GB750535A - Improvements in controlling the feed of material to crushers - Google Patents

Abstract

750,535. Controlling feed to grinding mills. SMIDTH & CO., AKTIESELSKAB, F. L. Feb. 4, 1954, No. 3381/54. Class 59. [Also in Groups XXX and XXXV] A device responsive to the discharge rate of material from a crusher 1 onto a discharge conveyer 4 is adapted to reduce the speed of or stop a conveyer 2 feeding material to the crusher when the discharge rate rises above a predetermined value and vice versa. In one form, Fig. 1, two feelers 5, 5<SP>1</SP>, are placed over the discharge conveyer 4, contacts of associated switches 8, 8<SP>1</SP> being connected in series to complete a circuit, when the average height of material on the conveyer rises above a predetermined value, to a relay 11 controlling the speed of the feed conveyer 2, whereby the speed of the latter is reduced. Feelers 5, 5<SP>1</SP> also close other contacts of the switch 8 when the average height falls below a predetermined minimum. These contacts are connected in series with a switch 10 operated by a feeler 9 over the feed conveyer when the level on the latter rises above normal owing to a blockage in the crusher or its feed hopper, so that under these conditions a further circuit is completed to relay 11 to switch off the motor 3 of belt 2 and to actuate an alarm 12. Crusher 1 is of the hammer mill type. Instead of the two feelers 5, 5<SP>1</SP> and switches 8, 8<SP>1</SP>, one feeler and switch may be used by making relay 11 operate only after a delay. In a second form (not shown) flap 9 is omitted and crusher 1 is a jaw crusher for partly crushing the material which then passes from the belt 4 to a hammer mill crusher for further crushing the material. In a further form, Fig. 3, the discharge conveyer 4 is suspended from a weighing machine which operates a relay 17 controlling a further relay 18 either directly or through the switch 10 according to whether the weight is more or less than a predetermined value.