Patent GB-1050579-A (GB)
IPC: C08B30/04
Abstract: 1,050,579. Starch. DORR-OLIVER Inc. Oct. 10, 1963 [Oct. 15, 1962], No. 39959/63. Heading C3U. In a process of manufacturing starch from grain, the grain is steeped and comminuted, germ is separated from the comminuted grain to form a germ stream and a mill starch stream, the mill starch stream is thickened by subjecting at least a portion of it to hydrocyclonic acid to separate said portion into a light fraction stream and a heavy fraction stream, and the light fraction stream is concentrated by centrifugal action, and combined with the heavy fraction stream for supply to a starch-gluten separation step. The mill starch stream may, before the hydrocyclonic action, be separated into a grit starch stream of relatively high solubles content and a fine fibre starch stream of lower solubles content, the grit starch stream then being hydrocycloned, and at least a portion of the fine fibre starch stream being concentrated and supplied to the starch-gluten separation step. The specific gravity of the feed to this separation step may be controlled by the amount of pre-fibre starch stream included therein. In the starch-gluten separation, the heavy fraction stream, the concentrated light fraction stream and the concentrated fine fibre starch stream are centrifuged to provide an overflow gluten stream and an underflow starch stream, which is then hydrocycloned to provide substantially pure starch underflow. When the fine fibre starch stream is concentrated by separation into a light fraction fine fibre starch stream and a heavy fine fibre starch stream, the light fraction may be supplied to the centrifuging part of the starchgluten separation station, and the heavy fraction supplied to the hydrocyclone part. A portion of light fraction fine fibre starch stream may be used as wash liquid in. the step of centrifugally concentrating the light fraction stream. In one embodiment (Fig. 1, not shown) corn steeped in tank 10 is milled at 20 and separated from germ by flotation at 22. The mill starch stream from 22 is separated from tailings at 28 and passes via mill 32 to station 34 where fine fibre starch (starch milk) is removed from coarse and fine fibre. The grit starch from 28 passes to a mill stream thickening station consisting of centrifuges 40, 42 and hydrocyclones 38 wherein the grit starch is separated into a light fraction overflow and a heavy fraction underflow. The light fraction passes via 41 to centrifuges 40, the underflow from which is combined with the heavy fraction for delivery to the starch-gluten separator. Overflow 50 (mainly water) is directed to the steeping station. A part of the underflow from 34, i.e. the fine fibre starch stream, passes via 45 to centrifuge 42, the underflow from which (47) is combined with underflow streams 46 and 48 to provide combined starch-gluten stream 52. The high sp. gr. of this stream is reduced by combining it with the remaining part of the fine fibre starch stream 54 so that a stream 56 is fed to the starch-gluten separation station consisting of centrifuges 58 and hydrocyclones 60. The overflow 59 from centrifuge 42 is combined with that from centrifuges 40 to form a waste stream 57. Wash water may be supplied to the centrifuges via 61.