| 摘要 |
PCT No. PCT/FR90/00507 Sec. 371 Date Jan. 6, 1992 Sec. 102(e) Date Jan. 6, 1992 PCT Filed Jul. 4, 1990 PCT Pub. No. WO91/00244 PCT Pub. Date Jan. 10, 1991.Process for treating phosphoric acid for removing heavy metal cations, in particular cadmium, and sludges contained in the acid, characterized in that concentrated phosphoric acid having a low solids content is used and in that the calcium sulfate supersaturation of the phosphoric acid is controlled to form a compound of the formula I: (SO4)1-x(PO4)x(H)yCa1-67 M; where x is between 0.5*10-2 and 1*10-1; y is between 0 and x+(delta); (delta) indicates the chemical substitution of calcium by other metal cations; and M represents one or more metal cations contained in the initial phosphoric acid, whose total charge is approximately equal to 2(delta)+x-y. The following "Brief Description of Drawings" has been inserted between lines 19 and 20 on page 4 of the specification to comply with 37 CRF 1.74 and MPEP 608.01(f). The sole FIGURE of the Drawings is a flow diagram illustrating one embodiment of the process according to the present invention. |
