Method for obtaining a granulated phosphate fertiliser and phosphate fertiliser obtained

A method for obtaining a granulated phosphate fertiliser which comprises the steps of:

• i) granulating ground phosphate rock in a granulator, the ground phosphate rock having a particle size between 100 and 500 μm and a humidity between 1 and 2%, a natural carbon source in ground state with a particle size between 0.1 and 1 mm and a humidity of 25 to 35%, a metabolic inducer of phosphorus-solubilising microorganisms and water to obtain a granulate;
• ii) drying the granulate obtained in step i) by means of a stream of hot air progressively heated from 50° C. to 290° C., avoiding rapid evaporation of the water, with a granule outlet temperature of 50° C. to obtain a dry granulate;
• iii) cooling the dry granulate by means of a stream of dry air at room temperature in the range of 20° C. to 25° C. to obtain cooled granules;
• iv) sieving the cooled granules for removing non-granulated raw material and deteriorated granules to obtain granules with a particle size having an average diameter between 1.5 mm and 3.5 mm;
• v) drying the granules obtained by step iv) by direct heating at a temperature of 300° C. for reducing humidity of the granulate to a maximum of 2%, with a granule outlet temperature of 40° C. to obtain a granulate;
• vi) cooling the granulate obtained by step v) by means of a stream of dry air at room temperature in the range of 20° C. to 25° C.;
• vii) optionally, adding 105 ucf/g of additional phosphorus-solubilising microorganisms of the genus bacillus or pseudomonas after step i);
• viii) sieving the granulate obtained by step vii) to obtain granules with an average particle size between 2 mm and 4 mm.