GB707385A - Improvements in or relating to the solvent extraction of fatty oil, fat and wax fromsolid matter of animal or vegetable origin, and apparatus therefor - Google Patents

Abstract

<PICT:0707385/III/1> Fats, fatty oils and waxes are extracted from solid particles of vegetable and animal (including fish and marine animal) materials with the aid of an organic solvent, employing a solvent to solute ratio by volume not substantially greater than 1.5 : 1, to produce a miscella of at least 40 per cent. solute content by volume. In calculating the solvent to solute ratio, that portion of the solvent which is retained by the exhausted solids upon separation of the miscella is excluded. Vegetable and animal materials mentioned are maize, maize germ, cottonseed, soyabean, sesame seed, rapeseed, coconut meat, linseed, groundnuts, sunflower seed, palm kernel, copra and oil cakes therefrom, whale, fish and/or parts therefrom, suet, hides and bones. Organic solvents mentioned are solvent naphtha, petroleum naphtha, n-hexane, n-heptane, mixed octanes, trichlorethylene, ethylene dichloride, methyl chloride, carbon disulphide, acetone, ethyl ether or mixtures thereof. If insufficient fibrous material is present to facilitate separation of the miscella from the residue, this fibrous material may be added, for example in the form of bran, husks, chaff, straw, or asbestos. The process may be carried out in the apparatus shown in the drawing, wherein the material to be extracted is taken from storage bin 1 and reduced to a suitable size by means of rollers 3. The comminuted material passes through line 5 to loading device 7, from which it passes into the basket of the centrifugal solvent extractor 8. Fresh solvent is contained in tank 9, while miscellae of decreasing concentration are contained in tanks 10, 10a, 10b and 10c. Solvent or miscellae pass from these tanks to the extractor 8 through lines 11, 11a, 11b, 11c and 12, and miscellae are returned to the tanks through pump 16 and line 17. Extracted meal is removed from the centrifuge basket and passed via duct 24 to bin 25 and then via duct 26 to drier 27, the vapours from which pass to a solvent recovery system. In operation, concentrated miscella from tank 10 is passed to extractor 8 and recycled to tank, this circulation being continued as long as economic. The same procedure is adopted in turn with miscellae from tanks 10a, 10b and 10c and finally with pure solvent from tank 9. When the extraction is complete, miscella from tank 10 is passed via line 23 to the solvent recovery system for separation of extract and solvent, while the contents of tank 10a are transferred to tank 10. Similarly, miscella is passed from tank 10b into tank 10a, from tank 10c into tank 10b and from tank 9 into 10c, while fresh solvent is passed into tank 9. The system is then ready to commence a new extraction. Instead of a five-stage extraction, employing the five tanks 10, 10a, 10b, 10c, 9, the extraction may be conducted in any desired number of stages. In the examples, (1) and (4) corn germ meal is extracted with n-hexane or trichlorethylene in five stages, (2) and (3) soyabean or cottonseed meal is extracted with n-hexane in four stages, and (5) corn germ meal is extracted with n-hexane in seven stages.