The application and adsorption selectivity of a novel collector 4-butoxy-N-hydroxybenzamide N-hydroxybenzamide in cassiterite flotation

In cassiterite flotation, the superior selectivity of benzohydroxamic acid (BHA) leads to its common use as a collector. However, its weak collecting ability necessitates the synthesis of 4-butoxy-N-hydroxybenzamide (BHBA) by introducing a butoxy group at the para-position of the N-hydroxyamide group in BHA molecular structure. BHBA, when functioning as a collector in the flotation separation of cassiterite and calcite, retains BHA selectivity while enhancing its collecting ability. Zeta potential experiments show that under same reagent dosage and slurry pH conditions, BHBA is adsorbed in larger amounts on cassiterite surface than on calcite, conferring its stronger collecting ability in cassiterite flotation. X-ray photoelectron spectroscopy reveals that BHBA donates more electrons to Sn4+ ions on cassiterite surface versus Ca2+ ions on calcite surface, resulting in the intensified adsorption affinity of BHBA on cassiterite. First-principles calculations indicate that BHBA achieves higher recoveries of cassiterite relative to BHA, attributed to its longer hydrophobic carbon chain and the electron-donating nature of the butoxy group, which enhances the reactivity of the N-hydroxy amide group in BHBA.