METHOD AND APPARATUSES FOR SCREENING

Abstract

A leaching tank that can be used in an interstage screening process includes a draft tube with an impeller that extracts slurry or liquid from an interior of a screen basket mounted in the leaching tank. The impeller is driven by a motor, and the speed at which the motor rotates can be selectively varied to vary a flow rate of fluid or slurry being removed from the leaching tank. A position of the input end of the draft tube can be selectively varied within the leaching tank to vary a position within the leaching tank from which fluid or slurry is withdrawn from the leaching tank.

Description

Claims

1. A leaching tank configured for use in an interstage screening process, comprising: a tank;a draft tube configured to be mounted to at least one of the tank and a screen basket located in the tank such that a lower end of the draft tube extends into an interior of the tank, wherein the draft tube also is configured to be connected to an outflow pipe;a rotatable drive shaft that extends through an interior of the draft tube to a location adjacent the lower end of the draft tube; andan impeller mounted to the drive shaft such that when the drive shaft and the impeller are rotated, the impeller causes fluid or slurry to move from the lower end of the draft tube to an upper end of the draft tube.

2. The leaching tank of claim 1, further comprising a motor that is operatively connected to the draft shaft and that is configured to cause the drive shaft to rotate.

3. The leaching tank of claim 2, further comprising a gearing assembly that operatively couples the motor to the drive shaft.

4. The leaching tank of claim 2, wherein a rotational speed of the motor can be selectively varied to selectively vary a flow rate of fluid or slurry through the draft tube.

5. The leaching tank of claim 2, further comprising a controller that is operatively connected to the motor, wherein the controller provides signals to the motor to control a rotational speed of the motor to selectively vary a flow rate of fluid or slurry passing through the draft tube.

6. The leaching tank of claim 1, further comprising a screen basket mounting assembly that is configured to mount a screen basket in an interior of the tank, wherein the draft tube is configured to be mounted to at least one of the tank and a screen basket located in the tank such that when a screen basket is attached to the screen basket mounting assembly, the lower end of the draft tube will be positioned inside the screen basket.

7. The leaching tank of claim 1, further comprising a draft tube mounting assembly that is configured to selectively position the draft tube at differing heights within the tank.

8. The leaching tank of claim 1, further comprising a draft tube mounting assembly that is configured to selectively position the draft tube at different radial positions within the tank with respect to a central longitudinal axis of the tank.

9. The leaching tank of claim 1, wherein at least one of the rotatable drive shaft and the impeller can be selectively re-positioned to different heights within the draft tube.

10. A draft tube assembly for use in a tank configured for use an in interstage screening process, comprising: a draft tube configured to be mounted to at least one of an interstage screening tank and a screen basket located in an interstage screening tank such that a lower end of the draft tube is located inside the interstage screening tank;a rotatable drive shaft that extends through an interior of the draft tube to a location adjacent the lower end of the draft tube; andan impeller mounted to the drive shaft.

11. The draft tube assembly of claim 10, further comprising a motor that is operatively connected to the draft shaft and that is configured to cause the drive shaft and the impeller to rotate.

12. The draft tube assembly of claim 10, further comprising a gearing assembly that operatively couples the motor to the drive shaft.

13. The draft tube assembly of claim 10, wherein a rotational speed of the motor can be selectively varied to selectively vary a flow rate of fluid or slurry through the draft tube.

14. The draft tube assembly of claim 10, further comprising a controller that is operatively connected to the motor, wherein the controller provides signals to the motor to control a rotational speed of the motor to selectively vary a flow rate of fluid or slurry passing through the draft tube.

15. The draft tube assembly of claim 10, further comprising a draft tube mounting assembly that is configured to mount the draft tube to at least one of an interstage screening tank and a screen basket located in an interstage screening tank, wherein the draft tube mounting assembly can selectively position the draft tube at differing heights within an interstage screening tank.

16. The draft tube assembly of claim 10, further comprising a draft tube mounting assembly that is configured to mount the draft tube to at least one of an interstage screening tank and a screen basket located in an interstage screening tank, wherein the draft tube mounting assembly can selectively position the draft tube at different radial positions within the interstage screening tank with respect to a central longitudinal axis of the interstage screening tank.

17. The draft tube assembly of claim 10, wherein the impeller can be selectively re-positioned to differing heights within the draft tube.

18. The draft tube assembly of claim 10, wherein the driveshaft and impeller can be selectively positioned with respect to the draft tube to locate the impeller at differing positions with respect to the lower end of the draft tube.

19. The draft tube assembly of claim 10, wherein a nozzle is located at a lower end of the draft tube.

20. The draft tube assembly of claim 19, wherein the nozzle is removably mounted to the lower the end of the draft tube such that different shaped or sized nozzles can be mounted to the lower end of the draft tube.