Abstract

The current study investigates the beneficiation of iron ore fines by the carbothermal process using muffle and microwave furnace. The muffle furnace reduction was found useful for the separation of iron-bearing phases from the quartz impurities and concentrate with iron purity of ~ 64%, recovery of 98%, and a yield of 84.5% is achieved at 900 °C, 9% charcoal in 1 h. Incorporating coal as a reductant followed a similar trend as charcoal, although the leaner reduction rate leads to limited fayalite formation and, consequently, better magnetic property at a higher temperature. The microwave exposure of ore led to a temperature of ~ 750 °C in 15 min, and the ore-reductant mixture attained 960 °C with charcoal and ~ 800 °C with coal. The microwave reduction yielded comparable concentrate iron grade-recovery with muffle furnace reduction at comparatively lower carbon dosage (6%), suggesting better carbon utilization. Meanwhile, coal-based microwave reduction followed the opposite trend as muffle furnace reduction, and iron grade decreases with an increase in carbon dosage. The optimal conditions of 6% charcoal and 800 W yielded concentrate of 63.8% Fe, 99% recovery with 87.4% product yield. The maximum separation efficiency of the muffle furnace reduction is 80% at 1000 °C with 18% charcoal compared to 70% in the microwave at 6% charcoal, indicating the latter route is efficient and economical. The separation efficiency remains unaltered with carbon dosage suggesting minimal carbon required for achieving maximum separation is 6% C. The metallization of the product of microwave reduction was the functionality of reductant dosage and increases exponentially with carbon dosage. The ferrite formation is initiated at 12% C with maximum metallization of 38.5% at 27% charcoal and 900 W power. The maximum metallization in muffle furnace reduction is 16% at 1000 °C and 18% C. The techno-economic comparison indicates incorporating microwave reduction reduces processing time by 25%, and the carbon consumption is reduced by 35.5%.

Graphical Abstract

中文翻译：

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碳热微波处理富集铁矿粉

摘要

目前的研究研究了使用马弗炉和微波炉通过碳热工艺对铁矿粉的选矿。发现马弗炉还原法可用于从石英杂质和精矿中分离出含铁相，铁的纯度约为64％，回收率达98％，在900°C和9％的木炭条件下产率为84.5％。在1小时内 掺入煤炭作为还原剂的趋势与木炭相似，尽管稀薄的还原速率导致铁铝沸石的形成受限，因此在高温下具有更好的磁性能。矿石的微波暴露导致15分钟内温度达到750°C，还原剂混合物中的木炭达到960°C，煤达到800°C。微波还原可在较低的碳用量（6％）下与马弗炉还原产生类似的精铁品位回收，表明碳利用率更高。同时，煤基微波还原的趋势与马弗炉还原的趋势相反，铁含量随着碳用量的增加而降低。6％的木炭和800 W的最佳条件可产生63.8％的铁精矿，回收率达99％，产品收率达87.4％。马弗炉还原的最大分离效率在使用18％的木炭的情况下在1000°C下为80％，而在微波下使用6％的木炭的分离效率为70％，这表明后一种方法是有效且经济的。分离效率与碳剂量保持不变，表明实现最大分离所需的最小碳为6％C。微波还原产物的金属化是还原剂剂量的功能，并且随着碳剂量的增加呈指数增长。在27％的木炭和900 W的功率下，在12％C时开始形成铁素体，最大金属化率为38.5％。在1000°C和18％C的温度下，马弗炉还原的最大金属化率为16％。技术经济比较表明，采用微波还原技术可使处理时间减少25％，碳消耗量减少35.5％。

图形概要