GB549387A - Improvements in or relating to the manufacture of soap - Google Patents

Abstract

549,387. Manufacture of soap. SHARPLES CORPORATION. June 8, 1940, No. 10059. Convention date, June 29, 1939. [Class 91] Soap is manufactured by a continuous process which comprises passing a fat and a saponifying agent through a mixer, where saponification takes place, to a centrifuge to separate the soap from the aqueous phase. In the preferred modification of the process the saponification takes place in a series of steps, the alkali lye from a succeeding step being used as the saponifying agent in the next preceding stage, with or without an addition of fresh lye. A mutual solvent for the alkali and fat such as ethyl alcohol may be added at the mixing stage if desired. A proportion of rosin or rosin soap may also be added at any stage in the process. The agitation in the mixer stage must be thorough in order to maintain the mixture in a substantially homogeneous condition until it reaches the centrifugation step. The soap phase from the centrifuge is preferably mixed at once with water. An embodiment of the invention is shown in the Figure in which a two-stage process is used. Neutral fat from tank 10 is mixed with partly spent lye from the second stage from tank 13, with the addition if necessary of strong lye from tank 14, in the multi-stage mixer 12. Salt solution is added in the latter stage of the mixer from the tank 16 to assist in the granulating of the separated soap. From the mixer 12 the product is passed to the centrifuge 18 when the soap is separated from the spent lye. The separated soap is at once treated with water from tank 19 to break down the hard outer surfaces of the soap granules and allow the saponifying agent to react with unchanged fat in the second stage of the process. The softened product is now passed to a second multi-stage mixer 23 and again subjected to the action of strong lye from tank 24. The product is grained by the addition of extra lye from pump 26, and passed to centrifuge 27, where the soap and lye are again separated. The halfspent lye is passed back for use in the first stage to tank 13. The soap from centrifuge 27 is again mixed with water in mixer 30, separated in centrifuge 32 and if desired mixed with sodium silicate solution in mixer 34. If desired a three or more stage process may be substituted for the two-stage process described above. It is preferred that the temperature in the mixer 23 should be maintained between 150‹ F. to 200‹ F. to effect the most efficient separation. An example is given of the operation of the process using as starting materials tallow and cocoanut oil. Specifications 410,959, [Group XXVI], and 549,386 are referred to.