Patent GB-349108-A (GB)
Title: Improvements in method of and apparatus for concentrating mineral
IPC: B03D1/02
Filed: 1930-01-20
Abstract: 349,108. Concentrating ores. DAMAN, A. C., 1419, 17th Street, Denver, Colorado, U.S.A. Jan. 20, 1930, No. 1918. Convention date, June 3, 1929. [Class 82 (ii).] In concentrating ores the ore is ground to a medium mesh so that only a portion of the ore is freed from gangue and the crushed ore is then subjected to flotation, the tailings from the flotation apparatus being treated to separate a middling product which is returned for regrinding and further flotation treatment. The ore is crushed in a pulverizer 11 and screened in a rotating screen 12 of “-inch mesh, the ore passing through being conveyed first to a conditioner 16, containing an agitator 17, in which additional water and frothing reagents may be added and then through a flotation box 14 containing a series of flotation cells. The tailings from the last cell pass to a concentrating table 75 which separates them into clean tailings, a middling product and mineral concentrate, the middling product being returned to the pulverizer 11 for regrinding after which it is subjected to flotation with or without freshly crushed ore. At the bottom of each flotation cell an agitator 20, comprising a circular disc 23 with spaced radial upper blades 22 formed with tapering openings 24 and shallow radial lower blades 25, is mounted on a rotating shaft 21 driven by an electric motor. To deflect the pulp upwardly the disc 23 may be curved upwardly at its outer edge or a cast-iron bowl 30 may be fitted in the bottom of the cell. Extending entirely over the agitator is a cover 31, made in two sections 38, 39 bolted together along abutting flanges 40, and supported by webs 35, preferably cast integrally with the cover, extending to the corners of the cell. The cover is provided with holes 32 through which heavy sands and mineral may return for further agitation. The pulp reaches the agitator through the cover by a passage 29 provided with an air trap 48 and the froth concentrate from the launders of any cell may, if desired, be returned for retreatment through openings 37, leading to passages 36 with air traps 49. Grids 41, 42 extend across the cell above the cover 31. Air or gas, preferably under pressure, is introduced through a valved pipe 47 to a tube 43 surrounding the agitator shaft which carries vanes 51 to assist in forcing the air into the pulp. Additional flotation reagents may also be introduced into the tube 43 and additional air or gas may be introduced through a connection 50 into the bottom of the cell. The froth rises over submerged baffles 56, Fig. 5, and passes over front and back lips 52 into launders. Double launders are provided, a launder 53 in which the froth is normallv collected and a launder 54, which may be covered when not required, to which the froth is admitted if it is to be returned for retreatment. Pipes 55 connect the launders 54 with the apertures 37 and concentrate return pipes 36. A middling product which collects below the froth zone is returned to the agitator through a rotatable L-shaped tube 58 opening into the tube 43. The pulp, directed up a passage 72 formed by a plate 73, flows over a weir 62 formed by an adjustable weir plate 63 cooperating with the wall 64, which is cut low at 71, and passes into a compartment 65 formed between the wall 64 and the front wall 66 of the succeeding cell and communicating with the pulp inlet 29 of that cell. Any particles which are not driven up the channel 72 may pass to the space 65 through an opening 74 in the wall 64.