Method for etching phosphate ores
AssigneeEcophos S.A.
InventorMohamed Takhim
Life of this patent
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Abstract
A method for etching phosphate ores includes a single-pass digesting of ores which P205 content is greater than 20% in weight by a hydrochloric aqueous acid solution having an HCI concentration less than 10% by weight with an etching solution formation and the separation of the insoluble solid phase and the aqueous phase of the etching solution. Preneutralization of the etching solution is accomplished by a neutralizing agent prior to the separation in such a way that the etching solution pH which is less than pH to which an important part of phosphate ions in solution precipitates in the form of calcium monohydrogen phosphate (DCP) is adjusted and in subsequently neutralizing the separated aqueous phase in such a way that a pure DCP is precipitated.
Claims13
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 P2O5 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.
Dependencies are inferred from the claim text.