Colloidal mixing method for slurries

Abstract

Colloidal mixing of cementitious material into a liquid such as water to form a grout slurry for pumping to a location for use includes a mixing tank and a colloidal mixing mill which grinds and pumps the mixed material with the material being repeatedly circulated between the mill and the tank. The colloidal mixing mill includes a housing defining a generally cylindrical chamber containing a rotor shaped to define a clearance of the order of 3 mm between the front and rear wall of the housing and the rotor with holes from a dished front face of the rotor to the rear face to carry the mixed materials to the clearance where a shearing action takes place to shear the particles in the mixed materials prior to exit through the outlet.

Claims

1. A method for colloidal mixing of a particulate material containing particles into a liquid to form a slurry comprising: supplying the particulate material and the liquid to a mixing tank for mixing to form a mixed material; providing a colloidal mixing mill which grinds and pumps the mixed material; and communicating the mixed material containing the particulate material and the liquid from an outlet of the mixing tank to an inlet of the colloidal mixing mill; the colloidal mixing mill acting to pump the mixed material back to the to the mixing tank such that the mixed material is repeatedly circulated between the colloidal mixing mill and the mixing tank; the colloidal mixing mill comprising; a housing defining a chamber with a generally cylindrical outer wall surrounding an axis of the chamber, a front wall and a rear wall; an inlet arranged in the front wall of the chamber and an outlet in the outer wall; a rotor mounted in the chamber for rotation about the axis of the chamber having a front face of the rotor at the front wall of the chamber and a rear face of the rotor at the rear wall of the housing; the rotor comprising a hub at the axis of the chamber and a plurality of angularly spaced lobes each extending from the hub outwardly of the axis to an outer tip adjacent the outer wall so that rotation of the hub acts so as to carry the mixed material from the inlet to the outlet and to pump the mixed material through the outlet; the rotor and the housing being shaped to define a clearance between the rear wall of the housing and the rear face of the rotor; and providing a plurality of holes at angularly spaced positions around the axis through the rotor from the front face of the rotor to the rear face of the rotor to carry the mixed material to the clearance at the rear face of the rotor where a shearing action takes place to shear the particles in the mixed material prior to exit through the outlet.

2. The method according to claim 1 wherein a further clearance is defined between the front wall of the chamber and the front face of the rotor.

3. The method according to claim 1 wherein said holes are inclined rearwardly from an inlet end of said holes at said front face of the rotor to said rear face and are inclined outwardly from the axis.

4. The method according to claim 1 wherein the front face of the rotor at the inlet forms a concave dish.

5. The method according to claim 1 wherein the rotor runs at speed from 1200 to 2200rpm.

6. The method according to claim 1 wherein the clearance between the lobes of the rotor and the outer wall of the chamber is less than 5mm.

7. The method according to claim 1 wherein the clearance between the lobes of the rotor and the outer wall of the chamber is of the order of 3mm.

8. The method according to claim 1 wherein the colloidal mixing mill acts as a pump to transfer the mixed material to a required location.

9. The method according to claim 1 wherein: each of the lobes has a rear face adjacent the rear wall of the chamber; each of the lobes has a leading face with a side edge of the leading face at the rear wall of the chamber and a trailing face with a side edge of the leading face at the rear wall of the chamber; the rotor and the housing being shaped to define said clearance between the rear wall and the rear face of the lobes; and the shearing action takes place between the rear wall of the chamber and said side edge of said leading face of the lobes of the rotor.

10. The method according to claim 9 wherein the holes exit respective ones of the rear faces of the lobes.

11. A method for colloidal mixing of a particulate material into a liquid to form a slurry comprising: supplying the particulate material containing particles and the liquid to a mixing tank for mixing to form a mixed material; providing a colloidal mixing mill which grinds and pumps the mixed material; and communicating the mixed material containing the particulate material and the liquid from an outlet of the mixing tank to an inlet of the colloidal mixing mill; the colloidal mixing mill acting to pump the mixed material back to the to the mixing tank such that the mixed material is repeatedly circulated between the colloidal mixing mill and the mixing tank; the colloidal mixing mill comprising; a housing defining a chamber with a generally cylindrical outer wall surrounding an axis of the chamber, a front wall and a rear wall; an inlet arranged in the front wall of the chamber and an outlet in the outer wall; a rotor mounted in the chamber for rotation about the axis of the chamber having a front face of the rotor at the front wall of the chamber and a rear face of the rotor at the rear wall of the housing; the rotor comprising a hub at the axis of the chamber and a plurality of angularly spaced lobes each extending from the hub outwardly of the axis to an outer tip adjacent the outer wall so that rotation of the hub acts so as to carry the mixed material from the inlet to the outlet and to pump the mixed material through the outlet; the rotor and the housing being shaped to define a clearance between the rear wall of the housing and the rear face of the rotor; and providing at least one hole through the rotor from the front face of the rotor to the rear face of the rotor to carry the mixed material to the clearance at the rear face of the rotor where a shearing action takes place to shear the particles in the mixed material prior to exit through the outlet; wherein said at least one hole is inclined rearwardly from an inlet end of said at least one hole at said front face of the rotor to said rear face and is inclined outwardly from the axis.

12. The method according to claim 11 wherein said at least one hole comprises a plurality of holes where the holes each exit respective ones of rear faces of the lobes at the rear face of the rotor.

13. A method for colloidal mixing of a particulate material containing particles into a liquid to form a slurry comprising: supplying the particulate material and the liquid to a mixing tank for mixing to form a mixed material; providing a colloidal mixing mill which grinds and pumps the mixed material; and communicating the mixed material containing the particulate material and the liquid from an outlet of the mixing tank to an inlet of the colloidal mixing mill; the colloidal mixing mill acting to pump the mixed material back to the to the mixing tank such that the mixed material is repeatedly circulated between the colloidal mixing mill and the mixing tank; the colloidal mixing mill comprising; a housing defining a chamber with a generally cylindrical outer wall surrounding an axis of the chamber, a front wall and a rear wall; an inlet arranged in the front wall of the chamber and an outlet in the outer wall; a rotor mounted in the chamber for rotation about the axis of the chamber having a front face of the rotor at the front wall of the chamber and a rear face of the rotor at the rear wall of the housing; the rotor comprising a hub at the axis of the chamber and a plurality of angularly spaced lobes each extending from the hub outwardly of the axis to an outer tip adjacent the outer wall so that rotation of the hub acts so as to carry the mixed material from the inlet to the outlet and to pump the mixed material through the outlet; the rotor and the housing being shaped to define a clearance between the rear wall of the housing and the rear face of the rotor; and providing at least one hole through the rotor from the front face of the rotor to the rear face of the rotor to carry the mixed material to the clearance at the rear face of the rotor where a shearing action takes place to shear the particles in the mixed material prior to exit through the outlet; wherein the front face of the rotor at the inlet forms a concave dish.

14. The method according to claim 13 wherein said at least one hole is inclined rearwardly from an inlet end of said at least one hole at said front face of the rotor to said rear face and is inclined outwardly from the axis.

15. The method according to claim 13 wherein said at least one hole comprises a plurality of holes where the holes each exit respective ones of rear faces of the lobes at the rear face of the rotor.

16. A method for colloidal mixing of a particulate material containing particles into a liquid to form a slurry comprising: supplying the particulate material and the liquid to a mixing tank for mixing to form a mixed material; providing a colloidal mixing mill which grinds and pumps the mixed material; and communicating the mixed material containing the particulate material and the liquid from an outlet of the mixing tank to an inlet of the colloidal mixing mill; the colloidal mixing mill acting to pump the mixed material back to the to the mixing tank such that the mixed material is repeatedly circulated between the colloidal mixing mill and the mixing tank; the colloidal mixing mill comprising; a housing defining a chamber with a generally cylindrical outer wall surrounding an axis of the chamber, a front wall and a rear wall; an inlet arranged in the front wall of the chamber and an outlet in the outer wall; a rotor mounted in the chamber for rotation about the axis of the chamber having a front face of the rotor at the front wall of the chamber and a rear face of the rotor at the rear wall of the housing; the rotor comprising a hub at the axis of the chamber and a plurality of angularly spaced lobes each extending from the hub outwardly of the axis to an outer tip adjacent the outer wall so that rotation of the hub acts so as to carry the mixed material from the inlet to the outlet and to pump the mixed material through the outlet; each of the lobes having a rear face adjacent the rear wall of the chamber; each of the lobes having a leading face with a side edge of the leading face at the rear wall of the chamber and a trailing face with a side edge of the leading face at the rear wall of the chamber; the rotor and the housing being shaped to define a clearance between the rear wall of the housing and the rear face of the rotor including the rear face of the lobes; and providing at least one hole through the rotor from the front face of the rotor to the rear face of the rotor to carry the mixed material to the clearance at the rear face of the rotor where a shearing action takes place to shear the particles in the mixed material prior to exit through the outlet; wherein the shearing action takes place between the rear wall of the chamber and said side edge of said leading face of the lobes of the rotor.

17. The method according to claim 16 wherein said at least one hole is inclined rearwardly from an inlet end of said at least one hole at said front face of the rotor to said rear face and is inclined outwardly from the axis.

18. The method according to claim 16 wherein said at least one hole comprises a plurality of holes where the holes each exit respective ones of the rear faces of the lobes at the rear face of the rotor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) One embodiment of the invention will now be described in conjunction with the accompanying drawings in which:

(2) FIG. 1 is a first isometric view of a mixing apparatus for carrying out a method according to the present invention.

(3) FIG. 2 is a second isometric view of a mixing apparatus for carrying out a method according to the present invention.

(4) FIG. 3 is a schematic illustration of the method of the FIGS. 1 and 2.

(5) FIG. 4 is a cross-sectional view along the lines 4-4 of FIG. 1.

(6) FIG. 5 is a cross-sectional view along the lines 5-5 of FIG. 1.

(7) FIG. 6 is a cross-sectional view along the lines 6-6 of FIG. 1.

(8) FIGS. 7 and 8 are isometric views of the rotor alone from the apparatus of FIG. 1

(9) In the drawings like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION

(10) The apparatus shown in the figures is used in a method for colloidal mixing of a particulate material into a liquid to form a slurry.

(11) The apparatus includes a mixing tank 10 for mixing to form a mixed material which includes in a top wall 14 a water inlet pipe 11 and an opening 12 with a cover 13 for feeding particulate material. The tank has a cylindrical peripheral wall 15 with two sets of tangential inlet jets 16 and 17 where each includes three jets stacked along the height of the wall 15. A bottom discharge 18 in a bottom wall of the tank is arranged to supply the mixed materials from the bottom of the tank through a pipe 19 to a colloidal mixing mill 20 which grinds and pumps the mixed material.

(12) The colloidal mixing mill 20 acts to pump the mixed material back to the to the mixing tank 10 through a return pipe and the jets 16, 17 such that the material is repeatedly circulated between the colloidal mixing mill 20 and the mixing tank 10.

(13) As shown in FIG. 3, the mixing mill 20 has tangential outlet 23. The outlet 23 feeds pipe 21 through control valves V3 & V4. It also feeds an outlet discharge pipe 24 controlled by a valve V1 which can direct the material when fully mixed to an end use location at the end of the pipe 24. The outlet 23 also can supply the mixed material from the mill 20 back to the tank through a central feed pipe 25 through the top of the tank and along a center axis of the tank 10.

(14) The whole system sits on a transport base frame 26 which also carries a motor 27 which drives the mill 20 through a belt drive 28 and a shaft 29 carried on bearings 30.

(15) The colloidal mixing mill 20 includes a housing 31 formed by a rear portion 32, through which the shaft 29 passes, and a front portion 33 clamped together by bolts 34. The housing defines a chamber 35 with a generally cylindrical outer wall 36 surrounding an axis 37 of the chamber. An inlet 38 is arranged at one end of the chamber in a front wall 39. A tangential outlet 23 is provided in the cylindrical outer wall so that the mill 20 can act as a conventional pump where the material entering the inlet 38 is carried around the cylindrical wall by a rotor 40 carried on the shaft 29.

(16) The rotor 40 mounted in the chamber 35 for rotation about the axis 37 of the chamber so as to carry the mixed materials from the inlet 38 to the outlet 23 so as to pump the mixed materials through the outlet.

(17) The rotor 40 and the housing 31 are shaped to define clearances 41 and 41A between a flat stationary rear wall 42 of the housing and a flat rotating rear wall of the rotor 40 and between a flat stationary front wall 42A of the housing and a flat rotating front wall of the rotor 40 wherein both clearances a shearing action takes place to shear the particles in the mixed materials prior to exit through the outlet 23.

(18) Thus the clearances are defined between the rear and front walls 42 of the chamber opposite the inlet and the adjacent rotating rear wall of the rotor including a hub portion 44 and four lobes 45 of the rotor, both of which have a surface lying in the same flat rear plane of the rotor. The lobes 45 are shaped with leading edge 46 and trailing edge 47 which act to carry the mixed materials from the inlet outwardly to the outer wall to a tip 48 of the lobe adjacent the generally cylindrical outer wall of the housing to eject the material through the outlet extending outwardly from the hub. The shearing action primarily takes place between the side edges of the leading surface 46 at the front and rear walls as the lobes rotate.

(19) The rotor also includes four transfer holes 49 each aligned with a respective lobe and each extending through the hub from an inlet end 50 of the hole at the front face 52 of the rotor to receive the mixed materials therefrom to an outlet end 51 of the hole 49 at the rear wall 42 of the rotor. The holes 49 are inclined rearwardly and outwardly from the inlet end 50 thereof to the rear end 51 so that the rotation of the rotor tends to drive the material through the hole 49 to the rear wall of the rotor.

(20) The front face of the rotor facing the inlet forms a concave dish 51 within which the inlet ends 50 of the holes 49 are located. The outlet ends are spaced outwardly from the hub aligned with the concave dish so as to be located in the rear face of the respective lobe.

(21) Thus the concave dish 51 in the front face of the rotor is recessed from the plane containing the front face 52 of the housing so that the mixed materials entering the inlet 38 can enter into this recessed dish area and can then pass either through the holes to the rear wall of the housing or around the outside edge of the dished area to the front face of the housing. In both areas at the front and rear the shearing action takes place between the lobes and the walls of the housing.

(22) After refilling of water in the mixer the water is then recirculated through the mixer and grout lines returning into the mixer and spraying the inside and cleaning residue left over from the last batch. This dirty water is then used in the next batch. This process also reduces the amount of wastewater that is used in the process of cleaning the system.

(23) Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense.