METHOD OF GRANULATION OF NITROGEN FERTILIZERS AND DEVICE FOR REALIZATION OF THIS METHOD Russian patent published in 2004 - IPC

FIELD: production of mineral fertilizers, granulated nitrogen fertilizers in particular, such as ammonium nitrate; chemical and other industries.

SUBSTANCE: proposed method includes increasing sizes of fine granules to required level by repeated spraying the melt of nitrogen fertilizers on surfaces of granules of seeding material-tailings at temperature below crystallization temperature by 20-25 C of 96-98% of melt which is returned for repeated granulation and classification. Circulating flow of fine granules is in free fall in form of vertical screen at thickness no less than 50 mcm. Product thus formed is repeatedly directed to vertical screen for repeated spraying till required sizes of granules have been obtained; then, fraction is removed from circulating loop by means of string-type limiting sieve. Device proposed for realization of this method is made in form of multi-section apparatus; its lower section is provided with twin circulating proportioner at adjustable speed of revolutions and auger for unloading large lumps, vertical shaft, vertical transportation air duct which widens upward, settling chamber with pipe unions connected to shaft and to air duct, string-type limiting sieve, scraper chain conveyer for cleaning strings and swivel drum with flexible belt cloth wound on it. Mounted on either side of vertical shaft collectors for delivery of melt which are provided with injectors mounted at angle of 45 deg. relative to level. Sieve is mounted in inclined position below inlet of settling chamber. Chain conveyer is also inclined and is located under sieve. Length of flexible belt cloth is sufficient for complete overlapping of product passage zone; one end is secured on drum and second end is held in position parallel relative to sieve by means of two ropes provided with weights thrown through blocks on the outside of settling chamber and enclosed in protective casings. Belt cloth is located under sieve for removal of fine and commercial fractions through pipe union. Located inside connecting pipe union of settling chamber is flexible rubber apron secured on upper transversal rod and thrown through similar rod which is shifted relative to axis of pipe union.

EFFECT: possibility of obtaining homogeneous fraction; increased yield; reduced power requirements; enhanced operational reliability.

5 cl, 3 dwg