Preparing fertilizer containing urea and ammonium sulfate, with the latter produced by reacting ammonia in urea-containing solution with sulfuric acid

摘要

Preparation of fertilizer that contains ammonium sulfate and urea. Preparation of fertilizer that contains ammonium sulfate and urea comprises: (1) reacting, at 80-150 deg C and 1-4 bar, a solution containing (wt.%) urea (1-80), optionally also ammonium sulfate at 0-40 wt.%, to give a weight ratio ammonium sulfate:urea of 5-65:95-35; (2) a melt suspension is formed, with a water content of 5-15 wt.%, and is optionally concentrated to 0.1-0.3 wt.% water and converted to prills or granulate; (3) the vapor/gas mixture formed in step (1), containing steam, ammonia, carbon dioxide and optionally residues of ammonium sulfate and urea, is then passed to an absorber with recycle liquid and sulfuric acid (and optionally water) added so that ammonia reacts to form ammonium sulfate. The ammonium sulfate concentration in the recycle liquid is controlled at 30-40 wt.% and this liquid is returned to step (1).