Blending PCI Coal and Biochar as Sustainable Alternative for Blast Furnace Fuels

Abstract

The aim of this study was to investigate the feasibility of using biochar or its blends with pulverized coal injection (PCI) coal as a potential blast furnace (BF) fuel. A comparison was conducted between the properties of biochar obtained from the pyrolysis of coconut shell and PCI coal. Coconut shells were pyrolyzed at different temperatures (between 200 °C and 450 °C) to produce biochar. The physicochemical characteristics and combustion indices of the materials were evaluated. Combustion rate was also studied using thermogravimetric analysis (TGA) to determine the effect of biochar addition on the PCI coal. Based on the combustion indices (Tmax, DTGmax, biochar yield at Tmax, and residue at 900 °C) and the three-stage thermal decomposition behavior observed in the TG/DTG analysis, it was found that biochars produced at low pyrolysis temperatures exhibited suitable characteristics for use as an auxiliary fuel in the BF. It was also observed that biochar had a higher alkalinity index (AI = 32.40) compared to the reference PCI coals (AI = 3.08 and 2.06). The results suggested that the addition of biochar coal increases the combustion rate of the resulting blends. Blends containing 10%, 30%, and 50% biochar (C200) were evaluated, corresponding to biochar/PCI coal ratios of 10/90, 30/70, and 50/50, respectively. Although biochar cannot be used as a complete replacement of PCI coal in a BF, the blend containing 30% biochar and 70% PCI coal (30% C200) showed promising performance without significantly altering fuel characteristics, demonstrating the potential of an integrated approach combining physicochemical characterization, combustion behavior, and blend performance for PCI applications.