Agglomeration of Return Fines of Sinter for Blast Furnace Raw Materials

Abstract

Return fines of sinter were agglomerated with binder material such as cement and fine powder of blast furnace slag in order to use the agglomerates as raw materials in blast furnace. Reduction tests of the agglomerates were carried out to investigate high temperature properties of the agglomerates. Then, the following findings were obtained. The agglomerates have lower RDI (RDI < 20%) than sinter because brittle sinter were bonded discretely by using soft materials as binder and size degradation during reduction was hindered. The agglomerates have high RI (DI > 70%) than sinter because abundance ratio of fine pore in the agglomerates were high. The agglomerates have equal to or more strength after reduction at 700 and 900 °C because solid phase sintering was promoted by added ultra fine powder of iron oxide. Therefore, the agglomerates of return fines of sinter have more excellent properties in permeability and reducibility than sinter for blast furnace raw materials, and this concept is effective for utilizing sinter fines for blast furnace raw materials in a high pulverized coal ratio and low coke ratio operation.