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.