Process for the manufacture of sulphur-containing ammonium phosphate fertilizers

Abstract

The invention relates to a process for the manufacture of sulphur-containing fertilizers comprising the steps of: (a) mixing ammonia, phosphoric acid and water in a reactor unit to obtain an ammonium phosphate mixture; (b) introducing the mixture obtained in step (a) into a granulator unit to obtain granules, wherein a liquid phase comprising elemental sulphur is brought into contact with ammonia, phosphoric acid and water in the reactor unit in step (a) or is introduced in the granulator unit in step (b). The invention further relates to sulphur-containing ammonium phosphate fertilizers, to the use of these sulphur-containing fertilizers to promote the growth of agricultural products and to the agricultural products thus-obtained.

1 . A sulphur-containing fertilizer obtainable by a process comprising the steps of:
 (a) bringing a liquid phase comprising elemental sulphur into contact with ammonia, phosphoric acid and water in a reactor unit to obtain an ammonium phosphate mixture, wherein the elemental sulphur is introduced into the reactor unit substantially at the same time as the other reactants;   (b) introducing the mixture obtained in step (a) into a granulator unit to obtain granules.   
   
   
       2 . A sulphur-containing fertilizer according to  claim 1 , wherein the granules obtained after step (b) are dried in a drying unit. 
   
   
       3 . A sulphur-containing fertilizer according to  claim 2 , wherein the reactor unit in step (a) is a pipe cross reactor unit or a preneutralizer. 
   
   
       4 . A sulphur-containing fertilizer according to  claim 3 , wherein the elemental sulphur is introduced as a slurry of sulphur particles in water. 
   
   
       5 . A sulphur-containing fertilizer according to  claim 4 , wherein the elemental sulphur is introduced as molten sulphur, the temperature of the mixture being kept above 113° C. 
   
   
       6 . A sulphur-containing fertilizer according to  claim 5 , wherein the ammonia is anhydrous gaseous ammonia or a concentrated solution of ammonia in water. 
   
   
       7 . A sulphur-containing fertilizer according to  claim 6 , wherein a potassium salt and/or other plant nutrients has been added to the fines. 
   
   
       8 . A sulphur-containing fertilizer according to  claim 7 , wherein the elemental sulphur is biologically produced elemental sulphur. 
   
   
       9 . A sulphur-containing fertilizer according to  claim 1 , wherein the sulphur-containing fertilizer is a sulphur-containing diammoniumphosphate fertilizer, a sulphur-containing monoammoniumphosphate fertilizer, or a sulphur-containing nitrogen-phosphorous-potassium fertilizer. 
   
   
       10 . A sulphur-containing fertilizer according to  claim 1 , wherein the sulphur content is less than 25% (w/w), based on the final product. 
   
   
       11 . A sulphur-containing fertilizer according to  claim 1 , wherein the sulphur content is between 2% and 18% (w/w), based on the final product. 
   
   
       12 . A sulphur-containing fertilizer according to  claim 1 , wherein the sulphur content is between 5% and 15% (w/w), based on the final product. 
   
   
       13 . A sulphur-containing fertilizer according to  claim 3 , wherein the elemental sulphur is introduced as a slurry of sulphur particles in water, the particle size of the sulphur particles being between 0.5 and 150 microns. 
   
   
       14 . A sulphur-containing fertilizer according to  claim 13 , wherein the elemental sulphur is introduced as molten sulphur, the temperature of the mixture being kept above 113° C. 
   
   
       15 . A sulphur-containing fertilizer according to  claim 14 , wherein the ammonia is anhydrous gaseous ammonia or a concentrated solution of ammonia in water. 
   
   
       16 . A sulphur-containing fertilizer according to  claim 15 , wherein a potassium salt and/or other plant nutrients has been added to the fines. 
   
   
       17 . A sulphur-containing fertilizer according to  claim 16 , wherein the elemental sulphur is biologically produced elemental sulphur. 
   
   
       18 . A sulphur-containing fertilizer according to  claim 3 , wherein the elemental sulphur is introduced as a slurry of sulphur particles in water, the particle size of the sulphur particles being between 1.0 and 100 microns. 
   
   
       19 . A sulphur-containing fertilizer according to  claim 18 , wherein the elemental sulphur is introduced as molten sulphur, the temperature of the mixture being kept above 113° C. 
   
   
       20 . A sulphur-containing fertilizer according to  claim 19 , wherein the ammonia is anhydrous gaseous ammonia or a concentrated solution of ammonia in water. 
   
   
       21 . A sulphur-containing fertilizer according to  claim 20 , wherein a potassium salt and/or other plant nutrients has been added to the fines. 
   
   
       22 . A sulphur-containing fertilizer according to  claim 21 , wherein the elemental sulphur is biologically produced elemental sulphur.