GB758178A - Process for separating mixtures of particles differing in size and specific gravity, into fractions according to specific gravity - Google Patents

Abstract

758,178. Separating granular materials. STAMICARBON N.V. Nov. 16, 1954 [Nov. 21, 1953], No. 33195/54. Class 82(2). Mixtures of particles of differing sizes and specific gravities are separated according to specific gravity by first sizing them on a screen 1, using a magnetic suspension of specific gravity such that the screen underflow can be treated directly in a hydrocyclone 8 or a sink- and-float separator to give light fines 9 and heavy fines 11. The magnetic portion of these fractions is recovered by the separators 12, 10 and returned to the initial screening step, the gravity being corrected by water added at 16. Each fraction is again subjected to magnetic separation 37, 23, the residual magnetic material passing to a thickener 21. The purified fractions are thus dewatered in cyclones 41, 27 and filters 44, 30. The liquid from the filters is also passed to the thickener. The coarse particles pass to a mixing tank 5 and, together with added medium, pass to an inclined or horizontal hydrocyclone 52. The light fraction is screened at 53, the heavies at 59. The drained-off medium together with the thickened product from 21, passes back to the mixing tank 5. The washed-off medium is added to the first stage magnetic separators 12, 10. Additional magnetite may be added at 74 and demagnetised at 75. The thickener overflow f may be further heated e.g. by froth flotation to recover the wanted fractions and the froth then returned to the thickener 21. The tailings from the froth flotation may be flocculated. The diagram is of a coal washery. Specifications 662,794 and 726,510 are referred to.