GB714160A - A method for the continuous refining of fatty oils with an inorganic acid - Google Patents

Abstract

In a process for decolourizing fatty oils, the oil is continuously mixed with an inorganic acid such as sulphuric acid, the acid sludge is separated by centrifuging and the inorganic acid remaining in the oil is then neutralized by adding a salt of a weak acid. The oil may be finally centrifuged to remove the products of neutralization. The salt of a weak acid is preferably an alkali metal or ammonium salt, such as the carbonate or bicarbonate. It is preferred to use concentrated acid unless the oil contains a high percentage of free fatty acids, in which case dilute acid of not less than 60 per cent. concentration may be used. Instead of using dilute acid the oil may be contacted first with concentrated acid and then with water, for instance by adding water dispersed in decolourized oil to the mixture of oil and concentrated acid, or the concentrated acid may be added to the oil which has the required amount of water dispersed therein. If the free fatty acid content of the oil is high, the acids are preferably neutralized with alkali and the soap separated before the oil is decolourized as described above. Any acid sludge remaining in the oil after the decolourizing treatment may be eliminated by adsorption on a bleaching earth, and any remaining fatty acids may be neutralized with alkali. When oils containing mucilaginous substances such as lecithin are to be treated, these substances may be first removed, and soya oil may be de-slimed before decolourization. Oils specified for treatment include rape seed oil and oils obtained by extraction with volatile hydrocarbons, the latter being refined, if desired, as a solution of oil in light hydrocarbons. Specification 481,580 is referred to.