Patent GB-142246-A (GB)
Title: Improvements in the grading or concentration of ores and the like
IPC: B07B7/01
Filed: 1919-03-14
Abstract: 142,246. Gasohe, F. G. March 14, 1919. Powder blowers and the like.-Relates to the treatment of ore to separate the metal bearing portions from the gangue by projecting the crushed ore in a stream of air into a resisting atmosphere so that the particles fall at distances depending on their density and size, and consists in surrounding the stream of air and particles of ore at an initial discharge by an atmosphere which prevents lateral dispersion of the stream whilst allowing linear expansion of this. The ore is crushed in a mill 6 and is delivered therefrom alternately to two tanks 9 having spouts 11 leading to mixing-heads 12 which discharge, through mixing-chambers 13 and an elbow 14, into a single gun 15. Compressed air is supplied from a comprssed 16 to branch pipes 22, 22<11>, 23, 17<11>, and the gun 15 discharges the mixture of air and crushed ore at a high velocity over a closedin floor 3 provided with hoppers 18, 19, 20 for collecting the various grades of ore, the air in the shed resisting the flight of the particles and causing thento fall at various distances from the gun. The ore is forced from the tanks 9 alternately by air from the pipe 22" and flows through the spout 11 into the head 12, the flow being assisted by air from the pipe 22. The head 12 comprises two parts 12', 12<11>, the part 12<1> having therein a tube 24, with a valve seating 25 at its lower end adapted to receive a valve 27, and a conical surface 26. The part 12" has therein a cavity 31, in continuation of a cavity 30 in the part 13, and an adjustable conical ring 32 movable to adjust the width of the conical passage 33, to which air is supplied from an annular cavity 34 in communication with the pipe 23. Secured to the elbow 14 is a combining- tube 35 the outer, and smaller, end of which communicates, through a tube 36 preferably having a flexible part 36', with a second combining tube 37 the tip of which is formed by a nozzle 38. Attached to the tube 37 is a head 39 containing a central cavity 40 and an annular cavity 41; the head is closed by a plate 42 so arranged as to leave a narrow opening 43 whereby air may flow from the cavity 41 to the central cavity 40. At the centre of the plate and in axial alinement with, and spaced from, the nozzle 38 is a plug 44 having a conical nozzle 40 formed therein with a slight flare 45<1> at the inner end thereof. In operation, the mixture of crushed ore and air after leaving the head 12 flows along the elbow 14 into the passage 35 where, owing to the contraction of area, the velocity of the mixture is augmented; it then passes through the tube 36 to the tube 37, where the velocity is further augmented, leaving this tube at a high velocity but with reduced pressure. Air is supplied from the branch part 17", through a reducing-valve 17<a> to the cavity 41 and emerges from this to the central cavity 40, the valve 17<a> being so set that the pressure of the air, as it enters the cavity 40, is equal to the static pressure of the stream emerging from the nozzle 38; lateral dispersion of the stream is thus prevented, whilst further linear expansion is allowed. The stream of ore and air, together with the air from the cavity 40, then emerges from the nozzle 45 and expands linearly, down to atmospheric pressure thus again receiving further augmentation of velocity; the air from the cavity forms a lubricating-envelope around the stream and reduces abrasion of the nozzle by the particles. In place of air, other compressed gas or superheated steam may be employed; materials other than ore may be treated by the apparatus. Specification 142,389 is referred to.