Process for concentrating a phosphoric acid solution

Abstract

The present invention relates to a process for concentrating an aqueous phosphoric acid solution comprising at least the following steps (Step 1) providing at least one aqueous phosphoric acid [hereinafter, acid (P1)], wherein said acid (P1) has a phosphorus content from 10.0 wt.% to 35.0 wt.%, expressed as P2O5, relative to the total weight of the acid (P1); and a Minor Element Ratio (MER) equal to or more than 0.080 and a solid content in an amount of YP1 wt.%, which is ranging from 1.00 wt.% to 7.00 wt.%, relative to the total weight of the acid (P1); (Step 2) providing at least one aqueous phosphoric acid [hereinafter, acid (P2)] having, relative to the total weight of the acid (P2), a phosphorus content equal to or more than 50.0 wt.%, expressed as P2O5,and a solid content in an amount of YA wt.%, which is ranging from 0.00 wt.% to 5.8 wt.%,; (Step 3) forming at least one aqueous phosphoric acid mixture [hereinafter, mixture (A)] by mixing the acid (P1) and the acid (P2), wherein said mixture (A) has, relative to the total weight of the mixture (A), a phosphorus content equal to or more than 20.0 wt.%, expressed as P2O5; a solid content of YA wt.%, which is ranging from 0.50 wt.% to 7.00 wt.%; (Step 4) mixture (A) is submitted to a separation process, wherein at least part of the solid content of the mixture (A) is separated from the mixture (A), thereby forming an aqueous phosphoric acid [hereinafter, acid (P3)] which has a solid content of YP3 wt.%, which is lower than YA wt.% but equal to or less than 5.00 wt.%, relative to the total weight of the acid (P3); (Step 5) concentrating the acid (P3), thereby producing an aqueous phosphoric acid [hereinafter, acid (P4)] having a phosphorus content equal to or more than 50.0 wt.%, expressed as P2O5, relative to the total weight of the acid (P4); (Step 6) adding at least part of the acid (P4) obtained in step 5 to step 2 so as to contribute to providing the acid (P2) in step 2.

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