A new process for high-efficiency rare earth enrichment in Baiyun Ebo metal ores: a synergistic optimization study of open-circuit flotation, closed-circuit flotation of the middle ore and magnetic separation

Abstract

To address the low utilization rate of rare earth resources in the Bayan Obo mining area of Baotou, Inner Mongolia, China, a systematic experimental study was conducted using a novel combined process of “open-circuit flotation – closed-circuit flotation of middlings – magnetic separation”. The mechanism of depressant BY5 on mineral surfaces was investigated through Fourier Transform Infrared Spectroscopy (FTIR) analysis and Ultraviolet-Visible (UV) spectrophotometric adsorption capacity tests. The results demonstrate that under the conditions of grinding fineness 95% passing 74 μm, flotation temperature 65°C, pulp concentration 45%, and pulp pH 9, using BY5 as depressant, BQ2 as collector, and terpineol as frother, an open-circuit flotation concentrate with a grade of 62.07% and recovery of 43.80% was obtained through “one roughing, one scavenging, and four cleaning” stages. For the rare earth middlings, with grinding fineness 95% passing 38 μm and optimized reagent dosage, subsequent “one roughing and four cleaning” flotation tests followed by “one roughing and one scavenging” magnetic separation tests yielded an open-circuit magnetic separation concentrate with a grade of 58.07% and operational recovery of 85.74%. The combined concentrates showed an overall yield of 10.62%, a grade of 61.09%, and a recovery of 57.15%. Depressant BY5 exhibits non-chemical adsorption on bastnaesite surfaces, while collector BQ2 undergoes chemical adsorption. BY5 competes with BQ2 for adsorption sites on fluorite and barite surfaces, thereby hindering BQ2 adsorption on these gangue minerals and achieving effective separation of bastnaesite from fluorite and barite.