4a. Bleaching
Soap Manufacturing > 4. Raw Materials Treatments
PHYSICAL BLEACHING
The refined oil is pumped into a cylindrical vessel with agitator called "Bleaching Reactor" and kept under vacuum and heated by means of steam. The oil is mixed and treated with bleaching earths that adsorb most of the colour oil. The mixture of oil and bleaching earths is pumped through a filter (Vertical type of press type) for separation. During the bleaching of palm oil, the oil comes out from the filter and passes through heating system, to destroy all the carotenoid pigments. The clear oil obtained is bleached oil. The bleaching level depends from the quantity of bleaching earths used in the process. To increase the bleaching level, the bleached oil is reworked in the bleaching plant. The physical bleaching is used to produce RBD Palm Oil.
CHEMICAL BLEACHING
The refined is pumped into a Chemical Bleaching Reactor. Inside this reactor the oil is heated up to over 90°C by means of a spiral serpentine and is treated with air bubbles for several hours (i.e. 5-6 hours). This is a batch and atmospheric process. The bleached oil is not comparable with the bleached oil obtained with physical bleaching process. This process is used for inedible oils and the bleached oil is used for laundry soap. To produce white soap, it is necessary to use the physical bleaching process.