Lynne Wong's PhD thesis

Figure 1.3. Cane sampling by core sampler for analysis.
1.2.3 Juice extraction
The cane is first prepared by revolving knives that cut the stalks into chips which are then
cut by heavy duty shredder into long fibres before entering the milling plant. The latter
consists of multiple units (4 – 7) of three-roller combinations through which the crushed
cane or the cellulosic fibre (bagasse) successively passes. Fresh water is sprayed on the
mat of bagasse as it enters the last mill to help leach out the maximum sugar. In this
context, the thin juice extracted by each mill is sprayed on the bagasse entering the
previous mill. This process is termed imbibition, and the water used, imbibition or
maceration water. The combined juice collected after the first mill is called mixed juice.
The fibre from the last mill, the final bagasse, contains unextracted sugar and 45 – 55%
moisture. Bagasse normally goes to the boiler plant as fuel to produce steam and
electricity for the factory's own demand. The surplus bagasse can be used to produce
electricity for the national grid.
1.2.4 Clarification and filtration
The mixed juice extracted from the cane is acidic in nature, of pH about 5.2; it consists of
a solution of sucrose mixed with soluble and insoluble impurities. The clarification (or
defecation) process removes most of the turbid impurities by the action of heat and lime.
The mixed juice is heated, in most cases, to about 75 °C, and the juice pH is changed from
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