Sugar Production from Sugar Cane
Practical Action
Moulding and packaging
For syrup production the juice is poured or ladled from the boiling pan into containers where it is
allowed to cool. For lump sugar production, the massecuite is poured into cooling trays where it
is stirred to promote even cooling and crystallisation. Upon setting, the lump sugar is cut or
moulded into shapes to suit the local market and customer requirements. Alternatively, before
the massecuite solidifies it can be poured into pots or moulds to produce various shapes.
In Bangladesh where small temporary factories are common the pan is removed from the furnace
allowing cooling and crystallisation to occur within the pan while a new pan with fresh juice is
placed on the furnace.
Production methods for granular sugars
Medium-scale production of white and brown granular sugars can be undertaken using either the
open pan (OP) or vacuum pan (VP) processes. These processes use more complex technology
than used for jaggery and syrup production. Open pan sulphitation (OPS) is probably the most
common open pan method. In each case the production process can be divided into six stages:
Extraction of juice from the cane
Clarification of the juice
Boiling of the juice
Crystallisation
Centrifuging
Drying and packaging
Open Pan Sulphitation (OPS) sugar processing
Developed in India during the 1950s for the production of white granular sugar, OPS is based on
an upgrade of khandsari production. The technology uses a mix of traditional and scaled-down
versions of modern sugar technologies and is ideally suited to processing between 100 and 500
tonnes of sugar cane per day, with recovery rates of between 5 and 8%.
Unlike large-scale sugar factories, OPS plants do not usually have their own estates to supply
cane but rely instead on contractual agreements between local growers and the factory. This
level of technology can be beneficial to rural communities by creating employment opportunities
at the factory and providing income for cane growers in the area.
Since the introduction of the technology, large numbers of OPS sugar plants have been built
throughout India, with estimates of several thousand still in use by the late 1980s.
Dissemination of the technology outside the South Asia has been limited; however, the potential
for OPS is considerable in countries that produce non-crystalline sugars (jaggery, gur, panela,
muscovado, etc) as they already have some of the necessary expertise.
Extraction
The cane is usually shredded before crushing using two or three 3-roll mill tandem arrangements
either electrically or diesel engine powered. The crushers can be hydraulic loaded to improve
extraction rates which can be as high as 70% of the available juice.
Clarification
Chemical clarification, based on modern cold lime sulphitation, is carried out to remove
impurities which inhibit the formation of the crystals and can discolour the final product. The
addition of lime also has the advantage of reducing the natural acidity of the cane juice, limiting
the formation of invert sugars.
Batches of juice are treated simultaneously with milk of lime (CaO) and sulphur dioxide (SO2)
(by air forced through a sulphur furnace) after which the juice is transferred to an open boiling
pan and quickly heated to 90ºC or above. The lime and heat treatment form a heavy precipitant
that flocculates, carrying with it most of the suspended impurities in the juice. The juice is then
filtered and allowed to settle. The clear juice is decanted and transferred to the boiling furnaces.
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