Source of phosphate for agriculture and the food industry

A phosphate salt in solid form of formula Mn(HPO4)y.zH2O in which M is Na, K, NH4, n=2, and y=1;

• or M is Ca, n=1, y=1;
• or M is Al or Fe, n=2, y=3;
• and in which z is 0, 1 or 2;
• said phosphate salt has a phosphate content expressed as a P205 content of between 30 and 50% by weight of the phosphate salt, wherein the cadmium content in said phosphate salt is less than 0.40 ppm.

A method for the preparation of the phosphate salt according to claim 1, the method comprising the following steps:

• a) a phosphate source digestion using a first aqueous solution of hydrochloric acid, with formation of an attack liquor consisting of an aqueous phase comprising phosphate ions and chloride ions in solution, and a first insoluble solid phase containing impurities,
• b) a first separation between the aqueous phase comprising phosphate and chloride ions in solution and the first insoluble solid phase containing impurities,
• c) a neutralisation of said aqueous phase comprising phosphate ions and chloride ions in solution at a pH sufficient to form an aqueous medium comprising chloride ions and to precipitate the phosphate ions in the form of said phosphate salt,
• d) a second separation between said aqueous medium comprising chloride ions and said phosphate salt,
• wherein steps a) and b) are performed at a temperature between 50° C. and 70° C. for a duration less than two hours and in that said first aqueous solution of hydrochloric acid has an HCl concentration less than or equal to 15% by weight.