ICUMSA has classified sugar into several categories. The highest grade is grade A which has very tight standard. Partial requirements of this standard are as following:
ICUMSA : 45 RBU
Polarization : 99.80% Min
Ash content : 0.04% Max
To reach the above parameters it is necessary to process the sugar with further step as following:
Affination is a process of mixing unrefined sugar crystal with slightly higher purity sugar syrup in warm condition. This is to remove the layer of mother liquor surrounding unrefined crystal. Then, the slurry is centrifuged to remove mother liquor with higher impurities content. Later, wet crystal product is dissolved before processed in the next step.
This step is the same as clarification process in ordinary sugar factory. However, the process use is usually carbonatation. Sulphitation method shall be avoided as it is required to have insignificant amount of Sulphur.
In decolorization process, color and inorganic materials will be removed. There are two common methods for this process. One is using active carbon and the other is using ion exchange resin. Active carbon has advantages of higher color removal and easy to regenerate. While ion exchange resin has better inorganic material removal. The regeneration of ion exchange resin is using chemical substance thus it needs more safety attention. However, active carbon regeneration is more energy consuming.
Thus, some of refinery factories employ both method in series. The solution is fed to a vessel with active carbon bed inside, then followed by processing the solution inside a vessel with ion exchange resin bed. All the process is a semi-batch process, where several vessels run the process while the others undergo regeneration process.
After decolorization process, sugar solution (juice) will undergo the same process as describe in previous article.
- Separation and Drying