One-Step Direct Reduction of Damp Milled Magnetite Concentrate Pellets

The direct reduction of magnetite pellets of 69.21%-70.86% Fet, was conducted.The pellets were made from damp milled concentrate to increase strength of green balls, lower binder dosage and reduce fines generated during drying and handling dried balls.For the magnetite concentrate pretreated by damp milling for 4 min and ba-lling at 7.2% moisture for 15 min,the drop number of green balls were increased from 3.8 times to 13.7 times from 0.5 meters and fines fraction of dried balls was reduced from 10.98% to 2.98%, respectively.The compressive strength of pellets preheated at 800 ℃ for 10 min was raised from 466 Newton to 581 Newton, while the metallization degree was almost the same compared with that made from magnetite concentrate prepared without damp mi-lling.The pilot direct reduction was performed to stimulate grate-kiln process. The results are as follows: Fet of DRI 93.91%,metallization degree 95.99%, sulphur content lower than 0.01%, magnetic powder rate 0.75%-0.96% and reductant coal rate 808.5-859.3 kg/t.Such DRI is a high quality charge for electric arc furnace steel making.