Improving Sintering Performance Of Fine Iron Ore Concentrate By Pre-granulation Technology

With the rapid development of China’s steel industry, the import of iron ore is increasing, also iron and steel enterprises strive to use their own iron ore concentrate in order to reduce the cost. While there are lots of problems in sintering using iron ore concentrate, therefore, it’s necessary to study the properties of iron ore concentrate, find out the efficient way of using iron ore concentrate on sinter performance, and obtain strengthening methods of iron ore concentrate sintering on that basis.Study on iron ore concentrate suitable parameters and sintering properties showed that, with the increase of iron ore concentrate, the suitable granulation moistures increased, the tumble index and the yield of sinter were strengthened when iron ore concentrate increased from0%to35%, while the tumble index and the yield of sinter were reduced when iron ore concentrate was greater than50%.The sinter index was markedly deteriorated when the concentrate proportion increased to70%.The result of granulation showed that, when the proportion was more than70%, the granulating balls grew up together, formed to be a large ball, also the rate of drying powder was increased. The result of mineralization showed that, with the increase in the proportion of iron ore concentrate, the liquid phase forming temperature and completed temperature were raised, the liquid phase formations of mixture become harder. The result of mineral composition and microstructure showed that, when the proportion was more than50%, the content of calcium ferrite was decreased, while the content of magnetite was increased, the content of acicular and columnar of calcium ferrite was decreased, pores in the sinter relatively increased.Taken together with our previous study, when28%hematite concentrate in sinter mix,9.3%of lime,1.5%of coke could get the excellent sintering indexes. The result showed that the tumble index and the yield of sinter increased from67.47to70.75%, from77.18to80.23%, respectively. Under the pre-granulation, the rate of drying powder was decreased by2.47%. The result of remained sinter samples showed that pre-granulating of iron ore concentrate could decrease the liquid phase forming temperature and completed temperature. The sinter melting area obtained the melting corrosion structure that was formed by magnetite and calcium ferrite, while pre-granulation for iron ore concentrate could increase the contents of calcium ferrite and hematite, decrease the content of magnetite, and produce markedly acicular and columnar of calcium ferrite that lead to improve the sinter strength. There are27figures,38tables and77references in this paper.