含铌铁精矿含碳球团还原过程中微观结构变化研究

Microstructure change of niobium-bearing iron concentrate carbon-containing pellets during reduction

借助SEM、EDS、XRD、化学分析等手段,对不同还原焙烧条件下含铌铁精矿含碳球团的金属化率、形貌、物相组成及元素分布等进行表征,在实验室模拟转底炉条件下研究了直接还原过程中铁矿物和钛、铌矿物的微观结构变化。结果表明,适当地提高还原温度或延长还原时间,有助于提高球团的金属化率,本实验条件下,在还原温度1100℃时保温20min,球团金属化率达到最大,约为86%;此外,随着还原温度的升高或还原时间的延长,金属铁不断聚集、长大,形成较大的金属颗粒,并逐渐连结形成网状结构,渣铁明显分离,含铌、钛矿物也聚集在一起分布在渣相中,为后续铌和钛的富集提供了有利条件。

The metallization rate,morphology,phase composition and element distribution of niobiumbearing iron concentrate carbon-containing pellets under different reduction calcination conditions were characterized by SEM,EDS,XRD and chemical analysis.Under the simulated condition of rotary hearth furnace,the microstructure changes of iron minerals and niobium and titanium minerals during direct reduction process were studied.The results show that,the increase of reduction temperature and the prolonging of reduction time are beneficial to improving the metallization rate of pellets.In this study,the metallization rate of pellets can reach the maximum value of around 86% after reduction at 1100 ℃ for 20 min.In addition,with the increase of reduction temperature and reduction time,the metallic iron particles start to aggregate and grow up into large iron nuggets,and a network structure of metallic iron will be formed gradually;meanwhile,the slag and iron phase also separate gradually,niobium and titanium containing minerals will gather together in the slag phase,which can provide favorable conditions for the follow-up niobium and titanium enrichment.