A micro-scale investigation of the adsorption of collectors on bastnaesite

A micro-scale investigation was carried out by applying an atomic force microscope (AFM) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to study in situ the adsorption of three different collectors - oleic acid, octanohydroxamic acid (HA) and salicylhydroxamic acid (SHA) - on bastnaesite in aqueous solutions. The results show that all three collectors adsorb on bastnaesite. The hydroxamic acid collectors - HA and SHA - adsorb on bastnaesite mainly in the form of insoluble metal hydroxamate. Their specific adsorption mechanism indicates that high selectivity will be achieved with a hydroxamic acid collector for the flotation of bastnaesite. Background Despite using froth flotation to treat the bastnaesite ore at the Mountain Pass Mine, rare earth oxide (REO) recovery is still low [1,2], which is believed to be due to the low selectivity of the collector, oleic acid. To raise the flotation selectivity, the pulp in the mine circuit has to be heated to 70 to 90 °C, resulting in high energy consumption, and large quantities of depressants have to be added. The search for a novel collector for bastnaesite is therefore called for to improve flotation performance [2]. In the present study, in order to explore the underlying mechanism of the flotation process, such as the mechanism of collector adsorption on the bastnaesite surface, AFM and ATR-FTIR were used to study the adsorption behavior of collectors on the bastnaesite surface. The information is important for the development of a new flotation scheme for bastnaesite.