Effects of partial lignin extraction on rheological characteristics and combustion performance of high solids bamboo kraft black liquor

Abstract This study investigates the impact of lignin extraction on the rheological and combustion properties of high-solids bamboo kraft black liquor (BKBL), focusing on viscosity reduction and silicon interference mitigation. Lignin was extracted from BKBL using CO 2 acid precipitation. The effects on viscosity, silicon content, calorific value, and Volumetric Isothermal Expansivity (VIE) were systematically analyzed. Extracting 25 % of lignin reduced the apparent viscosity of BKBL and achieved a 33 % desilication rate. However, this extraction also led to a proportional decrease in calorific value and VIE, with a 15 % extraction resulting in approximately 11 % and 13 % reductions, respectively. An extraction rate of 15–25 % is recommended to balance viscosity reduction and silicon removal with minimal impact on boiler combustion efficiency. This study provides practical insights into optimizing lignin extraction from BKBL, offering significant operational, economic, and environmental benefits for the bamboo kraft pulping industry.