Patent ID: 11970427
Assignee: NORTH UNIVERSITY OF CHINA
Field: Basic materials chemistry (Chemistry)
Classification: CPC C | IPC C

Claim 4:
5. A method of preparing the microelement amino acid chelate-UF slow-release fertilizer of claim 1 by reactive extrusion, comprising:
(S1) feeding formaldehyde and urea to a reactor to form a first reaction system; and adjusting a pH of the first reaction system followed by a reaction to obtain a hydroxymethylurea solution;
(S2) dissolving an amino acid in the hydroxymethylurea solution followed by addition of a microelement-containing compound to form a second reaction system; and adjusting a pH of the second reaction system;
(S3) sealing a die opening between a reaction unit and an extrusion unit of a reaction-extrusion integrated machinery; and feeding the second reaction system into a reaction extruder of the reaction unit of the reaction-extrusion integrated machinery;
(S4) turning on a screw of the reaction extruder to allow the second reaction system to undergo a reaction at a first preset temperature and a first preset rotation speed, and simultaneously starting a vacuumization-devolatilization device of the reaction extruder to remove water, so as to obtain a third reaction system;
(S5) opening the die opening between the reaction unit and the extrusion unit; turning on a twin-screw extruder of the extrusion unit; conveying, by the screw of the reaction extruder, the third reaction system to the twin-screw extruder; and extruding, by the twin-screw extruder, the third reaction system at a second preset temperature and a second preset rotation speed to obtain a strip-shaped extrudate; and
(S6) drying the strip-shaped extrudate followed by granulation to obtain the microelement amino acid chelate-UF slow-release fertilizer in a form of a cylindrical granule.