Bleaching is the process operation which is carried out before deodorisation.
In addition to colouring matters, the bleaching treatment using actived earth will remove residual phosphatides, metals, soaps and oxidation products.
Bleaching in 3 stages
Bleaching is performed in 3 stages :
Initial mixing of oil with bleaching earth under controlled conditions of temperature, acidity and humidity for a specific residence time.
Secondly the oil is heated under vacuum with sparge steam to ensure proper mixing with bleaching earth for a specific residence time.
Finally the mixture is pumped through hermetic leaf filters with stainless steel mesh elements followed by polishing filtration.
Spent cake is dried by steam blowing to remove the oil from the wet cake.