【摘要】 以铁品位为69.21%(质量分数)的磁铁精矿为原料,采用预热球团"一步法"煤基直接还原工艺制取直接还原铁。为了降低该精矿成球时产生过多粉末,采用润磨工艺来预处理混合料,并在最优条件下进行了扩大型全流程试验。研究结果表明:在磁铁精矿配加1.0%复合粘结剂及润磨4 min的条件下,生球落下强度由未润磨时的3.8次/(0.5 m)提高到13.7次/(0.5 m);润磨后干球(<1 mm=粉末率由未润磨时的10.98%降低到2.98%;在预热温度为800℃和预热时间为10 min时,预热球团抗压强度由未润磨时的466 N/个提高到581 N/个。预热球团直接还原时,采用润磨预处理方案球团的金属化率与无润磨工艺球团的金属化率相差不大,但金属化球团抗压强度远远大于未润磨时的金属化球团抗压强度,且几乎不产生磁性粉末。通过链箅机-回转窑直接还原扩大试验,所得直接还原球团铁品位达93.43%,金属化率达95.88%,含硫量低于0.01%,磁性粉率为0.75%~0.96%,每吨直接还原铁所耗还原煤为808.5~859.3 kg。更多还原

【Abstract】 The coal-based one-step direct reduction of magnetite concentrate,assaying 69.21%(mass fraction) total Fe,was conducted,where damp milling was utilized to pretreat the concentrate for increasing green balls strength,lowering binder dosage and reducing fines generated during drying and handling dried balls.The results show that with magnetite concentrate pretreated by damp milling for 4 min drop number of green balls increases from 3.8 times to 13.7 times from 0.5 m height,and fine fraction of dried balls reduces from 10.98% to 2.98%,when compared with that without pretreating magnetite concentrate before balling.The compressive strength of preheated pellets rises from 466 N to 581 N per pellet with the magnetite concentrate pretreated by damp mill and preheating pellets at 800 ℃ for 10 min.The metallized pellets made of magnetite concentrate pretreated by damp milling possess higher compressive strength than that without damp milling,while the metallization degree is close to each other.Based on small scale tests,pilot tests of direct reduction are performed to stimulate grate-kiln process.Main results are as follows: 93.43% total Fe of directly reduced iron(DRI),95.88% metallization,sulphur content of lower than 0.01%,0.75%?0.96% magnetic powder rate and reductive coal is 808.5?859.3 kg per 1 t DRI.更多还原