Stripping of silver from Primene JMT loaded with silver thiocyanate complexes

Stripping of silver from Primene JMT loaded with silver thiocyanate complex es was investigated, utilizing hydrolysis, anion exchange and reduction str ipping reactions. The findings obtained are summarized as follows. (1) Prec ipitation stripping of AgSCN was almost impossible when water, aqueous NH3 or NaOH was used as stripping solution, (2) Stripping or precipitation stri pping reactions did not proceed quantitatively when HClO4 or NaClO4, whose affinity for amine is strong, was used as stripping solution. (3) When NH3 or NaOH solution containing NaBH4 was used, reduction stripping proceeded p roducing aggregates of fine metallic Ag powder. (4) For efficient reduction stripping of Ag using a solution containing NaBH4, the addition of NH3 or NaOH, and the use of NaBH4 at more than twice the amount of Ag(I) in the or ganic phase, are required. (5) When Ag(I) extraction was done using Primene JMT that had been converted to the thiocyanate salt, the reduction efficie ncy deteriorated. (C) 1999 Elsevier Science B.V. All rights reserved.