Insearch Of Sintering Behavior Of Limonite

There is an increasing amount of imported iron ore used as raw material in sintering recently, in which the proportion of low cost limonite is more and more high with the reduction of high-quality iron ore resources. Therefore, it is of great significance to study the behavior and mechanism of limonite in sintering to establish a theoretical basis for the sintering technology with limonite of high ratio, which is beneficial for ore purchasing, ore proportioning and producing in iron and steel enterprises.Some properties of limonite were investigated to reveal its sintering behaviors, including dehydration, roasting characteristics and metallogenic performance in sintering process. The influence of limonite’ proportion on sinter quality and quantite for magnetite/limonite and hematite/limonite sintering systems were studied by sinter pot test. The influence mechanism of limonite on the sinter’s strength in different sintering systems were studied by liquid formation properties of ore-blending, mineral composition and microstructure of sinter and sintering behavior of limonite.The tests of sintering behavior of limonite showed that, limonite with higher crystal water had lower temperature forming crack, more cracks and greater dehydration rate. The burst performance of limonite particles was not only relevant to the dehydration rate, but also the porosity. The metallogenic performance of limonite was better than hematite and magnetite for the faster speed and the larger amount of liquid forming.The sintering tests showed that, the sintering speed rose with the increase of limonite in magnetite/limonite sintering system, in which the drum strength and utilization factor changed as a parabola, thus the optimal proportion of limonite in this system were40%-60%. However, the drum strength and utilization factor decreased with the increase of limonite in hematite/limonite sintering system in spite of the sintering speed accelerated, and the proportion of limonite in this system should not beyond40%. The mechanisms showed that, for magnetite/limonite sintering system, magnetite which had a small size and bad metallogenic performance wrapped limonite as adhesive layer, formed a cover which reduced the permeation and assimilation of liquid phases into limonite particles, what’s more, the calcium ferrite shape was mainly needle of good strength. For hematite/limonite sintering system, there was too fast rate and large amount of liquid phase forming because of few adhesive powder and high relative basicity, which reduced the quality of binder phase, and calcium ferrite shape became plank or bulk of poor strength, aggravated the permeation of limonite particles, thus the strength of sinter deteriorated.