Lynne Wong's PhD thesis

The effect of soil on factory performance has been the subject of investigation by Muller et
al. (1982) who found that, through a material balance of ash in the factory, 40% of the soil
present in cane goes to the juice and 60% to the bagasse.
1.5.2 Effects of tops and trash on cane processing
St Antoine (1977) stated that cane tops contain relatively little sucrose and a high
proportion of non-sugars and a juice of relatively low purity, hence entails a high
production of molasses. He also reported that cane leaves absorb a certain quantity of juice
during crushing and increase sucrose loss in bagasse. They tend to make the mill roll slip,
and reduce mill extraction. Cane leaves, especially green ones, contain soluble non-sugars
which increase sucrose loss in molasses.
Lamusse and Munsamy (1979) and Cargill (1976) showed that high extraneous matter in
cane increases transportation costs, reduces mill throughput and increases sucrose losses.
Clarke (2003) stated that these losses occur in bagasse, and in the boiling house due to the
extraction from the trash of non-sucrose materials that interfere with clarification and
sucrose crystallisation.
The traditional method of reducing extraneous matter of cane, namely burning, has become
unacceptable because of the environmental consequences (Bernhardt, 1994). Since trash
has the benefit of providing additional biomass fuel for steam generation and power
production, it could be collected separately from the field or separated from the cane upon
arrival at the mill.
Dry cane cleaning is now a means of removing a significant proportion of this material
before the cane is shredded, thus avoiding the detrimental effects it has on cane processing.
Dry cleaning also provides the potential of supplying large quantities of energy-rich fibre
for steam generation and power production for off-crop refining, by-product manufacture
or supply to the national grid. Bernhardt (1994) has reviewed in detail various methods of
dry-cleaning sugar cane.
For each 1% increase in trash, Keller and Schaffer (1951) showed that fibre % cane is
increased by 2.75%, as confirmed by Cargill (1976) in Natal; Blanchi & Keller (1952)
showed that mill extraction is reduced by 0.40%; Cargill (1976) in South Africa found that
the crushing rate is reduced by 3%; and Tsai Ming Chuin (1973) indicated that the overall
recovery is reduced by 0.34%.
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