# Production of Nd and Nd–Fe Alloys from NdCl3 by Calciothermic Reduction

## TL;DR

This paper introduces a new method to produce neodymium and neodymium-iron alloys at lower temperatures with high recovery rates.

## Contribution

A novel calciothermic reduction process using thermodynamic optimization to improve neodymium recovery and energy efficiency.

## Key findings

- Nd recovery rate reached 97.0% at 1050 °C using 1.2× stoichiometric Ca.
- Nd–Fe alloys with 96.3% recovery were produced at 1050 °C for eutectic compositions.
- Lowering temperature to 850 °C reduced Nd recovery to 89.8%, suggesting energy-efficient production potential.

## Abstract

This study presents a metallothermic reduction mechanism for fabricating Nd and Nd–Fe alloys at 850–1050 °C using anhydrous NdCl3 and Ca, which have relatively low melting points. Our method decreased the process temperature while improving the recovery rate of Nd using the thermodynamic parameters of the CaCl2–KCl–NaCl and Nd–Fe liquid solutions. To reduce the activity of the product (CaCl2), the optimal composition of the CaCl2–KCl–NaCl molten salt was XCaCl2=0.4 (XKCl:XNaCl=6:4). The molten metal bath (Nd or Nd–Fe) that formed at the bottom of the reaction zone during Nd and Nd–Fe alloy production absorbed metal particles generated in the molten salt during the reaction, thereby facilitating ingot formation. In Nd produced at 1050 °C using 1.2× the stoichiometric amount (by mass) of Ca, the Nd recovery rate was 97.0%. Moreover, in the Nd–Fe alloys produced at 1050 °C targeting eutectic compositions, the Nd recovery rate was 96.3%. Increased Fe contents in the Nd–Fe liquid solution reduced the Nd recovery rates, and the Nd–Fe alloy (Nd recovery rate: 89.8%) was produced at 850 °C, suggesting the possibility of increasing the energy efficiency of the Nd production process. The Nd–Fe alloy produced through this proposed process could be used as a raw material in the NdFeB strip casting process.