基于粒度组成调控的高品质球团制备技术

High quality pellet preparation technology based on particle size distribution regulation

中国自产磁铁精矿种类繁多,相较进口精矿有成本优势,但部分精矿因成球性能偏差影响高品质球团制备,开发更为经济有效的调控技术对于这类铁精矿高效利用具有重要现实意义。以A、B、C三种铁精矿作为研究对象,分别具有粒度较粗、颗粒表面光滑和粒度超细的主要特征。查明了影响球团性能的规律:粒度过粗、过细以及颗粒表面光滑的铁精矿均呈现出较差的生球性能,进而导致预热球、焙烧球品质偏差。建立基于粒度组成调控的低品质铁精矿优化配矿方法:依据不同类型铁精矿物理性质、成球性能的差异性和互补性,满足小于0.044mm粒级质量分数60%~70%,优选的配矿方案为A矿∶B矿为1∶4和A矿∶C矿为1∶1,能大幅改善球团性能指标;并揭示了提升球团品质的作用机制,粒度小于0.044mm颗粒对生球爆裂温度有较大影响,且相较于其他粒级,氧化反应速率更快,相同条件下,有利于提高球团强度。

China's domestically produced magnetite concentrates offer cost advantages over imported concentrates,but some of them affect the preparation of high quality pellets due to deviations in pelletizing performance,and the development of more economical and effective control techniques is of great practical importance for the efficient utilization of such iron concentrates.Three typical iron ore concentrates(A,B,and C)with varying particle sizes(coarse,smooth,and ultra-fine)to elucidate the factors affecting pellet performance were examined.It was found that excessively coarse or fine particles and smooth surfaces negatively impact green pellet quality,leading to deviations in preheated and roasted pellet quality.The optimal allocation method of low-quality iron ore concentrate based on particle size composition control was established.Based on the differences and complementarity of physical properties and pelletizing performance of different types of iron ore concentrates,the preferred allocation scheme was 1∶4 for A ore∶B ore and 1∶1 for A ore∶C ore to meet the content of ore concentrates with less than 0.044mm particle size for 60 mass%-70 mass%,which can significantly improve the pellet performance index;and the mechanism of pellet quality improvement was revealed.Ore concentrates with particle sizes less than 0.044mm have a greater influence on the green pellet bursting temperature,and the oxidation reaction rate is faster compared with other particle grades,which is beneficial to improve the pellet strength under the same conditions.