钢渣中RO相微波加热的晶体生长特征

Crystal growth characteristics of RO phase microwave heating in steel slag

以钢渣为研究对象,通过热重-差示扫描量热(TG-DSC)和光学显微分析等研究方法,探究了在微波加热过程中熔融温度、保温时间、降温速率和结晶温度对钢渣中RO相晶体生长的影响,获得了钢渣中RO相微波加热的晶体生长特征。研究结果表明:钢渣熔融温度为1400℃;降温过程中,RO相的平均粒径随着降温速率的减小而增大,但降温速率过低会导致晶体粒径尺寸分布不均匀。降温速率为1℃/min时,RO相晶体的粒径分布均匀且晶界清晰,结晶温度降低,RO相晶体平均粒径先增加后减小;结晶温度为1180℃时,RO相晶体的平均粒径达到最大值,RO相晶体粒径从26μm长大到43μm,是原晶体平均粒径的近2倍,实现了钢渣中RO相晶体粒径的长大,且晶体形貌完整、晶界分明。微波处理后钢渣分选精矿中全铁(TFe)含量提高至原钢渣分选后精矿的1.2倍。

The effects of the melting and crystallization temperatures,holding time,and cooling rate on the growth of RO phase(an MgO-FeO-MnO solid solution)crystals in steel slag during microwave heating were investigated using thermogravimetric differential scanning calorimetry and optical microanalysis;hence,the crystal growth characteristics were derived.The results reveal that steel slag has a melting temperature of 1400℃.The average particle size of the RO phase crystals increases with a decreasing cooling rate;however,an excessively low cooling rate yields an uneven crystal particle size distribution.For a cooling rate of 1℃/min,the RO phase-crystal particle size distribution is uniform and the grain boundaries are clear.As the crystallization temperature decreases,the average RO phase-crystal particle size increases.When the crystallization temperature is 1180℃,the average RO phase-crystal particle size is maximized,almost doubling from 26μm for the original crystal to 43μm.Therefore,particle growth is achieved for RO phase crystals in steel slag.A complete crystal morphology and clear grain boundaries are obtained.Finally,the total iron content of the separated post-treatment steel slag is 1.2 times that of the pre-treatment concentrate.