Patent GB-511973-A (GB)
Title: Improvements in or relating to the washing of solid materials in granular or like form
IPC: B03B11/00
Filed: 1938-02-28
Abstract: 511,973. Washing solid materials ; screening-apparatus. IMPERIAL CHEMICAL INDUSTRIES, Ltd. (Du Pont de Nemours & Co., E.I.). Feb. 28, 1938, No. 6297. [Classes 82 (ii) and 117] Superficial contamination is removed from solids by subjecting them to a series of washings, the dirty liquid from the first washings and from the later washings being separately collected and passed respectively to the bottom and to the top of a container. The process is particularly applicable to the removal of heavy separating liquids, e.g. halogenated hydrocarbons, from separated solids, but may also be used to wash naturally occurring minerals, for example to remove sand or clay from phosphate rock. In the form shown the materials are fed by shoots 18 on to washing beds each formed by a number of perforated pans 51 carried by a shaft 35. Three superposed washing beds are provided so that, for example, the float, middlings, and sink from a separating operation may be separately and simultaneously washed. Sprays 28 and 30 above and below the pans are provided for washing the material. Each series of pans 51 is carried by rotation of the shaft 35 over a floor formed by a partition 12 ; adjacent the feed shoot 18 a portion 17 of the floor is sloped to discharge the washings into a channel 19 outside the main wall of the vessel 10, and the remainder of the floor 12 slopes downwardly and inwardly to discharge the later washings through a central funnel 16 into the top of a conical container 11 forming the lower part of the vessel 10. The first washings are conveyed by the channel 19 into the lower part of the container 11, the container being formed with an overflow weir 22 for clean water and a sump 21 with discharge pipes 24, 25 for withdrawal of the heavy liquid &c. Scraper blades 40 and a stirring member 41 attached to the shaft 35 are provided in the lower part of the container 11. Each of the pans is mounted on a stud 48, Fig. 7, the rim 52 of the pan being provided with a stop member 53. engaging a bar 45 to prevent tipping of the pan in one direction, and an angular abutment 54 to allow limited tilting in the other direction. By means of a lever 49 attached to the stud 48 and carrying a stud 50 engaging a cam track 60 the pan is tilted to discharge its contents into a discharge shoot 31 after the washing operation. The pan being then restored to the horizontal position by a cam track 61 which engages the stud 50. The pan is locked in horizontal position by the engagement of a lug 62 on the inner rim 63 of the pan, Fig. 6, with ratchet teeth 67 on a bell crank lever 66, the inner end 68 of which is weighted and engages a pivoted lever 69, the other end of which is connected to a rod 71 pressed upwards by a spring 72 so that a roller 74 co-operates with a cam track 75. The cam track 75 is arranged so that the rod 71 is depressed to unlock the pan just before the stud 50 engages the cam track 60 to tilt the pan, the rod 71 being restored to locking position after the pan has been brought back to horizontal position by the cam track 61. The vessel 10 is provided with water seals for the shaft 35 and for a cover.