A method for the preparation of alkali metal sulfate by reaction of mgso deep 4 - solution with a solid alkali metal chloride into nh deep 4 - salt - while avoiding the solution containing precipitation of mg (oh) deeply 2 in the warm mixed solution

摘要

Aq. MgSO4 soln. practically satd. at 50-70 degrees C. is mixed with a recycled soln. of ammonium salts and NH3, the concn. of ammonium salts being 300 G./l. (pref. 300-400 g./l. so that pptn. of Mg(OH)2 does not occur, solid alkali chloride is stirred into the warm (50-80 degrees C.) soln. in an amt. approx. stoichiometrically equiv. to the amt. of MgSO4, the mixture is cooled to 50 degrees C. (pref. 20-40 degrees C.) while passing NH3 into it until it is satd. with NH3; Mg(OH)2-contaminated alkali sulphate which crystallises out is sepd. off and subjected to any desired further processing, part of the resulting mother liquor is recycled into the mixed soln., and NH3 is recovered from the remainder or the mother liquor by conventional procedures to give a practically NH3-free residual soln. which is removed from the system.