Roll press compaction of corn stover and perennial grasses to increase bulk density

Abstract

The objective of this study was to investigate roll press compaction of coarsely ground corn stover and native perennial grasses to produce compacted products with a bulk density of at least 240 kg m−3 for effective truck transport. A pilot-scale roll press compaction machine (520.7 mm roll diameter and 127.0 mm roll width) was used to compress corn stover and perennial grasses (moisture contents of 10% to 18% wet basis) ground in a tub-grinder with three round-hole screen opening sizes (25.4, 76.2, and 127.0 mm). Bulk density of compacted materials (i.e., compacts) ranged from 263 kg m−3 to 365 kg m−3 for the roll compaction forces of 214–534 kN. Durability (tumbling test) of compacts ranged from 61% to 92%. Specific energy consumption (excluding no-load machine energy) for the roll press compaction ranged from 19 MJ Mg−1 to 339 MJ Mg−1. The results from this study would be useful for developing a biomass supply logistics system involving coarse-grinding followed by roll press compaction of biomass bales.