Patent EA-000326-B1 (EA)
Title: Method of separating intermixed materials of different specific gravity
IPC: B04B11/02
Filed: 1996-07-11
Abstract: 1. A method of separating intermixed particulate materials of different specific gravity in a slurry comprising:  providing a centrifuge bow) having a peripheral wall and an open mouth;  rotating the bowl about a longitudinal axis so as to rotate the peripheral wall around the axis;  feeding the materials to the bowl so as to pass over the peripheral wall and causing heavier particles to tend to collect on the peripheral wall while lighter particles tend to escape in the slurry over the open mouth;  defining in the materials collected on the peripheral wall an inner surface of the materials over which the fed materials pass at which the heavier particles collect;  defining around the peripheral surface at least one annular recess spaced outwardly of the inner surface;  providing in the recess a plurality of angularly spaced discharge ports at an outer surface of the recess, each for allowing materials collecting at the recess to discharge outwardly from the peripheral wall;  collecting the outwardly discharged materials;  and injecting fluidising liquid into the annular recess through a series of angularly spaced injection ports; characterized in the step of:  providing for each discharge port a respective one of a plurality of deflection guide bodies each supported within the recess radially inwardly of the respective discharge port;  arranging the injection ports and the deflection guide bodies to allow flow of the injection fluid around the annular recess; and  shaping and arranging the deflection guide bodies relative to the respective discharge ports such that material is drawn from the inner surface at the recess over an area which forms a substantial part of the inner surface at the recess. 2. The method according to Claim 1 wherein each body is substantially circular in a cross-section at right angles to an imaginary line from the respective discharge port to the axis of the bowl. 3. The method according to Claim 1 or 2 wherein each body is mounted in the recess on a rod member having rod portions extending upwardly and downwardly respectively of the body such that the rod portions bridge across the recess generally parallel to the axis of the bowl. 4. The method according to Claim 1,2 or 3 including:  providing a first and a second annular recess at axially spaced areas along the bowl, each having a plurality of said angularly spaced discharge ports at an outer surface of the respective recess for allowing materials collecting on the inner surface at the recess to discharge outwardly from the peripheral wall for collection;  providing for each of the discharge ports of the first and second recesses valve means for controlling discharge of the materials from the respective recess;  controlling each valve in a series of pulses so as to open and close the valve repeatedly to discharge the material in sequential portions;  controlling the valve means of the first recess separately from those of the second recess respectively so as to provide for each of said first and second recesses different discharge characteristics to provide different concentrations of the heavier particles relative to the lighter particles in the materials collected;  and collecting the outwardly discharged materials from the second recess separately from the materials from the first recess. 5. A method of separating intermixed particulate materials of different specific gravity in a slurry comprising: providing a centrifuge bowl having a peripheral wall and an open mouth; rotating the bowl about a longitudinal axis so as to rotate the peripheral wall around the axis; feeding the materials to the bowl so as to pass over the peripheral wall and causing heavier particles to collect on the peripheral wall while lighter particles in the slurry escape over the open mouth; providing on the peripheral surface a first and a second annular collection area with the second axially spaced downstream of the first; providing in the first and second areas a plurality of angularly spaced discharge ports, each for allowing materials collecting at the area to discharge outwardly from the peripheral wall; providing for each of the discharge ports of the first and second areas valve means for controlling discharge of the materials from the respective area, controlling each valve in a series of pulses so as to open and dose the valve repeatedly to discharge the material in sequential portions;  and collecting the outwardly discharged materials; characterized in the steps of: separately controlling the valve means of the first and second areas respectively so as to provide for each of said first and second areas different discharge characteristics to provide different concentrations of the heavier particles relative to lighter particles in the materials collected; and collecting the outwardly discharged materials from the second area separately from the materials from the first area. 6. The method according to Claim 4 or 5 wherein the valves of the first area are commonly controlled for simultaneous operation and the valves of the second area are commonly controlled for simultaneous operation. 7. The method according to Claim 4, 5 or 6 wherein the valves of the first and second areas are controlled such that a total period that the valves of the second area are open is greater than that of the first so as to discharge a greater volume of material from the second area. 8. The method according to Claim 4, 5, 6 or 7 wherein the bowl has a support shaft, wherein the valves of the first area are controlled by a first fluid supply circuit having a portion thereof extending along the shaft, wherein the valves of the second area are controlled by a second fluid supply circuit having a portion thereof extending along the shaft, and wherein the first and second fluid supply circuits include coaxially arranged first and second duct portions extending along the shaft, each duct portion being supplied with fluid from a separate first and second stationary swivel coupling mounted on the shaft. 9. The method according to Claim 8 wherein the swivel couplings are arranged at axial ly spaced positions. 10. The method according to Claim 8 or 9 wherein fluidising liquid is supplied to the bowl through the peripheral wall, including supplying the fluidising liquid through a duct portion of the shaft coaxial with said first and second duct portions of the fluid circuits.