Fuel pellet production from corn crop residue at semi-industrial scale: Effects of residue type, initial moisture content and process variables on pellet quality

Corn crop residue is an abundant lignocellulosic feedstock for non-woody pellet production, yet the combined effect of raw material and pelletisation operating parameters on pellet quality and ISO 17225-6:2021 compliance remains unaddressed within a single semi-industrial framework. The influence of residue type, initial moisture content, input mass flow and added water on pellet physical and mechanical properties was evaluated in a flat-die semi-industrial pellet mill. Pellets were characterised for moisture content, length, diameter, bulk density and durability. Sample type dominated pellet quality responses. Corn stover pellets at 10% initial moisture failed to meet the Class B threshold under any condition (mean durability 85.64%). Corn cob pellets at 15% initial moisture reached Class B in only five scenarios (mean durability 91.94%). Corn cob pellets at 12.5% initial moisture showed the best performance, with mean bulk density of 760.08 kg/m 3 , moisture content of 8.49% and durability of 95.67%, meeting Class A or B requirements in 24 of the 31 scenarios evaluated. Best-performing conditions were identified at mass flow rates of 5.03–7.70 g/s and added water of 0.87–0.95 g/s. Feedstock selection and moisture preconditioning proved crucial for high-quality pellet production scalable to industrial conditions.