Table 1
Particle size distribution and bulk density of rice husk (RH).
Particle size diameter, mm Unground RHa wt. % Ground RHb wt. % Two-stage RHc wt. % One-stage RHd wt. %
d 2 29.64 0.00 34.48 0.32
2 < d 0.85 64.91 17.67 29.50 22.05
0.85 < d 0.5 4.15 49.21 1.21 33.77
0.5 < d 0.25 0.86 23.86 0.35 26.74
0.25 < d 0.15 0.29 5.72 0.10 13.43
0.15 < d 0.106 0.05 1.32 0.04 2.41
d < 0.106 0.13 1.86 e 0.46
Density, kg m3 129.6 367.1 102.2 370.6
a The particle size distribution of the two-stage RH used in the present study before grinding. b After grinding with a 2 mm sieve to simulate one-stage milling residues.
c For comparison purposes, the particle size distribution of a Nigerian two-stage RH sample (rice husk only). d One-stage RH sample (rice husk with bran).