Patent GB-984355-A (GB)
Title: A sink-and-float separating plant
IPC: B03B13/00
Filed: 1961-07-14
Abstract: 984,355. Separating solids. KLOCKNERHUMBOLDT-DEUTZ A.G. July 14, 1961 [July 28, 1960], No. 25601/61. Heading B2H. A method of automatically regulating the specific gravity of the dense medium in a sink- and-float separating plant is characterized in that, when the specific gravity of the working dense medium decreases, dense medium is added and water is withdrawn at the same time, and when the specific gravity of the working dense medium increases, water is added and dense medium is withdrawn at the same time. The system for adjusting the specific gravity of the dense medium consists of a circuit for regulating the specific gravity of a store of heavy densce medium and a circuit for regulating the specific gravity of the dense medium in the sink- and-float plant. The first-mentioned circuit includes a stock tank 10 and a tank 12 between which, when a two-way connection 14 is in the right-hand position as shown in the drawing, the dense medium is circulated by a pump 11 to prevent separation of the solid particles. The specific gravity is regulated by the action of two measuring tubes 22, 23 which are immersed to different depths and the pressure in a differential pressure gauge 24 is amplified and, if the indication is that the specific gravity is too high, operates a relay 27 whereby a valve 28 is operated and admits additional water to the stock tank 10. The two-way connection 14 remains in the right-hand position as shown when a control device 15 is in a condition responsive to the specific gravity of the medium in the sink-and-float plant 1 being above a certain value. This specific gravity is detected in a similar way to that used for the stock tank 10 and the result is passed through an amplifier 25a to the control device 15. The measured value of the specific gravity is also passed to control devices 35, 36. When the specific gravity in the plant 1 falls below the required value the control device 15 changes over the connection 14 and heavy dense medium flows through a pipe 19 into the circuit for regulating the specific gravity of the dense medium in the sink-and-float plant. When the specific gravity in the plant 1 rises above the required value the control device 35 operates a two-way connection 42 to the position where it diverts some of the working dense medium through a pipe 37 into the stock tank 10. At the same time the control device 36 opens a valve 38 through which fresh water passes in to the tank 6 and thus into the circuit for regulating the specific gravity of the dense medium in the sink-and-float plant. The pnuematic control devices 15, 35, 36 are supervised in their operation by electro-magnetic valves 39 in their supply lines, to avoid over-regulation of the specific gravity of the medium, the arrangement being that two switch members 40a, 40b apply voltage pulses to the valve 39, the duration and spacing of which can be continuously adjusted. The apparatus includes a washer 2b for recovering solids from dense medium that overflows from the plant 1, which washer is associated with a clarifier 9 which concentrates the medium that that been diluted by the rinsing water. In the event of failure of the compressed air supply the valve 38 closes and the two-way connections 14, 42 move into the right-hand position as shown.