Method for making formulated nitrogenous and complex fertilizer in highly homogenized spherical granule form starting from urea-formaldehyde liquid resins and the fertilizer made thereby
OwnerGiancarlo Costa, Giuseppe Rizziinventors
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Abstract
The present invention relates to a method for making formulated nitrogenous and complex fertilizers, in granule form, suitable for slowly releasing nitrogen, comprising the steps of preparing an aqueous urea/formaldehyde dispersion with a molar ratio from 0.8:1 to 2:1, adding an aqueous catalyzer solution in a weight ratio from 0.1 to 4%, controlling the pH of the aqueous dispersion to hold it within a range from 4.0 to 7.0, and supplying the aqueous dispersion to a recirculating granulating device, as a growth seed.
Claims11
A method for making a nitrogenous and complex fertilizer, for slowly releasing nitrogen in granule form, said method comprising the steps of preparing an aqueous urea-formaldehyde resin dispersion or mixture, wherein said resin dispersion is prepared by a reaction and a heating and cooling system, at atmospheric pressure and room temperature, formaldehyde, urea and water, with a formaldehyde/urea first ratio from substantially 0.8:1 to 2:1, thereby providing said aqueous dispersion, heating and reacting said aqueous dispersion to a temperature from substantially 80° C. to 110° C., controlling the pH from 4 to 7, monitoring at even time periods a viscosity of said dispersion and further adding to said aqueous dispersion a reaction stopping agent to achieve, upon stopping said reaction, a substantially pH neutrality condition, supplying the mixture in a liquid form to a storing tank, conveying said mixture from said storing tank to a drying and granulating device for simultaneously reactively drying and granulating said mixture to provide a solid support and spraying on said solid support said mixture to provide urea/formaldehyde substantially perfectly spherical homogenous fertilizer granules having a density in a range from 0.5 to 1 g/cm3, preferably from 0.8 to 0.9 g/cm3, a total nitrogen contents from 36 to 42%, preferably from 38 to 40% by weight, an ureic nitrogen contents less than 5% by weight, a nitric nitrogen content less than 10% by weight, preferably from 2 to 5% by weight, an ammoniacal nitrogen contents less than 15% by weight, preferably from 3 to 8% by weight, and a diameter from 0.5 to 5 mm.
Dependencies are inferred from the claim text.