Patent ID: 6048378
Filing Date: 2000-04-11
Classification: C05C,C05G,C08G

Abstract:
A method of preparing controlled release nitrogen particulate fertilizers containing between about 5 and 40 percent nitrogen which exhibit single growing season nitrogen availabilities to plants of about 80 percent or more, comprising:(a) comingling and coreacting aqueous formaldehyde, urea, and ammonia in mol ratios of between 1 to 1.65 to 0.03 and 1 to 1.85 to 0.30, while maintaining temperature between 85 and 95.degree. C., pressure between 40 and 1000 mm Hg, pH between 8 and 9, for a period of time between 15 and 45 minutes until the formaldehyde is completely reacted with the urea and ammonia to form a liquid condensate solution, containing less than 0.1 percent ammonia nitrogen and less than 5 percent urea nitrogen;(b) admixing the liquid condensate solution with sufficient acid dehydrating catalyst to reduce pH to between 3 and 4 in a period of time amounting to between 10 and 60 seconds, and then maintaining a dehydrating reaction temperature of between 110 and 130.degree. C. for a period of time amounting to between 1 and 10 minutes, until more than 70 percent of the nitrogen is converted to controlled release nitrogen condensates and sufficient water has been evaporated to produce particulate solids; and,(c) neutralizing the particulate solid condensates to a pH between 6 and 7 to stop the dehydrating condensation reaction before more than 20 percent of the controlled release nitrogen form polymeric condensates which are hot water insoluble and unavailable to plants in a single growing season.