WO2016162436A1

WO2016162436A1 - Slurry agitator with mixing unit

Info

Publication number: WO2016162436A1
Application number: PCT/EP2016/057651
Authority: WO
Inventors: John Kearney; Thomas Carroll
Original assignee: John Kearney
Priority date: 2015-04-07
Filing date: 2016-04-07
Publication date: 2016-10-13

Abstract

A slurry agitator (100) comprising a means (101) for pumping slurry, an associated conduit (106) having an opening for slurry adjacent the means for pumping, at least one outlet for slurry; and a mixing means (110) having protrusions (112), wherein the mixing means is provided adjacent the conduit and in use the mixing means is driven to rotate.

Description

Title

A Slurry Agitator with Mixing Unit

Field

The present application relates to a slurry agitator and in particular a slurry agitator for use in a slurry tank or lagoon.

Background Of The Invention

Most slurry agitators are tractor powered via a PTO although they can also be electrically powered. The basic way a slurry agitator or pump works is that the pump is lowered into a slurry tank or lagoon, which is usually between 1 .5m and 4.5m deep. A powered impeller at the bottom of the pump lifts the slurry through a conduit. The slurry is then jetted out of the conduit from an outlet at high pressure. The jet of slurry passes through the unmixed slurry. To create a good mix the outlet can be moved up or down and from left to right. When mixing, the jet of slurry "punches" a hole through the unmixed slurry and over time causes the whole tank to circulate and mix.

A slurry agitator is conventionally used for mixing slurry which has been collected over a period of time, generally the winter months when animals are housed. Slurry collected in a tank or pit needs to be mixed to a uniform viscosity so that it can be easily transferred to other tanks or made ready for disposal on the field. Generally tanks are only mixed using a slurry agitator immediately prior to the transfer or removal of slurry from the tank.

If a slurry pit or tank is an awkward shape, there is limited access, or the slurry is very thick, mixing can be a very difficult and time consuming job. In particular, a crust forms on the slurry during periods of stagnation in the slurry tank e.g., during the winter months. The crust is formed by fibrous particles floating to the top of the lagoon/tank. In order to mix the slurry to the required uniform viscosity, the crust must be completely disintegrated. With respect to conventional slurry agitators, this is done exclusively by the jet of slurry that is projected from the agitator. However, it is often necessary to add large volumes of water to the slurry in order to aid in the mixing process. Mixing of slurry in this manner can be particularly time consuming task such that many wasted man hours are lost with a tractor consuming large volumes of fuel. Furthermore, the more time spent agitating or mixing the slurry the greater the loss of available Nitrogen (N) in the slurry to the atmosphere in the form of ammonia. Slurry is a valuable source of nutrients and there is an increased awareness that these nutrients should not be lost to the atmosphere before application to the field.

Another problem associated with conventional slurry agitators is they can become blocked by material in the slurry tank or lagoon. Slurry pumps are known for agitating the slurry under slatted housing for cattle. Undesired materials can enter the slurry tank through the slats. In particular, elongate material such as twine used to bind bales of bales of silage, straw or hay; as well as longer strands of fodder which can be trodden on by cattle and pressed down between the slats of the slatted house and thereby unintentionally end up in the slurry tank. This elongate material can become entangled in known slurry pumps and can cause serious blockages to the pump and damage to the equipment. Even if a conventional slurry agitator does not become blocked while mixing slurry with elongated material therein, the material remains in the slurry tank and can cause future problems. For example, different equipment used to extract the slurry from the tank can become blocked by the elongated material.

The present invention seeks to alleviate the disadvantages associated with known slurry pumps. Summary

According to the present invention there is provided a slurry agitator comprising a means for pumping slurry, an associated conduit having an opening for slurry adjacent the means for pumping, at least one outlet for slurry, a mixing means having protrusions, wherein the mixing means is provided adjacent the conduit and in use the mixing means is driven to rotate.

Advantageously, the present invention provides a mixing means which works in conjunction with the means for pumping slurry such that the slurry is mixed and macerated in a more efficient manner than the conventional slurry agitator. Optionally, the slurry agitator further comprises a cutting means cooperably positioned adjacent the mixing means and configured to shear elongated between the protrusions and the cutting means.

Advantageously, the cooperation of the cutting means and mixing means ensures that any elongated material is macerated in a manner not achievable using a conventional slurry agitator. This prevents the slurry pump or agitator from becoming blocked by elongated material.

Optionally, the protrusions comprise at least one of paddles, blades, chains and spikes. Advantageously different types of protrusion can be provided on the mixing means i.e., the most appropriate protrusion for the slurry environment may be chosen.

Optionally, the protrusions are detachable for ease of replacement. This allows new protrusions to be fitted to the mixing means or allows the protrusions to be replaced with alternative protrusions. Optionally, the cutting means comprises at least one blade positioned such that during rotation of the mixing means, the at least one blade passes between corresponding protrusions. Advantageously, the use of at least one blade ensures that any elongated material is macerated in an efficient manner. Optionally, the slurry agitator further comprises a hydraulic pump configured to drive the mixing means to rotate. Alternatively, the mixing means may be driven to rotate by the same drive means that drives the means for pumping slurry.

Optionally, a distal end of the mixing means is mounted adjacent the opening for slurry and the mixing means extends parallel to the conduit. Advantageously, this configuration ensures that mixing is achieved along the full length of the agitator. According to the present invention, there is provided a slurry agitator comprising a means for pumping slurry, an associated conduit having an opening for slurry adjacent the means for pumping, at least one outlet for slurry, a mixing means having an auger, wherein the mixing means is provided adjacent the conduit and in use the mixing means is driven to rotate.

Optionally, the slurry agitator comprises a drive means configured to drive both the means for pumping and the mixing means. This simplifies the construction of the agitator and maximises the use of a drive shaft which is part of both the means for pumping and mixing means.

Optionally, the drive means comprises a drive shaft which rotates both the means for pumping and the mixing means. Optionally, the mixing means is an impeller within a housing at a distal end of the slurry agitator. The impeller housing may include an opening wherein the auger of the mixing means is configured to convey slurry and any entrained material towards the impeller. Optionally, the mixing means may be partially enclosed within a pipe or tube.

The pipe or tubing may be open along the full length thereof. Two or more longitudinal sections of pipe or tubing may run parallel to the mixing means.

According to the present invention there is also provided a slurry agitator comprising a means for pumping slurry, an associated conduit having an opening for slurry adjacent the means for pumping, at least one outlet for slurry, and a mixing means having protrusions, wherein the mixing means is provided transverse to the conduit and in use the mixing means is driven to rotate. Brief Description Of The Drawings

The present application will now be described with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a slurry agitator according to an embodiment of the present invention; Figure 2a is a side view of a slurry agitator according to another embodiment of the present invention;

Figure 2b is a side view of a slurry agitator according to another embodiment of the present invention;

Figure 3 is a side view of a slurry agitator according to a further embodiment of the present invention;

Figure 4 is a side view of a slurry agitator according to a further embodiment of the present invention;

Figure 5 is perspective view of the a hydraulic pump that may be used in any of the embodiments of the slurry agitator of the present invention;

Figure 6 is a cut out view of a portion of the slurry agitator in accordance with the present invention;

Figure 7 is a perspective view of a slurry agitator according to a further embodiment of the present invention;

Figure 8 is a perspective view of a slurry agitator according to a further embodiment of the present invention;

Figure 9 is underside view of another embodiment of the slurry agitator of the present invention;

Figure 10 is a perspective view of a slurry agitator according to a further embodiment of the present invention; and

Figure 1 1 is a side view of the further embodiment of the slurry agitator of Figure 10.

Detailed Description Of The Drawings

The present teaching will now be described with reference to an exemplary slurry agitator. It will be understood that this exemplary slurry agitator is provided to assist in an understanding of the present teaching and is not to be construed as limiting in any fashion. Furthermore, elements or components that are described with reference to any one figure may be interchanged with those of other figures without departing from the scope of the present teaching. It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. Referring to the drawings and initially to figure 1 , there is illustrated a slurry agitator 100 in accordance with a first embodiment of the present invention. As is known in the art, the slurry agitator 100 is provided with a pumping means in the form of an impeller (not shown) within an impeller housing 101 . The impeller is driven through a gearbox 102. The most common means of driving a slurry agitator is using a power take-off (PTO) from a tractor. A PTO shaft 103 is shown for attachment between the gearbox 102 and a tractor. Lift arms 104 are attached to a frame 1 14 of the slurry agitator for mounting of the agitator on a tractor. However, the slurry agitator of the present invention does not have to be mounted on a tractor. Furthermore any suitable power source may be used to provide power to the gearbox 102 in place of a tractor.

The gearbox 102 can change the ratio of drive from the PTO shaft 103 and the direction of drive through ninety degrees. The gearbox 102 drives the impeller through a drive shaft 105. The drive shaft 105 is generally held within a housing to prevent exposure to slurry while the agitator is in a tank. As can be seen from Figure 1 the drive shaft 105 runs centrally along the length of the agitator 100. A conduit 106 for slurry runs adjacent the drive shaft 105 from the impeller housing 101 to an opening 107 at the opposite end. The conduit 106 opens into the impeller housing 101 such that the impeller pumps slurry into the conduit 106. As is known to those skilled in the art, the underside of the impeller housing 101 is open to allow slurry to enter. The conduit 106 is generally used for pumping slurry from the tank and the opening 107 may be provided with a gate valve and a coupling (not shown). An outlet pipe 108 is also provided from the impeller housing 101 and terminating in a mixing nozzle 109. If the outlet 107 of the conduit is closed, the impeller pumps slurry through the outlet pipe 108, which in turn jets out through the outlet 107. In use, the slurry agitator 100 is lowered into a slurry tank (not shown) and the impeller is powered by either a tractor or electric motor. The slurry is raised by the action of the impeller and forced into the nozzle outlet pipe 108 and through the nozzle 107, producing a high pressure jet of slurry that punches a hole in the surrounding unmixed slurry. As can also be observed from Figure 1 , the agitator of the present invention is also provided with a mixing means 1 10. As will be explained hereinafter, this mixing means 1 10 provides improved agitating and mixing of the slurry with respect to conventional slurry agitators, which rely solely on a pressure jet of slurry from the nozzle 109 for mixing.

The mixing means 1 10 comprises a mixing shaft 1 1 1 running adjacent the aforementioned drive shaft 105 and conduit 106. The mixing shaft 1 1 1 has a plurality of protrusions 1 12 thereon. In the embodiment of figure 1 , the protrusions are shown as flat plates that are attached to alternative positions on the shaft 1 1 1 . In particular, two plates 1 12 are positioned together at opposite sides of the mixing shaft and the next two plates are at ninety degrees to the previous set of plates 1 12. However, as will be explained in more detail below, any number of configurations for the protrusions 1 12 may be used. As is known in the art, the structural components of the agitator 100 are usually made of steel. In a similar manner, the mixing shaft 1 1 1 and the protrusions 1 12 are preferably fabricated from steel. A suitable diameter for the mixing shaft is 40mm but any dimensioned shaft may be used. The agitator 100 of the present embodiment is further provided with a drive means 1 13 for driving the mixing means 1 10. In the present embodiment the drive means 1 13 is a hydraulic motor. However, it will be appreciated by those skilled in the art that the drive means may be any suitable means that drives the mixing means 1 10 to rotate. For example, the drive means may be an electrical motor. Alternatively, the drive means 1 13 may be connected to the gearbox 102 (for example via a second PTO) such that the gearbox 102 also drives the mixing means. An alternative gearbox to that shown may be provided such that power from the PTO shaft 103 is provided to both the drive shaft 105 and mixing shaft 1 1 1 at the appropriate speeds.

In use, the mixing means 1 10 is exposed directly to the slurry and is driven to rotate by the drive means 1 13. The mixing means may rotate in either clockwise or anticlockwise motion. It will be appreciated that in use, the slurry agitator 100 is lowered into a slurry tank, which breaks the fibrous crust that may have formed on the slurry. To mix the slurry in a more efficient manner, the pressure jet of slurry from the nozzle 109 and the mixing means 1 10 cooperate. Specifically, the mixing means 100 mixes the slurry along the full length of the agitator 100. The jet of slurry from the nozzle 109 causes the slurry within the tank to circulate. The slurry then passes the agitator 100 and is further mixed by the mixing means 1 10. When operating, he mixing means causes an area of turbulence in the slurry around the agitator. If a piece of the fibrous crust enters the turbulent area, it is disintegrated.

In turn, the slurry that has been mixed by the mixing means 100 i.e., entered the turbulent area, is more viscous and therefore it is easier for the impeller to pump this slurry out of the nozzle 109. The time take to mix a tank of slurry is greatly reduced by the synergistic effect of the nozzle 109 and the mixing means 1 10. In practice, reductions in time by approx. 40% have been achieved when compared to mixing the same tank with a conventional slurry agitator.

Turning to Figure 2a, another embodiment of a slurry agitator 200a in accordance with the present teachings is shown. The slurry agitator 200a of this embodiment is similar to that shown in Figure 1 . However, projections 201 , which function as cutting or tearing means, are provided mounted on and extending from the conduit 106. These projections are stationary during operation of the agitator 100 and mixing means 1 10. The fixed projections 201 and the rotatable mixing means (in particular the protrusions) cooperate to provide improved mixing and maceration of the slurry. In use, any elongated material that may be in the slurry is captured in the space between the fixed projections 201 and the rotatable protrusions 1 12 of the mixing means 1 10. The fixed projections 201 and the rotatable protrusions 1 12 of the mixing means are configured to cooperate such that in use any elongate material which enters between these elements 1 12, 201 is sheared or torn by the rotation of the mixing means 1 10. Specifically, the elongated material will catch on to the projections 201 and be sheared or torn by the rotation of the protrusions 1 12. Thus elongate material is sheared before it can enter into the impeller housing 101 of the slurry agitator or pump 100 and hence clogging of the pump by such elongate material is advantageously prevented. Figure 2a also provided a better view of the mixing nozzle 109 in accordance with the invention. The outlet of the mixing nozzle 109 comprising a converging duct. The mixing nozzle 109 is attached to a rotatable drum 202 which is mounted on a nozzle box. The nozzle box is mounted on one end of the outlet pipe 108 and is supported by may be supported by a strut. The rotatable drum 202 may be rotated by means of an handle 203.

As would be understood by those skilled in the art, the projections 201 are positioned on the conduit 106 spaced apart such that each rotatable protrusion 1 12 passes between two projections 201 . The inventors have found that a suitable spacing for the projections 201 is 200mm. This is assuming the protrusions 1 12 are spaced 100m apart. However the dimensions and distance between the protrusions 1 12 and projections 201 is merely exemplary in the embodiment of Figure 2a. For example, although the projections 201 are shown as quite thin with respect to the protrusions 1 12, this may not be the case. The projections 201 may have a similar shape to the protrusions 1 12 i.e., they may be flat paddle shaped projections. In addition, the spacing between the ends of the projections 201 and the rotatable mixing shaft 1 1 1 may be different than that shown and chosen as appropriate. For example, the inventors have found that 1 10mm is a suitable spacing between the mounting of the projections 201 and the mixing shaft 1 1 1 .

With reference to Figure 2b, a further embodiment of a slurry agitator 200b in accordance with the present teachings is shown. The slurry agitator 200b of this embodiment is similar to that shown in Figure 2a. However, in this embodiment, the cutting means are not mounted on the conduit 106 but on a separate shaft 301 . The shaft 301 is fixed between the impeller housing and the frame of the agitator 200b adjacent the drive means 1 13. Mounting of the projections 201 on a separate shaft 301 provides more options with regard to replaceability. Optionally, the projections 201 are detachable for ease of replacement. This allows new projections 201 to be fitted to the shaft 301 or allows the projections to be replaced with alternative projections 201 .

Turning to Figure 3, another embodiment of the present invention is shown. In this embodiment of the agitator 300, the protrusions of the mixing means are not flat paddles but chains 301 . Again, the number and placement of the chains 301 on the mixing shaft 105 may be chosen as appropriate by those skilled in the art. In addition, the length of the chain 301 i.e., how many links, is not limited to that shown in figure 3. During rotation of the mixing means 1 10, the chains 301 would assume a horizontal position. While at rest, they chains hang down - vertical orientation.

With reference to Figure 4, another configuration of the protrusions is shown. In this embodiment, the slurry agitator 400 is provided with blade members 401 as the protrusions. The rotatable blade members 401 are mounted on the rotatable shaft 105 so that the rotatable blade members 401 rotate when the mixing shaft 1 1 1 rotates. The rotatable blade members 401 each comprise a first cutting edge and optionally a second cutting edge. Any number of blade members 401 may be provided on the shaft 105. For example, if it is desirable to ensure that any elongated material in the slurry is shredded then a large number of blade members may be provided on the mixing means 1 10. The blade members 401 may also work in conjunction with the previously described projections. Although not shown in Figure 4, projections may be mounted on the conduit 106 or a stationary shaft as previously described. The projections may be blade members similar to the blade members 401 . Alternatively any configuration for the projections may be used that cooperate with the rotations of the mixing means 1 10.

Turning to Figure 5, a more detailed view of the drive means 1 13 mounted on the agitator is provided. The drive means 1 13 in this embodiment is a hydraulic motor with hydraulic hoses 501 for attachment to the tractor (or any other source of oil). As will be understood by those skilled in the art, the drive means 1 13 operates independently from the gearbox 102, which receives power from the PTO. Advantageously, this means that in some situations where it is not necessary to use the mixing means 1 10, for example in watery slurry not containing elongated material, the mixing means can remain disengaged and thus save on fuel. This is particularly important for contractors who may encounter a number of different slurry tanks and slurry conditions on a daily basis. Furthermore, the drive means 1 13 and mixing means 1 10 can be operated without the agitator being driven via the PTO. Figure 5 also shows the mounting of the mixing means, in particular the mixing shaft 105. In this exemplary embodiment a bearings is mounted within a flanged housing 502 as the bearing mounting surface is perpendicular to the mixing shaft axis. Specifically, a 4 bold flange with a 40mm bearing is used. Such flanges are commonly available in two; three, or four-hole configurations and any suitable mounting arrangement (not limited to using a flange) may be chose as appropriate by the skilled person. A coupler may also be used with the bearing flange 501 to mount the mixing shaft 1 1 1 . Although not shown in detail in the drawings, the mixing shaft (the distal end of the mixing shaft) may also be held at the impeller housing 101 using a bearing and flange e.g. a 40mm bearing. The mixing shaft 1 1 1 is thus free to rotate.

Turning to Figure 6, this shows a cut out view of a portion of the slurry agitator in accordance with the present invention. The protrusions 1 12 may be flat plates 120mm wide and spaced apart on the mixing shaft 100mm from each other. The protrusions 1 12 may be square shaped such they are also 120mm long. However as previously mentioned, these dimensions are merely exemplary and any dimensions may be chosen as appropriate by those skilled in the art. Although not shown, the protrusions may be detachable. For example, each protrusion may be mounted to a bracket on the mixing shaft 1 1 1 using a pin or bolt. However any suitable mounting system may be used. Furthermore, the previously described projections 201 may also be detachable using a similar attachment means. Although not shown in the figures, the present teachings also provides a slurry agitator comprising a means for pumping slurry, an associated conduit having an opening for slurry adjacent the means for pumping, at least one outlet for slurry, and a mixing means having protrusions, wherein the mixing means is provided transverse to the conduit and in use the mixing means is driven to rotate. In particular, unlike the previously described embodiments, the mixing means 1 10 does not run along the length of the slurry agitator but rather across the width of the agitator. Naturally, this requires separate mountings for each end of the mixing means. This may be done by extending the previously described frame (1 14 of Figure 1 ) of the slurry agitator. Preferably, the mixing means positioned transverse to the conduit is moveable up and down along the length of the slurry agitator or a least a portion of the length of the slurry agitator. In this manner, the mixing means can be positioned to align with the position of the crust on top the slurry when the agitator is within a slurry tank. The movement of the mixing means may be performed using hydraulic rams mounted between the frame of the agitator and the mixing means. Such a mixing means may be driven using the previously describing drive means in conjunction with a gearbox to change the direction of drive through ninety degrees. With reference to Figure 7, another embodiment of the slurry agitator with mixing means in accordance with the present teachings is shown. In a similar manner as previously described with reference to figure 1 , the slurry agitator 700 is provided with a pumping means in the form of an impeller (not shown) within an impeller housing 701 . The impeller is driven through a gearbox 702. The most common means of driving a slurry agitator is using a power take-off (PTO) from a tractor. A PTO shaft 703 is shown for attachment between the gearbox 702 and a tractor. Lift arms 704 are attached to a frame 714 of the slurry agitator for mounting of the agitator to a tractor. However, the slurry agitator of the present invention does not have to be mounted to a tractor. Furthermore any suitable power source may be used to provide power to the gearbox 702 in place of a tractor.

The gearbox 702 can change the ratio of drive from the PTO shaft 703 and the direction of drive through ninety degrees. The gearbox 702 drives the impeller through a drive shaft 705. The drive shaft 705 is a shaft (that may be mounted centrally) that runs from the gearbox 702 to the impeller in the impeller housing 701 . It should be noted that unlike the previously described embodiments, the drive shaft of the previous embodiment is not held within a housing to prevent exposure to slurry while the agitator is in a tank. In fact, as will be explained in more detail, the drive shaft 705 serves two functions in this embodiment of the present invention. As can be seen from Figure 7 the drive shaft 705 runs centrally along the length of the agitator 700. In a similar manner as previously described, a conduit 706 for slurry runs adjacent the drive shaft 705 from the impeller housing 701 to an opening 707 at the opposite end. The conduit 706 opens into the impeller housing 701 such that the impeller pumps slurry into the conduit 706. As is known to those skilled in the art, the underside of the impeller housing 101 is open to allow slurry to enter (this is shown in Figure 9). The conduit 706 is generally used for pumping slurry from the tank and the opening 707 may be provided with a gate valve and a coupling (not shown).

As can be observed from Figure 7, the agitator 700 of the present embodiment is also provided with a mixing means 710. The mixing means comprises a plurality of paddles 712, which are attached to the drive shaft 705. The paddles 712 may be fixedly or removably attached the central drive shaft 705. As previously mentioned, the drive shaft 105 is exposed to the slurry in this embodiment of the agitator. During operation of the slurry agitator 700, the drive shaft 705 is rotating to drive the impeller in the housing 701 . At the same time, the rotation of the drive shaft 705 causes the paddles 712 to rotate and further mix the slurry. Specifically, the mixing means 710 mixes the slurry along the full length of the agitator 700, or at least along the full length of the drive shaft 705. When operating, the mixing means 710 causes an area of turbulence in the slurry around the agitator. If a piece of the fibrous crust enters the turbulent area, it is disintegrated. It should be appreciated that the present embodiment is not limited to use with the paddles 712 and any other suitable means such as chains, blades etc. may used in place of the paddles 712.

As will be evident to the person skilled in the art, this embodiment of the present invention does not require a secondary drive means. Specifically, this embodiment does not require a hydraulic pump 1 13 described with reference to the previous embodiments. Rather, in the embodiment shown in Figure 7, the mixing means 710 is driven by the gearbox 702. This configuration simplifies the operation of the agitator 700.

As will be appreciated by those skilled in the art, during rotation, the paddles pass between the drive shaft 805 and conduit 706. In the embodiment of Figure 7, the conduit 706 is close to the outer periphery of the impeller housing 701 . In this manner, longer paddles may be provided on the drive shaft 705. However, it will be appreciated that the conduit 706 may be positioned closer to the central drive shaft 105 and shorter paddles would be used. In some embodiments of the slurry agitator 700, the conduit 706 may not be fitted. As previously explained, the function of the conduit 706 is for pumping slurry from the impeller housing through the opening 707. That is, the function of the conduit is to pump slurry out of the tank in which the agitator 700 is placed. However, in many situations it is only desirable to mix or agitate the slurry in the tank. Other means are used to remove the mixed slurry form the tank. In these situations, the conduit 706 is not used. Therefore, an agitator may be provided without conduit 706. In such a configuration, the size of the paddles may be greatly increased. The mixing unit may rotate with a diameter approximately equal to the diameter of the impeller housing 701 .

With reference to figure 7 again, it can be observed that this embodiment of the agitator 700 is also provided with projections 708. As previously mentioned, any number of configurations for the projections 708 may be used. The fixed projections 708 and the rotatable paddles 712 of the mixing means are configured to cooperate such that in use any elongate material which enters between these elements 708, 712 is sheared or torn by the rotation of the mixing means 710. In the embodiment of Figure 7, the projections are shown at a certain distance from the paddles i.e., spaced apart from the paddles. However, any distance and spacing between the paddles 712 and the protrusions 708 may be chosen as appropriate by those skilled in the art. The protrusions 708 are mounted on a support bar or pole. Any suitable mounting unit 709, such as a frame etc., may be used to hold the protrusions 708 at their fixed positions.

It should also be understood that the protrusions 708 are optional and that the agitator may not be fitted with a mounting unit 709 or protrusions 708. In the embodiment of Figure 7, two sets of protrusions 708 are provided, each set mounted on a mounting unit 709. However, only one set of protrusions 708 may be provided. Furthermore, one set of protrusions 708 may be mounted directly on conduit 706 obviating the need for one mounting unit.

Turning to Figure 8, another embodiment of the slurry agitator 800 with mixing unit in accordance with the present teachings is shown. In this embodiment, the mixing unit 801 is different. In particular, a plurality of paddles 802 are used in a similar configuration as shown in Figure 7. However, a plurality of plates 803 are also provided. Each plate 803 is positioned between two paddles 802. In this manner, as a paddle rotates, it pushes a volume of liquid ahead of it. In particular, the volume of liquid between each two panels is pushed by a rotating paddle 802. This pushing or forcing of the liquid (slurry) between the plates causes agitation and aids in the mixing process. A close fitting between the underside of the paddles 803 and the top of the plates 803 ensures that liquid does not escape past the paddles during rotation of the paddles. That is, the close fitting ensures that any liquid or slurry between the plates 803 is forced to move by the rotation of the paddles 802. However, gaps may also be provided to reduce the volume and slurry being moved e.g. to reduce the loading on the tractor or power supply.

The plates 803 are mounted on a frame 804, which in the present embodiment comprises two bars or poles. However, any suitable mounting means may be used in place of the frame 804. The drive shaft 805 passes through the plates 803 and must be free to rotate i.e., the plates 803 do not impinge on the rotation of the drive shaft 805. As previously described, the drive shaft 805 may be centrally mounted and runs from the gearbox to the impeller in the impeller housing.

With reference to Figure 9, another embodiment of the present invention is shown. In particular, a feature is provided that may be used with any of the herein described embodiments. Furthermore, this feature may be employed on conventional slurry agitators. The underside of a slurry agitator is shown in Figure 9. From this view, the previously described outlet 107 and outlet pipe 108 can also be seen. Furthermore, the underside of an impeller housing 901 is shown. An impeller 902 protrudes from a central opening 903, through which slurry is pulled or sucked by rotation of the impeller 902. The configuration for the impeller 902 shown is merely exemplary and any number of configurations known to those skilled in the art may be used.

As is known in the art, elongated material within the slurry gets pulled into the central opening 903 with the slurry. Such elongated material may block the outlet pipe 108 or outlet 107. However, in the impeller shown in Figure 9, blades 904 are providing on the underside of the impeller housing 901 . In particular, the blades 904 protrude slightly over the opening 903. With this configuration, elongated material that is pulled towards the opening 904 makes contact with the blades 904. The blades 904 have a sharp serrated edge 905. When the elongated material makes contact with the blades as it is passing the blades the material is torn or shredded by the serrated edge 905.

Any number of blades 904 may be provided on the impeller housing. The use of two blades in the embodiment of Figure 9 is merely exemplary. Furthermore, the shape of the blades may be chose as appropriate. However, the serrated edge 905 should match the shape of the circular opening. In this case, the blades have an arcuate shape cutting edge i.e., the serrated edge. The amount of protrusion of the blades towards the centre of the central opening 903 can also be chosen as appropriate by the skilled person. However, it has been found that approx. 5mm is an optimal amount. If the blades protrude too far, the central opening may be blocked and/or material is inhibited from entering the opening 905.

With reference to Figure 10, another embodiment of the slurry agitator with mixing means in accordance with the present teachings is shown. In a similar manner as previously described with reference to Figure 1 , the slurry agitator 1 100 is provided with a pumping means in the form of an impeller within an impeller housing 1 101 . This embodiment of the slurry agitator 1 100 differs from the previous embodiments in that an aperture 1 102 is provided on top of the impeller housing and not underneath. Conventionally, slurry enters the impeller housing 1 101 from the underside - the distal end of the impeller housing. However, in this embodiment slurry enters from the topside - the proximal end of the impeller housing 1 101 . It should be appreciated that this embodiment is not limited to providing the opening 1 102 at the top of the impeller housing and it may also be provided underneath in accordance with the previously described embodiments.

The impeller is driven through a gearbox 1 103. The most common means of driving a slurry agitator is using a power take-off (PTO) from a tractor. A PTO shaft 1 104 is shown for attachment between the gearbox 1 103 and a tractor (not shown). Lift arms 1 105 are attached to a frame 1 106 of the slurry agitator for mounting of the agitator to a tractor. However, the slurry agitator of the present invention does not have to be mounted to a tractor. Furthermore any suitable power source may be used to provide power to the gearbox 1 103 in place of a tractor. The gearbox 1 103 changes the ratio of drive from the PTO shaft 1 104 and the direction of drive through ninety degrees. The gearbox 1 103 drives or rotates the impeller by rotating a drive shaft 1 107. In a similar manner as some previous embodiments of the slurry agitator shown, the drive shaft 1 107 is not held within a housing to prevent exposure to slurry while the agitator is in a tank. The drive shaft 1 107 serves two functions in this embodiment of the present invention. As can be seen from Figure 10 the drive shaft 1 107 runs along the length of the agitator 1 100.

The drive shaft 1 107 may be centrally located along the slurry agitator or offset from the centre. In a similar manner as previously described, a conduit for slurry (not shown) may run adjacent the drive shaft 1 107 from the impeller housing 1 101 to an area adjacent the gear box 1 103. The conduit may open into the impeller housing 1 101 such that the impeller pumps slurry into the conduit. Slurry may enter the opening 1 102 on the topside of the impeller housing 1 101 to allow slurry to enter the housing 1 101 .

An outlet pipe 1 1 10 is also provided leading from the impeller housing 1 101 and terminating in a mixing nozzle. As will be described in more detail, slurry is pulled into the impeller housing 1 102 by the action of the impeller 1 102 and forced into the outlet pipe 1 1 10 and through a nozzle 107 at the end of the outlet pipe. This produces a high pressure jet of slurry that punches a hole in the surrounding unmixed slurry.

As can be observed from Figure 10, the agitator 1 100 of the present embodiment is also provided with a mixing means 1 108. The mixing means 1 108 comprises a screw conveyer. A screw conveyor or auger conveyor is a mechanism that uses a rotating helical screw blade, called a "flighting" to move liquid or granular materials. It can be observed that the mixing means 1 108, screw conveyer or auger comprises a spiral blade coiled around the drive shaft 1 107. The rate of volume transfer is proportional to the rotation rate of the shaft. During operation of the slurry agitator 1 100, the drive shaft 1 107 is rotating to drive the impeller in the housing 1 101 . At the same time, the rotation of the drive shaft 1 107 causes the mixing means 1 108 to mix the slurry. Specifically, the mixing means 1 107 or auger pulls the slurry in a downward direction. That is, rotation of the auger 1 108 conveys slurry towards the opening 1 102 in the impeller housing 1 101 . Once the slurry enters the impeller housing 1 102, it is pumped out through the outlet pipe 108 as previously described. It will also be appreciated that the rotation of the mixing means mixes the slurry along the full length of the agitator 1 100, or at least along the full length of the drive shaft 1 107. When operating, the mixing means 1 108 causes an area of turbulence in the slurry around the agitator. If a piece of the fibrous crust enters the turbulent area, it is disintegrated.

Furthermore, the mixing means 1 108 in the form of an auger, pulls any crust that has formed on the top of the slurry downwards towards the opening 1 102. In this manner, the crust can be disintegrated much more quickly when compared to a conventional slurry agitator. As is known in the art, the crust that forms on the slurry during periods of stagnation can float around during mixing of the slurry and escape agitation. However, during operation, the slurry agitator 1 100 of the present embodiment creates an area of attraction (e.g. whirlpool) that draws any pieces of crusts floating on the slurry.

As will be evident to the person skilled in the art, this embodiment of the present invention does not require a secondary drive means. Specifically, this embodiment does not require a hydraulic pump described with reference to some previous embodiments. Rather, in the embodiment shown in Figure 10, the mixing means 1 108 is driven by the gearbox 1 103. This configuration simplifies the operation of the agitator 1 100. Turning to Figure 1 1 , a side view of the slurry agitator 1 100 of Figure 10 is shown. It can be observed that this embodiment of the agitator 1 100 is provided with a support frame in the form of parallel pipes or solid bars 1201 . These pipes are extensions of the previously described frame 1 106. They act to hold or connect the impeller housing 1 101 to the frame 1 106. In turn the impeller housing 1 101 is also an extension of the frame 1 106. The impeller housing 1 101 holds the drive shaft 1 107 in place. In particular, a bearing mounting 1202 is provided at the underside of the impeller housing 1 101 . It will be appreciated that the mixing means 1 108 is driven at one end and held in the bearing mounting 1202 at the opposite end. The drive shaft 1 107 is free to rotate within the bearing mounting 1202.

Alternative configurations for the parallel pipes 1201 of Figures 10 and 1 1 may be provided. For example, the mixing means may be partially enclosed by curved or rolled sheet metal in place of the pipes 1201 . A screw conveyer or auger is often enclosed within a tube or housing. In this manner, the maximum amount of material may be conveyed by the auger. Partially enclosing the mixing means of the present embodiment of the agitator ensures the more material is conveyed towards the impeller 1203. At the same time, slurry and entrained material may also enter a mixing area (area within which the mixing means 1 108 is mixing) from the side or laterally.

In another configuration, lips may be provided on the auger. In particular, downward facing lips of any length may be provided on the external periphery of the auger. The lips may be continuous or broken. The provision of the lips means that during operation, the slurry is inhibited from escaping laterally from the mixing area. That is, the lips aid in guiding or directing the slurry towards the impeller 1203.

The impeller housing 1 101 is shown occupying a relatively small portion of the length of the agitator. The housing may be extended to be longer i.e., to extend towards the proximal end of the of the slurry agitator 1 100. This would mean the mixing means 1 108 having an auger would have to be shortened.

The embodiment described with reference to Figures 10 and 1 1 could also be combined with the any of the previous embodiments. Taking the embodiment shown in Figure 7 as an example, a plurality of paddles attached to a first portion of the drive shaft 1 107 may be provided while an auger is attached to a second portion of the drive shaft 1 107. Projections may be provided adjacent the drive shaft, which function as the previously described cutting or tearing means. The blades described with reference to Figure 9 may also be incorporated around the opening 1 102. In another embodiment, the opening 1 102 may be larger such that the diameter of the opening is equal or larger than the diameter of the auger or mixing means 1 108.

The words comprises/comprising when used in this specification are to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers , steps, components or groups thereof.

It will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention as defined in the appended claims.

Claims

1 . A slurry agitator comprising

a means for pumping slurry;

an associated conduit having an opening for slurry adjacent the means for pumping;

at least one outlet for slurry; and

a mixing means having protrusions, wherein the mixing means is provided adjacent the conduit and in use the mixing means is driven to rotate.

2. The slurry agitator of claim 1 further comprising

a cutting means cooperably positioned adjacent the mixing means and configured to shear elongated between the protrusions and the cutting means.

3. The slurry agitator of claim 1 or 2 wherein the protrusions comprise at least one of paddles, blades, chains and spikes.

4. The slurry agitator of any one of any one of claims 1 to 3 wherein the cutting means comprises at least one projection positioned such that during rotation of the mixing means the at least one projection passes between corresponding protrusions.

5. The slurry agitator of claim 4 wherein the at least one projection comprises at least one of paddles, blades, chains and spikes.

6. The slurry agitator of any one of claims 1 to 5 wherein the mixing means comprises a shaft that runs along the length of the slurry agitator.

7. The slurry agitator of claim 6 further comprising a motor wherein the shaft is driven to rotate by the motor.

8. The slurry agitator of claim 7 wherein the motor is a hydraulic motor or an electric motor.

9. The agitator of any claim 7 or 8 wherein the means for pumping slurry is driven by a power source that is operable independently from the motor.

10. The agitator of any one of claims 6 to 9 wherein the shaft runs from the means for pumping slurry at a distal end of the agitator to the pump at a proximal end of the agitator.

1 1 . The slurry agitator of claim 6 wherein the means for pumping slurry is driven by a power means and the shaft is driven to rotate by the same power means.

12. The slurry agitator of claim 1 1 wherein the shaft runs from the means for pumping slurry at a distal end of the agitator to a gearbox, for attachment to the power means, at a proximal end of the agitator.

13. The slurry agitator of any one of claims 6, 1 1 and 12 wherein the shaft is mounted along the longitudinal axis of the agitator.

14. The slurry agitator of any one of claims 1 to 13 wherein the protrusions are detachable and replaceable.

15. The slurry agitator of any one of claims 4 to 14 wherein the projections are detachable and replaceable.

16. The slurry agitator of claim 1 wherein the mixing means comprises an auger and in use the mixing means is driven to rotate.

17. The slurry agitator of claim 16 wherein the auger is configured to convey slurry towards the pumping means.

18. The slurry agitator of any one of claims 1 to 17 wherein the means for pumping slurry is an impeller within an impeller housing.