Identification of Rate, Extent, and Mechanisms of Hot Metal Resulfurization with CaO-SiO2-Na2O Slag Systems

Abstract

The resulfurization of hot metal has not been comprehensively studied in literature. This study presents an experimental and mathematical modeling study of resulfurization in thermodynamic and kinetic point of view. The rate, extent, and mechanisms of resulfurization were evaluated by analyzing concurrently the physical properties and sulfur-extracting ability of the slag. Experiments were conducted in a chamber furnace in an argon atmosphere, and the hot metal was sampled with pre-defined basis. The experiments were continued until the metal-slag system reached an apparent thermodynamic equilibrium. To obtain a quantitative measure on the effect of system properties on the rate and extent of resulfurization, the results of this study were combined with previous studies handling the sulfide capacities of Na 2 O-SiO 2 and CaO-SiO 2-Na 2 O slag systems. The sulfide capacities of the slag and corresponding metal-slag sulfur partition ratios were mathematically modeled with data-driven techniques such as multiple linear and non-linear regression and artificial neural networks. Finally, with the help of these, to study the kinetics of resulfurization, a simple mechanistic reaction model was derived. The results suggest that resulfurization of hot metal follows 1st-order kinetics and that the rate and extent can be regulated through the control of the associated thermodynamic driving force and by modifying the physical properties of the slag. The rate-limiting factor was found to be determined by the morphology of the slag phase.

A Review of Modeling Hot Metal Desulfurization

“…In addition, in the study of Deo et al, it was observed that by optimizing the learning rate of the backpropagation algorithm, the training result for a sparse data set can be improved. Coupling mechanistic and data‐driven modeling was suggested by Vuolio et al, who studied the possible resulfurization of hot metal via an inverse permanent contact reaction at laboratory‐scale by coupling a simple mechanistic model with ANN. In the study, it was observed that the sulfide capacity of the slag contributed the most to the potential for resulfurization.…”

CFD modelling of steel desulfurisation in a gas-stirred ladle

“…The symbol * means the value is at the equilibrium status. The theoretical value of L S can be calculated as follows [14,15,27,28]:…”

“…The symbol means the value is at the equilibrium status. The theoretical value of can be calculated as follows [14,15,27,28]: where is the temperature at the slag-steel interface; stands for the sulfide capacity; and are the oxygen activity and the sulfur activity coefficient in steel, respectively. In this study, the Young’s model [8] is applied to determine the sulfide capacity of slag as shown below:…”