BEHAVIOR OF NI(II) IN THE H2O-NH3-SO2-MNO2 SYSTEM

Nickel losses have been observed from leach liquors obtained during ex traction of metal values from ocean nodules using ammonium sulphite. S tudies have been carried out to establish the reasons for such losses. Behaviour of Ni(II) in the following systems was studied: (a) NH3(NH4 )(2)SO3- (b) NH3-partially oxidised (NH4)(2)SO3 using oxygen-H2O, and (c) NH3-partially oxidised (NH4)(2)SO3 using MnO3-H2O. Nickel added du ring or after reduction of MnO2 in NH3-(NH4)(2)SO3 solution resulted i n its precipitation as a crystalline compound. The XRD pattern showed discrete peaks but did not correspond to any compound cited in ASTM. D etailed work of DT-TGA and chemical analysis supported the formation o f Ni0.75Mn0.25(NH3)(4)S2O6 . 2 H2O in nodule leach liquor.