Effect of Slag Melting Behavior on Metal-Slag Separation Temperature in Powdery Iron, Slag and Carbon Mixture

Abstract

Utilization of self reducing pellet in blast furnace is one of the effective technologies to mitigate the CO2 emissions in the steel industry. However, there are not sufficient researches on how the pellet behaves around cohesive zone. Therefore, purpose of this study is to clarify the effect of slag melting behavior on metal-slag separation behavior. In order to simulate the behavior around cohesive zone, electrolytic iron powder, carbon powder, and synthetic slag were prepared as reduced iron, residual carbon and slag components, respectively. They were well mixed as given mass ratios decided from the composition of the self reducing pellet. Different kinds of slag compositions were adopted to change properties, such as melting temperature and viscosity. The mixtures were pressed into tablets and used as experimental samples. "In-situ" observations of metal-slag separation behavior in the mixtures during constant rate heating were done by a laser microscope combined with infra-red furnace and metal-slag separation temperatures were decided. Following results were obtained. The metal-slag separation behavior was dominated largely by agglomeration behavior of liquid phase of iron. The separation surely occurred when both phases of iron and slag change to liquid phases. At the same time, the separation could also occur even if a small amount of solid phases still remained in the mixture. In this experimental condition, the effect of slag melting temperature on the separation was larger than the effect of slag's viscosity.KEY WORDS: slag melting temperature; viscosity of slag; metal-slag separation behavior; agglomeration behavior of Fe-C liquid; laser microscope; "in-situ" observation.

Effects of Charcoal Carbon Crystallinity and Ash Content on Carbon Dissolution in Molten Iron and Carburization Reaction in Iron-Charcoal Composite

“…[10][11][12][13][14][15]17) Charcoal is basically known as carbonaceous material with low ash content. In this study, several kinds of charcoal with relatively low ash content were applied as experimental samples.…”

Effects of Ash Amount and Molten Ash’s Behavior on Initial Fe–C Liquid Formation Temperature due to Iron Carburization Reaction

“…Various investigations [8][9][10][11][12][13][14][15][16][17][18] about iron carburization reaction in ironmaking process have been reported. It has been generally considered that sources of carburization reaction are coke which has direct contact with metallic iron and carbonaceous gas surrounding there.…”

“…There were many reports, which focused on effect of the ash on this reaction. [11][12][13][14][15][16][17][18] However, their discussions were based on comparison among different kinds of carbon sources; coke, coal, graphite, etc. In other words, they could not exclude effects from other factors, especially carbon crystallinity.…”

Metal-slag Separation Behaviors of Pellets Consisted of Iron, Graphite and CaO–Al2O3 Based Slag Powders

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