**Leo S. Carlsson \*, Peter B. Samuelsson and Pär G. Jönsson**

Royal Institute of Technology , Brinellvägen 23, 114 28 Stockholm, Sweden; petersam@kth.se (P.B.S.); parj@kth.se (P.G.J.)

**\*** Correspondence: leoc@kth.se

Received: 29 July 2020; Accepted: 24 August 2020; Published: 26 August 2020

**Abstract:** The melting time of scrap is a factor that affects the Electrical Energy (EE) consumption of the Electric Arc Furnace (EAF) process. The EE consumption itself stands for most of the total energy consumption during the process. Three distinct representations of scrap, based partly on the apparent density and shape of scrap, were created to investigate the effect of scrap on the accuracy of a statistical model predicting the EE consumption of an EAF. Shapley Additive Explanations (SHAP) was used as a tool to investigate the effects by each scrap category on each prediction of a selected model. The scrap representation based on the shape of scrap consistently resulted in the best performing models while all models using any of the scrap representations performed better than the ones without any scrap representation. These results were consistent for all four distinct and separately used cleaning strategies on the data set governing the models. In addition, some of the main scrap categories contributed to the model prediction of EE in accordance with the expectations and experience of the plant engineers. The results provide significant evidence that a well-chosen scrap categorization is important to improve a statistical model predicting the EE and that experience on the specific EAF under study is essential to evaluate the practical usefulness of the model.

**Keywords:** electrical energy consumption; Electric Arc Furnace; scrap melting; statistical modeling
