Patent GB-669215-A (GB)
Title: Means for separating extraneous substances from, or for grading or sorting, granular, powdered or like materials
IPC: B07B9/00
Filed: 1949-11-28
Abstract: 669,215. Pneumatic separating. VAHEY, L., HENRY, C., and PHILLIPS, J. V. Nov. 3, 1950 [Nov. 28, 1949 ; May 26, 1950], Nos. 30411/49 and 13275/50. Class 117 In a pneumatic separator, granular or powdered material is fed into a vertical duct a on to a perforated screen extending partly across the duct from one side wall thereof below an outlet w which leads to a settling chamber y and from which an inclined baffle p extends to a short distance from the screen, and air is caused to flow through the material as it is fed on to the screen j to divert the lighter particles into the settling chamber y or on to the baffle, p; and to flow through the screen j and between the screen j and the baffle p to divert any remaining light material into the chamber y, means k being provided to deliver from the screen any material remaining thereon. As shown in Fig. 1, the material is fed via a rotary valve c and deflectors d, e, on to a pivoted inclined deflecting plate f which feeds the material in a curtain on to a downwardly inclined, slidably adjustable perforated feed screen i which extends from the duct side wall opposite the outlet w and overlies the free end of screen j to provide an air gap 20 therebetween, the screen j being inclined upwardly from its adjacent duct wall. The lower portion of screen j underlies a pivoted perforated baffle p and is of upright or inverted V form, or laterally inclined, to allow residual material to gravitate to a duct or ducts k leading to a transparent observation box o and thence to a discharge duct m. The air stream is induced by a fan 2 in the settling chamber y and enters the lower end of duct a through an adjustable inlet s, a pivoted deflector u directing the air upwardly towards screens i, j. The settling chamber y has conical lower walls leading to a rotary discharge valve 5, the wall remote from the adjustable chamber inlet w having baffles 6 to cause cascading of the material into valve 5. An adjustable air inlet 21 is provided just above valve 5 to provide a final aspiration of the lighter material settling in the chamber y, Fig. 2 shows an arrangement wherein the material is fed on to an inclined perforated screen 9 mounted in front of a second adjustable air inlet 7 and having its lower end pivoted to a slidably adjustable imperforate baffle 11 replacing the screen i of Fig. 1. In a modification of the Fig. 2 arrangement, the baffle 11 is fixed and screen 9 is stepped from screen j by a perforated spacing member. Various modifications of the Fig. 1 arrangement are described wherein screen i is integral with and stepped from screen j or is replaced either by curved imperforate feed plates separate from or integrally stepped from screen j, or by a conveyer band or fluted feed rollers. The second Provisional Specification describes an arrangement wherein a single curved perforated screen extends across the duct, one half having a horizontal baffle therebelow and air inlets being provided above and below the baffle. Alternatively, the upper half of the curved screen is formed imperforate and the horizontal baffle and upper air inlet omitted.