Ionic atmosphere and temperature field–promoted dissociation and phase reconstruction of bastnaesite

Abstract

Bastnaesite serves as the primary global source mineral for light rare earth elements (LREEs). However, achieving green metallurgy in the rare earth industry still faces severe challenges, including resource wastage, environmental pollution induced by associated fluorine, and low comprehensive recovery rates of REEs. To address the critical issues of green and efficient REE extraction from bastnaesite and the comprehensive utilization of associated fluorine resources, this study proposes a novel coordinated leaching–selective precipitation strategy by introducing an SO₄²⁻ ionic atmosphere and a temperature field. The results demonstrate that during the leaching process, SO₄²⁻ effectively stabilizes [CeF_x]^4−x complexes by forming an ionic atmosphere, thereby retarding the reduction of Ce⁴⁺ and the formation of REF₃. This significantly enhances the leaching efficiency of both non-cerium rare earth elements and total rare earth oxides (TREO leaching rate = 92%). Simultaneously, leveraging phase reconstruction under the temperature field enables regulation of the precipitation transition from [CeF_x]^4−x → CeF₃, achieving a fluorine recovery rate >98% and yielding high-purity CeF₃ (D₅₀ = 1.3–1.9 μm). This process achieves highly efficient separation and extraction of rare earth elements, cerium, and associated fluorine. The proposed ionic atmosphere model provides a reference for developing short-process, green, and clean bastnaesite metallurgy, advancing the sustainable utilization of both rare earth and fluorine resources.