铁精矿粉粒度对精控还原工艺的影响

Effect of particle size of fine iron ore concentrate powder on fine control reduction process

本文以河北承德地区的铁精矿粉为原料,选用模拟隧道窑还原工艺制备海绵铁粉,研究了铁精矿粉粒度对精控还原工艺的影响。结果表明：铁精矿粉粒度对其还原工艺影响很大,并直接影响海绵铁粉的产品性能。在既定试验条件下,随着铁精矿粉粒度的增大,其精控还原所需最优还原温度随着增加,最佳配碳量先减少后增大,而最佳还原时间随粒度的增大呈现出先增大后减小的变化趋势。究其原因为粒度过小导致的粉体烧结和粒度过大导致的粉体芯部不易还原均会阻碍还原过程的进行。45~75μm粒度区间铁精矿粉最适合作为制备优质海绵铁粉原料,其在配碳量0.8、还原温度1150℃、还原时间4.5 h的精控还原工艺下可制得的海绵铁粉的铁含量高达97.88%。

Fine iron ore concentrate from Chengde area in Hebei province was selected as raw materials to prepare sponge iron powder by simulation of tunnel kiln reduction process,the effect of the particle size of fine iron ore concentrate powder on fine control reduction process was studied. The results show that the particle size of iron ore concentrate powder has a great influence on the reduction process and the performance of sponge iron powder. The optimum reduction temperature increase with the increase of the particle size of iron ore concentrate powder under a given experimental condition. The optimum reduction time increase firstly and then decrease,but the ratio of coal to fine iron ore concentrate powder show the opposite trend,the reasons are that the finer sponge iron powder reduced from the finer iron ore concentrate powder is prone to be sintered and the bigger iron ore concentrate powder is more difficult to be thoroughly reduced,both hinder the reduction from the iron ore concentrate into sponge iron powder.The iron ore concentrate powder with particle size in the range of 45 μm to 75 μm is very suitable to produce high quality reduced iron powder,and can be used to prepare sponge iron powder with the purity of 97. 88% in the fine control reduction process when the reduction temperature is 1 150 ℃,the reduction time is 4. 5 h and the ratio of coal to fine iron ore concentrate powder is 0. 8.