GB822856A - Process for separating magnetisable particles from contaminating non-magnetisable particles, present in suspension - Google Patents

Abstract

822,856. Filters. STAMICARBON N. V. Aug. 2, 1957 [Aug. 4, 1956], No. 24612/57. Class 46. [Also in Group II] Raw coal is separ ated, by means of a magnetite suspension in a separator 1, intc washed coal and shale. The coal fraction with some sepa rating suspension leaves at B and passes across a screen 2, the suspension dripping through and being collected in a tank 3 for return to the separator by a pump 4. The fraction is then passed across a screen 5 where it is cleaned by water sprays 6, 7 before being discharged at D. The shale, which leaves the separator 1 at C, undergoes similar treatment and is discharged at E ; the screens 2, 5 may be of the vibrating type with a mesh of 1mm. The dilute suspension passing through the screens 5 is collected in a tank 8 and supplied by means of a pump 9 to a curved screen 10 consisting of spaced bars having gaps of 0À5 mm. between them. 90% of the magnetite contained in the dilute suspension is collected in a tank 11 beneath the screen 10 and is then passed to a magnetic separator 12 from which a concentrated magnetic suspension is pumped to the collecting tank 3 via a demagnetising coil 14. This suspension together with that from the screens 2 is then pumped to the separator 1. Alternatively, the suspension from magnetic separator 12 may be pumped direct to the separator 1. Water may be added to the separator 1 at G. In the separator 12 also, a dilute non-magnetic fraction which contains only non-magnetisable particles smaller than 0À25 mm. is separated out and supplied to a tank 15 which also receives the overflow fraction from the screen 10 consisting mainly of the non- magnetisable particles larger than the magnetite. The fractions collected in the tank 15 are pumped into a hydrocyclone thickener 17 from which the clarified overflow is led to the sprays 6 and the apex discharge is treated in a second magnetic separator 18. The separated magnetic fraction is returned to the tank 8 and the non-magnetic fraction leaves the system at F. In place of the screen 10, a cyclone separator or a group thereof may be used. Specifications 791,520, 791,857, 791,858 and 791,859 are referred to.