Steel Recarburization by Densified and Nondensified Biochar as a Carburizing Agent in Electric Arc Furnace‐Based Steelmaking

This article studies steel recarburization utilizing densified walnut shell (WS) biochar as a carburizing agent compared with loose wood biochar and fossil carbon sources, namely anthracite and blast furnace (BF) coke, under laboratory conditions at 1650 °C using the carburizer cover method. The recarburization process is characterized by two stages in the carbon dissolution rate. The initial stage starts rapidly and is followed by a slower stage. Using BF coke, the melt has the highest final carbon content at 2.790 wt%, and carbon recovery of 87.6%. Densified WS biochar shows an initial dissolution rate constant of 7.94 × 10 −4 s −1 , comparable to the BF coke case of 7.66 × 10 −4 s −1 . However, its initial stage duration is shorter, and the final carbon content of the melt is 1.520 wt%, with a carbon recovery of 51.1%. Anthracite and loose wood biochar perform the lowest with final carbon content in the melt at 1.280 and 1.210 wt% and carbon recovery of 46.5% and 40.3%, respectively. The results show changes in melt composition, with increases in silicon when BF coke, anthracite, and densified WS biochar are used. Sulfur transfer is noteworthy only for BF coke. Phosphorus transfer is minimal regardless of the carbon source.