During the flotation separation process of bastnaesite, it is difficult to separate bastnaesite from fluorite effectively. In this present study, sodium silicate (SS) can effectively improve the flotation separation effect of bastnaesite and fluorite in salicylhydroxamic acid (SHA) systemasa. Through relevant analyses, such as Zeta potential measurements, adsorption capacity tests, Fourier transform infrared (FTIR) spectroscopic analyses and X-ray photoelectron spectroscopy (XPS) tests, the selective suppressor of SS on fluorite was proven. At pH 10, the single mineral flotation results show that with the increase of SS dosage, the flotation recovery of fluorite rapidly decreases from 61.5% to 35.31%, while the flotation rate of bastnaesite is still high (recovery is 80.02%). Then, the experiment of artificial mixed ore proved that the flotation separation of fluorite and bastnaesite was effective under the appropriate dosage of inhibitor. The results of potentiodynamic measurement and an adsorption capacity test showed that the structure of SS more easily reacted with fluorite, which further prevented the adsorption of SHA on the fluorite surface. FTIR test results and XPS analysis further showed that SS had a strong binding effect with the Ca site on the fluorite surface, but a weak binding effect with the Ce site on the bastnaesite surface. Consequently, SS can be used as an effective inhibitor in the flotation separation of fluorite and bastnaesite.

In this study, 2-hydroxy-3-naphthalene hydroxamic acid (NHA) was used as a collector in microflotation experiments. By comparing the flotation performance of NHA with that of sodium oleate (NaOL) and salicylhydroxamic acid (SHA) commonly used in industry, the performance of NHA in the flotation separation of bastnaesite and calcite was studied. Potentiodynamic (zeta) measurements, Fourier transform infrared spectroscopy (FTIR) measurements and X-ray photoelectron spectroscopy (XPS) measurements were used to reveal the interaction mechanism of bastnaesite with NHA. The results of the pure mineral microflotation test showed that when the pH value was 9 and the dosage of NHA was 4.0 × 10−4 mol/L, the recovery of bastnaesite reached 93.5%. A concentrate with a bastnaesite grade of 87.08% was obtained from the flotation test of artificially mixed ore, and the recovery of bastnaesite was 90.83%. The zeta measurements and FTIR experiments showed that NHA adsorbed onto the surface of bastnaesite, which changed the surface state of bastnaesite. XPS testing showed that NHA chemically adsorbed onto the bastnaesite, and Ce3+ formed a chelated structure with −C(OH)=NO−. The hydrophobicity of the surface of bastnaesite was improved, which made it easier for bastnaesite to adhere to the slurry surface by bubbles. At present, most of the domestic methods for recovering fine-grained bastnaesite use flotation recovery. Calcite and other gangue minerals inevitably enter into the concentrate resulting in low-grade REE concentrate.