Image and Sieve Analysis of Biomass Particle Sizes and Separation after Size Reduction

Improved physical separation of biomass concentrates higher-value components, returns unused plant components to the soil, and provides a more efficient platform for downstream industrial users. Sieving and Image Analysis (IA) were studied to evaluate biomass particle sizes, particle size distribution, and potential separation of biomass materials. Switchgrass, wheat straw, and corn stover were used in the study. Particles prepared by a knife mill equipped with various screen sizes were subject to sieving test and IA. Results showed that all three biomass materials would be analyzed using the fast, easy and accurate IA. Biomass particle physical properties, such as length, width, and projected area were obtained through IA. There were 25 to 30 % of switchgrass, prepared by larger knife mill screen, with node sections presented on the 19.0 mm sieve compared with 17.5 % nodal particle population average. This difference suggests that larger screen installed in the knife mill would be used to produce particles with optimum sizes for the nodes separation from the internodes. Results also show that a factor of 4~5 is suggested to apply to the Geometric Mean Diameter (GMD) calculated by standard sieving test to accurately represent the true particle length for grass-like biomass materials. It suggested that standard summary statistics calculated by various consensus standards may not provide the greatest accuracy for biomass.

Keywords: biomass material, sieving, particle size distribution, separation, geometric mean diameter, image analysis.