低品位铁矿球团微波加热煤基直接还原-磁选试验研究

针对某铁品位48.92%的赤褐铁矿采用内配煤粉的方式造球, 再进行微波加热直接还原-磁选分离。研究结果表明, 微波对整个内配碳球团同时加热, 且优先加热其中的煤颗粒和铁矿物, 有助于赤褐铁矿快速分解和还原成金属铁, 此时脉石矿物温度较低, 不仅抑制了铁橄榄石等化合物的生成, 而且在热应力的作用下有利于金属化球团的磨选分离。在物料量270 g, 微波输出功率1.4 kW, 内配碳球团经62 min焙烧后温度可达1 200 ℃, 此时球团金属化率高达96.23%; 当磨矿时间20 min, 磁场强度120 kA/m时, 可获得铁品位75.83%、铁回收率91.45%的铁精矿。

Experimental Study on Coal-based Direct Reduction-Magnetic Separation for Low-grade Iron Ore Pellets by Microwave Heating

Hematite-limonite ore with 48.92% Fe was firstly pelletized by coal blending, then subjected to the process of  direct reduction-magnetic separation by microwave heating. The results showed that the whole carbon-containing pellets can be heated by the microwave at the same time, but the coal and iron oxide particles would take priority over others in the heating process, resulting in the separation between hematite and limonite and reduction to metallic iron quickly. Meanwhile, the lower temperature of gangue mineral therein can not only inhibit the formation of compounds such as fayalite, but also promote the grinding and separation of the metallic pellets under the thermal stress. With the material at the amount of 270 g and output power of microwave at 1.4 kW, the temperature of carbon-containing pellets can reach as high as 1 200 ℃ after 62 min roasting. At this moment the metallization rate of the pellets reaches up to 96.23%. With the milling time of 20 min and magnetic field intensity of 120 kA/m, the iron concentrate with 75.83% grade and 91.45% recovery can be obtained.