GB773552A - Improvements in decanting liquids containing flocculated material - Google Patents

Abstract

773,552. Purifying liquids. SOC. FRANCAISE DES PRODUITS GELSOL. Oct. 28, 1954 [Nov. 25, 1953], No. 31164/54. Class 46. A method of decanting a dispersion of solids in liquid is characterized by moving through the dispersion solid surfaces, of thin cross-section in relation to their surface extent, at a very low speed in either or both the settling and compression zone of the dispersion, the means plane of the surfaces forming an acute angle with a horizontal plane in the direction of movement. In Fig. 3 a sheet-iron plate 11 is attached to a very slowly-rotating spindle 8 in the lower part of a cylindrical vat 1 ; transverse rectangular apertures 12, Fig. 4, are cut in the plate so that the portions of plate remaining between the apertures are analogous to separate " wings." In the upper part of the vat a grid 10 is attached to the spindle 8. During rotation the decanting particles are impelled downwards. In Fig. 6 four rectangular surfaces 20 to 23, the upper two being gratings and the lower two being solid or apertured as in Fig. 4, are pivoted between vertical arms depending from a frame 26 which is caused to move to and fro on rails along the upper edges of a rectangular vat 29. A rack 32 carrying buffers 33 is moved at each end of the path of motion by contact of the buffers with stops 30, 31, the movement of the rack being communicated through rod or chain mechanism to the surfaces 20 to 23 to rotate them to the position shown or a symmetrically opposite position depending on the direction of motion. The rack may be locked if desired. An example of a curved surface according to the invention is shown in Fig. 8 : it comprises a hollow wing 1a rotatably mounted on a shaft 4 supported by a frame (not shown), rotating about a vertical axis. The angle 6 which a chord 7-8a makes with the horizontal may be taken to represent the mean value of the angle made with the direction of displacement 5 by the tangents to the active surface. The equilibrium position which the wing will tend to assume may be varied by introducing lead shot as ballast into it through a hole which may be hermetically sealed.