Decomposition of ammonium sulphate from demanganised leach solution of manganese nodules by lime treatment

Abstract

Results of decomposition of ammonium sulphate by lime from ammoniacal leach solution are presented. The effect of temperature (50-95 degrees C), ammonia concentration (40-80 g/L), ammonium sulphate concentration (80-120 g/L), amount of CaO [1-7.5 % (wt/vol)] on decomposition of ammonium sulphate was determined. The results indicated that decomposition of ammonium sulphate in leach liquor was largely determined by the amount of CaO used. Under standard experimental conditions of 80 degrees C, 60 g/L NH(3) and 120 g/L (NH(4))(2)SO(4) in 1 h 72 to 87% decomposition was achieved when 1 to 1.5 times stoichiometric CaO was used. The metal ions were found to be stable under various experimental conditions. Initial ammonia concentration did not affect the decomposition of ammonium sulphate.