NdFeB End-to-End Process: From Mining to Magnetization
A full technical walkthrough of sintered NdFeB — from mining and separation to magnetization and recycling.
Sintered NdFeB is the highest-performing permanent magnet material widely used today. Its manufacturing is a tightly coupled end-to-end process where each step directly impacts stability and quality.
Mining
Extract and beneficiate rare-earth ore to concentrate RE minerals and remove gangue/impurities. REO content raised to ~60%+.
Solvent Extraction
Multi-stage counter-current solvent extraction separates target REs (e.g., Nd) — industrial standard for high-purity separation.
Calcination
Heat Nd intermediates to remove volatiles and form Nd₂O₃ powder for electrolysis.
Molten Salt Electrolysis
Reduce Nd ions to metallic Nd under high temperature in an inert atmosphere.
Strip Casting
Vacuum induction melt Nd-Fe-B alloy and rapidly quench on a rotating copper wheel to produce thin alloy flakes (~0.3 mm).
HD & Jet Milling
Hydrogen decrepitation embrittles the alloy along grain boundaries, followed by jet milling to ~3–5 μm powder.
Pressing & Sintering
Align powder in a magnetic field and compact; then vacuum sinter (~1000–1100°C) to densify.
Machining
Diamond grinding, wire-cutting, and precision machining to final dimensions.
Surface Treatment
Plating/coating (e.g., Ni-Cu-Ni, electroless, epoxy) builds corrosion protection.
Magnetizing
Apply high pulsed fields to saturate magnets; axial, radial, or multipole patterns available.