<p>Due to its high selectivity, benzohydroxamic acid (BHA) is widely recognized for its role as a collector in oxidized mineral flotation. Despite its utility, BHA has the disadvantage of insufficient collecting ability. This paper introduces a novel collector, 4-butoxy-benzohydroxamic acid (BBHA), which extends the carbon chain by adding a butoxy group at the para site of the N-hydroxy amide group in the BHA molecule. BBHA is expected to exhibit stronger collecting ability than BHA. Flotation experiments show that the selectivity of BHA is maintained in BBHA, alongside an improvement in its collecting ability in the flotation separation of bastnaesite and fluorite. Zeta potential measurements indicate that, at identical doses, BBHA binds to bastnaesite surface significantly more than to fluorite, resulting in a stronger collecting ability for bastnaesite. Consequently, BBHA shows improved selectivity in flotation. X-ray photoelectron spectroscopy reveals that, when BBHA adsorbs on bastnaesite and fluorite surfaces, Ce³⁺ ions on bastnaesite acquire more electrons from BBHA than Ca²⁺ ions on fluorite, resulting in stronger chemical bonds between BBHA and bastnaesite, and significantly more BBHA adsorption on the bastnaesite surface under the same conditions. This paper provides theoretical support for the application of BBHA and offers empirical reference for the design of novel collector molecules.</p>