Transformation of mineral matter during pyrolysis, gasification and combustion of biosolid chars Alexander Y. Ilyushechkin, San Shwe Hla and Liezl Schoeman Eur. Phys. J. Appl. Phys., 98 (2023) 51 Published online: 12 July 2023 DOI: 10.1051/epjap/2023230035