Novel eco-friendly low cost and energy efficient synthesis of (Nd-Pr-Dy)FeB magnetic powder from monazite concentrate.

Syntheses of NdFeB magnetic powder by conventional method is a complicated multi-step process, which produces harmful pollutants and consumes a huge amount of energy and resources. Herein we report a simple chemical route for the preparation of (Nd-Pr)FeB magnetic powder using monazite concentrate as a precursor. Th, U, Sm, and La impurities were removed from monazite leachate by roasting, solvent extraction and leaching the concentrate. Purified leachate consisting of Nd and Pr Chlorides was added to the FeCl solution, and the solution produced was co-precipitated with NaOH. RE and Fe hydroxide precipitates were converted to the oxides by annealing at 700 °C. Boric acid and CaH were added in the RE and Fe oxides produced, and this mixture was reduced and diffused to (Nd-Pr)FeB. Magnetic properties of the (Nd-Pr)FeB produced were enhanced by introducing antiferromagnetic coupling, induced by Dy addition and efficient removal of CaO byproduct through ball milling in ethanol which increased the BH from 3.9 to 11.45 MGOe. Process reported is energy efficient, environment-friendly, time saving and low-cost.