Separation of Iron and Rare Earths from Low-Intensity Magnetic Separation (LIMS) Tailings through Magnetization Roasting-Magnetic Separation.

Low-intensity magnetic separation tailings (LIMS tailings) are a common by-product obtained after magnetite magnetic separation. In this article, various techniques such as chemical analysis, X-ray diffraction, ICP-MS, and Mineral Liberation Analysis (MLA) were employed to investigate the LIMS tailings. The primary iron-bearing mineral identified was hematite and rare earth minerals were monazite and bastnaesite. The main gangue species was fluorite with small amounts of dolomite and amphibole. Due to the weak magnetism of hematite and rare earth minerals, magnetic separation has low efficiency. However, magnetization roasting-magnetic separation is an effective method to recover hematite. The present study focuses on the separation of iron and rare earth from LIMS tailings through magnetization roasting-magnetic separation. The results demonstrate that with a roasting temperature of 650 °C, a roasting time of 60 min, a slurry concentration solid-liquid ratio of 25 : 1, a rough magnetic field intensity of 0.16 T, and a selected magnetic field intensity of 0.10 T, the iron grade in the magnetic concentrate increases to 65.49 % and an iron recovery rate of 65.16 % can be achieved. The XRD patterns of magnetic separation concentrate show that the main mineral phases in concentrate are magnetite (Fe3 O4 ) and fluorite (CaF2 ), which can be removed by grinding and reverse flotation fluorite to obtain a high-grade iron concentrate. The REO grade of magnetic separation tailings is 11.98 %, and its recovery rate is 97.96 %. Consequently, rare earth can be effectively extracted and separated after the subsequent flotation-leaching process.

The Effect of Oleic Acid Emulsification using SPE on Fluorite and Dolomite Flotation.

Collector OA, oleic acid, is widely used industrially for fluorite flotation. Low selectivity, dispersibility and collecting capability of the OA collector are always observed. In this study, compared with flotation of dolomite, a collector mixture of OA and SPE (styrylphenol polyoxyethylene ether) demonstrated significantly better performances for the fluorite. An optimal mass ratio 4 : 1 OA : SPE was found, and the recovery of fluorite was increased from over 85 % to more than 94 % compared with pure OA. Furthermore, the dosage of the collector agent was reduced from 50  mg mL-1 to 20 mg mL-1 , which did not negatively impact the recovery of dolomite. The results from the contact angle tests indicated that SPE selectively increased the surface hydrophobicity of fluorite but had little effect on dolomite. Besides, zeta potential measurements and IR analyses revealed that the addition of SPE led to strong chemical adsorption on the surface of fluorite, resulting in a significant difference in the flotation performances of the two minerals. Therefore, SPE-emulsified OA is corroborated to prompt more selectivity and collecting capability on flotation of fluorite over dolomite.