| 摘要 |
<p>PROBLEM TO BE SOLVED: To develop a method with which impurities are not dissolved into leaching solution in a large amount together with Ag, in leaching a reduced silver directly into nitric acid. SOLUTION: Primary-leaching is performed to the reduced silver to leach and remove easily dissolvable impurities of Pb, etc., and primary-leached residue is leached at multiple-steps with higher concentration of the nitric acid, and at the last step, the leaching is performed under condition of lowering free acid concentration of <=20 g/L by adding Ag-containing residue to restrain the dissolving of coexisting impurities, such as Te.</p> |
