Fate of phosphorus and potassium in single-pellet thermal conversion of forest residues with a focus on the char composition

The phosphorus and potassium contents of the char obtained from thermal conversion forest residues can limit its utilization as an alternative fuel reducing agent to substitute coal/coke in steelmaking industry. In this study, ash transformation release K P during single-pellet different types (i.e., bark, twigs, bark+twigs) were investigated with aid a vertical tube furnace (Macro-TGA) at temperatures 600, 800, 950 °C) within after stages, i.e., devolatilization gasification. residual before full devolatilization, gasification characterized by SEM-EDS, XRD, ICP-OES support thermochemical equilibrium calculations. concentrations (7970–19500 mg/kg) (1440–4925 produced more than four times higher coke pulverized coal frequently used metallurgical processes. A low amount (?15%) released all fuels. evenly distributed residues, no crystalline compounds containing found. was found K2Ca2(CO3)3, K2Ca(CO3)2. twigs bark+twigs mainly amorphous part ash, most likely form K-Ca rich silicates. Apatite main compound ashes temperatures. Estimations show that 80% is needed for studied assortments reach typical blast coals cokes.