GB712104A - Improvements in or relating to the separation of solid materials of different specific gravities - Google Patents

Abstract

712,104. Washing granular material. COLLIERY ENGINEERING, Ltd., and NEEDHAM, L. W. June 26, 1952 [May 1, 1951], No. 10193/51. Class 82 (2) Solid materials are separated according to specific gravity by a combination of jig and sink- and-float treatments. The separating medium is recirculated for use in the sink-and-float apparatus, the washery water is recirculated for use in the jig, the discharge of at least one fraction of the sink-and-float apparatus is washed by the washery water to remove adhering medium solids, and the water is then treated to recover these solids for re-use. As shown in the Figure, all the coal is first jigged and then the larger particles of clean coal are screened and passed to the sink-and-float separator, the underflow from the screen (which comprises virtually all the water discharged from the jig) being fed into a canal into which the floated coal is discharged. The mixture of clean coal of all sizes is then classified in the normal manner, the under-flow being thickened and the supernatent liquid returned to the washer circuit. Froth flotation may be used to recover the very fine coal particles. The sink fraction from the float- and-sink separator may be screened, the underflow going to the canal, and the oversize particles either being crushed for return to the beginning of the circuit or discharged. As the shale has been removed in the jig, the sink fraction comprises middlings which may be sprayed off whilst being screened, washery water being used. In a modification (not shown), the coal is initially screened and the small particles (half inch and under) are jigged, whilst only particles over half inch are floated. In this case the shales from both processes are sprayed off and discharged. If desired, the fractions from each separation process may be treated in separate canals, in which case the canal handling the floated fraction drives the wash water from clarified water taken from the exit to the canal down which the washery water flows.