Patent GB-501658-A (GB)
Title: Improvement in process of and apparatus for separating minerals from gangue
IPC: B03B5/36
Filed: 1937-08-31
Abstract: 501,658. Wet - separating. DU PONT DE NEMOURS & CO., E. I. Aug. 31, 1937, No. 23779. Convention date, Aug. 31, 1936. [Class 82 (ii)] To classify a mixture of mineral-containing solids of differ. ent specific gravities, the mixture is introduced into a horizontal stream of a separating liquid of intermediate specific gravity, and after allowing sufficient distance for the pure heavy particles to sink the stream is divided so that part of the middlings are diverted upwards to join the float and part downwards to join the sink. The separating liquid is preferably immiscible with water, a list of suitable liquids, mainly halogenated hydrocarbons, being given, and it may be covered with a layer of water into which the solids are introduced. The flow of the separating liquid may be produced by the flights of conveyers used for removing the float and sink products. The apparatus shown (Fig. 1) comprises a tank 3 with cover-members dipping into water seals so that the tank is vapour-tight. Separating liquid is introduced through a valve 359 to a chamber 358 which communicates with the tank by apertures 360 and has an open topped cylinder which leads back to the liquid storage tank and controls the level of liquid in the tank. A layer of water is introduced into the tank at 375 and an overflow 362 is provided. The water may be introduced continuously or intermittently. The material is introduced by a shoot 328, divided by partitions 329, which can bo attached to either side of the tank. Means arc provided for withdrawing vapours from the shoot 328. The material passes into a hopper-shaped chamber, the lightest particles being removed by a conveyer 343 which carries them along the surface layer of the separating liquid and up over a screen 339 to a shoot 340. The heaviest particles fall into the track of the conveyer 317 and are carried up the conveyer pan 321, which terminates in a screen 323 spaced from the wall of the tank, to a discharge shoot 322. The middlings which are carried along by the flow of separating liquid produced by the convoyers are divided by a wedge formed by hinged members 335 and 337, the former being hinged to the lower end of the pan of the upper conveyer 343. Various means are descrihed for altering the position of the apex of the wedge to the relative proportions of middlings directed to the float and sink. The liquid draining through the screening portions of the conveyer pans passes back between the hoppershaped chamber and the tank to the entry end and recirculates through apertures 331 in the entry end wall of the chamber. The apparatus is particularly suitable for separating coal from its impurities but a list of other minerals which may be treated is given. An apparatus for testing the proportions of heavy and light particles in the separated portions comprises a trough 75, Fig. 2a, divided into a series of compartments for liquids of varying specific gravities. Each compartment is provided with a perforated tray 752 hinged to one side of the trough. The material is introduced into the first compartment, the floating material is removed by a perforated shovel 760, which is run along guide bars 759, and fed into the next compartment, the sink in each compartment being removed by swinging the tray 752 about its hinge to discharge the material on to a table 765 at the side of the trough. Specifications 501,655 and 501,657 are referred to.