| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent mixing of impurity elements into the objective metals to be reduced, and to precipitate the objective metals to be reduced in high yield by allowing a reducing agent to react under the conditions of the presence of halide ions of a specified concn. in an aq. soln. SOLUTION: By this method, only the objective metals to be reduced are selectively reduced and precipitated while coprecipitation and coreduction of impurity elements are prevented by converting the impurity elements present together with the metal ions in the soln. into halide complexes so as to reduce the reduction potential. Practically, when the objective metal to be reduced is gold, the impurity element present is silver and the halide is chloride, the concn. of the chloride ion present in the liquid is increased so as to prevent both of precipitation of silver chloride and reduction of silver. This method can be also used for the reduction of other metal ions, and is effective for halides except chlorides. The concn. of the halide in the liquid is preferably 0.1 to 13 mol/l.</p> |
