Centrifugal flotation apparatus and method

Abstract

The apparatus includes a powered bowl assembly having a tubular shaft journalled within a base of the apparatus. A pressurized air flow is discharged into slurry in the bowl assembly via a circular array of bubble generators. An impellor discharges the slurry outwardly against an upwardly inclined annular surface of the bowl assembly to cause the slurry to merge upwardly with the streams to promote flotation. Slurry within the bowl assembly forms a vortex with particle flotation forming a froth layer inwardly of a slurry vortex. The froth exits the bowl assembly upwardly past a barrier partially closing the bowl assembly. Heavier gangue particles exit via an outlet about the bowl assembly periphery. A collector shroud is partitioned to receive the froth and the heavier waste material. A modified form of the apparatus includes an independently powered bowl assembly and impellor.

I claim: 
     
       1. A centrifugal apparatus for separating by flotation mineral or metallic particles from a slurry, said apparatus comprising, a base,   impellor means for dispersing the slurry about the impellor axis,   a bowl assembly about said impellor means and into which the slurry is discharged by the impellor means, drive means for said bowl assembly, bubble generating means discharging streams of bubbles, conduit means in communication with a source of air to provide an air flow to bubble generating means, an inclined surface outwardly of the impellor means and against which slurry impinges prior to mergence with the bubble streams generated by the bubble generating means, a first bowl outlet, a second bowl outlet offset from said first outlet, and   collector means disposed about said bowl assembly and defining chambers for the separate collection of material from the first and second outlets.   
     
     
       2. The apparatus claimed in claim 1 wherein said impellor means is coupled to and driven by said bowl assembly. 
     
     
       3. The apparatus claimed in claim 1 wherein said inclined surface is continuous. 
     
     
       4. The apparatus claimed in claim 3 wherein said inclined surface is of curved section. 
     
     
       5. The apparatus claimed in claim 1 wherein said bubble generating means include ceramic inserts inset in said bowl assembly outwardly adjacent said inclined surface. 
     
     
       6. The apparatus claimed in claim 5 wherein said inserts are in a circular array. 
     
     
       7. The apparatus claimed in claim 1 wherein said bowl assembly has outwardly convergent surfaces terminating at said first outlet. 
     
     
       8. The apparatus claimed in claim 7 wherein said bowl assembly has an annular barrier, said second outlet embodied in a barrier rim past which slurry froth moves. 
     
     
       9. The apparatus claimed in claim 7 wherein said outwardly convergent surfaces terminate in opposed flanges, spacers interposed between said flanges, means removably securing said spacers in place to permit spacer replacement to vary the size of said first bowl outlet. 
     
     
       10. The centrifugal apparatus claimed in claim 1 wherein said collector means is in the form of a shroud disposed about the bowl assembly. 
     
     
       11. The centrifugal apparatus claimed in claim 10 wherein said second bowl outlet is defined by an annular barrier plate partially closing the bowl assembly. .Iadd. 
     
     
       12.  A centrifugal apparatus for separating particles from a slurry by flotation, said apparatus comprising, a base,   impeller means for dispersing a slurry about an impeller axis,   a bowl assembly about said impeller means and into which the slurry is discharged by the impeller means, the bowl assembly including a first bowl outlet and a second bowl outlet offset from said first outlet,   drive means for said bowl assembly,   gaseous bubble generating means for discharging gaseous bubble streams and merging the discharged gaseous bubble streams into the slurry dispersed by the impeller means,   conduit means in communication with a source of gas for providing a gaseous flow to the gaseous bubble generating means, and   collector means disposed about said bowl assembly and defining chambers for separately collecting material from the first and second outlets. .Iaddend. .Iadd.13. The apparatus claimed in claim 12 wherein said impeller means is coupled to and driven by said bowl assembly. .Iaddend. .Iadd.14. The apparatus claimed in claim 12, further comprising:   
     
     
       separate drive means for said impeller means. .Iaddend. .Iadd.15.  The apparatus claimed in claim 12 wherein said bubble generating means is circumferentially arranged about the bowl assembly. .Iaddend. .Iadd.16. The apparatus claimed in claim 12 wherein said bubble generating means includes porous aerators in said bowl assembly. .Iaddend. .Iadd.17. The apparatus claimed in claim 12 wherein said aerators are in a circular array. .Iaddend. .Iadd.18. The apparatus claimed in claim 12 wherein said bowl assembly has outwardly convergent surfaces terminating at said first outlet. .Iaddend. .Iadd.19. The apparatus claimed in claim 18 wherein said bowl assembly has an annular barrier, said second outlet embodied in a barrier rim past which slurry froth moves. .Iaddend. .Iadd.20. The apparatus claimed in claim 18 wherein said outwardly convergent surfaces terminate in opposed flanges, spacers interposed between said flanges, and   means removably securing said spacers in place to permit spacer replacement   
     
     
        to vary the size of said first bowl outlet. .Iaddend. .Iadd.21.  The centrifugal apparatus claimed in claim 12 wherein said collector means is in the form of a shroud disposed about the bowl assembly. .Iaddend. .Iadd.22. The centrifugal apparatus claimed in claim 12 wherein said second bowl outlet is defined by an annular barrier plate partially closing the bowl assembly. .Iaddend. .Iadd.23. A method for separating particles from a slurry by flotation comprising the following steps: dispersing a slurry about an impeller axis,   discharging gaseous bubble streams about the impeller axis and merging the discharged gaseous bubble streams into the dispersed slurry,   rotating the slurry containing the gaseous bubble streams about the impeller axis to subject it to centrifugal force, and   separating the resulting froth from the remainder of the slurry. .Iaddend. .Iadd.24. The method claimed in claim 23, including the following additional step:   angularly deflecting the dispersed slurry as the gaseous bubble streams are merged into the slurry. .Iaddend.