Patent GB-515159-A (GB)
Title: Improvements in or relating to the separation of solid materials
IPC: B03B5/62
Filed: 1938-05-25
Abstract: 515,159. Washing granular materials. DU PONT DE NEMOURS & CO., E. I. May 25, 1938, No. 15655. Convention date, May 25, 1937. [Class 82 (ii)] A vessel for carrying out hydraulic or combined hydraulic and flotation classification of minerals or the like has a plurality of liquid supply devices, directed vertically upwards and spaced apart along its bottom, to create vertical upward currents in the vessel, means adjacent the top of the vessel for receiving separately the materials raised by the currents, mechanical means for transporting materials in the vessel transversely with respect to the currents, and means for introducing the materials to be separated into the path of the transporting means. In operation the velocity of the upward current in one or more of the columns mav be reduced to zero so that a preliminary separation may take place in a still column of liquid. The bottom 2 of a vessel 1, which may be cylindrical, Fig. 5, or have upwardly diverging walls, Fig. 24, or upwardly converging walls, is formed with a discharge opening 4 leading to the boot of a conveyer 17 and with a series of circumferentially spaced inlets 3a-3e for upward currents of water, the inlets being separately supplied, e.g., from compartments of a water tank 60 or through valved pipes from a common header, so that the flow through each inlet is adjustable. A series of separating columns is thus formed in the vessel into the first of which, which may be an upward flow or may be substantially quiescent, the material is fed from a shoot 12. The stratifying layers of material are carried through the series of columns of liquid, which may be of successively increasing velocity, by rotors 7 and 8, the former carrying the lower layer and the latter the lighter materials which tend to collect higher in the vessel. The rotors, which are preferably separately driven and may be constructed,in two parts, a fixed part 7a, 8a, and a detachable part 7b, 8b, are formed with inner and outer walls which substantially confine the ascending columns of liquid and are divided into sectors by radial partitions 9, 10. The rotor 8 is open at top and bottom, but the materials settling in the rotor 7 are preferably retained by perforated bottom sector-shaped members 11, each hinged to the bottom edge of a partition 9 and normally kept closed by a cam track 22 which is interrupted at the discharge opening 4 to allow the members 11 to open and dump the material carried by the rotor. The top of the vessel is divided, by means of a depending ring 23 and weirs 63, into sectorshaped spaces 13, Fig. 6, directly above the inlets 3a &c., the weirs, which are preferably adjustable, leading to radial troughs 6a-6f between the spaces 13 and to a surrounding trough 24, closed at its ends 25. The spaces 13 may be divided into compartments by arcuate partitions 93, 94, Fig. 24, and the side weirs 98, 99, 100 of these compartments may be of different heights. The material raised by the ascending currents is thus discharged, either directly or through the troughs 6a &c. into the trough 24 and the material from any one or more of the columns may be separately collected by the use of closure members 27 which may be inserted in the trough 24 between the spaces 13 and discharge devices leading from the trough. As shown, Fig. 6, two discharge troughs 28, 29 are provided, and by placing the member 27 opposite the trough 6d or the trough 6e the material from the column above the inlet 3d may be collected, either with that from the succeeding column or with that from the preceding column. The troughs 28, 29 lead to separate compartments of a vibrating de-watering screen 32, which may be combined with grading screens and which drains into a tank 54 from which the water is pumped to the tank 60: Water supplies are also taken from the tank 60 to the centre of the vessel 1 and to a point above the discharge opening 4. In another form, Fig. 26 (not shown), two discharge openings may be provided in the bottom of the vessel, the second opening for the discharge of the material carried by the rotor 8. A plate is preferably provided between the two rotors adjacent the first opening to prevent discharge of the material carried by the rotor 8 at this point. Means may be provided for introducing air with the water at the inlets 3a &c. and by this means froth flotation may be used to assist the upward-current classification, reagents such as cresol and kerosene being added, e.g., to the water in the tank 54. The specific gravity of the liquid in the vessel may be increased by the addition of finely divided material, e.g., sand, or previously separated fines, the suspension being maintained, for example, by the introduction of air. The washing of coal is described and the washing of sand and the concentration of minerals, e.g., phosphate ore, limestone, and feldspar, referred to.