Torrefaction and carbonization of refuse derived fuel: Char characterization and evaluation of gaseous and liquid emissions

•Thermochemical upgrading of RDF was evaluated at a semi-industrial scale.•RDF chars had higher carbon content, fixed carbon and calorific value than raw RDF.•Water extraction improved RDF char properties and reduced chlorine content.•Liquid products were rich in organic compounds such as acids, phenols and furans. Refuse derived fuel containing non-hazardous industrial wastes was subjected to torrefaction and carbonization in an industrial furnace. The RDF samples were heated at 300 °C and 400 °C, for 30 min, yielding solid products (chars) as well as gases and liquids. Proximate and ultimate composition, mineral composition, chlorine content and high heating value were determined for the original sample and the produced chars. Thermal treatment produced RDF chars with carbon contents of 61.6 and 80.2 wt%, and high heating values of 19.9 and 23.5 MJ/kg, that could be further upgraded by washing with water to reduce ash and chlorine concentrations and improve calorific value. Gas products were composed of carbon dioxide and carbon monoxide with minor amounts of hydrogen. Methane was only detected in the gas produced at 400 °C. The process generated liquid products rich in organic compounds that represent potential in further energy or material recovery.