新疆某镜铁矿石磁化焙烧过程研究

摘要

There are 35.20％ iron and 30.64％ calcium oxide in specularite ore from Xinjiang.Iron mineral is mainly specularite,while gangue minerals are mainly calcite and quartz.The specularite is micro-fine disseminated in ore,and is a typical refractory iron ore.In order to study phase transformation of iron minerals during magnetic roasting process,effects of roasting temperature,roasting time and coal ratio on magnetic roasting results and phase transformation of iron minerals of specularite ore were investigated.The results indicated that iron concentrate with iron grade of 65.95％,recovery rate of 77.70％ can be obtained under the conditions of coal powder with mass ratio of 12％,reduction temperature of 800 ℃ for 75 min,magnetic separation was brought at magnetic field intensity of 120kA/m after ground the roasted products at 90％ passing 0.074 mm.Meanwhile,roasting temperature intense influences magnetic roasting process.When roasting temperature blew 800 ℃ Fe2O3,specularite can transform to Fe3O4 through magnetic roasting.The content of Fe3O4 is highest at roasting temperature of 800 ℃;when the roasting temperature is higher than 800 ℃,portion of Fe3O4 translated to FeO,and specularite is over-reduction.The content of FeO is highest under roasting temperature of 900 ℃;When roasting temperature rise to 1 000 ℃,portion of FeO will translated to metallic Fe.The process of phase transformation corresponds to results of magnetic separation.2CaO · Fe2O3 is produced at 900 ℃ resulted from portion of Fe2O3 reaction with CaO,which could not recovered by magnetic separation.The results can provide technical reserence for comprehensive utilization of specularite ore.%新疆某镜铁矿矿石TFe含量为35.20％,CaO含量为30.64％;铁矿物主要为镜铁矿,脉石矿物主要为方解石和石英.矿石中镜铁矿嵌布粒度微细,属于难选铁矿石.为考察矿石磁化焙烧过程物相转变规律,进行了焙烧温度、焙烧时间和配煤比对其磁化焙烧效果、铁物相转变过程的影响规律试验.结果表明:在配煤比为12％、焙烧温度为800℃、焙烧时间为75 min条件下还原焙烧后,焙烧产品磨细至-0.074 mm占90％,在磁场强度为120 kA/m条件下弱磁选,可获得铁品位为65.95％、回收率77.70％的指标.焙烧温度对镜铁矿磁化焙烧过程影响显著.焙烧温度低于800℃时镜铁矿磁化焙烧转变为Fe3O4,焙烧温度为800℃时,焙烧产品Fe3O4含量最高;焙烧温度高于800℃时,部分Fe3O4又被还原为FeO,产生过还原现象;焙烧温度为900℃时,焙烧产品FeO含量最高;焙烧温度达到1 000℃时部分FeO被还原成金属Fe.此过程与磁选结果的变化规律相符.另外,焙烧温度达到900℃时,部分Fe2O3与CaO反应,生成了2CaO·Fe2O3,不能通过弱磁选回收.试验结果为该镜铁矿资源的合理利用提供了技术参考.