Combustion characteristics and efficiency of raw and clean lignite samples by thermal analysis techniques: TG–DTG–MID, DSC, and PDSC applications

Abstract This study investigates the combustion characteristics and efficiency of six distinct lignite samples, comparing their untreated and treated forms. The experimental approach employs simultaneous thermogravimetry coupled with multiple ion detection (TG–DTG–MID) as well as differential and pressurized scanning calorimetry (DSC–PDSC) techniques. This integrated methodology provides a thorough understanding of the combustion mechanisms involved. The experiments are conducted under a controlled heating rate of 10 °C min −1 across a broad temperature range of 25 to 650 °C. Additionally, PDSC assessments are performed under varying pressure conditions, ranging from 100 to 300 psig, while maintaining the same heating rate. Distinct reaction phases such as evaporation, primary carbonization, and mineral matter decomposition are identified through detailed analyses of the untreated and treated lignite samples. Key combustibility indices, including reactivity and the ignition–combustion index, are systematically evaluated for both untreated and treated specimens. These metrics offer valuable insights into the combustion behavior and efficiency of the lignite samples under different treatment conditions.