材料期刊网

To recycle residual iron efifciently in Bayer red mud, three-factor three-level orthogonal experiments on carbon-bearing pellets of Bayer red mud were conducted on the basis of their characteristics. The inlfuences of CaO dosage, temperature and roast-ing time on total iron content and iron recovery of reduced iron powder were studied. Results showed that these factors slightly inlfuenced iron recovery, but signiifcantly inlfuenced total iron content. The principal factor inlfuencing total iron content was CaO dosage, followed by temperature and roasting time. An increase in CaO dosage could decrease total iron content, whereas an increase in temperature and an extension of roasting time could improve total iron content. The reduced iron powder with total iron content of 88.41% and iron recovery rate of 97.97% can be obtained under the optimal conditions of temperature of 1 275 °C, roasting time of 60 min and CaO dosage of 7.5%. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses of the reduced pellets showed that iron minerals in red mud were almost completely reduced to metallic iron. The principal factor inlfuencing the total iron content of reduced iron powder was the grain size of metallic iron particles. An increase in CaO dosage hindered the growth of metallic iron particles, whereas an increase in temperature and an extension of roasting time could neutralise the effect of CaO dosage. Therefore, CaO dosage should be decreased when iron minerals in red mud can be adequately reduced into metallic iron.