GB1432722A - Installations for the sorting of solid particles - Google Patents

Abstract

1432722 Pneumatic classifiers F1VES-CAIL BABCOCK 23 Jan 1974 [29 Jan 1973] 03176/ 74 Headings B2H and B2P An installation for sorting solid particles comprises a centrifugal-action, pneumatic selector 10, Fig. 1, which separates the particles into a fine fraction, which is discharged by a current of air, and at least one coarse fraction which is collected at the bottom of the selector, and a washing box 38 for removing fine particles entrained in the coarse particles, the box being connected to the coarse fraction outlet of the selector by way of an air lock 34 (36) and comprising a series of superposed baffles 58 inclined to the vertical, Fig. 2, the coarse particles to be washed of fine particles being brought to the upper baffle from which they fall onto the lower baffles forming a series of cascades, and the washing air being admitted into the bottom of the box and flowing upwards to pass through the curtains of particles 'between the baffles thereby entraining the fine particles towards a discharge outlet at the top of the box. The selector 10 consists of outer and inner part-cylindrical, part-conical shells 12, 14 closed at the upper end by a cover and defining an inner chamber 18 and an annular outer chamber 16. Particulate material to be sorted is introduced by an injector 29 into an air admission conduit 22 which is connected to the delivery side of a fan 26 and to the bottom of the chamber 16. As the air enters the chamber 16 it expands and gives up the coarsest particles which fall to the bottom of the chamber, the rest of the particles being carried with the air which passes through bladed apertures 20 at the top of the shell 14 and is thereby subjected to rotational movement in the chamber 18. As a result the coarse particles are separated out by centrifugal force and fall to the bottom of the chamber 18 and the fine particles are discharged with the air through a conduit 24 leading to a cyclone 28 which has a clean air discharge conduit connected to the fan 26 and to a fan 40 which supplies air through a conduit 42 to the washing box 38. Excess air coming from uncontrolled air intakes is dedusted through a filter 47 and discharged to the atmosphere by a fan 46. The coarse particles are delivered from the chambers 16 and 18 via conduits 30 and 32 and air locks 34 and 36 to the washing box 38. Washing air containing fine particles is discharged through a conduit 44 which is connected via regulating valves 50 and 52 respectively to the selector 10 and to the cyclone 28. In a modification, Fig. 3 (not shown), the washing box is divided by an axial partition into two symmetrical parts each equipped with baffles and forming two generally parallel passages through which the coarse particles and the washing air pass in counter-current to each other.