Behavior of Crystallization Stripping of Ag Carbonate and Ag-Ni Composite Carbonate and Their Physicochemical Properties

摘要

The behavior of the crystallization stripping of Ag carbonate and Ag-Ni composite carbonate was investigated using Versatic Acid 10 as an extractant and pressurized carbon dioxide as a crystallizing agent. The physicochemical properties such as crystal structure, thermal decomposition and distribution of Ag and Ni were also investigated on the obtained crystallized products.The possibility of crystallization stripping of Ag and Ni from the organic phase has been confirmed by calculating the aqueous pH equilibrated with pressured carbon dioxide. The reaction of crystallization stripping of Ag and Ni depends on an extractant concentration, a pressure of carbon dioxide and a metal concentration in an organic phase. The obtained crystallized product of Ag is confirmed to be Ag_2CO_3 crystal, which is characterized by the needle like crystal or polyhedron crystal. Heating of the crystallized product of Ag in air and hydrogen causes a thermal decomposition to metal Ag powder When the crystallization stripping is carried out from the organic phase containing Ag and Ni, the simultaneous crystallization takes place to form the composite carbonate of Ag and Ni. The composite carbonate consists of mixture of Ag_2CO_3 and NiCO_3 centre dot 2Ni(OH)_2 centre dot 4H_2O.