METHOD OF PREPARING GRANULATED AMMONIUM NITRATE-SULPHATE FERTILISER Russian patent published in 2010 - IPC C05C1/00 

FIELD: chemistry.

SUBSTANCE: method of preparing ammonium nitrate-sulphate fertiliser from thin pulp of ammonium nitrate-sulphate involves preparation of a thin pulp of ammonium nitrate-sulphate with crystallisation centres of a double salt which has two ammonium nitrate molecules and one ammonium sulphate molecule by continuously feeding molten ammonium nitrate treated with ammonia and a first portion of ammonia sulphate by feeding jet steam at temperature 60-120°C; molar ratio ammonium nitrate: ammonium sulphate ranges from 1.8 to 2.2:1. The obtained pulp which contains 6-15 wt % water is mixed with a second portion of crystalline ammonium sulphate and the returned recycled product and granulated at temperature of the moist granulate of 65 - 110°C with molar ratio ammonium nitrate: ammonium sulphate less than 2. The obtained moist granulate is dried with hot air at temperature of the granulate of 50 - 125°C. During simultaneous constant reduction of water content, residual amount of free ammonium nitrate completely reacts to form dry granulate, from which, through sieving, a fraction ammonium nitrate-sulphate fertiliser containing 22-29 wt % nitrogen and 5-15 wt % sulphur in form of sulphate is obtained, as well as fractions with size smaller and larger than the required size, which are combined after grinding the fraction with size greater than the required size, and returned as a recycling product after grinding.

EFFECT: method enables obtaining fertiliser with balanced content of nutrients with high strength of granules.

14 cl, 4 ex