Particle size reduction experiments were
conducted in two stages: (1) a chopper without a screen, and (2) a hammer mill using
three screen sizes (19.05, 25.4, and 31.75 mm). The lowest grinding energy (1.96 and
2.91 kWh t1) was recorded for canola straw using a chopper and hammer mill with
19.05-mm screen size, whereas the highest (3.15 and 8.05 kWh t1) was recorded for barley
and oat straws. The physical properties (geometric mean particle diameter, bulk, tapped
and particle density, and porosity) of the chopped and hammer-milled wheat, barley,
canola, and oat straw grinds measured were in the range of 0.98e4.22 mm, 36e80 kg m3,
49e119 kg m3, 600e1220 kg m3, and 0.9e0.96, respectively. The average mean particle
diameter was highest for the chopped wheat straw (4.22-mm) and lowest for the canola
grind (0.98-mm). The canola grinds produced using the hammer mill (19.05-mm screen
size) had the highest bulk and tapped density of about 80 and 119 kg m3; whereas, the
wheat and oat grinds had the lowest of about 58 and 88e90 kg m3. The results indicate
that the bulk and tapped densities are inversely proportional to the particle size of the
grinds. The flow properties of the grinds calculated are better for chopped straws compared
to hammer milled using smaller screen size (19.05 mm).
Particle size reduction experiments wereconducted in two stages: (1) a chopper without a screen, and (2) a hammer mill usingthree screen sizes (19.05, 25.4, and 31.75 mm). The lowest grinding energy (1.96 and2.91 kWh t1) was recorded for canola straw using a chopper and hammer mill with19.05-mm screen size, whereas the highest (3.15 and 8.05 kWh t1) was recorded for barleyand oat straws. The physical properties (geometric mean particle diameter, bulk, tappedand particle density, and porosity) of the chopped and hammer-milled wheat, barley,canola, and oat straw grinds measured were in the range of 0.98e4.22 mm, 36e80 kg m3,49e119 kg m3, 600e1220 kg m3, and 0.9e0.96, respectively. The average mean particlediameter was highest for the chopped wheat straw (4.22-mm) and lowest for the canolagrind (0.98-mm). The canola grinds produced using the hammer mill (19.05-mm screensize) had the highest bulk and tapped density of about 80 and 119 kg m3; whereas, thewheat and oat grinds had the lowest of about 58 and 88e90 kg m3. The results indicatethat the bulk and tapped densities are inversely proportional to the particle size of thegrinds. The flow properties of the grinds calculated are better for chopped straws comparedto hammer milled using smaller screen size (19.05 mm).
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