Abstract: To address the issues of high dosage and insufficient selectivity of the hydroxamic acid collector No. 8 in the
flotation process of Bayan Obo rare earth ore,this study investigated the synergistic effect and mechanism of an environmentally
friendly ether surfactant BS-03. The effects of the BS-03 and hydroxamic acid combined system on the flotation behavior of rare
earth minerals were examined through actual ore flotation tests,single mineral flotation tests,Zeta potential measurements,adsorption
capacity determination,and XPS analysis. The results show that using BS-03 as a combined reagent under flotation
conditions of pulp concentration of 40%,temperature of 55~60 ℃,pH = 8. 5,sodium silicate at 0. 75 kg/ t,8# reagent at 1. 5
kg/ t,and BS-03 at 0. 15 kg/ t,an open-circuit flotation process consisting of one roughing stage and three cleaning stages yields
a rare earth concentrate with a REO grade of 55. 85% and a REO recovery of 55. 14%. BS-03 significantly enhanced the collecting
ability of benzohydroxamic acid (BHA) for bastnaesite,increasing the recovery to 93. 9%. Mechanism analysis indicated
that BS-03 promoted both chemical and physical adsorption of BHA on the bastnaesite surface,resulting in a larger negative
shift of Zeta potential,increased surface adsorption capacity,and improved pulp and froth properties. Therefore,BS-03 is an effective
synergist for rare earth flotation,capable of reducing the dosage of hydroxamic acid and improving separation performance.