The adsorption of sodium oleate and potassium octyl-hydroxamate onto t
he rare-earths minerals monazite and bastnaesite was investigated thro
ugh microflotation experiments, zeta potential determinations and infr
ared spectroscopy. The monazite and bastnaesite samples were purified
in the laboratory reaching, respectively, final grades of 68.7 and 45.
3% RE(2)O(3) + ThO2. The results confirm that sodium oleate chemisorbs
onto bastnaesite and suggest a physical adsorption mechanism of this
reagent onto monazite. Despite the lack of a full confirmation from FT
IR spectrometry, there is a possibility of oleate chemisorption onto m
onazite in the pH range above the isoelectric point. A chemical adsorp
tion mechanism was established for the interaction between octyl-hydro
xamate and both minerals.