Recovery of Ferromagnetic Hematite Submicron Particles from Pyrrhotite Ash and Comprehensive Study of Their Structural, Morphological, and Magnetic Properties

The rapid advancement of modern civilization has increased the demand for heavy metals, while the exhaustion of high-grade natural ore supplies compels the investigation of alternate metal sources. Simultaneously, industrial activities cause substantial amounts of inorganic solid waste every year globally, and pyrrhotite ash (PA) represents a notable case for study. PA is an inorganic solid waste produced during the manufacture of phosphoric acid from roasted pyrrhotite ore and contains valuable metals, including Fe. Currently, PA is stored in large open spaces without treatment, posing significant environmental challenges. In response, this study aimed to extract iron oxide particles, identified as a potential raw material for the preparation of new materials. In this work, we develop a full synthesis process of ferromagnetic hematite particles from PA, through acid leaching, followed by a hydrothermal and co-precipitation reaction. Both techniques were effective and led to the production of α-Fe₂O₃ (hematite structure) as confirmed by XRD, SEM, TGA, and Raman spectroscopy techniques, while magnetic properties were determined by using VSM at room temperature. The results revealed that the extracted hematite particles exhibit ferromagnetic behavior.