Patent ID: 9464009
Filing Date: 2016-10-11
CPC Classification: B01D,C01C,C05C,C07C

Claim Text:
1. A method for preparing a urea/ammonium sulfate (UAS) fertilizer from urea dust and ammonia in a gas stream which comprises contacting said gas stream with an aqueous sulphuric acid solution, thus forming an acid solution of ammonium sulphate and urea; followed by adding ammonia to the acid solution, thus forming a neutralized solution of urea and ammonium sulphate (AS) in water, followed by concentrating said neutralized solution to a melt comprising less than 5 wt % of water, and mixing the melt with an additional amount of ammonium sulphate, followed by transforming said melt into solid particles comprising urea and ammonium sulphate as a UAS fertilizer, wherein said gas stream is an exhaust waste gas from a urea plant, a urea-granulation tower, a urea-prilling tower or chemical fertilizer plant, and which exhaust waste gas stream is the sole source of the urea in the UAS fertilizer.