| 摘要 |
<p>1,268,124. Purifying phosphoric acids or phosphates. KNAPSACK A.G. 21 Nov., 1969 [30 Nov., 1968], No. 57147/69. Heading C1A. Manganese is removed from phosphoric acids or acid alkali metal phosphate solutions, containing between 100 and 1000 p.p.m. by wt. manganese, based on P 2 O 5 , by establishing in the solution a concentration of magnesium, calcium or iron (II) cations of more than 2000 p.p.m. by wt., based on P 2 O 5 , neutralizing the acid solution with an alkali metal base, so as to establish an alkali metal oxide to P 2 O 5 molar ratio of more than 1À9, and filtering off the resulting precipitate to leave an alkali metal phosphate solution. The cations may be added in the form of MgSO 4 , CaCl 2 or FeSO 4 . Trivalent iron cations present in the solution may be reduced to the bivalent cation, by, for instance, hydrogen sulphide, or compounds yielding hydrogen sulphide such as sodium or barium sulphide.</p> |
