Patent GB-682234-A (GB)
Title: Process and apparatus for the sink and float separation of solid materials, using a heavy liquid
IPC: B03B5/36
Filed: 1947-09-10
Abstract: 682,234. Sink and float separation. VOGEL, W. Sept. 10, 1947 [Sept. 11, 1946], No. 24863/47. Class 82(ii) [Also in Group XXX] Materials to be separated by the sink and float process are fed into a continuous, non-turbulent stream of the heavy liquid carried on a conveyer moving horizontally, or in a direction inclined downwardly at a small angle to the horizontal, the velocity of the stream being equal to at least onehalf of the square root of double the product of the depth of the liquid and gravity, the liquid being fed over the whole width and depth of the stream at the same velocity as the conveyer and being discharged freely over the whole width and depth of the stream, the discharge stream being divided horizontally into layers carrying materials of different densities. The materials to be separated are preferably fed with the same velocity as the stream and the conveyer, in a layer the depth of which is equal to the size of the largest particles of the materials. The stream of heavy liquid may be formed of a number of superimposed layers of liquids of different densities and the total depth of the stream may be 2.5-4 times the size of the largest particles to be separated. The conveyer 17, Fig. 1, is formed by an endless rubber belt of rectangular cross-section, the side walls being corrugated, pleated or made of cellular rubber to facilitate stretching when passing over the pulleys 18, 19; idlers 20, 21 support the working and return portions respectively. Heavy liquid is fed on to the conveyer through the duct 23 and materials, to be separated through the conduit 24, submersion being ensured by the rotor 25: the end cf the conduit 24 may be vibrated. A vane 27 projects into the discharge stream and floats and sinks are removed on plates 28. 29 respectively. In a modification, Figs. 3 and 6, the conveyer is in the form of an endless belt 31, protuberances 34 on the back thereof engaging with grooves in the pulleys 32, 33 and idlers 36 and flanges 43 being formed near the edges of the belt. The sides of the launder are formed by driven belts 39 engaging with the flanges 43, lateral deflection of which is prevented by fixed strips 44. In a further modification, the bottom belt and side belts form moving linings of a fixed launder. In another form, the launder is formed by two angle section belts, the horizontal lugs of which overlap, a layer of cellular rubber being interposed between them. In a still further form, Fig. 11, for use when perfection of separation is less important, an endless belt 2 travels over the bottom of a stationary launder 1, the belt being of rubber with metal plates vulcanized thereto. The liquid stream is composed of layers S, S<SP>1</SP> of different densities and screen-like separator vanes 10, 11 cut into each of the layers to separate their products. The launder and conveyer may be adjustable about the axis 3. The liquid streams are recirculated via reservoirs 13. 15 and pumps 14, 16 respectively. Travelling rubber belts may also be employed as covers or a stream of air may be caused to flow over the surface to avoid atmospheric friction. The Specification as open to inspection under Sect. 91, refers also to the use of a sloping fixed launder without moving: belts. This subject-matter does not appear in the Specification as accepted.