GB1143640A - - Google Patents

Abstract

1,143,640. Lixiviating apparatus. SOC. FIVES LILLE-CAIL. 21 July, 1966 [3 Aug., 1965], No. 32760/66. Heading B1Q. [Also in Division C6] In a process and apparatus for extracting a substance from highly absorbent comminuted material, a solvent for the substance is circu lated through the comminuted material and the exhausted material is then pressed to express absorbed solution, which expressed solution is purified concentrated and then circulated through the material before the solvent. In extracting sugar from comminuted, highly absorbent material, such as crushed or finely cut-up sugar-cane, the material is fed, from a hopper 24 and past a thickness-controlling member (not shown), to form a layer of a desired thickness on the upper run of the permeable, endless conveying belt 22 travelling from the hopper 24 to the discharge hopper 26 of the diffusion apparatus 10. Water is sprayed, at location 28, on to the layer. The water passes through the layer and extracts sugar from the material. The resulting dilute sugar solution passes through the belt 22 into a collecting vessel 30, from which the solution is sprayed on to the layer at a location 32, which is nearer to the hopper 24 than location 28. The 30-32 collection and circulation is repeated. Substantially exhausted material is discharged, through the hopper 26, on to a conveyer 14, which delivers the exhausted material into a working multi-roller press 12, which expresses absorbed sugar solution. This solution is defecated with lime in a tank 16 and passed into a settling tank 18, from which clarified solution is passed, e.g. decanted, through a steam-heated evaporator 20, e.g. operating under reduced pressure with a very small hydrostatic head, and preferably of the descending type. The concentrated, clarified solution leaving this evaporator is sprayed at location 34 (which is between location 32 and the hopper 24) on to the travelling layer of material, and is collected and passed downwardly through the layer, repeatedly in a manner similar to the 30-32 collection-circulation. It is pointed out that, each solution is sprayed on to the layer at a location where the concentration of sugar in the material is greater than that in the solution. Diffusion juice from the diffuser 10 is concentrated in multipleeffect evaporators (not shown), from the "effects" of which exhaust steam may be used to heat the evaporator 20.