基于相图分析铁酸钙流动性及烧结矿强度

铁酸钙黏结相的流动性是维持烧结矿强度的重要因素。由于铁酸钙黏结相没有固定组成,首先根据相图获得不同成分铁酸钙黏结相的熔点和液相量,在不同SiO_2质量分数条件下,通过试验分析了流动性与熔点和液相量的关系。结果表明,不同SiO_2质量分数的矿石获得最佳流动性的铁酸钙成分和碱度不同;铁酸钙流动性与其熔点呈反比,与其液相量呈正比。在此基础上,通过烧结杯试验考察了不同SiO_2质量分数矿石黏结相流动性对烧结强度的影响规律和作用机理。烧结杯试验结果表明,w(SiO_2)等于4.30%的铁矿石在碱度为1.8～2.2时,烧结矿强度都比较高;而w(SiO_2)等于12.42%的铁矿石在碱度为2.0时处于最高值,过高或过低都会使烧结矿强度明显下降。其根本原因是由热力学性质决定的,低SiO_2矿石的液相区间较宽,高SiO_2矿石的液相区间较窄,烧结生产中不建议使用高硅矿石。研究结果可为评价黏结相流动性和新矿种的应用提供理论指导。

Investigation on fluidity of SFCA and sintering strength based on phase diagram

The fluidity of the bonding phase SFCA （sillico-ferrite of calcium and aluminum） is important for the sintering strength. The fluidity of SFCA with different w（SiO2） was investigated based on the phase diagram analysis in the present work considering that the SFCA has not a certain chemical composition. The experimental results show that ，for different iron ore （different SiO2）， the chemical composition （or basicity） aimed for best fluidity is different； the fluidity of the SFCA is proportional to the amount of liquid， and is inversely proportional to the liquidus temperature. Then， the effects and mechanism of the fluidity and the w（SiO2） in iron ore on the sintering strength were investigated by sinter pot tests. The sintering experiments show that， in case of iron ore with w（SiO2）＝4.30%， the sintering strength is higher in the range of 1.8-2.2 of basicity， while in case of iron ore with w（SiO2）＝12.42%， the sintering strength obviously decreases when the basicity is higher or lower than 2.0 （peak value of basicity）. The fundamental mechanism is due to thermodynamics. The liquid zone is wider for low-SiO2 iron ores （w（SiO2）＝4.30%）. However， the liquid zone is narrower for high-SiO2 iron ores （w（SiO2）＝12.42%）. Therefore， the iron ore with higher w（SiO2） is not proposed being used in the sintering production. The research content and results are important for the application of iron ores and their matching.