Model studies on the effects of composition differences of direct reduction pellets and an adaptive addition of slag formers for the EAFprocess

Sammanfattning: This work has been conducted to study the effect of different types of iron ore pellets on an EAFbased steel production. The study has focused on how the chemical composition of the raw materialsinfluences the slag amount and as a result the EAF operation. It is also shown that the raw materialselection can be optimized for a better slag practice. The advantage of slag former additions that arestrictly adapted to the EAF charge composition is also demonstrated.This work is based on a MgO-saturation model for slag, developed by Dr Roger Selin. The model hasbeen implemented in RAWMATMIX®, a software developed by Kobolde & Partners AB in Stockholm.In this report I discuss the following studies: i) A study and comparison between different basicityindices and MgO-saturation for EAF slags, ii) a comparison between different DR-pellets and mixesbetween them and their corresponding DRI, iii) a parameter study on how different properties for theDR-pellet and DRI influence the EAF process, and iv) a case study of two hypothetical steel plants toillustrate the value of an adaptive slag former addition based on the raw material input. Overall,these studies describe the value of using DRI based on DR-pellets, containing low amount of acidicoxides and balanced amounts of MgO, for an EAF based steel production.