GB570845A - Improvements relating to methods of washing coal and to coal-washing jigs - Google Patents

Abstract

570,845. Wet separating. NORTON, R. M., and NORTON, G. B. May 11, 1943, No. 7485. [Class 82 (ii)] In the separation of coal from refuse by stratifying the material in accordance with the specific gravity of its constituents in water which rises and falls pulsatingly, the specific gravity at which the separation takes place is varied in dependence upon the ratio of clear coal to reject, increasing as the rate increases and vice versa. The-separation is effected by separately discharging the parts of the stratified bed above and below a given specific gravity which is increased as the depth of the reject part of the bed decreases and vice versa. The rate of discharge may be controlled by a float and mechanical means may be provided for increasing the specific gravity as set out above. In the form of the apparatus shown in Figs. 1, 5 and 6, the float 21 is carried by a parallellinkage mechanism consisting of horizontal arms 22, 23 and vertical arms 24, and the arm 22 has a rearward extension 28 between which there is a rigid frame composed of transverse members 29 and runners 30 on which run two weights in the form of grooved rollers 31 both mounted in ball-bearings 32 on a rod 33, the end of which lie between springs 34, 35, the inner ends of which are looped round the rod 33 and the outer ends anchored in the forked ends of tensioning screws 36, 37 independently adjustable in brackets 38, 39 fixed to the arms 28. When the float 21 falls and the arms 28 move out of the horizontal, the weights will move downwards allowing the springs 34 to contract and the springs 35 to extend so that the torque exerted by the weights will change. Members 40 forming part of the frame with the arm 38, form stops for the .weights to prevent the float moving up and down as the water pulsates ; a dashpot 44 such as is described in Specification 565,016 is used. The flow of the reject is controlled by a gate 4 pivotally connected by a rod 5 to a lever 6, one end of which carries a weight 7 and is pivoted at 8 to a bracket 9. The other end of the lever 6 is connected to a piston-rod 10 connected to a piston 11 working in a cylinder 12 and the gate is lowered when compressed air is introduced into the cylinder by a pipe 13, the flow of air being controlled by a relay valve 14 which includes a slide member having an arm lying between screws in the forked end of a calliper arm which is rigidly fixed to a rod which is rocked about its axes in bearings or brackets by the float. 21. In another form, a balance weight instead of the rollers 33, is mounted on an arm fixed to the rod 19. In a third form, instead of the rollers 33, a cylindrical counterbalance weight is supported on a curved platform carried by the arm 28 and in a fourth form, two vessels containing liquid are connected at their bottoms by a narrow-bore pipe and mounted in the arms 24 instead of the weight, and if desired a byepass pipe may be mounted in the bore to act as a dashpot. In a fifth form, two electromagnets are mounted to exert equal and opposite attraction on an armature formed of a soft iron weight carried by the end of the arm 24.