Lynne Wong's PhD thesis

Boiling house recovery 91.0 89.8 89.5 90.3 87.9 90.0
Overall recovery 87.8 85.6 86.1 87.1 84.7 87.2
2.1.6 Impact of extraneous matter on milling performance
The influence of increasing levels of dry trash, green leaves and cane tops on the quality of
cane, bagasse, mixed juice and molasses, juice extraction, sugar recovery, CCS, boiling
house recovery and overall recovery are clearly illustrated in Figs 2.7 – 2.22. In most
cases, linear relationships were found. Each of these will now be discussed in turn.
2.1.6.1 Cane quality
The change of pol % cane due to increasing levels of extraneous matter (Fig 2.7) clearly
shows that each unit increase in dry trash (D) causes a 0.13 unit decrease in pol % cane.
Similarly, each unit increase in green leaves (G) and tops (T) entails corresponding
decreases of 0.13 and 0.12 in pol % cane, all changes being related to a pol % clean cane
value of 16.7 (Table 2.2). Sucrose % cane which was not determined directly but
calculated from the sucrose contents in mixed juice and bagasse, was affected to different
degrees by the nature of the extraneous matter; the decrease in sucrose % cane is more
severe in the case of dry trash than for green leaves and cane tops (Fig 2.8).
Fibre % cane is markedly increased by dry trash, less so by green leaves and remains
unaffected by cane tops (Fig 2.9), probably because the cane tops used were without
attached foliage. It can be deduced from Fig 2.9 that increases of 2 and 5 units in fibre %
cane mentioned in Chapter 1 are in fact due to the presence of about 3.5% and 8.5% dry
trash respectively.
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