Abstract:
Knowing the mechanisms that involve the removal of phosphorus from the steel to the slag is very important for the EAF process to be productive and efficient.
There are many studies in the specialized literature on dephosphorization with expressions involving chemical composition and temperature. These expressions, deduced from equilibrium data, generally do not correlate well with industrial data.
The present paper aims to study, using industrial data, the chemical and physical properties of an EAF slag in order to develop new ways to evaluate dephosphorization process and its efficiency regarding these properties.
Different compositions of industrial heat slags, mainly with different CaO and FeO contents were selected to be analyzed. The mentioned slag properties and phases were determined by computational thermodynamics using the software FactSage 8.0 and the results of these analyzes was related to the dephosphorization efficiency.
Based on these simulations, the parameter Dephosphorization Factor [FDeP = aCaO + aFeO + (Nliquid – Nsolid) - 2*Viscosity] was used to measure the slags efficiency in EAF dephosphorization. It was found that this parameter presents a high correlation, for industrial scale, with the dephosphorization efficiency and can be used to predict which slag will be the most efficient. The temperature, in the analyzed range, does not seem to be a directly relevant factor in the efficiency of dephosphorization. On the other hand, the viscosity of the slag showed significant weight in the calculation of the efficiency using the parameter (FDep).