| 摘要 |
<p>The parent patent describes a process for purifying solns. contg alkali metal (bi)carbonate, sulphate and/or hydroxide as well as one or more of vanadium, uranium and molybdenum in the form of the alkali metal salt(s). The process comprises (i) treating the soln. at its b.pt. or above with 0.1-20 times the stoichiometric amt. of lime required to convert the (bi)carbonate content into alkali metal hydroxide (ignoring the amt. of lime required to ppte. insol. calcium cpds. of V,U and MO); (ii) sepg. the alkali metal hydroxide-enriched liquor from the ppte cotg. mainly calcium carbonate and a mixt. of other (in)organic calcium salts, and washing the ppte; (iii) concentrating the combined liquor and wash liquor by evapn. to an alkali metal hydroxide content of at least 50% to form a second ppte; and (iv) sepg. the ppte. to recover the alkali metal hydroxide-rich liquor. In the present invention, the sepd. second ppte, comprising a mixt. of alkali metal molybdate and sulphate, is dispersed in an aq. acid liquor (pref. a sulphuric acid-contg. liquor), which is heated under pressure, to ppte. anhydrous MO3 and the ppte. is sepd. to leave a liquor contg. mainly alkali metal sulphate. Process is used to purify leach solns. for recycling, in the leaching of uranium or vanadium minerals which also contain molybdenum, after sepn. of the metal values. The molybdenum, is recovered directly in the oxide form and the problems of the previous sulphide ppte. method are avoided (e.g. elimination of pollution by hydrogen sulphide, risk of formation of the blue oxide and the requirement for calcining the prod.).</p> |
