GB340027A - Improvements in or relating to the classification of materials by elutriation - Google Patents

Abstract

340,027. Classifying powdered materials &c. ANDREWS, L., 11, Southampton Row, London. Sept. 19, 1929, No. 28454. [Classes 23 and 82 (ii).] Classification of sand, powdered material &c. is effected by subjecting liquid containing the material to the combined action of centrifugal force and of gravity in a classifier having free outlets at top and bottom, the rate of discharge being controlled by siphonic or suction action at the top outlet. Liquid to be treated is introduced tangentially at e into the classifier between the top and bottom outlets, the heavier particles striking the walls a and falling down sloping walls a<1> to an outlet d. Liquid carrying finer material in suspension passes into an annular space h between cones f, g in the upper portion of the classifier, any intermediates passing through the space h and being discharged to join the heavies at the bottom of the classifier while the fines pass through perforations f <2> in the cone f and are discharged at b, the upward flow being produced and controlled by a siphon pipe c, the effective length of which may be varied by varying the height of liquid in a chamber u surrounding its lower end. The fluidity of the heavy particles and consequently their rate of discharge are controlled by a supply of liquid, e.g. water, through a pipe o to a vessel k from which it is discharged circumferentially through an outlet k<1> between the vessel k and an adjustable plate k<2>. This flow of liquid is normally directed upwardly owing to the siphonic action but in the event of a considerable accumulation of heavy particles in the space m it is diverted downwards and the rate of discharge is increased. In a modification, Fig. 2, a second siphon pipe 3 is provided, each of the pipes c, 3 having an air inlet valve 4, 5 to control the rate of discharge. An auxiliary siphon pipe 6, connected to the main pipe c, carries a barometric device 7 by which the air valves 4, 5 are automatically controlled and the density of the discharge through the main pipe c is rendered practically constant.