Process for producing granulated potassium sulphate and potassium magnesium sulphates, and the granulates obtained thereby

A process for preparing a potassium granulate which is free from additives and has a particle size distribution of between 2 and 5 mm, said granulate selected from the group consisting of granulated potassium sulphate and potassium magnesium sulphate, said process comprising the following steps:

• (a) grinding a salt selected from the group consisting of potassium sulphate and potassium magnesium sulphate to obtain a ground product having the following average particle size distribution:
• less than about 150 mesh, about 8%;
• 150 to about 200 mesh, about 12%;
• 200 to about 270 mesh, about 15%;
• 270 to about 400 mesh, about 15%;
• and greater than 400 mesh, about 50%;
• (b) mixing the ground product of step (a) with a corresponding unground salt selected from the group consisting of potassium sulphate and potassium magnesium sulphate until a predetermined particle size distribution is obtained for the mixture;
• (c) treating the mixture of step (b) with a hot, saturated solution of a corresponding salt selected from the group consisting of potassium sulphate and potassium magnesium sulphate until a wet paste is obtained;
• (d) granulating said paste to obtain a granulate having the following average particle size distribution:
• less than about 35 mesh, about 1.16%;
• 35 to about 48 mesh, about 0.16%;
• 48 to about 100 mesh, about 9.50%;
• 100 to about 150 mesh, about 18%;
• 150 to about 200 mesh, about 19.17%;
• 200 to about 270 mesh, about 14.67%;
• 270 to about 400 mesh, about 12.34%;
• and greater than 400 mesh, about 25%;
• and
• (e) drying the granulate thus obtained.