Biomixer

Abstract

A mixer 10 for biological matter comprises a housing 12 with a tapered lower portion 26, an auger comprising an auger screw 38 arranged in a sleeve 54, the screw comprises at least one blade (50, figu

Description

BIOMIXER Field The present invention relates to a mixer for biological matter. Backaround Food waste, and more generally the disposal of biological matter, is increasingly becoming an issue of intense interest due to factors such as climate change, land usage and population growth. Currently, most food waste (especially commercially produced food waste, including that from the hospitality sector) is sent to decompose in landfill sites. Whilst the biological matter disposed of in this way will eventually decompose naturally, it is a less than optimal solution due to the land usage required (that cannot be used for anything else), the loss of any remaining nutrients and the release of carbon into the atmosphere. This issue is especially prevalent in poorer countries with a large tourist industry. On tourist focused islands for example, food waste produced by hotels cannot be disposed of on land (due to the small quantities of land available). As such, this waste can often be shipped to a larger land mass (resulting in greater greenhouse gas emissions) or even dumped into the sea. Thus, it has been envisaged that such biological matter could be used as fertiliser in the vicinity of the locations in which they are produced. This has the added benefits of being able to locally source food that can provide for the local hospitality industry (that produced the waste in the first place). This would then reduce pollution to the atmosphere and to the oceans, as well as provide jobs for local people in the agriculture industry. However, such waste in its raw state is often unsuitable for use as fertiliser. It, for example, has the wrong consistency, nutrients and presence of unwanted chemicals that would result in poor crop growth. However, most fertiliser is produced in large processing plants which would be unsuitable for the above mentioned locations, due to their large size, environmental impact, cost and expertise required to run them. The present invention seeks to overcome or at least mitigate the problems described above. However, that is not to say it is limited to these situations, and more generally seeks to provide a compact, cheap and easy to operate mixer for soft, preferably biological, matter. Summary A first aspect of the invention provides a mixer for biological matter, the mixer comprising a housing having a wall, an inner surface of the wall defining a chamber, the chamber having a main portion and a lower portion arranged below the main portion, at least the inner surface of the wall of the housing tapering inwardly in the region of the lower portion; and an auger arranged inside the housing and comprising an augur screw being driveable in rotation and a sleeve, the screw being arranged within the sleeve, the sleeve having an inlet and an outlet, the outlet being arranged above the inlet, the sleeve being arranged such that the inlet is in the lower portion of the housing, whereby matter in the lower portion of the chamber may enter the augur via the inlet and be fed towards the outlet by rotation of the screw; wherein the screw has at least one blade affixed thereto; and wherein the sleeve has at least one opening arranged between the inlet and the outlet, whereby matter fed by the screw passes either through the at least one opening or through the outlet and falls back into the chamber. The provision of such a mixer provides a compact, easy to operate and cheap device that can be used in the initial processing steps of waste biological matter. The device can easily be located on the premises of hospitality industry venues and can be operated without the expertise required to run a full-scale processing plant. With the use of the correct additives and other chemicals, the biological matter suitably reduced inside by the at least one blade can then be left to compost before being used as fertiliser. The chamber may have an upper portion arranged above the main and lower portions and wherein the inner surface of the wall of the housing tapers inwardly in the region of the upper portion of the chamber. The housing may have an inlet for feeding matter into the mixer, preferably wherein the inlet is located in the upper portion of the housing wall. The housing may have an outlet for removing chopped matter from the mixer, preferably wherein the outlet is located in the lower portion of the housing wall. In this way, the matter to be processed can be easily inserted into the device and the processed matter easily removed from the device. The mixer may further comprise a drive means arranged to rotate the auger screw. This allows for driven rotation of the auger screw to drive the processing of the matter in the chamber. The mixer may further comprise a frame arranged to support the other components of the mixer. In this way, the components of the device can be within a self-contained frame that provides a stable platform. The sleeve may have at least one slot passing therethrough. At least one of the slots may be arranged at a non-parallel angle relative to a longitudinal axis of the sleeve. This angle may be in the range of 25° to 35° with respect to the longitudinal axis of the sleeve, preferably 27°. At least one of the slots may be longer than the pitch of a thread of the augur screw. At least one of the slots may be arranged such that matter forced against an internal wall of the sleeve passes through the at least one slot, said at least one slot exerting a cutting action on the matter as the matter is squeezed out through the at least one slot. These slots aid the processing of the matter, by allowing smaller pieces of matter to exit the sleeve, receiving additional cutting action, before reaching the top of said sleeve. The larger pieces of matter then experience longer in the sleeve and thus experience more cutting action from the blade(s) of the auger screw. At least one of the blades may be substantially triangular or trapezoidal in shape. The blades may be affixed only to the bottom two rotations of the auger screw. Furthermore, the blades may be affixed to the auger screw in a symmetrical fashion when viewed along a longitudinal axis of the auger. The blades may be arranged such that they are spaced evenly when viewed along a longitudinal axis of the auger. The blades may be affixed to the auger screw whereby four blades are visible when viewed along a longitudinal axis of the auger. There may be at least six blades affixed to the auger screw. At least one of the blades may be affixed to a lower surface of the auger screw. At least one of the blades may be affixed by an upper surface of said blade. At least one of the blades may be affixed to the auger screw by welding, screw and nut or other such attachment means. Alternatively, at least one of the blades may be integral with the auger screw. By optimising the shape, orientation and arrangement of the blades, the effectiveness of the blades can be increased. Different manufacturing methods are available to suit different scenarios, aid in production and maintenance of the device and increase the strength of the blades. The mixer may further comprise at least one sweeper arm arranged inside the lower portion of the housing, the sweeper arm having an angled member and a base plate, the base plate arranged at the bottom of the lower portion of the housing and the angled member being arranged along the tapered lower portion. This sweeper arm catches any matter stuck to the inner surface of the lower portion of the housing. In this way, a more even mix can be produced. The base plate may have a series of holes therethrough. A shaft of the auger screw may be arranged through a central hole of the base plate. A series of bolt holes may be arranged around the central hole of the base plate, preferably in a circular pattern. The bolt holes may be of non-equal diameter. The bolt holes may be located in circular recesses in the base plate. The base plate may be secured to an end of a shaft of the auger screw via bolts located through the bolt holes of the base plate. These features allow for the rotation of the sweeper arm in parallel with the auger screw. The sweeper arm can then better catch matter stuck to the inner surface of the lower portion of the housing. The sweeper arm may further comprise a support brace affixed to the angled member and the base plate. The support brace may be arranged to be on a downstream side of the angled member with respect to a direction of rotation of the auger screw. This ensures that the angled member does not break under the pressure of the rotating matter. The sweeper arm may further comprise at least one tooth affixed to the angled member. Furthermore, the sweeper arm may further comprise two teeth, one arranged proximate to a free end of the angled member, the other arranged proximate to the base plate. At least one tooth may be arranged to be on an upstream side of the angled member with respect to a direction of rotation of the auger screw. At least one tooth may be arranged such that it extends into a space formed between the angled member and the lower portion of the housing. The teeth pull matter stuck on the inner surface of the lower portion of the housing away, further ensuring a more even mix. The angled member may be arranged in a non-parallel fashion to the taper of the lower portion of the housing. Optimising the angle of the angled member can ensure a better removal of matter stuck on the inner surface of the lower portion of the housing. The mixer may further comprise a loading system whereby matter is fed into the mixer, the loading system comprising lifting apparatus arranged to lift the matter from proximate the lower portion of the chamber to proximate the top of the chamber where the matter is fed into the chamber via an opening. The lifting apparatus may be arranged to automatically rotate when at its highest position to feed the matter into the chamber. The lifting apparatus may be formed to fit a standard wheelie bin. The loading mechanism provides a quick and easy method of loading matter into the mixer that can be used with a standard wheelie bin, a common food waste disposal method that also allows for easy transport of matter to the mixer. A second aspect of the invention provides a method for processing biological matter, the method comprising steps of (a) placing the matter in a mixer, the mixer comprising a housing having a wall, the inner surface of which wall defines a chamber, the chamber having a main portion and a lower portion, arranged below the main portion, at least the inner surface of the wall of the housing tapering inwardly in the region of the lower portion; and an auger arranged inside the housing and comprising an augur screw being driveable in rotation and a sleeve, the screw being arranged within the sleeve, the sleeve having an inlet and an outlet, the outlet being arranged above the inlet, the sleeve being arranged such that the inlet is in the lower portion of the housing; wherein the screw has at least one blade affixed thereto; and wherein the sleeve has at least one opening arranged between the inlet and the outlet; (b) operating the mixer whereby the matter in the lower portion of the chamber may enter the auger via the inlet and be fed towards the outlet by rotation of the screw; and (c) operating the mixer whereby matter fed by the screw passes either through the at least one opening or through the outlet and falls back into the chamber. The provision of such a method allows for the relatively cheap and easy production of materials that can be composted to produce fertiliser. Brief Description of the Drawings Embodiments will now be described, by way of example only, with reference to the accompanying figures, in which: FIGURE 1 is a side view of a mixer according to the present invention; FIGURE 2 is a cross-section taken along the line A-A in Figure 1; FIGURE 3 is a view of detail B of Figure 2; FIGURE 4 is a perspective view of an auger screw according to the present invention; FIGURE 5 is a side view of the auger screw of Figure 4; FIGURE 6 is an end view of the auger according to the present invention; FIGURE 7 is a perspective view of a sweeper arm according to the present invention; FIGURE 8 is a top view of the sweeper arm of Figure 7; FIGURE 9 is a top view of the sweeper arm of Figures 7 and 8; and FIGURE 10 is a second side view of the sweeper arm according to Figures 7 to 9. Detailed Description of Embodiments Figure 1 shows a mixer 10 according to the invention. The mixer 10 comprises a housing 12 and a frame 14. The frame 14 sits around and supports the housing 12 and the other components of the mixer 10. Within the frame 14, the housing 12 is positioned above a drive means 16. This drive means 16 may be an internal combustion engine or an electric motor and is used to drive the mixer via a drive shaft 18, as will be discussed in further detail below. The bottom of the frame 14 is adapted such that it provides a stable footing on the surface upon which the mixer 10 is to be placed. At the bottom of the housing 12, proximate the drive means 16, there may also be a counterweight present (not shown), in order to reduce the centre of gravity of the mixer 10 and prevent it from toppling over. Affixed to the frame 14 there is also a control panel (not shown) by which the mixer 10 is controlled. Figure 2 shows a section cut-through view along the line A-A in Figure 1. A loading mechanism 20 is shown that is also affixed to the frame 14. The functioning of this loading mechanism 20 will be discussed in further detail below. The frame 14 is made of steel box section parts that are welded and / or bolted together. However, other suitable constructions and methods of manufacture of the frame 14 are possible, such as casting, adhesion or other pipe geometry / material. The housing 12 has a wall 22 that forms a chamber 24 therein. The chamber 24 has a lower portion 26, a main portion 28 and an upper portion 30. The main portion 28 is substantially cylindrical and lies between the lower portion 26 and the upper portion 30. The lower portion 26 and upper portion 30 extend away from the main portion 28 and also taper inwardly away from said main portion 28. It is noted that, from a mid-section of the main portion 28, the chamber 24 is symmetrical. The upper portion 30 has an inlet 32 for the feeding of biological matter to be mixed. The lower portion 26 has an outlet 34 for removing matter when it is sufficiently mixed. The outlet 34 is closed off by a door. Arranged inside the housing 12 is an auger 36 and a sweeper arm assembly 62. The auger 36 comprises an auger screw 38 and a cylindrical sleeve 54. The auger 36 is arranged such that it is vertical and is located along the central vertical axis of the chamber 24. The auger screw 38 (Fig. 4) comprises a shaft 40 and a helical thread 42. The shaft 40 has a lower end 44 which is arranged to be coupled to the drive shaft 18 and an upper end 46, arranged to be received in a bearing in the upper portion of the mixer. The thread 42 extends from the lower end 44 towards the upper end 46 of the shaft 40 but terminates short of the upper end 46. A circular end plate 48 is arranged at the lower end of the shaft 40. The end plate has a series of holes formed therethrough equally angularly spaced thereabout, which receive bolts 52. On the first two revolutions of the thread 42, starting from the lower end 44 of the shaft 40, six blades 50 are affixed to the thread. The blades project radially outwardly from the outer edge of the thread 42 and are equally spaced from each other at 90 degree intervals. The blades 50 are welded to the thread 42. The blades 50 are substantially triangular or trapezoidal in shape and are suitably sharpened to provide appropriate cutting action. The blades 50 are arranged such that from the end view (as shown in Figure 6) there are only four visible blades 50. The sleeve 54 is a hollow cylinder with a series of slots 60 formed therethrough (see Fig. 2). These slots 60 are spaced apart along the length of the sleeve 54 and are each arranged inclined relative to the longitudinal axis of the sleeve 54. Each slot is preferably slightly longer than the pitch of the augur screw thread. The sleeve 54 is shorter in axial extent than the thread 42 on the shaft 40. The sweeper arm assembly 62 comprises an inclined sweeper arm 64 extending from a base plate 66 and a support brace 68 connected to the arm 64 and base plate 66. The base plate 66 comprises a central hole 72 for the passage of the auger screw shaft 40 and drive shaft 18, which central hole defines an axis of rotation of the sweeper arm assembly 62. The base plate 66 further comprises holes 74 to allow the passage of bolts 52. The inclined sweeper arm extends both radially outwardly from the base plate 66 and axially. The support brace 68 is connected to a first edge of the sweeper arm 64. Two teeth 70 extend from the opposite, second edge of the sweeper arm, one tooth being arranged substantially adjacent the base plate 66 and the other tooth being arranged spaced from the base plate 66 adjacent the free end of the sweeper arm 64. The edge second edge of the sweeper arm is chamfered to form a blade-like cross section. On assembly, the end plate 48 of the shaft 40 of the augur 36 is arranged against the base plate 66 of the sweeper arm assembly such that the lower end of the shaft 40 extends through the central hole 72 of the base plate. Bolts 52 extend through the holes in the end plate 48 and the holes 74 in the base plate 66 and are secured with nuts. That secures the sweeper arm assembly to the augur 36 in a rotationally fast manner. In that way, rotation of the augur 36 rotates the sweeper arm 64. The augur shaft is then arranged within the sleeve 54 so that part of the thread protrudes from the sleeve 54 at each end thereof, defining a sleeve inlet 56 proximate the lower end of the shaft and a sleeve outlet 58 proximate the upper end 46 of the shaft. The augur, sleeve and sweeper arm thus form an augur / sweeper sub-assembly. The augur / sweeper sub-assembly is oriented vertically within the chamber 24. The lower end of the augur shaft is coupled to the drive shaft 18 and the upper end 46 of the augur shaft is received in a bearing at the top of the upper portion. The sleeve inlet 56 is arranged in the narrowed part of the lower portion of the chamber 24 and the sleeve outlet 58 is arranged at the uppermost part of the central portion of the chamber 24. The sweeper arm 64 is inclined at substantially the same angle relative to the axis of the shaft 40 as the taper of the lower portion. The second, chamfered edge of the sweeper arm 64 is arranged as the leading edge of the arm when driven in rotation by the drive shaft 18. It is thus envisaged that the mixer 10 operates as follows: The auger screw shaft 40 is driven in rotation by the drive means 16, via the drive shaft 18. The auger screw 38 is arranged in the sleeve 54 such that material within the sleeve is carried upwards by the thread 42 of the auger screw 38 due to traditional auger action. The loading mechanism 20 (which is arranged to cooperate with a standard size wheelie bin 76) lifts the wheelie bin 76 up proximate to the upper chamber portion 30. The loading mechanism 18 then rotates the wheelie bin 76 automatically, tipping any biological matter waste therein into the chamber 24 via inlet 32. The inputted biological matter then falls to the lower chamber portion 26. The sloping walls of the lower portion force material under gravity both downwardly but also radially inwardly towards the sleeve inlet 56. Material which is forced by that action towards the inlet of the sleeve is subjected to a slicing action by virtue of the blades 50. This material is then pulled up through the auger sleeve 54 via the rotation of auger screw 38, being subjected to a cutting action as it moves upwards from the sleeve inlet 56. The material is also forced against the wall of the sleeve and the slots in the sleeve exert a further cutting action on the material as material is squeezed out through the slots. Any matter small enough then falls through slots 60 in the sleeve 54 until the largest pieces of matter emerge from the sleeve outlet 58 and fall back down into the lower portion 26 of the chamber 24. This cycle repeats until the matter is sufficiently mixed and chopped. The sweeper arm 64 rotates with the augur shaft 40. The teeth 70 and the chamfered leading edge scrape material which has become stuck to the inner wall of the chamber 24, ensuring no material is left stuck. The support brace 68 is arranged relative to the sweeper arm 64 and is of a shape such that material dislodged by the sweeper arm is guided radially inwardly and downwardly towards the sleeve inlet 56. Once the material has been sufficiently mixed and chopped then the door of the outlet 34 can be opened to allow the processed material to be collected. Chemicals may a or prepare mz use as fertiliser an composting.

Claims

Claims 1. A mixer for biological matter, the mixer comprising: a housing having a wall, an inner surface of the wall defining a chamber, the chamber having a main portion and a lower portion arranged below the main portion, at least the inner surface of the wall of the housing tapering inwardly in the region of the lower portion; and an auger arranged inside the housing and comprising an augur screw being driveable in rotation and a sleeve, the screw being arranged within the sleeve, the sleeve having an inlet and an outlet, the outlet being arranged above the inlet, the sleeve being arranged such that the inlet is in the lower portion of the housing, whereby matter in the lower portion of the chamber may enter the augur via the inlet and be fed towards the outlet by rotation of the screw; wherein the screw has at least one blade affixed thereto; and wherein the sleeve has at least one opening arranged between the inlet and the outlet, whereby matter fed by the screw passes either through the at least one opening or through the outlet and falls back into the chamber.

2. The mixer of claim 1, wherein the chamber has an upper portion arranged above the main and lower portions and wherein the inner surface of the wall of the housing tapers inwardly in the region of the upper portion of the chamber. 3: The mixer of claim 2, wherein the housing has an inlet for feeding matter into the mixer, preferably wherein the inlet is located in the upper portion of the housing wall.

4. The mixer of claim 2, wherein the housing has an outlet for removing chopped matter from the mixer, preferably wherein the outlet is located in the lower portion of the housing wall. 5 The mixer of any of the preceding claims, further comprising a drive means arranged to rotate the auger screw.

6. The mixer of any of the preceding claims, further comprising a frame arranged to support the other components of the mixer. 7: The mixer of any of the preceding claims, wherein the sleeve has at least one slot passing therethrough.

8. The mixer of claim 7, wherein at least one of the slots is arranged at a non-parallel angle relative to a longitudinal axis of the sleeve. 5 The mixer of claim 8, wherein at least one of the slots is arranged at an angle of 25° to 35° with respect to the longitudinal axis of the sleeve, preferably 27°.

10. The mixer of any of claims 7 to 9, wherein at least one of the slots is longer than the pitch of a thread of the augur screw.

11. The mixer of any of claims 7 to 10, wherein at least one of the slots is arranged such that matter forced against an internal wall of the sleeve passes through the at least one slot, said at least one slot exerting a cutting action on the matter as the matter is squeezed out through the at least one slot.

12. The mixer of any of the preceding claims, the sleeve is axial shorter than a thread of the augur screw.

13. The mixer of any of the preceding claims, wherein at least one of the blades is substantially triangular or trapezoidal in shape. 14, The mixer of any of the preceding claims, wherein blades are affixed only to the bottom two rotations of the auger screw. 15; The mixer of any of the preceding claims, wherein the blades are affixed to the auger screw in a symmetrical fashion when viewed along a longitudinal axis of the auger.

16. The mixer of any of the preceding claims, wherein the blades are arranged such that they are spaced evenly when viewed along a longitudinal axis of the auger.

17. The mixer of any of the preceding claims, wherein the blades are affixed to the auger screw whereby four blades are visible when viewed along a longitudinal axis of the auger.

18. The mixer of any of the preceding claims, wherein there are at least six blades affixed to the auger screw.

19. The mixer of any of the preceding claims, wherein at least one of the blades is affixed to a lower surface of the auger screw.

20. The mixer of any of the preceding claims, wherein at least one of the blades is affixed by an upper surface of said blade. 2: The mixer of any of the preceding claims, wherein at least one of the blades is affixed to the auger screw by welding, screw and nut or other such attachment means.

22. The mixer of any of claims 1 to 20, wherein at least one of the blades is integral with the auger screw.

23. The mixer of any of the preceding claims, further comprising at least one sweeper arm arranged inside the lower portion of the housing, the sweeper arm having an angled member and a base plate, the base plate arranged at the bottom of the lower portion of the housing and the angled member being arranged along the tapered lower portion.

24. The mixer of claim 23, wherein the base plate has a series of holes therethrough.

25. The mixer of claim 24, wherein a shaft of the auger screw is arranged through a central hole of the base plate.

26. The mixer of claim 25, wherein a series of bolt holes are arranged around the central hole of the base plate, preferably in a circular pattern.

27. The mixer of claim 26, wherein the bolt holes are of non-equal diameter.

28. The mixer of claims 26 or 27, wherein the bolt holes are located in circular recesses in the base plate.

29. The mixer of any of claims 26 to 28, wherein the base plate is secured to an end of a shaft of the auger screw via bolts located through the bolt holes of the base plate.

30. The mixer of any of claims 23 to 29, wherein the sweeper arm further comprises a support brace affixed to the angled member and the base plate. 31 The mixer of claim 30, wherein the support brace is arranged to be on a downstream side of the angled member with respect to a direction of rotation of the auger screw.

32. The mixer of any of claims 23 to 31, wherein the sweeper arm further comprises at least one tooth affixed to the angled member.

33. The mixer of any of claims 23 to 32, wherein the sweeper arm further comprises two teeth, one arranged proximate to a free end of the angled member, the other arranged proximate to the base plate.

34. The mixer of claims 32 or 33, wherein at least one tooth is arranged to be on an upstream side of the angled member with respect to a direction of rotation of the auger Screw.

35. The mixer of any of claims 32 to 34, wherein at least one tooth is arranged such that it extends into a space formed between the angled member and the lower portion of the housing.

36. The mixer of any of claims 23 to 35, wherein the angled member is arranged in a non-parallel fashion to the taper of the lower portion of the housing.

37. The mixer of any of the preceding claims, wherein the mixer further comprises a loading system whereby matter is fed into the mixer, the loading system comprising lifting apparatus arranged to lift the matter from proximate the lower portion of the chamber to proximate the top of the chamber where the matter is fed into the chamber via an opening.

38. The mixer of claim 37, wherein the lifting apparatus is arranged to automatically rotate when at its highest position to feed the matter into the chamber.

39. The mixer of claims 37 or 38, wherein the lifting apparatus is formed to fit a standard wheelie bin.

40. A method for processing biological matter, the method comprising steps of: (a) placing the matter in a mixer, the mixer comprising: a housing having a wall, the inner surface of which wall defines a chamber, the chamber having a main portion and a lower portion, arranged below the main portion, at least the inner surface of the wall of the housing tapering inwardly in the region of the lower portion; and an auger arranged inside the housing and comprising an augur screw being driveable in rotation and a sleeve, the screw being arranged within the sleeve, the sleeve having an inlet and an outlet, the outlet being arranged above the inlet, the sleeve being arranged such that the inlet is in the lower portion of the housing; wherein the screw has at least one blade affixed thereto; and wherein the sleeve has at least one opening arranged between the inlet and the outlet; (b) operating the mixer whereby the matter in the lower portion of the chamber may enter the auger via the inlet and be fed towards the outlet by rotation of the screw; and (c) operating the mixer whereby matter fed by the screw passes either through the at least one opening or through the outlet and falls back into the chamber.

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