GB2288132A

GB2288132A - Method and apparatus for making mulch or compost

Info

Publication number: GB2288132A
Application number: GB9406902A
Authority: GB
Inventors: Ronald Joseph Mahoney
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-04-07
Filing date: 1994-04-07
Publication date: 1995-10-11
Anticipated expiration: 2014-04-07
Also published as: GB2288132B; GB9406902D0

Abstract

A shredder for shredding compatible organic waste comprises a knife 4 for shredding the waste, and a device for recirculating the waste past the knife until the particle size of the waste is less than 9mm<2>. The shredder may include a screen 6 to prevent the discharge of oversized particles of waste. The shredder may include two sets of knives and screens placed in series in order to reduce the organic waste in two stages. <IMAGE>

Description

METHOD AND APPARATUS FOR MAKING MULCH OR COMPOST This invention relates to a method and apparatus for making mulch or compost.

Organic refuse has of course long been rotted to form mulches and composts. One problem with conventional rotting techniques is the time required for rotting. The delay can result in a large pile of decaying material.

A known shredder for garden waste comprises a rotary blade. Waste is fed into the rotating blade and drops into a receiver.

According to the invention there is provided a shredder comprising a cavity with an inlet, an outlet and a rotary blade contained in the cavity. The outlet is provided with a mesh such that material of a larger size than the mesh aperture is retained within the cavity.

In a preferred embodiment material exiting the cavity is introduced into a second cavity provided with a second blade and a second mesh with apertures smaller than the first apertures.

Embodiments of the invention will be described by reference to the accompanying figures of which: Figure 1 is a cross-section of a prior art device; Figure 2 is a cross-section of a first embodiment of the invention; and Figure 3 is a cross-section of a second embodiment of the invention.

The prior art device comprises a motor 1 which drives a pair of knives 2 carried on a rotor arm. The knives 2 rotate about a generally vertical axis A.

Material is fed into the device through an inlet 3 in the top. The material passes through the device and impinges on the knives which chop it. The chopped material then falls into a receiver B.

In accordance with the invention a knife for chopping debris is provided. Preferably the knife is a rotary knife such as a pair of knife blades 4 carried on a rotor arm. An inlet 5 for introducing material into a chamber of the device is provided. The chamber also has an exit (6). In a convenient embodiment of the invention the exit is in the form of a mesh or sieve placed at the base of the chamber. A mesh size of about 12 mm2 may be used. The mesh prevents material exiting the device until it is reduced in size. Oversize material should be recirculated past the blades for reduction in size. A very convenient way of achieving this is by making the volume of the chamber swept by the blades a large proportion of the total volume of the chamber. Material contained in the chamber is thus continually moved and thereby circulated past the blades.

A greater degree of control of compaction can be obtained by making the chamber volume variable. One way of doing this is by making the lid of the chamber movable relative to the chamber. In use the lid can thus rest on the top of the debris and compress it. As waste is chopped and exits the device the lid descends reduces the chamber volume. If desired the descent can be powered or can take place under gravity.

The chopped material exiting the chamber may be used as described hereinafter. In other embodiments of the invention the material exiting the chamber is chopped again in a further chamber. In the embodiment of Figure 4 the exit mesh of the first chamber is the inlet to the second chamber. The second chamber is provided with a knife and an exit. The exit allows finely divided material to exit the chamber. Insufficiently divided material is recirculated past the knife. A convenient way of achieving this by combination of a small chamber and an exit mesh. The mesh of the second sieve may be smaller say for example 8mm2 than the first sieve if desired. In practice it may well be found that adequate results are obtained by using the same mesh size.

If desired one or more further knives and chambers can be provided.

Material shredded in prior art devices is generally allowed to rot for some considerable time. If desired an accelerator can be mixed with the shredded material but rotting may still take a considerable time.

The material exiting the device of the invention can be rotted in this way if wished. The small particle size of the product results in rapid rotting even in the absence of accelerator.

Another way of handling the product is to compost it for a short period, say two or three weeks. At the end of this time the product resembles peat in appearance and has little odour. The product in this form is exceptionally useful as a mulch. The product continues to decay in situ. Several advantages accrue from this.

First water is generated in the rotting process and water loving plants mulched with the product are thus less dependent on extraneous water supply. Secondly the decay generates heat and this produces a degree of frost resistance and may accelerate growth. Thirdly the decay can provide controller release of nutrients into the growth media. The product may therefore have particular utility for packaging plants for transport in view of the water generating properties of the product.

It has been surprisingly found that plants mulched in this way are not particularly susceptible to dampingoff.

The chopped material can be added to the soil and used directly as a mulch or soil conditioner or stored typically in bags for use in the spring as a peat substitute.

In principle a very wide range of organic matter can be treated in accordance with the invention. Fallendeciduous leaves are of particular use but other readily chopped material may be used advantageously.

Claims

CLAIMS:

1. A shredder for shredding compatible organic waste, the shredder comprising: a knife for shredding the waste, and means for recirculating the waste past the knife until the particle size of the waste is less than 9mum2.

2. A shredder as claimed in claim 1 wherein the knife is situated within a chamber having an inlet and an outlet the outlet having a screen to prevent discharge of waste having a particle size of less than 9mm2.

3. A shredder as claimed in claim 2 wherein the knife is a rotary knife comprising a plurality of blades mounted on a rotor arm.

4. A shredder as claimed in claim 2 or claim 3 wherein having a further chamber with an inlet, knife and screened outlet downstream of the first chamber.

5. A shredder as claimed in claim 4 wherein the knives are mounted on a common drive shaft.

6. A shredder substantially as described herein by reference to Figure 2 or Figure 3.

7. A method of shredding compostable organic matter comprising the steps of i cutting the waste with a knife, ii recirculating the waste past the knife until the particle size of the waste is less than 9mm2.

8. A method as claimed in claim 7 wherein the knife is situated within a chamber having an inlet and an outlet, the outlet having a screen to prevent discharge of waste having a particle size of less than 9mm2.

9. A method as claimed in claim 8 wherein the discharged material is charged into a further chamber having a knife and a screened outlet.

10. A method as claimed in any one of the preceding claims wherein the organic material consists essentially of fallen deciduous leaves.

11. A method of shredding substantially as described herein by reference to Figure 2 or Figure 3.

12. A method of preparing a mulch comprising the steps of shredding organic as claimed in any one of claims 7 to 11 and composting the shredded waste.

13. A mulch obtained by the process of claim 12.