Characterization, leachability and valorization through combustion of residual chars from gasification of coals with pine

► The environmental toxicity of char residues was evaluated through leaching tests. ► Low toxicity levels detected reveal that chars have good potential for valorization. ► Fluidized bed combustion experiments were applied to char residues. ► Emission of some pollutants was controlled during combustion assays. ► Leaching tests were performed to evaluate environmental toxicity of ashes produced during fluidized bed combustion.