Enhancement of 2-hydroxy-3-naphthyl hydroxamic acid adsorption on bastnaesite and monazite surfaces using H2O2 pre-oxidation for improved flotation process

Abstract

Rare earth elements have been widely applied in various sectors. Bastnaesite and monazite are crucial rare earth minerals, and flotation is a vital technique for recovering fine-grained rare earth minerals and separating them from associated gangue minerals such as fluorite and apatite. Flotation collectors play a key role in selectively adsorbing valuable minerals, enhancing their surface hydrophobicity, which has prompted considerable research interest. However, the interaction between minerals and reagents relies on the reactivity and selectivity of the reagent groups, as well as the reactive properties of the surface atoms of the minerals. This study proposes the use of H2O2 oxidation to enhance the flotation process of rare earth minerals. The flotation experiments demonstrated that pre-adding H2O2 before introducing the flotation collector significantly improved the grade and recovery of rare earth concentrates. The adsorption mechanisms of 2-hydroxy-3-naphthyl hydroxamic acid collector on rare earth mineral surfaces before and after H2O2 pre-oxidation were studied. The 2-hydroxy-3-naphthyl hydroxamic acid interacts with Ce3+ on the surface of unoxidized rare earth minerals, forming chelate compounds with five-membered ring structures. The H2O2 exhibited potent oxidizing properties and oxidized the Ce3+ on the bastnaesite and monazite surfaces to more stable Ce4+, which demonstrated stronger binding capability with hydroxamic acid.

Keywords

• Bastnaesite
• Monazite
• Flotation
• H2O2
• Surface pre-oxidation