Use of supercritical CO2 as solvent for organic polymers in a method for coating urea-containing granules

A process for coating urea-containing granules with organic polymers, the process comprising:

• compressing and condensing gaseous carbon dioxide to obtain liquid carbon dioxide, wherein the compressing of the gaseous carbon dioxide occurs in a first step in a low-pressure compression step and in a second step in a high-pressure compression step, wherein the low-pressure includes from 5 bar to 10 bar and the high-pressure includes from 20 bar to 35 bar;
• increasing at least one of pressure or temperature above a critical point of carbon dioxide to obtain supercritical carbon dioxide;
• dissolving an organic polymer in the supercritical carbon dioxide to obtain a polymer-containing solution;
• and
• mixing the polymer-containing solution by at least one of spraying the polymer-containing solution onto or bringing the polymer-containing solution into contact with urea-containing granules, in which
• a simultaneous or subsequent lowering of temperature and/or pressure below the critical point of carbon dioxide occurs, and
• coated urea-containing granules and gaseous carbon dioxide are obtained.