Recovery of iron from pyrite cinder by suspension magnetization roasting-magnetic separation method: Process optimization and mechanism study

Pyrite cinder (PyC) is an iron-enriched tailing.Suspension magnetization roasting(SMR) technology can convert hematite into magnetite, the magnetic properties of the product have been improved, and then through the magnetic separation to complete the separation of magnetite and gangue. SMR consumes less energy than the direct reduction process to obtain Fe(M).SMR-magnetic separation is utilized to effectively exploit the iron in PyC. The results showed that the raw ore for PyC has an iron grade of 56.47%, and after SMR-magnetic separation, magnetic concentrate with an iron grade of 63.24% and an iron recovery of 95.05% could be achieved under conditions of a roasting temperature of 480 degrees C, a reductant concentration of 30% (CO: H2 = 1:3), a roasting time of 20min, 1200Oe magnetic field intensity, and a finesse of grinding content of -0.038mm 80%. The analyses of the process mechanism were performed using X-ray diffraction (XRD), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy as well as fully automatic specific surface and porosity analyzer BET. It was revealed that the transformation of hematite to magnetite took place during the suspension magnetization roasting process, which also contributed to the generation of cracks and pores that led to the increase of specific surface area, total pore volume and average pore diameter.