Raw juice extracted by roller mills is impure and needs to be clarified to remove solid suspensions. Purification involves the formation of precipitates via the reaction of lime with substances present in the juice. Sulfur eliminates colorant material.
Milk of lime or lime slurry makes the flocculation of colloidal substances easier, raises pH to 6.8 – 7.0 and promotes the formation of calcium salts from the juice’s natural acid. Once deposited at the bottom of the clarifier, these salts attract other impurities in the suspension. It is best to carry out the clarification process when the final pH is around neutrality so that sucrose molecules are preserved.