微细粒难选铁矿流态化直接还原-磁选研究
文献类型：学位论文
| 作者 | 张朝英 |
| 学位类别 | 硕士 |
| 答辩日期 | 2009-05-30 |
| 授予单位 | 中国科学院过程工程研究所 |
| 授予地点 | 过程工程研究所 |
| 导师 | 朱庆山 |
| 关键词 | 细嵌布粒度赤铁矿 流化床 磁化焙烧 直接还原 磁选 |
| 其他题名 | Study on Direct Reduction in Fluidized Bed and Magnetic Separation of Fine Distributed Hematite |
| 学位专业 | 化学工程 |
| 中文摘要 | 随着我国钢铁工业规模的不断扩大，我国己成为世界上最大的铁矿石进口国，进口铁矿石的数量己占我国铁矿石需求总量的一半以上。2005年之后，进口铁矿石的价格大幅度提高，对我国钢铁工业的发展产生巨大的压力，开发利用我国自有的铁矿石迫在眉睫。而我国自有铁矿石品位低，嵌布粒度细，目前的选矿技术很难对这部分铁矿石进行利用。 磁化焙烧是处理难选赤铁矿比较有效的方法之一，但是，对于细嵌布粒度的铁矿石，磁化焙烧－磁选已不能将其分离。因为只有当矿石颗粒被磨到很细时才能达到单体解离，但此时铁矿颗粒和脉石的比磁化系数差很小，在磁场中，铁矿颗粒所受的磁场力小于机械力，所以铁矿颗粒随水流排入尾矿，降低了选矿指标。 直接还原是将铁矿石直接还原为金属铁。金属铁与脉石的延展性差异大，对还原矿进行磨矿，金属铁被磨为具有较大比磁化系数的铁片，脉石被磨为粒径很小的颗粒而脱离铁片，两者的比磁化系数差异显著。磁选时，金属铁片所受的磁场力大于它所受的机械力，被留在磁场中，而脉石不受磁场力作用，随水流排入尾矿。 本文选取云南省召夸镇的铁矿石进行实验，该矿属低品位赤铁矿，且嵌布粒度细、分布不均。实验中采用流化床作为磁化焙烧和直接还原装置，分别以CO-N2和H2-N2作为还原气，考察磁化焙烧－磁选和直接还原－磁选的影响因素。结果表明：直接还原－磁选所得精矿指标要明显优于磁化焙烧－磁选所得指标，精矿品位由51.69%提高到了73.79%，而回收率基本不变。以H2-N2做还原气时还原矿金属化率为86.52%，比由CO-N2作还原气时的64.08%提高了20%。将所选矿石在H2-N2气氛中的流化床中进行直接还原所得还原矿进行二次磨矿，然后在磁选管中磁选，矿石品位由26.78%提高到了73.79%，铁回收率也可达到76.10%，比按传统的磁化焙烧－磁选方法所得结果有较大的提高。 从实验中可以得出，流化床中直接还原效率高。磁选前的磨矿不仅增大了单体解离度，也增大了脉石和矿石比磁化系数的差，有利于后续的磁选。直接还原－磁选工艺对于细粒级难选铁矿的选矿有较明显的效果。 |
| 英文摘要 | With the fast economic growth, the iron ore consumption of China has been increased dramatically in the past several years. Currently, the ratio of dependence on foreign iron ore has reached over 50%, which greatly endangers the supply security of iron ore and the healthy development of the iron and steel industry of China. The only way to improve the supply security is to utilize domestic low-grade iron ore resource that cannot be beneficiated effectively by conventional beneficiation processes. Magnetizing roasting, which converts iron oxides to magnetite to increase the specific susceptibility difference of iron oxide and gangues, is the commonly used process for the low-grade iron ore beneficiation. However, the process is not effective during processing iron ore of finely distributed iron oxides, since in order to physically separate iron oxide and gangue these iron ores need to be ground to very small particles (e.g. less than 10 micrometers), which makes it very difficult to separate the fine magnetite with gangue of similar size by the subsequent magnetic separation process, resulting in low iron recovery rate. It is therefore necessary to explore new ways for the beneficiation of the finely distributed iron ore. The present study explores the beneficiation of finely distributed iron ores with the direct reduction-magnetic separation process. The iron ore from Zhaokua town of Yunnan province was employed in the present study. The iron ore has the TFe of 26.7 8%. Microstructure characterizations show that hematite particles of 10-50 micrometers unevenly distributed in the gangue matrix. With the magnetizing roasting-magnetic separation process, the iron content in the ore concentrate can only reach to 51.69% with an iron recovery rate of 72.49%. Consequently, the iron ore was subject to direct reduction under both CO-N2 and H2-N2 atmospheres using a fluidized bed reactor. It was found that the metallization degree can reach to 86.52% after reduced for 60 min at 700℃ under the H2-N2 atmospheres, which is ~20% higher than under the CO-N2 atmosphere. The magnetic separation process has also been optimized in order to obtain high iron content ore concentrate with favorable iron recovery rate. After optimize the whole process, the iron ore concentrate of TFe 73.79% with the recovery rate of 76.10% has been obtained, which is much better as compared with those obtained by the magnetizing roasting-magnetic separation process. It was found that thin iron sheets formed after grinding due to the ductibility of the directly reduced iron. The grinding-induced thin sheets may increases the specific susceptibility difference between the reduced iron and the gangue, which was proposed to be the main reason for the improved beneficiation efficiency. In conclusion, grinding the directly reduced iron can extend magnetic force generated by electricity during the beneficiation process. It has been proved that direct reduction under H2-N2 atmospheres with magnetic separation process is effectively for the finely distributed iron ore. |
| 语种 | 中文 |
| 公开日期 | 2013-09-16 |
| 页码 | 58 |
| 源URL | [http://ir.ipe.ac.cn/handle/122111/1278]  |
| 专题 | 过程工程研究所_研究所（批量导入） |
| 推荐引用方式 GB/T 7714 | 张朝英. 微细粒难选铁矿流态化直接还原-磁选研究[D]. 过程工程研究所. 中国科学院过程工程研究所. 2009. |
入库方式： OAI收割
来源：过程工程研究所
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