Chemistry: fertilizers – Processes and products – Organic material-containing
Reexamination Certificate
1999-05-03
2001-04-17
Langel, Wayne (Department: 1754)
Chemistry: fertilizers
Processes and products
Organic material-containing
C071S064120
Reexamination Certificate
active
06217630
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a conditioned fertilizer product, to a method for conditioning fertilizer, and to a method for using conditioned fertilizer product. In particular, the invention relates to the use of a lactic acid derived conditioning agent for conditioning urea containing fertilizer.
BACKGROUND OF THE INVENTION
Granular urea is commonly used as a source of nitrogen in chemical fertilizer. Methods of manufacturing urea fertilizer as well as methods of processing fertilizer into particles via prill and/or granulation techniques are well known. In general, urea is produced commercially by the basic reaction of ammonia with carbon dioxide at elevated temperatures and pressures. Exemplary commercial applications are described in Kirk-Othmer,
Encyclopedia of Chemical Technology,
3rd Ed., Vol. 23 (1983) pgs. 551-562. As described, the reaction products from such commercial processes are normally 70 to 80% aqueous urea solutions which can subsequently be processed to form solid urea particulates, such as granules. See Kirk-Othmer,
Encyclopedia of Chemical Technology,
3rd Ed., Vol. 23 (1983) pgs. 562-572. The resulting urea particles/granules produced therefrom exhibit properties of caking and friability. The caking tendency causes the initially prepared, free-flowing product to change into a dense, solid, essentially singular mass in the storage pile. The friability property refers to the tendency of the urea granules to break easily into smaller particles. As a result, substantial amounts of dust can be generated as a result of handling, transporting, and applying the urea granules to the soil environment. Modern chemical fertilizer application equipment often includes rotating turbine fan type field distribution equipment which can result in breakage of the urea granules. As a result, the smaller particles fall in a shorter trajectory from the fertilizer distributor and form a more narrow and more concentrated swath on the soil surface than originally intended. In addition, the generated dust may cause health problems.
Numerous techniques have been developed for addressing the caking and friability properties of urea. One technique involves the addition of a small amount of formaldehyde as a conditioning agent. In general, formaldehyde is added in a concentration of between about 0.1% to 0.5% by weight and reacts with the urea to form urea-formaldehyde reaction products. While the addition of formaldehyde to urea modifies the caking and friability properties to desirable levels, formaldehyde has been designated as a toxic and/or carcinogenic material by the U.S. Environmental Protection Agency (EPA). This designation may lead to the restriction or total prohibition of the use of formaldehyde in agricultural products, including its use as a conditioning agent in the preparation of urea for fertilizer.
Urea-formaldehyde was developed as an alternative conditioning agent. The following patents discuss the reaction of formaldehyde with urea to form urea-formaldehyde products: U.S. Pat. No. 3,112,343 to Elstrom, et al.; U.S. Pat. No. 4,160,782 to Van Hiatte, et al.; and U.S. Pat. No. 4,204,053 to Allgeuer, et al. Health and safety considerations, however, have limited the use of formaldehyde in fertilizer products. A risk associated with the use urea-formaldehyde conditioning agent is related to storage and handling prior to blending with molten urea due to free formaldehyde in the conditioning agent.
Anti-caking properties have been imparted to fertilizer particles by utilizing clay, talc, and/or surfactants to coat the particles. Additionally, various oils are sprayed on the particles for controlling dust.
Another technique for modifying the caking and friability properties of urea is to treat the urea with lignosulfonates as described in U.S. Pat. No. 4,587,358 to Blouin, and by treating urea with modified lignosulfonate as described by U.S. Pat. No. 5,032,164 to Sanford et al.
Techniques have been developed for using polylactic acid polymers in controlled release applications including agricultural and waste management applications. See U.S. Pat. No. 5,563,238 to Bonsignore et al. and U.S. Pat. No. 5,360,892 to Bonsignore et al. Techniques have been developed for providing granular fertilizer with a decomposable coating. See U.S. Pat. No. 5,176,734 to Fujita et al. which describes using poly-3-hydroxy-3-alkylpropionic acid as a component of a decomposable coating for granular fertilizer.
SUMMARY OF THE INVENTION
A conditioned fertilizer product is provided by the present invention. The conditioned fertilizer product includes urea containing fertilizer and a conditioning amount of lactic acid derived conditioning agent. The lactic acid derived conditioning agent is provided in an amount which is sufficient to reduce the caking and friability properties of the urea containing fertilizer in the absence of the lactic acid derived conditioning agent. In general, the amount of lactic acid derived conditioning agent corresponds to between about 0.1% by wt. and about 5% by wt. The conditioning agent is preferably provided in an amount which is less than 2% by wt. The urea containing fertilizer generally contains at least about 50% by wt. urea. The lactic acid derived conditioning agent is preferably at least one of lactic acid, oligomers of lactic acid, polymers of lactic acid, lactide, oligomers of lactide, polymers of lactide, and mixtures thereof.
The conditioned fertilizer product can be prepared by mixing, at a temperature of between about 135° C. and about 145° C., urea containing fertilizer and between about 0.1% by wt. and about 5% by wt. lactic acid derived conditioning agent. The conditioning agent is preferably provided in a concentration of between about 0.2% by wt. and about 2% by wt., and, more preferably, between about 0.2% by wt. and about 0.4% by wt. The conditioned fertilizer product is preferably provided in the form of granules having an average size of between about 0.7 mm and about 5 mm.
A method for conditioning fertilizer is provided by the present invention. The method includes the steps of mixing urea containing fertilizer and conditioning agent at a temperature of between about 135° C. and about 145° C. to provide a molten mixture of urea containing fertilizer and conditioning agent, and cooling the mixture to provide granules. The conditioning agent is preferably a lactic acid derived conditioning agent. The step of mixing at a temperature of between about 135° C. and about 145° C. is preferably provided for between about 5 seconds and about 120 seconds. The step of cooling preferably includes granulating to provide granules having an average size of between about 0.7 mm and about 5 mm.
A method for using conditioned fertilizer product is provided by the invention. The method includes a step of applying fertilizer granules to soil using motor driven fertilizer spreading equipment. A preferred motor driven fertilizer spreading equipment is a rotating turbine fan field distribution equipment.
REFERENCES:
patent: 3112343 (1963-11-01), Allgeuer et al.
patent: 3195999 (1965-07-01), Chance
patent: 4033938 (1977-07-01), Augurt et al.
patent: 4160782 (1979-07-01), Van Hijfte et al.
patent: 4204053 (1980-05-01), Elstrom et al.
patent: 4214888 (1980-07-01), Young
patent: 4309206 (1982-01-01), Michaud et al.
patent: 4526938 (1985-07-01), Churchill et al.
patent: 4587358 (1986-05-01), Blouin
patent: 4745160 (1988-05-01), Churchill et al.
patent: 4861627 (1989-08-01), Mathiowitz et al.
patent: 5032164 (1991-07-01), Sanford et al.
patent: 5142023 (1992-08-01), Gruber et al.
patent: 5176734 (1993-01-01), Fujita et al.
patent: 5248700 (1993-09-01), Lance
patent: 5338822 (1994-08-01), Gruber et al.
patent: 5360892 (1994-11-01), Bonsignore et al.
patent: 5510526 (1996-04-01), Baniel et al.
patent: 5563238 (1996-10-01), Bonsignore et al.
patent: 5645624 (1997-07-01), Naka et al.
patent: 5700344 (1997-12-01), Edgington et al.
patent: 5714573 (1998-02-01), Randall et al.
patent: 5798435 (1998-08-01), Gruber et al.
patent: 2824112 A1 (1979-12-01)
Chanen Michael J.
Gruber Patrick R.
van Bommel Bernhard George
Cargill Incorporated
Langel Wayne
Merchant & Gould P.C.
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