Kinetic study of rare earth elements extraction from decrepitated magnet powder using liquid magnesium

Area of Science:

• Metallurgical Engineering
• Materials Science
• Chemical Engineering

Background:

• Growing demand for rare-earth elements, particularly neodymium, necessitates efficient recycling methods.
• Spent permanent magnets are a significant, yet underutilized, source of rare-earth metals.
• Conventional extraction methods often face challenges in efficiency and environmental impact.

Purpose of the Study:

• To investigate the feasibility of using liquid magnesium for neodymium extraction from decrepitated magnet powder.
• To determine the optimal temperature range and process parameters for efficient neodymium recovery.
• To model the extraction kinetics and extrapolate performance to industrial-scale powder particles.

Main Methods:

• Neodymium extraction was studied by measuring diffusion zone growth in sintered magnet samples immersed in liquid magnesium.
• Experiments were conducted at temperatures ranging from 700 to 900 °C in an agitated reactor.
• The Rosin-Rammler equation was employed to model diffusion zone growth kinetics and estimate particle size distribution.

Main Results:

• Extraction was achieved within a short treatment time, not exceeding 22 minutes, depending on temperature and extraction goals.
• Process temperature and the volume rate setpoint were identified as critical factors influencing extraction efficiency.
• The study successfully simulated neodymium extraction performance on decrepitated magnet powder particles.

Conclusions:

• Liquid magnesium presents a viable and efficient medium for extracting neodymium from spent permanent magnets.
• The process demonstrates potential for industrial application due to its speed and effectiveness at elevated temperatures.
• Further research can optimize parameters for large-scale rare-earth element recovery from magnetic waste.