细粒磁铁精矿球团孔隙结构的优化研究

Optimization of Pore Structure of Fine-grained Magnetite Concentrate Pellets

针对-10μm粒级含量32.63%、比表面积2 980 cm2/g的细粒磁铁精矿,通过有机粘结剂取代部分膨润土优化细粒磁铁精矿球团的孔隙结构,从而改善了生球及成品球质量。相比单独添加1.75%的膨润土球团,配加0.05%的有机粘结剂使膨润土用量降低至0.8%,由于有机粘结剂使小颗粒团聚成较大的颗粒,使得生球的孔隙率从16.68%提高到23.15%,球团爆裂温度从370℃提高到500℃;且预热过程球团的氧化率从67.48%提高到79.08%,球团均匀氧化避免了球团焙烧时形成双层结构;同时焙烧球孔隙率从12.33%提高到16.83%,使得球团还原度从56.8%提高到69.7%。有机粘结剂部分取代膨润土成功解决了细粒磁铁精矿球团孔隙率低导致的爆裂温度低、氧化速度慢、还原性能差等问题。

For preparing pellet with a kind of fine-grained magnetite concentrate with sizing of-10 μm 32. 63%,specific surface area of 2 980 cm2/g,an organic binder was taken to replace some part of bentonite for optimizing the pore structure,resulting in an improved quality for both the green pellet and roasted pellet. Compared with the preparation with only addition of 1. 75% bentonite,an addition of 0. 05% of the organic binder to reduce the amount of bentonite to 0. 8% resulted in the obtained green pellet with the porosity increased from 16. 68% to 23. 15% and the cracking temperature from 370 ℃ up to 500 ℃,because fine particles were agglomerated into larger particles due to the action of organic binder. The oxidative rate of the pellets was also up from 67. 48% to 79. 08% during preheating and the uniform oxidization prevented from the formation of double-layer structure. It is shown that the roasted pellets was obtained with the porosity up from 12. 33% to 16. 83%,thus the reduction degree increased from 56. 8% to 69. 7%. It is concluded that problems of low cracking temperature,slow oxidative rate and low reduction degree resulting from low porosity of pellets can be solved by replacing part of bentonite with organic binder.