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Kinetic Mechanisms and Efficient Leaching of Praseodymium, Neodymium, Fluorine, and Lithium from Molten-Salt Slag via Atmospheric Alkaline Leaching

Year: 2025

Type: article

Abstract: Rare-earth molten-salt electrolysis slag contains a substantial quantity of rare-earth elements, rendering it a valuable secondary resource for rare-earth recovery. To achieve the efficient recovery of praseodymium (Pr), neodymium (Nd), lithium (Li), and fluorine (F) from rare-earth molten-salt electrolysis slag, this paper proposes an atmospheric alkaline leaching method. The leaching efficiency of Nd, Pr, F (95.02%), and Li (95.87%) can be reached at a NaOH concentration of 80%, a reaction temperature of 180 °C, a reaction time of 2 h, and an alkali to slag ratio of 3:1. Leaching efficiency kinetic analysis shows that the leaching processes of fluorine and lithium are both controlled by interfacial chemical reactions, with apparent activation energies of 59.06 kJ/mol and 57.33 kJ/mol, respectively. The mineral phase transformation and morphological analysis were studied by X-ray diffractometer and scanning electron microscope. The results indicated that rare-earth fluoride (REF3) reacts with sodium hydroxide to form rare-earth hydroxide (RE(OH)3) and soluble sodium fluoride (NaF), while LiF is converted into LiOH and enters the liquid phase. High-efficiency separation was achieved by washing with water, avoiding high-temperature energy consumption and the problem of fluorine-containing waste gas.

Source: Processes

DOI: 10.3390/pr13041025

Authors: Mingming Yu, Guojun Huang, Tianyong Zhang

Institution: Tianjin University

Language: English

Topic: Molten salt chemistry and electrochemical processes

Subfield: Fluid Flow and Transfer Processes

Field: Chemical Engineering

Domain: Physical Sciences

SDG: Responsible consumption and production

Open Access status: gold

Estimated APC paid: $2,896