Apparatus for cement blending capable of forming a thick slurry

1. An apparatus for mixing and discharging a slurry of water and cement comprising:

a pressure vessel adapted to contain slurry and including a first inlet connected to a source of pressurized driving fluid and a first outlet for discharge of the slurry upon pressurization of the vessel by the driving fluid;

an agitating mechanism disposed to mix the slurry within the pressurized vessel and including an impeller disposed within the vessel such that rotation of the impeller causes the slurry initially to flow downwardly from the impeller to be redirected outwardly and upwardly in a circulatory mixing action; and

a vibrating mechanism for vibrating the vessel to facilitate mixing of the slurry and discharge of the slurry from the vessel by the driving fluid.

2. An apparatus as claimed in claim 1 wherein the vessel has substantially vertical side walls and a lower section disposed in the bottom of the vessel below the impeller and tapering inwardly to the first outlet.

3. An apparatus as claimed in claim 2 wherein the impeller includes a substantially vertical drive shaft disposed centrally in the vessel and at least one mixing element supported by the drive shaft.

4. An apparatus as claimed in claim 3 including an externally mounted motor and gear box assembly driving the drive shaft.

5. An apparatus as claimed in claim 4 including a stuffing box assembly to prevent ingress of slurry into the gear box assembly.

6. An apparatus as claimed in claim 3 wherein the impeller includes two mixing elements supported by the drive shaft and each comprising a series of mixing blades.

7. An apparatus as claimed in claim 3 including a scraper connected to the drive shaft and adapted to remove cement slurry from an inside surface of the vessel.

8. An apparatus as claimed in claim 7 wherein the scraper is positioned to scrape the inside surface near the top of the intended slurry volume.

9. An apparatus as claimed in claim 1 wherein the vessel is suspended from load cells to isolate vibration.

10. An apparatus as claimed in claim 1 wherein the vessel further comprises second and third inlets respectively adapted to introduce water and cement into the pressure vessel.

11. An apparatus as claimed in claim 10 including a control valve associated with each of the second and third inlets.

12. An apparatus as claimed in claim 1 wherein the vessel comprises a second outlet adapted to vent air displaced from the pressure vessel to atmosphere when the vessel is filled with water and cement.

13. An apparatus as claimed in claim 12 including a filter associated with the second outlet.

14. An apparatus as claimed in claim 12 including a control valve associated with each of the first and second outlets for selectively opening and closing the outlets.

15. An apparatus as claimed in claim 1 including a trailer adapted to support the pressure vessel for road transportation.

16. An apparatus as claimed in claim 15 including two pressure vessels mounted on the trailer.

17. An apparatus as claimed in claim 15 including a diesel generator and an air compressor for the vessel mounted on the trailer.

18. An apparatus as claimed in claim 1 including a valve for opening and closing the first outlet and a controller which controls the valve to open the first outlet when the vessel is pressurized by the driving fluid to above atmospheric pressure.

19. An apparatus as claimed in claim 18 wherein the controller controls the valve to open the first outlet when the vessel is pressurized by the driving fluid to between two and five bar.

20. An apparatus as claimed in claim 18 including a valve for opening and closing the first inlet, wherein the controller controls the valve for the first inlet to open the first inlet to admit the driving fluid while the agitating mechanism is mixing slurry within the vessel.

21. An apparatus as claimed in claim 18 wherein the controller controls the vibrating mechanism to vibrate the vessel while the agitating mechanism is mixing slurry within the vessel.

22. An apparatus as claimed in claim 1 wherein the vibrating mechanism vibrates the entire vessel.

23. An apparatus as claimed in claim 22 wherein the vibrating mechanism contacts a side wall of the pressure vessel.