Lump conditioner for a mixer

Abstract

A mixer having i) a vessel defining a mixing chamber surrounded by boundary walls for receiving a mixture containing lumps therein, ii) a plurality of mixing blades, and iii) a driving mechanism supporting the mixing blades in the mixing chamber for mixing motion relative to the vessel so as to mix the mixture within the mixing chamber of the vessel, further includes at least one lump conditioning blade. The lump conditioning blade is supported by the driving mechanism such that the lump conditioning blade is movable in a working direction along a respective one of the boundary walls with a working edge of the blade being maintained at a prescribed space from the boundary wall which is effective to reduce a lump size of the lumps in the mixture as the mixture passes between the working edge of the lump conditioning blade and the boundary wall.

Claims

1. A mixer for mixing a mixture containing lumps of prescribed diameter therein, the mixer comprising: a vessel defining a mixing chamber therein surrounded by boundary walls for receiving the mixture containing the lumps therein; a plurality of mixing blades; and a driving mechanism supporting the mixing blades in the mixing chamber for mixing motion relative to the vessel so as to mix the mixture within the mixing chamber of the vessel; the mixing blades including: at least one lump conditioning blade having a rigid body terminating at a working edge along an outer side of the rigid body and which is supported by the driving mechanism so as to be movable in a working direction of rotation along a respective one of the boundary walls; said at least one lump conditioning blade having a main portion occupying a majority of a leading face of the lump conditioning blade that is oriented transversely to said one of the boundary walls; the working edge of said at least one lump conditioning blade being oriented substantially parallel to the respective boundary wall and at an angle relative to the working direction of rotation between 60 and 90 degrees; the working edge of said at least one lump conditioning blade being supported at a prescribed space from the boundary wall which is smaller than the prescribed diameter of the lumps so as to be effective to smear the lumps in the mixture against said one of the boundary walls and to reduce a lump size of the lumps in the mixture as the mixture passes between the working edge of the lump conditioning blade and the boundary wall; at least one primary blade having a rigid blade body terminating at a working edge along an outer side of the rigid body and which is supported by the driving mechanism so as to be movable in said working direction of rotation along said one of the boundary walls along the same path as said at least one lump conditioning blade in a trailing relationship relative to said at least one lump conditioning blade; the working edge of said at least one primary blade being directly adjacent to said one of the boundary walls so as to (i) be in closer proximity to said one of the boundary walls than the working edge of said at least one lump conditioning blade and (ii) be arranged to scrape the mixture from said one of the boundary walls that was smeared against said one of the boundary walls by said at least one lump conditioning blade.

2. The mixer according to claim 1 wherein the boundary walls of the vessel include a general cylindrical portion and wherein the driving mechanism comprises at least one horizontal shaft supporting the mixing blades thereon for rotation about a horizontal mixing axis.

3. The mixer according to claim 1 wherein the boundary walls of the vessel include a pair of generally cylindrical portions and wherein the driving mechanism comprises a pair of horizontal shafts associated with the pair of cylindrical portions respectively upon which the mixing blades are supported for rotation relative to the boundary walls.

4. The mixer according to claim 1 wherein the working edge of said at least one lump conditioning blade is discontinuous along a length thereof.

5. The mixer according to claim 1 wherein the working edge of said at least one lump conditioning blade is serrated.

6. The mixer according to claim 1 wherein the working edge of said at least one primary blade is disposed at an angle relative to the working direction of rotation thereof which is less than an angle of the working edge relative to the working direction of rotation of said at least one lump conditioning blade.

7. The mixer according to claim 1 wherein a leading face of the blade body of said at least one primary blade is disposed at an angle relative to the working direction of rotation thereof which is less than an angle of the main portion of the leading face of the rigid body of said at least one lump conditioning blade.

8. The mixer according to claim 1 wherein the working edge of said at least one lump conditioning blade is oriented near perpendicular to the working direction of rotation.

9. The mixer according to claim 1 wherein the leading face of the rigid body of said at least one lump conditioning blade includes an outer end portion locating the working edge thereon which is disposed radially outwardly relative to the main portion and which is sloped relative to a plane of the main portion, the working edge being supported spaced rearwardly in a trailing relationship in the working direction of rotation relative to the plane of the main portion of the leading face of the rigid body.

10. The mixer according to claim 9 wherein the main portion of the rigid body of said at least one lump conditioning blade is substantially perpendicular to the respective boundary wall.

11. The mixer according to claim 9 wherein the main portion of the rigid body of said at least one lump conditioning blade is near perpendicular to the working direction of rotation.

12. A mixer in combination with a mixture, the mixer comprising: a vessel defining a mixing chamber therein surrounded by boundary walls; the mixture being received within the vessel, the mixture containing aggregate having a prescribed maximum diameter and lumps having a prescribed diameter that is greater than the prescribed maximum diameter therein; a plurality of mixing blades; and a driving mechanism supporting the mixing blades in the mixing chamber for mixing motion relative to the vessel so as to mix the mixture within the mixing chamber of the vessel; the mixing blades including: at least one lump conditioning blade having a rigid body terminating at a working edge along an outer side of the rigid body and which is supported by the driving mechanism so as to be movable in a working direction of rotation along a respective one of the boundary walls; said at least one lump conditioning blade having a main portion occupying a majority of a leading face of the lump conditioning blade that is oriented substantially perpendicular to said one of the boundary walls; the working edge of said at least one lump conditioning blade being oriented substantially parallel to the respective boundary wall and at an angle relative to the working direction of rotation between 60 and 90 degrees; the working edge of said at least one lump conditioning blade being supported at a prescribed space from the boundary wall which is greater than the prescribed maximum diameter of the aggregate and smaller than the prescribed lump diameter of the lumps so as to be effective to smear the lumps in the mixture against said one of the boundary walls and to reduce a lump size of the lumps in the mixture as the mixture passes between the working edge of the lump conditioning blade and the boundary wall; at least one primary blade having a rigid blade body terminating at a working edge along an outer side of the rigid body and which is supported by the driving mechanism so as to be movable in said working direction of rotation along said one of the boundary walls along the same path as said at least one lump conditioning blade in a trailing relationship relative to said at least one lump conditioning blade; the working edge of said at least one primary blade being directly adjacent to said one of the boundary walls so as to (i) be in closer proximity to said one of the boundary walls than the working edge of said at least one lump conditioning blade and (ii) be arranged to scrape the mixture from said one of the boundary walls that was smeared against said one of the boundary walls by said at least one lump conditioning blade.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of a mixer including primary mixing blades and lump conditioning blades supported therein;

(2) FIG. 2 is a side elevational view of the mixer according to FIG. 1;

(3) FIG. 3 is a section view along the line 3-3 of FIG. 2;

(4) FIG. 4 is a section view along the line 4-4 of FIG. 2;

(5) FIG. 5 is a schematic representation of an alternative embodiment of the lump conditioning blades applied to a twin shaft mixer; and

(6) FIG. 6 is a schematic representation of yet another embodiment of the lump conditioning blades applied to a pan mixer.

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

DETAILED DESCRIPTION

(8) Referring to the accompanying figures, there is illustrated a lump conditioning mixer blade generally indicated by reference numeral 10. The blade 10 is particularly suited for use with a mixer 12 of the type generally used for mixing and conditioning fine particulate material mixtures or pastes therein, for example the uniform distribution of moisture throughout a fine particle paste such as tailings, and the break-up of lumps or reduction of lump size to form an uniform and conditioned paste.

(9) The mixer 12 may take various forms as illustrated in the accompanying figures, however the invention will primarily be described with regard to the embodiment of FIGS. 1 through 4. The mixer in this instance comprises a vessel 14 having boundary walls which surround and define a mixing chamber 16 therein which receives the material to be mixed. The boundary walls as illustrated include a cylindrical wall portion 18 and a pair of end wall portions 20 at axially opposed ends of the cylindrical wall portion for enclosing the mixing chamber therein.

(10) A plurality of primary mixing blades 22 are supported on the shaft 24 of a driving mechanism to drive the mixing blades in a mixing motion relative to the boundary walls of the chamber to effectively mix the material within the mixer. The driving mechanism further includes a motor 26 supported externally of the vessel 14 which serves to drive rotation of the shaft 24 relative to the vessel which remains fixed relative to the ground. The shaft 24 is coaxial with the cylindrical wall portion 18 to permit the mixing blades 22 to be mounted on respective radially extending arms 28 fixed onto the shaft. The primary mixing blades 26 are thus supported by the driving mechanism for movement in a generally circumferential direction in a sweeping or scraping action adjacent the inner surface of the boundary wall as the shaft 24 is rotated.

(11) Each primary mixing blade 22 comprises a blade body having broad leading and trailing sides and a narrow thickness between the leading and trailing sides so as to be generally sheet-like. The leading side spans radially outward from an inner edge 30 to an opposing working outer edge 32 in close proximity to the boundary wall. The leading face of the blade body which spans between the inner and outer edges lies generally perpendicularly to the boundary wall so as to be perpendicular to a tangential plane relative to the cylindrical wall portion and the circumferential direction of motion of the blades about the axis of the shaft. The leading face is also oriented so as to be inclined relative to a normal plane which is perpendicular to the vector of motion 34. More particularly, as shown in FIG. 2, the leading face is inclined at an angle of approximately 60 degrees relative to the vector of motion 34 while remaining in a plane which is perpendicular to the boundary wall.

(12) The mixer 12 in the illustrated embodiment is particularly distinguished from the prior art by the addition of additional mixing blades presented as the lump conditioning blades 10. Each lump condition blade also includes a blade body formed to have broad leading and trailing sides and a narrow thickness between the leading and trailing sides so as to be generally sheet-like. The blade body is mounted on one or more radially extending arms 36 extending radially outward from the shaft 24. Each blade body spans radially from an inner edge 38 nearest to the axis of the shaft to an opposing outer edge 40 which is farthest from the shaft and nearest to the boundary wall of the vessel. The leading face 42 of the blade body of the lump conditioning blade 10 faces forwardly into the direction of motion which is oriented in a circumferential direction together with the movement of the primary mixing blades 22. The leading face includes an outer end portion 44 adjacent the outer edge 40 and a main portion 46 spanning radially from the inner edge 38 to the outer end portion 44.

(13) The main portion 46 of the leading face is oriented perpendicularly to the boundary wall so as to be similarly perpendicular to a plane which is tangential to the circumferential direction of motion and the cylindrical wall portion. The main portion of the leading face is also oriented to be near perpendicular to the motion vector 48 dictating the direction of motion. More particularly, the main portion of the normal vector of the leading face is preferably oriented to be between 20 degrees and parallel with the forward motion vector 48. In the illustrated embodiment, the main portion 46 is oriented at approximately 80 degrees to the motion vector 48.

(14) The outer end portion 44 of the lump conditioning blade is oriented in a trailing relationship relative to the main portion. Accordingly, the outer working edge 40 is offset rearwardly in the direction of motion 48 relative to the main portion 46. In the illustrated embodiment, the outer edge portion is curved so as to be generally convex at the leading face from the main portion 46 to the working outer edge 40. In an alternative embodiment however, the outer end portion may also have a flat planar shape which is simply angularly offset relative to the flat plane of the main portion 46 by a bend therebetween which is substantially parallel to the outer edge.

(15) The working outer edge 40 is preferably a non-linear serrated edge such that the outermost portion of the lump conditioning blade is discontinuous and interrupted therealong in the axial direction of the vessel 14.

(16) The rigid blade body of the lump conditioning blade is fixed on rigid radial arms 36 such that the working outer edge 40 is disposed in a spaced apart relationship relative to the inner surface of the boundary wall. The drive mechanism supports the lump conditioning blade such that the outer edge thereof is maintained at a fixed prescribed space from the boundary wall throughout the mixing motion as the lump conditioning blade is displaced along the boundary wall in the direction of the forward motion vector 48.

(17) The size of the gap defining the prescribed space between the outer edge 40 and the inner surface of the boundary wall may be adjustable prior to use by adjusting the mounting of the lump conditioning blade relative to the support arms 36, however, the positioning of the lump conditioning blade relative to the shaft remains fixed in operation. Typically, the gap size is selected so as to be larger than the maximum diameter of any aggregate particles expected within the material being mixed to avoid any crushing of aggregate particles within the mixture. The gap remains sufficiently small however that the gap is smaller than the expected size of lumps within the mixture to force the lumps through the gap as the blades are rotated with the shaft relative to the boundary wall to effectively reduce the size of the lumps.

(18) Each lump conditioning blade is typically mounted on the shaft of the drive mechanism in association with one or more primary mixing blades 22 in which the mixing blades are supporting in a trailing relationship relative to the lump conditioning blades. Accordingly, any area of the boundary wall over which the lump conditioning blades pass is arranged to have a subsequent primary mixing blade pass over the same area. In this arrangement, the lump conditioning blades effectively smear lumps against the boundary wall to reduce the overall diameter of the lumps and to increase the surface area of dry material within the lumps, followed by primary mixing blades which sweep and scrape the surface of the boundary wall clear of the smeared mixture thereon.

(19) Turning now to FIG. 5, according to further embodiment of the invention, a twin shaft mixer is shown in which the vessel comprises a pair of generally cylindrical wall portions 28, each coaxially locating a respective shaft 24 therein upon which primary mixing blades 22 and lump conditioning blades 10 are supported.

(20) Turning now to FIG. 6, according to another embodiment of the invention, a pan mixer is shown in which the vessel includes a flat bottom boundary wall. The drive mechanism supports primary mixing blades 22 and lump conditioning blades 10 for movement along the flat bottom boundary wall so that the outer working edges of the lump conditioning blades are maintained at a smearing gap and the primary mixing blades scrape and/or sweep the boundary wall as described above.

(21) Since various modifications can be made in the 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.