CA1170071B - Drivable fertilizer spikes - Google Patents

Abstract

Abstract A hard, rigid fertilizer product compacted by briquetting and having a shape, mechanical strength and an impact resis-tance which adapts it to be hammered while unsupported into the ground without significant shattering and having a sub-stantially homogeneous composition consisting essentially of from 85% to 95% by weight substantially non-fibrous NPK fer-tilizer source materials bonded together by from 15% to 5%
by weight of a substantially water insoluble cured thermo-setting resinous binder based on the dry weight of the mix-ture.

Description

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~C~;GROt~ D OF TY.._ l~VEN'rION
Field Of The Invention .. . .
This invention relates to the art of making a fertilizer stick or spike which can be driven into the ground for the purpose of providing plant nutrients to trees, bushes and the like.

DESCRIPTION OF THE PRIOR ART
,, The Gessler Patent No. 3,057,713 dated October 9, 1962 discloses a fertilizer stick or spike of the type intended to have a mechanical strength and impact resistance of such high order as will enable it to be driven into hard ground with a steel-headed hammer for the purpose of fertilizing trees ana other like growths. Gessler's product consists essentially of (1) NPX source materials, including phosphoric acid, and (2) asbestos fiber. In the process of making the Gessler spike, the phosphoric acid reacts with the asbestos to produce a spike characterized by a relatively porous friable core surrounded by a non-porous non~friable shell. Ho~ever, the Gessler product is not always drivable, not consistent in quality and nOt invariably shatter-proof.
Other prior disclosures of the patent art include:
the soil treating cartridge of Van ~ahres, Patent No.
1,971,390; the fertilizing stick of Antrim, Patent No.

2,032,608; the fertilizing pill, pellet, stick, etc. of Jones, Patent No. 2,117,808; and the fertilizing cylinder of Martin et al, Patent No. 2,341,800. None of the foregoin9 prior art products can be rated as the equivalent of drivable spikes.

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obiect ~ tion The principal objects of the present invention are:
tl) to provide an uncured or "sreen" fertilizer spike, which c~n be made of adequate N~K source materials and a resinous bonding material, all of wnich are relatively plentiful, inexpensive, readily mixab7e together and easily briquetted or otherwise compressed into the for~ of a "green" spike, (2) to provide a green spi'~e which has a highly satisfact:ory green strength and which can be cured at room temperatures in a relatively short time; and (3) to provide a cured fertilizer spike, which can be produced and shippsd at a satisfactory cost, which has a good shelf life, which is not easily broken but, on the contrary, is so hard and sturdy that it can always be driven into reasonably hard ground without shattering or otherwise incurring appreciable damage, and which, in use, provides adequate fertili~er ingredients characterized by high fertili~er values ar.d solubility such that it yields all of its fertilizer values evenly and at slow desired rates over its useful life which preferably endures for at least one year.
Statement of the Inve _ on I have found that substantially all of the foregoing objectives can be achieved by mixing granular NPK source materials with a relatively small quantity of ~ resinous binder, for e~ample, an uncured granular thermosetting bir.der, such as urea-formaldehyde, compressing ~he mi~ture into the form of a sreen spi'~e and then curing the spike to convert the binder into a relatively insoluhle infusible aminoplastic St..ucture.

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BRIEE' DESCRlPTION OP T~E DR/~ ING
The single figure in the ~rawing is a flow diagram illustrating the process by which drivable spikes are made in accord2nce with the present invention and capped.

DESCRIPTION O~ rHE P~F~RRED E~5~0DIME~T
The presently preferred embodiment of the invention comprises a drivable spike, which contains 16.0 units of Nitroyen, 8.0 units of P2O5 and 8.0 units of K2O, and which is produced by curing a green spike, that is obtained by processlng the following formulation, viz:
Ingredients % Nu-trients Pounds A. ~ertilizer - 20 Mesh 1. N - Ammonium Sulfate (21-0-0)55.0 2. N - Urea-Porm such 2s DuPont's "Uramite"; Borden's "38"; or Hercules' "Nitro-form"*(38-0-0) 10.8

3. N,P2O - Diamrnonium Phosphata(18-46-0) 20.4

4. R2O - Potassium Chloride (0-0-62) 15.6 B. Supplernents 20 5. Micronutrients typified by frit-ted trace elements (F.T.E.) such as those made by E`erro Corp.~0-0-0) 2.20 6. Pigments such as the yellow and blue dyes made oy DuPont (0-0-0) 0,12 C. Resinous Binder - 200 Mesh 7. Urea-Formaldehyde, such as Monsanto Co.'s "U~-71"* ~0-0-0) 10.0 D. Moisture 8. H2O (0-0-0)0.0 lt7 *Trademarks ~ , ~ ~7~
Since the flow diagram illustra,ed in the drawing is more or less selr-ex21anator~, i' should su,fice to say that the above-stated formulation is processed into a final product spike by feeding t~e main fer,ilizer ingre-dients Al-4 and the supplement ingredi2nts B 5-o into a mi~er within which they are blended into a homogeneous mass as they flow therethrough. The binder ing~ecient C 7 (and the water ingredient C 8 when desired) may be fed into the mixer at any suitable point, the drawing showing them fed after the other insredients have progressed through a portion of the mi~ing operation.
From the mixer, the homogeneous mixture is passed into a briquetter which compresses a measured amount of it into one solid "green" spike, one end of which preLerably is blunt and the other pointed. This green spike then under-goes curing which may extend over a one day period at room temperature. The curing temperature may be elevated to decrease the curing time. However cured, the resulting ?roduct is a hard rigid drivable spike having a mechanical strength and an impact resistance of such high order as will enable it to be driven into reasonably hard ground with a steel-headed hammer without appreciable damage and preferably without any damage visible to the eye.
This drivable spike may have its blunt end dipped into a resinous cap-forming solution which will harden into a cap having sufficient impact resistance to withstand repeated blows or a steel-headed hammer when the capped spike is driven into hard ground. The cap thus contributes ~dditional impact resistance to the final product. If desired, a removable and reusable cap may be employed for ~ ~7(~(3~
single use or reneated use purposes.
There is nothing particularly critical about the fertilizer ingredients employed or the sources from which they are derived. The above-stated amounts of NPK ingredients mav be varied to change the 16:8:8 percentages to other useful percentages, such as 8:4:4,

5:5:5, 15:5:5, etc., which may be selected in order to meet particular needs or pur?oses. The higher concen-trations of nutrients are preferred, if only to minimize the number of spikes re~uired per tree, for example.
Likewise, selected amounts of other well known NPK
source materials may be substituted in whole or in part for those mentioned above, as for e~amp;e:
N - Urea 46-0-0 ~monium Nitrate NH4NO3 35-0-0 Mono Ammonium Phosphate 13-52-0 P - Mono Ammonium Phosphate 13-52-0 Triple Super Phosphate 0-46-0 Normal Super Phosphate 0-21-0 20~ - Potassium Sulphate ~2SO4 0-0-48 Secondary nutrients such as calcium, magnesium and sulphur, which are variously used by various plants in relatively large amounts, may be added, if deemed desirable or necessary but they usually are satisfactorily available in the soil. The micronutrients used are, of course, selected by the formulator to provide trace elements in the varieties and quantities desired. The materials selected may include one or more well known sources of iron, copper, manganese, barium, zinc and molybdenum.

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The dye supplement contributes nothins more than a desired color characteristic of the s~ike.
While the resinous binder is a urea-formaldehyde compound, it is intended to form a relatively insoluble structure; hence, it is not intended to, or selected for its ability to, provide a significant nitrogen nutrient contribution. The amount or binder used should be no more than is necessary to provide the requisite mechanical strength. The "UF-71" binder preferred has a urea-for-malcehyde ratio ranging from about 1.00 over 1.38 to about 1.00 over 1.80.
With a thermosetting resinous binder, the same asor equivalent to i'UF-71", a properly prepared mixture of 7 to 10% binder and 93 to 90~ of NPK containing no more than S.0~ free moisture, can be formed into a s?i~e of hignly satisfactory green strength via molding or briquetting under pressure or extruding. The addition of water to dry ingredients may be minimized by preheating the NP~/binder mixture to a temperature which rluidizes the binder and accelerates its tendency to cure. Where the "U~-71" binder is employed, this temperature may be around 180 F.
With a free moisture content of 2.0 to 5.0~ in the ~ material flowing to the briquetting unit, a subsequent water-evaporation step is not required. The spikes thus produced are readily released from the forming tools. Each spike emerges from both the mixing and forming equipment so cleanly that it~ poses no problem of clean-up. It will cure satisfactorily in one day exposure to an atmosphere of 70 F. and 60.0~ relative humidity. It goes without saying that this ~uring time can be reduced with the use 7~'~37~

of external heat such as oven, radiant or dielectric heat. The atmospheric curing of binders, typified by "UF-71"~ is promoted by (1) a free moisture content in the ranse of 2.0 to 5.0~, (2) a slight drGp in p~, which is effected by certain acid-forning components in the NPK
fraction, (3~ the addition of small quan.ities of a catalyst, such as ammonium chloride, and (4) the frictional heat manifested in forming a spike under pressure.
Some water shou]d be present in the materials used 10 to for;n the green spike in order to obtain a consistently good strong atmospherically-cured product. The primary fertili~er ingredients and the binder ingredients in the ?referred composition above set forth are hygroscopic. As a consequence, when exposed to humid weather conditions, they may absorb enough water from the atmosphere to insure the initial production of a curable spike of good green strength. If the dry materials ti.e. binder and nutrients) become notably desiccated, supplemental water should be added during the mixing operation to insure effective bonding.
In any such case, a water addition, ranging in weight from 1-1/2 to 2-1/2 percent of the weight of the material fed into the briquetter, is recommended.
While I prefer to briquet or mold the granular NPK
fertilizer material under pressure into the form of an elongate spike, it ~Jill be understood that any other means of compressing it into spiXe shape may be employed including extrusion. While I also prefer the use of a granular resinous bonding material incorporated in or mixed with the fertilizer mix before the spike-forming operation is per-fonned, it will be understood that I may use a resinous , (3~ ,71 -~ liquid bonding material in a manner insuring a satis-factory cisposition of the bonding liquid ?referably throughout the mass of the spike and the retention by the spi'ce of a sufficient but relatively sma]l quantity of the bonding a~ent, say between 5 to 15~ by weight. I
have ,ound that, when a liquid binder is used, the quality of the resulting spikes can be somewhat i,mproved i' such binder is uniformly distributed over the surface o the dry fertilizer particles through the agency of a suitable operation such as a mulling operation. However, many liquid binders have these undesirable characteristics, viz they contain either water or some other solvent which must be evaporated; and they polymerize only at an elevated temperature.
While I prefer fertilizer and binder ingredients of 20 and 200 mesh respectively, this is only a preference and not an essential characteristic of the present invention.
Where granular materials are employed, the mesh can be determined by the formulator.

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Claims (21)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A hard, rigid fertilizer product compacted by briquetting and having a shape, mechanical strength and an impact resistance which adapts it to be hammered into the ground without significant shattering and having a composition consisting essentially of a mixture of substantially non-fibrous NPK fertilizer source material bonded together by a cured thermosetting resinous binder.

2. A hard, rigid fertilizer product compacted by briquetting and having a shape, mechanical strength and an impact resistance which adapts it to be hammered while unsupported into the ground without significant shattering and having a substantially homogeneous composition consisting essentially of from 85% to 95% by weight substantially non-fibrous NPK fertilizer source materials bonded together by from 15% to 5% by weight of a substantially water insoluble cured thermosetting resinous binder based on the dry weight of the mixture.

3. A hard, rigid fertilizer briquette having a shape, mechanical strength and an impact resistance which adapts it to be hammered while unsupported into the ground without significant shattering and having a substantially homogeneous composition consisting essentially of 90% to 93% by weight of substantially non-fibrous NPK fertilizer source materials bound together by 7% to 10%, based on dry weight of the mixture, of a substantially water insoluble cured thermosetting urea-formaldehyde resin prepared from formaldehyde and urea in a ratio of from about 1.38 to about 1.8 formaldehyde to 1 urea.

4. A hard, rigid fertilizer product compacted by briquetting a mixture of granular NPK fertilizer source materials coated with an uncured thermosetting resin into a briquette having a mechanical strength, impact resistance and shape including a pointed end and a blunt end which adapt it to be hammered while unsupported into the ground without significant shattering and having a substan-tially homogeneous composition consisting essentially of granular fertilizer source materials bonded together by a substantially water insoluble binder formed by curing of the said thermosetting resin, said composition being devoid of fibrous materials and said binder providing the aforesaid mechanical strength and impact resistance and said product having a resinous cap on the blunt end.

5. A fertilizer briquette made by compressing at a pressure capable of forming, without the need for additional heat, a mixture of granular NPK source material and an uncured thermosetting resinous binder, a green briquette and by then allowing the binder therein to completely cure until mechanical strength and impact resistance permit said briquette to be hammered into the ground without significant shattering.

6. A fertilizer briquette made by compressing in a briquetter at a pressure capable of forming, without the need for additional heat, a mixture of granular NPK source material and an uncured urea-formaldehyde resinous binder to form a green briquette and then allowing the binder in said briquette to completely cure so that mechanical strength and impact resistance of the briquette is sufficient to permit it to be hammered into the ground without significant shattering.

7. A method for making a fertilizer briquette adapted to be hammered into the groundwithout significant shattering thereof which comprises:
preparing a mixture of granular NPK fertilizer source material and an uncured thermosetting resinous binder;
compacting the mixture in a die to a shape which adapts it to be hammered into the ground and to a green strength which permits it to be handled without substantial crumbling; and allowing the resinous binder to cure to form a rigid fertilizer briquette having a shape and mechanical strength which adapt it to be hammered into the ground without significant shattering.

8. A method for making a fertilizer briquette adapted to be hammered while unsupported into the ground without substantial shattering thereof which comprises:
preparing a homogeneous mixture of non-fibrous particles comprising pulverulent, granular NPK fertilizer source materials and an uncured thermosetting urea-formaldehyde resinous binder by mulling together said source materials and said binder until the said source materials are coated with the binder;
charging the resulting mixture into the mold cavity of a briquetter; then compacting said mixture into a briquette having a shape which adapts it to be hammered into the ground and a green strength which permits it to be handled without substantial crumbling, said green briquette having a blunt end;
curing the resinous binder into a substantially water insoluble thermoset resin to form a rigid fertilizer briquette having a shape t mechanical strength and impact resistance which adapts it to be hammered while unsupported into the ground without significant shattering; and dipping the blunt end in a solution of a resin to form a cap thereon.

9. A method for making a fertilizer spike-shaped briquette, said method comprising:
mixing a granular NPK source material with an uncured thermosetting resinous binder to form a mixture;
compressing said mixture at a pressure capable of forming without the need for additional heat a solid green spike having a sufficient strength to be ejected from the die and maintain its shape; and then allowing the binder in the spike to completely cure so as to form a hard rigid spike drivable into the ground by a hammer without significant shattering.

10. The method of Claim 9 wherein the binder is allowed to cure at room temperature.

11. The method of Claim 9 wherein the binder is allowed to cure at atmospheric conditions.

12. The method of Claim 9 wherein the binder is allowed to cure at an elevated temperature.

13. The method of Claim 9 wherein the proportion of the binder in said mixture is from about 5 to 15 weight percent and the proportion of moisture is less than 5 weight percent.

14. The method of Claim 9 wherein the binder is urea-formaldehyde.

15. The method of Claim 9 wherein a relatively small quantity of said binder is used in the mixture.

16. The method of Claim 14 wherein the proportion of the binder in said mixture is from about 7 to 10 weight percent.

17. The method of Claim 14 wherein the binder has a urea-formaldehyde ratio ranging from about 1.00 over 1.38 to about 1.00 over 1.80.

18. The method of Claim 14 wherein the mixture includes less than 5 weight percent of moisture.

19. The method of Claim 14 wherein the mixture includes from about 2 to about 5 weight percent moisture.

20. The method of Claim 14 or 17 further comprising the step of heating said mixture to about 180°F.

21. A method for making a fertilizer spike-shaped briquette, said method comprising:
mixing a granular NPK source material with uncured urea-formaldehyde resinous binder to form a mixture;

subjecting said mixture to compression by a briquetter at a pressure capable of forming, without the need for additional heat, a solid green spike having a sufficient strength to be ejected from the briquetting die and maintain its shape; then, allowing the binder in the spike to completely cure so as to form a hard rigid spike drivable into the ground by a hammer without significant shattering.