NZ221117A - Fertiliser compositions possessing a moisture content of between 0%-30% and method of preparation - Google Patents

Description

22111 7 PATENTS FORM NO: 5 Fee No. 4: $170.00 THE PATENTS ACT 1953 COMPLETE SPECIFICATION After Provisional No: 221117 Dated: 17 July 1987 * TITLE: "FERTILISERS" We JACOBUS JOHANNES MARIA VOOREND and LEONARDUS JOHANNES VOOREND, both New Zealand citizens of Avifauna, Onions Road, R.D. 8, Hamilton, NEW ZEALAND hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: 221117 This invention relates to fertilisers, more especially poultry based fertilisers whose NPKS levels have been supplemented by one or more additional components.

Poultry manure has long been used as a fertiliser. It is often supplied in a dried form as this not only renders the manure more readily utilisable, the decreased moisture content inhibits bacterial processes that may otherwise occur during storage and additionally decreases the weight of the product which is a transport consideration. The product is also more pleasant for the end user. Due to the high moisture content of unprocessed poultry manure, which may be as high as between 65 and 85%, problems are often encountered with conventional drying processors which often suffer blockages or clogging when processing manure mixtures with moisture contents greater than 50%.

To counter this problem, known methods of processing manures include mixing dried manure with undried manure to produce a mixture with a moisture content that is more acceptable to the processing dryer. New Zealand Patent No. 151582 discusses such a method. However, the remixing of already dried manure with undried manure adds additional steps to what should otherwise be a simple process, the additional steps add expense to the drying process in terms of the additional energy consumed. The greater expense is also reflected in the decreased output rate as compared to a drying process which passes the manyre through a dryer only once.

The present invention seeks to provide a method of drying poultry manure or other manure that addresses the above problems and also provides a fertiliser resulting from same.

While the invention relates primarily to poultry manure, application to other manures is possible, "other manure" defined as hereinafter referring to manures based on human or animal excrement, or compost.

According to one aspect of the present invention there is provided a method of producing a fertiliser composition comprising the steps of: mixing poultry or other manure with one or more additional components, said additional components being inorganic fertiliser products as defined within this specification; 2 2 2 1117 feeding the aforementioned mixture into an extrusion dryer; passing the mixture through the extrusion dryer and subjecting the mixture as it passes therethrough to conditions which provide that the mixture as it is expelled from said extrusion dryer possesses a moisture content of between 0% and 30%; S- cooling the mixture after it exits the dryer.

According to another aspect of the present invention there is provided a method of producing a fertiliser composition substantially as described above but also including one or more steps wherein each of said steps comprises the addition of one or more dust inhibiting agents.

According to a further aspect of the present invention there is provided a fertiliser composition as prepared by a method substantially as described above.

Whilst poultry manure alone is a useful fertiliser, it generally beneficial to fortify same to increase the levels of the NPKS elements. Typically the poultry manure (dried) was found to possess nutrient levels of approximately 3.5% nitrogen, 3.0% phosporous and 1.4% potassium. In order to decrease the bulk of a fertiliser to be applied to the soil, fortification of the fertiliser mixture to levels approaching 6% of each of the aforementioned elements was considered desirable.

Often poultry and other manures are fortified through the addition of organic components such as Blood and Bone though as the NPKS content of most organic components are similar to the original manure, the desired levels can either not be achieved or are uneconomical to use as a fortifying component.

It is therefore necessary to add inorganic components to achieve the desired NPKS levels. We define inorganic, where used throughout the specification, as being related to those compounds or substances derived from processes other than biological or bio-chemical processes and which are often characterised by having chemical formulae from which carbon to carbon bonds are absent. Commonly this class of compounds includes sulphate, phosphate, nitrate and chloride salts of the elements potassium, 221117 sodium, calcium, magnesium and also often the ammonium cation. Also included within this class are synthetically made compounds or substances, an example of such being urea which is also produced by biological processes. We note that commercial forms of the inorganic components may have present contaminants which are not inorganic as defined, but acceptable.

Several commercially available inorganic fertiliser components are used in practice. Common nitrogen sources are urea with 46% nitrogen, sulphate of amonia with 21% nitrogen and 24% sulphur (which has the added advantage of being a source of sulphur), potassium nitrate with 13% nitrogen and 38% potassium (contributing both nitrogen and potassium), diammonium phosphate with 18% nitrogen and 20% phosporous, which is again a dual nutrient source.

It was found that the moisture content of the final mixture was a consideration in selecting nitrogen sources. Poultry manure is mildly alkaline which allows it to react with ammonium compounds to liberate ammonia gas. The reaction generally requires water as a transport media so that mixtures having high moisture contents exhibit this effect more noticably.

Three general solutions to inhibit this unwanted reaction are available. One is to avoid the use of such ammonium compounds, though this precludes the use of many low priced effective nitrogen sources. Secondly, the moisture content of the fertiliser mixture could be maintained at a sufficiently low level to retard or reduce the rate of reaction. It was found that mixtures with moisture contents of less than 14% were sufficiently stable under most circumstances with 10% or less being preferred. The third solution is to alter the pH of the fertiliser mixture so that it is either non-alkaline or mildly acidic. This would reduce to an insignificant amount the liberation of ammonia gas, such changes in pH being accomplished through the addition of a component that was acidic in nature or through the use of buffers. The more desirable additive is commercially available superphosphate which, not only is acidic in its character, but also a good source of phosphorus. 221117 Phosphorus sources include phosphate rocks with 13% phosphorus; commercial superphosphate with 9% phosphorus and 11% sulphur; diammonium phosphate with 18% nitrogen and 20% phosphorus and triple superphosphate with 20% phosphorus and 2% sulphur. The diammonium phosphate is a rich source of both nitrogen and phosphate and is preferred in some formulations of the product. Rock phosphate is a very slow release form of phosphorus whilst superphosphate has a relatively low nutrient level. Triple superphosphate is another preferred source of plant available phosphorus.

Potassium sources include muriate of potash (potassium chloride) with 50% potassium, potassium sulphate with 40% potassium and 17% sulphur and potassium nitrate which has been previously mentioned.

Other nutrients may be added. Sulphur may be provided through the addition of some of the components previously mentioned or could be added in the form of finely ground sulphur. Commercially available formulations, such as Sulfix with a 12-13% sulphur content, are also suitable. The magnesium content is typically low in poultry manure though this may be countered through the addition of magnesium oxide or Epsom salts (magnesium sulphate). Boron may also be required as a trace element, a suitable source being a waste material such as coal fly ash (which is rich in boron).

Further, to reduce the problem of reaction amongst the components (such as the liberation of ammonia gas from ammonium compounds) it is advisable to choose components that are not hygroscopic or deliquescent in nature. Urea, diammonium phosphate, and muriate of potash are all hygroscopic and should either be avoided or used when they do not form a substantial portion of the total mixture.

A preferred fertiliser composition or mixture has nutrient levels or approximately nitrogen 6%, phosphorus 5-6%, potassium 6%, sulphur 5% and magnesium 2%. The following formulation has been used to produce a mixture with these nutrient levels, the percentages listed being weight percentages: 221117 50% manure % sulphate of ammonia 16% triple super 11% muriate of potash 3% magnesium oxide.

This represents a reasonably cost effective formulation, at the date of filing this application, though fluctuating market rates for the individual components will dietermine the cost feasibility of various formulations. The level of hygroscopic components (muriate of potash) has been reduced to 11%. Subsequent laboratory testing has shown that this component causes the moisture content of the above mixture to equilibrate to 14% if left exposed to air. This level is acceptable, a moisture content of the final product in the range between 10 and 15% being most desirable. The same laboratory testing shows that a small amount of plant available nitrogen is lost over time in a sample with a 30% moisture content. Samples with less than 15% moisture content showed negligible nitrogen loss and were considered to be stable.

An alternative formulation which is also cost effective, at the date of filing this applicaton, is the following (percentages are by weight): 13% sulphate of ammonia 7% commercial sulphur preparations such as "Sulfix" with a sulphur content of approximately 12-15% 16% mono-ammonium phosphate 11% muriate of potash 3% Magnesium containing preparation or compound 50% manure A blend of poultry manure and urea in proportions of 90%: 10% respectively, showed increased nitrogen loss through liberation of ammonia even when the moisture content was as low as 20%. This is due to the alkaline nature of the poultry manure and methods of reducing this loss have been previously mentioned. 22 1117 The blending of components to produce a viable fertiliser composition are open to considerable variation. A typical range of components would be as follows: %-90% of poultry or other manure 0%-60% of an additional nitrogen source 0%-50% of an additional phosphorus source 0%-50% of an additional potassium source 0%-20% of an additional nutrient source.

The nitrogen source may be defined as any substance or component capable of supplying or releasing plant available nitrogen, said nitrogen source also being an inorganic substance as previously defined.

The phosphorus source may be defined as any compound or substance capable of supplying or releasing plant available phosporous, said phosphrus source also being an inorganic substance as previously defined.

The potassium source may be defined as any substance or component capable of supplying or releasing plant available potassium, said potassium source also being an inorganic substance as previously defined.

The additional nutrient source may be defined as any inorganic compound or substance able to supply other plant available nutrients such as sulphur, boron, magnesium etc.

Once a formulation for a fertiliser mixture has been decided upon, the individual components may be combined and blended. Typically this involves their addition into a hopper wherein a mixing means, such as a rotating screw or auger, blends the components to a substantially homogeneous mixture. This may be performed as a batch process such as where the components are blended prior to the stage of the process involving drying. Alternatively components could be continually added in approximately correct proportions so that the whole process may be operated as a flow process. In this case it may be necessary to introduce a more elaborate feed system to maintain the components at the correct desired ratios. 221117 To the mixture can be added a dust inhibiting agent to reduce the release of dust into the surrounding environment or to settle dust formed. Normally the moisture content of the manure will keep dust levels to an acceptable limit however, if necessary the dust inhibitor may be added at this stage. Oil based agents such as vegetable or light hydraulic oils were found to be very satisfactory for this purpose though heavier waxy substances are also suitable. These are typically added in low proportion, typically 0.1%-3%, though this depends largely on the moisture content of the mixture and how prone the individual components are to dust formation.

After the blending of the components, the resulting mixture is fed into an extrusion dryer. Transferring the mixture from the blending hopper into a feed hopper creates a buffer region such that a correct mixture can be continuously fed into the extrusion dryer whilst a new batch of components are blended. The contents of the feed hopper may be agitated to prevent the clogging of the entry neck into the extrusion dryer. Again a variety of mixing or agitating means may be used, a rotating blade or auger assembly being possiblities.

The blended mixture is fed into an extrusion dryer. Extrusion dryers are typically used in food technology related areas and are used for such purposes as drying byproducts from the dairy industry, by-products from the processing of meat and fish or the drying of protein and/or grain sources to produce animal and stock feed. The extrusion dryer produces a drying effect through pressure and friction of the material within the device. It has an advantage over many conventional dryers in that it will operate satisfactorily with mixtures of components possessing a high moisture content. Until now, no applications of such a dryer have been made to fertiliser production or other applications outside the food technology related areas for which it was specifically designed. The effects of passing manures combined with inorganic components had not been previously attempted and questions such as the problems to be encountered were unanswered. It was also unknown as to how the unique drying technique of the extrusion dryer would effect the final nutrient levels in the product. 22111 An extrusion drier, such as an INSTAPRO MODEL 2000, has been found to be amenable to the drying of manure based blended fertiliser mixes with little or no modification. Care should be taken that excessively large particles such as lumps of rock phosphate or stones and gravel do not find their way into the machinery, though the occasional particle does not appear to damage the machine. It has also been found that the addition of the mentioned inorganic compounds and substances in the proportions previously mentioned do not affect the operation or drying ability of the machine under normal conditions. The presence of other extraneous matter such as egg shells or feathers do not effect the process though the quantity of shell fragments should be kept to a minimum. It has also been found that whole or portioned carcasses of poultry may also be fed through the machine however these should only constitute a minor proportion of the total mixture. Higher proportions would be acceptable only for very short runs or durations. Use of a means of increasing the moisture content of the mixture as it is processed within the drier is advisable when low percentages of manure are present. A water injection system is one solution to this problem.

With regard to the addition of inorganic substances, it is preferable that in the majority of instances manure constitutes at least 50% of the total mixture. It may be necessary to regularly check the machine for wear when using high proportions of inorganic substances for extended periods as the dryer was originally intended for processing moist organic substances.

The drying parameters on an extrusion dryer such as the INSTAPRO MODEL 2000 extrusion dryer may be readily altered to vary such factors as the average time spent by material whilst passing through the device and also the average temperature reached within. These factors are largely determined by the moisture content of the ingoing mixture in relation to the desired moisture content of the mixture as it exits the dryer (typically 15%-20%). The operating guide lines and manual for the extrusion dryer used should be consulted for guidance in this respect. 221117 Increasing the time spent within the unit can be useful for producing a sterilised fertiliser product. This helps to prevent further bacterial action on the fertiliser product which could possibly lead to alteration of the nutrient levels or ratios in same. Sterilising the mixture also reduces the risk of transmission of disease through the handling and use of the fertiliser product.

After the mixture exits the extrusion dryer, it should be cooled before further handling or packaging. Preferably the mixture is passed through a rotary dryer with a forced induction system. The forced induction serves to further dry the mixture whilst it is cooling, reducing the moisture content to a value of typically between 10% and 15%. We note that the parameters of the drying and cooling processes may be altered to achieve alternative final moisture ratios.

After the mixture has been cooled it can be then packaged ready for transportation and sale. We envisage that other cooling methods may be used and it may be suitable to merely allow the mixture to cool naturally. The use of a rotary or tumble dryer makes it possible to add at this stage a dust inhibiting agent. Some agents may not survive processing through an extrusion dryer, for instance light vegetable oils. It is therefore preferable to incorporate them as a dust inhibitor or dust settling agent at a stage after the extrusion drying process. This could be either prior to cooling, during cooling or subsequent to cooling. The same agents or inhibitors as previously mentioned could be added. It is also possible that such agents are added both before and after the drying stage as the need may be.

A variety of oils or even waxes may be used as a dust inhibitor. Oils suitable for use include commercially available vegetable, mineral or synthetic oils intended for domestic, light industrial or farm use. This includes, for instance, cooking oils, engine oils, hydraulic and gear box/transmission oils. Waxes suitable for use include paraffin waxes and natural waxes (eg. bees wax, castor wax) and even animal and butter fats. There is no reason to suggest that any particular oil would be unsuitable for use as a dust inhibitor.

Aspects of the present invention will now be discussed by way of example only with reference to the accompanying drawing in which: Figure 1: is a schematic diagrammatic view of a preferred embodiment of apparatus for effecting a method for producing a fertiliser composition which comprises the steps of: mixing poultry or other manure with one or more additional components, said additional components being inorganic fertiliser products within the specification; 22 1117 feeding the aforementioned mixture into an extrusion dryer; passing the mixture through an extrusion dryer and subjecting the mixture as it passes therethrough to conditions which provide that the mixture as it is expelled from said extrusion dryer possesses a moisture content of between 0% and 30%; cooling the mixture after it exits the extrusion dryer.

Referring to Figure 1, the apparatus generally comprises the following: a receiving chamber or hopper, generally indicated by arrow 1; a mixing chamber orJnopper, generally indicated by arrow 2; a feed chamber or hopper, generally indicated by arrow 3; an extrusion dryer, generally indicated by arrow 4; a rotating drum cooler/dryer, generally indicated by arrow 5; a holding chamber or hopper, generally indicated by arrow 6; conveyance means 7 to transport the mixture between the aforementioned components.

In operation, the individual components of the fertiliser mixture are loaded into the receiving chamber 1. This item has a wide mouth to facilitate loading by mechanical shovel of individual components. The opening is also close to ground level and arranged so that components may also be readily added by hand.

A conveyance system, comprising a conveyor belt, transports the mixture of components from the bottom of the receiving chamber 1 into a mixing chamber 2. A rotating auger 8 mixes the components into an essentially homogeneous blend. The mixture, after blending, exits said mixing chamber 2 through an aperture at the bottom thereof, whereupon it is conveyed by conveyor belt 7 to the feed chamber 3.

The mixing chamber 2 can be configured as an essentially batch orientated process. To achieve this method of operation the conveyance means between the mixing chamber 2 and fed chamber 3 is only operated (preferably by operator or after a 221117 prescribed duration) after total blending of components within said mixing chamber 2 has been achieved. This method ensures a more consistent blended mixture than a method of operation configured as a flow process. When using the latter method care and attention must be taken that components are fed into the receiving chamber at a fairly constant rate and in the approximately correct desired proportions to achieve consistency in mixture. The fed chamber 3 serves as a buffer for in a batch orientated process, whereby a constant supply of blended mixture is ensured to the extrusion dryer 4 whilst the next batch of mixture is blended within chamber 2.

A rotating blade assembly 9 within the feed chamber 3 continuously agitates the mixture to prevent clogging within the substantially narrow neck 10 leading to the extrusion dryer 4. This is important for mixtures having relatively high moisture contents, such as generally used throughout the process.

The mixture is then fed into the extrusion dryer which through its process of drying expels a product of typically between 10 and 20% moisture content. If necessary water may be injected into the dryer through the water injection system 11 to increase the moisture content of the product as expelled from the dryer. The injection system can be further adapted to inject oil 12 which is used as a dust suppressing agent.

From the extrusion dryer 4 the mixture is fed into the rotating drum cooler/dryer 5. A forced induction system 13 forces air through the drum as it rotates. This not only serves to cool the product but also further reduces the moisture content to the desired level of between 10% and 15%.

After the dried mixture exits the rotating drum cooler/dryer 5 it is conveyed, again by conveyor 7, to the holding chamber 6. At this stage the process is essentially over and the dried mixture can be held within this chamber 6 until such time as it is ready for bagging into suitable containers 14. 22 111 No pulverising or comminuting stages are necessary, as the extrusion dryer 4 has the ability to reduce the particle size of many lumps of fragments. The average size of the particles as they leave the extrusion dryer are adjustable, being a parameter on many models which may be altered by the user. The method of achieving this depends on the exact model of an extrusion dryer and the operation manual should be consulted in this respect. We do note that the extrusion dryer was never intended to be a pulverising unit so consideration should be taken as to the form of the components added to the mixture. Large particles of rock phosphate could conceivably cause damage if they were added to the mixture, it being advisable to use granular forms of the additional components.

Typically, in use, a mixture comprising the following components are loaded into the receiving chamber 1 and blended in the mixing chamber 2: 500 kilograms poultry manure; 130 kilograms sulphate of ammonia; 160 kilograms mono-ammonium phosphate or other ammonium phosphates; 110 kilograms muriate of potash; 70 kilograms sulphur or commercially available sulphur containing preparation; 30 kilograms magnesium oxide; yielding a total of 1000 kilograms.

The product resulting from such a mixture is granular in form and not unpleasant to handle. There is little or no offensive smell in the product with a moisture content in the vicinity of 10% to 15%, which yields a substantially stable product when based on the preceding components.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions thereto may be made without departing from the spirit or scope thereof.

Claims (29)

221117 WHAT WF. CLAIMS IS:

1. A method of producing a fertiliser composition comprising the steps of: mixing poultry or other manure with one or more additional components, said additional components being inorganic fertiliser products as defined within the specification; feeding the aforementioned mixture into an extrusion dryer; passing the mixture through the extrusion dryer and subjecting the mixture as it passes therethrough to conditions which provide that the mixture as it is expelled from said extrusion dryer possesses a moisture content of between 0% and 30%, and cooling the mixture after it exits the extrusion dryer.

2. A method of producing a fertiliser composition comprising: the steps as claimed in claim 1; said method also including one or more steps wherein each of said steps comprises the addition of one or more dust inhibiting agents.

3. A method of producing a fertiliser composition as claimed in claim 2 wherein the further step of adding dust inhibiting agents occurs prior to or during the passing of the mixture through the extrusion dryer.

4. A method of producing a fertiliser composition as claimed in claim 2 wherein the further step of adding dust inhibiting agents occurs after the passing of the mixture through the extrusion dryer.

5. A method of producing a fertiliser composition as claimed in any one of claims 2 to 4 wherein an oil or wax is used as a dust inhibiting agent.

6. A method of producing a fertiliser composition as claimed in any one of the preceding claims wherein one or more of the additional components are chosen on the basis of their ability to effect the pH of the mixture.

7. A method of producing a fertiliser composition as claimed in any one of the preceding claims wherein one or more of the additional components are chosen on the basis of their ability to alter the NPKS ratio of the fertiliser composition. C1-- PA r. 221117

8. A method of producing a fertiliser composition as claimed in any one of the preceding claims wherein one or more of the additional components are chosen on the basis of their ability to increase any of the plant nutrient contents of the fertiliser composition.

9. A method of producing a fertiliser composition as claimed in any one of the preceding claims wherein one or more of the additional components are chosen on the basis of their stability with respect to decomposition of the fertiliser composition during storage.

10. A method of producing a fertiliser composition as claimed in any one of the preceding claims wherein the mixing of the manure with the additional components is effected by a rotating auger or screw blade within a hopper.

11. A method of producing a fertiliser composition as claimed in any one of the preceding claims wherein the mixture is agitated as it is fed into the extrusion dryer.

12. A method of producing a fertiliser composition as claimed in any one of the preceding claims wherein water is injected into the mixture as it passes through the extrusion dryer to increase the moisture content of the mixture such that it has a moisture content exceeding 0% and less than 30% as it exits said extrusion dryer.

13. A method of producing a fertiliser composition as claimed in any of the preceding claims wherein the conditions to which the mixture is subjected as it passes through the extrusion dryer are adjusted such that the mixture is sterilised after it has passed therethrough.

14. A method of producing a fertiliser composition as claimed in any one of the preceding claims wherein further moisture loss from the mixture by evaporation occurs during the cooling step.

15. A method of producing a fertiliser composition as claimed in any one of the preceding claims wherein the cooling step occurs by passing the mixture through a rotating drum assembly whilst an induction system directs air therethrough, moisture loss continuing whilst cooling of the mixture occurs.

16. A method of producing a fertiliser composition as claimed in any one of the preceding, claims wherein the mixing of the components is performed in batch lots to/mpvide a <-vv\ 15 221111? continuous supply to the feeding, drying and cooling steps which are carried out as an essentially continuous process.

A method of producing a fertiliser composition as claimed in any one of the preceding claims wherein all of the steps are performed as an essentially continuous process.

A method of producing a fertiliser composition substantially as herein described with reference to the accompanying drawing.

A fertiliser composition as prepared by a method as claimed in any one of claims 1 to 18.

A fertiliser composition as claimed in claim 19 wherein said fertiliser composition results from a predried mixture comprising {% by weight): 20% - 90% of poultry or other manure; 0% - 60% of an additional nitrogen source as defined within the specification; 0% - 50% of an additional phosphorus source as defined within the specification; 0% - 50% of an additional potassium source as defined within the specification; 0% - 20% of an additional nutrient source as defined within the specification; and wherein a mixture comprising the above components must total 100%.

A fertiliser composition as claimed in claim 20 wherein at least half of the additional nitrogen source is contributed by sulphate of ammonia.

A fertiliser composition as claimed in claim 20 wherein a least half of the additional phosphorus source is contributed by a commercial super phosphate preparation.

A fertiliser composition as claimed in claim 20 wherein at least half of the additional phosphorus source is contributed by Diammonium Phosphate.

A fertiliser composition as claimed in claim 20 wherein at least half of the additional potassium source is contributed by muriate of potash.

A fertiliser composition as claimed in claim 20 wherein at least half of the additional nutrient source is contributed by magnesium oxide.

A fertiliser composition as claimed in claim 23 wherein at least half of the additional nitrogen source is contributed by urea and wherein one or more of components are selected such that the resulting fertiliser composition is non^mficaline. is P vsoa«« 221117

27. A fertiliser composition as claimed in any one of claims 19 to 26 wherein the predried mixture consists substantially of the following components in the following proportions (% by weight): 50% of poultry or other manure; 13% of sulphate of ammonia; 16% of mono-ammonium phosphate or other ammonium phosphates; 11% of muriate of potash; 7% of sulphur or a commercially available sulphur containing preparation; 3% of magnesium oxide.

28. A fertiliser composition as claimed in any one of claims 19 to 27 wherein the NPKS contents in the final composition are substantially as follows (% by weight): Nitrogen 6%; Phosphorus 5%; Potassium 6%; Sulphur 5%.

29. A fertiliser composition prepared by a method substantially as herein described with reference to the accompanying drawing. ■TACOBIJS JOHANNES MARIA VOOREND and LEORNARDIJS JOHANNES VORREND by their Attorneys