Highly conc. aq. magnesium chloride soln. prodn. - from soln. also contg. potassium and sodium chloride and magnesium sulphate by multistage process

摘要

In the multistage prodn. of highly conc. aq. MgCl2 soln. (I) with low KCl, NaCl and MgSO4 contents from solns. (II) contg. NaCl, KCl, MgCl2 and MgSO4, a mixt. (III) of NaCl and carnallite (IV) is crystallised from conc. MgCl2 soln. (III) is recycled and mixed with (II). The (IV) decomposes and the resultant soln. contg. solid NaCl and KCl is mixed with pt. of (I) and cooled, so that more KCl and NaCl crystallises. The mixed soln. is filtered and conc. by evapn. and the solids formed are filtered off. The filtrate is cooled, so that NaCl and (IV) crystallise, and the salt mixt. is filtered off and recycled. The cooled filtrate is discharged as (I). (I) is used in the prodn. of Mg and MgO. The process is simple, avoids the addn. of foreign chemicals, ensures easy sepn. of the solid salts from the mother liquors and is very economical.