FERTILIZER PRODUCTION PROCESS Russian patent published in 2000 - IPC

FIELD: organic fertilizer production. SUBSTANCE: invention relates to oligo-methylene-urea product suitable as fertilizer. Methylol-urea composition is prepared by adding minimal amounts of urea and aqueous solution of formaldehyde at total urea-to- formaldehyde molar ratio from 1:1 to 2:1 into the first reactor maintaining residence time at least 0.5 hr and temperature within a range of 40 to 95 C and pH from 6.5 to 11. Resulting composition is transferred into the second reactor wherein temperature and pH are maintained, respectively, from 5 to 35 C and from 1.8 to 3.5 to form primary oligo- methylene-urea suspension. Secondary oligo-methylene-urea suspension is prepared by transferring either methylol-urea composition or primary oligo-methylene-urea suspension into the third reactor operated at temperature from 5 to 35 C and pH from 1.8 to 3.5. Primary or secondary oligo-methylene-urea suspension is further filtered to give oligo- methylene-urea precipitate and filtrate. The latter is returned into the second or third reactor and the former is neutralized and dried. Nitrogen level in the thus obtained product is 39-40%. EFFECT: minimized volumes of liquids involved in process and improved capability of product to be filtered off. 18 cl, 1 dwg, 8 ex