Pyrite as an efficient reductant for magnetization roasting and its efficacy in iron recovery from iron-bearing tailing

Abstract

The over-reduction of Fe2O3 in iron-bearing tailing during magnetization roasting is one of the main obstacles for the application of magnetization roasting with coal reductants. It is of great importance to explore suitable reductants for the magnetization roasting to recover iron form the tailing. In this paper, we developed pyrite as a reductant for the magnetization roasting and it was used to recover iron form iron-bearing tailing. Here, we show that addition of pyrite during the magnetization roasting process remarkably hindered the over-reduction of Fe2O3 to FeO and promoted the formation of Fe3O4. The experimental results confirmed, magnetization roasting with pyrite as reductant, the concentrate with an iron grade of 61.03% and iron recovery of 94.70% were obtained, under the roasting temperature of 800℃, pyrite addition of 1.0 g, tailing addition of 16.0 g and roasting time of 30.0 min, nitrogen flow rate of 100.0 mL/min, magnetic field intensity of 130.0 kA/m and magnetic separation time of 10.0 min. In addition, a possible reaction mechanism between FeS2 and Fe2O3 was proposed based on thermodynamic, thermogravimetric, X-ray diffraction analysis and experimental validation. The results of this research confirmed that pyrite is an effective and environment-friendly reductant for the magnetization roasting to recover iron from iron-bearing tailing.