磁化焙烧过程中磁性转化率对磁选影响规律研究

磁化焙烧—磁选是目前处理难选铁矿的主要方法之一，为了探究焙烧工艺参数对赤铁矿磁性转化率及磁选指标的影响规律，以天然赤铁矿纯矿物为研究对象系统地开展了赤铁矿磁化焙烧—磁选试验，并采用偏光显微镜及XRD探究了磁铁矿的生长趋势和物相转变过程。结果表明：针对本研究试样，适宜的焙烧条件为焙烧温度550 ℃、CO浓度20%、还原时间4 min，此时赤铁矿的磁性转化率为32.99%，样品的磁选回收率达到99.58%。赤铁矿焙烧过程中新生磁铁矿首先在矿物表面及裂隙生成，随着焙烧时间的增加，新生磁铁矿沿矿石颗粒表面向内部生长。当颗粒外层部分被还原为磁铁矿，赤铁矿转化率达到32.99%时，整个颗粒即可在磁选过程中被回收，无须将赤铁矿完全还原为磁铁矿，便可获得良好的磁选指标。

Study on the Effect Law of Hematite Conversion Rate on Magnetic Separation during Magnetization Roasting

Magnetization roasting and magnetic separation is one of the main methods for treating refractory iron ores at present.In order to explore the influence law of roasting process parameters on hematite magnetic conversion rate and magnetic separation index,magnetization roasting-magnetic separation test of hematite with natural pure hematite as the research object were systematically carried out,and the growth trend and phase transformation process of magnetite were explored by polarizing microscope and XRD.The test results showed that:aiming at the sample,the suitable roasting temperature of hematite is 550 ℃,the CO concentration is 20%,and the reduction time is 4 min.At this time,the magnetic separation recovery of the sample reaches 99.58%,and the magnetic conversion of hematite is 32.99%.In the roasting process of hematite,newborn magnetite is first formed on the mineral surface and cracks.With the increase of roasting time,newborn magnetite grows internally along the surface of ore particles.When the outer part of the particles is reduced to magnetite and the conversion rate of hematite reaches 32.99%,the whole particles can be recovered in the magnetic separation process,good magnetic separation indexes can be obtained without completely reducing hematite to magnetite.