Patent GB-408367-A (GB)
Title: Improvements in or relating to apparatus for washing coal and other granular materials
IPC: B03B5/18
Filed: 1932-11-09
Abstract: 408,367. Washing granular materials. EBBW VALE STEEL IRON & COAL CO., Ltd., Ebbw Vale, and HARVEY, A. H., 5, Badminton Grove, Ebbw Vale, Monmouthshire. Nov. 9, 1932, No. 31672. [Class 82 (ii).] Granular material, e.g. coal slurry, to be washed is passed over a series of superposed inclined tables each of which is supplied with water or other liquid to carry the lighter particles in one direction while the heavier particles are moved in the other direction by endless conveying means travelling successively over the tables and comprising parallel chains and riffle bars arranged between the chains. The particles to be rewashed which are usually the lighter particles fall through or between the riffle bars at one end of the table and are passed to the succeeding table while the other particles are discharged. A framework 1 carries a desliming screen 6, four inclined tables 2, 3, 4 and 5, the inclination being preferably adjustable, a dewatering screen 9 below the table 5, and a conduit 15 with branch pipes 16 connected to spraying pipes 17 for feeding water on to the screen 6 and the tables. An endless conveyer 10 comprising two or more parallel chains carrying riffle bars passes in succession over the screen 9, the tables 5-2 and the screen 6. The riffle bars 12 may be arranged in two series at different levels, the two series being either in staggered relationship, Fig. 6, or oppositely disposed, Fig. 7, in which case the bars may be mounted on plates 13 pivoted to the chain links at 13<a>, the pivotal movement being controlled by the contact of pins 14 with slotted end portions 13<b> of the plates. Alternatively a single set of pivoted riffle bars may be used, Fig. 8, which automatically swing into operative position when the conveyer moves from one table to the next. Coal slurry is fed on to the screen 6, which may be inclined, through a pipe 7 connected to a number of troughs 8, Fig. 5, and water from the spray pipes 17 washes the slimes through into a sump leading to waste or to clarification and retirculating means. The sludge is moved by the riffle bars 12 and falls into a trough 6<a> leading to the uppermost table 2. The lighter particles of coal, agitated and lifted by the swirling motion produced by the riffle bars, are washed down the table 2 by the water from the spray pipe 17 and fall into a trough 2<a> leading to the table 3 and having a dewatering screen 31, Fig. 2, which is kept clean by water sprays from a pipe 36 which is axially oscillated by link and lever mechanism 37. The heavier particles carried up the table 2 pass by a trough 2<b> to a sump 20 containing a worm conveyer 21, the trough 2b having a dewatering screen 33 kept clean by an oscillating spray pipe 36. Similar washing occurs on each of the tables 3, 4 and 5, the coal from table 5 passing to the dewatering screen 9 on which it may be sprayed if desired. The heavier material from table 2 is passed from the sump 20 to a discharge pipe 24, that from tables 4 and 5 which may be of fairly low ash content is passed from the sumps associated with these tables to discharge pipes 25 and 26 having a common outlet 27, while the sump associated with table 3 can, by means of a flap valve 30, be put into communication either with a discharge pipe 28 leading to waste or with a pipe 29 entering the outlet 27 of pipes 25 and 26. Any number of tables may be provided and the ash content of the washed product may be varied by altering the speed of the conveyer, the quantity of water supplied or both of these factors.