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By-product of sugarcane and use
Sugar mills produce
many by-products of the sugar extraction process, including
bagasse, filter mud, and molasses. A typical sugarcane complex
with a capacity of 3,000 tons per day can produce 345 tons of
sugar, 6,000 liters of alcohol, 3 tons of yeast, 15 tons of
potash fertilizer, 25 tons of pulp, 15 tons of wax, 150 tons
of press-mud fertilizer and 750 kilowatts of power from bagasse.
Molasses
Molasses is the final
effluent obtained in the preparation of sugar by repeated crystallization.
It is the end product of a refining process carried out to yield
sugar. Sucrose and invert sugars constitute a major portion
(40-60%) of molasses.
The yield of molasses in terms of cane processed and sugar produced
displays considerable variation, caused mainly by differences
in the soluble non-sugar content of the juice and in the sugar
recovery procedure of the factory. The yield of molasses per
ton of sugarcane varies from 3.5 to 4.5 percent.
Molasses is mainly
used to manufacture ethyl alcohol (ethanol), yeast and cattle
feed. Ethanol is in turn used to produce portable liquor and
downstream value added chemicals such as acetone, acetic acid,
butanol, acetic anhydride etc. Some of the alcohol-based chemicals,
such as acetic acid and acetone, face stiff competition from
production through the petrochemical route.
The government controls
the export of molasses through export licenses issued every
quarter. Molasses and alcohol-based industries were decontrolled
in 1993 and are being controlled by respective state government
polices.
About 70 percent of
molasses produced is consumed by industrial alcohol manufacturers,
and the remaining 30 percent is consumed by the portable alcohol
sector.
Bagasse
Bagasse is a fibrous
residue of cane stalk that is obtained after crushing and extraction
of juice. It consists of water, fiber and relatively small quantities
of soluble solids. The composition of bagasse varies based on
the variety of sugarcane, maturity of cane, method of harvesting
and the efficiency of the sugar mill. The usual bagasse composition
is given below.
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Composition
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Range(percent)
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| Moisture |
46-52
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| Fiber |
43-52
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| Soluble solids |
2-6
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The utility of bagasse
as fuel depends upon its calorific value, which is affected
by its composition, particularly the moisture content.
Bagasse is usually used as a combustible material in furnaces
to produce steam, which in turn is used to generate power. It
is also used as the raw material for production of paper and
as feed stock for cattle. The present rate of consumption of
bagasse for the manufacture of bleached pulp, various grades
of paper and cardboard is about 500,000 short tons of dry fiber
per year.
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