Ammonium nitrate granule and method for the preparation of the same

Abstract

The invention relates to a fertilizer granule containing ammonium nitrate, comprising a core containing ammonium nitrate and a coating layer containing calcium sulphate. The coating layer consists of a mixture containing calcium sulphate and ammonium nitrate. Such a fertilizer granule is preferably produced by contacting the core with an aqueous ammonium nitrate solution and solid calcium sulphate particles, either as a slurry or separately. The production of the fertilizer granulate is safe and easy.

1 . A fertilizer granule containing ammonium nitrate, the fertilizer granule comprising:
 a core containing at least 80% by weight of ammonium nitrate; and   a coating layer comprising a mixture of calcium sulphate and ammonium nitrate covering said core, the coating layer mixture being homogeneous in the radial direction of said granule,   wherein a total nitrogen content of the fertilizer granule is at least 27% by weight.   
     
     
         2 . A fertilizer granule according to  claim 1 , wherein the mixture contains less than 2% by weight of water. 
     
     
         3 . The fertilizer granule according to  claim 2 , wherein the mixture contains less than 1% by weight of water. 
     
     
         4 . A fertilizer granule according to  claim 1 , wherein the ammonium nitrate content of the core is at least 94% by weight. 
     
     
         5 . A fertilizer granule according to  claim 1 , wherein the weight ratio between the core and the coating layer ranges from 40:60 to 80:20. 
     
     
         6 . A fertilizer granule according to  claim 1 , wherein the ratio between the ammonium nitrate and the calcium sulphate of the mixture ranges from 0.1:1 to 1.5:1. 
     
     
         7 . A fertilizer granule according to  claim 1 , wherein the calcium sulphate is calcium sulphate anhydrite, calcium sulphate hemihydrate, or calcium sulphate dihydrate (gypsum), formed in situ. 
     
     
         8 . A fertilizer granule according to  claim 1 , wherein the coating layer is in contact with the core. 
     
     
         9 . A fertilizer granule according to  claim 1 , comprising a second coating layer outside said coating layer. 
     
     
         10 . The fertilizer granule according to  claim 9 , wherein said second coating layer comprises an anti-caking agent. 
     
     
         11 . The fertilizer granule according to  claim 10 , wherein said anti-caking agent is an oil amine. 
     
     
         12 . A fertilizer granule according to  claim 1 , wherein said coating layer comprises from 40 to 60% by weight of ammonium nitrate and from 40 to 60% by weight of calcium sulphate calculated as anhydrite. 
     
     
         13 . A fertilizer granule according to  claim 1 , wherein said coating layer comprises from 8 to 28% by weight of ammonium nitrate and from 72 to 92% by weight of calcium sulphate calculated as anhydrite.