AU644418B2 - Fertiliser composition - Google Patents

Description

164441 COMMONWEALTH OF AUSTRALIA Patents Act 1952 Name of Applicant(s): Address of Applicant(s): GROW FORCE AUSTRALIA LTD 1808 IPSWICH ROAD ROCKLEA QLD 4106 o (0 0Q ,000 0 0 0 00*0y .D0 t* *40 Address for Service: CULLEN CO., Patent Trade Mark Attorneys, 240 Queen Street, Brisbane, Qld. 4000, Australia.

0 0 04 0* I COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: FERTILISER COMPOSITION *011 I00I The following statement is a full description of the invention including the best method of performing it known to us: 2 THIS INVENTION is directed to a method for preparing a fertiliser composition containing one or more additives and to a fertiliser composition containing one or more additives.

In particular, the invention is directed to a method for preparing a fertiliser composition having a substantially uniform distribution of one or more additives and to a composition containing the same.

0o Fertilisers are often manufactured and sold n o i incorporating one or more additives such as trace elements, 0 soil conditioning agents and the like.

It is important that the one or more additives are uniformly distributed relative to the main body of the fertiliser so that upon application, an even distribution of 15 fertiliser and additives is applied to crops, soil and the oco C. 0 like.

It is known to dry blend a fertiliser or mixture of fertilisers with one or more trace elements in an attempt to obtain a uniform distribution of the trace elements within the main body of the fertilisers. Trace elements are only required in very small amounts and to obtain a uniform distribution of trace elements into the main body of the fertilisers, the trace elements are usually added as a powder to the main body of the much larger granulated fertilisers.

A disadvantage with such a method is that although the initial dry blending may result in a uniform distribution of the trace elements within the main body of the fertiliser, segregation of the trace elements occurs upon prolonged 1, I pJ i L 3 standing and handling of the fertiliser mix. Thus, application of the fertiliser mix results in an irregular application of trace elements to the target area.

In order to overcome the difficulties of segregation between the trace element particles and the fertiliser granules, it is known to increase the particle size of the trace element material to approximately equal that of the particle size of the fertiliser. The much larger than usual particle size of the trace elements and the low concentration of the trace elements in the fertiliser mix results in the mean distance between the trace elements in the mix being large. Thus, upon application of such a mix to a target area, the number of trace elements particles per unit area is low and results in an irregular application of trace element material to the soil or crops.

It is an object of the invention to provide a fertiliser composition and a method for preparing a fertiliser composition which may substantially overcome the abovementioned disadvantages or provide the public with a useful choice.

In one form the invention resides in a method for preparing a fertiliser composition comprising mixing together fertiliser granules with one or more additives, said additives having a particle size of between 0.01 100 microns, whereby the additives are caused to adhere to said fertiliser granules with a substantially uniform distribution over said granules, and 'chen coating the fertiliser granules with a binder consisting of a nonaqueous liquid polymer mixture.

In another form, the invention resides in a fertiliser composition prepared by the foregoing method.

.L i i 4 The fertiliser composition comprises granules of one or more fertilisers and one or more additives having a particle size of between 0.01 100 microns, and a binder consisting of a non-aqueous liquid polymer mixture.

The one or more fertilisers may comprise phosphatic fertilisers, nitrogenous fertilisers, inorganic fertilisers and organic fertilisers. Preferred fertilisers include diammonium phosphate (DAP), monoammonium phosphate (MAP), urea, ammonium sulphate, muriate of potash and superphosphate. The fertiliser may be present singularly or as a mixture of fertilisers.

The fertiliser usually has a granular or prilled structure and an average particle size range of Preferably the fertiliser comprises particles of uniform size.

The one or more additives may include nutrients, pesticides, nematicides, fungicides and/or other soil conditioning agents. The additives may be present singularly or in combination.

The nutrients may comprise one or more trace elements. The trace elements may be selected from copper, zinc, iron, boron, molybdenum, magnesium, and manganese. The trace elements may be in the form of oxides, sulphates or chelates.

The one or more additives preferably have a particle size of 40 microns or less. Particles of this size may be provided by passing the additives through a 400 mesh sieve.

The one or more additives may comprise between 0.01 -1 20% by weight of the fertiliser composition and preferably comprise between 0.1 10% by weight depending on the type of additive.

The binder may oe polymeric. The binder may be water soluble and preferably is readily solubilized upon contact with moisture. The binder may comprise an ethylenically unsaturated polymer. The ethylenically unsaturated polymer may comprise an acrylate which may be Q *0 carboxylated. The carboxyl groups may be partially neutralised. The neutralising groups may comprise an amine moiety. The amine moiety may comprise a monoethanolamine.

The polymeric binder may be in the form of an emulsion or a solution. Preferably, the polymeric binder is in solution as a monoethanolamine salt of a carboxylate acrylic copolymer. The copolymer may have a solids content of in solution.

The solution is preferably sufficiently volatile to allow ready flashing off in the mixing stage. A M£pint of between 50 100°C is suitable and a preferred i-a is between 55 70°C. The solution suitably comprises hydrocarbons such as petroleum hydrocarbons which may contain aromatics. A particularly preferred solution is 80% petroleum hydrocarbons 20% aromatics having a boiling range of 180 2880C.

The one or more additives may be added to the fertiliser by batch mixing or by adding intermittent amounts of the additives to the fertiliser while the fertiliser is being mixed. It is less preferred that the additives and the 6 fertiliser are batch mixed as this mays cause a dust problem.

The binder may be added to the fertiliser mixture after initial mixing of the fertiliser and the additives. The binder may be added to the fertiliser and additive mix as a solution. The solution may be added in bulk to the fertiliser/additive mix followed by mixing to distribute the binder over the fertiliser/additive particles. Alternatively, the binder solution can be sprayed over a mixture of the fertiliser/additives. The spraying action may be continuous or intermittent.

The mixture of the fertilisers/additives and addition of the binder may be carried out at ambient temperature and in any conventional or convenient type of mixing apparatus. The mixing action is preferably carried out at a sub- tmospheric pressure to minimise dust emission and to facilitate "flashing off" of excess polymer solution.

Preferably, air is continuously drawn through the mixing apparatus and the cure to assist in carrying away the volatiles. The air ma. be heated.

The invention will be better understood by reference to the following description of one preferred embodiment thereof and as illustrated in the accompanying drawings in which Figure 1 is a plan view of an apparatus for forming the fertiliser composition.

Figure 2 is a side view of Figure 1.

Figure 3 is a plan view of a further apparatus for forming the composition.

ii 7 Figure 4 is a side view of Figure 3.

As shown in Figure 1 and 2, a granulated fertiliser or blend of fertilisers (500kg'" is added to the top of a cone shaped continuous mixing chamber The chamber is provided with a planetary auger (not shown) which rotates at approximately 100 revs per minute. The granulated fertiliser is added to the chamber by a feeding auger 11. Twenty-five Kg of a desired trace element or mixture of trace elements are fed through feeding conduit 12 into a trace element mixing drum 13 which is mounted for rotation about its horizontal axis. Once the trace element mixture has been sufficiently mixed, it is passed from drum 13 to conveyor 14 where it is passed to a weighing tower 15. Weighing tower 15 includes funnel 16 to funnel the trace element material passing along conveyor 14 to weighing container 17. In this manner, a correct amount of trace element mix can be weighed out. Weighing container 17 discharges the trace element mixture into feeding auger 18 which feeds the discharged trace element mixture to fertiliser feeding auger 11.

Feeding auger 18 feeds a trace element material into feeding auger 11 to allow some pre-mixing to occur Si prior to passing the fertiliser/trace element mixture into mixing chamber The trace element material has previously been passed through a 400 mesh screen to provide particles of microns or less.

The chamber continuously mixes the fertiliser and trace elements mixture and suitably has the capacity to hold 3 sl to 3.5 tonnes of materials. The chamber i' pressurised to sub-atmospheric pressure to minimise emission of the very fine particle size trace elements from the chamber.

As the fertiliser/trace element material is passed into the chamber from the feeding auger, it is sprayed by a polymeric binder. The sprayed fertiliser/trace element material is thereafter mixed in the chamber and passes out of a lower portion therefrom.

The polymeric binder is stored in tank 19 and is passed into chamber 10 through suitable conduit 20 by a metering pump 21.

Air is continuously passed through mixing chamber by a suitable pump (not shown) to facilitate flashing off of the polymer solvents.

The polymeric binder is GLASCOL LS2 sold by Allied Colloids General Industries Division. The polymeric binder has the following properties: Nature: Carboxylated acrylic co-polymer Form: Solution Viscosity: 1000 cps PH: Specific gravity: Solid content: 20% by weight Initial softening point: approx. 100°C Flash point: 6 1 0

C

The co-polymer is supplied as a 20% solution as the monoethanolamine salt.

Approximately 3.25 litres of the polymer binder is added for every 500kg of the fertiliser/trace element mixture.

After further mixing of the fertiliser/trace element mixture with the polymer solution, any remaining solution is "flashed off" to provide a fertiliser composition having a substantially uniform distribution of trace elements which are bound to the fertiliser by the polymer binder. While not wishing to be bound by theory, it appe c that the fine particle size of the additives results in a static interreaction between the additives and the fertiliser. Due to 1 i0 this inter-reaction, the additives are uniformly distributed over each fertiliser particle. The additives are thereafter bonded to the fertiliser particle by the binder.

In this manner, there is provided a uniform coating of desired additives around every particle of fertiliser and, which due to the binder, do not segregate or settle upon transportation or prolonged storage.

In an alternative method, it is possible to pre-mix the trace element material with the polymer binder and spray this mixture over the granulated fertiliser as it passes from ,2C the feeding auger into the mixing chamber.

Application of this fertiliser mix will result in an even distribution of fertiliser and additive particles to a target area.

Furthermore, by having the binder readily water soluble, the binder will dissipate upon contacting moisture in the soil to release the fertiliser and additives to the soil.

Initial tests indicate that additives having a particle size over 100 microns do not tend to be efficiently distributed around particles of fertiliser which is probably due to their increased size overcoming any weak static interreaction. Additive particles having a size of less than 0.001 microns are generally less useful due to their dust problems and difficulty of handling.

Figures 3 and 4 show a simpler hand fed fixing system to prepare the desired compositions in smaller volumes.

In this version, fertiliser in granules or powder is $q transported along conveyor 25 and into a ribbon mixer 26.

1O Pre-weighed trace elements and a desired polymeric binder is hand fed into the ribbon mixer 26 and after sufficient mixing and flashing off of excess solvent, the finished product is passed through outlet 27 and onto a second conveyor 26 which the finished product to a bagging facility (not shown).

While the invention has been described with reference to trace elements as the additives, it should be appreciated that additives such as pesticides, nematicides and fungicides could also equally be used. Such an application would reduce costly and dangerous application of pesticides and fungicides by spraying and would ensure an even distribution of the pesticide and fungicide to the target area.

Various other changes and modifications may be made to the embodiment described without departing from the spirit and scope of the invention.

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Claims (16)

1. A method for preparing a fertiliser composition comprising mixing together fertiliser granules with one or more additives, said additives having a particle size of between 0.01 100 microns, the fertiliser granules being larger than the additives, whereby the additives are caused to adhere to said fertiliser granules with a substantially uniform distribution over said granules, and then coating the fertiliser granules with a binder consisting of a non-aqueous but at least partially water soluble liquid polymer mixture.

2. The method as claimed in claim 1, wherein the one or more fertilisers are selected from the group consisting of phosphatic fertilisers, nitrogenous fertilisers, inorganic fertilisers and organic fertilisers.

3. The method as claimed in claim 1 or claim 2, wherein said granules are of a uniform size.

4. The method as claimed in any one of the preceding claims, wherein said one or more additives are selected from the group consisting of nutrients, pesticides, nematicides, fungicides and soil conditioning agents. The method as claimed in claim 4, wherein the one or more additives are selected from trace elements.

6. The method as claimed in clp-m 5, wherein said trace elements are selected from copper, zinci, iron, boron, molybdenum, magnesium and manganese.

7. The method as claimed in claim 6, whereiln the trace elements are in the form of oxides, sulphates or olelates.

8. The method as claimed in any one of the preceding cli-ms, wherein the one or more additives have a particle size of between 0.1 40 mjcrons. S9. The rsthod as claimed in any one of the preceding claims, wherein the one or more additives comprise between 0.1 20% by weigh'- of the fertiliser composition. 12 The method as claimed in Claim 9, wherein the one or additives comprise between 0.1 10% by weight of the fertiliser composition.

11. The method as claimed in any one of the preceding claims wherein the binder comprises an ethylenically unsaturated polymer.

12. The method as claimed in Claim 11 wherein the ethylenically unsaturated polymer includes acrylate groups.

13. The method as claimed in Claim 12 wherein the binder comprises a monoethanolamine salt carboxylate acrylic copolymer.

14. The method as claimed in any one of the preceding claims, wherein the binder is in the form of an emulsion or a solution with the emulsion or solution having a solids content of between 10 The method as claimed in Claim 14, wherein the emulsion or solution has a flash point of between 50 1000C.

16. The method as claimed in Claim 15, wherein the flash point is between 55 70 0 C.

17. The method as claimed in any one of Claims 14 to 16, wherein the emulsion or solution comprises liquid hydrocarbons.

18. The method as claimed in Claim 17, wherein liquid hydrocarbons comprise 80% petroleum hydrocarbons and 20% aromatics.

19. The meLtod as claimed in any one of the preceding claims wherein said coating of binder is by spraying over or into the mixture of fertilisers and additives. A fertiliser composition prepared by the method of any one of the preceding claims.

21. The method as claimed in Claim 1 substantially as hereinbefore described. DATED THIS FIFTH DAY OF JULY 1993 GROW FORCE AUSTRALIA LIMITED AiLL, by their Patent Attorneys CULLEN CO