In Situ Observation of High Temperature Properties of Iron Ore and Its Application in Optimizing Sintering Ore Matching of SHOUGANG JINGTANG

摘要

In recent years,with the constant increase of iron ore price and deficiency of high quality iron ore resources,profitability of steel enterprises has been continuously decreasing.Improvement in efficient use of iron ore in sintering and ironmaking process becomes more and more important.Therefore,much attention has been paid to optimizing sintering ore matching.Conducting studies on high temperature properties of iron ore (such as assimilation,fluidity and fusibility) to optimize sintering ore composition by matching the high temperature properties of various ores has become one of the important methods to improve efficient use of iron ore.Factsage software was used to calculate liquid phase formation of mixtures of iron ore and CaO,and then in situ observation of melting and solidifying process of mixtures of iron ore and CaO was carried out with Confocal Scanning Laser Microscopy (CSLM).The formation,development and solidification of liquid during sintering process have been analyzed and discussed.Results showed that before liquid formation during the sintering process,shrinkage of samples can be explained by the polymerization phenomenon caused by solid phase sintering and exclusion of pores in iron ores.For the different ore mixtures with the same amount of CaO added (Ca:Fe=1:1),CAJ fines displayed high fluidity properties.However,at constant basicity (R=4),the fluidity of CAJ fines was very low due to its low SiO2 concentration.It was found that experimental results varied significantly with the experimental methods used.Comparing with Brazilian sintering fines,the melts forming temperature of CAJ fines was higher,while the fluidity of CAJ fines was higher too,indicating that adhering properties of sinter ore can be improved by replacing Brazilian sintering fines with CAJ fines.The above in situ observation results were applied in the optimization of ore matching in SHOUGANG JINGTANG sinter plant.In earlier 2011,Brazilian sintering fines were substituted by CAJ fines (13％→18％) to improve the fluidity of mixed ores.In later 2011,Brazilian sintering fines,PB fines and domestic fines were substituted by the combination of CAJ fines (18％→25％) and HAI NAN fines (0％→2％)and resulted in further improved sinter properties and also reduced cost of ore matching.In situ observation and industrial application results showed that there was optimum amount of liquid required during the sintering process.Mixed ores composed of collocation of dense ore and fusible ore are better than those composed of relative fusible ore in improving fluidity of melts during sintering process while the same amount of liquid is maintained.