FIELD: agricultural chemistry.
SUBSTANCE: invention relates to a method for coating urea-containing granules with biodegradable polymers, to a set of installations, and to the use of a set of installations for coating urea-containing granules with biodegradable polymers. The method for coating urea-containing granules with biodegradable polymers includes at least following stages: a) gaseous carbon dioxide (2b) is compressed and condensed, and liquid carbon dioxide is obtained; b) pressure and/or temperature are increased above the critical point of carbon dioxide, and supercritical carbon dioxide (2a) is obtained; c) biodegradable polymer (1b) is dissolved in supercritical carbon dioxide (2a), and polymer-containing solution (3) is obtained, d) polymer-containing solution (3) is mixed with urea-containing granules (4a) by spraying it on them and/or bringing it into contact with them. At the same time, temperature and/or pressure are simultaneously or subsequently decreased below the critical point of carbon dioxide, and urea-containing granules (4b) with coating and gaseous carbon dioxide (2b) are formed. The set of installations for coating urea-containing granules with biodegradable polymers includes at least a urea synthesis installation and installation (26) for application of coating to urea-containing granules. At the same time, installation (26) for application of coating to urea-containing granules includes at least: line (14) for supply of supercritical carbon dioxide (2a) from the urea synthesis installation and line (15) for supply of biodegradable polymer (1b); mixing device (8) for supercritical carbon dioxide (2a) and biodegradable polymer (1b), which is connected to line (14) for supply of supercritical carbon dioxide (2a) and line (15) for supply of biodegradable polymer (1b); device (9) for application of coating, connected to mixing device (8) and line (12) for supply of granules (4a). In this case, device (9) for application of coating has first outlet (10) for gaseous carbon dioxide (2b) and the second outlet for product (4b) with coating.
EFFECT: invention allows for obtaining fertilizer granules with coating, which can be produced without the use of solvents harmful for the environment and/or health.
19 cl, 2 dwg
