Abrégé

A method for manufacturing a urea-formaldehyde slow-release nitrogen fertilizer includes steps of: mixing and heating urea and formaldehyde solution with a predetermined molar ratio of urea to formaldehyde; adjusting a PH value of hydroxymethylation reaction of urea and formaldehyde solution to 7.5-10.5; heating the hydroxymethylation reaction of urea and formaldehyde solution to the initial reaction temperature of 50° C.; adding a catalyst to start the hydroxymethylation reaction of urea and formaldehyde solution, and conducting hydroxymethylation reaction intermittently or continuously; heating cold urea-formaldehyde solution using the reaction heat of hydroxymethylation; adjusting the pH value of the methylenation reaction of urea and formaldehyde solution to 3.5-5.0; adding a catalyst; completing the methylenation reaction of urea and formaldehyde solution within 1 to 10 minutes; and performing spraying granulation of slurry after the methylenation reaction of urea and formaldehyde solution in the granulator to obtain a urea-formaldehyde slow-release nitrogen fertilizer.

Classes IPC  ?

• C05C 9/02 - Engrais contenant de l'urée ou ses composés contenant des produits de condensation uréeformaldéhyde
• C05C 9/00 - Engrais contenant de l'urée ou ses composés
• C05G 5/12 - Granulés ou flocons
• C05G 3/90 - Mélanges d'un ou plusieurs engrais avec des additifs n'ayant pas une activité spécifique d'engrais pour influer sur la nitrification des composés d’ammonium ou de l’urée dans le sol
• C05G 1/00 - Mélanges d'engrais faisant partie individuellement de différentes sous-classes de
• C05D 1/02 - Fabrication à partir du chlorure ou du sulfate de potassium ou de sels doubles ou de mélanges de ces sels
• C05B 7/00 - Engrais à base essentielle d'orthophosphates alcalins ou d'ammonium
• C05D 9/02 - Autres engrais inorganiques contenant des éléments à l'état de traces

Abrégé

Disclosed are a multi-coating-structure controlled-release fertilizer and a preparation method therefor, which relate to the field of fertilizers. The multi-coating-structure controlled-release fertilizer comprises fertilizer layers and coating layers which are coated layer by layer, wherein the fertilizer layers and the coating layers are arranged in a spaced manner, at least two fertilizer layers are provided, at least one coating layer is provided, and one of the fertilizer layers is used as a core of the fertilizer; the fertilizer layer contains at least one of a nitrogen fertilizer, a phosphatic fertilizer and a potassic fertilizer, and the coating layer is a polyurea formaldehyde, wherein the polyurea formaldehyde at least contains a polyurea formaldehyde having 2-5 carbon atoms. Elements such as nitrogen, phosphorus, potassium, calcium, magnesium and zinc in the fertilizer can be controlled better to release so as to meet the demands of different crops for different nutrients in different stages of growth. The controlled-release fertilizer is prepared by means of a reaction kettle, a slurry tank, a dusting groove and accessory facilities thereof, and the amount of fertilizer in each layer and the positions at which the fertilizer is coated in whole fertilizer particles can be controlled according to a design program. The whole process can be carried out intermittently, and can also be carried out continuously, and the fertilizer can be produced on a large scale.

Classes IPC  ?

• C05G 3/00 - Mélanges d'un ou plusieurs engrais avec des additifs n'ayant pas une activité spécifique d'engrais
• C05G 3/08 - Mélanges d'un ou plusieurs engrais avec des produits n'ayant pas une activité spécifique d'engrais avec des agents contrôlant dans le sol la nitrification des composés d'ammonium ou de l'urée
• C05G 5/00 - Engrais caractérisés par leur forme

Abrégé

Provided are a sustained-release and controlled-release fertilizer having a core-shell structure and a preparation method therefor, which relate to the field of sustained-release and controlled-release fertilizer production. A sustained-release and controlled-release fertilizer having a core-shell structure comprises a core of fertilizer granules and a polyurea-formaldehyde coating layer coated on the surface of the core of fertilizer granules. The molar ratio of urea to formaldehyde in the raw material of the polyurea-formaldehyde is 1-2.5 : 1, and the polyurea-formaldehyde comprises at least polyurea-formaldehyde having 2 to 5 carbon atoms. The molecular weight of the polyurea-formaldehyde can be varied by adjusting reaction conditions so as to form a membrane structure having different carbon chain lengths. The sustained-release and controlled-release fertilizer having a core-shell structure can not only control the sustained release of a large number of nutrients such as nitrogen, phosphorus and potassium, but also can control the sustained release of trace elements such as calcium, magnesium, iron and zinc, and thus can meet nutrient requirements of different crops.

Classes IPC  ?

• C05G 3/00 - Mélanges d'un ou plusieurs engrais avec des additifs n'ayant pas une activité spécifique d'engrais
• C05G 3/08 - Mélanges d'un ou plusieurs engrais avec des produits n'ayant pas une activité spécifique d'engrais avec des agents contrôlant dans le sol la nitrification des composés d'ammonium ou de l'urée
• C05G 5/00 - Engrais caractérisés par leur forme
• C05C 9/02 - Engrais contenant de l'urée ou ses composés contenant des produits de condensation uréeformaldéhyde

Abrégé

A continuous reactor, comprising a main reaction casing (1) and at least one auxiliary reaction casing (2). A stirring device (14) and a first temperature regulating device are arranged in the main reaction casing (1), and material inlets (3) are provided at the upper end thereof; the auxiliary reaction casing (2) is sleevingly arranged at the outer side of the main reaction casing (1), and a reaction cavity is preserved therebetween; an overflow hole (7) communicating with the reaction cavity is formed on the upper part side wall of the main reaction casing (1); the lower ends of the main reaction casing (1) and the auxiliary reaction casing (2) are provided with pollution discharging openings (11) which are in communication with the outside of the auxiliary reaction casing (2); and the lower end of the auxiliary reaction casing (2) is provided with a discharge opening (12).

Classes IPC  ?

• B01J 19/18 - Réacteurs fixes avec éléments internes mobiles
• B01J 19/00 - Procédés chimiques, physiques ou physico-chimiques en généralAppareils appropriés
• C05C 9/02 - Engrais contenant de l'urée ou ses composés contenant des produits de condensation uréeformaldéhyde