Preparing high-purity iron by direct reduction‒smelting separation of ultra-high-grade iron concentrate

Abstract

A new process for preparing high-purity iron (HPI) was proposed, and it was investigated by laboratory experiments and pilot tests. The results show that under conditions of a reduced temperature of 1075°C, reduced time of 5 h, and CaO content of 2.5wt%, a DRI with a metallization rate of 96.5% was obtained through coal-based direct reduction of ultra-high-grade iron concentrate. Then, an HPI with a Fe purity of 99.95% and C, Si, Mn, and P contents as low as 0.0008wt%, 0.0006wt%, 0.0014wt%, and 0.0015wt%, respectively, was prepared by smelting separation of the DRI using a smelting temperature of 1625°C, smelting time of 45 min, and CaO content of 9.3wt%. The product of the pilot test with a scale of 0.01 Mt/a had a lower impurity content than the Chinese industry standard. An HPI with a Fe purity of 99.98wt% can be produced through the direct reduction?smelting separation of ultra-high-grade iron concentrate at relatively low cost. The proposed process shows a promising prospect for application in the future.