Patent GB-428614-A (GB)
Title: Improvements in or relating to concentrating tables for washing coal and the like
IPC: B03B5/04
Filed: 1933-11-15
Abstract: 428,614. Washing granular materials. NEEDHAM, L. W., 99, Middle Park Road, Selly Oak, Birmingham. Nov. 15, 1933, Nos. 31803/33 and 36055/34. [Class 82 (ii)] To separate solid materials of different specific gravities a thick bed of the materials is agitated and liquid is distributed over the bed in such restricted quantities that the bed is composed predominantly of solid materials and free-flowing currents are absent. The upper and lower strata of the bed are separately discharged and some or all of the material discharged may be reconcentrated, for example on a riffled concentrating table. In the form shown the concentration is effected in an elongated box d which replaces part of the surface of an ordinary riffled concentrating table b, the box and the table being mounted on a framework u supported on flexible inclined legs and vibrated by a rotating unbalanced pulley v<1>, a bumping effect being produced by contact of a cross-bar y, which may be provided with a pad z of leather &c., with a stop member x. The box d has upstanding sides of sufficient height to retain a thick bed of material, one of the sides d<2> being of less height than the others to provide a spillage edge f for the lighter particles. The material, mixed with just sufficient water to wet the particles, is fed to the box at one end by a hopper e spaced from the spillage edge f, and at the other end of the box is a gate g, which may be constituted by a fixed or adjustable dam or by a swinging flap, under which the heavier particles pass. Water in restricted quantities is distributed over the bed by spray pipes r, and deflecting members 3, the lower edges of which are above the level of the spillage edge, are provided to aid the discharge of the lighter materials over the spillage edge. The floor of the box, which may be covered with linoleum, is preferably slightly inclined downwards towards the discharge end and a sloping platform 7, Figs. 1 and 3, may be provided at the feed end to prevent packing of the heavy particles. The box preferably decreases in width towards the discharge end as shown, and beyond the gate g a parallelsided portion D may be attached having a spillage edge o lower than that of the box d, and a spray pipe s. Beyond the portion D, or directly attached to the box d where the portion D is omitted, is provided an upwardly inclined discharge shoot l for the heavy particles. A gate k is provided between the portion D and the shoot l, and the shoot is provided with a spray pipe t and may be hinged at n, Fig. 4, and formed with a riffled surface and with a short spillage edge p near the gate k. When coal is being treated, the clean coal discharges from the box on to an unriffled portion a<3> of the table b, the middlings discharge on to the riffled portion of the table, either directly or by means of a launder 4 or a plurality of launders, and are further concentrated on the table in the usual way. The stone passing out of the shoot l may be discharged directly or may pass on to the end portion of the concentrating table. In an alternative form of box, Fig. 7, both sides of the box form spillage edges f for the lighter particles and the feed hopper is centrally located at one end. Some of the lighter particles are discharged directly into shoots, while the middlings &c. are further concentrated on riffled surfaces provided on both sides of the box. The box and concentrating table may be separately vibrated, or the box may be used without any further concentrating device, or small riffled surfaces may be directly attached to one or both sides of the box.