GB603218A - Method of ore dressing - Google Patents

Abstract

603,218. Wet-separating. McNEILL, H. L. June 10, 1943, No. 9360. Convention date, June 20, 1942. [Class 82(ii)] In the dressing of ore in which the ore is ground in a closed circuit with a classification stage to produce a final product of flotation size, the product discharging from the grinding stage is subjected to a hydraulic classification so that substantially all the product of finely ground flotation size is directly eliminated and the oversize product left is treated for the recovery of its free mineral constituents prior to the recirculation of that product through the grinding circuit. The oversize product is separated into two grades, one containing the free mineral content and the other the middlings, the latter being reground and the free mineral so separated removed. The pulp passing directly from the grinding stage is subjected to a hydraulic classification preferably in apparatus described in Specification 603,215, to produce three separate products, the first substantially of the product resulting from flow across the classification tank and which becomes the finished product, the second a mixture of coarse free mineral and larger middlings and finally a mixture of fine middlings and coarser gangue, the middlings product being again ground and free mineral content removed in each case. The finished product may be subjected to a secondary treatment such as froth flotation, to remove the mineral content, the second grade to a jigging or gravity separation to recover the free mineral and the third grade to froth flotation or screening to concentrate the finer middlings which are then reground. The material from the ball mill 4 is passed across a tank 1 provided with a spigot department 1a and an overflow department 1b the coarse free mineral and larger middlings passing off to the jigging apparatus 2, the middlings being returned to the mill 4 and the mineral content to the smelter 8. The fine material overflowing from the classifier 1b is fed into a flotation circuit 5, the finished concentrates passing to a thickener 6 and to a filtering apparatus 7 before being fed to the smelter 8, the fine middlings or tailings passing to waste. The fine middlings and coarse gangue are subjected to froth flotation at 3, the fine middlings being returned to the ball mill 4, and the coarse gangue to waste.