Chemistry: fertilizers – Processes and products – Organic material-containing
Reexamination Certificate
1998-04-17
2001-09-25
Langel, Wayne (Department: 1754)
Chemistry: fertilizers
Processes and products
Organic material-containing
C071S029000, C071S030000
Reexamination Certificate
active
06293985
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for granulating fertilizer products and more particularly, the present invention relates to a method for impregnating urea into a fertilizer material and granulating a pellet.
BACKGROUND OF THE INVENTION
The augmentation of fertilizer compounds with a treatment of urea, typically by spraying or aerosol has been practiced in the art. The most undesirable aspect of the treatment stems from the fact that urea is water soluble and since it is currently applied topically, much of the compound is simply wasted by washing away from rain, irrigation etc. This is a costly procedure with limited efficacy. A product and procedure whereby the urea may be mixed or crystallized within the fertilizer matrix is required to overcome the wastage problem. The present invention solves this problem.
SUMMARY OF THE INVENTION
One object of one embodiment of the present invention is to provide an improved fertilizer product and method of incorporating urea from a source thereof into the fertilizer.
A further object of one embodiment of the present invention is to provide a method granulating a fertilizer feedstock, comprising the steps of:
providing a compound containing urea;
providing a source of ammonium sulfate in a size distribution of 3 mesh to about 10 mesh;
introducing the urea and the ammonium sulfate into a drum granulator;
maintaining a temperature in the drum granulator sufficient to keep the compound in a liquid state for mixture with the ammonium sulfate; and
cooling the mixture to form urea bearing ammonium sulfate granules.
In order to facilitate easier particle rolling within the drum, the drum may be lined with rubber, Teflon™, neoprene, inter alia.
In view of the fact that the granulated pellets contain a relatively high degree of empty interstitial space by virtue of the crystalline structure, this space provides a particularly useful volume within which to recrystallize urea.
In accordance with a further object of one embodiment of the present invention, there is provided a fertilizer granule, comprising:
a potassium granule containing about 20% empty interstitial volume; and
urea in the volume.
In terms of the type of urea compounds that may be used in the practicing of the present invention, examples include urea formaldehyde, urea-ammonium orthophosphate, urea-ammonium polyphosphate, urea form etc. Other suitable examples which are compatible with the chemistry involved will be appreciated by those skilled in the art.
A still further object of one embodiment of the present invention is to provide a method granulating a fertilizer feedstock, comprising the steps of:
providing a compound containing urea;
providing a source of potassium sulfate in a size distribution of 3 mesh to about 10 mesh;
introducing the urea and the potassium sulfate into a drum granulator;
maintaining a temperature in the drum granulator sufficient to keep the compound in a liquid state for mixture with the potassium sulfate; and
cooling the mixture to form urea bearing potassium sulfate granules.
For enhancing wettability of the feedstock, a surfactant may be added. The surfactant lowers the surface tension of the fertilizer product sufficiently so that the urea can flow into the fertilizer. This is of significant value when the mixture of urea and fertilizer is cooled to above the melting point of the urea since the result is recrystallization of the urea within the matrix of the fertilizer.
A still further object of one embodiment of the present invention is to provide a method granulating a fertilizer feedstock, comprising the steps of:
providing a compound containing urea;
providing a source of potassium chloride in a size distribution of 3 mesh to about 10 mesh;
introducing the urea and the potassium chloride into a drum granulator;
maintaining a temperature in the drum granulator sufficient to keep the compound in a liquid state for mixture with the potassium chloride; and
cooling the mixture to form urea bearing potassium chloride granules.
Intra matrix recrystallization of the urea has been found to substantially increase desirable properties of the so formed granules. Typically, the break strength of the urea bearing pellets or granules exceeds 7 kilograms. This feature is beneficial in that hard particles do not create large quantities of dust; do not break, crumble, etc. during shipping, provide a modified solubility and facilitate a use for urea which would not have been possible based on the current methodology in the art.
Yet another object of the present invention is to provide a method granulating a fertilizer feedstock, comprising the steps of:
providing a compound containing urea;
providing a source of potassium nitrate in a size distribution of 3 mesh to about 10 mesh;
introducing the urea and the potassium nitrate into a drum granulator;
maintaining a temperature in the drum granulator sufficient to keep the compound in a liquid state for mixture with the potassium nitrate; and
cooling the mixture to form urea bearing potassium nitrate granules.
Having thus generally described the invention, reference will now be made to the accompanying drawings illustrating preferred embodiments.
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(Marks & Clerk)
Airborne Industrial Minerals
Langel Wayne
Sharpe Paul S.
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