Patent GB-969223-A (GB)
Title: Method and apparatus for the recovery of heavy-density liquids from their mixtures with solids
IPC: B03B5/44
Filed: 1961-01-08
Abstract: 969,223. Separating solids. BAKER PERKINS Ltd. Jan. 18, 1961 [Jan. 26, 1960], No. 2027/61. Heading B2H. Relates to processes for the concentration of mineral solids by the sink-and-float method using a heavy-density liquid as a separating medium and consists in a method for the recovery of the separating liquid from the solid matter obtained as a sediment and floated fraction, respectively, by which method the mixture of solid matter and heavy-density liquid is thoroughly mixed with water and then allowed to stratify into an upper aqueous phase and a lower heavy-density liquid phase having a defined interface, the upper aqueous phase being agitated at or near the interface whilst the lower heavy-density liquid phase remains substantially quiet. The solid matter either becomes slurried in the water or collects at the interface between the heavy-density liquid and the water. In the former case the solid matter can be carried off by the water and separated. In the latter case the water layer at the interface is agitated, while being drained of the heavydensity liquid, and the solid matter is thus slurried in the water layer, the resulting slurry then being drawn off. The mixture of solid matter and heavy-density liquid is introduced through a pipe 26 to a mixing vessel 1a, provided with a high-speed rotary agitator 2a, and the water is introduced through a pipe 23. The pulp, when mixed, passes along a conduit 27 to a reservoir tank 28 which is provided with a slow-speed rotary agitator 29 which keeps the pulp in a state of flocculation while it imparts to it a downward movement. The pulp passes from the lower part of the reservoir along a conduit 3a to the separating vessel 4a, into which it is carried upwards by a screw conveyer 35 through an inlet tube 34. The screw 35 is at the lower end of a shaft 7a which also carries a horizontal agitator 5a and rotates at half the speed of the agitator 29. In the upper part of the separating vessel 4a is a water phase and in the lower part is a slurry phase of the heavy-density liquid and solids and the plane of the agitator 5a is located at the interface between the two phases. The agitator produces a localized zone of mixing between the solids of the lower phase and the water so that the solids become suspended and are drawn off through a collecting cone 12a by a pump 11a, passing through conduits 40 and 10a. The heavy-density liquid sinks to the bottom of the vessel 4a and is drawn off through an inverted-U conduit 42, which forms a siphon, for collection and recovery. The pump 11a discharges through a conduit 44 to a cyclone separator 13a, the separated-out solids leaving at 45 and the water being returned to the vessel 4a through a conduit 14a. The rate of withdrawal of the liquids may be controlled by the design of the outflow pipes or siphons, or by the rate of delivery of the pump, so that the interface between the layers remains in the vicinity of the agitator. The conditions in the separating vessel 4a may be observed through an inspection glass 48. Examples are given (i) of the recovery of tetrabromoethane (TBE) from a slurry of TBE with iron ore ; (ii) of the recovery of TBE from a slurry of TBE with chromite ore ; (iii) of the recovery of beryl from a pegmatite ore by a process which includes the step of recovering beryl from a slurry thereof with TBE ; and (iv) of the recovery of bromeform from slurries of bromeform with fluospar and with quartz and calcite.