Alkali metal sulphate prodn - by reacting magnesium sulphate soln with solid alkali chloride in presence of ammonia and ammonium

摘要

Conc. or satd. MgSO4 soln is mixed with a recycled soln contg. ammonia and ammonium salts so that Mg(OH)2 having good filtering properties is precipitated and separated. A part of the remaining soln is recycled whilst the remainder is treated with a solid alkali chloride (pref. NaCl or KCl) and NH3 is introduced whereby alkali sulphate crystallises out and is separated. A part of the remaining soln is recycled to the Mg(OH)2-precipitation stage; whilst ammonia is recovered from the other part and returned to the NH3-saturation stage. High alkali sulphate yields are obtd.