Foaming and the Rate of the Carbon-Iron Oxide Reaction in Slag

Abstract

Foaming in the electric arc furnace is achieved by injecting carbon into slag, where the resulting reaction of the carbon with FeO dissolved in the slag generates gas (CO) that causes the slag to foam. In this research, the rate of the reaction of FeO in slag with carbon and the resulting foam height were measured. In these experiments, the FeO content of the slag ranged from 15 to 45 mass pct, and several different types of carbon were used including graphite, coals, and chars. The rate of the slag-carbon reaction and the consequent CO generation increased with FeO content of the slag from 15 to 45 mass pct. However, the slag foam height reached a maximum at about 25 mass pct FeO and decreased at higher FeO contents. The decrease in foaming is apparently due to a decrease in the foam index or foamability caused by a decrease in viscosity and an increase in density of the slag with FeO content. The results of this work indicate that the foam height is influenced more significantly by the decrease in the foam index compared to the increase in the CO gas generation rate at higher FeO contents. The decrease in the foam index with FeO agrees with that predicted from the slag properties.

Recycling Waste Polymers in EAF Steelmaking: Influence of Polymer Composition on Carbon/Slag Interactions

“…viscosity, density, surface tension and basicity) depend on slag composition and temperatures; these are known to affect the foamability of the slag. 3,4) A number of studies have been carried out using various techniques to investigate slag foaming as a function of slag characteristics. [5][6][7] A few researchers investigated the influence of the carbonaceous materials on interactions with slag; basic characteristics of carbon sources were found to play a significant role.…”

Interactions between Liquid Slag and Graphite During the Reduction of Metallic Oxides

“…While the probable reduction mechanism in liquid slag phases has been widely accepted by researchers, the specific mechanism controlling the kinetics of the process has still remained unclear [6]. The factors controlling the reduction rate include the following: physical properties of slag phase, phase-to-phase voltage between gas -slag, slag -reducer, slag -metal and slag density.…”

“…The reduction rate is also influenced by such factors as the type of carbon used and the size of its particles (subdivision surface). Other important issues involve: the influence of the dynamic viscosity rate which dynamically changes in the course of the reduction process, the influence of surface tension of liquid slag as well as the interactions between liquid slag phase and the reducers used (most often carbon reducers) [1][2][3][4][5][6][7][8][9].…”

“…Paper [6] describes research into slag foaming which is a result of FeO and carbon reaction in liquid slag. Carbon was introduced in different forms, such as raw carbon, charcoal (pyrolytic, active) and graphite.…”

“…This phenomenon, however, did not increase slag foaming per mass unit of carboniferous materials that were blown in. The influence of different forms and amount of carbon as well as the size of particles should be examined further in order to understand and optimize the foaming process [6]. It was also stated that the mechanism controlling the reduction rate remains to a large extent unclear [6].…”