| 摘要 |
<p>PURPOSE:To improve remarkably the recovery rate of silver and to decrease the burden of the succeeding washing liquid by removing the lead in the silver chloride residue obtd. by gaseous chlorine leaching of the precipitate of copper electrolysis or decopperization thereof then reducing the silver decoction by sodium thiosulfate. CONSTITUTION:The precipitate of copper electrolysis byproduced in an electrolytic refining stage of copper or the precipitate of decopperization obtd. by decopperizing and dearsenizing said precipitate is subjected to gaseous chlorine leaching in the slurry state. An aq. metallic chloride soln. of NaCl, MgCl2, etc. is more preferably used for making the precipitate into the slurry. The gaseous chlorine is blown to the slurry under stirring at 60-80 deg.C. The resultant slurry is converted to the decoction in which gold is leached at >=99% and the residue in which silver is held in the form of AgCl at >=99%. The resultant residue is washed preferably by heated water (warm or hot water) so that the greater part of the lead in the residue is removed. The residue after removal of the lead is subjected to sodium thiosulfate leaching and reduction stage according to the conventional form of embodiment to obtain reduced silver. The reduced silver is further refined and is recovered finally as high-purity silver of >=99.999%.</p> |
