Abstract: The reduction roasting method is often used in the process of iron separation in Bayan Obo mine. During the roasting process,the phase transformation of rare earth minerals will occur and affect its flotation behavior. In this paper,the physical phase changes of cerium fluorocarbon (Cerium fluoride) after roasting at 400,450,500,550 ℃ and the effects of the flotation behaviour of Cerium fluorocarbon (Cerium fluoride) and roasted Cerium fluorocarbon (Cerium fluoride) at 500 ℃ under the action of two trappers,octyl hydroxamic acid (OHA) and diethylhexyl phosphate (2ZHP),were investigated by means of XRD analytical tests,SEM-EDS tests,flotation tests,contact angle tests,kinetic potential tests of mineral surfaces,and X-ray photoelectron spectroscopy (XPS) analyses. XRD and SEM-EDS test results show that REFCO3 is obtained when calcined at 450 ℃,RE3O4F3 is partially decomposed when calcined at 500 ℃,and RE3O4F3 is completely transformed when calcined at 550 ℃. The collector OHA has poor flotation effect on the new substance RE3O4F3 produced by the calcination of cerium fluocerite at 500 ℃,The contact Angle test showed that 2ZHP could strengthen the surface hydrophobicity of bastnaesite and roasting bastnaesite at 500 ℃. Zeta potential test showed that compared with OHA,2ZHP could adsorb bastnaesite more effectively. XPS test showed that OHA and 2ZHP played a trapping role through mineral surface adsorption. However,the adsorption capacity of 2ZHP on the surface of calcined bastnaesite is greater. while the collector 2ZHP has the same collecting capacity for REFCO3 and RE3O4F3 produced by the calcination of cerium fluocerite at 500 ℃. 2ZHP is more suitable for the flotation of cerium fluoride after roasting.

Key words: roasted bastnaesite,phase transformation,flotation,octyl hydroxamic acid,diethylhexyl phosphate