite surface.