Recovery of Iron from Pyrite Cinder with Reduction–Magnetic Separation Process in Presence of Sodium Salt

This paper investigated the iron recovery form pyrite cinder with the coal-based reduction–magnetic separation process in the presence of sodium sulfate additive. The functional mechanism of sodium sulfate, reduction behavior of pyrite cinder, and separation mechanism of iron mineral and gangue were investigated through discussing the influences of sodium sulfate dosage, reduction temperature, reduction time, and grinding fineness and analyzing the reduced briquette and magnetic concentrate by using X-ray diffraction, optical microscope and scanning electron microscope and energy-dispersive spectrometer (SEM–EDS). The results show that sodium sulfate can improve the occurrence state and embedded relationship of gangue. Furthermore, the sodium sulfate can promote the interconnection of metallic iron grains, which intensifies the separation of iron mineral and gangue. Under the conditions of pyrite cinder briquette containing 3% Na 2 SO 4 , reducing at 1050 °C for 80 min, the grinding fineness of 76.8% less than 45 μm, and magnetic field intensity of 73 mT, the iron grade of magnetic concentrate and iron recovery rate were 92.02% and 98.63%, respectively.