Production of Nutrient Material This invention relates to the production of particulate nutrient material, chiefly, but not exclusively, for use as fertiliser, as a soil condi¬ tioner, -or, in some cases, as an animal feedstock. The invention affords a means of utilising the high nutrient content of' an animal manure, particularly chicken manure, to provide an effective fertiliser or, in some cases, an animal feedstock base. The invention provides in one aspect a process for the production of nutrient material in pellet form, comprising the mixing of absorbent paper shreds or cellulose fibres impregnated with animal manure and the formation of the material into pellets. here the impregnating manure is chicken manure the impregnated paper shreds or fibres may be admixed with a superphosphate before pelleting to fix the nitrogen which would otherwise be released as ammonia.

A process according to one embodiment of the invention for the production of particulate nutrient material comprises:

(i) a mixing stage in which absorbent paper shreds impregnated with animal manure are mixed with a supherphosphate; (ii) a mincing stage in which the mixed material from stage (i) is extruded through a mincer and cut into compacted pellets, and

(iii) a comminution stage in which the pellets are broken up into particles. The mincing stage, which may be carried out using an industrial mincing unit or pelleting machine, entails extruding the material through orifices in a plate, accompanied by heating of the material frictionally. If it is desired to produce a nutrient material

OMPI /»* WIPO -

for use as a feedstuff base it is arranged that the material is heated frictionally in the mincing stage or pelleting machine to a sufficient temperature and for a sufficient time to at least partially sterilise the mixture extruded through the orifice plate. Sterilisation may alternatively be effected completely or partially by irradiation of the mixture, for example by ultra-violet or gamma radiation.

It has been found that an effective way of regulating the heating of the material extruded in the mincing stage is by control of the proportion of dry material in the mixture fed to the mincing apparatus or pelleting machine.

If the material is required in particulate rather than pelleted form comminution may be effected by feeding the pellets to a rotating vaned impeller, the pellets being broken up by the impeller to produce particles which may subsequently be aereated by passing them through a cyclone. The resulting particulate material is rich in nutrients derived from the manure content of the original mixture and is highly suitable as a fertiliser and soil conditioner. Moreover, since the manure in the final product is carried by comminuted particles of paper the material is dry and easy to handle, package and store. The particulate paper-based material is also relatively odour-free.

Also within the scope of the invention is a particulate nutrient material consisting of particles of absorbent paper or cellulose fibre impregnated with animal aure, preferably chicken manure having a controlled moisture content, preferably 12% moisture by weight. The material may also be impregnated with superphosphate and/or fishmeal, according to the intended use of the material and

the desired protein content. The absorbent paper base of the particulate material is ideally derived from newsprint, which is non-toxic, thermally insulating and highly absorbent, being derived from wood fibres. The invention further provides plant for the production of particulate nutrient material comprising mixing apparatus for mixing pieces of absorbent paper impregnated with animal manure, and extrusion or mincing apparatus for extruding the mixed material from, the mixing apparatus to form compacted pellets. The apparatus may optionally include a comminuting chamber into which the pellets are fed, the chamber housing a rotary impeller having vanes which break up the pellets into particles. The invention will be further described, merely by way of example, with reference to the accompanying purely diagrammatic drawings, in which:

Figure 1 illustrates schematically in elevation a plant for the production of particulate nutrient material according to one embodiment of the invention; Figure 2 is a diagrammatic plan view of the plant shown in Figure 1;

Figure 3 is a perspective view of one of the mixing containers used in the plant of Figures 1 and 2, and

Figure 4 is a diagrammatic perspective view of the vaned impeller used in the comminuting stage of the plant shown in Figures 1 and 2.

Referring first to Figures 1 and 2, the illustrated plant is intended for the production of nutrient particles for use as fertiliser starting from manure- impregnated shredded paper. The raw material for the process carried out by the plant is in this case obtained from hen batteries where shredded newsprint is used as a bedding material. When soiled the

O PI /», IPO _\

shredded newsprint is collected and will be impregnated with chicken manure.

The manure-impregnated shredded paper :is placed in a four-sided mixing chamber 1 of square cross section having a hinged lid 2. As the raw material is introduced into the chamber 1 an additive material is added. For example, the additive may comprise superphosphate in a proportion of 8-10% by weight, the superphosphate being added in stages during the filling of the chamber with soiled paper, to fix the nitrogen by forming ammonium phosphate, checking the release of ammonia gas. When the chamber is full the lid 2 is closed and locked.

Alternatively, or additionally, protein in the form of oil or fishmeal may be added, particularly where the material is intended for use as an animal feedstock. For example, herring meal may be added to form a mixture containing 50-60% by weight of animal manure and 50-40% by weight respectively of fishmeal.

The chamber 1 is provided on its internal surfaces with diagonally extending fins 3 upstanding at right angles to the internal surfaces of the chamber on each of the four longitudinal sides of the chamber 1, including the lid 2, which forms a fourth side of the chamber 1 when closed. A central longitudinal shaft 4 extends through the chamber 1 and is provided at opposite ends with respective trunnions 5 externally of the end faces of the chamber 1. The trunnions 5 are used for supporting the entire chamber 1 for rotation about the axis of the shaft 4, disposed horizontally. Thus the trunnions 5 may be lowered into U-shaped supports carried by fixed support arms 6 at opposite ends of the chamber 1, as shown diagrammatically in Figure 1, the chamber 1 being

OMPI ^~~

raised and lowered into the supports using a suitable lifting crane or truck (not shown) .

One or both of the trunnions 5 terminates in a square-section driving portion which is engageable in a cooperating slotted end of the drive shaft of an electric motor-reduction unit 7 (Figure 2) .

Mixing of the material in the chamber 1 is effected by rotating the chamber 1 through about 60 revolutions by means of the motor-reduction unit 7. The mixing of the material is promoted by the fins 3, and the resulting mixed material can then be discharged from the chamber 1 by opening the lid 2, allowing the material to fall into a chute 8.

The mixed raw material is' collected from the chute 8 by an elevating conveyor 9 which conveys the material to an industrial mincer unit 10 driven by a heavy duty electric motor (not shown) . The mincer unit 10 has a circular outlet duct 11 provided with a plate 12 formed with a number of outlet orifices 13 through which the minced material is extruded in operation-of the mincer unit 10.

The mincer unit 10 is modified in the plant of this invention by the addition to the outlet duct 11 of a rotary knife 14 which is rotated, conveniently- by a drive derived from the mincing unit 10, over the external surface of the orifice plate 12 to cut the extruded and compacted material into pellets which typically measure about 10 mm in length and have a diameter of approximately 8 mm. The compacted material extruded from the mincer unit 10 will be heated by the considerable friction generated in the mincing and extrusion process. The temperature may exceed 100 C, the actual temperature being controllable by adding controlled amounts of dry material, for example, dry shredded paper, to the

OMPI

/,. WIPO «

- 6 - mincer unit 10 .

The pellets of compacted minced material are conveyed on a further elevating conveyor 15 to a comminuting chamber 16 into which the pellets fall under gravity. The chamber 16 is in the form of a vertical cylinder in which a rotary vaned impeller 17 is mounted coaxially. The impeller 17 is driven by an electric motor 18 at a speed of, typically, 2500-3000 rp . In the illustrated embodiment the vaned impeller 17 has the construction illustrated in Figure 4, consisting of six identical radial vanes 19 disposed in planes intersecting the axis of rotation of the rotor 17 and interconnected at their radially outer ends by metal ties 20. The pellets fall into one half of the comminuting chamber 17, where they are broken up by the rapidly rotating vaned impeller 17, and expelled through a tangential outlet duct 21 leading into a cyclone separator 22. The purpose of the cyclone separator 22 in this plant is to effect aereation of the pellet fragments, the resulting substantially dry particles of paper impregnated with nutrient material falling to the bottom of the cyclone chamber 22 for collection by an elevating conveyor 23 which conveys the particles to a packing '.or bag-filling and sealing station (not shown) .

If the minced and extruded material is subjected to a sufficiently high temperature upon extrusion to sterilise the material, the resulting particulate nutrient material may be used as a base for animal feed, for exampel as a base for the feed used by ruminanats, as pet focr or as a base for fish feed in fish farming. When used for feedstock the material may include further additives such as

GIΛTI

- 1 - flavouring constituents.

If the material is required in pelleted form the comminuting stage 16 would of course be omitted, and the extruded pellets would be conveyed over a - cooling-conveyor. The moisture content of the pellets is preferably controlled by regulating the extrusion process, as described, and in the cooling of the extruded pellets, which is effected by drawing air through the pellets on a conveyor, in a known manner. For packing in plastic bags the pelleted material should preferably have a moisutre content of 12% by weight.