低品位铁矿石煤基回转窑直接还原研究

Study on Coal-based Direct Reduction of Low-grade Iron Ore with Rotary Kiln

以低品位块矿为原料,褐煤半焦为还原剂,进行直接还原研究.在温度为1100℃,还原时间为1.5h,还原剂配量为30%~40%,可获得金属化率为85%以上的直接还原铁.在煤基回转窑中,加入40%配比量的褐煤可获得与30%半焦加入量相同的金属化率.回转窑实验所得平均金属化率较低,仅为70.44%,这主要是由于窑温分布不均匀,高温区停留时间短,还原产品空冷等情况造成的.如若温度控制得当,还原时间充足,还原铁密闭降温,金属化率可达到80%以上.

Direct reduction of iron in low-grade iron ore with addition of wood coal as reducing agent was studied. Based on the experimental results in laboratory, it was available for more than 85% DRI when the temperature was at 1100 ℃, reduction time 1.5 h and amount of reducing agent from 30% to 40%. Using added block ore and 40% ratio of brown coal, the same metallization rate could be obtained as that with 30% ratio of semi-coke in the rotary kiln. The average metallization rate, which was only 70.44% in the experiment of rotary kiln, was low due to the uneven distribution of temperature, short residence time in high temperature zone and air-cooling reduced products. Given the properly controlled temperature, adequate reduction time and sealed reduction condition, the metallization rate could reach 80%.