Cost-effective integrated strategy for the fabrication of hard-magnet barium hexaferrite powders from low-grade barite ore

Abstract

Ultrafine barium hexaferrite (BaFe12O19) powders were synthesized from the metallurgical extracts of low-grade Egyptian barite ore via a co-precipitation route. Hydrometallurgical treatment of barite ore was systematically studied to achieve the maximum dissolution efficiency of Fe (~99.7%) under the optimum conditions. The hexaferrite precursors were obtained by the co-precipitation of BaS produced by the reduction of barite ore with carbon at 1273 K and then dissolved in diluted HCl and FeCl3 solution at pH 10 using NaOH as a base; the product was then annealed at 1273 K in an open atmosphere. The effect of Fe3+/Ba2+ molar ratio and the addition of hydrogen peroxide (H2O2) on the phase structure, crystallite size, morphology, and magnetic properties were investigated by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. Single-phase BaFe12O19 powder was obtained at an Fe3+/Ba2+ molar ratio of 8.00. The formed powders exhibited a hexagonal platelet-like structure. Good maximum magnetization (48.3 A·m2·kg–1) was achieved in the material prepared at an Fe3+/Ba2+ molar ratio of 8.0 in the presence of 5% H2O2 as an oxidizer and at 1273 K because of the formation of a uniform, hexagonal-shaped structure.