Comprehensive Model of Oxygen Steelmaking Part 1: Model Development and Validation

Abstract

A comprehensive model of oxygen steelmaking that includes the kinetics of scrap melting, flux dissolution, slag chemistry, temperature profile of the system, formation and residence of metal droplets in the emulsion, and kinetics of decarburization reaction in different reaction zones was developed. This paper discussed the development and the application of the model into an industrial practice. The results from the model were consistent with the plant data from the study of Cicutti et al. The model suggested that 45% of the total carbon was removed via emulsified metal droplets and the remaining was removed from the impact zone during the entire blow. It was found that the residence time of droplets as well as decarburization reaction rate via emulsified droplets was a strong function of bloating behavior of the droplets. This model is the first attempt in the open literature that allows for the decarburization kinetics of the impact zone to be predicted separately from decarburization kinetics of the emulsion.

The Influence of Sulfur on Dephosphorization Kinetics Between Bloated Metal Droplets and Slag Containing FeO

“…This work formed the basis of the Bloated Droplet Model, which has since been employed in an overall BOF model by workers at Swinburne University in Australia. [20,21] Notwithstanding very recent work, which suggests bubbles formed on the outer surface of droplets can offer similar increases in residence time, convincing experimental evidence for bloated droplets has been reported by several researchers. [5,6,29] Given the importance of droplet swelling in controlling residence time and the fact that dephosphorization is only favored when slag and metal are in contact, data on dephosphorization of bloated droplets are required for the proper inclusion of dephosphorization in BOF process models.…”

“…Several researchers have studied aspects of droplet behavior relevant to steelmaking including, decarburization, [1][2][3][4][5][6] droplet generation, [7][8][9][10][11][12][13][14][15][16] size distribution, [17,18] and residence time. [19] Other workers have developed models [20][21][22][23] and conducted plant trials, [24][25][26][27][28] which considered the role of droplets in the overall process kinetics. Previous work in the authors' laboratory [6] showed that droplet swelling, caused by CO formation inside the droplet, increased the droplet residence time in the slag, thereby favoring decarburization.…”

Investigation into the Cause of Spontaneous Emulsification of a Free Steel Droplet; Validation of the Chemical Exchange Pathway

“…Reported residence times ranging from 0.4 to 120 seconds are given, with an average of around 40 seconds. [24][25][26][27][28][29][30] The amount of metal in the emulsion has been reported in a complete range of up to 50 pct of the tap weight dependant on blow time. [31,32] With regard to the kinetics of a specific metal droplet in the emulsion, several authors have investigated variable aspects (point 3 & 4 above).…”

Progress in the kinetics of slag-metal-gas reactions, past present and future

“…Kattenbelt and Roffel [52] developed a model to describe the response of oxygen steelmaking to step changes in process variables such as oxygen blow rate, lance height and oxide additions. These workers used insights obtained from work on droplet generation, size distribution and residence time to define the parameters to be considered in an empirical relation for decarburization rate.…”