refining of sugar cane

1. Refining of sugar cane
 A sugar refinery is a refinery which processes raw
sugar into white refined sugar.
Refining process consists of these steps:
o Affination
o Carbonation
o Char filtration
o Decolorization
o Crystallization
o drying
o storage

2. Affination:
 dissolving off some surface impurities.
 washing the sugar with warm suryp to loosen the
molasses film.
 separation of the crystals from the syrup in a centrifugal
 washing of the separated crystals with hot water.
 The resultant syrup is passed through a screen to remove
any particulate in it.
 The syrup from the crystal washing, is called affination
syrup.
 The syrup volume is reduced to form the massecuite.
 The separated liquor is blackstrap molasses.

3.  Two clarification methods are commonly used:
 The phosphatation uses phosphoric acid, lime and
polyacrylamide flocculent to produce a calcium
phosphate floc.
 Carbonation consists of adding lime to the raw Melter
liquid and then bubbling carbon dioxide (CO2) through
the liquor to produce a calcium carbonate precipitate.
 The next step is decolorization, which removes soluble
impurities by adsorption.
 The two most common adsorbents are granular
activated carbon and bone char.
 Activated carbon are used in either fixed or moving
bed systems.

4.  the bone char consist of activated carbon on calcium
skeleton.
It has high surface area and ability to absorb color and
inorganic ash impurities from sugar.
 the liquor is stored in a long vertical and cylindrical
vessel about 36 hours.
The vessel is already packed with bone char, where
bone char and liquor comes in contact, resulting
impurities and color are absorbed by bone char.
This is now ready for final refining and recovery step,
which is achieved by crystallization in vacuum pans.

5.  The sugar liquor from the evaporators (thick juice) is
transferred to the vacuum pans to further reduce the
liquor volume and form the massecuite.
 the most common boiling system is the four-strike
system.
 After boiling, the sugar is dried with granulator.
 And then it is screened, the refined granulated sugar is
sent to conditioning bins and then to storage bins.