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Haoyan Sun, Zheng Zou, Meiju Zhang, and Dong Yan , Fluidized magnetization roasting of refractory siderite-containing iron ore via preoxidation–low-temperature reduction, Int. J. Miner. Metall. Mater., 30(2023), No. 6, pp.1057-1066. https://dx.doi.org/10.1007/s12613-022-2576-3
Haoyan Sun, Zheng Zou, Meiju Zhang, and Dong Yan , Fluidized magnetization roasting of refractory siderite-containing iron ore via preoxidation–low-temperature reduction, Int. J. Miner. Metall. Mater., 30(2023), No. 6, pp.1057-1066. https://dx.doi.org/10.1007/s12613-022-2576-3
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难选菱铁矿流态化预氧化-低温还原磁化焙烧

摘要: 磁化焙烧–弱磁选联合工艺是目前实现低品位难选铁矿高效铁资源富集利用的最有效工业化方案之一。菱铁矿(碳酸亚铁)和赤铁矿(三氧化二铁)是两种主要弱磁性难选含铁矿物,菱铁矿在常规工业化赤铁矿还原磁化焙烧条件下会生成弱磁性浮氏体,进而降低磁性物相转化率和最终弱磁选精矿铁元素收得率。对此,本文提出了菱铁矿流态化预氧化–低温还原的磁化焙烧高效物相转化方案,并以低品位陕西菱铁矿为样品进行了系统研究。研究发现,菱铁矿在快速预氧化过程中会生成弱磁性和强磁性三氧化二铁两种铁氧化物,其中强磁性三氧化二铁500–550℃还原焙烧产物除工艺目标物相强磁性四氧化三铁外,还有部分由不稳定四氧化三铁被进一步还原生成的弱磁性浮氏体。预氧化产物只有在更低温度还原焙烧才能实现目标四氧化三铁产物相的稳定存在,优化的菱铁矿流态化快速焙烧完全磁化转变工艺参数为610℃预氧化2.5 min再低温450℃还原焙烧5 min,菱铁矿经此条件磁化焙烧后磨矿弱磁选分离能够达到精矿铁含量62.0wt%、铁元素收得率88.36%的优良指标,相比常规直接还原焙烧铁元素收得率大幅提高34.33%,可以实现低品位难选菱铁矿的高效物相转化资源利用。本文提出的预氧化-低温还原焙烧方案也具有适用于菱铁矿–赤铁矿共伴生铁矿全范围含量比例共磁化焙烧的特点。

 

Fluidized magnetization roasting of refractory siderite-containing iron ore via preoxidation–low-temperature reduction

Abstract: Magnetization roasting is one of the most effective way of utilizing low-grade refractory iron ore. However, the reduction roasting of siderite (FeCO3) generates weakly magnetic wüstite, thus reducing iron recovery via weak magnetic separation. We systematically studied and proposed the fluidized preoxidation–low-temperature reduction magnetization roasting process for siderite. We found that the maghemite generated during the air oxidation roasting of siderite would be further reduced into wüstite at 500 and 550°C due to the unstable intermediate product magnetite (Fe3O4). Stable magnetite can be obtained through maghemite reduction only at low temperature. The optimal fluidized magnetization roasting parameters included preoxidation at 610°C for 2.5 min, followed by reduction at 450°C for 5 min. For roasted ore, weak magnetic separation yielded an iron ore concentrate grade of 62.0wt% and an iron recovery rate of 88.36%. Compared with that of conventional direct reduction magnetization roasting, the iron recovery rate of weak magnetic separation had greatly improved by 34.33%. The proposed fluidized preoxidation–low-temperature reduction magnetization roasting process can realize the efficient magnetization roasting utilization of low-grade refractory siderite-containing iron ore without wüstite generation and is unlimited by the proportion of siderite and hematite in iron ore.

 

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