Patent GB-628879-A (GB)
Title: Improvements in or relating to method and apparatus for extracting pigments from fatty materials
Filed: 1946-08-14
Abstract: Soap is produced as a valuable by-product in the extraction of pigments such as carotene from saponifiable fatty materials by saponifying them at a reduced pressure such as to maintain the temperature below the decomposition point of the pigment, and extraction of the resulting soap with an extracting solvent for the pigment.  The extraction is carried out in closed apparatus maintained at reduced pressure throughout.  Apparatus according to the invention comprises an extraction vessel 10 with valved connections to a fatty oil container 11, caustic alkali container 14, solvent tank 25, extract tank 31, evaporator 51, condensers 21, 46, and 55, dust trap 23, pumps 28 and 34, receiving tanks 39 and 48, and vacuum pump 17.  A finishing still 57, condenser 59, and receiving tank 62 may be included in the circuit.  As applied to the treatment of palm oil, the melted oil is drawn by vacuum from the vessel 11 into the extraction vessel 10, and a corresponding amount of fifty per cent aqueous caustic alkali is similarly introduced from the vessel 14.  Heat is generated by the saponification reaction, but the temperature is kept below 80 DEG  C., the decomposition temperature of carotene, by maintaining the pressure below 355 mm. of mercury, the pressure at which water boils at 80 DEG  C., or a considerably lower pressure.  Windows w are provided in the dome cover of the vessel for observation of any tendency to foam, for which the vacuum is momentarily released by opening valve 10b.  An agitator and scraper rotates within the vessel 10 to mix the contents and advance the material towards the discharge ports.  Steam is rapidly eliminated from the soap mass producing a fine dry powder.  When saponification <PICT:0628879/III/1> is complete, and the soap completely powdered, agitation is discontinued and a solvent such as benzene, nitrobenzene, ethylene dichloride, or petroleum ether drawn in from the tank 25.  Vacuum is discontinued and agitation recommenced for about 15 minutes, whereupon the mass is allowed to settle and the extract drawn to the tank 31.  Fresh solvent for another wash may then be introduced and the process repeated if necessary.  After the extraction of the pigment from the oil, the soap is dried under vacuum in the vessel and discharged, whereupon a new batch of oil is introduced and the cycle repeated.  With oils and fats which have a tendency to form a soft soap it is desirable to employ a quantity of alkali greater than theoretically needed whereby a harder soap having better powdering characteristics is produced. In the use of palm oil, 20 per cent more than the theoretical quantity of caustic alkali is desirable.  The carotene solution is concentrated in an evaporator 51 and still 57 (see Group IV (c)).ALSO:A process of extracting pigments such as carotene from saponified fatty materials comprises saponifying the fatty material at reduced pressure so as to avoid decomposition of the pigment by rise of temperature and extraction of the resulting soap with a solvent.  The extraction is carried out in closed apparatus maintained at reduced pressure throughout.  An apparatus according to the invention comprises an extraction vessel 10 with valved connections to a fatty oil container 11, caustic alkali container 14, solvent tank 25, extract tank 31, evaporator 51, condensers 21, 46 and 55, dust-trap 23, pumps 28 and 34, receiving tanks 39 and 48, and vacuum pump 17.  A finishing still 57, condenser 59, and receiving tank 62 may be included in the circuit.  As applied to the teatment of palm oil, the melted oil is drawn-by vacuum from the vessel 11 into the extraction vessel 10 and a corresponding amount of fifty per cent aqueous caustic alkali is similarly introduced from the vessel 14. Heat is generated by the saponification reaction, but the temperature is kept below 80 DEG  C., the decomposition temperature of carotene, by maintaining the pressure below 355 mm. of mercury, the pressure at which water boils at 80 DEG  C., or a considerably lower pressure.  Windows w are provided in the dome cover of the vessel for observation of any tendency to foam for which the vacuum is momentarily released by opening valve 10b.  An agitator and scraper rotates within the vessel 10 to mix the contents and advance the material towards the discharge ports. Steam is rapidly eliminated from the soap mass, producing a fine dry powder.  When saponification is complete, and the soap completely powdered, agitation is discontinued and a solvent such as benzene, nitrobenzene, ethylene dichloride, or petroleum ether drawn in from the tank 25.  Vacuum is discontinued and agitation recommenced for about 15 minutes, whereupon the mass is allowed to settle and the extract drawn off to the tank 31.  Fresh solvent for another wash may then be introduced and the process repeated if necessary.  After the extraction of the pigment from the oil, the soap is dried under vacuum in the vessel and discharged, whereupon a new batch of oil is introduced and the cycle repeated. With oils and fats which have a tendency to form a soft soap it is desirable to employ a quantity of alkali greater than that theoretically needed, whereby a harder soap having better powdering characteristics is produced.  In the case of palm oil, 20 per cent more than the theoretical quantity of caustic alkali is desirable.  The extract from the tank 31 is concentrated in the evaporator 51, cooled, and a certain amount of soap which is thereby deposited filtered off.  The carotene solution is passed to the finishing still 57 where it is concentrated by steam distillation under vacuum and final storage under nitrogen.