Mineralization Characteristics of Iron Ore Sinter and the Effects of Cooling Rate on Mineral Phase Structure

Abstract

The mineral phase composition and structure of sintered ore are closely related to its quality. Analyzing the characteristics of the phase structure of sintered ores and studying the influence of sintering conditions are important to optimize their quality. In this study, the mineralization characteristics of ore during the sintering process were studied through interrupted quenching experiments. The results clarified the evolution of the structure of the sintered ore phases during the heating and cooling and its mechanism. In this study, the effects of the cooling rate on the mineral composition and structure of sintered ore were also studied. The results showed that the structure of the mineral phase changed during the iron ore sintering process as follows: granular → molten → dissolution texture. During the cooling process, as the temperature decreased, the magnetite and liquid phase contents gradually decreased, and the silico-ferrite of calcium and aluminum (SFCA) and hematite contents increased; however, the porosity did not change to a great extent. The formation of SFCA during the cooling stage consumed hematite and magnetite, and SFCA preferentially formed and grew on magnetite. As the cooling rate of the sinter was increased, the magnetite and silicate contents increased, and the hematite and SFCA contents decreased. Meanwhile, the structure of SFCA changed from block-like to columnar and acicular, and the aspect ratio increased.

Exploring the Relationship Between Fe-rich SFCA and SFCA-III and Their Presence in Sinter Strand and Pot-grate Sinter

“…Other work has described the morphology of magnetite crystals changing from idiomorphic when part of a phase assemblage consisting of magnetite + liquid only at 623 K, to irregular shapes after cooling to room temperature, indicating that the formation of SFCA phases consumed magnetite during the cooling process and with the crystal structures of the SFCA phases containing spinel structural modules. 28) Nicol et al also reported the formation of phase(s) with SFCA-I structure forming during cooling of an Al 2 O 3 composition (i.e., in the SFC system) from a liquid phase at 1623 K. 29,30) The evidence, therefore, that the formation of SFCA-I after melt formation and during cooling does occur is becoming overwhelming, and logically this appears consistent with SFCA-I being intermediate between SFCA-III and SFCA in terms of ordering of the spinel (S) and pyroxene (P) structural modules.…”