| 摘要 |
<p>The parent patent claims a process for purifying solns. contg. alkali carbonates, sulphates, hydroxides or bicarbonates as well as one or more of V, U and Mo, present as alkali salts and mineral and/or organic impurities, by (a) adding lime to the boiling soln. to convert the (bi)carbonates to hydroxides; (b) sepg. and washing the resulting ppte. contg. CaCO3 and a mixt. of other (in)organic calcium salts; (c) concentrating the soln. obtd., together with the wash liquor, by evapn. to obtain a soln. of at least 50% alkali hydroxide concn. and to ppte. alkali sulphates; and (d) sepg. the ppte. to obtain an alkali hydroxide-rich liquor. In the present invention, the alkali sulphate ppte. is dissolved in an aq. medium, the soln. is treated with barium aluminate and then CO2, the ppte. obtd. is sepd. from the resulting carbonate soln. which is recycled, and the ppte. is heat treated to regenerate barium aluminate for recycling. The process is used for purifying solns., which have been used for leaching U or V minerals, after sepn. of the metal values, to regenerate the alkali (bi)carbonate leaching soln. The alkali sulphate by-product of the parent patent process is treated, without causing environmental pollution, to give additional carbonate soln. for recycling, SO2 which can be recovered, and CO2.</p> |
