Patent ID: 9487452
Filing Date: 2016-11-08
CPC Classification: C05B,C05C,C05G,C07C

Claim Text:
1. A method of producing passivated particles comprising urea, or urea-based compounds, for fertilizer blends, said method comprising: treating urea containing particles with 0.1 to 2.0 weight % of a mineral acid that reacts with urea, so as to create an acidified particle surface and form a grasping layer made of a double salt of urea; and thereafter adding an excess, 2 to 6 weight %, based on the weight of the urea-containing particles, of a solid base in powder form to the particles so as to coat the acidified particle surface and obtain a layer comprising 1) said grasping layer, 2) metal salts formed from reacting said mineral acid with said solid base in powder form, and 3) unreacted base.