GB707224A - Process for recovering oils, fats or waxes from spent absorbent materials - Google Patents

Abstract

Oils, fats and waxes are recovered from earthy absorbent materials, such as Fuller's earth, used in refining them, by heating the absorbent material at atmospheric pressure, in the presence of a detergent, with an aqueous solution of an alkali, or an alkali-metal salt which reacts alkaline to phenolphthalein or a combination of these, the amount of alkali, alkali-metal salt or combination thereof being sufficient to react with the absorbent material, and removing the separated oil, fat or wax from the mixture. The alkali or alkali-metal salt reacts completely with the reactive metallic constituents of the earth to alter its nature so that it is no longer capable of absorbing oily matter. The detergent may be a synthetic detergent or a soap. The latter may be formed in situ by partial saponification of fatty oil or free fatty acid contained in the earthy absorbent material. The alkalies or alkali-metal salts preferred comprise sodium carbonate or caustic soda. The alkali or alkali-metal salts is usually present in amount less than 10 per cent. of the weight of the earthy absorbent material. In the case of saponifiable oils using caustic soda, the calculated quantity of alkali is added at 60 DEG C. until disintegration of the abosrbent is complete and in the presence of water in amount from 2 to 4 times the weight of earth, followed by the addition of a further quantity of the alkali sufficient to produce the necessary soap to cause separation of the oil whilst the temperature is raised to 100 DEG C. The soapy liquor is drawn off and acidified to recover its fatty content. In examples, the treated earths contain viscous lubricating oil, tallow, lard, cod liver oil and rape oil.