Hydrothermal carbonization of waste furniture for clean blast furnace fuel production: Physicochemical, gasification characteristics and conversion mechanism investigation

This study aimed to investigate the physical and chemical characteristics of hydrochar derived from waste furniture through hydrothermal carbonization (HTC) and evaluate its suitability as a fuel for blast furnace injection, the formation mechanism of biomass conversion to hydrochar was also systematically investigated. The optimal HTC conditions were determined as 260 degrees C, liquid-solid mass ratio of 2:1. The resulting hydrochar exhibited a high calorific value of 27.78 MJ/kg, a specific surface area (St) of 3.01 m2/g, and K and Na concentrations of 203 mg/kg and 416 mg/kg, respectively. The apparent activation energy (E) for gasification was measured as 154.54 kJ/mol, indicating its potential as a clean injection fuel for blast furnaces. During HTC, cellulose, hemicellulose, and lignin underwent hydrolysis, decarboxylation, polymerization, and aromatization processes, resulting in the transformation of water-soluble small molecules into polymerized hydrochar and water-insoluble large molecules into polyaromatic hydrochar. This study provides insights into the possibility of replacing fossil fuels in the blast furnace iron-making process.