Patent ID: 7361323

Claim:
Method of producing phosphoric acid, comprising at least one phosphate ore attack with a first aqueous solution of hydrochloric acid having an HCl concentration of no more than 10% by weight, with the formation of an attack liquor, said attack comprising a dissolving of the phosphate of the ore in said first aqueous solution of hydrochloric acid with a yield of attack greater than 80% by weight, expressed as P 2 O 5 , the obtained attack liquor containing this dissolved phosphate in the form of phosphate ions, a first separation, in the attack liquor, between an insoluble solid phase containing impurities and a separated aqueous phase comprising in solution said phosphate ions, chloride ions and calcium ions, a neutralisation of the said aqueous phase separated from the attack liquor by the addition of a calcium compound in order to form with the said phosphate ions a calcium phosphate insoluble in water, which precipitates, a second separation, in the said neutralised aqueous phase, between an aqueous phase comprising in solution calcium ions and chloride ions and a precipitated solid phase based on the said calcium phosphate insoluble in water, and a solubilisation of at least part of the said precipitated solid phase separated, in a second aqueous solution of hydrochloric acid having a HCl concentration greater than that of said first aqueous solution of hydrochloric acid, with the formation of an aqueous solution containing phosphate ions, chloride ions and calcium ions, an extraction of said aqueous solution containing phosphate ions, chloride ions and calcium ions by an organic extraction agent, in order to form an aqueous extraction phase comprising chlorine ions and calcium ions and an organic extraction phase containing phosphoric acid; and a re-extraction of the organic extraction phase by an aqueous re-extraction agent, in order to isolate an aqueous re-extraction phase containing phosphate ions.