Microwave-assisted reduction roasting of a goethite-rich, reject iron ore waste stream (−2 mm) was used to produce a high-grade concentrate. Reduction roast experiments were conducted at 370 °C, 450 °C, 600 °C and 1000 °C under gas atmospheres of 30:70 and 40:60 CO/CO₂, with a soak time of 20 min. Goethite was converted to hematite above 370 °C under both gas mixtures while at the higher roasting temperatures, increasing amounts of magnetite formed. Roasting conditions for the best conversion of goethite to synthetic magnetite were 600 °C in a gas atmosphere of 40:60 CO/CO₂, with a soak time of 20 min. Laboratory-based magnetic separations in a Davis tube indicated that a blast furnace grade (+62 wt% Fe) pellet concentrate could be produced with an acceptable iron recovery of > 88 wt%. Under both gas atmospheres, a higher reduction temperature of 1000 °C achieved a greater conversion of goethite to magnetite but resulted in over-reduction and the generation of wüstite, fayalite and Fe-rich spinel phases with different magnetic susceptibilities that are expected to make subsequent beneficiation difficult. Further processing to optimize the microwave-assisted magnetizing roast and the magnetic separation conditions can be expected to maximize the efficiency of upgrading the iron content in low grade goethite-rich iron ores.

富含针铁矿废铁矿废料流（-2毫米）的微波辅助还原焙烧用于生产高品位精矿。还原烘烤实验是在370°C，450°C，600°C和1000°C的30:70和40:60 CO / CO _2的气体气氛下进行的，浸泡时间为20分钟。在两种气体混合物下，针铁矿在高于370°C的温度下都转化为赤铁矿，而在较高的焙烧温度下，形成的磁铁矿量增加。在40:60 CO / CO ₂的气体气氛中，针铁矿向合成磁铁矿最佳转化的焙烧条件为600°C，浸泡时间为20分钟。戴维斯管中基于实验室的磁选表明，可以生产高炉级（+62 wt％Fe）球团精矿，可接受的铁回收率> 88 wt％。在两种气体气氛下，较高的还原温度（1000°C）都可以使针铁矿向磁铁矿的转化率更高，但会导致过度还原，并生成具有不同磁化率的辉铁矿，铁橄榄石和富铁尖晶石相，预计会导致随后的转变。选矿困难。可以预期进一步进行处理以优化微波辅助的磁化焙烧和磁分离条件，以使提升低品位针铁矿富铁矿石中铁含量的效率最大化。