Mechanical strength and combustion properties of biomass pellets prepared with coal tar residue as a binder

To reutilise the hazardous waste material coal tar residue (CTR) to bring environmental and economic benefits, CTR was first used as a binder to prepare biomass pellets with enhanced mechanical strength and heating values. CTR, which mainly contained asphaltenes (40.06%), aliphatics, aromatics and non-hydrocarbon components, had a high viscosity (72,276 mPa·s) and heating value (27.46 MJ/kg). When the CTR percentage increased from 0 to 40 wt%, the abrasive resistance of wheat straw, sawdust and moso bamboo pellets significantly increased from 10.62-69.20% to 95.66-98.24%, while their water resistance time increased from 6 s to >30 min and their heating value increased by 20.62-25.96%. The ignition temperature of wheat straw pellets increased from 275.7 to 280.7 °C as the CTR content increased from 0 to 30 wt%, whereas the maximum burning rate decreased from 1.28 to 0.82 mg/min and the burnout temperature increased from 465.33 to 563.33 °C.