GB2151948A - Separation equipment - Google Patents

Abstract

An apparatus 10 for separating worms from a worm-containing medium comprises an upwardly-moving spiked conveyor 12 receiving the medium from a hopper 14. In operation, worm free material will run down between the spikes 30 into a first receptacle 20 whereas worms clinging to the spikes will only leave the conveyor when they slip down the inverted spikes of the return run of the conveyor to fall into the worm receptacle 21. In an alternative embodiment, the separating mechanism is provided by an internally-spiked drum member into which the medium is loaded. As the drum rotates, the internal surface of the drum becomes increasingly steep until at least the bulk of the medium is left behind. The worms, on the other hand, become draped over the spikes on the drum until these become sufficiently inverted for the worms to slide off on to a collection belt running down the centre of the drum. <IMAGE>

Description

SPECIFICATION Separation equipment The present invention relates to separation equipment and in particular, but not exclusively, to separation equipment for the separation of worms from a worm-containing organic medium e.g. as derived from animal and/or vegetable wastes processed in accordance with the method of UKPA 8318084 (NRDC).

The processed medium referred to above is a fine tilth of peat-like appearance which is found to be a valuable agricultural material useful as a plant food, soil conditioner or a plant growing substrate.

The worms themselves have a high protein content and when separated from the processed waste they can be used as a feed additive e.g. for fishfarming, or for pigs or poultry.

One method of separating out the worms is to sieve the worm-containing medium in a cylindrical rotating sieve having graded mesh sizes which pass the peat-like medium but not the worms which are collected downstream.

An object of the invention is to provide a more efficient system for separating the worms from the worm-containing medium.

According to the present invention, an apparatus for separating worms from a medium containing the worms comprises an endless spike-carrying conveyor surface for the medium and/or worms and drive means for moving the surface over an endless path in which firstly the surface is or becomes sufficiently steep for at least the bulk of the medium to be left behind and the worms become draped over the spikes and secondly the spikes thereafter become increasingly inverted until gravity causes the worms to slide off the spikes for col lection beneath the spikes when so inverted.

Conveniently, the conveyor surface is provided by an externally spiked belt or drum member.

Conveniently, in this case, the apparatus includes worm collection means comprising a receptacle or a receptacle preceded by a second worm-separating apparatus e.g. as described and claimed in copending Patent Application 8334551 (NRDC).

Conveniently, the apparatus includes supply means comprising a vibrating plate inclined downwardly towards said inclined run of the conveyor.

In alternative embodiments, the conveyor surface is instead provided by an internally spiked belt or drum member.

In the first of these cases, the belt may conveniently be supported on rollers or like support means engaging the conveyor surface between the spikes.

In the second case, the drum member conveniently takes the form of an open spike-conveying framework of squirrel cage of helical form.

In this latter instance, the apparatus preferably includes supply means in the form of a cylindrical or part-cylindrical container embracing or at least in part embracing the drum member so that, on rotation of the drum member, the spikes will sweep through the medium containing space of the container.

Conveniently, in the second case referred to above, the apparatus includes worm-collection means in the form of an endless belt moving within the space embraced by the conveyor surface e.g. running from the inlet end of the apparatus at which the worm-containing medium is supplied to the conveyor-surface to the outlet end of the apparatus at which the segrated worms, and usually also the worm-depleted medium, are discharged.

Conveniently, when a worm-collection belt is used as above described, then a static or, preferably, a rearwardly-brushing rotary brush is provided to lightly sweep the upper surface of the worm-collection belt so as to remove loose medium therefrom without at the same time dislodging the worms.

The worms are removed from the conveyor at the outlet end of the apparatus by any convenient means e.g. by a brush or water jet etc. acting on the surface of the conveyor.

Conveniently, the conveyor surface is supplied with the worm-containing medium by a loading belt moving within the space embraced by the surface.

In a preferred embodiment, the supply means and the worm-collection means are provided by one and the same belt, the worm-containing medium being displaced from said belt on to the spike-carrying surface before the upper surface of said belt reaches the worm-collection region of the apparatus.

Conveniently, the worm-containing medium is displaced from said belt as above described by a slanted deflector blade or brush engaging the upper surface of said belt near the inlet end of the apparatus.

Throughout this application, the term "spike" should be taken to mean any rod-like element, whether tapering or not, e.g. having a circumference of not more than about 6 to 7 mm.

Although the spikes may extend substantially perpendicularly to the conveyor surface, in currently preferred embodiments they have their tips trailing their root portions e.g. by being inclined at up to 10 to said conveyor surface.

Also, although the spikes are conveniently substantially straight, it is also possible to have them slightly curved e.g. so as once again to have their tips trailing their root portions which are substantially perpendicular to said conveyor surface.

Further, as already indicated, the spikes may be of substantially constant cross-section or they may taper towards or at their tip portions.

The cross-sectional shape of the spikes is conveniently circular but spikes of other smooth or polygonal cross-sectional shape may be used instead if desired e.g. spikes of elliptical, rectangular, square or hexagonal cross-section.

In all the cases described above using an internally-spiked conveyor surface, the apparatus is preferably so arranged as to promote an overall flow of the medium from one end of the apparatus to the other.

Thus where a cylindrical drum or a belt is used as the rotary member, its rotation axis is preferably tilted so that medium left behind by the conveyor surface as on rotation it becomes more and more steep is continually collected in the lower part of the conveyor where it works its way towards the lower end of the conveyor for discharge e.g. into an appropriate receptacle.

Where, on the other hand, the rotary member is provided by an open spike-carrying framework of squirrel-cage form, the longitudinal axis of the cooperating container is preferably tilted to provide the overall flow of material through the apparatus.

Obviously in this case, the rotation axis of the framework will be similarly inclined so as in all places to provide the desired co-operation between the rotary member and the supply means. In this latter case, or if the container is not tilted as above described, the desired overall movement of the medium through the apparatus may also be encouraged (or wholly provided) by the use of appropriately angled deflector plates secured to the framework in addition to the spikes.

Where instead, the rotary member is provided by an open spike-carrying framework of helical form, then the helical spike-carrying framework will act somewhat in the manner of an auger so as on rotation to induce movement of the medium along the length of the apparatus. Thus in this case, slop ing of the container and/or the provision of angled deflector plates on the framework, though permis sible, will not generally be required.

The invention also includes an apparatus accord ing to the present invention when adapted for the harvesting of worms direct from a bed of the worm-containing medium.

Embodiments of the invention will now be de scribed, by way of example only, with reference to the accompanying diagrammatic drawings in which Figure 1 is a schematic side view of a first em bodiment including only one worm-separating conveyor; Figure 2 is a schematic side view of a second embodiment including two such conveyors; Figure 3 shows a plan view of a first design of worm-segregating apparatus in accordance with the present invention; Figure 4 shows an end view of the apparatus of Figure 3; Figures 5 and 6 show perspective views of alter native designs of worm-segregating apparatus in accordance with the invention; Figure 7 shows an end view of a modification of the rotors used in the first and second embodi ments; and Figures 8 and 9 show diagrammatic side views of two embodiments adapted for the harvesting of worms direct from a bed of the worm-containing medium.

Thus referring first to Figure 1 of the drawings, an apparatus 10 for separating worms from a worm-containing medium comprises an endless belt conveyor 12 fed with worm rich waste from a hopper 14 by a vibrating feed plate 16 inclined downwardly towards the worm-bearing run of the conveyor. The drive means (not shown) for vibrating the plate 16 is preferably adjustable to provide a means of controlling the feed to the conveyor.

Reference numeral 18 indicates an anti-spill plate and numerals 20, 21 indicate receptacles for the worm-free waste and worms respectively.

The conveyor itself comprises a one metre wide spike-bearing belt passing around end rollers 23, 24 of which the top support roller 23 is driven and the bottom roller 24 is free-running.

Powered elliptical agitators 26 run against the back of the return run of the belt to ensure the release of the worms into the receptacle 21 as will hereinafter be described. A third elliptical agitator 28 acts less severely on the upper part of the worm-bearing run to encourage the release of any material adhering either to the flat surface of the conveyor belt or to the spikes 30.

These latter typically take the form of circular cross-section rods of 80 mm length and 2 mm diameter spaced apart from one another on 50 mm centres, e.g. in a square grid-like formation.

Typically, the width of the spike-bearing belt is 1 metre and the centre-to-centre separation of rollers 23, 24 is about 2 meters. Although any conventional material or materials may be used for the belt, the belt should preferably have a surface which will not easily allow the medium from hopper 14 to adhere to it. Thus, typically, the belt would be woven cotton, for example.

In operation of the apparatus 10, the conveyor 12 is driven in the sense shown with a surface speed of about 0.2 metres per second, say, and the feed plate 16 is vibrated to supply a steady stream of worm-rich waste from the hopper 14 to the upper run of the conveyor 12.

As the worm-bearing run of the conveyor moves upwardly from the anti-spill plate 18, the worm free waste will tend to run down between the spikes 30 and into the receptacle 20 leaving uncontaminated worms draped over the spikes from whence they will drop by gravity into the receptacle 21 during the return run of the conveyor.

As already described, agitator 28 will encourage the release from the belt portion of the conveyor or any medium not already discharged into the receptacle 20.

Worms contaminated or heavily contaminated with the medium from hopper 14 will also tend to be discharged with the bulk of the worm-free medium into the receptacle 20.

Turning now to Figure 2, this shows a modification of the first embodiment in which the conveyor 12 discharges its output onto the upwardly moving run of a second conveyor 32. This provides for a further separation to take place, the worms being discharged by conveyor 32 into the second receptacle 212 as before while any medium initially present with the worms when they leave the conveyor 12 rolls or slides down the conveyor 32 into the first receptacle 20.

The conveyor 32 may be of any suitable form and could, for example, be of the same spiked-belt configuration as the conveyor 12. However, the drawing shows a preferred version in which the rubber-faced conveyor 32 and the associated co-rotating brush 33, agitator 34 and scraper plate 35 take the form described in the co-pending Patent Application 8334551 referred to earlier. A typical surface speed for conveyor 32 might be 025 metres per second.

Referring now to Figures 3 and 4 of the drawings, an apparatus 110 for separating worms from a worm-containing medium comprises a cylindrical drum 112 carrying a plurality of radially inwardlyprojecting spikes 14.

Extending from end to end of the drum 112 is a worm-collection belt 116 running from an input (material-loading)section 118 to an output (worm discharge) section 120.

Typically, the diameter of the drum is about 0.8 metres, its length is about 2.5 metres and there are 1700 spikes arranged in forty rows, each spike biting of about 6 cm length and 0.2 cm diameter. It will be appreciated therefore that in practice there are far more spikes than the drawings suggest. In general the more spikes that are present, the more effective is the machine. The upper limit on the number of spikes is that if they are closer together in any direction than, say 50 mm, there exists the danger that clods of waste may bridge between adjacent spikes and be lifted up on to belt 116.

The rotation axis of the drum 112 inclines downwardly at about 2" from the input end of the appa ratus to its output end. Conveniently, the upper worm-collection surface of the belt 116 is similarly inclined.

Reference numeral 122 indicates a deflector blade or brush slanted to deflect material from the surface of belt 116 on to the inner surface of the drum 112.

A static or rearwardly-sweeping rotary brush 124 at the outlet end of belt 116 removes from the belt any medium falling on the belt from the upper region of the drum. The likelihood of medium reach ing the upper surface of the belt 116 in this way may be significantly reduced by vibrating the drum 112 so as to dislodge loose material from the conveyor surface of the drum before it ever comes over belt 116.

By having the brush 124 only lightly sweep the upper surface of the belt, there is substantially no danger of dislodging from the belt worms which have dropped on to the belt from the spikes.

Respective receptacles (not shown) for the segregated worms and the worm-depleted medium are provided at the outlet end of the apparatus.

In operation, the belt 116 is driven at, say, 0.25 metres per second, the drum is rotated at 6 to 7 r.p.m. and the worm-containing medium is loaded on to input section 118 of belt 116 from a hopper (not shown). With a drum inclination of about 2", a typical throughput for such an apparatus might be about 10 to 15 litres of worm-containing medium per minute.

Figure 5 shows an alternative embodiment of the invention in which the drum 112 and the loading section 118 of the belt 116 are replaced by an open framework 125 rotating within a part-cylindrical container 126 for the worm-containing medium.

The advantage of this arrangement over that of the first embodiment is that the absence of rotation of the medium-containing vessel will cause less motion to be imparted to the bulk of the material so that any tendency to balling displayed by wet material will be correspondingly less.

Once again, appropriate receptacles (not shown) may be provided for collection of the segregated worms and the worm-depleted medium.

The embodiment of Figure 6 differs from that of Figure 5 in having the open framework (128) of helical form. Optionally, three or four thin strengthening ribs (not shown) may extend longitudinally along the length of the helix to increase the rigidity of the framework.

Apart from the auger-like action already referred to in general terms above, the rotary member of Figure 6 has the further advantage that the turns of the framework helix present no substantial medium-lifting surface as they emerge from the container 126 so that the amount of contaminant reaching the worm-collecting belt 116 from the framework helix is very low. To maintain this advantage, when longitudinal strengthening ribs are provided to give the helix additional rigidity, the number and size of these ribs is kept to a minimum.

Figure 7 is a schematic end view of a drum-type or open framework rotary member for use in any of the last three embodiments above described in which, in accordance with a preferred feature, the spikes 114 are rearwardly inclined e.g. at up to 10 , so as to have their tips trailing their root portions when the rotary member rotates. The first advantage of this modification is that medium is less likely to become trapped between the root portions of the spikes and the adjacent spike-carrying surface because the rearward slope of the spikes results in an obtuse leading angle there rather than a right angle. This reduces the likelihood of material being inadvertently discharged on to the collector belt from the upper regions of the drum or framework.The second advantage is that the spikes 114 become inverted that much earlier thereby advancing the moment at which the worms will begin to slip down the spikes. This results in at least some of the worms being discharged from the spikes before the spikes reach the highest point of their travel thereby increasing the range of spike positions at which discharge can occur so as to allow the full width of the worm-collection belt to be utilized.

It is understood that the overall dimensions of the rotary worm-segregating members of Figures 5, 6 and 7 and the number, size and density of the spikes 114 are, in each case, intended to be substantially the same as was described with reference to the embodiment illustrated in Figures 3 and 4 of the drawings. In the embodiment of Figure 6, the helical framework will typically be constructed from a 10 mm diameter circular-section bar wound into a 40 to 50 turn helix, say, with a loop-to-loop clearance of about 20, 30 or 40 mm.

It should also be understood that features and modifications described in respect of any one em bodiment may also be incorporated in any other embodiment unless it is clearly inappropriate to do so. For example, the rearwardly inclined spikes of the drum-based embodiments may also be incorporated in the belt-based embodiments of Figures 1 and 2 if desired. The same is also true of other features having application in more than one embodiment.

Separation of worms from waste would normally be described out at a central plant, the separator being static and fed from a stockpile of the wormcontaining medium. However in the case of a large centralised vermicomposting enterprise, it may be desirable to have continuous harvesting of a small percentage of worms direct from the bed.

In this case, temperatures in the upper layers of the bed rise due to heat generated in microbial degradation of the waste and the separator is designed to move through these top worm-rich layers extracting worms as it moves. It would be convenient, for example, for the separator to be gantry-based, running on rails on either side of the bed, and the above-described separator designs and their variations could readily be modified for use on the bed in this way e.g. by omitting the feed devices 14, 16, 18 from the embodiment of Figures 1 and 2 and then gantry-mounting the machine over the bed so that it was able to comb through the top (say 50 mm) layers of the bed.

This arrangement is shown diagrammatically in Figure 8. In operation, waste lifted with the worms and separated from them would fall back on to the bed (130). As the machine advances along the bed, hopper 21 would be filled with the harvested worms.

The rotary co-axial conveyor separators of Figures 3, 4 and 5 could also be adapted for on-bed use by having the open cage machine depicted in Figure 5 (less trough 126) gantry-based and spanning the worm bed as shown diagrammatically in Figure 9. In operation, the rotating cage would advance sideways through the top bed layers and worms would be collected in a hopper at the end of the conveyor 116.

Claims (35)

1. An apparatus for separating worms from a medium containing the worms comprising an endless spike-carrying conveyor surface for the medium and/or worms and drive means for moving the surface over an endless path in which firstly the surface is or becomes sufficiently steep for at least the bulk of the medium to be left behind the worms become draped over the spikes and secondly in which the spikes thereafter become increasingly inverted until, gravity causes the worms to slide off the spikes for collection beneath the spikes when so inverted.

2. An apparatus as claimed in Claim 1 in which the conveyor surface is provided by an externally spiked belt or drum member.

3. An apparatus as claimed in Claim 2 comprising worm collection means in the form of a receptacle or a receptacle preceded by a second wormseparating apparatus.

4. An apparatus as claimed in Claim 2 or Claim 3 comprising supply means in the form of a vibrating plate inclined downwardly towards said inclined run of the conveyor.

5. An apparatus as claimed in Claim 1 in which the conveyor surface is provided by an internally spiked belt or drum member.

6. An apparatus as claimed in Claim 5 in which the conveyor surface is provided by the belt and this latter is supported on rollers or the like support means engaging the conveyor surface between the spikes.

7. An apparatus as claimed in Claim 5 in which the conveyor surface is provided by the drum member and the latter takes the form of an open spike-conveying framework of squirrel cage or helical form.

8. An apparatus as claimed in Claim 7 in which the drum member is of helical form and comprising supply means in the form of a cylindrical or part-cylindrical container embracing or at least in part embracing the drum member so that, on rotation of the drum member, the spikes will sweep through the medium-containing space of the container.

9. An apparatus as claimed in any of Claims 5 to 8 comprising worm-collection means in the form of an endless belt moving within the space embraced by the conveyor surface.

10. An apparatus as claimed in Claim 9 in which a static or rearwardly-brushing rotary brush is provided to lightly sweep the upper surface of the worm-collection belt so as to remove loose medium therefrom without at the same time dislodging the worms.

11. An apparatus as claimed in any of Claims 5 to 10 in which the worms are removed from the conveyor at the outlet end of the apparatus by a brush or water jet etc. acting on the surface of the conveyor.

12. An apparatus as claimed in any of Claims 5 to 11 in which the conveyor surface is supplied with the worm-containing medium by a loading belt moving within the space embraced by the surface.

13. An apparatus as claimed in Claim 12 in which the supply means and the worm-collection means are provided by one and the same belt, the worm-containing medium being displaced from said belt on to the spike-carrying surface before the upper surface of said belt reaches the wormcollection region of the apparatus.

14. An apparatus as claimed in Claim 13 in which the worm-containing medium is displaced from said belt by a slanted deflector blade or brush engaging the upper surface of said belt near the inlet end of the apparatus.

15. An apparatus as claimed in any preceding claim in which the circumference of each said spike is not more than about 6 to 7 mm.

16. An apparatus as claimed in any preceding claim in which the spikes extend substantially perpendicularly to said conveyor surface.

17. An apparatus as claimed in any of Claims 1 to 15 in which the spikes have their tips trailing their root portions.

18. An apparatus as claimed in Claim 17 in which the spikes incline rearwardly at up to 10 to said conveyor surface.

19. An apparatus as claimed in any preceding claim in which the spikes are substantially straight.

20. An apparatus as claimed in Claim 17 or Claim 18 in which the spikes are slightly curved so as to have their free end portions inclined and their root portions substantially perpendicular to said conveyor surface.

21. An apparatus as claimed in any preceding claim in which the spikes are of substantially constant cross-section or taper towards or at their tip portions.

22. An apparatus as claimed in any preceding claim in which the cross-sectional shape of the spikes is circular or of other smooth of polygonal cross-sectional shape.

23. An apparatus as claimed in any preceding claim in which the apparatus is so arranged as to promote an overall flow of the medium from one end of the apparatus to the other.

24. An apparatus as claimed in Claim 23 in which the conveyor surface is provided by the internally spiked drum member and the rotation axis of the drum member is tilted so that medium left behind by the conveyor surface as on rotation it becomes more and more steep is continually collected in the lower part of the drum member where it works its way towards the lower end of the drum member for discharge there.

25. An apparatus as claimed in Claim 23 when including the limitations of Claim 8 in which the longitudinal axis of the container is tilted to provide the overall flow of material through the apparatus.

26. An apparatus as claimed in Claim 23 or Claim 24 when each includes the limitations of Claim 8 or as claimed in Claim 25 in which the desired overall movement of the medium through the apparatus is provided or encouraged by the use of appropriately angled deflector plates secured to the framework in addition to the spikes.

27. An apparatus substantially as hereinbefore described with reference to and/or as illustrated in Figure 1 of the accompanying drawings.

28. An apparatus substantially as herein before described with reference to and/or as illustrated in Figure 2 of the accompanying drawings.

29. An apparatus substantially as hereinbefore described with reference to and/or as illustrated in Figures 3 and 4 of the accompanying drawings.

30. An apparatus substantially as hereinbefore described with reference to and/or as illustrated in Figure 5 of the accompanyiang drawings.

31. An apparatus substantially as hereinbefore described with reference to and/or as illustrated in Figure 6 of the accompanying drawings.

32. An apparatus as claimed in any of Claims 27 to 31 when modified substantially as hereinbefore described with reference to and/or as illustrated in Figure 7 of the accompanying drawings.

33. An apparatus as claimed in any preceding claim adapted for the harvesting of worms direct from a bed of the worm-containing medium.

34. An apparatus as claimed in Claim 33 substantially as hereinbefore described with reference to, and/or as illustrated in, Figure 8 of the accompanying drawings.

35. An apparatus as claimed in Claim 33 substantially as herein before described with reference to, and/or as illustrated in, Figure 9 of the accompanying drawings.