南非PMC精粉与两种典型褐铁矿的配矿优化

Optimization on ore-blending of PMC concentrate and two typical limonite ores

PMC精粉的铁品位及TiO_(2)质量分数较高,分别为62.5%和2.6%。PMC精粉较巴西卡粉和其他铁精粉资源有明显的价格优势,在铁矿石市场上有较好的流通性,广泛应用于国内多家钢铁企业的烧结生产中。邯钢烧结混匀矿中PMC精粉所占比例为4%~6%,为了更加充分合理地利用PMC精粉,根据邯钢的配矿特点,研究了PMC精粉与褐铁矿的二元、三元配矿优化问题。首先研究了PMC精粉、FMG混合粉、杨迪粉等3种铁矿粉的物理化学性质、烧结基础特性以及经过黏结相强度试验后试样的矿相组织特征;然后基于单品种矿粉的烧结基础特性,以液相流动性和黏结相强度为考察指标,开展了PMC精粉与褐铁矿的配矿优化试验。试验结果表明,PMC精粉具有TFe、CaO、MgO含量高以及SiO_(2)、Al_(2)O_(3)含量低等优点,但PMC精粉也存在高TiO_(2)、高磷且同化温度高、液相流动性差等问题,PMC精粉与褐铁矿在化学成分、粒度组成以及烧结基础特性等方面均有很好的互补性。二元混匀矿的液相流动性随PMC精粉配比的提升而减弱;二元混匀矿的黏结相强度随PMC精粉配比的提高基本呈现为先升高后降低的趋势,当PMC精粉与杨迪粉质量比为1∶3,PMC精粉与FMG混合粉质量比为1∶2时有最高的黏结相强度,分别为1785 N和1605 N。基于二元最优配比的三元混匀矿也具有较高的黏结相强度(1270 N),混匀矿中褐铁矿与PMC精粉质量比由2.5∶1提升至4∶1中增配杨迪粉较FMG混合粉对混匀矿黏结相强度的降低影响较小,分别降低为1170 N和740 N。矿相结果表明,混匀矿的流动性指数为3.0~3.5时,矿物组织中大气孔含量以及气孔尺寸均会明显减小,从而有效改善了试样的黏结相强度。

The mass percent of TFe and TiO_(2) for PMC concentrate(PMC for short)is relatively high,with a value of 62.5% and 2.6% respectively.Compared to iron ore fines of Carajas(IOC)from Brazil and other imported iron ore concentrates,PMC has an advantage in price and hence a strong liquidity in iron ore market.As a result,it is widely used in iron ore sintering process by many domestic steelworks.The proportion of PMC in iron ore mixtures for sintering in Hansteel is about 4%to 6%.To make full use of PMC in sintering,based on the ore-blending practice in Hansteel,the optimization on binary and ternary systems of PMC and two limonite ores(Yandi fine and FMG blend)was studied thoroughly.Firstly,the physicochemical properties,sintering basic characteristics and mineralogical composition after the test of bonding-phase strength for the aforementioned ores were examined.Considering the sintering basic characteristics of the tested iron ores,taking liquid-phase fluidity and bonding-phase strength as the sintering performance indexes,the ore-blending optimization between PMC and the two limonite ores was carried out.The experimental results show that the high contents of TFe,CaO and MgO and low contents of SiO_(2) and Al_(2)O_(3) are the advantages of PMC,while the main problems of PMC for sintering are high contents of TiO_(2) and P,high digestion temperature and poor fluidity of liquid phase.Property complementarity in chemical composition,particle sizes and the sintering basic characteristics between PMC and the two limonite ores can be found and applied to ore-blending of the sinter mixtures.Increasing PMC content in the binary ore blending would weaken its liquid-phase fluidity gradually.However,the bonding-phase strength will basically be enhanced firstly and then drop sharply with the increase of PMC content from 0 to 100%.When the mass ratio of PMC to Yandi fine or to FMG blend is 1∶3 or 1∶2,the maximum bonding-phase strength of the mixtures can be obtained,with a value of 1785 N or 1605 N separately.The bonding-phase strength of the ternary mixture derived from the optimized binary blending was also high,that is 1270 N.With the mass ratio of limonite ores to PMC increasing from 2.5∶1 to 4∶1,FMG blend has a stronger influence than Yandi fine on bonding-phase strength,with its value dropped to 740 N,while that is 1170 N for the Yandi fine.Mineral phase analysis on samples after bonding-phase strength test indicated that:with the liquid-phase fluidity of the mixture falling in the range of 3.0 to 3.5,both the quantity of macro pore and the mean pore diameter in mineral phases can be decreased significantly,and thus the bonding-phase strength of the sample can be improved effectively.