Patent GB-465841-A (GB)
Title: Improved ore dressing
IPC: F16L37/50
Filed: 1935-12-24
Abstract: 465,841. Washing granular materials; automatic control systems. WUENSCH, C. E. Dec. 24, 1935, No. 35724. Convention date, Nov. 23. [Class 82 (ii)] [Also in Group XXXV] In the gravitational separation of solid particles in a heavy medium comprising a suspension of finely divided solids in liquid, the heavier particles and accompanying medium are pumped substantially continuously out of the lower part of the chamber. The medium is removed from the particles by washing, thickened, and returned to the chamber, a portion of the overflow from the thickening step being returned to the washing step and another portion of the overflow being bled from the circuit. Fine particles of the ore from a bin 1 are washed through a screen 2 by jets 3, 4, 5, beneath which are sand traps 10, 8, 6 respectively. The overflow from the trap 6 is pumped to the jet 4 and that from the trap 8 to the jet 3. The sand from the traps is passed' to a classifier 12 and grinding mill 13 in closed circuit and the ground product from the mill and the overflow from the trap 10 pass to a thickener 11, the thickened sands and the slimes being further treated, e.g. by flotation, if desired. The washed ore passes from the screen 2 to a box 14, to which separating medium is supplied from a classifier 28 and then over a vibrating screen 15, through which excess medium &c. drains away, to the separator 16. The mixture in the separator is agitated by arms 18, 19, 20 on a hollow shaft 17 through which a rod extends having a float 22 on the lower end and a contact 23 on its upper end. When the density or the amount of the material in the lower part of the separator increases, the float 22 rises and the contact 23 closes a circuit which increases the speed of a pump 25 which withdraws the heavier material from the bottom of the separator. The pump 25 may be replaced by an air lift, the volume of air being controlled by the float 22. The material withdrawn is passed to a second separator 41 similar to the separator 16 and having pumping means 42 controlled in a similar way to the pump 25. The tailings from the top of the separator 16, the middlings from the top of the separator 41, and the concentrates from the bottom of the latter vessel pass to separate compartments of a screen 43 divided into three compartments by longitudinal partitions. The first part of the screen is a drainage portion, the medium draining into a hopper 44, and on the rest of the screen the medium is washed out of the material by banks of sprays 73 ,59, 62, and 63. A hopper 56 leading to a sand trap 57 is located beneath the jets 73, a similar hopper 55 and sand trap 60 beneath the jets 59, and a further hopper 54 and sand trap 65 beneath the two banks of sprays 62 and 63. The overflow from the trap 57 is pumped to the sprays 59, that from the trap 60 to the sprays 62, and that from the trap 65 passes to a thickener 64. The sand which collects in the traps is passed to a classifier 66, the medium recovered being sent to the thickener 64. The washed concentrates, washed tailings, andwashedmiddlings pass to the bottom of the screen 43, the tailings being discharged and the middlings sent back to the bin 1 via crushing rolls 92. The overflow from the thickener 64 passes into a froth trap 69 in which oil &c. is removed and colloidal material is removed from the circuit at 70, the dilute clarified medium being utilized to feed the spray bank 63, the amount of fresh water supplied to this spray bank being governed by a float 72 in the froth trap 69. The thickened medium from the thickener 64 is passed to a tank 68 which feeds through a valve 51 into a sump 45 which receives medium from the hopper 44 under the drainage portion of the screen 43. The medium from this sump is pumped to the medium classifier 28 which is connected at the bottom to an elevator casing 29 containing a worm conveyer 30. The medium in the classifier is agitated by arms 32 and a cage-like agitator 33 on a hollow shaft 31 through which extends a rod with a float 35 on its lower end. When the float rises the rod closes contacts 36, 37 which results in the energizing of a valve 39 to open an outlet in the elevator casing. A peripheral launder at the top of the classifier is divided into two compartments by an adjustable partition 96, the inner compartment supplying medium to the separator 16. A hydrometer 47 in the classifier closes contacts 48, 49 on rising which results in an increase in the water supply and a decrease of the supply of medium to the sump 45. A float 52 is also provided in the classifier which, when it falls, increases the supply of medium to the sump 45. The coarse particles removed by the worm 30 are passed to a grinding mill 74 and classifier 75 in closed circuit, the classified product passing to the thickener 64. The separators 16 and 41, or the separator 41 alone, may in certain cases be replaced by jigs, and the classifier 66 may be replaced by the classifier shown in Fig. 2, for the recovery of fine coal. This classifier comprises a conical vessel with a peripheral launder 78, a splash ring 80, and a conical agitator of open formation at the bottom of a hollow shaft 100. A float on the bottom of a rod passing through the hollow shaft controls the rate of withdrawal of the products from the bottom of the classifier and a float 86 governs the supply of additional medium through a valve 85. Fine coal is withdrawn through an outlet 87 by means of a suction pump. Specifications 455,888, 455,889, and 462,200 are referred to.