Patent GB-766942-A (GB)
Title: Method of and apparatus for separating ore
IPC: B03C7/02
Filed: 1954-11-29
Abstract: 766,942. Electrostatic separators. Mc- CONNELL, D. P. Nov. 29, 1954 [Dec. 4, 1953], No. 34514/54. Class 117 [Also in Group XXX] In an electrostatic separator for granular ore, particles of substantially equal mass but of different ore components are separated as a result of their different "electrolevitation" times, the latter being the time of subjection by an electric field before levitation occurs. Granular material from a conveyer 2 Fig. 2, is fed to a vibrating table 1 having a non-conducting laminated wooden top 4 on a metal frame 3. Charge producing units A, B, C, D, mounted on a frame 31, Fig. 4, comprise a plurality of alternate conducting and non-conducting brushes 20, 21 which are mounted on endless carrier chains 36 for transvese movement ove the table and for brushing contact with non-conducting plates 22, the latter being positioned above the table, and under each unit by hangers 45 secured to frame 31. Separate motors for each unit drive the sprockets 35 on shafts 33 and screws 46 allow adjustment of the platetable separation. The brushes comprise curved steel bases which support convex sponge rubber blocks, Fig. 8 (not shown), composed of two layers separated by a canvas strip, an earthed copper wire screen being provided between the layers in the case of the conducting brushes only. A motor 9, Fig. 2, rotates an eccentric weight 11a, mounted on table-frame 3, to cause vibration of the table, in the form of successive longitudinal thrusts, for advancing material along the table for ultimate discharge at the end 8. A bracket 15 mounted on frame 3 is interposed between a resilient stop 14 and a compression spring 18 both mounted on a rigid member 16, the spring being adjustable for varying the extent of vibration. Leaf springs 5 supporting frame 3 allow an oscillatory motion of the table. In operation, the non- conducting brushes 20 produce charges on plates 22, thus causing particles to be attracted upwards to the plate. The earthed conducting brushes 21 neutralize these charges to cause the particles to drop back again. Transverse movement of the brushes over the plates thus causes some particles to move transversely to the main flow of material for collection in a shoot 55, Fig. 4, having a separate channel for each of units A, B, C, D. Since the " levitation-time " varies with the brush speed. the plate-tube separation and the nature of the particle attracted, the two former quantities may be varied independently for each unit, so that that a specific component of the flowing material is selectively separated by each unit for collection in the appropriate shoot-channel. The plates 22 may be transparent to allow observation of the separation. In a modification, Fig. 10 (not shown), the non- conducting or charge-producing brushes are replaced by rollers; which are rotated, while passing over the plate, by an additional motor-driven endless chain coacting with sprockets mounted on the rolleraxles. In a second modification, Figs. 11- 16, (not shown), the table comprises a number of separate parallel surfaces, fed by a series of hoppers at one end and together spanned by the units A, B, C, D, the transverse distance covered by the separated components before collection being thus reduced. A separate four-channel connecting shoot is provided for each surface.