Patent ID: 7824634

Claim:
A method for etching phosphate ore, consisting of the sequential steps of: (a) a digestion, in one step and in co-current, of phosphate ore having a P 2 O 5 content of more than 20% by weight and an aqueous solution of hydrochloric acid having an HCI concentration of less than 10% by weight, which results in formation of an etching liquor consisting of an aqueous phase, in which calcium phosphate is in solution, and an insoluble solid phase which contains impurities, (b) a preliminary neutralization of the etching liquor containing calcium phosphate in solution to a first pH which is between about 0.8 and 4.0, with precipitation of impurities, (c) a first separation between the insoluble solid phase and the aqueous phase of the neutralized etching liquor, during which an isolation of the precipitated impurities takes place, (d) a subsequent neutralization of the separated aqueous phase resulting from the first separation to a second pH which is greater than said first pH, with precipitation of calcium monohydrogen phosphate, and (e) a second separation in this subsequently neutralized aqueous phase between an aqueous solution of calcium chloride and the precipitated DCP.