Coproduction of DRI powder and semi-coke from siderite ore and low rank coal by excessive coal-based direct reduction in rotary kiln

Abstract

Effective utilization of low grade iron ore and low rank coal by excessive coal-based direct reduction process to coproduce DRI powder and semi-coke can be one of the solutions to cut the high cost of DRI powder and solve the problem of DRI shortage in the steelmaking industrial in China. In this paper, an integrated process was developed to beneficiate low grade siderite ore and upgrade inferior coal simultaneously to yield DRI powder and semi-coke. Based on bench scale results, the pilot scale verification tests were conducted and the final DRI concentrate assaying 92.62% Fetotal, 93.51% metallization degree was obtained at total iron recovery of 82.98%. Meanwhile, C/Fe mass ratio was elevated to 2.50 in the direct reduction of siderite to generate semi-coke as by-product, which contained 76.11% fixed carbon. Based on the characterization of the semi-coke, it can be used as solid fuel in the iron ore sintering to replace coke breeze and cut production cost. The integrated process provides an attractive way to manufacture good quality burdens for electric furnace and alternative solid fuel for metallurgy industry.