On Degradation of Self-Fluxing Sinters in the Top of the Blast Furnace

Abstract

Many experiments of bench scale previously reported that hematite in sinter plays a vital role for the degradation of sinter during reduction at low temperatures.
In order to elucidate this phenomenon in actual blast furnace, flue dust from blast furnace and sinter charged were compared, using the samples taken from Nagoya No 1 blast furnace which is operated with high sinter ratio of 85% in burden. The coke in the flue dust is removed with heavy media separation before undergoing to tests.
The results of chemical analyses and mineral composition determination with X-Ray diffraction method showed that the hematite tends to concentrate into flue dust.
The flue dust particles are classified into 6 categories according to the crystal structure of hematite, with the point counting method under microscope. The results showed that the flue dust contains a lot of paticles bearing the hematite, i. e., particles bearing rhombohedral crystals of the hematite, and the magnetite crystals with the hematite lamellae.
From the above test results, it is considered that the degradation of self-fluxing sinter in the blast furnace would be influenced by the hematite, especially rhombohedral and lamellae hematites, in sinter.