GB2349638A

GB2349638A - Transportable composting cage

Info

Publication number: GB2349638A
Application number: GB9910456A
Authority: GB
Inventors: Kevin Michael Chandler; Alan Heyworth
Original assignee: TEG Environmental PLC
Current assignee: TEG Environmental PLC
Priority date: 1999-05-06
Filing date: 1999-05-06
Publication date: 2000-11-08
Anticipated expiration: 2019-05-06
Also published as: GB9910456D0; GB2349638B

Abstract

For reception of material to be composted, a mesh cage 20 is mounted inside a frame 10 of fixed dimensions, of a size which can be transported upon a vehicle. A mesh liner 30 is mounted inside the cage 20 so as to be displaceable upwardly to project beyond the top of the cage. This liner 30 is raised at the site where composting is to take place to allow for reception of sufficient volume and the necessary residence time. A conveyor 42 extends between the bottom of the cage 20 and the base 12 of the frame 10 to allow for collection of composted material. The bottom of the mesh cage 20 may be provided by a series of substantially parallel rotors (44, Figs. 2 and 4) which control the amount of material allowed to fall through onto the conveyor 42.

Description

TRANSPORTABLE COMPOSTING CAGE This invention concerns a container, referred to herein as a cage, for receiving and holding waste material, primarily of a biological nature, while it undergoes aerobic degradation to compost.

The process of composting is complex. Aerobic bacteria effect the breakdown of the biological material. Thus the material to be composted must be well aerated, not overcompacted, and preferably with a mixture of fine and coarse material. This limits the size of any composting container. If it is too large the material in the centre will not be sufficiently aerated and anaerobic processes will ensue, as well as overheating.

In providing a container suitable for a continuous composting process, i. e. with fresh material being added at the top and adequately degraded material removed from the bottom on a regular basis, such as weekly, or every few days, it is necessary to allow for a sufficient height of material to be retained. In this respect, the material is compacted and reduced in volume as it is degraded and moves downwards within the container, but it still requires a sufficient residence time, in the region of 7-21 days. Thus the container must be high enough to accommodate the amount of material which will be added during that period, to provide a suitable depth of regular compost yield at the bottom.

An object of the present invention is to provide a composting cage based on an outer frame of fixed dimensions, of a size which can be transportable upon a vehicle in the manner of a skip.

Such a cage, it is believed, would be extremely useful for dealing with waste material in parks and public gardens and other establishments that have a greater requirement for bulk composting than a domestic garden.

The present invention proposes a composting cage comprising a mesh cage mounted inside a frame, a conveyor extending between the bottom of the cage and the base of the frame, and a mesh liner mounted inside the cage so as to be displaceable upwardly to project beyond the top of the cage.

Thus, for the purposes of transportation of the cage to its site of operation, or between sites, the height is likely to be limited. For example, a maximum of 10ft (3m) is usual in the case of conventional skip transportation. The height of the mesh cage can be limited to this, and the liner will be in a low position, not projecting above the height of the cage, during transport. Then, on site, to allow adequate height for composting, as explained above, the liner can be raised to project above the cage. In this respect a height of 14ft (4.2m) is generally preferable, although in some cases a height of 12ft (3.6m) may be adequate.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a preferred embodiment of a transportable composting cage of the invention, the liner being shown in a raised position, ready for use of the cage; Figure 2 is an enlarged scale end view of the same cage from the right hand end in Figure 1, but with the mesh of the inner cage and liner omitted for ease of illustration; Figure 3 is a reduced scale side view of an individual rotor of the cage of Figures 1 and 2; Figure 4 is an end view of the rotor shown in Figure 3; and Figure 5 is an enlarged scale diagram showing operation of these rotors.

As illustrated, this preferred practical embodiment of the invention comprises an outer metal frame (10), a mesh cage (20) fixed just inside the frame (10), and a mesh liner (3) which is adjustably mounted inside the cage (20).

The outer frame (10) has a flat rectangular base (12) secured to a pair of elongate supports (14). This leaves a gap below the base (12) enabling the frame (10) to be lifted by tines or the like in a manner which is conventional in relation to the lifting of skips. Along each side of the base (12) there are a plurality of equidistantly spaced upright stanchions (16) of box section (hollow) extending to respective top frame members (17). The dimensions of the base (12) and the height of the stanchions (16) are the same as a conventional skip. Also at the front end of the frame (10), a hook (18) is provided, which is similar to a conventional skip hook. Thus the frame (10), and its contents, can be lifted onto a truck, and will fit thereon and can be transported in the same manner as a conventional skip.

At the front end of the frame (10), a cabinet (40) housing hydraulic motors and a drive mechanism are mounted. Immediately to the rear of the cabinet (4) and extending the remainder of the length of the frame is the mesh cage (20). This cage (20) comprises a plurality of upright box section stanchions (22), of equal number to those (16) making up the outer frame (10), and also extending to respective top frame members (23). Each stanchion (22) and top frame member (23) is mounted directly inside, i. e. in alignment with the corresponding stanchion (16) and top frame member (17) of the outer frame (10) by way of spacer elements (24), which may be welded or rivetted in position. Mesh (26) is fixed onto or between the stanchions (22) around all four sides of the cage to provide an enclosure for receiving material to be composted. However, around the lower margin of the cage (20) metal panels (28) replace the mesh (26).

The top of the cage (20) is at the same height as the top of the frame (10), which typically may be 10ft (3m). The bottom of the cage (20) is spaced above the flat metal base (12) of the frame (10).

Between the bottom of the cage (20) and the base of the frame (10), a conveyor (42) in the form of an endless belt is mounted.

As shown in Figure 2, the conveyor (42) extends the full width of the frame (10). As shown in Figure 1, the conveyor (42) projects beyond the rear of the frame (10). At the front, it passes into the cabinet (40), where it passes around a drive roller connected to and driven by the hydraulic drive mechanism.

The bottom of the cage (20) is formed by a plurality of longitudinally extending rotors (44), as shown in Figures 2 to 5.

Ten are used in this embodiment. Each rotor (44) comprises a hollow tube on to which two bars (46) are longitudinally mounted at diametrically opposed positions so as to provide a pair of opposed radial projections. In the rest position shown in Figures 2 and 4 alternative motors (44) are positioned with their bars (46) arranged in vertically opposed and horizontally opposed dispositions. The horizontally opposed bars (46) extend into close proximity to the adjacent rotors (44) and thereby close off the bottom of the cage (20) sufficiently to prevent much material falling therethrough. The rotors (44) are connected up to the hydraulic drive mechanism so as to be rotated simultaneously. When they are rotated, as the bars (46) move out of the horizontally opposed position, material in the lower margin of the cage (20) drops between the rotors (44) onto the conveyor (42).

Returning to consider Figures 1 and 2, the mesh liner (30) is formed in a similar way to the mesh cage (20) of plural upright stanchions (32) extending between top and bottom frame members (33,34), the outer stanchions (32) also being in alignment with the stanchions (16,22) and mesh (36) extending therebetween around all four sides. However, the liner (30) is open bottomed and is unsecured. It is a close sliding fit in the cage (20).

When in its lowest position (Figure 2) it does not project upwardly of the cage (20). However, it can be raised and retained at a higher position (Figure 1) projecting above the top of the cage (20) in which it is supported. Indeed, the liner (30) can be secured at different selected heights relative to the cage (20) since its securement is effected in a simple manner by bolts (not shown) inserted through apertures in the aligned stanchions (22) (32) of the cage and the liner respectively.

The composting cage is filled using any known type of telescopic loading shovel. This is not shown in the drawing.

In use, the cage will be transported to and positioned at a site of operation in the same manner as a skip, the liner (30), of course, being in its lowest position (Figure 2), during transport and unloading, as mentioned above. Once positioned on site, the liner (30) will be raised so that its top frame members (33) are at an appropriate height above the ground. This will probably be about 14ft (4.2m), as already mentioned. The interior of the cage (20) and liner (30) will then be loaded with a suitable mix of material to be composted, e. g. waste vegetation of various sorts and sizes, by means of the loading shovel. It is quite important that the material should be sprinkled into the top of the cage, and thus aerated, and also that the filling should be done so as to distribute the material evenly, i. e. so its top surface is substantially level.

A residence time of about 16 to 21 days is normal for a depth of composting material up to about 14ft (4.2m) from ground level.

During transport, unloading, and initial set up the rotors (44) and the conveyor (42) are not operated and the rotors (44) remain in the position shown in Figure 2, effectively closing off the bottom of the cage (20). Once the material in the bottom few inches is adequately degraded, after the aforesaid residence time, the rotors (44) and the conveyor (42) can be actuated, by switch means on the housing (40), so that the rotors undergo a fixed number of complete revolutions and allow the bottom few inches of composted material to fall through onto the conveyor (42) and be conveyed to the rear of the cage for collection.

The foregoing is illustrative and not limitative of the scope of the invention. Any variations in the detailed features of the design are possible within the scope of the invention.

Claims

CLAIMS 1. A composting cage comprising a mesh cage mounted inside a frame, a conveyor extending between the bottom of the cage and the base of the frame, and a mesh liner mounted inside the cage so as to be displaceable upwardly to project beyond the top of the cage.
2. A composting cage according to claim 1 wherein the bottom of the mesh cage is provided by a series of substantially parallel rotors having radial projections.
3. A composting cage according to claim 1 or claim 2 further including hydraulic drive means mounted within the frame for operating the conveyor and/or the rotors.
4. A composting cage according to claim 1,2 or 3 wherein the frame is provided with means enabling the cage to be lifted onto a vehicle for transportation.
5. A composting cage substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.